Engineering hemin-loaded hyaluronan needle-like microparticles with photoprotective properties against UV-induced tissue damage.

This study aimed to develop hyaluronan (HA)-based hydrogel microparticles (MPs) loaded with hemin to address the limitations of traditional macroscale hydrogels. The objective is to design MPs such that they can modulate their physicochemical properties. Given the widespread use of ultraviolet C (UVC) light in various industries and the need for protective measures against accidental exposure, this study evaluated the potential of hemin-loaded MPs to protect human dermal fibroblasts from oxidative stress and cell death caused by UVC exposure. Multiple MP formulations were developed and analysed for size, surface charge, swelling behaviour, degradation rate, and radical scavenging capabilities, both with and without hemin loading. The most promising formulations were tested against UVC-exposed cells to assess cell viability, intracellular nitric oxide (˙NO) and reactive oxygen species levels, and protein carbonylation. The fabricated particles were in the form of microneedles, and the degree of their crosslinking and the role of hemin in the chemical crosslinking reaction were found to influence the surface charge and hydrodynamic diameter of the MPs. Increased crosslinking resulted in reduced swelling, slower degradation, and decreased hemin release rate. MPs with a higher degree of swelling were capable of releasing hemin into the culture medium, leading to enhanced bilirubin generation in dermal fibroblasts following cellular uptake. Pre-treatment with these MPs protected the cells from UVC-induced cell death, nitrosative stress, and protein carbonylation. These findings highlight the potential of the studied MPs to release hemin and to minimise the harmful effects of UVC on dermal fibroblasts.