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Seiya Yui, Takumi Mihara, [Tomoki Nishimura](https://orcid.org/0000-0002-9034-3626), [Yasuo Ebina](https://orcid.org/0000-0003-3471-9825), [Takayoshi Sasaki](https://orcid.org/0000-0002-2872-0427), [Koki Sano](https://orcid.org/0000-0002-5702-4252)

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[Multi-functional photonic crystals of modular nanosheets](https://mdr.nims.go.jp/datasets/ce9d5fc4-1c89-45ae-9a77-638bd6327d7a)

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Multi-functional photonic crystals of modular nanosheetsArticle https://doi.org/10.1038/s41467-026-70456-6Multi-functional photonic crystals ofmodular nanosheetsSeiya Yui1, Takumi Mihara1, Tomoki Nishimura 1, Yasuo Ebina 2,Takayoshi Sasaki 2 & Koki Sano 1Photonic crystals with periodically ordered nanoscale building blocks canexhibit structural colors, offering a promising optical platform. Among variousbuilding blocks, colloidal nanosheets have attracted increasing attentionowing to their intrinsic two-dimensionality and stimuli-responsiveness. How-ever, integrating multiple functionalities into nanosheet-based photoniccrystals remains challenging due to the structural and colloidal requirementsof the nanosheets. Here, we established a universal modular strategy for syn-thesizing functional hybrid nanosheets and subsequently constructed multi-functional photonic crystals via their self-assembly. By electrostatically inte-grating negatively charged titanate nanosheets with positively charged nano-particles, including gold nanoparticles, gold nanorods, and fluorescent silicananoparticles, we successfully synthesized functional hybrid nanosheets. Theenhancement of electrostatic repulsionbetween these nanosheets enabled theformation of multi-functional photonic crystals with modularly integratedstructural color, plasmonic absorption, and fluorescence. Finally, we demon-strated three-dimensional visualization of the photonic nanostructures usingconfocalmicroscopy and reversiblemodulation of the optical properties usingmagnetic fields and light. This work provides a versatile platform for designingnext-generation smart photonic materials with integrated functionalities.Photonic crystals, composed of long-range ordered nanostructureswith periodicities on the scale of several hundred nanometers, exhibitstructural colors by selectively reflecting specific wavelengths of lightbased on Bragg’s law1–4. Unlike conventional pigments and dyes thatrely on light absorption, structural colors offer distinct advantages,including color tunability, long-term stability, and environmentalcompatibility. Due to these advantages, structural colors are widelyobserved in nature5–8, and artificial photonic crystals have beenextensivelydeveloped through the self-assembly of nanoscale buildingblocks3,4 for a wide range of applications, such as sensors9,10,displays11,12, printable inks13,14, photonic pigments15,16, opticalanticounterfeiting17, and biomedical applications18. Among variousbuilding blocks, inorganic colloidal nanosheets, synthesized viaexfoliation of layered crystals, have emerged as a promising platformfor constructing dynamic photonic crystals owing to their intrinsictwo-dimensionality and stimuli-responsiveness19–46. For example, werecently established a rational strategy for constructing nanosheet-based dynamic photonic crystals by maximizing electrostatic repul-sion between nanosheets19,23. This strategy enabled the stimuli-responsive modulation of structural colors19,24,25 and led to the devel-opment of unique photonic systems, including mechano-responsivephotonic hydrogels20, dynamic photonic nanostructures capable ofmass transport via propagating waves of the collectively movablenanosheets21, and reconfigurable photonic crystals that can reversiblyswitch between single and double structural colors22. If functionalnanosheets could be harnessed to construct dynamic photonicReceived: 16 May 2025Accepted: 17 February 2026Check for updates1Department of Chemistry andMaterials, Faculty of Textile Science and Technology, ShinshuUniversity 3-15-1 Tokida, Ueda, Nagano, Japan. 2ResearchCenterfor Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS) 1-1 Namiki, Tsukuba, Ibaraki, Japan.e-mail: koki_sano@shinshu-u.ac.jpNature Communications |         (2026) 17:4517 11234567890():,;1234567890():,;http://orcid.org/0000-0002-9034-3626http://orcid.org/0000-0002-9034-3626http://orcid.org/0000-0002-9034-3626http://orcid.org/0000-0002-9034-3626http://orcid.org/0000-0002-9034-3626http://orcid.org/0000-0003-3471-9825http://orcid.org/0000-0003-3471-9825http://orcid.org/0000-0003-3471-9825http://orcid.org/0000-0003-3471-9825http://orcid.org/0000-0003-3471-9825http://orcid.org/0000-0002-2872-0427http://orcid.org/0000-0002-2872-0427http://orcid.org/0000-0002-2872-0427http://orcid.org/0000-0002-2872-0427http://orcid.org/0000-0002-2872-0427http://orcid.org/0000-0002-5702-4252http://orcid.org/0000-0002-5702-4252http://orcid.org/0000-0002-5702-4252http://orcid.org/0000-0002-5702-4252http://orcid.org/0000-0002-5702-4252http://crossmark.crossref.org/dialog/?doi=10.1038/s41467-026-70456-6&domain=pdfhttp://crossmark.crossref.org/dialog/?doi=10.1038/s41467-026-70456-6&domain=pdfhttp://crossmark.crossref.org/dialog/?doi=10.1038/s41467-026-70456-6&domain=pdfhttp://crossmark.crossref.org/dialog/?doi=10.1038/s41467-026-70456-6&domain=pdfmailto:koki_sano@shinshu-u.ac.jpwww.nature.com/naturecommunicationscrystals, they would offer a new platform for integrating additionalfunctionalities, thereby enabling the development of multi-functionalphotonic crystals. However, to self-assemble into photonicnanostructures, the nanosheets must meet several stringent require-ments: uniform thickness and a high aspect ratio to ensure properstructural ordering, a large surface charge density for strong electro-static repulsion, and robust structural and colloidal stability for solu-tion processing. Consequently, inorganic nanosheets available forconstructing photonic crystals have been restricted to specific com-positions, such as titanate19–22, graphene oxide23–32, antimonyphosphate33–35, zirconium phosphate36–39, titanium phosphate40,niobate41,42, and clay minerals43–46. Although various functionalizedinorganic nanosheets (e.g., plasmonic47–52 and fluorescent53–59 proper-ties) have been developed for broad applications, for example, byattaching functional nanoparticles onto the nanosheets47–53, their usein constructing photonic crystals has yet to be realized, primarily dueto their difficulty in satisfying the above stringent structural and col-loidal criteria. In this context, it remains a significant challenge todevelop a universal strategy for synthesizing inorganic nanosheetsthat not only satisfy the criteria but also possess additional function-alities for constructing multi-functional photonic crystals.To address this challenge, in this work, we propose a generalmethod to post-functionalize the base nanosheets known to formphotonic crystals, while retaining their photonic ability, through sur-facemodificationwith functional nanoparticles (Fig. 1a). This approachallows for the modular integration