Table 2.

Summary of the types of CDs and their toxicity and drug loading capacity.

Type	Size of CDs	Size of nanocarriers	Surface Engineering	Drug	DLC, (wt%)	Cell lines, Animal models	Observation	Ref
Qucbl-CDs	5-7 nm	60-80 nm	Covalently anchored	Qucbl	N/A	Hela	Qucbl-CDs: 0-50 μM, cellviability >90%	203
DOX-CDs	6.8±_1.3 (D) 8 (H)	N/A	Physisorbed through interactions such as π-π stacking, hydrophobic and van der Waals interactions	DOX	6.0	A549	DOX-CDs: 400 μg mL-1, no growth inhibition	204
CA-CD	N/A	220 ± 25.99 um	Hydrogen bonding	b-TC	77	N/A	N/A	205
CDs-Oxa	2.28±0.42 nm (D) 0.34-1.4 nm (H)	2.71 ± 0.43 nm (D) 2.5-4.2 nm (H)	Condensation reaction between the amino groups and the carboxyl group	Oxa(IV)-COOH	4.2	L929; HepG2	CDs: 0.5 mg mL-1, survival rates > 75%; CD-Oxa: cytotoxic as oxaliplatin(II) (IC50 = 3.4 µg mL-1)	206
CDs-Pt(IV)@PEG-(PAH/DMMA	7 nm	125 nm	Intriguing charge conversion to a cationic polymer	Pt(IV)	6.7	A2780	CDs: 3.125-400 μg mL-1, no toxicity (A2780); CDs-Pt(IV)@PEG-(PAH/SA): 0.18-11.44 μM, no toxicity to cancer cells at pH 6.8 or 7.4	207
CDsRGD-Pt(IV)-PEG	5-8 nm	31 nm	Intriguing charge conversion to a cationic polymer	Pt(IV)	4.1	MDA-MB-231, MCF-7 cells	CDs: 200 μg mL-1, negligible toxicity, CDs-RGD-Pt(IV)-PEG: at pH 6.8, much higher cytotoxicity	208
PNHCDs-DOX	5.8±0.1 nm (D) 3.8 nm (H)	N/A	Interactions such as electrostatic attraction, π-π stacking, van der Waals force, and hydrophobic interaction	DOX	35.43	HepG2, SiHa, MCF-7	PNHCDs: no affect to cell survival; PNHCDs-DOX: 400 μg mL-1, 65-70%	209
CD-DOX conjugates	2-6 nm	N/A	Amines bind with the carboxylic acid via electrostatic interactions or hydrogen bonding.	DOX	N/A	HepG2 cells HL-7702 cells	CD: 1.5625-100 mg mL-1, no influence; CD-DOX: dose-dependent death	210
P-CDs/HA-Dox	1.4-3.2 nm	15-30 nm	Electrostatic self-assembly	DOX	6.3	HeLa, NIH-3T3	PCDs/HA-Dox: 50 μg/mL, 90% of NIH-3T3 cells survive	198
IL-OCDs/Cur	7.2 nm	N/A	Hydrophobic interaction	Cur	69.2	HeLa cells.	IL-HCDs: 50 μg mL-1, cell viability of >80%,	211
DOX@ACD	119±207 nm	131 ± 3.7 nm	Amphiphilic interaction	DOX	14.2 ± 0.003 wt%	A549	ACD@DOX: higher cell viability at low concentrations and lower viability at higher than DOX.	212
FA-Gd@CQDs/DOX	4.0 ± 0.7 nm	N/A	π-π stacking and hydrophobic interactions.	DOX	74.5 ± 3.96	HeLa, HepG2, and HeLung cell	FA-Gd@CQDs: low cytotoxicity, FA-Gd@CQDs/DOX: greater cell growth inhibition toward HeLa cells than DOX	213
pCBMA(CD-D/DOX)	3 nm	183 ± 27 nm (D) 200 nm (H)	Electrostatic interactions and π-π stacking	DOX·HCl	96.9	4T1 and HepG2 cells	CDs: 0.01-5 μg/mL-1, survival rates ~100%; pCBMA(CD-D/DOX): at low DOX dose (0.01, 0.1 μg/mL), 4T1 cells incubation rates ~100%	214
CDs-epi	1.5 (D) 1.7(H)	2.6 (D) 3.5 (H)	Conjugated	Epirubicin	N/A	SJGBM2, CHLA200, CHLA266, U87	CDs-epi: 10 μM, 17-30% survival rates	215
p(CAT2-CD-BA1)	2.72 nm	3.79 nm	Noninvasive adsorption	DOX	84.28	HeLa	p(CAT2-CD-BA1): 100 μg mL-1, cell viability unchanged	216
CD-PEI-DOX	2-8 nm (D), 2-10 nm (H)	222.5 ± 20.1 nm	Electrostatic interactions	DOX	35.88	L02, MHCC-97L, Hep3B	CD-PEI-DOX: (<10 μg mL-1, effective inhibition, far less cytotoxic to L02 than to cancer cells	217
DS-NA	5 nm	7235 ± 2.9 nm	Hydrophobicity interaction	DOX	23.5	MDA-MB-435S, 4T1	DS-NA: higher cytotoxicity to MDA-MB-435S cells (IC50 = 4.841 μg mL-1) than 4T1 cells (IC50=16.08 μg mL-1)	218
APCDs@Fe/DOX-LOS	9.4±0.62 nm	106 ± 1.5 nm	π-π stacking interaction with large p-conjugated structure of APCDs	DOX	30.3 ± 1.3	4T1 tumorbearing mice	Blood biochemical parameters: levels remained normal ranges, H&E staining: no noticeable morphological damage or inflammatory injury	219

Abbreviations: D—diameter; H—height; DLC—Drug loading capability