Nanoscale anisotropy for biomedical applications

Nanoparticles exhibit anisotropy when distinct features can be identified along different axes. Such disruption in shape and/or composition symmetry can change how nanoparticles behave and interact with the surrounding environment compared with their isotropic counterparts. Anisotropic combinations can be limitless and show potential for tackling biological barriers and developing programmable, targeted, and combined delivery of bioactive molecules, mainly when featuring autonomous motion. In this Review, we summarize the main methods for the generation of anisotropic particles at the nanoscale. We further discuss how geometric cues or the incorporation of propulsive agents (chemically or physically driven) improve transport across biological fluids, promote cellular adhesion and internalization, and/or increase tissue penetration. We finally highlight considerations for the design of anisotropic nanoparticles and the precise control over morphology and properties, in addition to the challenges for clinical translation. Using nanoparticles featuring anisotropic characteristics is a promising approach to developing multifunctional platforms for drug delivery and theranostics. This Review discusses methods to generate anisotropy in nanosystems and strategies to control particle transport, targeting and interaction with cells to overcome biological barriers.