Plasmonic carriers responsive to pulsed laser irradiation: a review of mechanisms, design, and applications

Abstract

The ability to deliver molecules in an on-demand fashion with high spatial and temporal control represents an important challenge which could positively impact a wide range of biological applications. One such approach is through the development of “smart carriers” which release their cargo in response to an internal or external trigger. Light has been studied extensively as a stimulus as it can be applied externally to a system, can be optimized for biocompatibility, and controlled in both time and space. However, there are drastic differences depending on whether the irradiation source is a continuous wave or pulsed laser. While continuous wave light-responsive carriers have been more extensively studied, the use of pulsed lasers for system activation holds many significant benefits, such as the ability to achieve sub-second release while decreasing environmental heating and thus, increasing the promise of achieving high spatiotemporal resolution over cargo release. Pulsed lasers become increasingly useful when paired with plasmonic nanoparticles as photosensitizers, as their interactions can be controlled through a wide range of laser and nanoparticle parameters, and thus provides an avenue to create a highly tunable carrier system. This review will focus on hollow carrier systems, specifically, liposomes, polymersomes, and nanodroplets, which are photosensitized by plasmonic nanoparticles and demonstrate a response to pulsed laser irradiation. To fully realize the complexity of the factors which govern release, the systems will be discussed from various perspectives, including laser-nanoparticle interactions, mechanisms leading to membrane disruption, and their considerations in carrier design. Finally, we will present recent examples which have been implemented into biological systems.