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In this study, nanofiber surfaces were produced from a mixture of polyvinyl alcohol and silk sericin protein (PVA:SS) containing gelatin-coated silver nanoparticles (G-AgNPs) by electrospinning. For preparation of G-AgNPs, gelatin solution (1%, w/v) was mixed with 5 mM of AgNO3 solution and the mixture was heated and stirred for 2 h. AgNPs production has been observed with the brown color change that occurred in the solution. The absorbance of G-AgNPs was measured with a UV–Vis spectroscopy in the 300–700 nm range, and it was proved that AgNPs were formed with the surface plasmon resonance peak observed at 420 nm. Field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray analysis (EDS) analyses revealed that G-AgNPs were in spherical form and contained C, H, N, Ag elements in their structures, respectively. Antibacterial activity of the synthesized of G-AgNPs was shown with agar well diffusion test against to Escherichia coli and Staphylococcus aureus bacteria. In the second stage of the study, PVA:SS solutions were turned into nanofibers by electrospinning at certain conditions. G-AgNPs solutions were added in 3 different ratios of 10, 20 and 30% by volume to PVA:SS solutions, and these mixtures were turned into nanofibers with the same conditions. It has been shown by Fourier transform infrared spectroscopy (FTIR) analyses that the nanofiber surfaces obtained were composed of PVA:SS blend. The morphologies of nanofiber surfaces were investigated by FESEM analysis, and compared to PVA nanofibers collected alone, the fiber diameters of the groups containing PVA, sericin and G-AgNPs were found to be much lower. The presence of silver in nanofibers containing G-AgNPs was proven by EDS and X-ray fluorescence analyses. The thermal properties of nanofiber surfaces were investigated by thermogravimetric analysis, and it was observed that the thermal stability of nanofiber surfaces increased with the addition of sericin and G-AgNPs to PVA. Then, liquid medium tests were performed for finding the antibacterial activity of nanofiber surfaces containing various proportions of G-AgNPs on E. coli and S. aureus bacteria, and it was observed that nanofiber surfaces containing certain amounts of G-AgNPs inhibited the growth of both bacteria. It is thought that the functional and antibacterial surfaces obtained in the study will have the capacity to be used in many different areas such as wound dressing material. [ABSTRACT FROM AUTHOR]

In this work, a kind of amine-type PET fibers was synthesized by reacting hexamethylenediamine (HMDA) with methacrylic acid-g-poly(ethylene terephthalate) (PET-g-MAA) fibers for the adsorption of silk sericin-capped silver nanoparticles (S-AgNPs) to produce antimicrobial fibers. Firstly, PET fibers were grafted MAA by using free radical polymerization technique and HMDA was covalently connected to the grafted PET fibers. Then, for S-AgNPs synthesis, 10 mL of AgNO3 solution (1 mM, 5 mM and 10 mM) was mixed with 10 mL of 1% sericin solution at pH 11. The obtained solution was stirred at room temperature for 24 h. The color change from transparent to yellow–brown indicated the formation of S-AgNPs. AgNPs formation was also determined by measuring the absorbance spectra of S-AgNPs between 300 and 600 nm using UV–Vis spectrophotometer. To determine the antimicrobial properties of S-AgNPs, agar-well diffusion tests were performed. 5 mM and 10 mM S-AgNPs groups showed antimicrobial activity on Escherichia coli and Staphylococcus aureus. After characterization of the synthesized S-AgNPs with UV–Vis spectrophotometer, Zetasizer, FTIR and TEM, the modified PET fibers were coated with S-AgNPs (5 mM and 10 mM). The S-AgNPs coated PET fibers were characterized by FTIR, SEM and X-ray fluorescence spectroscopy. The antimicrobial activities of the obtained PET fibers were investigated on S. aureus and E. coli bacteria by using disk diffusion test. It was found that the S-AgNPs coated modified PET fibers exhibited antimicrobial activities toward both gram-positive and gram-negative bacteria. The resulting polymeric PET fibers containing nano-silver can be used as an antimicrobial surface for many applications such as wound dressing. [ABSTRACT FROM AUTHOR]

A composite superabsorbent silk sericin-g-poly(acrylic acid/attapulgite) was synthesized by the aqueous solution copolymerization method with potassium persulfate-sodium sulfite as the redox initiation system and N, N′-methylenebisacrylamide as the crosslinker. The structure of the attapulgite, silk sericin and the product was characterized via Fourier transform infrared absorption spectroscopy, scanning electron microscopy, and transmission electron microscopy. The influences of reaction variables on the swelling properties of the composite superabsorbent were studied and optimized. The addition of the natural silk sericin improved the swelling properties of the acrylic acid/attapulgite bipolymer. The maximum swelling capacities of the composite superabsorbent silk sericin-g-poly(acrylic acid/attapulgite) in pure water and in 0.9 % NaCl aqueous solution were 1,236 and 108 g/g, respectively. The optimal conditions were initiator, 0.6 %; acrylic acid, 2.5 M; crosslinker, 0.1 %; silk sericin, 10 %; attapulgite, 12 %; reaction temperature, 65 °C; and time, 4 h. [ABSTRACT FROM AUTHOR]

novel superabsorbent hydrogel has been synthesized with the crosslinking graft copolymerization of acrylic acid (AA) and acrylamide onto the chain of silk sericin. Potassium persulfate (KPS)-sodium sulfite (NaHSO) as redox initiation system and N, N′-methylenebisacrylamide (MBA) as crosslinker were used. The structure of the product characterized by Fourier transform infrared absorption spectroscopy and the surface morphology of the hydrogel were observed by scanning electron microscopy. The certain parameters of the graft copolymerization including the monomer, the initiator, the crosslinker concentration, neutralization degree of AA, reaction temperature, and time were systematically optimized to achieve a hydrogel with maximum swelling capacity (2150 g/g). The optimal conditions were initiator 8 mmol/L, MBA 2.5 mmol/L, neutralization degree of AA 75%, reaction temperature 55 °C, and time 6 h. The swelling ratio in salt solutions was also determined (in 0.9% NaCl aqueous solution: 98 g/g). In addition, the swelling capability of the hydrogel was measured in solutions with pH ranged from 1 to 13. The synthesized hydrogel exhibited a pH-dependent character. Water absorbency of the product in aqueous chloride salt solutions has the Na > Ca > Mg > Al order in the investigated concentration. [ABSTRACT FROM AUTHOR]