నానోమెడిసిన్ & నానోటెక్నాలజీ జర్నల్

నైరూప్య

An Organic Nanoparticle based High Signal Amplification Immunoassay with Improvement of Nonspecific Binding

Zhan Wang and Yuan-Cheng Cao

A high signal amplification immunoassay method based on Fluorescein Diacetate (FDA) organic nanoparticle was proposed here. FDA nanoparticles were prepared in a ball mill and centrifugation was applied to get the size-uniformed SDS stabilized particle (FDA@SDS). Further SEM images confirmed the particle size was well dispersed in solution and particle size analysis results showed that the particle size 90% was distributed in the range of 200 nm to 500 nm. Mass Spectrometry results showed that the antibody can directly attach to the FDA@SDS particles and standard sandwich immunoassay confirmed the bioactivity of the antibody on the FDA@SDS particle surface (FDA@SDS-IgG). And then Zeta potential test results showed that the blocking reagents BSA and Casein can successfully block the unsatisfied sites on the FDA@SDS-IgG surface, which resulted in the improvement of nonspecific binding and stabilization. Further experiments were carried out using the standard immunoassays which showed the analyte signal can be greatly amplified when Casein was used as block buffer in the immunoassays. The limitation of detection was lower than 10 pg/mL, which is 100 times lower than Cy3 or FITC directly labeled antibody. The improved procedure simplifies previously reported protocols and provides a simple high signal amplification immunoassay.