A review of imperative concerns against clinical translation of nanomaterials: Unwanted biological interactions of nanomaterials cause serious nanotoxicity

Owing to their specialized characteristic features, nanomaterials have been dynamically employed in various fields including the medical and health sciences. However, unwanted biological interactions of nanomaterials with biomolecules, cells, tissues, organs, or body systems is critically important and not fully understood, yet. Therefore, the aim of the present review is to critically analyse the available evidence and comprehend the journey of nanomaterials in the body after their exposure through different routes (i.e., oral, inhalation, percutaneous or intravenous). Analysis of the literature revealed that upon interaction with biological tissues, nanomaterials induce oxidative stress via generation of super-reactive free radical species, leading to genotoxicity, mitochondrial damage, lysosomal dysfunction, and ultimately cell necrosis or apoptosis. The nanotoxicity induced by nanomaterials is very much dependent on their physicochemical features (i.e., size, surface chemistry, and morphology), dosage regimen, route of exposure, and immunogenicity. Through careful design of nanomaterials exhibiting optimum physicochemical characteristics and successive assessment of nanotoxicity through validated experimentation, unwanted biological concerns can be avoided.