RESUMO
Investigation into nanostructured organic films has served many purposes, including the design of functionalized surfaces that may be applied in biomedical devices and tissue engineering and for studying physiological processes depending on the interaction with cell membranes. Of particular relevance are Langmuir monolayers, Langmuir-Blodgett (LB) and layer-by-layer (LbL) films used to simulate biological interfaces. In this review, we shall focus on the use of vibrational spectroscopy methods to probe molecular-level interactions at biomimetic interfaces, with special emphasis on three surface-specific techniques, namely sum frequency generation (SFG), polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS) and surface-enhanced Raman scattering (SERS). The two types of systems selected for exemplifying the potential of the methods are the cell membrane models and the functionalized surfaces with biomolecules. Examples will be given on how SFG and PM-IRRAS can be combined to determine the effects from biomolecules on cell membrane models, which include determination of the orientation and preservation of secondary structure. Crucial information for the action of biomolecules on model membranes has also been obtained with PM-IRRAS, as is the case of chitosan removing proteins from the membrane. SERS will be shown as promising for enabling detection limits down to the single-molecule level. The strengths and limitations of these methods will also be discussed, in addition to the prospects for the near future.
Assuntos
Materiais Biomiméticos/química , Biofísica/métodos , Membrana Celular/química , Modelos Biológicos , Nanoestruturas/química , Animais , Materiais Biomiméticos/metabolismo , Fenômenos Biofísicos , Biofísica/tendências , Membrana Celular/metabolismo , Humanos , Membranas ArtificiaisRESUMO
Organisms living in deserts and anhydrobiotic species are useful models for unraveling mechanisms used to overcome water loss. In this context, late embryogenesis abundant (LEA) proteins and sugars have been extensively studied for protection against desiccation stress and desiccation tolerance. This article aims to reappraise the current understanding of these molecules by focusing on converging contributions from biochemistry, molecular biology, and the use of biophysical tools. Such tools have greatly advanced the field by uncovering intriguing aspects of protein 3-D structure, such as folding upon stress. We summarize the current research on cellular responses against water deficit at the molecular level, considering both plausible water loss-sensing mechanisms and genes governing signal transduction pathways. Finally, we propose models that could guide future experimentation, for example, by concentrating on the behavior of selected proteins in living cells.