Inactivation of Bacterial and Viral Bioaerosols by Lactoferricin B-Coated Filters Under Various Environmental Conditions

Conventional antimicrobial air filters often conflate physical interception with true biochemical inactivation, posing secondary aerosolization risks during maintenance. This study developed a lactoferricin B-functionalized polypropylene (LfCF) filter to provide a dual-action mechanism: electrostatic capture and robust contact-killing against bioaerosols. To rigorously decouple these mechanisms, a polyallylamine binder-only (PP+PAA) control was incorporated. Dynamic penetration assays at 10 cm/s revealed that the 2.0 mg LfCF achieved significantly lower viable penetration rates for Escherichia coli (41.2%) and λ phage (46.0%) compared to the PP+PAA control (75.1% and 76.3%). This substantial gap demonstrates instantaneous sublethal injury upon aerodynamic impaction, defined here as “dynamic inactivation.” Crucially, time-dependent elution assays confirmed a >2 log reduction in viable counts for both retained E. coli and λ phage on LfCFs within 60 min, definitively validating its genuine contact-killing capability. Furthermore, the amphipathic lactoferricin B peptide maintained exceptional biocidal efficacy even under high-humidity conditions (70% RH), overcoming the electrostatic shielding typical of traditional biopolymers, without increasing aerodynamic pressure drop. Finally, field validation in a dental clinic demonstrated an 83.3% reduction in airborne viable bioaerosols. As a passive, self-sterilizing engineering control, the LfCF offers a highly reliable intervention for mitigating occupational bioaerosol exposures.