AAFQDs synthesized are compared based on the strategy used for functionalization, average size, and applications.

Amino acid	CD/CQD/GQD/GOQD	Synthesis/functionalization method	Average size	Ref.
l-Alanine	GQD	Two-step (modified Hummers method/amidation)	∼4.5 nm	72
β-Alanine	GOQD	Two-step (modified Hummers method/acyl chlorination & reflux)	1–11 nm	60
Arginine	GQD	One-step (hydrothermal)	5.5 nm	87
l-Arginine	GQD	Electropolymerization	—	88
Asparagine	GQD	Two-step (modified Hummers' method/Amidation)	4.1 nm	72
Aspartic acid	GQD	Electrodeposition	—	89
l-Aspartic acid	GQD	One-step (hydrothermal method)	4–9 nm	90
Cysteine	GQD	Two-step (hydrothermal/Surface condensation)	3.8 nm	75
	GQD	Two-step (pyrolysis/Amidation)	2.9 nm	77
l-Cysteine	CQD	Two-step (pyrolysis/Amidation)	7–10 nm	76
Glutamic acid	GQD	One-step (pyrolysis)	102.5 nm	91
	GQD	One-step (hydrolysis)	4.5 nm	92
Glycine	GQD	One-step (green pyrolysis)	3–5 nm	79
	GQD	Two-step (modified Hummers' method/amidation)	5.3 nm	72
	GQD	Two-step (pyrolysis/carbamate reaction)	5.9 nm	33
	CQD	One-step (pyrolysis)	5–10 nm	78
Histidine	GQD	One-step (thermal pyrolysis)	3.2 nm	98
	GQD	One-step (pyrolysis)	5–16 μm	99
	GQD	One-step (microwave)	200 nm	100
	GQD	One-step (pyrolysis)	3.7 ± 0.18 nm	53
	GQD	One-step (pyrolysis)	5.2 nm	94
	GQD	One-step (pyrolysis)	50 nm	101
	GQD	One-step (pyrolysis)	2.7 nm	97
	GQD	One-step (hydrothermal)	3.6 nm	96
l-Isoleucine	CD	Two-steps (thermal oxidation/surface condensation (amidation))	3–5 nm	52
l-Lysine	CQD	One-step (carbonization)	<10 nm	4
	GQD	Two-step (modified Hummers' method/surface condensation)	—	85
Phenylalanine	GQD	One-step (pyrolysis)	3.1 nm	95
Proline	GQD	One-step (pyrolysis)	22 nm	93
Tryptophan	GQD	Two-step (oxidation/cross-linking amidation)	20–30 nm	46
	GQD	One-step (pyrolysis)	2–10 nm	83
	GQD	One-step (hydrothermal)	2.7 nm	86
l-Tryptophan	CQD	Two-step (hydrothermal/direct surface condensation reaction)	5 nm	81
	GQD	One-step (thermal cracking)	7 nm	84
l-Tyrosine	CD	One-step (hydrothermal)	3–5 nm	80
Valine	GQD	One-step (pyrolysis)	3 nm	34