Preparation Of Multifunctional Metallothionein-stabilized Copper Nanoclusters And Its Application In Analytical Detection

Copper nanoclusters?CuNCs?are a new type of practical nanomaterials with excellent properties and are highly economic.At present,the process of preparing high-quality copper nanoclusters is difficult and more challenging than that of noble metal nanoclusters because copper is easily oxidized in air,thus affecting the stability of CuNCs.Moreover,a majority of the prepared CuNCs have disadvantages such as poor dispersion properties,low quantum yield,and poor functionality,rendering them inadequate in meeting the needs of many applications.Therefore,there is a pressing need to develop a simple method to prepare multifunctional CuNCs and its related applied research.In chapter 1,a brief description of the significance of preparing multifunctional copper nanoclusters,and the leading synthesis methods and applications of copper nanoclusters have been outlined,in addition to a brief introduction about this article.Chapter 2 discusses the preparation of metallothionein-stabilized CuNCs?MT-CuNCs?using metallothionein as a stable template and reductant.The materials have been characterized by many techniques,followed by the verification of their versatility.The MT-CuNCs have stable luminescent properties,artificial enzyme activity,strong antioxidant capacity,and exhibit great application potential.In chapter 3,we discuss the fluorescence of MT-CuNCs and their quenching by lead ions.A new Pb²⁺assay based on photoluminescence property of MT-CuNCs was established and the quenching mechanism has been discussed.In a system containing Pb²⁺,MT-CuNCs interacts with Pb²⁺to form a non-fluorescent complex,resulting in a significant decrease in fluorescence.The?F of the system linearly responded to Pb²⁺concentrations in the range of?2.52¹20?×10^-77 mol/L and the detection limit was 8.4×10^-88 mol/L.The method is simple,low cost and easy to access.In chapter 4,we evaluate the catalase-like activity of MT-CuNCs toward 3,3',5,5'-tetramethylbenzidine?TMB?to change to a peroxidase-like activity in the presence of either Pb?II?or Hg?II?.When Pb?II?or Hg?II?was added,a weakened inhibitory effect of MT-CuNCs on the chromogenic reaction of TMB with H₂O₂ was observed,while the catalytic effect of the nanoclusters on the chromogenic reaction increased.Following Michaelis-Menten kinetics,the system MT-CuNCs-Pb²⁺/Hg²⁺exhibited high affinity for the substrates TMB and H₂O₂.Based on these findings,a method was developed for visual detection?via the formation of blue color?and spectrophotometric determination of Pb?II?and Hg?II?.The method is simple and feasible with good selectivity and wide linear range.The detection limits are 142 nM for Pb?II?and 43.8 nM for Hg?II?.In chapter 5,a new method for the detection of uric acid is discussed based on the peroxidase-like activity of metallothionein-stabilized copper nanoclusters,developed by using 3,3-diamino-biphenylamine?DAB?as a substrate.Uric acid oxidase specifically catalyzes the oxidation of uric acid to produce H₂O₂.MT-CuNCs have peroxidase-like activity and can catalyze the formation of·OH from H₂O₂ on their surface.The·OH with a strong oxidizing property oxidizes DAB to form brown DBTD aggregates.Here,within a certain concentration range,the uric acid concentration was quantitatively determined by measuring the color intensity of the system or the change in absorbance at 465 nm.This method can visually detect the concentration of uric acid in the blood and meet the clinical application requirements with the detection limit of7.72×10^-66 mol/L.