of diverse functionalities intonanosheets simply by varying the nanoparticles, thereby enabling thecreation of multi-functional photonic crystals with tunable opticalproperties. As the base nanosheet, we selected titanate nanosheets(TiNSs)60–62, since we had previously confirmed their ability to formstable photonic nanostructures19–22. By electrostatically combiningnegatively charged TiNSs with a variety of positively charged func-tional nanoparticles, such as gold nanoparticles (AuNPs)63, goldnanorods (AuNRs)64, and fluorescent silica nanoparticles (FSNPs)65,under optimized conditions, we successfully synthesized structurallyand colloidally stable hybrid nanosheets with customizable opticalproperties (Fig. 1b). Subsequently, by enhancing electrostatic repul-sion between these hybrid nanosheets, we expanded their interlayerdistance to several hundred nanometers, resulting in multi-functionalphotonic crystals with modularly integrated structural color, plas-monic absorption, and fluorescence (Fig. 1c). Notably, the use offluorescent nanosheets enabled direct three-dimensional (3D) visuali-zation of individual nanosheets within the photonic nanostructureusing confocal laser scanning microscopy (CLSM). Finally, wedemonstrated reversible modulation of the optical properties of thephotonic crystals by adjusting the nanosheet orientation through theapplication of a strong magnetic field (Fig. 1d), as well as reversibletuning of structural color by manipulating the interlayer distance vialight irradiation (Fig. 1e), reminiscent of photo-responsive structuralcolors of marine organisms6–8. This work highlights a universal mod-ular strategy for the synthesis of functional nanosheets and the sub-sequent development of multi-functional photonic crystals throughtheir self-assembly, thereby expanding the design paradigm for next-generation photonic materials with emergent and integrated opticalfunctionalities.ResultsSynthesis and characterization of hybrid nanosheetsIn this study, we employed negatively charged TiNSs60–62 with athickness of 0.75 nm and a lateral size of several micrometers as thebase nanosheet. TiNSs are well dispersed in water due to their highsurface charge density, forming a periodic nanostructure governed bythe balance between electrostatic repulsion and van der Waalsattraction, as described by the Derjaguin–Landau–Verwey–Overbeek(DLVO) theory19,66. As we previously reported19–22, the enhancement ofthe electrostatic repulsion between TiNSs through deionization canincrease the interlayer distance between TiNSs up to several hundrednanometers, enabling the formation of photonic crystals with vividstructural colors.To modularly impart additional functionalities to TiNSs withoutcompromising their ability to form photonic crystals, we electro-statically attached positively charged functional nanoparticles to thenegatively charged TiNS surfaces under controlled conditions. Ascandidates for functional nanoparticles, we selected AuNPs63 andAuNRs64 for their plasmonic properties and FSNPs65 for their fluor-escent properties. First, we prepared positively charged functionalnanoparticles, where the zeta potentials were measured to be +52mVfor AuNPs, +55mV for AuNRs, and +21mV for FSNPs (SupplementaryFig. 1). Transmission electron microscopy (TEM) images and opticalcharacterizations (extinction and/or fluorescence spectra) revealedthe structural and optical features of the nanoparticles: AuNPs (dia-meter: ~17 nm; plasmonic absorption peak: 525 nm; Fig. 2b), AuNRs(short axis: ~21 nm, long axis: ~38 nm; plasmonic absorption peaks: 520and 615 nm; Fig. 2d), and FSNPs (diameter: ~30 nm; fluorescence peak:578 nm; Fig. 2f).To attach the nanoparticles to the surfaces of TiNSs (Fig. 2a andSupplementary Fig. 2a), the aqueous dispersions of nanoparticles wereslowly added to a dilute dispersion of TiNSs (zeta potential: –51mV;Supplementary Fig. 1), affording hybrid nanosheets with functionalnanoparticles via electrostatic attraction (AuNP-TiNSs, AuNR-TiNSs,and FSNP-TiNSs). TEM images and extinction and/or fluorescencespectra (AuNP-TiNSs in Fig. 2c and Supplementary Fig. 2b; AuNR-TiNSsin Fig. 2e and Supplementary Fig. 2c; FSNP-TiNSs in Fig. 2g and Sup-plementary Fig. 2d) confirmed successful attachment of the nano-particles to the TiNS surfaces while retaining their original opticalproperties. Importantly, the negative charge of the hybrid nanosheetswas almostmaintained even after the attachment of positively chargednanoparticles on the surfaces owing to the controlled low concentra-tions of the added nanoparticles during the synthesis of the hybridnanosheets, as confirmed by zeta potential measurements (Supple-mentary Fig. 1), ensuring the large electrostatic repulsion between thenanosheets. Consequently, the dispersions of the hybrid nanosheetsexhibited liquid-crystalline behavior similar to that of the original TiNSdispersion, as shown in polarized optical microscopy (POM) images(Supplementary Fig. 3). POM images and extinction or fluorescencespectra of the hybrid nanosheets, taken after 7 days of storage or afterheating at 70 °C for 30min (AuNP-TiNSs in Supplementary Fig. 4;AuNR-TiNSs in Supplementary Fig. 5; FSNP-TiNSs in SupplementaryFig. 6), confirmed that their liquid-crystalline behavior and opticalproperties remained essentially unchanged, supporting their long-term and thermal stability.When the concentrations of the added nanoparticles were muchhigher than the optimized values during the synthesis of the hybridnanosheets, the resultant nanosheets aggregated and hardly exhibitedliquid-crystalline behavior, possibly due to a reduction of the surfacecharge of the original TiNSs (Supplementary Fig. 7). In contrast, theaddition of a smaller amount of functional nanoparticles resulted incolloidally stable hybrid nanosheets that retained liquid-crystallinebehavior but showed attenuated optical features (Supplementary Fig.8). By using a mixture of AuNRs and FSNPs for the synthesis of hybridnanosheets, we obtained dual-functional hybrid nanosheets withAuNRs and FSNPs (AuNR/FSNP-TiNSs) that exhibited both plasmonicand fluorescent properties (Fig. 2i and Supplementary Figs. 2e and 3e).Even when the ratio between AuNRs and FSNPs was varied whilekeeping the amount of added AuNRs constant, the plasmonic prop-erties remained essentially unchanged, indicating no significant com-petitive adsorption between AuNRs and FSNPs (Supplementary Fig. 9).Remarkably, we successfully visualized individual hybridnanosheets (FSNP-TiNSs) dispersed in water using fluorescencemicroscopy (Fig. 2h). It is noteworthy that the real-time movement ofArticle https://doi.org/10.1038/s41467-026-70456-6Nature Communications |         (2026) 17:4517 2www.nature.com/naturecommunicationsthe ultrathin nanosheets can be directly monitored (SupplementaryMovie 1), contributing to the analysis of their self-assembly anddynamic behavior. Even after one month of storage (SupplementaryFig. 