No abstract

Infrared spectroscopic ellipsometry (IRSE) is a powerful tool for the characterization of various types of organic and inorganic films. In application to protein films, IRSE can be utilized to detect structural changes, orientation of specific group, etc. Because of sensitivity, enhanced IRSE will be very useful to study protein thin films. Here we show that fibroin films on Al mirror display surface‐enhanced infrared spectroscopic ellipsometry (SEIRSE). AFM data indicate that nanoislands on the Al mirror are responsible for the plasmon‐enhanced mechanism. SEIRSE for fibroin films shows non‐uniform enhancement across the spectrum. Possible mechanisms of such enhancement are provided. Evidently, as proposed previously, at least two mechanisms, the electromagnetic (EM) and chemical, are expected to contribute to the enhancement. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

The relationship between structure, dynamics, and function of biomolecules is a fundamental interest of biophysics. Protein dynamics drastically vary in temporal and spatial scales. The function of a particular protein determines the significance of a distinct type of dynamics. Here, we investigate the influence of hydration water on the dynamics of a protein called silk fibroin. Particular interest is to investigate the protein dynamics using thermal decay of the free radicals induced by ultraviolet irradiation. The full decay of the free radicals occurs at very wide temperature region (120 K–340 K). Three distinct regions with transition points of ∼135 K, 205 K, and 279 K are apparent in the thermal decay curves of hydrated fibroin samples. The first transition (∼135 K) that leads 2–6% increase of total spins was observed only in the decay curves of fibroin submerged in 40% and 50% glycerol. The second transition (∼205 K) was invariant for all samples, hydrated and dry fibroins. The third transition of 279 K common for all hydrated fibroin samples was shifted about 84 K to a higher temperature of 363 K in dry fibroin. The thermal transitions at 205 K and 279 K are weakly and strongly, respectively, coupled to water molecules. Nature of the free radicals participated in these transitions was identified. The significance of the findings for protein dynamics is discussed.

Surface enhanced Raman spectroscopy (SERS) owing to the greatly enhanced sensitivity is widely utilized to study biological molecules in various states. However, the enhancement in SERS is not uniform throughout the spectra. As a result, the strong enhancement of some transitions in SER overshadows weak Raman peaks that are very important to characterize the molecules. Here we show the SERS investigation for whole human blood on a nanostructured ZnO surface. The result indicates that despite the moderate enhancement (20–30 fold), all spectral components of the blood demonstrated in regular Raman are detected in SERS on ZnO. Moreover, SERS on ZnO identifies some components of the blood that are not easily accessible to regular Raman spectroscopy. Data indicate that SERS on ZnO is a valuable tool to investigate the whole blood for diagnosis of various human diseases.

Bioactive materials of natural origin have great demand in industry and medicine due to their versatility and useful properties. The main purpose of this work is to prepare biocomposites for the dual purpose of modified silk fibroin (Bombyx mori L.), which protects against the destructive effects of bioactive, antioxidant and ultraviolet rays. For this purpose, an aqueous extract of autumn leaves of the anthocyanin-rich smoke tree plant (Cotinus coggygria L.) was applied. 2% thiourea solution was used to increase the durability of the modified SF to external influences and for use in textiles. The intensity of free radicals in silk fibroin-anthocyanin (SFA) and silk fibroin-anthocyanin-thiourea (SFAT) biocomposites modified by the Electron Paramagnetic Resonance (EPR) method was studied. Maximum adsorption time was determined 20 minutes and the intensity of free radicals in SFA bio-composite was 80-85% and in SFAT biocomposite 50-55% in relation to silk fibroin untreated. For biomedical use of SFA, the radical scavenger activity kinetics were studied on a UV-2700 spectrophotometer and radical capture activity was calculated: RSA% (bioextract) = 73.52 ± 0.5, RSA% (SF) = 6.42 ± 0.4, RSA% (SFA) = 45.23 ± 0.8