Decoupling Airflow Reveals a Charge-Dose Operating Window for Collector-Side Bioinactivation at MnO x /FTO Electrostatic Interfaces

The biological fate of species deposited on electrostatic collectors remains difficult to resolve because airflow, discharge behavior, and interfacial processes are strongly coupled in practical systems. Here, we establish a zero-flow in situ discharge model to isolate collector-side responses at MnOx/FTO and bare FTO interfaces. Under identical electrode geometry, MnOx/FTO exhibited a stronger electrical response than bare FTO, while matched 6 kV exposure experiments produced greater biological damage on MnOx/FTO at the same exposure durations. This disparity demonstrates that nominal voltage and time do not necessarily represent equivalent interfacial electrical exposure. We therefore integrated the measured nonsteady current of MnOx/FTO to define the cumulative interfacial charge dose, Q, as a condition-specific descriptor of the accumulated electrical input. Increasing Q was associated with progressively stronger membrane damage and apoptosis-associated signaling, progressing from clear biological perturbation at Q1 to more pronounced responses at Q2 and further amplification at Q3. Electrostatic simulations indicated collector-side field localization, while ex situ XPS revealed non-monotonic Mn/O surface-state reconstruction, with defect-related oxygen reaching a maximum at Q2. Together, these results establish a charge-defined framework linking material-dependent discharge behavior, interfacial evolution, and collector-side biological response.