Physical properties of nanoparticles do matter

Abstract

Nanoparticles (NPs) have been used to enhance pharmaceutical properties of drugs, including cell/tissue penetration, selective biodistribution, circulation half-life, and accumulation at target sites. Rigorous efforts, including chemical modifications using target moieties, have been dedicated to improving their functions. Optimization of the physical properties of NPs, including size, shape, charge, and elasticity, is suggested to be an important step in the creation of NPs with desirable pharmacokinetic properties for use as drug delivery systems. In this review, we highlight recent findings on the effect of the physical properties of NPs, including the size, shape, surface charge, and elasticity on pharmaceutical functions. Many studies have demonstrated that 30–200 nm NPs facilitate cell uptake and do not trigger the immune response due to their relatively large surface area. Compared to spherical NPs, non-spherical NPs are not only advantageous for cell uptake but also for systemic circulation owing to their multivalent interactions with the cell surface. The slightly negative charges carried by NPs have been considered responsible for the reduced electrostatic interactions with plasma proteins. Importantly, soft NPs enhance cellular uptake, reduce immunogenicity, and enhance tumor accumulation compared to their hard counterparts. Nonetheless, it is not easy to offer unequivocal suggestions regarding the physical properties of NPs during their pharmacokinetic journey; this is due to the multifaceted aspects at each step. Smart NPs that can alter their physical properties by responding to environmental stimuli were developed as alternatives to address this issue. Thus, physical properties do play a very important role in determining the pharmaceutical applications of NPs.