Controllable Preparation And Fluorescence Properties Of Noble Metal Nanoclusters Polymer Composites

With the rapid development of industrialization,the pollution caused by heavy metal ions to the environment seriously threatens human health.Currently,most of the methods of detecting heavy metal ions are complicated and costly.Among these methods,the detection of heavy metal ions by fluorescence-based nanosensors has attracted a great deal of attention due to their simplicity,high sensitivity and selectivity,and real-time detection.Stimuli-responsive materials are capable of exhibiting reversible or irreversible changes in their physical properties and/or chemical structures in response to small changes in the external environment(temperature,pH,ionic strength molecules and etc.).As a novel stimuli-responsive material,poly(N-isopropylacrylamide)(PNIPAM)exhibits construction changes at a lower critical solution temperature(LCST)of 32oC,and has been extensively studied.In this paper,we have designed and prepared a thermos-responsive photoluminescent hydrogel nanocomposites of Ag clusters/p(NIPAM-co-AAc)through photoreduction process,which is a simple,low-cost and environmentally friendly route.The hydrogel nanocomposites integrate the advantages of p(NIPAM-co-AAc)hydrogel submicron particles and Ag clusters: the p(NIPAM-co-AAc)hydrogel submicron particles can act as templates for Ag nanoclusters and exhibit thermo-responsive properties.Through the exploration,the optimum synthesis conditions are determined.The photoluminescence(PL)intensity of as-prepared nanocomposites exhibited a linear and reversible response from 2 to 85oC and displayed a high PL quenching for the sensitive and selective detection of Cr(VI).The limit of detection could reach as low as 1ppb,which is lower than the standard regulated by the U.S.Environmental Protection Agency(USEPA).In addition,inspiring by the hydrogel nanocomposites of Ag clusters/p(NIPAM-co-AAc),we have designed and synthesized a thermo-responsive macroscopical BSA-AuNCs/ hydrogel composite with excellent fluorescence properties,which displayed a near linear response from 0 to 80oC.Meanwhile,it will not affect the inherent properties by filling Au NCs into hydrogel.Therefore,This PL hydrogel composites hold a great promise for potential applications.