Relationship between bio-effects and energy transduction during nanoparticle-mediated photoporation

When a system comprised of cells, carbon black nanoparticles, and delivery molecules is irradiated with a laser beam, the nanoparticles can absorb and dissipate the laser-delivered energy, producing thermal and acoustic output and fluid mechanical forces. These can then interact with the nearby cell membrane, forming membrane pores that exogenous molecules can diffuse through and access the cytosol. This process, “nanoparticle-mediated photoporation,” can cause bio-effects like intracellular delivery of molecules and, at more extreme conditions, loss of cell viability. Through this work, we found that carbon black and carbon nanotubes generated greater bio-effects compared to graphite, diamond, or non-carbon materials, probably due to their more efficient laser energy absorption. Examining the dependence of bio-effects on energy absorption parameters like total energy absorbed, energy absorbed per nanoparticle, and energy absorbed per nanoparticle mass produced poor correlations. However, the correlation of bio-effects was much better with energy transduction parameters more closely related to the energy form transferred to cells like peak temperature, size, and number of vapor bubbles generated by the nanoparticles heated by the laser. A power-law relationship involving these three parameters indicated that peak nanoparticle temperature was the strongest determinant of bio-effects followed by bubble number and radius. This study provides a better understanding of the roles of energy absorption and transduction parameters on bio-effects during nanoparticle-mediated photoporation and facilitates the design of photoporation parameters that achieve desired bio-effects.