The synthesis of fluorescent nanoclusters based on the etching reaction

Thiolate-protected atomically precise nanoclusters(NCs)demonstrate a series of unique luminescent characteristics attributed to their various peculiar electronic structures.Therefore,fluorescent NCs present extraordinary practical values in biosensing and bioimaging research fields.Nevertheless,restricted by the types of fluorescent NCs,there are great difficulties in promoting the development of NCs in fluorescent research areas.As a result,it is of significant necessity for researchers to develop new synthetic pathways to produce high-quality fluorescent NCs.According to the analysis about the structural characteristics of fluorescent NCs,some general features like longer motif and higher ligand-to-metal ratio can be found,consistent to some presented regularities in etching reaction.Consequently,in this work,we used Au_(25)(MHA)_(18)(MHA=6-mercaptohexanoic acid)as a model nanocluster and utilized the etching reaction to systematically explore etching products and their corresponding luminescent properties.Moreover,we also identified three main reaction processes in the entire etching reaction process,which can generate new metal nanocluster species with various fluorescent properties.Hence,the etching reaction will provide a good platform to produce new luminescent metal NC species.

Ligand-dependent aggregation-enhanced photoacoustic of atomically precise metal nanocluster

Atomically precise metal nanoclusters(MNCs),as a potential type of photoacoustic(PA)contrast agent,are limited in application due to their low PA conversion efficiency(PACE).Here,with hydrophilic Au25SR18(SR=thiolate)as model NCs,we present a result that weakly polar solvent induces aggregation,which effectively enhances PA intensity and PACE.The PA intensity and PACE are highly dependent on the degree of aggregation,while the aggregation-enhanced PA intensity(AEPA)positively correlates to the protected ligands.Such an AEPA phenomenon indicates that aggregation actually accelerates the intramolecular motion of Au NCs,and enlarges the proportion of excited state energy dissipated through vibrational relaxation.This result conflicts with the restriction of intramolecular motion mechanism of aggregation-induced emission.Further experiments show that the increased energy of AEPA originates from the aggregation inhibiting the intermolecular energy transfer from excited Au NCs to their surrounding medium molecules,including solvent molecule and dissolved oxygen,rather than restricting radiative relaxations.This study develops a new strategy for enhancing the PA intensity of Au NCs,and contributes to a deeper understanding of the origin of the PA signal and the excited state energy dissipation processes for MNCs.

Identification of chemical compositions from“featureless”optical absorption spectra:Machine learning predictions and experimental validations

Rapid and accurate chemical composition identification is critically important in chemistry.While it can be achieved with optical absorption spectrometry by comparing the experimental spectra with the reference data when the chemical compositions are simple,such application is limited in more complicated scenarios especially in nano-scale research.This is due to the difficulties in identifying optical absorption peaks(i.e.,from“featureless”spectra)arose from the complexity.In this work,using the ultraviolet-visible(UV-Vis)absorption spectra of metal nanoclusters(NCs)as a demonstration,we develop a machine-learningbased method to unravel the compositions of metal NCs behind the“featureless”spectra.By implementing a one-dimensional convolutional neural network,good matches between prediction results and experimental results and low mean absolute error values are achieved on these optical absorption spectra that human cannot interpret.This work opens a door for the identification of nanomaterials at molecular precision from their optical properties,paving the way to rapid and high-throughput characterizations.

Hierarchical TiO2-B nanowire@α-Fe2O3 nanothorn core-branch arrays as superior electrodes for lithium-ion microbatteries

这份报纸为层次 TiO 的合成报导一个简单还有效的方法 < 潜水艇 class= “ a-plus-plus ” > 2 -B nanowire@-Fe < 潜水艇 class= “ a-plus-plus ” > 2 O < 潜水艇 class= “ a-plus-plus ” > 3 nanothorn 核心分支基于一条逐步的热水的途径穿。同样制作的混合数组为锂离子电池作为高能力的阳极显示出出色的性能。在这研究的关键设计是核心分支混血儿体系结构，它提供大表面不仅为锂离子插入 / 抽取的活跃地点，而且为电子和锂离子由于减少的散开路径启用快费用运输。 TiO 的属性的古怪联合<潜水艇class=“ a-plus-plus ”> 2 (好结构的稳定性)和 Fe <潜水艇class=“ a-plus-plus ”> 2 O <潜水艇class=“ a-plus-plus ”> 3 (大特定的能力)向混合数组电极提供几理想电气化学的特征：大可逆能力(800 mAstalline 和大区域瞬间 < 潜水艇 class= “ a-plus-plus ” > 由化学蒸汽免职方法的 2 层。先锋的数量的小心的控制在大区域的合成被发现到关键因素高度水晶的薄片。层的厚度被拉曼光谱学和原子力量显微镜学证实。光性质和化学作文被光致发光(PL ) 和 X 光检查光电子光谱学学习。在 1.82 eV 的强壮的直接激子的排出物的出现(A 激子，与规范的 PL i 械 ? 械？？