10a) or heating at 70 °C for 30min (Supplementary Fig. 10b), thehybrid nanosheets remained clearly visible, further supporting thestable and robust attachment of nanoparticles to the TiNS surfacesin water. These results demonstrate the universality and robustnessof our strategy for synthesizing structurally and colloidallystable hybrid nanosheets with modularly integrated functionalities,offering a versatile platform for the development of multi-functional photonic crystals as well as a wide variety of other smartsoft materials.Magnetically induced orientation control of hybrid nanosheetsAmagnetic field serves as an effective external stimulus to control theorientation of nanosheets. In our previous studies, we demonstratedStep 1: Modular synthesis of hybrid nanosheets Step 2: Construction of multi-functional photonic crystals from hybrid nanosheets van derWaalsattractionMulti-functional photonic crystalSeveral hundred nm Electrostaticrepulsion Electrostaticrepulsion van derWaalsattractiona＋ElectrostaticattractionElectrostaticrepulsionBase nanosheet Functional nanoparticles Hybrid nanosheet0.75 nmTitanate nanosheet (TiNS)for photonic propertyNegatively charged surface Negatively charged surfacePositively charged surfaceStep 1 Step 2Lateral size: Several µmThickness: 0.75 nmGold nanoparticle (AuNP)Gold nanorod (AuNR) for plasmonic propertyFluorescent silicananoparticle (FSNP)for uorescent propertyPlasmonic property+ Photonic propertyPlasmonic absorptionStructural color FluorescenceStructural colorFluorescent property+ Photonic propertyFluorescenceStructural colorFluorescent property+ Plasmonic property+ Photonic propertyPlasmonic absorptionAuNP-TiNS FSNP-TiNSAuNR-TiNS AuNR/FSNP-TiNSAuNP forplasmonic propertyAuNR forplasmonic propertyFSNP foruorescent propertyAuNR forplasmonic propertyFSNP foruorescent property＋bAuNP-TiNSs and AuNR-TiNSs FSNP-TiNSs AuNR/FSNP-TiNSs++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++Diameter: ~17 nm++++++++++++Diameter: ~30 nm++++++ + + + ++ + + + ++++++++++++++++++++++ + + + ++ + + + ++++Short axis: ~21 nmLong axis: ~38 nm Diameter: ~30 nmShort axis: ~21 nmLong axis: ~38 nmStep 3: Optical modulation of multi-functional photonic crystals using external stimuliPlasmonic absorptionPlasmonic absorptionMagnetPlasmonic property+ Photonic property Plasmonic propertyMagneticorientationAuNP-TiNSsPlasmonic absorptionPlasmonic absorptionAuNP-TiNSsLong-wavelengthstructural colorShort-wavelengthstructural colorPhoto-Induced control of structural colorMagneto-induced switching of optical propertyd eLight ONLight OFFMagnetPhotonic propertyStructural colorcTiNSsStructuralcolorStructural colorFig. 1 | Synthesis and control of multi-functional photonic crystals composedof hybrid nanosheets with modularly integrated properties. a Schematic illus-trations of a modular method for synthesizing functional hybrid nanosheets byelectrostatically combining negatively charged titanate nanosheets (TiNSs) withvarious positively charged functional nanoparticles, including gold nanoparticles(AuNPs), gold nanorods (AuNRs), and fluorescent silica nanoparticles (FSNPs), andconstructing multi-functional photonic crystals by enhancing the electrostaticrepulsion between the nanosheets. b Schematic illustrations of hybrid nanosheetswith modularly integrated properties. c Schematic illustrations of multi-functionalphotonic crystals composed of hybrid nanosheets with customizable functional-ities, including structural color, plasmonic absorption, and fluorescence.d, e Schematic illustrations of (d) magneto-induced switching of optical propertiesand (e) photo-induced control of structural color of a photonic crystal ofAuNP-TiNSs.Article https://doi.org/10.1038/s41467-026-70456-6Nature Communications |         (2026) 17:4517 3www.nature.com/naturecommunicationsremote control of the orientation of TiNSs19–22 and graphene oxidenanosheets24,25 in their photonic crystals using a strong magnetic field(e.g., 10 T) for the modulation of structural colors. To investigate themagnetically responsive behaviors of the hybrid nanosheets in thiswork, we performed small-angle X-ray scattering (SAXS) measure-ments at the SPring-8 synchrotron radiation facility. The 2D-SAXSimages of TiNSs (Fig. 3b) suggest that TiNSs were randomly orientedwithout a magnetic field (Fig. 3a, i), whereas the application of a 12 Tmagnetic field induced the perpendicular orientation of the TiNSplanes to the appliedmagnetic field (Fig. 3a, ii). The 2D-SAXS images ofthe hybrid nanosheets exhibit profiles that were nearly identical tothose of TiNSs (AuNP-TiNSs in Fig. 3c; AuNR-TiNSs in Fig. 3d; FSNP-TiNSs in Fig. 3e; AuNR/FSNP-TiNSs in Fig. 3f), indicating that thenanosheet planes likewise aligned perpendicular to themagnetic field.The macroscopic orientability was further supported by POM obser-vations (Supplementary Fig. 11). These results revealed that the mag-netic orientability of TiNSs is preserved even after the integration offunctional nanoparticles, allowing for precise magnetic control overthe orientation of the hybrid nanosheets.Construction of multi-functional photonic crystals from hybridnanosheetsAs we previously reported19–25, the key to constructing dynamic pho-tonic crystals from colloidal nanosheets lies in enhancing the elec-trostatic repulsion between the nanosheets, for instance, bydeionization through repeated centrifugation and redispersion cycles.By applying this approach to AuNP-TiNSs, we successfully constructeda photonic crystal composed of AuNP-TiNSs that exhibited a structuralcolor. Comparison of the SAXS profile and the UV-Vis spectrum of thephotonic crystal indicated that the structural color followed Bragg’slaw (Supplementary Fig. 12)67. The UV-Vis spectrum of the AuNP-TiNSdispersion at a concentration of 0.40wt% in a quartz cuvette (40 ×10 × 1mm), measured in transmission mode, displayed two char-acteristic peaks (Fig. 4a): one peak at around 650nmcorresponding to100 µm 20 µmWavelength (nm)400 500 700Extinction (a.u.)600Wavelength (nm)400 500 700Extinction (a.u.)600Wavelength (nm)400 500 700Extinction (a.u.)600Wavelength (nm)400 500 700Extinction (a.u.)600Wavelength (nm)400 500 700Extinction (a.u.)600TiNS AuNP-TiNS AuNR-TiNSFSNPAuNP AuNRWavelength (nm)400 500 700Extinction/FL (a.u.)600Wavelength (nm)400 500 700600Wavelength (nm)400 500 700600FSNP-TiNS AuNR/FSNP-TiNSPlasmonicFluorescence Fluorescence FluorescencePlasmonic PlasmonicPlasmonicPlasmonicPlasmonicPlasmonic PlasmonicAbsorptionha b c d ef g i++++++++++++++++++++++++++++++ + + + ++ + + + ++++50 nm 200 nm 50 nm 300 nm100 nm 200 nm 200 nm(ii)(iv)(i)(ii)(iv)(ii)(iv)(ii)(iv)(ii)(iv)(ii)(iv)(i)(ii)(iv)(ii)(iv)(i) (i) (i) (i)(i) (i)(iii) (iii) (iii) (iii) (iii)(iii)(iii)(iii)300 nmExtinction/FL (a.u.)Extinction/FL (a.u.)Fig. 2 | Characteristics of hybrid nanosheets. a–e (i) Schematic illustrations, (ii)transmission electron microscopy (TEM) images, (iii) optical images of the dis-persions, and (iv) extinction spectra of (a) titanate nanosheets (TiNSs), (b) goldnanoparticles (AuNPs), (c) AuNP-functionalized TiNSs (AuNP-TiNSs), (d) goldnanorods (AuNRs), and (e) AuNR-functionalized TiNSs (AuNR-TiNSs). f, g (i) Sche-matic illustrations, (ii) TEM images, (iii) optical images of the dispersions under UVillumination, and (iv) extinction (navy line) and fluorescence (green line) spectra of(f) fluorescent silica nanoparticles (FSNPs) and (g) FSNP-functionalized TiNSs(FSNP-TiNSs).h Fluorescencemicroscopy image of an aqueous dispersion of FSNP-TiNSs. i (i) Schematic illustration, (ii) TEM image, (iii) optical image of the disper-sion, and (iv) extinction (navy line) and fluorescence (green line) spectra of TiNSsfunctionalized with both AuNRs and FSNPs (AuNR/FSNP-TiNSs).Article https://doi.org/10.1038/s41467-026-70456-6Nature Communications |         (2026) 17:4517 4www.nature.com/naturecommunicationsthe structural color arising from the photonic nanostructure of thenanosheets and the other peak at 515 nm due to plasmonic absorptionof AuNPs on the nanosheet surfaces. Upon applying a 12 T magneticfield parallel to the observation direction (i.e., along the z-axis inFig. 