Herein, polyvinyl alcohol-carboxymethyl cellulose (PVA-CMC) composite hydrogel membranes were prepared using solution-casting method, where citric acid (CA) was added as crosslinker in different ratios of (7, 10 and12 wt%). Attapulgite clay extracted from Northwestern Desert of Borg El-Arab, Egypt; was incorporated as nanofiller (1, 2, 4, and 5 wt%) into membranes for improving their mechanical/ thermal stability. Results revealed that, physicochemical properties of membranes e.g. swelling%, tensile strength and morphology of membranes affected significantly by different clay concentrations and citric acid crosslinker. Also, attapulgite clay with concentration 1 (wt%) enhanced mechanical strength of composite membranes, compared to other clay concentrations. Furthermore, protein adsorption %, hydrolytic degradation, hemolysis (%) and antimicrobial activity significantly affected by clay contents and CA concentrations. Four bacterial pathogens e.g. Candida albicans, Escherichia coli, Klebsiella pneumoniae, and Bacillus cereus were used for testing antimicrobial activity of prepared membranes. Results referred to increasing of clay contents led to a high hemolysis %; however, increasing CA concentration significantly reduced hemolysis %. Meanwhile, membranes with low clay contents offered the most effective resistance against tested microbes. These findings are referring to the ability of using PVA-CMC-attapulgite composite membranes crosslinked by CA as good candidate of biomaterials for dermal wound dressings.

Herein, polyvinyl alcohol-carboxymethyl cellulose (PVA-CMC) composite hydrogel membranes were prepared using solution-casting method, where citric acid (CA) was added as crosslinker in different ratios of (7, 10 and12 wt.%). Attapulgite clay extracted from Northwestern Desert of Borg El-Arab, Egypt; was incorporated as nanofiller (1, 2, 4, and 5 wt.%) into membranes for improving their mechanical/ thermal stability. Results revealed that, physicochemical properties of membranes e.g. swelling%, tensile strength and morphology of membranes affected significantly by different clay concentrations and citric acid crosslinker. Also, attapulgite clay with concentration 1 (wt.%) enhanced mechanical strength of composite membranes, compared to other clay concentrations. Furthermore, protein adsorption %, hydrolytic degradation, hemolysis (%) and antimicrobial activity significantly affected by clay contents and CA concentrations. Four bacterial pathogens e.g. Candida albicans, Escherichia coli, Klebsiella pneumoniae, and Bacillus cereus were used for testing antimicrobial activity of prepared membranes. Results referred to increasing of clay contents led to a high hemolysis %; however, increasing CA concentration significantly reduced hemolysis %. Meanwhile, membranes with low clay contents offered the most effective resistance against tested microbes. These findings are referring to the ability of using PVA-CMC-attapulgite composite membranes crosslinked by CA as good candidate of biomaterials for dermal wound dressings.

No abstract

Immobilized microorganisms especially bacteria are most used rather than free cells to be protected from the environmental conditions when being used for the bioremediation of environmental pollutants. Herein, two marine’s bacterial isolates were tested for their ability to decompose crude oil. The optimum conditions for effective bacterial degradation e.g., pH, temperature, and inoculum size were investigated. PVA-alginate-clay composite hydrogel beads with different types of incorporated mineral clays were prepared and tested as bacterial carrier for potential bioremediation. Synthesized composite hydrogels were physico-chemically characterized by FTIR, SEM, and thermal analyses. Results showed that, embedded degrading bacteria in PVA-alginate beads recorded degradation rates as 74 and 66.6% for both tested bacterial isolates (S and R) compared to 61.2 and 53% degradation rates by free cells, respectively. Where, attapulgite clay-containing beads recorded maximum degradation% as 78.8 and 75% for both bacterial isolates, when added to immobilization matrices and these percentages could be enhanced under optimal conditions. The 16S rRNA gene of the two marine oils degrading bacterial isolates were amplified and sequenced, where both isolates were identified as Pseudomonas stutzeri and Rhodococcus qingshengii with submitted accession numbers of ON908963 and ON908962, respectively. These results are referring to the ability of using both tested isolates for crude oil bioremediation process and embedded them into PVA-alginate-clay beads as hydrogel carrier under the optimum conditions.