In this paper, the DNA-templated Ag/Pt bimetallic nanoclusters were successfully synthesized using an optimized synthetic scheme. The obtained DNA-Ag/Pt NCs have an ultrasmall particle size and excellent distribution....In this paper, the DNA-templated Ag/Pt bimetallic nanoclusters were successfully synthesized using an optimized synthetic scheme. The obtained DNA-Ag/Pt NCs have an ultrasmall particle size and excellent distribution. The DNA-Ag/Pt NCs show intrinsic peroxidase-mimicking activity and can effectively catalyze the H2O2-mediated oxidation of a substrate, 3,30,5,50-tetramethylbenzidine（TMB）, to produce a blue colored product. Based on this specific property, we employed the aptamer of VEGF to design a label-free electrochemical biosensor for VEGF detection. Under the optimized experimental conditions, a linear range from 6.0 pmol/L to 20 pmol/L was obtained with a detection limit of 4.6 pmol/L. The proposed biosensor demonstrated its high specificity for VEGF and could directly detect the VEGF concentration in human serum samples of breast cancer patients with satisfactory results. This novel electrochemical aptasensor was simple and convenient to use and was cost-effective and label-free in design, and would hold potential applications in medical diagnosis and treatment.展开更多
Detection of enzyme biomarkers originating from either bio-fluids or contaminating microorganisms is of utmost importance in clinical diagnostics and food safety. Herein, we present a simple, low-cost and easy-to-use ...Detection of enzyme biomarkers originating from either bio-fluids or contaminating microorganisms is of utmost importance in clinical diagnostics and food safety. Herein, we present a simple, low-cost and easy-to-use sensing approach based on the switchable peroxidase-mimicking activity of plasmonic gold nanoparticles (AuNPs) that can catalyse for the oxidation of 3,3’,5’5-tetramethylbenzidine (TMB) for the determination of protease enzyme. The AuNP surface is modified with casein, showing dual functionalities. The first function of the coating molecule is to suppress the intrinsic peroxidase-mimicking activity of AuNPs by up to 77.1%, due to surface shielding effects. Secondly, casein also functions as recognition sites for the enzyme biomarker. In the presence of protease, the enzyme binds to and catalyses the degradation of the coating layer on the AuNP surface, resulting in the recovery of peroxidase-mimicking activity. This is shown visually in the development of a blue colored product (oxidised TMB) or spectroscopically as an increase in absorbance at 370 and 650 nm. This mechanism allows for the detection of protease at 44 ng·mL^-1 in 90 min. The nanosensor circumvents issues associated with current methods of detection in terms of ease of use, compatibility with point-of-care testing, low-cost production and short analysis time. The sensing approach has also been applied for the detection of protease spiked in ultra-heat treated (UHT) milk and synthetic human urine samples at a limit of detection of 490 and 176 ng·mL^-1, respectively, showing great potential in clinical diagnostics, food safety and quality control.展开更多
基金support of the National Natural Science Foundation of China (Nos. 21375017, 21105012 and 21205015)the National Science Foundation for Distinguished Young Scholars of Fujian Province (No. 2013J06003)+3 种基金the Key Project of Fujian Science and Technology (No. 2013Y0045)the Program for New Century Excellent Talents of Colleges and Universities in Fujian Province (Nos. JA13130 and JA13088)the Program for Fujian University Outstanding Youth Scientific Research (Nos. JA11105 and JA10295)the Foundation of Fuzhou Science and Technology Bureau (No. 2013-S-122-4)
文摘In this paper, the DNA-templated Ag/Pt bimetallic nanoclusters were successfully synthesized using an optimized synthetic scheme. The obtained DNA-Ag/Pt NCs have an ultrasmall particle size and excellent distribution. The DNA-Ag/Pt NCs show intrinsic peroxidase-mimicking activity and can effectively catalyze the H2O2-mediated oxidation of a substrate, 3,30,5,50-tetramethylbenzidine（TMB）, to produce a blue colored product. Based on this specific property, we employed the aptamer of VEGF to design a label-free electrochemical biosensor for VEGF detection. Under the optimized experimental conditions, a linear range from 6.0 pmol/L to 20 pmol/L was obtained with a detection limit of 4.6 pmol/L. The proposed biosensor demonstrated its high specificity for VEGF and could directly detect the VEGF concentration in human serum samples of breast cancer patients with satisfactory results. This novel electrochemical aptasensor was simple and convenient to use and was cost-effective and label-free in design, and would hold potential applications in medical diagnosis and treatment.
文摘Detection of enzyme biomarkers originating from either bio-fluids or contaminating microorganisms is of utmost importance in clinical diagnostics and food safety. Herein, we present a simple, low-cost and easy-to-use sensing approach based on the switchable peroxidase-mimicking activity of plasmonic gold nanoparticles (AuNPs) that can catalyse for the oxidation of 3,3’,5’5-tetramethylbenzidine (TMB) for the determination of protease enzyme. The AuNP surface is modified with casein, showing dual functionalities. The first function of the coating molecule is to suppress the intrinsic peroxidase-mimicking activity of AuNPs by up to 77.1%, due to surface shielding effects. Secondly, casein also functions as recognition sites for the enzyme biomarker. In the presence of protease, the enzyme binds to and catalyses the degradation of the coating layer on the AuNP surface, resulting in the recovery of peroxidase-mimicking activity. This is shown visually in the development of a blue colored product (oxidised TMB) or spectroscopically as an increase in absorbance at 370 and 650 nm. This mechanism allows for the detection of protease at 44 ng·mL^-1 in 90 min. The nanosensor circumvents issues associated with current methods of detection in terms of ease of use, compatibility with point-of-care testing, low-cost production and short analysis time. The sensing approach has also been applied for the detection of protease spiked in ultra-heat treated (UHT) milk and synthetic human urine samples at a limit of detection of 490 and 176 ng·mL^-1, respectively, showing great potential in clinical diagnostics, food safety and quality control.