Embedding ultrasmall Ag nanoclusters in Luria-Bertani extract via light irradiation for enhanced antibacterial activity

Ultrasmall silver nanoclusters(Ag NCs)with rich surface chemistry and good biocompatibility are promising in antibacterial application,however,further development of Ag NCs for practical settings has been constrained by their relatively weak antibacterial activity.Using the nutritionally-rich medium for bacteria(e.g.,Luria-Bertani(LB)medium)to coat active Ag NCs could further improve their antibacterial activity.Here,we provide a delicate design of a highly efficient Ag NCs@ELB antibacterial agent(ELB denotes the extract of LB medium)by anchoring Ag NCs inside the ELB species via light irradiation.The as-designed Ag NCs with bacterium-favored nutrients on the surface can be easily swallowed by the bacteria,boosting the production of the intracellular reactive oxygen species(ROS,about 2-fold of that in the pristine Ag NCs).Subsequently,a higher concentration of ROS generated in Ag NCs@ELB leads to enhanced antibacterial activity,and enables to reduce the colony forming units(CFU)of both gram-positive and gram-negative bacteria with 3–4 orders of magnitude less than that treated with the pristine Ag NCs.In addition,the Ag NCs@ELB also shows good biocompatibility.This study suggests that surface engineering of active species(e.g.,Ag NCs)with nutritionally-rich medium of the bacteria is an efficient way to improve their antibacterial activity.

Luminescent metal nanoclusters:Biosensing strategies and bioimaging applications

Metal nanoclusters(MNCs)are ultrasmall metal-organic aggregates,composed of a metal core less than 2 nm and a protecting shell of metal-organic ligand motifs.The controlled aggregation of metal atoms(in the cluster core)and metal-organic ligand motifs(around the cluster core)renders MNCs with numerous molecule-like properties,among which strong and bright luminescence has attracted extensive basic and applied interests.It has now known that aggregation-induced emission is a feasible mechanism for controlling luminescence of MNCs,which makes it particularly useful in biosensing and bioimaging applications.Although the luminescence fundamentals and design principles largely determine the practicality and effectiveness of MNCs in biosensing and bioimaging applications,a systematic summary of this topic is lacking in the current literature.In this review,we aim to provide a concise discussion of the latest developments in biosensing and bioimaging applications of luminescent MNCs,highlighting their luminescence mechanisms,biosensing principles,and bioimaging strategies.Specifically,we first introduce the recent advances in the synthetic chemistry of MNCs,and then briefly discuss the luminescence fundamentals ofMNCs.Then the design strategy and practicality of luminescent MNCs in biosensing and bioimaging applications are exemplified.We conclude the review with our perspectives on the further development of MNC-based optical probes in biosensing and bioimaging applications.Our review is expected to provide guidance for the future practice of designing and synthesizing luminescent MNCs for biomedical and other applications.

Converting ultrafine silver nanoclusters to monodisperse silver sulfide nanoparticles via a reversible phase transfer protocol

To achieve better control of the formation of silver sulfide （Ag2S） nanoparticles, ultrasmall Ag nanoclusters protected by thiolate ligands （Ag44（SR）30 and Agla（GSH）9） are used as precursors, which, via delicate chemistry, can be readily converted to monodisperse Ag2S nanoparticles with controllable sizes （4-16 nm） and switchable solvent affinity （between aqueous and organic solvents）. This new synthetic protocol makes use of the atomic monodispersity and rich surface chemistry of Ag nanoclusters and a novel two-phase protocol design, which results in a well-controlled reaction environment for the formation of Ag2S nanopartides.