In this work, a non-covalent interaction of iron and metal-free meso-tetra (4-sulfonatophenyl) porphines (FeTPPS and TPPS, respectively) with high-quality single-layer graphene is studied by Raman spectroscopy. Such a kind of graphene functionalization is promising for a development of novel optoelectronic devices and sensors. Our results show that the central metal atom of porphyrin macrocycle, iron particularly, plays an important role in the integrity of FeTPPS on graphene surface; however, the predicted Raman enhancement is not significant. The interaction of metal-free TPPS with graphene leads to the deprotonation of TPPS molecules and higher Raman enhancement values. Moreover, initially deprotonated TPPS solutions after the adsorption onto the graphene surface demonstrate the appearance of new Raman bands and significantly enhanced Raman signals. We propose that a strong interaction between deprotonated TPPS and graphene is realized through pyrrole and desulfonated phenyl rings of closely located planar TPPS molecules on the graphene surface. The results show that both the protonation of porphyrin macrocycle and the existence of central metal atom are crucial for a formation of nanocomposites with defined electronic properties. Figure 2. Normalized Raman spectra of TPPS (a) and FeTPPS (b) films formed onto the glass substrates and the difference spectra (c) towards the ones of crystalline powders. The pH of initial solutions is displayed in the legend. The spectra are taken at an excitation wavelength of 532 nm, a laser power on the sample of 100 μW and an acquisition time of 120 s. The proposed molecular configurations of TPPS and FeTPPS at different pH are drawn using Jmol software and shown at the bottom of figure. (This figure is available in colour online at wileyonlinelibrary.com/journal/jrs) D. Naumenko et al. wileyonlinelibrary.com/journal/jrs
Nanoparticles (NP) are broadly exploited in biomedical sciences in order to develop various methods of targeted drug delivery, novel biosensors and new therapeutic pathways. However, relatively little is known in the negotiation of NPs with complex biological environments. NP interaction with cell membranes can damage the cell membrane and cause toxicity; therefore, examining interactions between NPs and cell membranes is crucial to understanding NP toxicity mechanisms and the development of safe and non-toxic NP-based commercial and therapeutic applications. To gain a physical understanding of NP-membrane interactions, we used a simplified system built of well-defined synthetic lipid bilayers and NP. The interaction of nanoparticles (NPs) with supported lipid bilayers (SLB) can lead to structural modification of the SLB and affect the structure and dynamic of lipids. In this work TiO 2 and ZnO nanoparticles were chosen because of wide applications and usage in industry of papers, inks, medicines, food products, cosmetics, toothpastes and skin care products and among others. Therefore, a better understanding of the interactions between NP and lipid membrane may help to better clarify the potential risk of NPs. The interaction between ZnO and TiO 2 NPs and lipid membranes was studied by using scanning supercritical angle fluorescence microscopy. The biological response to elucidated changes in lipid membrane structure/characteristics under ZnO or TiO 2 NP influence was tested by fluorescence correlation spectroscopy. It was found the significant reduction of lipids diffusion mobility, which can be explained as a result of lipid-ZnO aggregates binding, depending on ZnO concentration. The TiO 2 has a little effect on lipids diffusion mobility.
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