Optical Encoding Of Microbeads Based On The Silica Shell Encapsulated Quantum Dots Nanoparticles And Its Applications

In the recent years, there is an urgent requirement in the application of high-throughput analysis technology as the fast development in the biological science. Microbeads-based suspension microarrays are emerging as a new favorable analysis strategy, which have been paid wide attention in their potential applications in gene expression analysis studies, clinical diagnostics and rapid drug screening. The beads-based suspension microarray technology has been utilized as an alternative in the field of biological analysis.As a promising fluorescent probe, quantum dots (QDs) have been attempted to dope the microbeads in the suspension microarrays, which opened a new area in the development of multi-analysis technique based on optical encoding of microbeads.There are mainly two routes in the doping of QDs into microbeads for encoding: one way was that the QDs were directly absorbed into a porosity treated microbeads; as in the second method, the QDs were incorporated into microbeads during the synthesis of the microbeads. The coding signals of microbeads were resulted from two factors: the emission wavelengths of different QDs and the fluorescent intensity of different QDs. In order to obtain dependable microbeads coding, the research should be focused on the fluorescent stability of the optical encoding microbeads, which had a significant influence on the coding precision. However, the actual studies of multicolor encoding of beads with QDs still had many deficiencies and needed to be further improved. So it is still required to screen good methods to enhance the stability of the encoded beads.A novel method concerning the coding technology of polystyrene beads with Si encapsulated QDs (Si@QDs) nanoparticles was studied in this paper. In the reverse microemulsion system containing TEOS, water-soluble QDs (emission peak at 600 nm) were enveloped within the silica shell, forming Si@QDs nanoparticles. The Si@QDs nanoparticles were characterized by TEM, showing good uniform in size with the average diameter of about 167.0 nm. In comparison with the pure water-soluble QDs, the encapsulation of water-soluble QDs in silica shell led to an enhancement in anti-photobleaching by providing inert barriers for the QDs. Images presented by SEM and Confocal Laser Scanning Microscopy demonstrated that the Si@QDs nanoparticles were equably coated on the surface of carboxyl functionalized PS beads. Then, with the assistance of EDC/NHS, human IgG could be successfully crosslinked to the Si@QDs nanoparticles coated PS-COOH beads. Furthermore, the Si@QDs coated PS-COOH beads with human IgG were examined in the immunoassay experiments, and the results indicated that these beads could be applied in the specific recognition of goat-anti-human IgG in solution. This investigation was expected to provide a new route to the beads coding in the field of suspension microarray which was based on the using of QDs.