Antimicrobial properties and biomedical potential of zinc oxide nanoparticles in pediatric diarrhea: A narrative review

• This manuscript presents a narrative review of the rule of ZnO-NPs in diarrhea treatment. • We identify critical gaps in the existing literature, particularly in this topic, that require further exploration. • A novel framework is proposed to enhance understanding and guide future research directions in the field. • Our findings emphasize the importance of using ZnO-NPs in diarrhea treatments. Zinc oxide nanoparticles (ZnO NPs) have been extensively investigated for their antimicrobial activity and potential relevance to pediatric diarrhea, owing to their size-dependent reactivity and ability to generate reactive oxygen species. This review critically examines recent experimental and preclinical studies reporting the antimicrobial effects of ZnO NPs, with particle sizes typically ranging from 10 to 80 nm and effective concentrations between 5 and 200 µg/mL. In vitro studies commonly report bacterial growth inhibition rates of 60–95% against enteric pathogens such as Escherichia coli and Salmonella spp., with smaller particles and surface-modified ZnO NPs showing enhanced activity compared to bulk ZnO and soluble zinc salts. Comparative analysis indicates that ZnO NPs often achieve similar or improved antimicrobial efficacy at lower zinc doses, while also exhibiting variable cytotoxicity depending on particle size, surface chemistry, and exposure duration. However, reported toxicity thresholds overlap with antimicrobial dose ranges, highlighting a narrow therapeutic window. The review further discusses mechanistic insights, including membrane disruption, oxidative stress induction, and ion release, as well as current limitations related to reproducibility, safety assessment, and lack of standardized dosing frameworks. Overall, while ZnO NPs demonstrate promising preclinical antimicrobial performance, their therapeutic applicability in pediatric diarrhea remains contingent upon rigorous in vivo validation and standardized safety evaluation.