Characterisation of protein adsorption on different liquid crystal phthalocyaninethin films

Bovine serum albumin (BSA) protein adsorption on thin spun films of different metal octakishexylthiophthalocyanine [(C₆S)₈PcM, M=Cu, Ni] derivatives is investigated by using three independent spectroscopic measurements namely Raman spectroscopy, ellipsometry and surface plasmon resonance imaging. Thermally induced molecular self-reorganisations in the phthalocyanine films are found to have produced the changes in the surface energy which, in turn, control protein adsorption. The amount of BSA adsorption on [(C₆S)₈PcNi] is more limited than that on [(C₆S)₈PcCu] and this observation is consistent with the results on the surface wettability obtained from the contact angle measurements. The shift from the plasmonic resonance wavelength because of the BSA adsorption was significantly larger for the heat-treated [(C₆S)₈PcCu] than as-deposited film. Similar measurements on the [(C₆S)₈PcNi] films showed a limited BSA adsorption. The results of surface plasmon resonance experiments are consistent with those obtained from Raman spectroscopic and ellipsometric techniques.