Table 3.

In vivo and in vitro toxicological analysis of IONPs

Study Model	Size (nm) shape	Synthesis approach	Coating	Concentration	Cell line/in vivo model	Toxicity	Ref.
In vitro	50–150 Rod and spherical	Biological	Uncovered	200 µg/mL	Hepatocellular carcinoma (HepaRG) and Caco-2 cells	Caco-2 cells showed no changes in ROS, apoptosis, or mitochondrial membrane potential Two types of particles activated apoptosis in HepaRG cells, and one changed the mitochondrial membrane potential at non-cytotoxic doses	[24]
	45 Rod	Chemical	Βcd	40 µg/mL	Fibroblast cell line (NIH 3T3)	Over 24 h, Prussian blue staining indicated complete uptake of IONPs βCD-IONPs had minimal toxicity in the NIH 3T3 cell line Dose-dependent cytotoxicity of bare IONPs	[110]
	20 Spherical	Chemical	PVP	1–100 μg/mL	Human neuroblastoma, SHSY5Y cell line	The mitochondrion was the first organelle affected at the cellular level in these human neuronal cells, after only 48 h The cellular membrane of SH-SY5Y cells was not degraded	[26]
	10	Chemical	Polyethyleneimine-interfering RNA	10–80 μg/mL	HSC-T6 cell lines	Very low toxicity to HSC-T6 cell proliferation was observed	[25]
	7–22 Polygonal	Biological	Oleic acid	5, 10, 25 µg/mL	Human keratinocytes HaCaT cells	Absence of toxicity to human keratinocyte viability, proliferation, and migration	[44]
	4	Chemical	Tartrate-adipate	0–4000 µmol/L	HT-29/Caco-2 cells	In vivo investigations in the small intestine revealed a 79.3% absorption rate	[29]
	5–10 Agglomerates	Chemical	Dextran	10–100 μg /mL	Human monocytes	No cytotoxicity detected Human monocyte viability was improved; however, the underlying mechanism remains unclear	[99]
	50 Globular	Biological	Natural amino acids	49–373 μg/mL	HFF2 cell line	Nontoxic and biocompatible These nanoparticles have potential uses in cellular labeling, drug and diagnostic delivery, and other biomedical applications	[65]
In vivo	6.2 ± 1.1 8.5 ± 1.6 Spherical	Chemical	Dextran Uncoated	0.1–100 μg/mL	Zebrafish (Danio rerio)	Uncoated IONPs at doses of 5 and 50 g/mL were very toxic to zebrafish embryos, causing death. Locomotor behavior appeared to be unaffected by uncoated IONPs Zebrafish larvae with damaged locomotor activity better absorb lower doses of dextran IONPs (1 g/mL)	[107]
	10	Chemical	SPION-PEI/siRNA	3 mg Fe/kg	Sprague Dawley Rats	SPION-PEI/siRNA complexes were particularly abundant in the liver and spleen, whereas iron was almost absent in the heart, lungs, and kidneys	[25]
	7–22 Polygonal	Biological	Oleic acid	300 µL	Hairless mice SKH-1	Acute dermal toxicity study outcomes revealed some alterations in physiological skin parameters, albeit at levels that were not sufficient to compromise the skin barrier function	[44]
	100 50 30	Chemical	Phospholipid Dextran Uncoated	6 mg/day	Piglets (males)	No signs of iron toxicity for a variety of toxicological indicators that could suggest the occurrence of oxidative stress or inflammation Promising nutritional iron supplement	[10]
	45 Rod	Chemical	β-cyclodextrin	2000 mg/kg	Wistar rats	No significant cellular toxicity was observed after 14 days of exposure	[110]
	4	Chemical	Tartrate-adipate	35.6 ± 0.6 mg/kg	Wistar rats	The duodenum plays an essential role in iron absorption, with up to 38% and 62% greater iron intake in this region than in the jejunum and ileum, respectively Low cytotoxicity and ROS generation were identified, indicating only minor increases in free radical production The bloodstream appears to play a role in the systemic biodistribution of IONPs to organs such as the spleen, liver, and kidneys	[29]

ROS reactive oxygen species, IONPs iron oxide nanoparticles, βCD β-cyclodextrin, SPION-PEI/siRNA Polyethyleneimine designed for small interfering RNAs