Investigation Of Detection Method For Lysozyme And Pathogenic Bacteria Based On Functionalized Gold Nanoparticles

Lysozyme is a kind of protein that can mark the functional changes or lesions of human organs,tissues and cells.It can be used as a reliable biochemical indicator for different disease such as leukemia.Meanwhile,human is also facing damage and invasion of pathogens,such as Staphylococcus aureus?S.aureus?.Therefore,it is of great significance to detect lysozyme and pathogenic bacteria for the prevention and diagnosis of human diseases.However,the current strategies for their detection show some shortcomings.For example,microbiological method is time-consuming,laborious and the repeatability is poor.Instrument analysis requires expensive instruments and preprocessing of samples.Immunoassay requires expensive antibodies in different batches.The method based on nanoprobe is limited due to the complex preparation of nanoprobe.Therefore,it is urgent to develop a new method which is simple,fast,specific,sensitive,accurate and efficient for detection of lysozyme and pathogens.In this work,firstly,a new method for detecting lysozyme was developed by using functional gold nanoparticles?AuNPs?based on the plasma resonance light scattering?PRLS?signal.Secondly,we employed the antibiotics and aptamer specific to bacteria to construct a nanomaterials surface energy transfer?NSET?sensor for detection of SA.The main contents are as follows:Part I:In this part,a simple,specific and sensitive method for detection of lysozyme is established based on the change of PRLS signal of peptidoglycan?PGN?stabilized-gold nanoparticles?PGN-AuNPs?.PGN-AuNPs with a uniform particle size,good stability and a specific biological function were prepared directly by using the recognition molecule of PGN as a template within 5 min.Based on the specific hydrolysis of PGN by lysozyme,within 1.5 h,the PRLS signals(?I_PRLS,at 560 nm)of PGN-AuNPs increased significantly due to the aggregation of AuNPs,and enhanced linearly with increasing concentration of lysozyme in the range of 5-1600 nmol/L with detection limit down to 2.32 nM(?I_PRLS=7.5978+0.5812 c,r=0.9974).When the method is used to detect lysozyme in human serum samples,the recovery efficiency is106.76-119.32%with the relative standard deviation?RSD?in the range of 0.14-3.11%,showing good feasibility.The method for detecting lysozyme based on PGN-AuNPs nanoprobe is simple,rapid,specific and sensitive,which is expected to provide a feasible new method for the clinical diagnosis of lysozyme-related diseases.Part II:In this part,we established a sensitive,specific,and quick method for detection of pathogens based on NSET sensor which was constructed using antibiotics and aptamer as recognition molecules simultaneously to pathogens.Pathogenic bacteria of SA were used as the research model to be detected.Aptamer modified quantum dots?aptamer-QDs?and Teico-functional gold nanoparticles?Teico-AuNPs?were employed as the energy donor and receptor,respectively to construct NSETsensor.Based on the above-mentioned NSET sensor,S.aureus were detected simple and rapidly by one step within 1 h.The NSETsignal shows a linear variation with a detection range of 10-5×10⁸cfu/mL and detection limit of 2 cfu/mL.(?F/F₀=0.1058log₁₀N-0.1664,R=0.9960,at525 nm).When the strategy further applied to detect S.aureus in real samples?e.g.,milk,orange juice and human serum?,it showed recovery efficiency from 84.5%to 110%,with RSD in the range of 0.01-0.44%.Ths work established a simple,convenient,specific,sensitive and universal method for detection of pathogenic bacteria,which is of potential significance for the monitoring of food safety and the diagnosis of infectious diseases.