The development of new advanced biomaterials with interesting properties has attracted much more attention in the recent years. This paper presents a new bottom-up approach strategy to design noncovalent entities based on single walled carbon nanotubes (SWCNTs) and artificial lipid membranes (liposomes), with potential biomedical applications (drug delivery systems). Small unilamellar liposomes (SUVs) were prepared by thin film hydration method. Chlorophyll a (Chla) extracted from fresh spinach leaves, was incorporated in liposomes (Chla/lipid molar ratio =1/100) and used as a molecular sensor to monitor the changes occurred in the artificial lipid bilayers. SWCNTs were added to a suspension of Chla-SUVs and then subjected to ultrasound treatment. These nanobiomaterials were investigated by different spectral methods (DLS, UV-VIS absorption and emission). The originality of this work lies in the way of design, preparation and characterization of new nanobiomaterials by CNT biofunctionalization. The use of Chla is also another element of novelty. The spectral properties of Chla were exploited by introducing specific spectral parameters in order to monitor the changes at molecular level and the bionanomaterial time evolution. The biofunctionalization of CNTs with Chla-liposomes could be an effective method to increase CNT biocompatibility and to reduce their toxicity, getting bionanocomposites with biomedical applications.
Terahertz Time-Domain Spectroscopy (THz-TDS) is a new technique in studying the conformational state of molecules. Cell membranes are important structures in the interaction with extra cellular entities. Their principal building blocks are lipids, amphiphilic molecules that spontaneously self-assemble when in contact with water. In this work we report the use of THz-TDS in transmission mode to examine the behavior of supported phospholipid bilayers (SPBs) within the frequency range of 0.2 THz to 3 THz. SPBs were obtained by vesicle adsorption method involving the spread of a suspension (50-100 μl) of small unilamellar vesicles (SUVs) or multilamellar vesicles (MLVs) dissolved in PBS (phosphate buffer solution) on a support of silicon wafers. Both SUVs and MLVs were obtained from dipalmitoyl phosphatidylcholine (DPPC) and lecithin by using the thin-film hydration method. Broadband THz pulses are generated and detected using photoconductive antennas optically excited by a femtosecond laser pulse emitted from a self-mode locked fiber laser at a wavelength of 780 nm with a pulse widths of 150 fs. THz-TDS was proven to be a useful method in studying SPBs and their hydration states. The absorption coefficient and refractive index of the samples were calculated from THz measurements data. The THz absorption spectra for different lipids in SPBs indicate specific absorption frequency lines. A difference in the magnitude of the refractive index was also observed due to the different structure of supported lipid bilayers. The THz spectrum of DPPC was obtained by using theoretical simulations and then the experimental and theoretical THz spectra were compared.