Nanotoxicity induced by nanomaterials: A review of factors affecting nanotoxicity and possible adaptations

Owing to their unique characteristic features (e.g., nano-scaled dimensions, surface charge, surface chemistry, thermodynamics, morphology, etc.), diversity of functionalization, and great penetrability to body tissues, nanomaterials have been widely employed in various fields including medical and health sciences. The feasibility and significance of nanomaterials has been well-explored as drug delivery devices, diagnostic tools, vaccination, prognostic agents, and gene therapy; however, substantial evidence on safety of these nanomaterials is lacking. The aim of this study was critical evaluation of available literature on the safety concerns of various nanomaterials and conceptualization of vital factors which might help in mitigating the toxicity caused by these nanomaterials. It has been established that various factors such as particle size, dosage regimen, route of exposure, surface chemistry, degree of aggregation, transmembrane diffusivity, excretion pathway, and immunogenicity play key role in inducing the nanotoxicity. By controlling these factors, interaction of nanomaterials with biological tissues, their penetrability, diffusivity, absorption, distribution, recognition by the immune players, duration of deposition into various body tissues, and clearance from the body can be controlled to avert unintended nanotoxicity. Furthermore, it has been identified that surface functionalization of nanomaterials with diverse moieties such as sodium citrate, polyvinylpyrrolidone (PVP) and/or surfactants could significantly downregulate their nanotoxicity potential and improve their safety profile. Factually, nanotoxicity is a grave concern which should be consider while designing of any nanomaterials to circumvent their detrimental interactions with various biological tissues.