Standard biological assays to estimate nanoparticle toxicity and biodistribution

Nanoparticles (NPs) have gathered considerable attention in recent years due to their unique physicochemical and optoelectronic properties and applications in various sectors of public health, medicine, environment, and agriculture, etc. Therefore, the safety assessment of NPs is one of the key concerns that must be explored before the actual applications of these NPs are realized. Broadly, the biocompatibility of NPs can be accomplished by several methods based on the experimental models, in vitro or in vivo. In vitro methods of evaluation of NP toxicity are easy to perform and provide fair information about the cytotoxicity or genotoxicity induced by NPs. Some common in vitro cytotoxicity assessing methods are, 3-(4, 5-dimethylthiazol-2-yl)-2-5-diphenyltetrazolium bromide, neutral red uptake, and lactate dehydrogenase, however, micronucleus formation, comet assay, and chromosomal aberration, etc are used for evaluating genotoxicity potential of NPs. In vivo bio-distribution of NPs can be determined by real time monitoring of NP accumulation in animals or by harvesting their organs or tissues followed by estimating the concentration of NPs. Computed tomography, magnetic resonance imaging, nuclear medicine imaging, and liquid scintillation counting techniques are some of the common methods currently being used for monitoring biodistribution of NPs in animals. Organ/tissue specific NP biodistribution and co-localization can be studied by histology imaging under light microscopy, fluorescence microscopy, and electron microscopy.