title: Characterization of the coupling of quantum dots and immunoglobulin antibodies.
abstract: Water-soluble quantum dots (QDs) were used to label goat anti-human immunoglobulin antibodies (Abs), and the labeling process was characterized by column purification. The QDs obtained in organic solvent were modified with mercaptoacetic acid (MAA) and became water-soluble. These water-soluble QDs were linked to the antibodies using the coupling reagents ethyl-3-(dimethyl aminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS). The linking process was shown to be effective by ultra-filter centrifugation and column purification. After comparing the quantities of Abs and water-soluble QDs involved in the linking reaction via column purification, it was found that a molar Abs:QD ratio of >1.2 resulted in most of the water-soluble QDs becoming covalently linked to the Abs. The circular dichroism (CD) spectra of Abs and QD-Ab conjugates were very similar to each other, indicating that the secondary structure of Abs remained largely intact after the conjugation. Finally, antigen (Ag)-antibody (Ab) recognition reactions perfomed on the surface of a glass slide showed that the conjugate retained the activity of Abs. This work lends support to the idea of linking biomolecules to QDs, and thus should aid the application of QDs to the life sciences.
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, Wuhan, HuBei, People's Republic of China.
authors.forename: Xiao-Feng
authors.initials: XF
authors.lastname: Hua
authors.forename: Tian-Cai
authors.initials: TC
authors.lastname: Liu
authors.forename: Yuan-Cheng
authors.initials: YC
authors.lastname: Cao
authors.forename: Bo
authors.initials: B
authors.lastname: Liu
authors.forename: Hai-Qiao
authors.initials: HQ
authors.lastname: Wang
authors.forename: Jian-Hao
authors.initials: JH
authors.lastname: Wang
authors.forename: Zhen-Li
authors.initials: ZL
authors.lastname: Huang
authors.forename: Yuan-Di
authors.initials: YD
authors.lastname: Zhao
mesh_terms: D006801:Humans; D007136:Immunoglobulins / Q000737:chemistry / Q000276:immunology*; D015394:Molecular Structure; D045663:Quantum Dots; D012995:Solubility; D013057:Spectrum Analysis; D014867:Water
chemical_list: D007136:Immunoglobulins; D014867:Water