4b), all AuNP-TiNSs aligned perpendicular to the appliedmagneticfield, resulting in a uniform structural color (Fig. 4b, ii). Consequently,the peak intensity of the structural color increased in the UV-Visspectrum, while the plasmonic absorption peak remained almostunchanged (Fig. 4b, iii and Supplementary Fig. 13b, i). In the reflectionspectra, the reflection peaks corresponding to the structural colorwere also observed, whereas the plasmonic absorption peak was notdetected (Supplementary Fig. 13b, iii). The peak positions of thestructural color were almost identical to those of a photonic crystal ofpristine TiNSs, although the peaks of AuNP-TiNSs were broader, pos-sibly due to slight structural disorder in the photonic nanostructures(Supplementary Fig. 13a, b). The photonic crystal retained its originaloptical properties even after 7 days of storage (Supplementary Fig. 14).When the 12 T magnetic field was applied perpendicular to theobservation direction (i.e., along the y-axis in Fig. 4c), the structuralcolor disappeared, and only the red plasmonic color remained visible(Fig. 4c). Accordingly, the structural color peak disappeared in the UV-Vis spectrum, while the plasmonic absorption peak remained almostconstant. These results highlight the potential for magneto-inducedmodulation of the optical properties in the photonic crystals.Based on these results, we further constructed multi-functionalphotonic crystals using other hybrid nanosheets at a concentration of0.50wt% and subjected them to the magnetic treatment (AuNR-TiNSsin Fig. 4d; FSNP-TiNSs in Fig. 4e; AuNR/FSNP-TiNSs in Fig. 4f). Asexpected, a photonic crystal composed of AuNR-TiNSs exhibited bothphotonic and plasmonic properties (Fig. 4d). In the UV-Vis spectrummeasured in transmissionmode, theoverlappingpeakof the structuralcolor and plasmonic absorption of AuNRs was observed at around520nm and the other plasmonic absorption peak of AuNRs wasdetected at around 620 nm (Fig. 4d and Supplementary Fig. 13d, i). Inthe reflection spectrum, the reflection peaks of the structural colorwere similarlyobserved,whereas theplasmonic absorptionpeakswerenot detected (Supplementary Fig. 13d, iii). The peak positions of thestructural color were almost identical to those of a photonic crystal ofpristine TiNSs, although the peaks of AuNR-TiNSs were broader, pos-sibly due to slight structural disorder in the photonic nanostructures(Supplementary Fig. 13c, d). Additionally, a photonic crystal composedof FSNP-TiNSs displayed both photonic and fluorescent properties, asevidenced by the structural color peak at 511 nm in the UV-Vis spec-trum and the fluorescence peak at 578 nm arising from FSNPs on thenanosheet surfaces in the fluorescence spectrum (Fig. 4e). Finally, wesuccessfully constructed a photonic crystal composed of AuNR/FSNP-TiNSs, which simultaneously exhibited photonic, plasmonic, andfluorescent properties. In this case, the UV-Vis spectrum revealed theoverlapping peak corresponding to both the structural color andplasmonic absorption, as well as the other plasmonic absorption peakof AuNRs, while the fluorescence spectrum revealed the emission peak(Fig. 4f).Three-dimensional structural characterization of multi-functional photonic crystalsTo investigate the internal nanostructures of these photonic crystals,we employed CLSM to three-dimensionally visualize the fluorescentnanosheets (FSNP-TiNSs). After fixing the magnetically treated pho-tonic crystal of FSNP-TiNSs (0.40wt%)via in situ photo-induced radicalpolymerization, we performed CLSM imaging of the resultant hydro-gel in a wet state. As shown in Fig. 4g, we achieved 3D visualization ofthe photonic nanostructure composed of nanosheets, in which theindividual nanosheets, along with their lamellar arrangement andorientation, were clearly observed despite their ultrathin nature.X-rayw/o B X-rayw/o B w/o B w/o B w/o B w/o BTiNS AuNP-TiNS AuNR-TiNS FSNP-TiNS AuNR/FSNP-TiNSb c d e f(i) (i) (i) (i) (i)(ii) (ii) (ii) (ii) (ii)B B B B Ba(i)(ii)RandomorientationUnidirectionalorientation0 90 180 270 360 0 90 180 270 360 0 90 180 270 360 0 90 180 270 360 0 90 180 270 360(iii) (iii) (iii) (iii) (iii)w/o B w/o B w/o B w/o B w/o Bw/ B w/ B w/ B w/ B w/ BSide view ofnanosheetBNormalizedintensity (a.u.)Fig. 3 | Magnetic orientability of hybrid nanosheets. a Schematic illustrations ofthe side view of a nanosheet: (i) random and (ii) perpendicular orientation of thenanosheet plane without and with the application of a magnetic field, respectively.b–f Two-dimensional small-angle X-ray scattering (2D-SAXS) profiles of thenanosheets at a concentration of 0.050wt% (b: TiNSs; c: AuNP-TiNSs; d: AuNR-TiNSs; e: FSNP-TiNSs; f: AuNR/FSNP-TiNSs) fixed in hydrogels (i) without (0 T) and(ii) with (12 T) the application of a magnetic field. (iii) Azimuthal angle plotsobtained from the corresponding 2D-SAXS profiles.Article https://doi.org/10.1038/s41467-026-70456-6Nature Communications |         (2026) 17:4517 5www.nature.com/naturecommunicationsMoreover, we succeeded in visualizing individual nanosheets dis-persed in water without any structural fixation such as hydrogelation.Consequently, we observed the time-dependent structural relaxationof the nanosheets fromamagnetically oriented state to a random state(Supplementary Fig. 15 and SupplementaryMovie 2) and their dynamicbehavior within giant vesicles (Supplementary Fig. 16 andSupplementary Movie 3). These results are particularly noteworthygiven the intrinsic trade-off that exists between the spatial resolutionrequired to visualize individual nanosheets and the ability to resolvetheir self-assembled nanostructures. Under dilute conditions, isolatedfluorescent nanosheets can be visualized using fluorescence micro-scopy and CLSM54,55. However, in the self-assembled or stacked state,FluorescenceBStructural colorFluorescent property+ Plasmonic property+ Photonic propertyPlasmonic absorptionBPlasmonic absorptionPlasmonic absorptionStructural colorBPlasmonic property+ Photonic property Plasmonic propertyPlasmonic property+ Photonic propertyPlasmonic PlasmonicPlasmonicPlasmonic absorptionStructural colorWavelength (nm)450 500 600 700550 650Extinction (a.u.)Wavelength (nm)450 500 600 700550 650Extinction (a.u.)Wavelength (nm)450 500 600 700550 650Extinction (a.u.) BWavelength (nm)450 500 600 700550 650Extinction (a.u.)Wavelength (nm)450 500 600 700550 650Extinction/FL (a.u.)Wavelength (nm)450 500 600 700550 650Extinction/FL (a.u.)Plasmonic absorptionStructural colorBPlasmonic property+ Photonic propertyFluorescenceBStructural colorFluorescent property+ Photonic propertyPlasmonica b cd e fyzx yzx yzxxyzw/o Byzx yzx yzxAuNP-TiNSs AuNP-TiNSs AuNP-TiNSsxyzxyzAuNR-TiNSs FSNP-TiNSs AuNR/FSNP-TiNSsxyzxyzxyzPhotonicPhotonicPhotonicPlasmonicBB B5 mm 5 mm 5 mm5 mm 5 mmw/o Bg(i) (i) (i)(i) (i) (i)(ii) (iii) (ii) (iii) (ii) (iii)(ii) (iii) (ii) (iii) (ii) (iii)B3D viewHeight(µm)BTop view020406080100120(µm)0 2040 6080100120(µm)01020304050Height(µm)Side view B02550FluorescencePhotonicPlasmonicFluorescencePlasmonicPhotonicB5 mm20 µmFig. 