Fabrication DNA And Antibody Modified Bioactive Nanoconjugate

The item of this paper was bio-molecule self-assembly, Cinchonine self-assembly on the surface of silicon, and dual bio-molecules self-assembly on gold nanoparticles. Detect the property of bio-nano probe by TEM, UV-Vis spectra and so on. Both the antibody and ss-DNA retained their bioactivity on the nanoparticle surface, which were confirmed by dot-immuno experiment and cross-linking experiments, respectivity. The main contents are outlined as follows:1. Self-assembly of cinchonine on silicon: Cinchonine was self-assembled onto a Si-H surface via a photochemistry method at room temperature. The self-assembled monolayers (SAMs) obtained were characterized by means of ellipsometry, XPS and wettability studies. Contact angle titration data revealed that the surface of cinchonine underwent a transition around pH 10. SAMs were found to be less hydrophilic to an acidic solution than to a basic solution.2. Preparation of gold nanoparticle bio-probe: Antibody (IgG) and single strand DNA (ssDNA) were attached onto 10nm gold nanoparticle at optimal pH and antibody concentration. The antibody is attached through electrostatic interaction while the ssDNA were attached via S-Au bond. After IgG and DNA connected, the UV-Vis spectra should only a slight shift in the surface plasmon band. The IgG adsorption significantly improved the stability of the nano-bioprobe in aqueous solution, which is beneficial for attaching DNA.3. Reactivities and stabilities of the immobilized IgG and DNA: The olignucleotide (ss-DNA) labeled by SH- and fluorescence moieties were replaced by DTT, then the quantity of DNA on gold nanoparticles was determined by fluorescence spectroscopy. It was found that on each IgG labeled 10 nm gold nanoparticle there were 50±15(DNA/gold nanoparticles) . This value is smaller than that on only DNA modified gold nanoparticles. At the same times, the kinetics of DTT replacement of DNA were studied by UV-Vis spectroscopy. The functionnalized gold nanoparticles were tested by a dot immuno assay on an antigen containing substrate, which showed that the adsorbed IgGs remain bioactive. To detect the activity of ss-DNA, a specially designed linker oligonucleotide was employed, which contains two identical parts of the sequences that are complementary to the oligonucleotide on the gold nanoparticles. The aggregation of gold nanoparticles illustrates that the oligonucleotide bound onto the gold nanoparticle surface is able to hybridize with complementary oligonucleotide.