Synthesis and Surface Modification of Poly (dimethylsiloxane) - Gold Nanocomposite Films for Biosensing Applications

Gold - poly(dimethylsiloxane) (Au - PDMS) nanocomposite freestanding films were prepared and used to study the binding of Human Serum Albumin (HSA) to polyclonal anti-HSA. A new method of synthesis was developed for sensing application when most of the gold nanoparticles have to be localized in the surface layer. The localized surface plasmon resonance band in gold nanoparticles is used to monitor the binding reaction. SEM and AFM images as well as the UV- Visible spectrum have shown that incubating the PDMS film in a diluted solution of chloroauric acid for 18 hours results in a good dispersion of gold nanoparticles on the polymer surface, without aggregation. The kinetics of the formation of Au-PDMS is studied by UV-Visible spectroscopy. Biosensing experiments carried out with the Au-PDMS composite showed a good sensitivity allowing the detection of 2.5 mg of antigen. Compared to the previous methods of fabrication, the present technique has the advantage of simplicity; the structures can be prepared under mild conditions and without using an external capping agent. The method is suitable for microfluidic sensing applications for a variety of biomolecules.