4 | Characteristics of multi-functional photonic crystals composed ofhybrid nanosheets. a–c (i) Schematic illustrations, (ii) optical images, and (iii) UV-Vis spectra of the photonic crystal of AuNP-TiNSs (0.40wt%) (a) before and(b, c) aftermagnetic application along the (b) z-axis and (c) y-axis.d–f (i) Schematicillustrations, (ii) optical images, and (iii) UV-Vis (navy line) and fluorescence (greenline) spectra of the magnetically treated photonic crystals of (d) AuNR-TiNSs(0.50wt%), (e) FSNP-TiNSs (0.50wt%), and (f) AuNR/FSNP-TiNSs (0.50wt%). g Areconstructed 3D confocal laser scanning microscopy (CLSM) image of the mag-netically treated photonic crystal of FSNP-TiNSs (0.40wt%; left) and the corre-sponding top and side views (right) obtained using a 570-nm laser.Article https://doi.org/10.1038/s41467-026-70456-6Nature Communications |         (2026) 17:4517 6www.nature.com/naturecommunicationsindividual nanosheets are generally difficult to resolve due to over-lapping and structural complexity, thereby limiting visualization totheir macroscopic architecture56–59. Consequently, direct visualizationof individual nanosheets within their self-assembled nanostructureshas remained a significant challenge. In this study, we demonstratethat CLSM imaging with our fluorescent nanosheets overcomes thischallenge, because the photonic nanostructure of the nanosheetsensures a sufficiently large interlayer distance, enabling their indivi-dual resolution under CLSM. These findings provide a versatile plat-form for precise analysis and further exploration of the self-assemblyand dynamic behavior of colloidal nanosheets.Optical control of multi-functional photonic crystalsTo investigate the optical controllability of multi-functional photoniccrystals, we first examined the effect of nanosheet concentration([AuNP-TiNS]) on their optical properties, including structural colorand plasmonic absorption. An aqueous dispersion of AuNPs alonedisplayed a plasmonic absorption peak at 525 nm, resulting in a redappearance (Fig. 5a). Upon increasing [AuNP-TiNS] from 0.40 to0.60wt%, the first-order structural color peak of the AuNP-TiNS pho-tonic crystals showed a continuous blue shift from 1235 to 877 nm,while the plasmonic absorption peak remained nearly unchanged ataround 525 nm. Accordingly, the second-order structural color peak inthe visible region was also blue-shifted, accompanied by a gradualcolor change from pink to yellow, green, and finally blue. This blueshift is attributed to a decrease in the interlayer distance betweenAuNP-TiNSs with increasing [AuNP-TiNS], in accordance with Bragg’slaw19. We then examined how the ionic concentration ([NaCl]) and pHaffected the optical properties. We found that increasing [NaCl] orlowering pH led to a blue shift of the structural color, as the reducedelectrostatic repulsion between AuNP-TiNSs decreased their interlayerdistance (Supplementary Fig. 17).Next, we aimed to realize reversible switching of optical proper-ties (i.e., structural colors and plasmonic absorption) by applying astrong magnetic field to align the hybrid nanosheets within the pho-tonic crystal. When a 12 T magnetic field was applied to the photoniccrystal of AuNP-TiNSs (0.50wt%) along the z-axis in Fig. 5b, thenanosheet planes aligned perpendicular to the observation direction.As a result, the photonic crystal exhibited a vivid green structuralcolor, and the UV-Vis spectrum displayed two peaks corresponding tothe structural color (first order: 1016 nm; second order: 515 nm) andplasmonic absorption (515 nm). In contrast, the application of themagnetic field along the y-axis in Fig. 5b induced the nanosheet planesto align parallel to the observation direction. Consequently, the greenstructural color disappeared and only the red plasmonic colorremained visible, where a single peak corresponding to the plasmonicabsorption at 513 nm was observed in the UV-Vis spectrum (Fig. 5b).We confirmed angle-dependent changes in the structural color bygradually varying the angle of the applied magnetic field, whichshowed a blue shift consistent with Bragg’s law (Supplementary Fig.18). The magneto-induced switching was fully reversible, enablingdynamic modulation between photonic/plasmonic and purely plas-monic states. Furthermore, we successfully converted the photonic/plasmonic state into thepurely plasmonic state usingphotonic crystalsof AuNP-TiNSs and AuNR-TiNSs with different nanosheet concentra-tions (Supplementary Fig. 19). Importantly, the photonic crystals ofAuNP-TiNSs and AuNR-TiNSs exhibited controllable structural colorsas well as plasmonic red and blue colors, respectively, demonstratingtheir potential as photonic inkswith unique reflection- and absorption-based coloration (Supplementary Fig. 20).It is known that certain marine organisms, including neon tetrafish6, sapphirinid copepods7, and brown algae8, can change theirstructural colors in response to light. Inspired by such organisms, weenvisioned that the photo-thermal effect of AuNPs68–70 could be har-nessed to achieve photo-inducedmodulation of the structural color inthe AuNP-TiNS photonic crystal. This idea was based on our previousfinding that the TiNS-based photonic crystals exhibit thermallyresponsive structural colors due to temperature-dependent electro-static repulsion between TiNSs19,22. Therefore, we hypothesized thatphoto-induced heating through the efficient photo-thermal conver-sion of AuNPs68–70 could decrease the interlayer distance betweenAuNP-TiNSs, thereby causing ablue shift in structural color. To test thishypothesis, the photonic crystal of AuNP-TiNSs (0.60wt%) in a quartzcuvette (40× 10 × 1mm) was irradiated with green LED light (525 nm)corresponding to the plasmonic absorptionwavelength (~525 nm), andtemperature changes were monitored using a thermal imaging cam-era. As shown in Fig. 5c, ii and iii, the temperature increased to 43 °Cwithin 10min under light irradiation and decreased to 28 °C within10min after the light was turned off. In contrast, the control photoniccrystal composed only of TiNSs (0.60wt%) exhibited a negligibletemperature change under the same conditions (Fig. 5c, iii and Sup-plementary Fig. 21). The UV-Vis spectra of the photonic crystal ofAuNP-TiNSs (0.60wt%) recorded before and after light irradiationrevealed a reversible blue shift in the structural color peakupon 10minlight irradiation and recovery to the original peak position after aircooling (Fig. 5c, iv). These results demonstrate that the photo-thermaleffect of integrated AuNPs on the nanosheet surfaces enabled thephoto-induced reversible modulation of the structural