Films of Poly(Hydroxybutyrate) (PHB) and Copper with Antibacterial Activity.

Poly(3-hydroxybutyrate), PHB, is a hydrophobic biopolymer with good mechanical and barrier properties. However, neat PHB is a semicrystalline polymer with a relative high degree of crystallinity and poor film properties. In this work, this biopolymer was plasticized with glycerol tributyrate and functionalized with copper (II) sulfate, allowing us to obtain biodegradable antimicrobial flexible films. Films with the minimum inhibitory concentration (MIC) of copper (II) sulfate presented a higher roughness than neat PHB films. The presence of plasticizer significantly improved the copper sulfate diffusion process, which was evidenced by a greater inhibition halo for plasticized materials compared to unplasticized ones, at the same salt concentration. Plasticized PHB with 2.5% copper (II) sulfate inhibited both Gram-positive (Staphylococcus aureus) and Gram-negative (Pseudomona aeruginosa) bacteria, as determined by the bacterial inhibition halo. In addition, neat PHB films and PHB containing copper (II) sulfate did not show in vitro cytotoxicity in the L-929 cell line. Thus, plasticized PHB functionalized with copper (II) sulfate can be used as biodegradable antimicrobial flexible films for different applications.

Recycling of hyoscyamine 6ß-hydroxylase for the in vitro production of anisodamine and scopolamine.

The tropane alkaloids hyoscyamine, anisodamine, and scopolamine are extensively used medicines. In particular, scopolamine has the greatest value in the market. Hence, strategies to enhance its production have been explored as an alternative to traditional field-plant cultivation. In this work, we developed biocatalytic strategies for the transformation of hyoscyamine into its products utilizing a recombinant Hyoscyamine 6ß-hydroxylase (H6H) fusion protein to the chitin-binding domain of the chitinase A1 from Bacillus subtilis (ChBD-H6H). Catalysis was carried out in batch, and recycling of H6H constructions was performed via affinity-immobilization, glutaraldehyde crosslinking, and adsorption-desorption of the enzyme to different chitin matrices. ChBD-H6H utilized as free enzyme achieved complete conversion of hyoscyamine in 3- and 22-h bioprocesses. Chitin particles demonstrated to be the most convenient support for ChBD-H6H immobilization and recycling. Affinity-immobilized ChBD-H6H operated in a three-cycle bioprocess (3 h/cycle, 30 °C) yielded in the first and third reaction cycle 49.8% and 22.2% of anisodamine and 0.7% and 0.3% of scopolamine, respectively. However, glutaraldehyde crosslinking decreased enzymatic activity in a broad range of concentrations. Instead, the adsorption-desorption approach equaled the maximal conversion of the free enzyme in the first cycle and retained higher enzymatic activity than the carrier-bound strategy along the consecutive cycles. The adsorption-desorption strategy permitted the reutilization of the enzyme in a simple and economical manner while exploiting the maximal conversion activity displayed by the free enzyme. This approach is valid since other enzymes present in the E. coli lysate do not interfere with the reaction. KEY POINTS: • A biocatalytic system for anisodamine and scopolamine production was developed. • Affinity-immobilized ChBD-H6H in ChP retained catalytic activity. • Enzyme-recycling by adsorption-desorption strategies improves product yields.

Smart release of antimicrobial ZnO nanoplates from a pH-responsive keratin hydrogel.

A smart antibacterial biomaterial based on a keratin hydrogel with pH-dependent behavior and Zinc Oxide nanoplates as biocide agent has been developed. The pH of a chronic wound is basic due to bacterial metabolism. Originally shrank at acid pH, keratin hydrogels swell upon contact with a bacterial contaminated media leading to the release of the nanoparticles. The material has been thoroughly characterized by infrared spectroscopy, Raman, scanning electron microscope, swelling behavior, Differential scanning calorimetry, Small-angle X-ray scattering, rheology, antimicrobial activity and cytotoxicity. The results show that 5% of Zinc Oxide nanoparticles concentration is the optimum for wound dressing applications.

Changes in iron transporter divalent metal transporter 1 in proximal jejunum after gastric bypass.

AIM: To describe the variation that divalent metal transporter 1 (DMT1) shows in patients after Roux-en-Y gastric bypass (RYGB) surgery. METHODS: Prospective and analytical study of DMT1 level at the brush border of proximal jejunum in patients having undergone RYGB surgery. The mucosa of proximal jejunum forming the gastrojejunal anastomosis was biopsied during surgery and after 6 mo later with an endoscopic biopsy. All the patients received precise instructions regarding feeding and nutritional supplementation. Both samples were processed at the same time by immunohistochemistry and western blot. Samples were analysed by a pathologist. For statistical analysis, the χ(2) and Wilcoxon tests were used. RESULTS: Sixteen patients were recruited, 13 of whom completed the study. Twelve were women. Average age and body mass index (BMI) were 44.1 and 40.4, respectively. Both body weight and BMI decreased significantly during the study period, with an average percent excess weight loss (%EWL) of 60% ± 13.3% and an average percent excess BMI loss (%EBMIL) of 79.6% ± 21.6%. Only two patients presented with mild anaemia 6 mo after surgery, but their ferritin levels stayed within normal ranges. Staining for DMT1 showed a significant increase in the cytoplasm of enterocytes located at the tips of the villi (χ(2) = 6.03; P = 0.049). Nevertheless, the total quantity of DMT1 decreased significantly (Z = 2.04; P = 0.04). Associated with these results, we observed a significant increase in goblet cells in the villi 6 mo postoperatively (Z = -2.47; P = 0.013). CONCLUSION: Six months after RYGB surgery, patients exhibit an increase in DMT1 expression in the enterocytes of the tips of the villi at the proximal jejunum.