. 2019 Dec 23;13(1):96. doi: 10.3390/ma13010096

Table 1.

Various GQD-loaded immunosensing platforms reported (2016 onwards) for cancer diagnosis.

Electrode	Nanomaterials	Biomarker	Assay Type	Technique(s)	Sample(s)	Linear Range	LOD	Reference
Pt-electrode	N,S–GQDs/Au–PANI	CEA	Direct	EIS	Human serum	0.5–1000 ng mL⁻¹	0.01 ng mL⁻¹	[122]
GCE	PtPd/N–GQDs/Au	CEA	Direct	Amperometry	Human serum	5 fg mL⁻¹–50 ng mL⁻¹	2 fg mL⁻¹	[67]
GCE	P5FIn/erGO/GQDs/Au	CEA	Sandwich	ECL	Human serum	0.1–10 ng mL⁻¹	3.78 fg mL⁻¹	[123]
SPCE	MWCNTs/GQDs	IL-13Rα2	Sandwich	Amperometry	Raw cellular lysates from human CRC	2.7–100 ng mL⁻¹	0.8 ng mL⁻¹	[124]
SPdCE	MWCNTs/GQDs	IL-13Rα2, CDH-17	Sandwich	Amperometry	Raw cellular lysates from human CRC and breast cancer	4.92–100 ng mL⁻¹ (IL-13sRα2) 0.11–10 ng mL⁻¹ (CDH-17)	1.44 ng mL⁻¹ (IL-13sRα2) 0.03 ng mL⁻¹ (CDH-17)	[112]
SPCE	N,S–GQDs/AuNPs	HCG	Direct	CV, SWV, EIS	Human serum	0.1–125 pg mL⁻¹	12.5 fg mL⁻¹	[61]
Au-electrode	P-Cys/GQDs/AuNPs	p53	Direct	SWV, DPV	Human plasma	0.0488–12.5 pM	23.4 fM	[125]
GCE	CysA/AuNPs/GQDs	CA 15-3	Direct	SWV, CV	Human plasma; cellular lysates from human breast cancer	0.16–125 U mL⁻¹	0.11 U mL⁻¹	[126]
GCE	Au/Ag–rGO/GQDs	PSA	Direct	EIS, ECL	Human serum	1 pg–10 ng mL⁻¹	0.29 pg mL⁻¹	[127]
GCE	GQD/GS	PSA	Sandwich	SWV	Human serum	0.005–10 ng mL⁻¹	3 pg mL⁻¹	[128]
GCE	GN–Ag–Au/GQDs	CA 199	Sandwich	ECL	Human serum	0.002–70 U mL⁻¹	0.96 mU mL⁻¹	[129]

Abbreviations: Ag: Silver; AuNPs: Gold nanoparticles; CA 15-3: Carcinoma antigen 15-3; CA 199: Carbohydrate antigen 199; CEA: Carcinoembryogenic antigen; CDH-17: Cadherin-17; CRC: Colorectal cancer; CV: Cyclic voltammetry; CysA: Cysteamine; DPV: Differential pulse voltammetry; ECL: Electrochemiluminescence; EIS: Electron impedance spectroscopy; erGO: Electrochemically reduced graphene oxide; GCE: Glassy carbon electrode; GN: Graphene; GS: Graphene sheets; GQDs: Graphene quantum dots; HCG: Human chorionic gonadotropin; IL-13Rα2: Interleukin-13 receptor α2; MWCNTs: Multi-walled carbon nanotubes; N,S–GQDs: Nitrogen- and thiol-doped graphene quantum dots; p53: Tumor protein-53; P5FIn: Poly(5-formylindole); PANI: Polyaniline; P-Cys: Poly L-cysteine; Pd: Palladium; PSA: Prostate-specific antigen; Pt: Platinum; r-GO: Reduced graphene oxide; SPCE: Screen-printed carbon electrode; SPdCE: Screen-printed dual carbon electrode; SWV: Square wave voltammetry.