Table 1.

Layered hydroxide nanocomposite toxicity and bio-distribution studies

Nanocomposite type	Method of synthesis	Size (nm)	Concentration (μg/ml)	Assay (Test)	Cell type	Refrence	Remark
1. Mg–Al–LDH	Co-precipitation/ion exchange	50-100	40	MTT	Human kidney (N)	[4]	Contain folic acid and not toxic, more than 80% of cell viable after 3days.
2. Zn–Al–LDH	Co-precipitation	_	150	MTT	Mouse fibroblast (C)	[7]	Higher fibroblast viability with LDH-levodopa treatment than pure levodopa, LDH alone no significant effect on fibroblast
3. ZLH	Direct method	_	20	MTT	Human liver cell (HepG2) (C)	[8]	Hippuric acid (HA) intercalated ZLH showed better synergy than pure HA and tamoxefen on cancer cells.
4. Mg–Al–LDH	Co-precipitation	150-200	100	MTT	Colon cell(C)	[10]	LDH coated with chitosan also not toxic at this dose on this cells
5. Mg–Al–LDH	Ion exchange	>300		Animal single dose	Whole animal	[13]	Contain captopril and not toxic to the animal exposed.
6. Mg–Al–LDH	Co-precipitation	80-90	20	MTT	Human cervical cancer (C)	[16]	Potentiate the effect of paclitaxel
7. Mg–Al–LDH	Co-precipitation	129-149	100	MTT/Trypan blue	Cortical neuron(N)	[17]	DNA loaded LDH less toxic than pristine LDH at higher dose
8. Mg–Al–LDH	Co-precipitation	_	1000	MTT	Human osteosarcoma (C)	[18]	5-fluorouraci loaded LDH show better effect than free drugs
9. Mg–Al–LDH	Co-precipitation	50,100,200,350		MTT	Fibroblast(N) and lung(c)	[20]	Potentiate the effect of anti-cancer and milder on normal cells
10. Mg–Al–LDH/Zn-Al-LDH	Co-precipitation	_	80mg/kg of ketoprofen	Magnifying lens	Mucosal surface	[21]	Ketoprofen induced gastritis was reduced with LDH intercalation
11. Mg–Al–LDH	Co-precipitation	_	5-2000mg/kg	Blood chemistry	Balb/c mice	[26]	No significant changes to clinical and biochemical parameters and no evidence of particle retention in tissues.
12. Zn-Al-LDH	Co-precipitation/ion exchange	_	1.2	MTT	Chang liver cells (N)	[29]	Lower concentration used and no effect on viability from either the carrier or loaded LDH
13. ZLH	Direct method	_	1000	Trypan blue	Chang liver cells (N)	[30]	No Significant cell viability decrease below 125μg/ml with good anti histamine release from the intercalated cetirizine.
14. Zn-Al-LDH	Direct method	150	800	MTT, GSH, ROS, NO, comet assay,	Cervical cell (Hela) (C)	[32]	Only dose above 400ug/ml causes DNA damages, hence biocompatibility possible since it has no toxic effect at lower doses base these assays.
15. Zn–Al–LDH	Co-precipitation/ion exchange	_	50	MTT	Mouse fibroblast and human lung fibroblast cells	[33]	The toxic effect of Para-amino salicylic acid on the two cells was decrease after intercalation into this LDH
16. Mg–Al–LDH	Co-precipitation	50-300	2000	Trypan blue dye exclusion	Human Embryonic Kidney cell (HEK 293T) (N)	[34]	More than 50% of cells viable at 500μg/ml. DNA transfection successful but lower than using commercial means.
17. Mg–Al–LDH	Co-precipitation/ion exchange	57-63	40	MTT	Human gastric epithelial cell (GES-1) gastric cancer cell (MKN45 and SGC-7901)	[36]	Etoposide harmful effect on normal cell significantly reduced and its anticancer effect enhanced after intercalation into LDH.
18. Mg–Al–LDH	Co-precipitation	_	50	MTT	Breast (MCF-7) (C),cervical (HeLa) (C), and fibroblast (3T3) (N)	[37]	Not toxic to all the three cell line, but enhanced the anti-cancer effect of protocatechuic acid.
19. Mg–Al–LDH	Co-precipitation	20	50	MTT	lung fibroblast cell (N)	[38]	No toxic effect against the tested cells and bacteria. Activity of the intercalated antibiotics similar to the naked one

The table summarises some of the layered hydroxide nanocomposite activity in relation to toxicity and distribution over the last few years. The majority of whom were synthesis by either co-precipitation or ion exchange method, with sizes between 50-300 nm in most of them. Cell proliferation assay using MTT is applied in large no of the studies to evaluate for their cytotoxic and or anti-cancer impact on some selected cell lines.