| Applications of gold nanoparticles are attracting more and more interest in biomolecular detection due to their many advantages. Gold nanoparticles have been widely applied to nucleic acid detection, protein determination and immunoassay. Interaction between gold nanoparticles and mercapto group is use to modify the surface of gold nanoparticles. Mercapto biomolecules play an important role in life activity. It functions in the detoxification of hydrogen peroxide, other peroxides and free radicals. And the concentration level of these compounds in vivo related to some diseases. So, it is very important to develop method for determination of mercapto biomolecules in such diseases diagnoses.Resonance light scattering (RLS) not only has high sensitivity but also offers high selectivity in research of dye molecule assembly. There is large difference between RLS spectrum of dye molecule and gold nanoparticles.We demonstrated that light scattering spectrum of gold nanoparticles had resonance light scattering spectral characteristics. When gold nanoparticles self-assemble to form a network structure, resonance light scattering intensity of gold nanoparticles can be greatly enhanced and it is due to the increase of scatter's volume and surface plasmon coupling among gold nanoparticles. Form the essential resonance light scattering theory; we have discussed the principle of gold nanoparticle resonance light scattering and enhanced light scattering when gold nanoparticle aggregation occurred.Based on the work mentioned above and farther study of interaction between mercapto biomolecules (cysteine, glutathione) and gold nanoparticles, a rapid and sensitive method for cysteine and glutathione determination is established, respectively. Interaction mechanism between gold nanoparticles and cysteine is very similar to it between gold nanoparticles and glutathione. Through the covalent combination with the -SH group and the electrostatic binding with the -NH3+ group in molecules, gold nanoparticles can self-assemble to form a network structure, which results in greatly enhanced resonance light scattering. In this method, the linear range of determination of cysteine is from 0.01 to 0.25 μg mL-1 with the detection... |
