Composite Scaffolds Based on Bacterial Cellulose for Wound Dressing Application.

Wound dressing materials fabricated using biocompatible polymers have become quite relevant in medical applications, and one such material is bacterial cellulose (BC) with exceptional properties in terms of biocompatibility, high purity, crystallinity (∼88%), and high water holding capacity. However, the lack of antibacterial activity slightly restricts its application as a wound dressing material. In this work, polycaprolactone (PCL) was first impregnated into the BC matrix to fabricate flexible bacterial cellulose-based PCL membranes (BCP), which was further functionalized with antibiotics gentamicin (GEN) and streptomycin (SM) separately, to form wound dressing composite scaffolds to aid infectious wound healing. Fourier transform infrared spectroscopy (FT-IR) results confirmed the presence of characteristic PCL and cellulose peaks in the composite scaffolds at 1720 cm-1, 3400 cm-1, and 2895 cm-1, respectively, explaining the successful interaction of PCL with the BC matrix, which is further corroborated by scanning electron microscopy (SEM) images. X-ray diffraction (XRD) studies revealed the formation of highly crystalline BCP films (∼86%). In vitro studies of the BC and BCP scaffolds against baby hamster kidney (BHK-21) cells revealed their cytocompatible nature; also the wettability studies indicated the hydrophilicity of the developed scaffolds, qualifying the main criterion in wound dressing applications. Energy dispersive X-ray analysis (EDX) of the drug loaded scaffolds showed the presence of sulfur in the composites. The prepared scaffolds also exhibited excellent antimicrobial activity against Escherichia coli and Staphylococcus aureus. The release profiles initially indicated a burst release (6 h) followed by controlled release of GEN (∼42%) and SM (∼58%) from the prepared scaffolds within 48 h. Hence, these results interpret that the prepared drug-functionalized cellulosic scaffolds have great potential as a wound dressing material in biomedical applications.

Development of antioxidant-rich edible active films and coatings incorporated with de-oiled ethanolic green algae extract: a candidate for prolonging the shelf life of fresh produce.

The concept of sustainability and the substitution of non-biodegradable packaging using biodegradable packaging has attracted gigantic interest. The objective of the present study was to revalorize the biowaste "de-oiled green algae biomass (DAB)" of Dunaliella tertiolecta using a green approach and the development of biodegradable chitosan (CS)-based edible active biocomposite films and coatings for prolonging the shelf life of fresh produce. Ultrasound-assisted green extraction was conducted using food-grade solvent ethanol for obtaining the bio-actives, namely "crude algae ethanolic extract (CAEE)" from DAB. The edible films (CS/CAEE) and coating solutions were developed by incorporating CAEE with varying concentrations (0 to 28%). The CAEE was subjected to MALDI-TOF-MS, NMR, and other biochemical analyses, and was found to be rich in DPPH antioxidant activity (∼40%). The CS/CAEE films were fabricated using a solvent casting method and characterized by several biochemical and physicochemical (FESEM, TGA, FTIR, XRD, WVP, UTM, and rheological) characterization techniques. The addition of CAEE into the CS matrix reduced the maximum film transparency (∼20%), water vapor permeability (∼60%); improved the crystallinity (∼24%), tensile strength (∼25%), and antioxidant activity (∼27%); and exhibited UV-Vis blocking properties as compared to the control film. Besides, the developed coating solutions and CAEE showed biocompatibility with BHK-21 fibroblast cells and antimicrobial activity against common food pathogens. The developed coating solution was applied on green chilli using a dipping method and stored at ambient temperature (25 ± 2 °C, 50-70 % RH) for 10 days. The shelf life of chillies was extended without altering the quality as compared to uncoated green chillies. Therefore, the formulated coating could be applicable for prolonging the shelf life of fresh produce.

Prodigiosin-Loaded Poly(lactic acid) to Combat the Biofilm-Associated Infections.

Poly(lactic acid) (PLA) is an emerging biobased implant material. Despite its biocompatibility and the aseptic procedures followed during orthopedic surgery, bacterial infection remains an obstacle to implementing PLA-based implants. To tackle this issue, prodigiosin-incorporated PLA has been developed, which possesses improved hydrophobicity with a contact angle of 111 ± 1.5°. The degradation temperature of the prodigiosin is 215 °C, which is more than the melting temperature of PLA, which supports the processability and sterilization of the PLA-based implants without any toxic gases. Further, prodigiosin improves the transparency of PLA and acts as a nucleation site. The spherulite density increases three times compared to that of neat PLA. The inherent methoxy group of prodigiosin is an active site responsible for the inhibition of bacterial attack and biofilm formation. The in vitro study on biofilm formation shows excellent inhibition activity against implant-associated pathogens such as Klebsiella aerogenes and Staphylococcus aureus.

End-of-life evaluation and biodegradation of Poly(lactic acid) (PLA)/Polycaprolactone (PCL)/Microcrystalline cellulose (MCC) polyblends under composting conditions.

The present study evaluates biodegradation of the polyblends of poly(lactic acid) (PLA), polycaprolactone (PCL) and microcrystalline cellulose (MCC) in different compositions and comparison of the properties of those blends with that of neat PLA and neat PCL. The samples were melt extruded and blended to evaluate the environmental fate of the polyblends under simulated composting conditions following the standard ASTM International D5338-15 protocol. It was seen that blends with a higher concentration of PCL and MCC in the PLA matrix showed higher carbon mineralization percentage in comparison to the blends having low PCL and MCC components. Molecular weight analysis of the samples showed a decrease in their weight due to chain scission mechanism leading to the formation of intermediates. Analytical techniques revealed the formation of microbial biofilms on the blended biopolymeric surfaces. Field emission scanning electron microscopy showed the formation of fibril-like structures by PLA, and the formation of rough patches on the PCL surface re-confirmed biodegradation of the samples. This work fuels interest in the material characterization of PLA/PCL/MCC based polyblends and helps in tuning the biodegradability of the studied samples according to the demands.