Table 5.

Graphene biosensors for the detection of drugs and hazardous substances in saliva

Biomarker	Sensing Platform	Detection Method	LODa	Detection Range	Recoveryb	Assay Time	Sample Volume	Preparation	Reference
Antipyrine (ANT)	TiO2-GO modified CPE	Square wave voltammetry (SWV)	3.00 × 10−9 M	1.2 × 10−8 – 8 × 10−5 M	99.62%	N/A	N/A	Dilution with 5 mL BRB	(Mohamed et al. 2017)
Arsenic	MnO2POT/rGO/GCE	DPV	0.042 ppb	0.01 – 0.9 ppb	99.8–101.8%	N/A	N/A	3-fold dilution with nitric acid	(Ponnaiah et al. 2019)
Benzocaine (BEN)	TiO2-GO modified CPE	SWV	2.48 × 10−7 M	1 × 10−6 – 1 × 10−4 M	99.62%	N/A	N/A	Dilution with 5 mL BRB	(Mohamed et al. 2017)
Cotinine	PtNP-graphene modified SPCE	CV	0.33 nMc	1–100 nMc	N/A	12 min	N/A	Whole saliva	(Parate et al. 2019)
Ketamine	KT-MIM/MOFs@G/SPE	DPV	4.0×10−11 mol L−1	1.0×10−10 – 4.0×10−5 mol L−1	98 – 116%	5 min	N/A	1:10 dilution with DI water	(Fu et al. 2019)

^aS/N = 3, otherwise differently specified

^bvalues obtained in real saliva samples, otherwise differently specified

^cin saliva