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IntroductionHuman exposure to nanoparticles is increasing due to their widespread use in industry and consumer products. The unique physicochemical properties of these materials lead to novel toxicological effects, primarily driven by the induction of oxidative stress and inflammation, establishing nanotoxicology as a critical public health field. This scoping review synthesizes the current evidence from preclinical models to provide an overview of the mechanisms and end-organ toxicities associated with exposure to metal-containing nanoparticles.MethodsA scoping review was conducted following the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guidelines. The PubMed database was searched on August 11, 2024, using a detailed search string focused on nanoparticle inhalation, human toxicity, and metals. Inclusion criteria specified English-language articles reporting on in vivo or in vitro human tissue studies, while studies that were animal-only, reviews, or non-toxicological modeling were excluded.ResultsThe initial search yielded 946 records; ultimately, 136 articles were analyzed based on the inclusion and exclusion criteria. A thematic analysis of the included studies reveals that research is heavily concentrated on the respiratory, gastrointestinal, and immune systems, with titanium dioxide and zinc oxide being the most frequently investigated nanoparticles. Across all organ systems, the principal mechanisms of toxicity were consistently identified as the generation of reactive oxygen species and the initiation of inflammatory cascades. Key organ-specific findings include disruption of the respiratory epithelial barrier, nanoparticle translocation to the cardiovascular and nervous systems, associated mitochondrial damage and protein aggregation, and dose-dependent genotoxicity, including DNA strand breaks and micronuclei formation.DiscussionThe toxicity of metal-containing nanoparticles is highly dependent on their specific physicochemical characteristics, including size, chemical composition, and agglomeration state. While in vitro models have been invaluable for elucidating these mechanistic pathways, significant limitations remain, including a lack of standardization and challenges in translating findings to clinical outcomes in humans. Future research should focus on validating advanced, reproducible models, investigating complex mixed exposures, and identifying sensitive biomarkers to better inform risk assessment and protect public health.Clinical trial numberNot applicable.

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Titanium dioxide (TiO2) and Zinc Oxide (ZnO) are two wide-bandgap (Eg) materials (Eg ~3 to 3.3 eV) that have gained significant interest from researchers and are extensively studied in the field of optoelectronics due to their functionality in the UV region. In addition to having a bandgap corresponding to UV radiation, these metal oxides are also considered environmentally friendly, have a cost-effective synthesis and device fabrication mode, and are exhibiting strong physical and chemical stability against external environmental degradation. As observed, the bulk forms of TiO2 and ZnO operate in the UV region due to their favourable band gap. However, as they are downsized to the nanometre range, with varied sizes and morphologies, they can be tuned to work for a broader spectrum of wavelengths, i.e., in the UV-Vis region. Furthermore, in addition to nanostructured metal oxides, incorporating them as heterostructures can improve the overall working efficiency of fabricated devices. Reduced graphene oxide (rGO) is one such integrant that can be included in the heterostructure configuration, due to its stability and ability to boost efficiency owing to its tuneable low bandgap (Eg ~ 1 to 1.2 eV), dependent on its level of reduction, which aids in quicker charge transfer. The central research question that has been explored in this review is how the structural and morphological changes in TiO2, ZnO and rGO are influenced by the synthesis parameters, while also examining various fabrication techniques for constructing heterostructures and investigating how different heterostructure designs impact the UV-detection performance of TiO2, ZnO and ZnO or TiO2/rGO based photodetectors. In this review, we are presenting how the structural and morphological changes in TiO2, ZnO, and rGO affect the detection efficiency of photodetectors operating in the UV-Vis region, and how the heterostructures configured by these materials further influencing the performance.

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This systematic review assesses the necessity of in vivo models in determining whether these novel dual-biofunctional coating could induce osseointegration and exhibit antibacterial activity by providing a comprehensive biological response that in vitro models cannot replicate. This systematic review included in vivo studies involving intraoral implantation. A comprehensive search of original research published in English up to December 2024 was conducted across Medline, Scopus, and Web of Science. From the screened studies, 16 studies (1 clinical trial and 15 animal studies) met the inclusion criteria. The clinical trial involved 15 patients and reported 4-month outcomes. A large variance was observed among the protocol of animal studies, comprising five species (rats, rabbits, dogs, pigs, and goats). Six studies utilized peri-implantitis models to evaluate osseointegration outcomes under disease challenge. The reviewed studies highlighted various osseointegration-promoting components, such as inorganic compounds (e.g., calcium phosphate), peptides, and metal-based materials, as well as antimicrobial agents including metals, metal oxides, and polymers. By synthesizing in vivo findings, this review seeks to optimize dual-biofunctional coatings that simultaneously eradicate pathogenic bacteria and induce osseointegration within clinically relevant environments. Future work should aim to standardize in vivo protocols and new in vitro methods to reduce heterogeneity.

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