Synthesis And Application Of Functionalized Copper Nanocluster Composites

Nanomaterials have been recognized as one of the most promising research topics in recent years,especially,metal nanoclusters have aroused immense interest among researchers due to their excellent photostability,large Stokes shift,and low environmental hazard.To date,noble metal?mainly Au and Ag?nanoclusters are widely applied in the field of analysis and detection based on their chemical stability and facile synthetic procedure,however,the promising copper nanoclusters?CuNCs?has received less attention.Although CuNCs have many advantages,such as relatively abundant,inexpensive,easy availability,and various kinds of the precursors,etc.,the poor stability and easy oxidation limit the various applications of them.Based on the functionalized CuNCs/nanocomposites,the following research works were carried out in this paper:1.Eu³⁺-doped CuNCs was synthesized to solve the poor stability of pure CuNCs which was protected by glutathione?GSH?and low sensitivity of their ECL assays.Eu³⁺ion could alter the surfaces of CuNCs and then drive the formation of new surface state?Eu?III?complex?to promote effective energy transfer from the host to the Eu³⁺ion,resulting in greatly enhanced ECL emission intensity and stability of CuNCs.An ECL biosensor based on Eu³⁺-doped CuNCs was fabricated for bioanalysis,taking the detection of dopamine?DA?as a model system,which achieved a minimum detection concentration of 0.01 nM.In addition,the assay showed a strong selectivity to target substance.The presented results give us a clue to solve the stability issues of CuNCs,provide a powerful tool for the developing ECL emitters,and may open the promising avenues to develop new ECL systems for medical and biological analysis.2.The superior sensing performance of Hg?II?using nanocomposite based on carbon nitride nanosheets?CNNS?and CuNCs functionalized by dithiothreitol?DTT?was demonstrated,which not only stabilized the nanoclusters,but also improved the sensitivity of Hg?II?detection.The ECL mechanism is related to the reaction of the DTT-CuNCs/CNNS nanocomposite with K₂S₂O₈ in the electrochemical system,while the presence of Hg?II?leads to quenching of its excited state,and the suppression of the formation of anion-radicals.The Hg?II?sensor presented here is cheap and fast,and shows high selectivity for the detection of Hg?II?on the background of other mono-,di-,and trivalent ions,with a linear range of 0.5¹0 nM and the minimum detection concentration as low as0.01 nM.3.CuNCs,in which cysteine?Cys?served as both a reducing agent and a protection ligand,was synthesized,and then impregnated into a nanogel of glycol chitosan?GC?,forming the CuNCs@GC nanocomposite.The stability of CuNCs incorporated into a nanogel was significantly improved,while their photoluminescence?PL?intensity of CuNCs@GC could be tuned by controlling the pH of the system.The nanocomposite was used as a platform for the“turn on”detection of Zn²⁺,making use of the effect of aggregation induced emission?AIE?enhancement.Adjusting the pH of the system to 7.4,CuNCs@GC system had the weakest PL intensity and the smallest background signal.In the presence of Zn²⁺,the nanoclusters in CuNCs@GC changed from the dispersed state to the aggregated state,which resulted in an increase of the PL intensity.A linear response between the PL intensity and the concentration of Zn²⁺,in the range from 1.5?M to 750?M,was obtained,achieving a detection limit?LOD?of 1.0???S/N=3?.Furthermore,the CuNCs@GC nanocomposite was found to be applicable to live cell imaging,owing to the high biocompatibility and protective effects of GC.4.Based on the encapsulation of CuNCs mixed with Al³⁺into a zeolitic imidazole framework-90?ZIF-90?to form CuNCs-Al³⁺/ZIF-90 nanocomposite,a novel,simple and sensitive fluorescent sensor was developed to detect adenosine triphosphate?ATP?and then evaluate the freshness of aquatic products by determining the changes in the level of ATP.Encapsulated CuNCs could be released from the ZIF-90 after their addition to ATP,resulting in the fluorescence quenching of this system.Based on this phenomenon,the sensitive detection of ATP was realized with a LOD of 0.67???S/N=3?,and a good linear relationship was observed between the fluorescence quenching ratios of the CuNCs-Al³⁺/ZIF-90 nanocomposite and ATP in the concentration range from1 to 2000?M.Moreover,satisfactory results were obtained when the proposed ATP detection method was applied to real samples to evaluate the freshness of aquatic products.