The density of surface ligands regulates the luminescence of thiolated gold nanoclusters and their metal ion response

The fascinating luminescence properties of gold nanoclusters(AuNCs) have drawn considerable research interests,and been widely harnessed for a wide range of applications.However,a fundamental understanding towards ligand density’s role in the luminescence properties of these ultrasmall AuNCs remains unclear yet.In this communication,through systematic investigation of surface chemistries of glutathione-protected Au NCs(GSH-Au NCs) with diffe rent density of GSH as well as other thiolates,it is discovered that the density of surface ligands can significantly regulate the luminescence properties of AuNCs.Fluorescence lifetime spectroscopy and X-ray photoelectron spectroscopy showed that AuNCs with a higher density of electron-rich ligands facilitate their luminescence generation.Moreover,differences in the surface coverage of AuNCs can also affect their interactions with foreign species,as illustrated by significantly different fluorescence quenching capability of GSH-AuNCs with different ligand density towards Hg^(2+).This study provides new insight into the intriguing luminescence properties of metal NCs,which is hoped to stimulate further research on the design of metal NCs with strong luminescence and sensitive/specific responses for promising optoelectronic,sensing and imaging applications.

Upconversion nanorods anchored metal-organic frameworks via hierarchical and dynamic assembly for synergistic therapy

Heterogeneous materials made of metal-organic frameworks(MOFs)and optically active nanomaterials have attracted intensive interests in recent years due to their distinct physicochemical properties,but controllable fabrication of these materials remains challenging yet.In this work,we report a new strategy to in situ fabricate heterogeneous nanomaterials based on UiO-66-NH2 and upconversion nanorods(UCNRs)via a hierarchical and dynamic assembly process.Core–satellite structured UiO-66-NH2@UCNRs have been successfully fabricated,and the formation mechanism was thoroughly investigated by the combined use of scanning electron microscopy(SEM)and Fourier transform infrared(FTIR)spectroscopy.Our results revealed the involvement of three main stages:supramolecular assembly of UiO-66-NH2 precursors with UCNRs,nucleation and growth of UiO-66-NH2 crystal,and dynamic assembly with UCNRs accompanied by Ostwald ripening.Furthermore,based on the hereditary optical and porous features of the heterogeneous nanomaterials,an enhanced multimodal synergistic anticancer platform has been established by integrating near-infrared(NIR)-triggered photodynamic therapy(PDT)and pH-triggered anticancer drug delivery,as confirmed by cellular experiments.The present study provides a new avenue for developing advanced functional heterogeneous nanomaterials via the hierarchical and dynamic assembly strategy.