Effects of montmorillonite on the loading and release of Piper betle L. extract applied for wound dressing based on chitosan/polyvinyl alcohol.

In this study, we investigate the influence of montmorillonite (MMT) on the loading and release of Piper betle L. extract (PLE)-a medicinal herb containing active secondary metabolites with antibacterial, antioxidant, and anti-inflammatory effects. MMT (1 %, 3 %, 5 %) was blended into the chitosan/polyvinyl alcohol (CS/PVA) biocomposite film by the solution evaporation method, and then PLE was loaded onto this biocomposite using the immersion method. The tensile strength and the ability to absorb exudates of the CS/PVA film improved with the increase in MMT content. The MMT 3 % film was considered to have the best properties: good mechanical properties with a tensile strength of 27.44 ± 0.27 MPa and elongation at break of 14.57 ± 0.30 %, potential for wound dressing due to its ability to absorb wound exudate (swelling degree 61.70 ± 0.30 %) and a suitable water vapor transmission rate (1999 ± 47 g/m2·d). The presence of MMT (1 %, 3 %, 5 %) in the CS/PVA film led to an increase in the PLE loading efficiency of the films compared to the film without MMT, up to 1.65, 1.73, and 1.87 times, respectively. The MMT 3 % and 5 % films also exhibited a sustained PLE release effect for up to 24 h. MMT increased PLE bioavailability through bioactivity tests: antibacterial activity against both E. coli and S. aureus, antioxidant activity, effective healing of 2nd-degree burn wounds, and biocompatibility with the L929 fibroblasts cell line. The combination of physicochemical properties and biological activities proved that the MMT/PLE drug delivery system based on the CS/PVA biocomposite is promising for wound dressing.

Removal of Cu (II) by calcinated electroplating sludge.

Electroplating sludge consists of various heavy metal oxides, which may be utilized as adsorbent to remove Cu (II) present in aqueous environment. This study evaluated the adsorption performance of calcinated electroplating sludge. The adsorption isotherm based on Langmuir equation proved that calcinated electroplating sludge had a higher adsorption performance than raw electroplating sludge, with maximum adsorption capacity 92 mg/g and 76.34 mg/g, respectively. Findings of the conducted kinetic study revealed that both surface adsorption and intra-particular diffusion were involved during the adsorption process. Moreover, the comparison between the experimental and calculated data of equilibrium adsorption capacity demonstrated that the pseudo second-order kinetic equation fitted well with 38.31 mg/g of calcinated sludge and 33.66 mg/g of raw sludge, approximate to real-world data. Furthermore, adsorption mechanism research demonstrated that while OH group plays a vital role in raw sample, Ca2+, in addition to OH group, was involved in ion exchange in calcinated sample.

Type IV pilin is glycosylated in Pseudomonas syringae pv. tabaci 6605 and is required for surface motility and virulence.

Type IV pilin (PilA) is a major constituent of pilus and is required for bacterial biofilm formation, surface motility and virulence. It is known that mature PilA is produced by cleavage of the short leader sequence of the pilin precursor, followed by methylation of N-terminal phenylalanine. The molecular mass of the PilA mature protein from the tobacco bacterial pathogen Pseudomonas syringae pv. tabaci 6605 (Pta 6605) has been predicted to be 12 329 Da from its deduced amino acid sequence. Previously, we have detected PilA as an approximately 13-kDa protein by immunoblot analysis with anti-PilA-specific antibody. In addition, we found the putative oligosaccharide-transferase gene tfpO downstream of pilA. These findings suggest that PilA in Pta 6605 is glycosylated. The defective mutant of tfpO (ΔtfpO) shows reductions in pilin molecular mass, surface motility and virulence towards host tobacco plants. Thus, pilin glycan plays important roles in bacterial motility and virulence. The genetic region around pilA was compared among P. syringae pathovars. The tfpO gene exists in some strains of pathovars tabaci, syringae, lachrymans, mori, actinidiae, maculicola and P. savastanoi pv. savastanoi. However, some strains of pathovars tabaci, syringae, glycinea, tomato, aesculi and oryzae do not possess tfpO, and the existence of tfpO is independent of the classification of pathovars/strains in P. syringae. Interestingly, the PilA amino acid sequences in tfpO-possessing strains show higher homology with each other than with tfpO-nonpossessing strains. These results suggest that tfpO and pilA might co-evolve in certain specific bacterial strains.