Preparation And Applications Of Nanoclusters Based On Cysteine Proteases As Templates

With the economic globalization and the continuous improvement of people's living standard,the major problems that seriously affect environmental pollution and life and health have attracted more and more attention of researchers.As a new type of fluorescent nanomaterial,metal nanoclusters have many advantages including ultra-small size,stable optical properties and excellent biocompatibility,which make them have broad application prospects in biochemical sensing,cell imaging,environmental monitoring,medical diagnosis and treatment,etc.In this study,a variety of fluorescent metal nanoclusters were prepared by one-step synthesis using different cysteine proteases as biological templates,and explored their applications in biological monitoring and cell imaging.The main contents and results of this research are as follows:1.Preparation of fluorescent platinum nanoclusters with papain as a template and its application in lysozyme detection and bacterial imagingFluorescent platinum nanoclusters(Papain-Pt NCs)were synthesized using papain as a template,which had a small monodispersion size(?2.47 nm)and a strong green fluorescence emission at 490 nm(Ex=370 nm)in aqueous solution.For the detection of lysozyme,Papain-Pt NCs showed good selectivity and sensitivity.Furthermore,with the increasing concentration of lysozyme,the fluorescence intensity of Papain-Pt NCs gradually reduced and the detection limit was 16.94 nm.Meanwhile,Papain-Pt NCs realized to detect lysozyme content in human urine and serum,which become the sensor probe of lysozyme in the field of biological detection.In addition,Papain-Pt NCs could be used to image in gram-positive bacteria,which may provide a new strategy for biomarker.2.Fluorescent platinum nanoclusters coated with bifunctional bromelain for hydrogen peroxide detection and cell imagingBromelain coated platinum nanoclusters(Bromelain-Pt NCs)were prepared by a green,efficient one-pot method.The synthesized Bromelain-Pt NCs exhibit a clear green fluorescence(Em=480 nm)under the excitation wavelength of 370 nm.Furthermore,Bromelain-Pt NCs has good specificity and sensitivity to detect hydrogen peroxide,which may provide a new strategy for the detection of hydrogen peroxide.In addition,the Bromelain-Pt NCs with ultra-small size were proved to be suitable for the imaging of He La cell and MCF-7 cell,which are promising material candidates in the field of cell imaging.3.Preparation of nickel nanoclusters protected by ficin and its application in the detection of gentamicin sulfateNickel nanoclusters(Ficin-Ni NCs)with bright green fluorescence were synthesized by a simple one-step method using ficin as a template.The Ficin-Ni NCs with good optical stability had a maximum emission wavelength(Ex=480 nm)at 370 nm excitation wavelength.It was found that the fluorescence intensity of Ficin-Ni NCs at 480 nm was quenched rapidly in the presence of gentamicin sulfate,while there was no significant change in the existence of other antibiotics.Therefore,we constructed a fluorescent sensor based on Ficin-Ni NCs for the quantitative detection of gentamicin sulfate with a linear range of 5-60 ?g/m L and a detection limit of 0.43 ?g/m L.Ficin-Ni NCs were further applied to the detection of gentamicin sulfate in human serum.The results showed that the method had good recoveries,which could provide a new idea for the detection of gentamicin sulfate in complex biological environment.