Enzyme-Functionalized Silica Nanoparticles as Sensitive Labels in Biosensing

• Published in: Analytical chemistry (Washington) Vol. 81; no. 4; pp. 1600 - 1607
• Main Authors: Wu, Yafeng, Chen, Chengliang, Liu, Songqin
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 15.02.2009
• Subjects: alpha-Fetoproteins - analysis; alpha-Fetoproteins - immunology; alpha-Fetoproteins - metabolism; Analytical chemistry; Animals; Antibodies, Immobilized - chemistry; Antibodies, Immobilized - immunology; Biocatalysis; Biological and medical sciences; Biomarkers - analysis; Biomarkers - blood; Biomarkers - metabolism; Biosensing Techniques - methods; Biosensors; Biotechnology; Cattle; Chemical and thermal methods; Chemistry; Electrocatalysis; Electrochemical methods; Electrochemistry; Enzymes; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Gold - chemistry; Horseradish Peroxidase - metabolism; Humans; Hydrogen Peroxide - chemistry; Hydrogen Peroxide - metabolism; Immunoassay; Luminescence; Luminol - chemistry; Methods. Procedures. Technologies; Miscellaneous; Nanoparticles - chemistry; Oxidation-Reduction; Phenothiazines - chemistry; Scanning electron microscopy; Sensitivity and Specificity; Silanes - chemistry; Silica; Silicon - chemistry; Silicon Dioxide - chemical synthesis; Silicon Dioxide - chemistry; Silicon Dioxide - metabolism; Staining and Labeling; Various methods and equipments; Scanning electron microscopy; Gold; Particle size; Microsphere; Antibody; Enzyme; Electrochemical method; Nanoparticle; Biological marker; Chemiluminescence; Chemical sensor; Silica; Immunosensor; Protein; Immunological method; Sensitivity; Peroxidases; Reproducibility; Biosensor; Peroxidase; Oxidoreductases; Surface area; Comparative study
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac802345z

A novel strategy for sensitive detection of biomarkers using horseradish peroxidase (HRP)-functionalized silica nanoparticles as the label is presented. The enzyme-functionalized silica nanoparticles were fabricated by coimmobilization of HRP and α-fetoprotein antibody (anti-AFP, the secondary antibody, Ab2), a model protein, onto the surface of SiO2 nanoparticles using γ-glycidoxypropyltrimethoxysilane (GPMS) as the linkage. Through “sandwiched” immunoreaction, the enzyme-functionalized silica nanoparticle labels were brought close to the surface of gold substrates, as confirmed by the scanning electron microscopy (SEM) images. Enhanced detection sensitivity was achieved where the large surface area of SiO2 nanoparticle carriers increased the amount of HRP bound per sandwiched immunoreaction. The electrochemical and chemiluminescence measurement showed 29.5- and 61-fold increases in detection signals, respectively, in comparison with the traditional sandwich immunoassay. The improved particle synthesis using a “seed-particle growth” route yielded particles of narrow size distribution, which allowed consistent loading of HRP and anti-AFP on each microsphere and ensured subsequent immunosensing possessed high sensitivity and reproducibility. This strategy was successfully demonstrated as a simple, cost-effective, specific, and potent method to detect AFP in practical samples.