Photodynamic inactivation of different pathogenic bacteria on human skin using a novel photosensitizer hydrogel

Abstract

Background The colonization of skin with pathogenic, partially antibiotic‐resistant bacteria is frequently a severe problem in dermatological therapies. For instance, skin colonization with Staphylococcus aureus is even a disease‐promoting factor in atopic dermatitis. The photodynamic inactivation (PDI) of bacteria could be a new antibacterial procedure. Upon irradiation with visible light, a special photosensitizer exclusively generates singlet oxygen. This reactive oxygen species kills bacteria via oxidation independent of species or strain and their antibiotic resistance profile causing no bacterial resistance on its part. Objective To investigate the antibacterial potential of a photosensitizer, formulated in a new hydrogel, on human skin ex vivo. Methods The photochemical stability of the photosensitizer and its ability to generate singlet oxygen in the hydrogel was studied. Antimicrobial efficacy of this hydrogel was tested step by step, firstly on inanimate surfaces and then on human skin ex vivo against S. aureus and Pseudomonas aeruginosa using standard colony counting. NBTC staining and TUNEL assays were performed on skin biopsies to investigate potential necrosis and apoptosis effects in skin cells possibly caused by PDI. Results None of the hydrogel components affected the photochemical stability and the life time of singlet oxygen. On inanimate surfaces as well as on the human skin, the number of viable bacteria was reduced by up to 4.8 log10 being more effective than most other antibacterial topical agents. Histology and assays showed that PDI against bacteria on the skin surface caused no harmful effects on the underlying skin cells. Conclusion Photodynamic inactivation hydrogel proved to be effective for decolonization of human skin including the potential to act against superficial skin infections. Being a water‐based formulation, the hydrogel should be also suitable for the mucosa. The results of the present ex vivo study form a good basis for conducting clinical studies in vivo.

Light-Activated Antibacterial Ethylcellulose Electrospun Nanofibrous Mats Containing Fluorinated Zn(II) Porphyrin

“…So, it can help to combat several resistant strains and mixed infections, especially in the case of chronic wounds and also common dermatosis (e.g., acne, rosacea), avoiding antibiotics and tackling antimicrobial resistance. 22 A plausible approach to attach PSs to various polymeric materials is the electrospinning technique. This is a relatively inexpensive, versatile, and straightforward technology based on an electrohydrodynamic process that occurs when a high voltage is applied to a polymeric solution, enabling the formation of the Taylor cone at the tip of the needle.…”

“…The development of antimicrobial photodynamic polymeric materials has become a trending topic in recent years. − In this regard, several research works propose the PDI as a promising tool for dermal applications developing skin patches. − This therapy type allows the inactivation of different microbials which provoke infection after damage or injury in the skin and soft tissue, retarding the wound healing process and skin regeneration. So, it can help to combat several resistant strains and mixed infections, especially in the case of chronic wounds and also common dermatosis (e.g., acne, rosacea), avoiding antibiotics and tackling antimicrobial resistance …”