NTR AND VISIBLE INVESTIGATION OF SOME POTENTIAL SERS-ACTIVE SUBSTRATES FOR STUDYING ANTITUMOR AGENT ALL-TRANS-RETINOIC ACID

Red and near-infrared excited Fourier transform surface-enhanced Raman spectra of an anticancer agent, all-trans retinoic acid (ATRA), adsor bed on gold island films are reported. Best results have been obtained with plates 80 Angstrom and 40 Angstrom thick respectively in the red and near-infrared and at concentrations of 10(-5) and 5 x 10(-6) M wi th a spinning system. The use of near-infrared laser excitation with l ow photon energy, allows us to overcome the problems of isomerisation when the sample is exposed for a long time to the laser radiation. Com parison between the Raman and SERS spectra in the visible shows that t he adsorption on the surface does not perturb the structure of ATRA an d confirms the long range enhancement of the island films with this ty pe of molecule. Spectral data show that while gold island films and co lloids are appropriate substrates for use with red excitation, silver and gold colloids as well as gold island films exhibit satisfactory en hancement levels in the near-infrared. This study will in the future a llow us to choose the appropriate system that will serve to investigat e the interaction of ATRA with its target in vitro and the effect of t his differentiating agent in human leukaemia cell lines such as K562 a nd HL60.