Recent Advances in Inorganic Chiral Nanomaterials

Abstract

handedness or LH) and d-sugars (only having right handedness or RH) with unknown reason. Such biological homochirality essentially governs asymmetric biochemical reactions with diverse physiological effects, and plays a paramount role in disease therapeutics and pharmaceutical production. [1] When bulk materials are shrunk to the nanometer scale, that is, the formation of nanomaterials or generally called nanoparticles (or NPs) that possess high surface areas and restrictly confine electron movement to remarkably induce a series of compelling chemical, catalytic, optical, plasmonic, (opto)electronic, magnetic, and mechanical properties. [2] Due to these unique properties, inorganic NPs have been developed to function as multifunctional platforms for biomedical applications (or bioapplications) in drug delivery, bioimaging, disease diagnosis, screening, and therapeutic treatments. [3] The homochirality-determined asymmetic biochemical activities and processes intrincially demand the fabrication of inorganic chiral nanomaterials, whose biofunctions fundamentally depend on the asymmetric interactions at nano-bio interfaces. [4] However, most inorganic compounds thermodynamically have achiral crystal structures, and metallic crystals usually have cubic or hexagonal symmetries. [5] Chiral driving forces are indispensably applied to impose chirality onto inorganic NPs, which have been reviewed previously. [6][7][8] Chiral driving forces include chirality transfer from chiral ligands, [9][10][11] chiral templates [12] (such as DNA, [13] proteins, [14] peptides, [15] cellulose nanocrystals, [16] liquid crystals modified with chiral ligands, [17] lipidic nanoribbons, [18] chiral mesoporous silica, [19] nanohelices [20,21] ), circularly polarized light (CPL), [22] spatially chiral arrangement using lithography techniques, [23] helical magnetic fields, [24] orbital angular momentum, [25] macroscopic asymmetric gradients of biaxial strain fields, [26] and macroscopic shear forces. [27,28] A pair of chiral objects are designated as enantiomorphs, and especially a pair of chiral molecules are called enantiomers. It is of fundamental importance to differentiate an enantiomorph from its stereoisomer (i.e., enantiodifferentiation or enantiodiscrimination), mainly through monitoring differential interactions with other chiral objects. The most compelling property of inorganic chiral NPs is optical activity (OA, or the chiroptical effect), denoting the differential interactions with LH and RH CPL (or LCP and RCP conventionally used). Chiral nanomaterials have the linear OA characterized with circular dichroism (CD, denoting the differential absorption) [29] Inorganic nanoparticles offer a multifunctional platform for biomedical applications in drug delivery, biosensing, bioimaging, disease diagnosis, screening, and therapies. Homochirality prevalently exists in biological systems composed of asymmetric biochemical activities and processes, so biomedical applications essentially favor the usage of inorganic chiral nanomaterials...

Chiral plasmonic nanostructures: recent advances in their synthesis and applications

“…25,63,111 However, it is the possibility of coupling chiral surface plasmons to the metamaterial environment that has driven the research to find applications mostly in molecular sensing, 223,224 enhanced spectroscopies, 225 non-linear chiroptics and chiral catalysis. 226…”

Mechanism of diastereoisomer-induced chirality of BiOBr

“…[17][18][19] The great potential of assembled chiral inorganics in optics, electricity, magnetism, biology, and chemistry has attracted tremendous interest in the chiral molecule-driven assembly of chiral inorganic nanostructures. [20][21][22][23][24] Although the chemical and physical chirality origins of inorganic nanostructures involving chiral crystal surfaces, [25][26][27][28] screw dislocation, [29][30][31] chiral imprinting, 32,33 and chiral geometries and assemblies induced by chemisorbed chiral molecules have been proposed, [13][14][15]34,35 chirality transfer from the molecular level to the macroscopic level of inorganic nanostructures across nanometers, micrometers and beyond is still not well understood. 36 Diastereoisomers with the same number of carbon chiral centers and functional groups but different R/S congurations and OAs would be the most noteworthy candidate molecules for studying the intriguing relationship between chiral molecular inducers and inorganic species.…”

“…17–19 The great potential of assembled chiral inorganics in optics, electricity, magnetism, biology, and chemistry has attracted tremendous interest in the chiral molecule-driven assembly of chiral inorganic nanostructures. 20–24…”

Endowing inorganic nanomaterials with circularly polarized luminescence

“…In practice, there are many critical reviews that specifically introduced chiral inorganic nanomaterials, but most of them focused on the optical activity at the ground state. [31][32][33][34][35] Comprehensive classification and summary of chirality at the excited state of inorganic nanomaterials are rarely mentioned. Understanding the relationship between chiral inorganic nanostructures and circularly polarized light will enrich the optical properties of these chiral nanomaterials and broaden the scope of their applications.…”