Circularly Polarized Light-Enabled Chiral Nanomaterials: From Fabrication to Application

Abstract

For decades, chiral nanomaterials have been extensively studied because of their extraordinary properties. Chiral nanostructures have attracted a lot of interest because of their potential applications including biosensing, asymmetric catalysis, optical devices, and negative index materials. Circularly polarized light (CPL) is the most attractive source for chirality owing to its high availability, and now it has been used as a chiral source for the preparation of chiral matter. In this review, the recent progress in the field of CPL-enabled chiral nanomaterials is summarized. Firstly, the recent advancements in the fabrication of chiral materials using circularly polarized light are described, focusing on the unique strategies. Secondly, an overview of the potential applications of chiral nanomaterials driven by CPL is provided, with a particular emphasis on biosensing, catalysis, and phototherapy. Finally, a perspective on the challenges in the field of CPL-enabled chiral nanomaterials is given.

Keywords: Application; Chiral; Circularly polarized light; Fabrication; Nanomaterials.

Fig. 1

a Scheme of the glancing angle deposition (GLAD). b TEM image and c CD spectra of the chiral Al nanostructures prepared by GLAD (reproduced with permission from Ref. [40]. Copyright 2013, Wiley). d Scheme of the wet-chemical method to synthesize chiral HgS nanostructures. This method could allow the large-scale and cost-effective preparation of chiral nanostructures. e TEM image and f CD spectra of the chiral HgS nanostructures. Scale bar, 100 nm (reproduced with permission from Ref. [42]. Copyright 2017, Nature publishing group)

Fig. 2

a, b Circularly polarized light triggered enantioselective thiol–ene polymerization reaction. a Schematic illustration of the growing optically active polymer from racemic monomers through the asymmetric thiol–ene polymerization process triggered by 313 nm CPL irradiation. b CD signals (irradiation for 90 min) of the specific rotation values of the final polymer obtained by irradiation with 313 nm (i) LCP, (ii) RCP, or (iii) normal UV light (reproduced with permission from Ref. [66]. Copyright 2017 the Royal Society of Chemistry). c, d CPL to regulate azobenzene supramolecular chirality. c Scheme of long- and short-axis-dependent twisted stack led by wavelength-dependent LCP and RCP light. d CD and UV–Vis spectra of PAzoMA 2 aggregates exposed to 365 nm LCP and RCP light for 150 s (reproduced with permission from Ref. [68]. Copyright 2017 the Royal Society of Chemistry)

Scheme 1

Experimental setup for CPL-driven synthesis. a CPL irradiation apparatus: (i) light source, (ii) polarizer, (iii) quarter wave plate, (iv) cuvette as reaction container. b CPL was used to drive the assembly of monodisperse nanoparticles into chiral helixes. c CPL was used to fabricate chiral inorganic nanostructures

Fig. 3

Morphology and spectroscopy of CPL-mediated chiral gold nanostructures. Scanning electron microscope (SEM) images a, circular dichroism spectra b and g-factor spectra c of L-P+ NPs after 0, 5, 10, 20, 30, and 40 min of illumination at 594 nm with 84 mW cm−2. d SEM images of L-P+ NPs and D-P− NPs. e TEM tomography images of L-P+, L-P−, D-P−, and L-P0 NPs. Circular dichroism spectra f and g-factor spectra g of NPs synthesized under different light conditions in the presence of CYP dipeptides: L-P+ NPs (under LCP illumination), D-P− NPs (under RCP illumination), D-P+ NPs (under LCP illumination), L-P− NPs (under RCP illumination), L-P0 NPs (under LP illumination), D-P.0 NPs (under LP illumination), L-NPs (without light illumination), and D-NPs (without light illumination) (reproduced with permission from Ref. [79]. Copyright 2022 Nature publishing group)

Fig. 4

a TEM images and b of the chiral LH and RH AuNPs, which were prepared under the irradiation of LCP and RCP light, respectively (reproduced with permission from Ref. [81]. Copyright 2019 American Chemical Society). c SEM images of the chiral LH and RH Au-PbO2 nanostructures. d CD spectra of the TiO2 substrate with gold nanocuboids before (black line) and after PbO2 deposition by RCP (blue line) or LCP (red line) light irradiation (reproduced with permission from Ref. [82]. Copyright 2018 American Chemical Society)