color, high-lighting the potential of multi-functional photonic crystals as a versa-tile platform for a wide range of applications.DiscussionIn summary, we have developed a modular strategy for synthesizinghybrid nanosheets with tailored functionalities by electrostaticallyintegrating negatively charged titanate nanosheets, which can inher-ently self-assemble into photonic crystals, with a wide range of posi-tively charged functional nanoparticles, including fluorescent silicananoparticles as well as plasmonic gold nanoparticles and nanorods.The resultant hybrid nanosheets retain the intrinsic ability of the ori-ginal titanate nanosheets to form photonic crystals and exhibit thediverse functionalities imparted by the incorporated nanoparticles.Consequently, we successfully constructed multi-functional photoniccrystals with modularly integrated properties, including structuralcolor, plasmonic absorption, and fluorescence, which are essentiallydifferent from the conventional multi-functional photonic crystalscomposed of spherical nanoparticles71–75. The modular nature of thisstrategy facilitates systematic and orthogonal integration of multiplecomponents, offering precise control over the optical properties ofthe photonic crystals. Moreover, the optical properties can be rever-sibly modulated by external stimuli, such as magnetic fields and light.Notably, theuseoffluorescent nanosheets synthesized via our strategyenabled direct 3D visualization of individual nanosheets within thephotonic nanostructure using CLSM. This approach offers a significantadvantage for the analysis of the self-assembled nanostructures ofcolloidal nanosheets, overcoming the limitations of conventional SEMmethods, which typically require complicated fixation and dryingprocedures that often disrupt the original architectures. Overall, theseresults demonstrate that this modular strategy provides not only aversatile platform for synthesizing functional nanosheets and con-structing multi-functional photonic crystals through their self-assem-bly, but also an effective method for investigating the self-assemblednanostructures and dynamic behavior of nanosheets. We anticipatethat this strategy will open new avenues for the design of next-generation photonic materials with emergent and integrated opticalfunctionalities.MethodsGeneralThemagneticorientation of colloidal nanosheetswas carried out usinga Cryogenic model CFM-12T-100-H3 superconducting magnet with aArticle https://doi.org/10.1038/s41467-026-70456-6Nature Communications |         (2026) 17:4517 7www.nature.com/naturecommunications0.40[AuNP-TiNS] (wt%)0.50 0.55 0.600.45 AuNP BPlasmonic absorptionPlasmonic absorptionStructural colorBExtinction (a.u.)Plasmonic property+ Photonic property Plasmonic propertyPhotonicPlasmonicPlasmonicPhotonicPlasmonicPlasmonicPhotonicPlasmonicWavelength (nm)400 850 400 850 400 850 400 850 400 850 1300(1) Magneticorientation(2) MagneticorientationbyzxxyzB BB B BPhotonic Photonic Photonica(1) (2) (1) (2)5 mm5 mmTemperaturec10 mm205040300 10 20 30 40 50 60Time (min)Light ON Light OFF Light ON Light OFF Light ON Light OFFLight ON Light OFF Light ON Light OFF Light ON Light OFFTiNSAuNP-TiNS0 min 10 min 20 min 30 min 40 min 50 min 60 minPlasmonic absorptionStructural colorPlasmonic absorptionStructural colorLight ONLong-wavelengthstructural colorShort-wavelengthstructural colorPhoto-thermalheatingPlasmonic absorptionStructural colorLong-wavelengthstructural colorAir-coolingLight OFF(i) (i)(ii)(iii)(i)(ii)(iii)Green LEDExtinction (a.u.)Wavelength (nm)400 600 1000 1400800 1200AuNP0.600.550.500.450.40Photonic(2nd order)Photonic(1st order)(ii) Plasmonic[AuNP-TiNS](wt%)400 420 440 460 480 500Wavelength (nm)Extinction (a.u.)InitialstateLightONLightOFFLightONLightOFFLightONLightOFFPhotonic(iv)Fig. 5 | Optical modulation of multi-functional photonic crystals. a (i) Opticalimages and (ii) UV-Vis spectra of the magnetically treated photonic crystals ofAuNP-TiNSs with different concentrations (0.40–0.60wt%) and an aqueous dis-persion of AuNPs (0.0036wt%).b (i) Schematic illustrations, (ii) optical images, and(iii) UV-Vis spectra of the photonic crystal of AuNP-TiNSs (0.50wt%) afteralternating magnetic applications along the z-axis and y-axis. c (i) Schematic illus-trations, (ii) thermal images, (iii) corresponding temperature profiles, and (iv) UV-Vis spectra of the magnetically treated photonic crystal of AuNP-TiNSs (0.60wt%)before and after 10min of green light irradiation.Article https://doi.org/10.1038/s41467-026-70456-6Nature Communications |         (2026) 17:4517 8www.nature.com/naturecommunications100mm bore. Centrifugation was performed using a TOMY modelCAX-571 centrifuge equipped with a TOMY model CA-16 rotor. Trans-mission electronmicroscopy (TEM)was carriedout using a JEOLmodelJEM-2100 electron microscope. Polarized optical microscopy (POM)and fluorescence microscopy were performed using a Nikon modelEclipse LV100N POL optical polarizing microscope equipped with aNikonmodel LV-UEPI2 universal illuminator and a Nikonmodel D-LEDILED light source. Zeta potentialmeasurementswere conductedusing aMalvern model Zetasizer Pro.MaterialsHexadecyltrimethylammonium bromide (CTAB), sodium 3-methylsa-licylate, N,N-dimethylacrylamide, N,N’-methylenebisacrylamide,sodium chloride (NaCl), and 1,2-dioleoyl-sn-glycero-3-phosphocholine(DOPC) were purchased from Tokyo Chemical Industry (TCI). Triso-dium citrate, hydrochloric acid (HCl), D-glucose, methanol, anddichloromethane were purchased from FUJIFILMWako Pure ChemicalCorporation. Gold(III) chloride trihydrate, silver(I) nitrate, sodiumborohydride, ascorbic acid, and 1,2-dioleoyl-sn-glycero-3-phos-phoethanolamine-N-(7-nitro-2-1,3-benzoxadiazol-4-yl) (NBD-PE) werepurchased from Sigma-Aldrich. Fluorescent silica nanoparticles (NH2-modified sicastar-redF; diameter: 30nm) were purchased frommicromod. Ultrapurewater was produced by aMilliporemodelMilli-QIQ 7003 water purification system and used throughout the experi-ments. Polymerization inhibitors in N,N-dimethylacrylamide wereremoved using inhibitor removers (Sigma-Aldrich) prior to use. The as-received aqueous dispersions (30 and 15 µL) of fluorescent silicananoparticles (FSNPs; 2.5wt%) were diluted to final volumes of 1.5mLand 1.0mL using HCl solutions (1.0mM and 1.5mM, respectively). Theresultant dilute FSNP dispersions (0.050wt% and 0.038wt%) wereused for the synthesis of hybrid nanosheets (FSNP-TiNSs andAuNR/FSNP-TiNSs, respectively). An aqueous dispersion of titanatenanosheets (TiNSs) with tetramethylammonium countercations wasprepared according to a reported method60,61. After deionization byrepeated centrifugation and redispersion cycles19–22, the TiNSdispersion was used for the synthesis of hybrid nanosheets. Unlessotherwise noted, all reagents were used as received from commercialsuppliers.Synthesis of positively charged gold nanoparticlesGold nanoparticles (AuNPs) were synthesized according to a reportedmethod69,70. Briefly, an aqueous solutionof gold(III) chloride trihydrate(0.25mM, 300mL) was heated to 90 °C, and an aqueous solution oftrisodium citrate (40mM, 6.0mL) was rapidly injected into the solu-tion under stirring at 600 rpm. After 