**6. Conclusion**

Throughout the years, the remarkable properties of NPs have led to their recognition as marvels of contemporary science because of their extensive applications. The employment of NPs in the biomedical field has contributed significantly to overcoming numerous diseases and improving the quality of human life. Unlike other delivery methods, orally administering NPs exposes them to various biological and chemical conditions, such as enzyme and microbiota-related digestion and fluctuations in ionic strength and pH levels. Nanotoxicity generally stems from the instability of the NPs and distinct physicochemical properties. Numerous factors, such as the type of NPs, particle and pore size, the extent of modification, frequency and amount of dosage, and administration timing, influence them. Other crucial factors include cell type, cell condition, organ distribution, animal condition, and delivery duration, presenting individual differences in cellular and *in vivo* contexts. NPs toxicity

mechanisms include oxidative stress, inflammation, and apoptosis; however, studies of the implicated signal pathways are still relatively scarce. Due to the numerous variables involved, there currently needs to be a standardised approach to toxicity research. Investigations of NPs toxicity should consider their actual applications and refine safety evaluation indicators for both in vitro and in vivo testing. As observed, a limited amount of data is available for specific NPs types used in DDS. Consequently, before introducing NPs into the therapeutic market, it is essential to evaluate the risk-benefit ratio.
