Porous Deproteinized Natural Rubber Film Loaded with Silver Nanoparticles for Topical Drug Delivery

The work demonstrated the use of natural rubber for topical drug delivery. The first objective was to fabricate a porous deproteinized natural rubber film loaded with silver nanoparticles. Characterizing and assessing its formulation was the second objective. Surface pH, mechanical properties, swelling ratio, erosion, moisture vapor transmission rate, scanning electron microscopy/energy dispersive X-ray analysis, and X-ray diffraction were evaluated. In vitro studies and antibacterial activity were assessed. It was discovered that silver nanoparticles could enter the film and that their concentrations ranged between 7.25 and 21.03 µg/cm2. The pH of the film's surface was 7.00. The mechanical properties of the film with silver nanoparticle loading differed from the blank film. After adding silver nanoparticles, the film eroded faster than before, but the swelling ratio was not affected significantly. Increased time utilization had an impact on the moisture vapor transmission rate of the film. Silver nanoparticles released easily from the film while there was less permeability. The dead pig-ear skin had significant silver nanoparticle accumulation. Potent antibacterial activity was seen in the film containing silver nanoparticles. The silver nanoparticle-loaded film may be used as a wound dressing for a topical film that promotes wound healing while also protecting the area from infection.

Evaluation of in vivo bond strength and skin irritation test for new skin adhesive

Objectives

This study developed a new skin-deproteinized natural rubber latex (DNRL) silicone adhesive for adhering to silicone prostheses and compared the properties with a commercial Daro-Hydrobond adhesive.

Materials and methods

The new DNRL skin adhesive formulation was made from non-vulcanized natural rubber-based adhesives consisting of DNRL, 20% polyvinyl alcohol, cumarone resin, 2% methylcellulose, and Wingstay L. The peel bond strength of the adhesives was tested using a 90-degree peel test. Biocompatibility was accessed using in vitro keratinocyte cell viability. Animals (rabbits) and humans were tested for skin irritation tests. Results were analyzed using SPSS Version 24 and compared between the two adhesives.

Results

The peel bond strength of the new DNRL skin adhesive was 103.61 ± 23.18 N/m whereas that of the Daro-hydrobond adhesive was 131.52 ± 21.72 N/m. There was no significant difference (p>0.05) between the peel bond strengths of the two test adhesives. Cell proliferation under the DNRL skin adhesive-soaked medium showed higher cell viability than the positive control (p<0.05). The DNRL skin adhesive produced moderate erythema and edema on rabbit skins, however, the skin lesions recovered within 14 days. Two volunteers showed mild irritation at the first hour of the contact which was reduced within an hour without any therapy. The patient satisfaction with the DNRL skin adhesive ranged from slightly satisfied to completely satisfied.

Conclusion

The new DNRL skin adhesive showed comparable peel bond strength and patient satisfaction to those of commercial adhesives. The adhesive was biocompatible and can be used carefully.

Synthesis of epoxidized natural rubber grafted with hyaluronic acid for the development of biomaterials

Natural Rubber (NR), extracted from Hevea brasiliensis rubber trees, is a biocompatible biopolymer with properties that support in the tissue repair process. However, its biomedical applications are limited due to the presence of allergenic proteins, hydrophobicity, and unsaturated bonds. To overcome these limitations and contribute to the development of new biomaterials, this study aims to deproteinize, epoxidize, and subject NR to copolymerization by grafting with hyaluronic acid (HA), which is widely recognized for its bioactive properties in the medical field. The deproteinization, epoxidation, and graft copolymerization through the esterification reaction were confirmed by Fourier Transform Infrared Spectroscopy and Hydrogen Nuclear Magnetic Resonance Spectroscopy analysis. Thermogravimetry and Differential Scanning Calorimetry demonstrated that the grafted sample exhibited a lower degradation rate and a higher glass transition temperature, indicating strong intermolecular interactions. Moreover, contact angle measurement revealed that the grafted NR exhibited a high hydrophilic character. The results obtained suggest the formation of a novel material with great potential for application in biomaterials involved in tissue repair processes.

Effect of glycerol and dibutyl phthalate on modified natural rubber latex based drug delivery systems

The work highlights the impact of the incorporation of two pharmaceutical plasticizers viz.; glycerol (GLY; hydrophilic) and dibutyl phthalate (DBP; hydrophobic) on the controlled drug release features of a deproteinised natural rubber latex (DNRL) -based matrix. The effects of the plasticizers on the mechanical properties, glass transition temperature (T_g), water absorption behaviour and porosity of DNRL have been initially investigated. The plasticized membranes have been found to show a hemolysis percentage (HP) of <5 %; confirming its compatibility with human blood. The potential of the modified DNRL membranes to function as drug carriers have been examined with metformin hydrochloride (MET) as a model drug.

Formulation Development and Pharmaceutical Evaluation of Lysiphyllum strychnifolium Topical Patches for Their Anti-inflammatory Potential

Topical drug delivery systems are interesting and popular dosage forms for formulation development. Thai herbs are used in alternative medicine to treat patients suffering from severe illnesses. They have significant economic and cultural value in Thailand. This work prepared Thai herbal topical patches of Lysiphyllum strychnifolium stem extracts using pectin and Eudragit^® NM 30D, and glycerin as a plasticizer. Astilbin was selected as a chemical marker in L. strychnifolium stem extracts. The L. strychnifolium stem extracts showed a statistically significant decrease in nitrate accumulation. The various properties of Thai herbal topical patches were not significantly different from blank patches. However, the trends of the properties depended on the amount of Eudragit^® NM 30D. All ingredients were homogeneously mixed in Thai herbal topical patches and showed a smooth and compact film. The astilbin content was found in a range of 52.72-63.36 μg/cm². The in vitro release of astilbin depended on the amount of Eudragit^® NM 30D. The kinetics of astilbin release were fitted to the Korsmeyer-Peppas model. The astilbin showed low permeation; thus, polyethylene glycol 400 was used as a permeation enhancer. Polyethylene glycol 400 could increase the permeation rates of astilbin and the cumulative amount of astilbin in pig skin. This would be suitable for preparing the Thai herbal topical patches and could be developed for pharmaceutical and herbal products.