10min of reaction, an aqueousdispersion of negatively charged AuNPs was obtained. After cooling toroom temperature, 40mL of the dispersion was purified by two cyclesof centrifugation at 5000×g for 1 h and redispersion in water, andfinally concentrated to a volume of 5.0mL. To convert the surfacecharge of AuNPs from negative to positive, an aqueous solution ofCTAB (20mM, 2.0mL) was rapidly added to the AuNP dispersion(5.0mL). The excess CTAB was removed by centrifugation at 5000×gfor 1 h. After this treatment, the zeta potential of AuNPs changed from–33mVto+52mV, confirming the successfulmodification topositivelycharged AuNPs.Synthesis of positively charged gold nanorodsGold nanorods (AuNRs) were synthesized according to a reportedmethod76. Briefly, to prepare the seed dispersion, an aqueous solutionof sodium borohydride (6.0mM, 1.0mL) was rapidly injected at 25 °Cinto 10mL of an aqueous solution containing gold(III) chloride trihy-drate (0.25mM) and CTAB (100mM) under vigorous stirring at 1200rpm. After 2min of reaction, the stirring was stopped, and the dis-persion was left undisturbed for 1 h. To prepare the growth solution,9.0 g of CTAB and 1.1 g of sodium 3-methylsalicylate were dissolved in250mL of hot water, followed by the addition of an aqueous solutionof silver(I) nitrate (4.0mM, 6.0mL) at 30 °C, and themixture was keptundisturbed for 15min. Subsequently, an aqueous solution of gold(III)chloride trihydrate (1.0mM, 250mL) was added under stirring at 400rpm for 15min, followed by the rapid addition of an aqueous solutionof ascorbic acid (64mM, 1.0mL) under vigorous stirring for 30 s.Finally, 0.80mL of the seed dispersion was rapidly added into thegrowth solution under stirring for 30 s, and the mixture was leftundisturbed at 30 °C for at least 12 h, resulting in an aqueous disper-sion of positively charged AuNRs. The dispersion was purified bycentrifugation at 20,000×g for 1 h and redispersion in water, followedby an additional cycle of centrifugation at 5000×g for 1 h and redis-persion in water.Synthesis of hybrid nanosheets and construction of multi-functional photonic crystalsTo synthesize AuNP-TiNSs, an aqueous dispersion of positivelycharged AuNPs (0.0045wt%, 2.0mL) was slowly added to an aqueousdispersion of TiNSs (0.050wt%, 10mL) under stirring at 500 rpm. Tosynthesize AuNR-TiNSs, an aqueous dispersion of positively chargedAuNRs (0.0053wt%, 2.0mL) was slowly added to an aqueous disper-sion of TiNSs (0.050wt%, 10mL) under stirring at 500 rpm. To syn-thesize FSNP-TiNSs, an aqueous dispersion of positively chargedFSNPs (0.050wt%, 1.5mL) was added in a stepwise manner to anaqueous dispersion of TiNSs (0.050wt%, 10mL). To synthesize AuNR/FSNP-TiNSs, a mixture of the AuNR dispersion (0.011wt%, 0.50mL)and the FSNP dispersion (0.038wt%, 1.0mL) was slowly added to anaqueous dispersion of TiNSs (0.050wt%, 10mL) under stirring at500 rpm. The resultant dispersions were subjected to two cycles ofcentrifugation at 20,000×g for 20min and redispersion in water,leading to the construction of multi-functional photonic crystals.Optical characterizationsUV-Vis spectra and fluorescence spectra were recorded using a JASCOmodel V-770 spectrophotometer and a JASCO model FP-8350 spec-trofluorometer, respectively. Extinction spectra (E = –log10(I/I0), whereI and I0 denote the transmitted intensities through the sample and thereference, respectively) in Fig. 2 and Supplementary Figs. 4, 5, 8, and 9were acquired at room temperature for aqueous dispersions([TiNS] = 0.20wt%; [AuNP] = 0.0036wt%; [AuNP-TiNS] = 0.20wt%;[AuNR] = 0.0053wt%; [AuNR-TiNS] = 0.20wt%; [FSNP] = 0.083wt%;[FSNP-TiNS] = 0.20wt%; [AuNR/FSNP-TiNS] = 0.20wt%) in 1-mm-thickquartz cuvettes (40 × 10 × 1mm). Fluorescence spectra (Fig. 2 andSupplementary Fig. 6) were recorded at room temperature with anexcitation wavelength of 565 nm for aqueous dispersions ([FSNP] =0.083wt%; [FSNP-TiNS] = 0.20wt%; [AuNR/FSNP-TiNS] = 0.20wt%) inquartz cuvettes (45 × 10 × 10mm). All spectra in Fig. 2were normalizedto their maximum values. Optical images shown in Fig. 2 were taken ofaqueous dispersions ([TiNS] = 0.20wt%; [AuNP] = 0.018wt%; [AuNP-TiNS] = 0.20wt%; [AuNR] = 0.0053wt%; [AuNR-TiNS] = 0.20wt%;[FSNP] = 0.050wt%; [FSNP-TiNS] = 0.20wt%; [AuNR/FSNP-TiNS] =0.20wt%). Fluorescence microscopy images shown in Fig. 2h andSupplementary Fig. 10 were obtained from aqueous dispersions ofFSNP-TiNSs (0.0050wt%) under illumination at 550 nm. Extinctionspectra (transmission mode), fluorescence spectra (excitation wave-length: 565 nm), and optical images (Figs. 4 and 5 and SupplementaryFigs. 13, 14, and 17–19) were acquired at room temperature for themulti-functional photonic crystals using 1-mm-thick quartz cuvettes(40 × 10 × 1mm). All spectra in Fig. 4 were normalized to their max-imum values, whereas those in Fig. 5a were normalized to the height ofthe first-order structural color peak of each spectrum. Reflectionspectra (Supplementary Figs. 12b and 13, iii) were recorded at roomtemperature on a JASCO model V-770 spectrophotometer with aJASCO model ARSN-917 manual absolute reflectance measurementunit at an incidence angle of 5°.Article https://doi.org/10.1038/s41467-026-70456-6Nature Communications |         (2026) 17:4517 9www.nature.com/naturecommunicationsSmall-angle X-ray scattering (SAXS) measurementsThe SAXS measurements in Fig. 3 were conducted at the BL40B2beamline of the SPring-8 synchrotron radiation facility (Hyogo, Japan)using aDectrismodel PILATUS3 S 2Mphoton-counting detector (X-raywavelength: 1.0 Å; sample-to-detector distance: 2.1m). The sampleswerepreparedas follows. First, precursor dispersionswereprepared sothat the final concentrations of nanosheets (TiNSs, AuNP-TiNSs, AuNR-TiNSs, FSNP-TiNSs, and AuNR/FSNP-TiNSs), N,N-dimethylacrylamide,and N,N’-methylenebisacrylamide were 0.050, 6.0, and 0.060wt% inwater, respectively. Then, the dispersions were poured into 1-mm-thickcontainers and placed in the bore of a superconductingmagnet. A 12 Tmagnetic field was applied parallel to the container surface for 30min.To fix the magnetically oriented nanosheets within hydrogels, in situphoto-polymerization was carried out by UV irradiation for 30minusing an USHIOmodel OPM2-502H super high-pressure mercury lamp(500W). The macroscopic orientation of the nanosheets was con-firmed by POM observations under crossed Nicols using the resultanthydrogel samples (Supplementary Fig. 11). Samples without the mag-netic application were prepared in the same manner, except for theabsence of a magnetic field. The resultant samples were subjected toSAXS measurements, with the incident X-ray beam directed perpen-dicular to the front surface of the samples. The resulting 2D-SAXSimages were converted into azimuthal angle plots using FIT2D. The 1D-SAXS profile in Supplementary Fig. 12a was acquired at room tem-perature for the photonic crystal of AuNP-TiNSs (2.0wt%) in a quartzcapillary (diameter: 2mm) using a Rigaku model NANOPIX 3.5m sys-tem equipped with a Rigaku model HyPix-6000 detector (X-ray wave-length: 1.54 Å; sample-to-detector distance: 1.4m).Confocal laser scanning microscopy (CLSM) observationsConfocal laser scanning microscopy (CLSM) was carried