Development of pva-natural biopolymer hydrogel incorporated with stingless bee honey for wound healing

Abstract

When the skin is injured, it would compromise the immune system as well as body’s homeostasis. Wound that fail to progress into the normal stage of healing is being recognized as delayed acute wound and chronic wound that could worsen the body condition. Honey is a well establish treatment for wound healing due to its antimicrobial, antioxidants, anti-inflammatory and high sugar contents. First of all, the stingless bee honey was evaluated via in vitro in term of antimicrobial and anti-inflammatory properties. 40% w/v concentration of honey displayed a good antimicrobial property against Staphylococcus aureus colonies since the honey able to inhibit their growth. In addition, the honey did not reduce the proinflammatory cytokines produced by LPS-activated macrophages. It is due to the immunomodulatory properties of honey that react towards the cytokines depending on the microenvironment of the wound. From the in vitro evaluation, 40% w/v concentration of honey was selected to be incorporated with hydrogel. Then, stingless bee-based hydrogel formulation was developed and characterized. Response surface model (RSM) which is consist of factorial design and central composite design was used to develop and optimized the hydrogel. Then, the characterization of the formulation was studied in term of hydrophilicity, polymerization, water vapor transmission rate (WVTR), rheological, drug release, microbial limit test, antimicrobial, stability and interaction between honey and the excipient by using Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR). Formulation 3 displayed a good reaction towards the selected response. Formulation 3 hydrogel has a good swelling ability which could provide a good moisturizing condition to the wound. Formulation 3 exhibited a good WVTR where the value is lower than control formulation. A higher WVTR cause the wound to dry rapidly. In rheological properties, Formulation 3 displayed a clear LVR line while in ATR-FTIR test, there was no substantial interaction observed in comparison with blank hydrogel. In addition, the release profile in Formulation 3 followed diffusion-controlled mechanism where the delivery of the honey is consistent throughout the time. Then, in term of microbial activity, Formulation 3 exhibited a good antimicrobial property and free from pathogenic microorganism. Finally, from the accelerated stability data, Formulation 3 was stable throughout storage period. For in vivo study, the blank and honey hydrogel were safe to use on the skin of the rabbit. The healing in honey hydrogel treated group was significantly (p<0.05) faster than no treatment group as shown in wound closure percentage and histological assessment. In honey hydrogel treated group, the amount of collagen deposited is abundant and the structure of fibroblast is well organized, this indicated at the end of the animal study, the wound has entered the remodelling phase compared with the no treatment group that still in proliferation phase. Based on all of these results, there are a lot of promising properties of stingless bee honey-based hydrogel such as good hydrophilicity, elasticity, microbial safety, reliable release profile as well as efficacy in wound healing treatment. Hence, it can be concluded that stingless bee honey-based hydrogel has a high potential to be a good wound dressing.