Interactions of nanoparticles with living and synthetic bio-membranes

Interactions between nanomaterials and biointerfaces are of great interest across many research fields, including chemistry, physics, engineering, and biology, with applications from diagnostics to therapeutics, and in drug delivery systems. By tailoring nanomaterial properties <i>via</i> functionalisation, their efficacy can be enhanced for a variety of biomedical scenarios. Nanomaterial-based therapeutics, diagnostics, and theranostics display a common need to interact with biological tissue, <i>i.e.</i>, they must make contact with, and often transverse, the external membrane of a cell or organism to elicit the desired response. As such, understanding nanoparticle (NP)-bio-membrane interactions is paramount to designing and optimising nanoparticle-based therapies and technologies for biological applications. Historically, <i>in vivo</i> investigations have proven to be challenging due to the complexity and intricate interactions involved with complete cell membranes. This has led researchers to employ model bio-membranes, which can be investigated using a range of <i>in vitro</i> experimental and theoretical techniques, to isolate the underpinning interaction mechanisms of NPs at the bio-interface. This review aims to unify the current literature regarding the biophysical interactions between inorganic and organic NPs and bio-membrane interfaces, including living and synthetic systems. The article will explore the role of membrane composition, NP morphology and chemistry, and the forces involved in interactions between the two entities. Identifying the fundamental influences of NP-membrane interactions, primarily synthetic NPs as these are more clinically applied, will allow for the more effective design of novel biomedical agents for future therapies.