| Skin is the largest part of the body responsible to play many key roles such as defence from pathogen and toxins,thermostatics,protection from excessive loss of water,and other homeostatic functions.Skin is the most exposed organ usually faces many types of dermatological inconveniences such as injuries,surgeries,burns,traumas,etc.Skin is provided with an inbuilt mechanism of self-healing after going through distinct hence overlapping phases of wound healing but the healing process may be delayed or completely abolished due to multiple external and internal factors.These factors may interrupt the healing process leading to the development of chronic non-healing wounds.Many factors such as infection,obesity,diabetes,aging,hypoxia,ischemia,etc can be detrimental for a chronic wound.Among these,infection and diabetes are major factors.Diabetes is one of the most prevalent causes of delayed wound healing due to the persistent inflammatory cycle.The delayed closure of the wound,often,increase the risk of skin infection.The systemic use of antibiotics has a limited impact on skin infection.Moreover,the systemic use of a conventional antibiotic may increase the risk of developing resistance along with destroying useful microflora in the digestive tract.Therefore,the direct topical delivery of alternate antimicrobial agents can be useful in mitigating skin infections.Managing a diabetic wound,therefore,demands the construction of active wound dressing capable to protect the wound from microbial invasion as well possess specific bioactivities which can influence the newly developing tissues at the cellular and molecular level to improve the wound healing through terminating inflammatory cycle,granulation formation,angiogenesis,epithelialization,and collagen deposition.Although many active wound dressings have been developed but constructing a multifunctional wound dressing to treat diabetic wounds remains a significant challenge.The basic aim of the study was to construct different types of active wound dressings using electrospinning technology,to combat skin infection as well as induce multiple bioactivities to promote as well as enhance the quality of healing.Three different types of the wound dressing,composed of electrospun nanofibers,were constructed and extensively characterized for various physicochemical and biological attribution along with in vivo trials.In the first study,an active wound dressing was constructed using Poly(L-lactide-cocaprolactone)and silk fibroin(PLCL/SF)polymers loaded with oregano essential oil(OEO).OEO is a promising natural compound with marked antibacterial,antioxidant and antiinflammatory activities.The topical delivery of OEO may result in lower therapeutic efficacy and irritation to the skin.Moreover,OEO is a volatile compound results in instability as well.To overcome these drawbacks,we successfully encapsulated OEO in PLCL/SF nanofibers membrane(NF)and achieved the encapsulation efficiency(%)up to 59.14±0.58.The fabricated membranes were undergone through physicochemical as well as biological evaluation.SEM characterization revealed that OEO could be successfully encapsulated maintaining a smooth profile of NF.The biocompatibility of the NF membrane was confirmed by cytotoxicity assay.Antibacterial results indicated that OEO loaded NF membranes is highly active against both gram-positive and gram-negative bacteria.The result revealed that 5% is the optimized concentration of OEO capable to completely inhibit bacterial growth.Moreover,the NF membranes were evaluated for their in vivo wound healing potential.The results confirmed that OEO loaded NF membrane was not only capable to accelerate the wound contraction but also enhanced the quality of wound healing confirmed through histology analysis.H&E and Masson's trichrome staining indicated the neo-epithelialization,granulation tissue formation,angiogenesis,and collagen deposition in a group treated with PLCL/SF/5%OEO.Another NF membrane was constructed using poly(lactide-co-glycolic acid)(PLGA)/SF combination encapsulating various concentrations of ZnO nanoparticles.ZnO nanoparticles(NP)are known for their antibacterial,antioxidant,and anti-inflammatory activities.Moreover,ZnO NP can stimulate cell migration,re-epithelialization,and angiogenesis.All these attributes are highly relevant to the wound healing process.Local administration of ZnO NP to wound can be achieved after encapsulating in nanofibers through electrospinning.We hypothesized that PLGA/ SF nanofibers-based delivery of ZnO to maintain the bioavailability of NP on the wound area and synchronization with unique structural features of electrospun nanofibers can stimulate the wound closure,re-epithelialization,collagen deposition,cellular migration,proliferation,and angiogenesis.In this study,we fabricated the PLGA/SF(PS)nanofibrous(NF)membranes with and without ZnO NP and were extensively characterized by various physicochemical and biological attributions.SEM revealed the smooth fibers and ZnO concentration-dependent increase in fiber diameter.TEM also confirmed the encapsulation of ZnO NP in the polymer matrix.The successful loading of ZnO was further confirmed by XRay Diffraction(XRD)and thermogravimetric analysis(TGA).Furthermore,mechanical testing revealed the ZnO concentration-dependent increase in tensile strength.Moreover,in vitro cell culture confirmed the biocompatibility of the fabricated NF membranes.A mild antioxidant activity was also observed,mainly due to the presence of SF.The turbidity measurement method was employed to assess the antibacterial potential of NF membranes.Results revealed that there was a ZnO concentration-dependent increase in antibacterial activity.During in vivo trial,PLGA/SF/3% ZnO(PSZ3)NF membrane not only facilitated the early wound closure but also remarkably enhanced the quality of wound healing confirmed through histopathological analysis.Re-epithelialization,granulation tissue formation,collagen deposition,and angiogenesis are some of the key parameters significantly boosted by ZnO loaded composite NF membranes.Finally,a new loading strategy was employed to load both OEO and ZnO NP into PLCL for their co-delivery at the wound site.Physicochemical characterization revealed the successful fabrication of nanofibers loaded with two bioactive substances.In vitro evaluation confirmed the strong anti-bacterial and anti-oxidant activities.Moreover,the proposed NF membranes supported cell adhesion and proliferation.In vivo wound healing evaluation confirmed the potential of bioactive NF membranes in promoting the early wound contraction.The angiogenic was highly induced by the bioactive NF membranes via vascular endothelial growth factor(VEGF)expression.Moreover,the proposed NF membrane successfully terminated the inflammatory cycle by decreasing the pro-inflammatory cytokines via down-regulating the interleukin-6(IL-6)and matrix metalloproteinases-9(MMP-9).Based on in vitro and in vivo evaluation,we conclude that the fabricated wound dressing can be used to treat the infected wound.Moreover,the synergistic activity of OEO and ZnO,demonstrated by PLCL/Z/E NF membrane,makes it a highly promising nano wound dressings for the healing of chronic wounds,especially diabetic wounds. |
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