Preparation And Evaluation Of Chitosan/Phospholipid Self-assembled Nanoparticles For The Treatment Of Epidermal Primary Bacterial Infection

Due to the breakage of skin,environmental bacteria can invade the body and cause severe sepsis,systemic multi-organ failure,and possibly even life-threatening conditions.As the primary and most effective antibacterial drugs,antibiotics have been made into a variety of drug formulations for the treatment of topical epidermal bacterial infections such as creams,gels,emulsions,ointments.Though significant progresses have been achieved by using these traditional formulations in clinical treatment,many problems remained to be solved to further accelerating their wide applications in practical applications.For instance,the retention and retention time of drugs encapsulated in traditional formulations to the epidermis is relatively low,resulting in poor therapeutic efficacy and requiring high doses and repeated applications in a day.Moreover,the use of traditional formulations often leads to excessive absorption of drugs into the dermis and the blood circulation,which causes many side effects.In recent years,the application of nano drug delivery systems has attracted widespread attention in the field of treatment of epidermal bacterial infections.Therefore,to solve the above problems,lecithin/chitosan nanoparticles(LCNPs)with efficient epidermal delivery capability was designed and constructed for the treatment of epidermal bacterial infections.First,chitosan nanoparticles(CNPs)were prepared by electrostatic adsorption.CNPs self-assemble with lecithin to form LCNPs.The preparation of LCNPs was optimized by prescription through single-factor experiments and central combined rotational design method,and the best preparation method was screened with the particle size as the index of investigation.The average particle size of LCNPs prepared by the optimized preparation method was 325.9±7.4 nm,and the zeta potential was 26.6±1.2 m V.The batch-to-batch reproducibility was good and the prescription process was stable and feasible.The physical and chemical properties of the LCNPs were investigated systematically,such as size,drug loading,entrapment efficiency and in vitro release,by using laser particle size measurement,transmission electron microscopy,scanning electron microscopy,infrared spectroscopy,ultraviolet absorption spectroscopy and dynamic dialysis.The results showed that the prepared nanoparticles were homogeneous in morphology,stable in morphology,suitable in size,a monodisperse spherical structure.Ciprofloxacin hydrochloride(CIP)has broad-spectrum antibacterial properties and good bactericidal effects.However,some common adverse reactions of CIP include abdominal discomfort,pain,diarrhea,nausea.CIP was selected as an antibacterial model drug.CIP was encapsulated in LCNPs,and the drug was delivered to the epidermis to exert the antibacterial ability of the epidermis and reduce the side effects of the drug.First,explore the encapsulation and drug loading of LCNPs.The results show that the maximum encapsulation efficiency of CIP is 41.65%±1.25%,and the drug loading is7.53%±0.25%,and the in vitro release characteristics of CIP were investigated,and the cumulative release was 93.81%±2.05%within 48 h.The drug release mechanism of CIP-LCNPs is analyzed by using the kinetic model.The results showed that the drug release was in accordance with the Korsmeyer-Peppas kinetic model,and the release index n of CIP-LCNPs was 0.32,which belonged to the Fick type release(<0.43).Therefore,the drug release mechanism was released into the lecithin layer first,then released into the release medium.Various methods were used to study the stability,biocompatibility,antibacterial properties and transdermal permeability in vitro.The study of long-term placement stability of LCNPs was studied different temperatures,and the results showed that the stability of LCNPs was better at 4℃.The biocompatibility of LCNPs was evaluated by hemolysis,cytotoxicity and skin irritation tests,and the results proved that LCNPs have good biocompatibility and biosafety.In vitro antibacterial performance was investigated by disc diffusion method,and the results showed that CIP-CNPs exhibited good in vitro antibacterial performance with the inhibition circle size of 1.89±0.06 cm and 2.92±0.03cm against S.aureus and E.coli,respectively.In addition,the skin permeability assay showed that the skin drug permeation of CIP-LCNPs was 8.01±0.51μg/cm~2,which was lower than that of commercially available CIP cream and commercially available CIP gel.In addition,the retention ratios of CIP in the epidermis to the dermis were quantitatively calculated,and the retention ratios of CIP in the epidermis to the dermis were 1.35,1.81,3.05,and 4.98 for commercially available CIP creams,commercially available CIP gels,CIP-CNPs,and CIP-LCNPs,respectively.The results indicated that LCNPs could effectively increase the retention of CIP in the epidermis,reduce CIP penetration through the dermis into circulation,increase the epidermal antimicrobial capacity,and avoid the occurrence of adverse reactions.On this basis,an animal model of epidermal wound infection was constructed to study its ability to promote wound healing in vivo.The results showed that the wounds treated with CIP-LCNPs showed good healing effect,and the degree of wound healing was 99.4%±0.2%after 5 days,which proved that the prepared CIP-LCNPs had good ability to promote the healing of epidermally infected wounds.The prepared of LCNPs can effectively localize the drug in the epidermal layer,increase the retention amount and retention time of the drug,and show good epidermal anti-infection effect,which provides a new idea and strategy for the treatment of epidermal bacterial infections.