Green-synthesized Titanium Dioxide Nanoparticles: Systematic Review of Antimicrobial Efficacy and Biocompatibility.

Abstract

Background: Green-synthesized TiO2 nanoparticles represent sustainable alternatives to conventional antimicrobials combining strong bioactivity with lower environmental impact.

Objective: This study evaluates their antimicrobial efficacy and cytotoxicity when produced via plant-mediated synthesis.

Methods: A search was conducted in the PubMed, Web of Science, Scopus and EMBASE databases, following the PRISMA guidelines, with no restrictions on publication date or language. Eleven studies pub-lished between 2018 and 2025 were included by two independent reviewers, with methodological quality assessed using the QUIN tool for in vitro studies.

Results: The nanoparticles exhibited predominantly spherical morphology and sizes ranging from 10 to 146nm, with pronounced broad-spectrum antimicrobial activity against Gram-positive bacteria (e.g., Staphy-lococcus aureus, Bacillus subtilis), Gram-negative bacteria (e.g., Escherichia coli, Pseudomonas aeruginosa), and fungal species (e.g., Candida albicans, Aspergillus niger), with particularly remarkable potency against Gram-positive strains, displaying minimum inhibitory concentration (MIC) values as low as 0.125 µg/mL Mechanistic investigations implicated photocatalytically generated reactive oxygen species (ROS) as the principal driver of antimicrobial action, mediating oxidative stress, membrane destabilization, and cellular damage. Importantly, cytotoxicity assays demonstrated minimal deleterious effects on mammalian cells, with >80% viability maintained in HUVECs even at concentrations up to 1000 µg/mL highlighting the favorable biocompatibility of these nanomaterials.

Conclusion: Nevertheless, heterogeneity in synthesis pro-tocols and the paucity of direct comparative studies with standard antibiotics underscore the necessity for methodologi-cal standardization. Collectively, these findings substantiate the potential of green-synthesized TiO₂ NPs as versatile can-didates for biomedical, agricultural, and environmental applications, while emphasizing the imperative for further opti-mization and translational validation.