Recent Advances of Persistent Luminescence Nanoparticles in Bioapplications

Persistent luminescence phosphors are a novel group of promising luminescent materials with afterglow properties after the stoppage of excitation.In the past decade,persistent luminescence nanoparticles(PLNPs)with intriguing optical properties have attracted a wide range of attention in various areas.Especially in recent years,the development and applications in biomedical fields have been widely explored.Owing to the efficient elimination of the autofluorescence interferences from biotissues and the ultra-long near-infrared afterglow emission,many researches have focused on the manipulation of PLNPs in biosensing,cell tracking,bioimaging and cancer therapy.These achievements stimulated the growing interest in designing new types of PLNPs with desired superior characteristics and multiple functions.In this review,we summarize the works on synthesis methods,bioapplications,biomembrane modification and biosafety of PLNPs and highlight the recent advances in biosensing,imaging and imaging-guided therapy.We further discuss the new types of PLNPs as a newly emerged class of functional biomaterials for multiple applications.Finally,the remaining problems and challenges are discussed with suggestions and prospects for potential future directions in the biomedical applications.

Kinetically regulated one-pot synthesis of cationic gold nanoparticles and their size-dependent antibacterial mechanism

Cationic gold nanoparticles(cAuNPs)have been regarded as promising candidates for antibacterial applications due to their high surface charge density,favorable biocompatibility,and controllable surface chemistry.Nevertheless,the complicated fabrication process and unclear antibacterial mechanism have greatly hindered the further biomedical application of cAuNPs.Herein,we have developed a simple and controllable strategy for synthesizing cAuNPs with tailored size and antibacterial behavior by kinetically modulating the reaction process.Specifically,a functional ligand,(11-mercaptoundecyl)-N,N,Ntrimethylammonium bromide(MUTAB),was chosen to chemically manipulate the positive surface charge of cAuNPs via a one-step strategy.The size of cAuNPs could be flexibly adjusted from 1.1 to 14.8 nm by simply elevating the stirring speed of the reaction from 0 to 1500 rpm.Further studies revealed that the antibacterial effect of cAuNPs was strongly correlated with the particle size.MUTAB-protected ultrasmall gold nanoclusters(MUTAB-AuNCs)were able to eradicate E.coli at a concentration as low as 1.25μg mL^(-1),while the minimum inhibitory concentration of MUTAB-AuNPs with a large size for E.coli was 5μg mL^(-1).Mechanistic investigation revealed that MUTAB-AuNPs were able to damage the bacterial membrane and stimulate the production of reactive oxygen species more effectively than MUTAB-AuNCs.Conversely,MUTAB-AuNCs were more active in inducing membrane depolarization in contrast to MUTAB-AuNPs,suggesting the unique size-dependent antibacterial manner of cAuNPs.This study presents a new strategy for the controlled preparation of cAuNPs with distinct sizes and antibacterial behavior,laying a valuable foundation for developing efficient cationic NP-based bactericidal agents.

Cationic antibacterial metal nanoclusters with traceable capability for fluorescent imaging the nano–bio interactions

A thorough understanding of antimicrobial mechanism is of great importance for developing novel,efficient antibacterial agents.While cationic nanoparticles,such as metal nanoclusters(NCs),represent an attractive type of antibacterial nanoagents,their interactions with bacteria remains largely un-elucidated.Herein,we report the synthesis of cationic bovine serum albuminprotected AuAgNCs(cBSA-AuAgNCs),which exhibit both near-infrared(NIR)fluorescence properties and significant antimicrobial effects.With E.coli and S.aureus as the representative bacteria,we investigated the antimicrobial process of cBSAAuAgNCs in real-time based on their intrinsic fluorescence properties via fluorescence imaging.Our results showed that these cBSA-AuAgNCs exert their antimicrobial effects primarily by attaching on the outer membrane of bacteria without obvious internalization,which is significantly different from the antibacterial process of negatively-charged metal NCs.Further mechanistic investigation showed that these cationic NCs will cause serious disruption to the bacterial membrane due to strong electrostatic interactions,which then leads to over accumulation of reactive oxygen species(ROS)that finally causes the bactericidal action.This study demonstrates the great potential of cationic luminescent metal NCs as novel,traceable antimicrobial agents,which also provides new tools for further understanding microbial interactions of nanomedicines.

Detection of amyloid-beta by Fmoc-KLVFF self-assembled fluorescent nanoparticles for Alzheimer’s disease diagnosis

The abnormal aggregation of amyloid-beta(Aβ)has been widely believed to play an important role in the pathogenesis of Alz heimer’s disease(AD),which is also recognized as one of the main biomarkers for AD diagnosis.The peptide sequence Lys-Leu-Val-Phe-Phe(KLVFF)is considered as the main driver of the fibrillation of Aβ,which also can be utilized to target Aβand inhibit its aggregation.In this study,KLVFF and Fmoc-KLVFF fluorescent nanoparticles were self-assembled through zinc coordination andπ-πstacking.The recognition of Aβaggregates including oligomers and fibrils by fluorescent nanoparticles can be realized through aromatic,hydrophobic,and hydrogen-bond interactions.The fluorescent nanoprobes can distinguish Aβaggregation formats and detect Aβat the limit of 1 pg/mL(S/N=3).Hence,the detection of Aβaggregates by fluorescent peptide nanoparticles has great potential for AD diagnosis and progression prediction.

Self-assembled fluorescent tripeptide nanoparticles for bioimaging and drug delivery applications

Peptide self-assembled nanomaterials have attracted more and more attention due to their wide applications such as drug delive ry,cell imaging,and real-time drug monitoring.However,the application of the peptide is still limited by its inherent optical properties.Here we proposed and prepared a series of fluorescent tripeptide nanoparticles(TPNPs)through π-π stacking and zinc coordination.The experimental results show that the nanoparticles(TPNPs1)formed by the self-assembly of the tripeptide tryptophan-tryptophan-tryptophan have the highest fluorescence intensity,uniform and appropriate size,and low cytotoxicity.Furthermore,there was fluorescence resonance between TPNPs1 and doxorubicin,which has been successfully applied for real-time cell imaging and drug release monitoring.

Design of active and stable catalysts by embedding nitrogen-doped carbon oxygen reduction reaction CoxOy nanoparticles into

The oxygen reduction reaction （ORR） is essential in research pertaining to life science and energy. In applications, platinum-based catalysts give ideal reactivity, but, in practice, are often subject to high costs and poor stability. Some costefficient transition metal oxides have exhibited excellent ORR reactivity, but the stability and durability of such alternative catalyst materials pose serious challenges. Here, we present a facile method to fabricate uniform CoxOy nanoparticles and embed them into N-doped carbon, which results in a composite of extraordinary stability and durability, while maintaining its high reactivity. The half-wave potential shows a negative shift of only 21 mV after 10,000 cycles, only one third of that observed for Pt/C （63 mV）. Furthermore, after 100,000 s testing at a constant potential, the current decreases by only 17%, significantly less than for Pt/C （35%）. The exceptional stability and durability results from the system architecture, which comprises a thin carbon shell that prevents agglomeration of the CoxOy nanoparticles and their detaching from the substrate.