Adsorption of Amino Acids onto Diamond for Biomedical Applications

📒 A range of DLC, Si-DLC, N-DLC and F-DLC films were prepared using ‎PECVD ‎with various film thicknesses (100-200) nm. The simplest amino acid ‎‎“Glycine” is used as a model biological compound to ‎investigate surface adsorption ‎phenomena. Following exposure to solutions ‎containing glycine, surface characteristic has been ‎investigated by various techniques. XPS analysis showed the appearance of a new ‎peak at 400 eV ‎‎(N1s) and a change in the intensity of the C1s and O1s peaks. Both ‎Raman and ‎FTIR spectra showed bands related to functional groups ‎of glycine. ‎AFM analysis showed a change in surface roughness of the films with ‎the ratio of ‎rms values increasing following exposure to glycine. Changes in the ‎surface energy of the films were observed following ‎exposure to glycine with an ‎increase in the surface tension. Based on the kinetic study, the adsorption ‎process ‎obeyed the pseudo first order rate of reaction, and both ∆G and ∆H results showed that the ‎adsorption is ‎spontaneous and exothermic. The ‎Freundlich-Langmuir isotherm ‎suggest that the attachment of glycine is non-‎uniform and multilayer. ‎