Cellular interactions of therapeutically delivered nanoparticles.

INTRODUCTION: Nanoparticles (NPs) are used extensively in drug delivery. They are administered through various routes in the host, and their uptake by the cellular environment has been observed in several pathways. After uptake, NPs interact with cells to different extents, depending on their size, shape, surface properties, ligands tagged to the surface and tumor architecture. Complete understanding of such cellular uptake mechanisms and interactions of NPs is important for their effective use in drug delivery. AREAS COVERED: This article describes the various cellular pathways for NP uptake, and the factors affecting NP uptake and interactions with cells. Understanding these two important aspects will help in the future design of NPs for effective and targeted drug delivery. EXPERT OPINION: Surface charge and ligands tagged on the surface of NPs play a critical role in their uptake and interaction with cells; so surface modifications of NPs can offer increased drug delivery effectiveness, for example, the coupling of ligands on the surface of NPs can increase cellular binding, and NPs in biological fluids can be coated with proteins and as such can exert biological effects. All of the factors affecting NP uptake need to be investigated thoroughly before interpreting any NP-cellular interactions.