New trends in biomedical applications of the hybrid polymeric hydrogels, obtained by combining natural polymers with synthetic ones, have been reviewed. Homopolysaccharides, heteropolysaccharides, as well as polypeptides, proteins and nucleic acids, are presented from the point of view of their ability to form hydrogels with synthetic polymers, the preparation procedures for polymeric organic hybrid hydrogels, general physico-chemical properties and main biomedical applications (i.e., tissue engineering, wound dressing, drug delivery, etc.).
Food packaging is designed to protect foods, to provide required information about the food, and to make food handling convenient for distribution to consumers. Packaging has a crucial role in the process of food quality, safety, and shelf-life extension. Possible interactions between food and packaging are important in what is concerning food quality and safety. This review tries to offer a picture of the most important types of active packaging emphasizing the controlled/target release antimicrobial and/or antioxidant packaging including system design, different methods of polymer matrix modification, and processing. The testing methods for the appreciation of the performance of active food packaging, as well as mechanisms and kinetics implied in active compounds release, are summarized. During the last years, many fast advancements in packaging technology appeared, including intelligent or smart packaging (IOSP), (i.e., time–temperature indicators (TTIs), gas indicators, radiofrequency identification (RFID), and others). Legislation is also discussed.
Polyvinylidene fluoride (PVDF) was modified by CO 2 , N 2 or N 2 /H 2 plasmas, which permitted the attachment of short carboxyl or amino groups. A variation of the discharge parameters was performed, for their optimization, as well as for minimizing degradation in favour of acidic, amphiphilic or basic functionalization, respectively. The optimum parameters of discharge for CO 2 , N 2 or N 2 /H 2 plasmas were P = 50 W, gas flow rate Q = 16 × 10 −8 m 3 s −1 , exposure time t = 30-60 s, d = 0.1 m, pressure 15 Pa. The new surfaces were characterized by wettability measurements, attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), x-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) methods. In a second step, the proteins (triglycine (TG) and protein A) were adsorbed or chemically grafted onto the carboxyl or amino functionalized surface, after EDC/NHS (1-ethyl-3-(-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide) activation of proteins. ATR-FTIR, XPS and AFM investigations confirmed the presence of protein on the surface. The XPS C1s core levels at 286.3 eV (C-N), 288 eV (amide bond) and 298 eV (carboxylic acid), together with variation of the O1s and N1s signals, illustrated the immobilization of proteins. It was established that TG was better attached on surfaces activated with N 2 /H 2 plasma, while protein A was more tightly anchored on CO 2 , N 2 plasma-activated surfaces. The former procedure allowed higher surface densities, while the latter permitted a better chemical control. The results proved that plasma-treated PVDF is a good substrate for protein coating, which can be further used for microorganisms' detection, as evidenced by the immunoassay test.
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