out using aLeica STELLARIS 8 confocal microscope platform in Lightning mode.The hydrogel sample was prepared as follows. First, the precursordispersion was prepared so that the final concentrations of FSNP-TiNSs, N,N-dimethylacrylamide, and N,N’-methylenebisacrylamidewere 0.40, 10, and 0.10wt% inwater, respectively. Then, the dispersionwas poured into a 0.5-mm-thick container and placed in the bore of asuperconducting magnet. A 12 T magnetic field was applied parallel tothe container surface for 30min. To fix the magnetically orientednanosheets within a hydrogel, in situ photo-polymerizationwas carriedout by UV irradiation for 10min using an USHIO model OPM2-502Hsuper high-pressure mercury lamp (500W). The resultant sample wasobserved at room temperature usingCLSMwith a 570-nm laser, and 2Dimages were acquired at a vertical step size of 0.3 µm. These 2D imageswere reconstructed to provide 3D information regarding the nanosh-eet orientation within the hydrogel (Fig. 4g). To investigate the struc-tural relaxation, an aqueous dispersion of FSNP-TiNSs (0.40wt%) waspoured into a 1-mm-thick container and magnetically treated at 50 °Cfor 30min (12 T). Time-dependent changes in the resultant samplewere monitored at 1-min intervals at room temperature using CLSMwith a 550-nm laser for 5 h (Supplementary Fig. 15 and SupplementaryMovie 2). To visualize the dynamic behavior of nanosheets, the samplewas prepared as follows. First, a mixture of a methanol solution ofDOPC (10mM, 7.5 µL), amethanol solution of D-glucose (20mM, 75 µL),and a dichloromethane solution of NBD-PE (0.11mM, 0.69 µL) waspoured into a 1-mm-thick container and completely dried to removethe solvents. Then, an aqueous dispersion of FSNP-TiNSs (0.40wt%)was added into the container and left undisturbed for at least 12 h.Time-lapse CLSMwas performed at room temperature using a 460-nmlaser for giant vesicles and a 550-nm laser for the nanosheets (Sup-plementary Fig. 16 and Supplementary Movie 3).Magnetic orientation of multi-functional photonic crystalsTypically, aqueous dispersions of hybrid nanosheets (AuNP-TiNSs,AuNR-TiNSs, FSNP-TiNSs, and AuNR/FSNP-TiNSs) in a 1-mm-thickquartz cuvette (40 × 10 × 1mm) were placed in the bore of a super-conducting magnet, and a 12 T magnetic field was applied either per-pendicular or parallel to the cuvette surface at 70 °C for 30min. Afterair cooling to room temperature and removal of the magnetic field,observations and measurements were carried out (Figs. 4 and 5aand Supplementary Figs. 13, 14, 17–19). In Supplementary Fig. 18, theangle of the magnetic field with respect to the cuvette surface wasgradually changed from 90° to 40°. To achieve reversible switchingof optical properties (i.e., structural colors and plasmonicabsorption) as shown in Fig. 5b, this process was repeated at 50 °C forthree cycles, after changing the direction of the magnetic fieldeach time.Photo-induced modulation of structural colorAuNP-TiNSs were synthesized by slowly adding an aqueous dispersionof positively charged AuNPs (0.0045wt%, 3.0mL) to the TiNS disper-sion (0.050wt%, 10mL) under stirring at 500 rpm. The resultant dis-persion was subjected to two cycles of centrifugation at 20,000×g for20min and redispersion in water, resulting in a photonic crystal ofAuNP-TiNSs that exhibited a structural color. The photonic crystals ofAuNP-TiNSs (0.60wt%) and TiNSs (0.60wt%) were poured into 1-mm-thick quartz cuvettes (40 × 10 × 1mm) and placed in the bore of asuperconducting magnet. A 12 T magnetic field was applied perpen-dicular to the cuvette surface at 80 °C for 30min. After air cooling toroom temperature and removal of the magnetic field, observationsand measurements were carried out (Fig. 5c). The resultant photoniccrystals were irradiated with green LED light (a Thorlabs model SOLIS-525C high-power LED light; 525 nm, 3.1W) for 10min, followed by aircooling for 10min after the light was turned off. The photo-inducedtemperature changes were monitored using time-dependent thermalimages recordedwith a FLIR T530 thermal imaging camera. Thephoto-induced changes in the structural color of the AuNP-TiNS photoniccrystal (0.60wt%) were evaluated by UV-Vis spectroscopy before andafter each light irradiation.Data availabilityThe data that support the findings of this study are available within thepaper and its Supplementary Information. Additional data related tothe paper are available from the corresponding authors upon request.Source data are provided with this paper.References1. Ge, J. & Yin, Y. Responsive photonic crystals. Angew. Chem. Int. Ed.50, 1492–1522 (2011).2. Hou, X., Li, F., Song, Y. & Li, M. Recent progress in responsivestructural color. J. Phys. Chem. Lett. 13, 2885–2900 (2022).3. Liu, P. et al. Self-assembled colloidal arrays for structural color.Nanoscale Adv. 1, 1672–1685 (2019).4. Li, K., Li, C., Li, H., Li, M. & Song, Y. Designable structural colorationby colloidal particle assembly: From nature to artificial manu-facturing. iScience 24, 102121 (2021).5. Sun, J., Bhushan, B. & Tong, J. 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Y.E. and T.S. syn-thesized the aqueous dispersion of titanate nanosheets. S.Y. and K.S.analyzed the data and wrote the manuscript. All authors discussed theresults and commented on the manuscript. K.S. conceived, designed,and supervised the project.Competing interestsThe authors declare no competing interests.Additional informationSupplementary information The online version containssupplementary material available athttps://doi.org/10.1038/s41467-026-70456-6.Correspondence and requests for materials should be addressed toKoki Sano.Peer review information Nature Communications thanks Ling Bai,Dongpeng Yang, Tiancong Zhao, and the other, anonymous, reviewer(s)for their contribution to the peer review of this work. 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To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.© The Author(s) 2026Article https://doi.org/10.1038/s41467-026-70456-6Nature Communications |         (2026) 17:4517 12https://doi.org/10.1038/s41467-026-70456-6http://www.nature.com/reprintshttp://creativecommons.org/licenses/by/4.0/http://creativecommons.org/licenses/by/4.0/www.nature.com/naturecommunications Multi-functional photonic crystals of modular nanosheets Results Synthesis and characterization of hybrid nanosheets Magnetically induced orientation control of hybrid nanosheets Construction of multi-functional photonic crystals from hybrid nanosheets Three-dimensional structural characterization of multi-functional photonic crystals Optical control of multi-functional photonic crystals Discussion Methods General Materials Synthesis of positively charged gold nanoparticles Synthesis of positively charged gold nanorods Synthesis of hybrid nanosheets and construction of multi-functional photonic crystals Optical characterizations Small-angle X-ray scattering (SAXS) measurements Confocal laser scanning microscopy (CLSM) observations Magnetic orientation of multi-functional photonic crystals Photo-induced modulation of structural color Data availability References Acknowledgements Author contributions Competing interests Additional information