title: Preparation of silica encapsulated quantum dot encoded beads for multiplex assay and its properties.
abstract: Novel -COOH modified polystyrene beads were prepared by sulfonation grafting, and the surface area and pore volume are greatly improved in comparison with the swelling-treated beads. The optimization coating time is 4 h, and the corresponding -COOH content is approximately 2.1 mmol/g. The scanning electron microscope results show that the silica particles deposited on the beads and formed a silica shell that decreases the leakage of quantum dots (QDs) preferably and improves the bar code stability greatly. The anti-photobleaching of silica-coated beads was studied systemically, and the results show that the half-decay time (t1/2) of the coated beads increases to 537 s--seven times longer than that of the uncoated ones. Further DNA probe hybridization experiments indicated that the coding signal and target signal can be detected simultaneously and that the assays based on these probe-conjugated silica/QD/polystyrene beads have good specificity and sensitivity that can detect a concentration as low as 0.01 microg/ml target DNA in denatured calf thymus DNA solution, indicating that it is feasible to use this kind of bead for multiplex analysis.
authors.affiliation: Key Laboratory of Biomedical Photonics of Ministry of Education-Hubei Bioinformatics and Molecular Imaging Key Laboratory, College of Life Science and Technology, Huazhong University of Science and Technology, Hubei, People's Republic of China.
authors.forename: Yuan-Cheng
authors.initials: YC
authors.lastname: Cao
authors.forename: Zhen-Li
authors.initials: ZL
authors.lastname: Huang
authors.forename: Tian-Cai
authors.initials: TC
authors.lastname: Liu
authors.forename: Hai-Qiao
authors.initials: HQ
authors.lastname: Wang
authors.forename: Xiao-Xia
authors.initials: XX
authors.lastname: Zhu
authors.forename: Zhan
authors.initials: Z
authors.lastname: Wang
authors.forename: Yuan-Di
authors.initials: YD
authors.lastname: Zhao
authors.forename: Man-Xi
authors.initials: MX
authors.lastname: Liu
authors.forename: Qing-Ming
authors.initials: QM
authors.lastname: Luo
mesh_terms: D004247:DNA / Q000032:analysis; D015342:DNA Probes; D008855:Microscopy, Electron, Scanning; D008863:Microspheres; D036103:Nanotechnology; D009693:Nucleic Acid Hybridization; D045663:Quantum Dots; D012680:Sensitivity and Specificity; D012822:Silicon Dioxide / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D013053:Spectrophotometry; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D015342:DNA Probes; D012822:Silicon Dioxide; D004247:DNA