Synthesis Of Functionalized Gold Nanoclusters And Their Application In Fluorescent Array Sensing Analysis

Fluorescent gold nanoclusters with a diameter of less than 2 nm have attracted more and more attention due to their unique size and dependent physicochemical properties,including strong fluorescent signals and excellent biocompatibility.Therefore,fluorescent gold nanoclusters are widely used in the field of biomedical research,which involves biological imaging,biosensors,ion detection and protein quantitative analysis.In this thesis,gold nanoclusters were synthesized by a simple and easy preparation method.Based on the excellent chemical properties of gold nanoclusters,they were constructed into a new type of fluorescence sensor array,which was used to distinguish proteins and sulfur-containing substances,and further applied to the patient serum differentiation.This method is expected to become an auxiliary means for clinical diagnosis.The main research contents are summarized as follows:?1?In view of previous research on peptide gold nanoclusters,we independently designed a series of peptides by changing the amino acid sequence and synthesized a series of peptide gold nanoclusters using it as templates,from which the sequence as Cys-Met-Met-Met-Met-Met?CMMMMM?were selected as templates to synthesize CMMMMM-Au NCs with highly stable fluorescence and strong luminescence.Compared with CYYYYY-Au NCs synthesized by peptide Cys-Tys-Tys-Tys-Tys-Tys?CYYYYY?as template based on cysteine?C?and tyrosine?Y?,the fluorescence intensity is greatly improved,and the photobleaching resistance or stability of the CMMMMM-Au NCs increased by about 300%?after continuous ultraviolet irradiation for 60 minutes,the fluorescence of the CMMMMM-Au NCs remained more than 90%of their initial intensity,while the CYYYYY-Au NCs remained less than 30%?.Assaying arrays based on CMMMMM protected Au NCs with different positive or negative charges as sensing receptors were developed through regulating different pH values,which can not only effectively identify ten kinds of proteins and protein mixtures in complex biological samples,but also distinguish serums from breast cancer,rectal cancer,severe osteoarthritis and healthy people.The molecular docking simulation and isothermal titration calorimetry experiments show that proteins interacted with CMMMMM-Au NCs mainly through electrostatic interactions and partly hydrophobic interactions,which affected the binding energy and fluorescence life of CMMMMM-Au NCs,resulting in the unique fingerprint-like recognition patterns.This method shows a feasible prospect in the clinical auxiliary diagnosis of major diseases.?2?By changing the ligand molecule of synthesis template,we synthesized three different functionalized fluorescent gold nanoclusters,and constructed a sensor array based on Au NCs-Cu²⁺with the help of copper ion-mediated changes in the fluorescent signal to rapidly identify different types of sulfur-containing substances.Based on the fingerprint-like fluorescence response generated by competitive binding between Au NCs-Cu²⁺and different sulfur-containing species,it can not only distinguish ten different types of sulfur-containing substances,but also their binary or ternary randomly selected mixtures can be well discriminated.It's worth noting that it takes only 2 minutes to obtain the best response signals for sulfur-containing species discrimination.Most importantly,serums from cancer patients?such as liver cancer and breast cancer?and healthy people as well as sulfur-oxidizing bacteria?SOB?and sulfur-free bacteria can be both effectively and rapidly identified within 2 minutes.This method has potential application value in the rapid diagnosis of major diseases.