Effect of hydrolysis, phosphorylation and treatment with high hydrostatic pressure on thermal generation of stable and short-living radicals in maize starch was studied by X-ray diffraction (XRD), electron paramagnetic resonance (EPR) spectroscopy, differential scanning calorimetry and polarized light microscopy. Phosphorus was introduced into maize starch as monoand distarch phosphates. XRD indicated localization of phosphate groups in amorphous part of the granule whereas calorimetric data suggested some cross-linking of the distarch phosphates. Stable and short-living radicals with unpaired electron localized at carbon atom were generated in all investigated samples in the temperature range commonly used for processing food. The number of detected short-living radicals, stabilized by a spin trap, is of two orders of magnitude greater than that of the stable radical species. Hydrolysis and phosphorylation strongly increase the number of stable radicals while pretreatment of the starch with high hydrostatic pressure diminishes their amount. The EPR spectra of stable radicals consist of two components, single line and another one with hyperfine structure, indicating interaction of unpaired electron with neighboring hydrogen atom. The EPR spectra of the spin trap adducts with short-living radicals contain three components from species differing in their dynamic properties depending on localization in zones of various degree of crystallinity.
Nowadays, despite significant advances in the field of biomaterials for tissue engineering applications, novel bone substituents still need refinement so they can be successfully implemented into the medical treatment of bone fractures. Generally, a scaffold made of synthetic polymer blended with nanofillers was proven to be a very promising biomaterial for tissue engineering, however the choice of components for the said scaffold remains questionable. The objects of the presented study were novel composites consisting of poly(ε-caprolactone) (PCL) and two types of graphene materials: graphene oxide (GO) and partially reduced graphene oxide (rGO). The technique of choice, that was used to characterize the obtained composites, was Raman micro-spectroscopy. It revealed that the composite PCL/GO differs substantially from the PCL/rGO composite. The incorporation of the GO particles into the polymer influenced the structure organisation of the polymeric matrix more significantly than rGO. The crystallinity parameters confirmed that the level of crystallinity is generally higher in the PCL/GO membrane in comparison to PCL/rGO (and even in raw PCL) that leads to the conclusion that the GO acts as a nucleation agent enhancing the crystallization of PCL. Interestingly, the characteristics of the studied nanofillers, for example: the level of the organisation (D/G ratio) and the in-plane size of the nano-crystallites (La) almost do not differ. However, they have an ability to influence polymeric matrix differently.
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