Sensitive detection of Epstein-Barr virus-derived latent membrane protein 1 based on CdTe quantum dots-capped silica nanoparticle labels

Background: The detection of Epstein-Barr virus-derived latent membrane protein 1 (LMP-1) is essential for understanding its contribution to the development of malignancy in epithelial cells and the early screening of nasopharyngeal carcinoma tumors. It is important to explore novel means for enhancing detection sensitivity of LMP-1. Methods: The current strategy for enhancing sensitivity is based on signal amplification of LMP-1/cadmium telluride (CdTe) quantum dots (QDs) functionalized silica nanosphere labels (Si/QD/Ab2). Si/QD/Ab2 was fabricated by covalently binding LMP-1 antibody (denoted Ab2) to CdTe QDs, which have been previously coated onto the surface of silica nanoparticles with EDC Chemistry. The as-prepared Si/QD/Ab2 label can be brought to a modified gold slice by a "sandwiched" immunoreaction, which was confirmed by SEM images and detected by square wave voltammetry (SWV). Results: The amount of captured Si/QD/Ab2 by sandwiched immunoreaction was related to the concentration of LMP-1 in the incubation solution. The calibration range for LMP-1 detection was found to be 0.001 to 10 ng/ml with a correlation coefficient of 0.9897 and the lowest detectable concentration of 0.001 ng/ml. Compared with traditional sandwich immunoassay, the detection sensitivity of presented approach was enhanced largely due to the large surface area of silica nanoparticle carriers, which increased in CdTe QDs loading per sandwiched immunoreaction. Conclusion: The ease of functionalization, good monodispersed sizes and uniformity of the silica nanoparticles allows the QDs coated silica nanospheres to be highly suited for immunological labeling of trace protein analysis. The proposed method is simple, selective, reproducible, and can be extended to study protein-protein. peptide-protein, and DNA-protein interaction. (C) 2010 Elsevier B.V. All rights reserved.