Fig. 5

a–c Chiral GNR dimers and the asymmetric interactions with CPL. a Schematic illustrating the chiral GNR dimers with opposite handedness under illumination of CPL. b Typical SEM image of the GNR dimers. c g-factor spectra acquired from the GNR dimers under LCP or RCP light illuminations for 40 min (dashed lines) and 6 h (solid lines), respectively. LCP or RCP light was irradiated from a diode laser with a wavelength of 633 nm and a power density in the range of 50–90 mW cm⁻². (reproduced with permission from Ref. [3]. Copyright 2019, WILEY–VCH GmbH). d Illustration of the co-gel formation and its CPL responsiveness. e SEM image of the L-(Gel + FeS₂. f CD spectra of the L-(Gel + FeS₂) under LCP light illumination for 2, 4, 8, and 12 h (reproduced with permission from Ref. [84]. Copyright 2019, WILEY–VCH GmbH)

Fig. 6

a Schematic illustration of the Au NR@Pt dimer-UCNP satellites for intracellular triple-ion detection. b CD spectra of the Au NR@Pt dimer-UCNP satellites, and the inset is the typical TEM image of the Au NR@Pt dimer-UCNP satellites. c Normalized fluorescence intensity of satellite assemblies with various concentrations of the Cu2+, Zn2+, and Mg.2+ ions (reproduced with permission from Ref. [86]. Copyright 2019, WILEY–VCH GmbH). d Schematic illustration of the chiral CdTe NPs for combating gram-negative bacteria under CPL illumination. e CD spectra of the CdTe NPs and the CdTe NRs, and the inset is the typical TEM image of CdTe NP and NR. f Cell viability of E. coli incubated with chiral CdTe NPs and then treated with different illumination intensities (405 nm, 30 min). The inset is the TEM image of the E. coli after treating with chiral CdTe NPs and CPL (reproduced with permission from Ref. [89]. Copyright 2018, WILEY–VCH GmbH)

Fig. 7

a Schematic illustration of chiral CdTe-based specific DNA cleavage under CPL irradiation. b CD spectra of the chiral CdTe NPs (reproduced with permission from Ref. [88]. Copyright 2018 Nature publishing group). c Schematic illumination of the photocatalytic reduction of 4-nitrophenol by chiral Gold-Gap-Silver (GGS) nanostructures (NS). d CD spectra of GGS nanostructures prepared at different reaction times (reproduced with permission from Ref. [90]. Copyright 2015, WILEY–VCH GmbH). e Schematic illumination of photocatalytic oxidation of glucose enantiomers by chiral AuNP film. f CD spectra of the chiral AuNP films (reproduced with permission from Ref. [92]. Copyright 2018, WILEY–VCH GmbH)

Fig. 8

a Schematic of differentiation of NSCs with CPL after daily incubation with C30(D)S5-C20(L) for five days. b CD spectra of C30(D)S5-C20(L) and C30(D)-C20(L)S5 in phosphate buffered saline. c Neurite mean length of differentiated NSCs incubated with C30(D)S5-C20(L) or C30(D)-C20(L)S5 for 4 h each day, and subsequently illuminated with CPL (50 μJ per pulse, 50 Hz, 5 min) for five days, or incubated with C30(D)S5-C20(L) without illumination for 5 days; cells without nanoassemblies or light exposure were used as a control. d Mean lengths of neurites in differentiated NSCs. e CD spectra of differentiated NSCs from day 1 to day 5 (reproduced with permission from Ref. [93]. Copyright 2021 Nature publishing group). f CD spectra of Au NP film and L/D-Pen modified Au NP film. g Cell detachment rates upon different light irradiation (reproduced with permission from Ref. [94]. Copyright 2017 Nature publishing group)

Fig. 9

a Illustration of self-assembled shell–satellite (SS) nanostructure as a chiral photodynamic therapy agent under CPL illustration. b CD spectra of the chiral SS15 nanostructure. The inset is the 3D tomography of the SS15 nanoassembly. c The relative tumor growth curves after various treatments: PBS only, SS15 assembly + LCP light, SS15 assembly + LP light, and SS15 assembly + RCP light (reproduced with permission from Ref. [96]. Copyright 2017, WILEY–VCH GmbH). d Scheme for the synthesis of Cys-MoO3−x NPs and their applications for tumor cell ablation via CPL radiation. e CD spectra of chiral Cys-MoO3−x NPs. f Viability of HeLa cell incubating with chiral D-Cys-MoO2 (50 µg mL−1) after 532 nm RCP, LP, and LCP irradiation (1 W cm.−2 for 15 min) was analyzed by CCK-8 assay (reproduced with permission from Ref. [97]. Copyright 2019, WILEY–VCH GmbH)