Impact of pusher and puller bacterial suspensions on enhanced convective drug delivery into porous tissue

Modern medicine heavily relies on drug delivery systems to ensure targeted and effective administration of therapeutic agents. One such promising innovation is the development of self-propelled particles, inspired by motile cells like bacteria, for drug delivery purposes. These nano- and micro-motors have shown great potential in enhancing drug delivery effectiveness. Active fluids, containing self-propelled agents, have been shown to significantly improve transport properties by converting environmental or external energy into mechanical energy. Due to the aerotaxis and chemotaxis properties of bacteria, they are particularly useful in targeted drug delivery. In the present study, the impact of the band formation phenomenon on the probability of finding a particle with a specific orientation at a given time was investigated. This was achieved by coupling the equations describing bacterial density, Fokker–Planck, and Navier–Stokes. Furthermore, the comparison of drug distribution and penetration depth in porous tissue for bacterial suspensions containing pusher and puller bacteria was conducted by solving the mass transfer equation. The findings revealed that the presence of bacteria increases the penetration depth by a factor of 1.7 for the suspension containing puller bacteria, and 1.4 for the suspension containing pusher bacteria. The drug distribution in suspensions containing puller particles is more efficient due to the favorable flow direction. This study potentially has significant implications for targeted drug delivery and improving drug efficacy in porous tissues. The use of coupled complex equations provides a comprehensive approach to modeling the behavior of bacterial suspensions and their impact on drug distribution.