Near-surface oxidized sulfur modifications and self-assembly of thiol-modified aptamer on Au thin film substrates influenced by piranha treatment.

Self-assembly of thiol-modified oligonucleotides on Au films has great importance for biosensor applications. Prior to the self-assembly, a piranha treatment (PT) is commonly used to clean the Au surface. Here we report that near-surface oxidized sulfur modifications on Au thin films by PT for longer than 60 s have serious effects on the self-assembled monolayer (SAM) formation of thiol-modified single-stranded thrombin binding aptamer (s-TBA), and a PT time of 10-30 s is optimal for s-TBA SAM formation. These results have important implication to SAM formation of biomolecules, especially for the thiol-modified ones where a careful consideration of this key step could significantly enhance the SAM formation and biosensor performance.

The effect of ultra-nanocrystalline diamond films on the proliferation and differentiation of neural stem cells.

The interaction of ultra-nanocrystalline diamond (UNCD) with neural stem cells (NSCs) has been studied along with its surface modification in order to improve its function as a biomaterial. Hydrogen- and oxygen-terminated UNCD films were compared with standard grade polystyrene in terms of their impact on the growth, expansion and differentiation of NSCs. When NSCs were cultured on these substrates in low serum and without any differentiating factors, hydrogen-terminated UNCD films spontaneously induced cell proliferation and neuronal differentiation. Oxygen-terminated UNCD films were also shown to further improve neural differentiation, with a preference to differentiate into oligodendrocytes. Hence, controlling the surface properties of UNCD could manipulate the differentiation of NSCs for different biomedical applications. These observations raise the potential for the use of UNCD as a biomaterial for central nervous system transplantation and tissue engineering.