Spectroscopic studies on molecular recognition capabilities of a nucleolipid bearing thymine headgroup to adenosine

The Langmuir- Blodgett (LB) films of octadecanoyl eater of 1-(2-carboxyethy l) thymine deposited from pure water and aqueous adenosine subphases were i nvestigated by ultraviolet-visible (UV-vis), Fourier transform infrared-att enuated total reflection (FTIR-ATR), and Fourier transform surface-enhanced Raman scattering (FT-SERS) spectroscopy. The obtained spectral results ind icate that the adenosine molecules in the subphase can be transferred onto solid substrates by LB techniques as a result of the formation of base pair s at the air/water interface. UV-vis spectra alternations indicated that, w ith increasing adenosine concentration in subphase, more adenosine molecule s were recognized by nucleolipid monolayer and were transferred onto the qu artz substrates. The closed-packing of the constituent molecules facilitate s the photodimerization of the thymine moieties in the headgroup under ultr aviolet irradiation. FTIR-ATR results suggest that the hydrocarbon chains o f nucleolipid in the LB films deposited from pure water and aqueous adenosi ne take on a close-packed all trans conformation. By analyzing the FT-SERS spectra results, it can be deduced that the orientation of nucleobase in th e headgroup is different before and after the recognition effect occurred. For LB film deposited from pure water, the nucleobases are lying flat on th e silver substrates; whereas for LB film deposited from aqueous adenosine, the base pairs take an end-on adsorption on silver substrate. (C) 2001 Else vier Science B.V. All rights reserved.