Table 6.

Graphene biosensors for the detection of health-indicating analytes in saliva

Biomarker	Sensing Platform	Detection Method	LODa	Detection Range	Recoveryb	Validation	Assay Time	Sample Volume	Preparation	Reference
Cardiac troponin (cTnI)	N-prGO-(py-PEG/Py-COOH=20:1)/GCE	DPV	1 pg mL−1	0.001 – 100 ng mL−1	N/A	ELFA	N/A	N/A	Whole saliva	(Chekin et al. 2018b)
Cortisol	GNPs and PS67-b-PAA27 on Whatman filter paper	EIS	1 pg mL−1	1 pg mL−1 – 10 ng mL−1	N/A	ELISA RE62011 kit R2 = 0.9386	10 min	20 μL	1:10 dilution	(Khan et al. 2017a)
Cortisol	GNPs and PS67-b-PAA27 on Whatman filter paper	Chemi-resistive	3 pg mL−1c	0.018 – 4.552 ng mL−1c 3 pg mL−1 – 10 μg mL−1d	N/A	ELISA RE62011 kit R2 = 0.9951	12 min	5 μL	Whole saliva	(Khan et al. 2017b)
Cortisol	c-Mab conjugated rGO sheet/ITO/glass	Chemi-resistive	10 pg mL−1 (27.6 pM)	1 – 10 ng mL−1	N/A	ELISA	N/A	N/A	1:1 dilution with buffer solution	(Kim et al. 2017c)
Cortisol	anti-cortisol antibody/d-BSA/rGO/quartz	EIS	10 pM	10 pM – 100 nM	92 – 103%	N/A	30 min	1 mL	Whole saliva	(Kim et al. 2017b)
Cortisol	BSA/anti-Cab/SAM/CBμE/PS_b_PAA/G RP/Paper	EIS	0.87 pg mL−1	1 pg mL−1 – 10 ng mL−1	91 – 113%	ELISA 96.3% accuracy	12 min	5 μL	Whole saliva	(Khan et al. 2019)
Ghrelin (GHRL)	anti-GHRL-Phe-rGO/SPCE	DPV	1 pg mL−1e	10−3 – 100 ng/mL	97%	ELISA LOD = 161 pg/mL	N/A	3 μL	N/A	(Martínez-García et al. 2016)
Glucose	CuO/rGO/CNF/GCE	Chronoamperometric	0.1 μM	1 μM – 5.3 mM	99.7 – 101.3%	N/A	3 s	N/A	1:10 dilution	(Ye et al. 2013)
L-tryptophan (Try)	AuNPs/rGO/SPE	DPV	0.39 μmol/L	0.5 – 500 μmol/L	94.6 – 107.6%	N/A	N/A	N/A	Whole saliva	(Nazarpour et al. 2020)
Myoglobin (Mb)	anti-Mb-Ab/d-BSA/r-HGO/quartz	EIS	2.37 pM	5 pM – 10 nM	90.9–111.3%	N/A	N/A	N/A	Whole saliva	(Yoo et al. 2020)
Nitrite (NIT)	3D printed polylactic acid containing graphene (G-PLA) electrodes	DPV BIA-MPA	BIA-MPA: 0.03 μmol/L DPV: 30 μmol/L	BIA-MPA: 0.5–250 μmol/L DPV: 50–1300 μmol/L	100 – 110%	N/A	N/A	N/A	Dilution	(Cardoso et al. 2020)
Peptide YY (PYY)	anti-PYY-Phe-rGO/SPCE	DPV	0.02 pg/mLe	10−4 – 10 ng/mL	99%	ELISA LOD = 2.84 pg/mL	N/A	3 μL	N/A	(Martínez-García et al. 2016)
Serotonin	GO-chitosan modified GSPE	DPV	3.2 Nm	0.01 – 100 μM	104.20%	N/A	20 min	10 μL	N/A	(Adumiträchioaie et al. 2019)
Uric acid (UA)	3D printed polylactic acid containing graphene (G-PLA) electrodes	DPV BIA-MPA	BIA-MPA: 0.02 μmol/L DPV: 0.5 μmol/L	BIA-MPA: 0.5–250 μmol/L DPV: 10–70 μmol/L	120%	N/A	N/A	N/A	Dilution	(Cardoso et al. 2020)

^aS/N = 3, otherwise differently specified

^bvalues obtained in real saliva samples, otherwise differently specified

^cin saliva

^din buffer

^eS/N = 2