Study Of A Hydrogel For Photodynamic Therapy In The Treatment Of Acne Vulgaris

Acne vulgaris is a kind of chronic skin disease with extremely high incidence and extensive pathogenesis.The main reason is bacterial colonization such as Propionibacterium acnes(P.acnes)and Staphylococcus aureus(S.aureus).Antibiotic application in clinic showed bacterial resistance,which results in lower applicability of treatments.Photodynamic therapy(PDT)is a promising physiotherapy strategy,which is widely applied for cancer,oral diseases and various skin diseases,and it would overcome the current disadvantages of treatment in the process of acne.Although Toluidine blue O(TBO)as a phenothiazine photosensitizer has been widely applied in antimicrobial photodynamic therapy,there is not a suitable dosage form containing TBO could used in the clinical treatment of acne.In this experiment,antibacterial activity as the main reference index,an optimal formulation of TBO hydrogel was obtained by single factor studies and response surface methodology.Subsequently,the rheological property,stability(appearance,pH,antibacterial activity and viscosity),in vitro release and spreadability of the optimal TBO hydrogel formulation were investigated,and the antibacterial activity against P.acnes was compared.Finally,the safety of optimal TBO hydrogel formulation with PDT was evaluated by the toxic experiment on normal skin fibroblasts.The results in single factor and response surface methodology experiments showed that the optimal formulation including 0.5%(w/v)carbomer 934 as the gel matrix,0.5%(v/v)tween 80 as the penetration enhancer,TBO concentration of 0.01 mg/mL,0.5%(v/v)ethanol concentration as solvent and the mass ratio of NaOH to carbomer of 0.4(w/w).The appropriate irradiation time is 40 s;The rheological behavior studies demonstrated the TBO hydrogel had pseudoplastic behavior;The stability test showed the optimal TBO hydrogel,which stored at 4?,25? and 40?,have no obvious changes in appearance,pH,antibacterial activity and viscosity It showed stable.In vitro release studies,the TBO of the hydrogel showed fast release rate.After 4 h,the amout of release is 51.28%and keep stable basically after 6 h;In the spreadability test,the novel hydrogel is easiness and uniformity of application compared with first-line clinical preparations;In the antibacterial activity studies,TBO hydrogel with PDT has ideal antibacterial effect on P.acnes.In addition,it has no resistance and severe side-effect compared with antibiotics;The cytotoxicity results showed that the TBO hydrogel with PDT is safety.Therefore,this study designed and optimized a novel TBO hydrogel.It could effectively against pathogenic bacteria such as Propionibacterium acnes and Staphylococcus aureus,and could cause no damage to normal skin cells.It might be safety and effectivety.It would extremely improve the current situation of PDT for treating acne vulgaris and expand the effective treatment methods of acne vulgaris,even provide reliable theory basis for clinical experiments.