Research On Synthesis And Detection Of Ratiometric Fluorescent Probe Based On Bimetallic Nanoparticles

Bimetallic nanoparticles(NPs)have been the subject of extensive study due to their stable optical properties,good synergy performance,and high biocompatibility.With their characteristic optical and catalytic properties enhanced by strong synergistic effects and influenced by variations in their precise composition,the bimetallic NPs have been explored the potential materials of composition ratio fluorescent probes.In this work,the bimetallic NPs were synthesized and explored corresponding fluorescent probe for detection of heavy metal ions such as Hg²⁺.And the ratiometric fluorescent probes composed by bimetallic NPs,Si NPs and Carbon dots(CDs)were also designed and explored.The bimetallic NPs based ratiometric fluorescent probes can be used as multi-functional probe for detection heavy metal ions with different fluorescent color.A dual-mode colorimetric and fluorimetric probe was successfully established based on silver/copper bimetallic nanoparticles(AgCu-BNPs).The AgCu-BNPs were confirmed as individually bimetallic nanoparticles with a mean size of 7.7±0.2 nm,as characterized by high resolution transmission electron microscopy.Intriguingly,the AgCu-BNPs possess both surface plasmon resonances(SPR)and fluorescence emission.AgCu-BNPs emanate bright blue fluorescence with optical emission centered at 442 nm with high quantum yield of 30.3%,and AgCu-BNPs were attenuated or even quenched by Hg²⁺via both static and dynamic quenching,coincidently accompanied by a visible color change,which endow AgCu-BNPs a unique utility as dual-mode colorimetric and fluorimetric probes.The detection limits as low as 89 nM and 9 nM were determined by dual-mode of AgCu-BNPs,respectively.The recovery rates in real samples were found to be 97.3-118.8%,and 89.5-112.7%by colorimetric and fluorescent methods separately,demonstrates the good environmental tolerance of the dual-mode probe.In addition,the application of AgCu-BNPs in catalysis is expanded,which can efficiently convert 4-NP to 4-AP within 180 s,and convert K3Fe(CN)6 to K4Fe(CN)6 within 120 s.Ratiometric fluorescent probe(BSA@AuAg-Si NPs)composed by the red luminescent bimetallic BSA@Au Ag nanoclusters(BSA@Au Ag NCs)and the blue luminescent Si NPs has been prepared with a quantum yield of 23.48%.It is worth noting that BSA@AuAg-Si NPs have good p H and ionic strength stability.The ratiometric fluorescent probe can be employed as a multi-functional probe to recognize Ag⁺,Cu²⁺and Hg²⁺ions with good selectivity and rapid response rate.The detection limits for Ag⁺,Cu²⁺and Hg²⁺are 2.109?M,1.092?M and 0.152?M,respectively.The mechanism of BSA@AuAg-Si NPs for multiple-detection of heavy metal ions was systematically explored.The ratiometric fluorescent probe was further applied to the Yalu River water samples for recovery testing.The recovery rate of Ag⁺ranges from92.3%to 107.4%,and the recovery of Cu²⁺is 92.5%?106.3%,and 93.6%?98.7%for Hg²⁺respectively.A kind of ratiometric fluorescent probe(BSA@AuAg-CDs)composed by red BSA@AuAg NCs and blue CDs by cross-links EDC/NHS was explored,which can be used to detect Cu²⁺and Hg²⁺ions with high selectivity and sensitivity.The fluorescence quantum yield of ratio fluorescent probe BSA@AuAg-CDs is 19.45%.The Cu²⁺and Hg²⁺can be distinguished by different fluorescent signal,the detection limits of the probe for Cu²⁺and Hg²⁺in aqueous solution are 0.579?M and 0.024?M,respectively.Due to the good stability and environmental adaptability of BSA@AuAg-CDs,the recovery rates of Cu²⁺and Hg²⁺in the Yalu River water samples of the ratiometric fluorescent probe are in the range of 99.0%?110.1%and 92.7%?108.8%,respectively.