Defect-Rich SnO₂ Nanofiber as an Oxygen-Defect-Driven Photoenergy Shield against UV Light Cell Damage

Usually, most studies focus on toxic gas and photosensors by using electrospinning and metal oxide polycrystalline SnO₂ nanofibers (PNFs), while fewer studies discuss cell-material interactions and photoelectric effect. In this work, the controllable surface morphology and oxygen defect (V_O) structure properties were provided to show the opportunity of metal oxide PNFs to convert photoenergy into bio-energy for bio-material applications. Using the photobiomodulation effect of defect-rich polycrystalline SnO₂ nanofibers (PNFs) is the main idea to modulate the cell-material interactions, such as adhesion, growth direction, and reactive oxygen species (ROS) density. The V_O structures, including out-of-plane oxygen defects (op-V_O), bridge oxygen defects (b-V_O), and in-plane oxygen defects (ip-V_O), were studied using synchrotron analysis to investigate the electron transfer between the V_O structures and conduction bands. These intragrain V_O structures can be treated as generation-recombination centers, which can convert various photoenergies (365-520 nm) into different current levels that form distinct surface potential levels; this is referred to as the photoelectric effect. PNF conductivity was enhanced 53.6-fold by enlarging the grain size (410 nm²) by increasing the annealing temperature, which can improve the photoelectric effect. In vitro removal of reactive oxygen species (ROS) can be achieved by using the photoelectric effect of PNFs. Also, the viability and shape of human bone marrow mesenchymal stem cells (hMSCs-BM) were also influenced significantly by the photobiomodulation effect. The cell damage and survival rate can be prevented and enhanced by using PNFs; metal oxide nanofibers are no longer only environmental sensors but can also be a bio-material to convert the photoenergy into bio-energy for biomedical science applications.