Preparation of aminodextran-CdS nanoparticle complexes and biologically active antibody-aminodextran-CdS nanoparticle conjugates

Stable aqueous dispersions consisting of CdS nanoparticles having modal dia meters, ranging between 2 and 8 nm, were prepared with amino-derivatized po lysaccharides (aminodextrans, hence abbreviated as Amdex) as the stabilizin g agents. The size, stability, and luminescence intensity of such dispersio ns were shown to be dependent on the types of the cadmium salts and aminode xtrans used, as well as on the reactant concentrations. Specifically, it wa s demonstrated that the degree of substitution of amino groups in the amino dextran molecules greatly affected the properties of the dispersions; i.e., with higher degree of substitution, smaller CdS particles and higher lumin escence intensity were achieved. It was also shown that the Amdex-CdS nanop article complexes could be activated and conjugated with antibody by conven tional means. Molecular weight ranges of the Amdex and their complexes with CdS nanoparticles and the purity of antibody-Amdex-CdS nanoparticle conjug ates were determined by polyacrylamide gel electrophoresis combined with Co omassie blue staining of resultant gel bands. The purified conjugate of the aminodextran-CdS nanoparticle complex with anti-CD4 monoclonal antibody wa s mixed with a whole blood control, followed by indirect sheep antimouse an tibody-phycoerythrin (SAM-PE) labeling of washed cells incubated with T4-5X -Amdex-CdS. Red blood cells were then lysed and quenched, and the resulting mixture, which was run on a flow cytometer with 488.0 nm argon ion laser e xcitation, suggested that the T4 antibody from the conjugate was present sp ecifically on lymphocytes.