Plasmonic nanostructures acting as a light-driven O_(2)-sensitive nitroreductase mimic for enhanced photochemical oxidation of para-aminothiophenol

Nanozymes,as a novel form of enzyme mimics,have garnered considerable interest.Despite overcoming the main disadvantages of their natural analogs,they still face challenges such as restricted mimic types and low substrate specificity.Herein,we introduce a reactive ligand modification strategy to diversify enzyme mimic types.Specifically,we have utilized helical plasmonic nanorods(HPNRs)modified with para-nitrothiophenol(4-NTP)to create an oxygen-sensitive nitroreductase(NTR)with light-controllability.HPNRs act as a light-adjustable source of nicotinamide adenine dinucleotide/nicotinamide adenine dinucleotide phosphate(NAD(P)H),providing photon-generated energetic electrons to adsorbed 4-NTP molecules.In the presence of O_(2),the activated 4-NTP transfers the captured electron to the adsorbed O_(2),mimicking the electron transfer process in its natural counterpart.This enhanced O_(2)activation notably boosts the oxidative coupling of para-aminothiophenol(4-ATP).Density functional theory(DFT)calculations reveal that hot electrons injected into the lowest unoccupied molecular orbital(LUMO)energy level of 4-NTP can be transferred to that of molecular oxygen.In conclusion,our findings underline the potential of the reactive ligand modification strategy in developing new types of enzyme reactions,which opens up promising avenues for the enhancement and diversification of nanozyme functionalities.

Temperature-modulated inversion and switching of chiroptical responses in dynamic side-by-side oligomers of gold nanorods

Herein,a new strategy is proposed for achieving dynamic chiral controls in self-assembly systems of plasmonic nanorods based on temperature-modulation.Via enlarging Au{100}side facets of Au nanorod(AuNR)building block and changing surface ligand from often-used cetyltrimethylammonium bromide(CTAB)to cetylpyridinium chloride(CPC),inversion of chiroptical signal in side-by-side(SS)oligomers is realized.Under the guide of chiral cysteine(Cys),Au{100}side facet-linked SS rods twist in the opposite direction compared with Au{110}side facet-linked counterparts.At high CPC concentration,by controlling the incubation temperature of chiral Cys,the dominant twist mode can be regulated.Finite-difference time-domain(FDTD)simulations indicate the key role of the twisting dihedral angle of the oligomers in driving chiral signal inversion.At low CPC concentration,a temperature-sensitive chiral switching is observed owing to the conformation change of the CPC ligand layer.The temperature-modulated chiral responses are based on the interactions of chiral molecules,achiral surface ligands,and exposed facets of the building block.The rich dynamic tunability of chiroptical responses of plasmonic assemblies may find applications in stimulus-responsive nanodevices.

Dynamic cell transition and immune response landscapes of axolotl limb regeneration revealed by single-cell analysis

Dear Editor,The axolotl,Ambystoma mexicanum,has extraordinary capability to fully recover multiple tissues after lost,whereas such capability has disappeared in mammals.Thus,deci-phering detailed mechanisms underlying axolotl regenera-tion could provide valuable lessons for regenerative medicine.However,many questions,such as the origin of essential progenitor cells and key responses of individual types of cells for regeneration remain elusive(Haas and Whited,2017).Newly developed single-cell RNA sequenc-ing(scRNA-seq)method enables researchers to observe cellular and molecular dynamics in axolotl regeneration at the single-cell resolution(Gerber et al.,2018;Leigh et al.,2018),but the reported transcriptome landscapes are only for certain cell types or in certain regenerative stages.A complete overview of the regeneration process for all cell types is still lacking.