RESUMO
The plasma-enhanced chemical vapor deposition (PECVD) technique has been utilized for the facile surface deposition of hydrogenated diamond-like carbon (HDLC) thin-films onto Si(100) substrates. The as-deposited film surface is homogenous, free of pinholes, and adheres to the substrate. Annealing of the synthesized HDLC surface in a vacuum was performed in the temperature range of 200 to 1000 °C. A host of instrumental techniques, viz. FTIR spectroscopy, AFM, STM, and EC-AFM, were successfully employed to detect the morphological transformation in the HDLC films upon annealing. EC-AFM studies show irreversible biased behavior after undergoing a surface redox couple reaction and morphological change. Raman spectroscopy was carried out along with STM and EC-AFM to determine the functional nature and conductivity of the annealed surface.
RESUMO
Hydrogenated diamond-like carbon (HDLC) has an atomically smooth surface that can be deposited on high-surface area substrata and functionalized with reactive chemical groups, providing an ideal substrate for protein immobilization. A synthetic sequence is described involving deposition and hydrogenation of DLC followed by chemical functionalization. These functional groups are reacted with amines on proteins causing covalent immobilization on contact. Raman measurements confirm the presence of these surface functional groups, and Fourier transform infrared spectroscopy (FTIR) confirms covalent protein immobilization. Atomic force microscopy (AFM) of immobilized proteins is reproducible because proteins do not move as a result of interactions with the AFM probe-tip, thus providing an advantage over mica substrata typically used in AFM studies of protein. HDLC offers many of the same technical advantages as oxidized graphene but also allows for coating large surface areas of biomaterials relevant to the fabrication of medical/biosensor devices.
