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In this work, we describe the application of FTIR spectroscopy to study lipids and proteins, in cellular systems during heating and cooling. Various spectral analysis methods are described to simultaneously study membrane phase behavior and heat-induced protein denaturation in cells. Membrane phase behavior was studied by following the temperature dependence of the CH2stretching vibration bands. Protein denaturation was studied using the amide-I and -III bands. Both amide-I and amide-III band analysis show that heat-induced denaturation of proteins within the cells is typically associated with an increase in extendedβ-sheet structures and a concomitant decrease in α-helical structures.

Objective: Blend electrospinning has been acknowledged as a cost-effective technique for the production of fibrous scaffolds, suitable for various biomedical applications. Coaxial electrospinning is a method variant that results in core-shell structures with advantages, such as delayed diffusion and protection of sensitive biomolecules. The aim of this work was to evaluate how different process and solution parameters affect the structural, mechanical and physical properties of the fibers, created by polycaprolactone (PCL). In addition, acetylsalicylic acid (ASA) that was used as a model anti-inflammatory and anti-thrombotic agent, was loaded within the fiber meshes in order to compare release kinetics between fibers produced by conventional blend and coaxial electrospinning. Methods: Scanning electron microscopy (SEM) was used to investigate the structural and morphological characteristics of the fibers. The fibers' hydrophilicity was investigated using contact angle measurements while the electrical conductivity of the polymeric solutions and the thermal properties of the fibers were also evaluated. Differential scanning calorimetry (DSC) was used to determine the fibers' melting point and mechanical tensile tests were performed in order to study the mechanical properties of the fibers. Moreover, UV-vis spectroscopy was used to determine the release kinetics of ASA. Results: The results indicated that increasing the concentration of PCL led to thicker and less aligned fibers. Furthermore, the physicochemical characterization did not reveal significant changes during the process. Coaxially electrospun fibers that were loaded with ASA exhibited a slower and sustained, biphasic release profile compared to blend electrospun fibers with 34% of ASA released during the first 8h and 97% in total after 3 months. Conclusion: Taken together, fibrous meshes created by coaxial electrospinning using PCL, can be tailor-made by a careful optimization of all the process and solution parameters, in order to fit the scope of specific applications in the fields of biomedical engineering and drug delivery.

Even though dried sperm is not viable, it can be used for fertilization as long as its chromatin remains intact. In this study, we investigated drying- and temperature-induced conformational changes of nucleic acids and stallion sperm chromatin. Sperm was diluted in preservation formulations with and without sugar/albumin and subjected to convective drying at elevated temperatures on glass substrates. Accumulation of reactive oxygen species was studied during storage at different temperatures, and the sperm chromatin structure assay was used to assess DNA damage. Fourier transform infrared spectroscopy was used to identify dehydration and storage induced conformational changes in isolated DNA and sperm chromatin. Furthermore, hydrogen bonding in the preservation solutions associated with storage stability were investigated. Reactive oxygen species and DNA damage in dried sperm samples were found to accumulate with increasing storage temperature and storage duration. Non-reducing disaccharides (i.e., trehalose, sucrose) and albumin counteracted oxidative stress and preserved sperm chromatin during dried storage, whereas glucose increased DNA damage during storage. When sperm was dried in the presence of trehalose and albumin, no spectral changes were detected during storage at refrigeration temperatures, whereas under accelerated aging conditions, i.e., storage at 37 °C, spectral changes were detected indicating alterations in sperm chromatin structure.

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