Summary of in vitro and in vivo studies testing the effects of pure and surface-modified CuO NPs^a.

Surface mod.	Size (in nm)	Main finding	VT	VV	Model systems	Dose/concentration	Cellular/tumoral effects	CCS	Mechanism	Ref.
Pure	7C, 127HD	CuO NPs inhibit pancreatic tumor growth primarily by targeting TICs via ROS and mitochondrial pathway	●	●	PANC1	VT: 0–50 μg mL−1; VV: 0–12.5 mg kg−1	Dose- and time-dependent ↓ cell viability. Tumor growth inhibition	●	↑ ROS, ↓ MMP, apoptosis of TICs (arrest in sub G1 phase)	149
Pure	22C, 167HD	CuO NPs induce mitochondria-mediated apoptosis in human hepatocarcinoma cells	●		HepG2	0–50 μg mL−1	Dose-dependent ↓ cell viability		Oxidative stress (↑ MDA, ↓ GSH) ↑ ROS, DNA damage. Mitochondria-mediated apoptosis (↓ MMP, ↑ P53, ↑ BAX/BCL2 and caspase-3)	150
Pure	20C	CuO NPs induce cytotoxicity via mitochondrial pathway	●		K562, PBMC	0–25 mg mL−1	Dose-dependent ↓ cell viability	●	↑ ROS, mitochondria-mediated pathway, ↑ P53 and Bax/Bcl2	151
Pure	30C, 235HD	Autophagy is the main mechanism of CuO NP-induced cell death, while apoptosis is only triggered secondarily	●		MCF7	0–12 μg mL−1	Dose- and time-dependent ↓ cell viability		Autophagy: ↑ MAP-LC3-II, Beclin1 and ATG5. 3 MA inhibits autophagy, and further Beclin1 KD leads to apoptosis (↑ PARP-cleavage, BAD dephosphorylation and caspase-3)	95
Pure	12C	CuO NPs synthesized from Eucalyptus globulus induce apoptosis in breast carcinoma	●		MCF7	0–100 μg mL−1	Dose-dependent ↓ cell viability		Impaired MMP, ↑ ROS, ↑ p53, bax, caspase-3, and caspase-9, cell cycle arrest in G1, S and G2/M phases	90
Fe-doped (0–10%)	11.8C–10.7C (0–10%)	6% Fe-doped CuO NPs induce inhibition of tumor growth and complete tumor remission when combined with immunotherapy	●	●	VT: MSC, Beas-2B, HeLa, KLN205; VV: KLN205	VT: 0–35 μg mL; VV: 0–225 μg kg−1 bw (6%)	↓ toxicity with ↑ Fe doping. ↓ tumor growth (6%-doped)	●	↑ membrane damage, ROS, autophagy. ↓ toxicity with ↑ Fe doping. VV: ↑ local antitumor immune response (activation of CD8+ and NK cells). Complete tumor remission due to treatment with 6%-doped NPs and EPAC	79
Fe-doped (10%)	235HD, 247HD (0, 10%)	Fe-doping of CuO NPs lowers their toxic potential on glioblastoma cells by slowing down Cu release	●		C6	0–1000 μM	Dose- and time-dependent ↓ cell viability. ↓ toxicity with ↑ Fe doping		↑ ROS and oxidative stress. Cu chelators can prevent Cu-induced toxicity	168
Zn-doped	30C	Zn–CuO NPs exert selective antitumor activity (inhibition of glioblastoma growth) and reverse temozolomide resistance in glioblastoma by inhibiting AKT and ERK1/2	●	●	VT: Panc28, HCT116, U87, C6, HELA, BeL7402, U251, A172, HUVEC, NIH3T3; VV: U87	VT: 5.0–20.0 μg mL−1; VV: 0–100 mg kg−1	Dose-dependent ↓ GBM cell proliferation. ↓ tumor growth, cell migration and invasion	●	↑ ROS, apoptosis (↑ procaspase-9, procaspase-3 and ↓ bcl-2/bax ratio), inhibition of AKT and ERK1/2	169
Zn-doped	30C	Zn–CuO NPs inhibit pancreatic cancer growth by inducing autophagy through AMPK/mTOR pathway	●	●	VT: AsPC1, MIA Paca2, HepG2, BxPC3, PANC1, HT29; VV: AsPC1	VT: 0–160 μg mL−1; VV: 5 and 10 mg kg−1	Dose-dependent ↓ cell viability. Inhibition of tumor growth		↑ ROS. Autophagy induced via AMPK/mTOR pathway (↑ p-AMPK, p-ULK1, Beclin-1 and LC3-II/LC3-I ratio, ↓ mTOR phosphorylation)	170
Zn-doped	2–10C	Zn–CuO NPs inhibit tumor growth by NF-κB pathway. NAC restores the balance disrupted by autophagy and apoptosis	●	●	VT: HepG2, Panc28; VV: Panc28	VT: 0–40 μg mL−1; VV: 5 and 10 mg kg−1	Dose-dependent ↑ cell proliferation inhibitory rates		NF-κB signaling involved in ROS-induced apoptosis (↑ Bax and caspase 3, Bcl-2 ↓) and autophagy (↑ LC3B and LC3 B/A). DNA, ER & Golgi damage. All effects restored with NAC	172
Zn-doped	3C	Zn–CuO NPs inhibit human CC growth through ROS-mediated NFκB activations	●		HepG2, Bel7402, A549, Panc28, HT1080, Hela, HUVEC, L02	0–60 μg mL−1	Dose-dependent ↑ cell proliferation inhibitory rates	●	↑ ROS and NF-κB pathway activation (↑ p-IKKα/β and nucleus p-NF-κB p65, ↓ IKKα, IKKβ, IκBα and nucleus NF-κB p65 expression). Induction of G2/M cell cycle arrest	171
Carbon (C)-coated	10.4–19.4C (CuO–C/Cu)	C-coat decreases cytotoxicity of CuO NPs due to reduced solubility, and CuO NPs induce greater toxicity than Cu2+	●		CHO, HeLa	30 ppm C/Cu, 34 ppm CuO	Dose-dependent ↓ cell viability. ↓ toxicity with C-coating	●		103
Protein coating (DMSA)	141HD (pure), 167HD (coated)	pCuO-NP-induce cell death in glioblastoma cells to a lesser extent than pure CuO NPs, due to reduced Cu ion release	●		C6, primary astrocytes	0–1000 μM	Dose- and time-dependent ↓ cell viability. ↓ toxicity with protein coat		↓ LDH and ↓ MTT reduction capacity. Cu chelators and low temperature ↓ toxicity	173

^{a C}core size, ^HDhydrodynamic size, VT in vitro, VV in vivo, CCS cancer-cell specific.