Table 4.

Graphene biosensors for the detection of cancer markers in saliva

Biomarker	Sensing Platform	Detection Method	LODa	Detection Range	Recoveryb	Validation	Assay Time	Sample Volume	Preparation	Reference
CYFRA-21–1	BSA/anti-CYFRA-21–1/APTES/ZrO2-rGO/ITO/glass	DPV	0.122 ng mL−1	2 – 22 ng mL−1	N/A	ELISA RSD: 0.2– 3.35%	16 min	N/A	Whole saliva	(Kumar et al. 2016)
CYFRA-21–1	BSA/anti-CYFRA-21–1/APTES/nHfO2@RGO/ITO/glass	DPV	0.16 ng mL−1	0–30 ng mL−1	N/A	ELISARSD: 2.2–8%	15 mn	N/A	N/A	(Kumar et al. 2018)
Interleukin-6 (IL-6)	Aptameric GFET	Potentio-metric	12.2 Pm	0.05 – 0.8 nM	N/A	N/A	400s	30 μL	1:4 dilution with PBS	(Hao et al. 2019)
Interleukin-8 (IL-8)	AuNPs-rGO/ITO/glass	DPV	73 pg mL−1	500 fg mL−1 – 4 ng mL−1	94.15%	N/A	9 min	N/A	Whole saliva	(Verma et al. 2017)
Interleukin-8 (IL-8)	Anti-IL-8/ZnO-rGO/ITO/glass	DPV	51.53 pg mL−1	100 fg/mL – 5 ng mL−1	95 – 100%	N/A	10 min	N/A	1:10 dilution with 1 × PBS	(Verma and Singh 2019)
Prostate specific antigen (PSA)	Graphene-polymer-PS67-b-PAA27-Au	Chemi-resistive	40 fg mL−1	100 fg/mL – 100 ng mL−1	94 – 114%	Self-designed ELISA protocol: 94.02% linearity	1–3 min	10 μL	Whole saliva	(Khan et al. 2018)
Prostate specific antigen (PSA)	MWCNT/His-rGO/thionine/Ab/GCE	DPV	2.8 fg mL−1	10 fg mL−1 – 20 ng mL−1	96.4 – 101.9%	ELISA 97.6% accuracy	25 min	N/A	1:10 dilution with PBS	(Farzin et al. 2019)
3-Nitro-l-tyrosine (3-NT)	ZrO2@rGONCs/GCE	Ampero-metric	0.009 μM	0.025 – 855.2 μM	94.61 – 96.24%	N/A	N/A	N/A	Whole saliva	(Maheshwaran et al. 2020)
8-OHdG	Graphene modified SPE	CV	1.8 nM	6×10−6 – 6×10−4 M	95 – 106%	N/A	N/A	N/A	Whole saliva	(Varodi et al. 2019)

^aS/N = 3, otherwise differently specified

^bvalues obtained in real saliva samples, otherwise differently specified