Chiral nanoparticle-induced amplification in optical activity of molecules with chiral centers

Sensitive differentiation of an enantiomer from its mirror image(ie,enantiodifferentiation),a perennial challenge for pharmaceutical production and disease diagnosis,is technically limited by the weak optical activity(OA)of enantiomers,mainly due to their dimensional mismatch with light wavelengths in the ultraviolet(UV)-visible region.Here we use silver chiral nanoparticles(Ag CNPs)with nominally sub-5 nm helical pitch(P)to amplify the OA of(20R,30R,40S)-riboflavin-50-phosphate sodium salts(RP),which have been found to indirectly affect metabolic processes,through the formation of an RP thin film(TF)covering a close-packed array of Ag CNPs.The OA of the RP in the deep-UV region can be amplified up to 80-fold,ascribed to the aggregation of RP in the TFs and the interactions between RP and the atomically chiral lattices at the CNPs'surfaces.The former contribution,not associated with the chiral Ag topographies,plays a dominant role by thickening the RP TFs,so that the observed amplification has no enantioselective dependence on the chirality of the Ag CNPs.This study extends progress in the sensitive detection of bio-enantiomers,which is highly desired for advanced bio-detection in disease diagnosis and production of single-enantiomer pharmaceuticals.

A chirality indicator for the walls and the surfaces of silica nanotubes

Single-handed helical silica nanotubes were prepared according to the literature procedures,using the self-assemblies of a pair of chiral cationic low-molecular-weight gelators as the templates.A chirality indicator,4,4＇-bis（triethoxysilyl）-1,1＇-biphenyl,was developed to determine the chirality of the silica nanotubes.The chirality of the surfaces and the bulky walls of the silica nanotubes were understood from the twist of the biphenylene rings.

Chiral CdSe/CdS quantum dot (in rod)-light-emitting diodes with circularly polarized electroluminescence

Chiral quantum dot(in rod)-light-emitting diodes(CQLEDs)with circularly polarized electroluminescence(CPEL)have driven interest in the future display,communication,and storage industries.However,the preparation of CQLEDs is still a challenging unresolved.Herein,we fabricated CQLEDs through spin-coating evaporation of chiral CdSe/CdS quantum rods(CCCQs)colloidal solution on indium tin oxide substrate.The CCCQs were synthesized via an isotropically epitaxial growth with cholic acid as the symmetry breaking agent,which induced one-direction chiral dislocation around the c axis of their hexagonal crystal structure.The CCCQs were ranked side-by-side in right-handed chiral arrangement with helical axis perpendicular to substrate due to chiral driving force of the cholic acid arrangement.The CQLEDs exhibited a negative CPEL signal at 600 nm with a|gEL|of 2×10^(−4),which is ascribable to the selective filtration on emission arising from the circular Bragg resonance by quasi-photonic crystal structures.

Effect of chirality on conformation and cellular uptake of poly(S-(o-nitrobenzyl)-L,D-cysteine) polypeptides

A series of poly（S-（o-nitrobenzyl）-L,D-cysteine） polypeptides with different chirality was synthesized and their molecular structures,secondary conformations,drug release and biological properties were thoroughly investigated.The chirality of the polypeptides had effect on secondary conformations and the cellular uptake behavior of the related nanoparticles.