Khan, A. U. | bioRxiv Science

bioRxiv2025

Household LED Light-Mediated Photodynamic Therapy for Effective Inhibition of Multidrug-Resistant Staphylococcus aureus

This study investigates the efficacy of toluidine blue O (TBO) and curcumin as photosensitizers for photodynamic therapy (PDT) against Staphylococcus aureus using a household LED bulb as the light source. Antibacterial and anti-biofilm activities were evaluated via colony-forming unit (CFU) and Congo red assays, while reactive oxygen species (ROS) generation was quantified using DCFH-DA dye. Confocal laser scanning microscopy (CLSM) was employed to assess live/dead bacterial cell ratios, and an in vivo skin abrasion model in Wistar rats was used to validate therapeutic outcomes. The CFU assay revealed substantial bacterial reductions, achieving 4.85 log CFU/ml at 10 minutes for TBO and 2.81 log CFU/ml at 15 minutes for curcumin. Extracellular polymeric substance (EPS) production decreased by 96.22% with TBO and 48.98% with curcumin, accompanied by enhanced ROS generation. CLSM confirmed a higher dead-to-live cell ratio following PDT. In vivo results, supported by histopathological examination and cytokine expression profiling, further demonstrated the effectiveness of TBO- and curcumin-mediated PDT under LED light. Overall, these findings highlight the potential of readily available household LED bulbs as an accessible and efficient light source for PDT, offering robust antimicrobial activity against S. aureus.

microbiology↗

bioRxiv2025

Neural dynamics of proactive and reactive cognitive control in medial and lateral prefrontal cortex

Goal-directed behavior requires adjusting cognitive control to both react to and prepare for conflict. Previous work indicates theta oscillations and population activity in dorsomedial prefrontal cortex (dmPFC) and dorsolateral prefrontal cortex (dlPFC) are critical for reactive control. However, the neural mechanisms supporting proactive control are less clear. Here, we investigated the neural basis of behavioral adaptations when control is prepared in anticipation of conflict using intracranial EEG (iEEG) in dmPFC and dlPFC during a Stroop task where conflict frequency was manipulated across blocks. We observed canonical conflict-driven increases in dmPFC theta and in dmPFC and dlPFC local population activity, as indexed by high frequency activity (HFA). Conflict also suppressed theta power in both regions after the response, accentuated a pre-response beta desynchronization selectively in dlPFC, and increased a post-response beta rebound in both regions. Importantly, we identified a pre-trial marker of proactive control where dmPFC theta power increased before trials when conflict was expected, and theta, beta, and HFA conflict signals in both regions were enhanced when conflict was rare and diminished when conflict was common. These findings reveal shared HFA but dissociable oscillatory dynamics in dmPFC and dlPFC during reactive conflict processing, highlight pre-trial dmPFC theta as a potential substrate for proactive control, and refine the roles of dmPFC and dlPFC in control adaptations.

neuroscience↗