Table 3.

Various nanomaterial-based colorimetric sensors for analysis of illicit drugs.

Nanomaterial-based colorimetric sensors	Sample volume	Incubation time1	Sample	Limit of detection	Ref.
Small molecular-based AuNP sensors
Citrate-capped AuNPs	1 mL	-	Bone Bone marrow Soil	0.62 μg/mL for codeine sulfate	[34]
Citrate-capped AuNPs	1.2 mL	10 min	Urine	0.3 μg/mL for codeine 0.3 μg/mL for methadone 0.29 μg/mL for morphine 6.7 μg/mL for noroxycodone 0.31 μg/mL for thebaine	[35]
Citrate-capped AuNPs	-	10 min	Serum Urine	0.15 μg/mL for morphine	[36]
Melamine-modified AuNPs	-	3 min	Blood Bone Bone marrow	0.28 ng/mL for clonazepam	[40]
Melamine-modified AuNPs	-	10 min	Serum	2.7 ng/mL for codeine	[41]
			Urine	4.9 ng/mL for morphine
Aptamer-based AuNP sensors
(A) Oligonucleotide-assisted aggregation
Complementary strand-modified AuNPs and cocaine aptamer Aptamer sequence: 5′-ACTCATCTGTGAATCTCGGGAGACAAGGATAAATCCTTCAATGAAGTGGGTCTCCC-3′	-	10 s	-	No LOD (for cocaine)	[44]
Cocaine aptamer fragment 1-modified AuNPs and cocaine aptamer fragment 2-modified AuNPs Aptamer sequence (fragment 1): 5′-GTTCTTCAATGAAGTGGGACGACATTTTTTTTTT-SH-3′ Aptamer sequence (fragment 2): 5′-GGGAGTCAAGAACTTTTTTTTTT-SH-3′	10 μL	30 min	Fingerprints	90 ng for cocaine	[45]
(B) Salt-induced self-assembly
AuNPs and cocaine aptamer fragment 1 & 2 Aptamer sequence (fragment 1): 5′-GTTCTTCAATGAAGTGGGACGACA-3′ Aptamer sequence (fragment 2): 5′-GGGAGTCAAGAAC-3′	2 μL	2–3 min	-	0.6 μg/mL for cocaine	[46]
AuNPs and cocaine aptamer Aptamer sequence: 5′-GGGAGACAAGGAAAATCCTTCAATGAAGTGGGTCGACA-3′	20 μL	30 min	Urine	0.3 ng/mL for cocaine	[47]
AuNPs and cocaine aptamer	18.2 μL	30 min	-	0.25 mg/mL for cocaine	[48]
Aptamer sequence: 5′-GGCGACAAGGAAAATCCTTCAACGAAGTGGGTCGCC-3′
AuNPs and cocaine aptamer fragment 1 & 2 Aptamer sequence (fragment 1): 5′-ACAGCAGGGTGAAGTAACTTCTTG-3′ Aptamer sequence (fragment 2): 5′-GGGAGTCAAGAAC-3′	1 μL	5 min	-	2.36 μg for cocaine	[49]
AuNPs and methamphetamine aptamer Aptamer sequence: 5′-ACGGTTGCAAGTGGGACTCTGGTAGGCTGGGTTAATTTGG-3′	120 μL	5 min	Urine	0.12 μg/mL for methamphetamine	[50]
Others
AgNPs	-	30 min	Hashish	52 ng/mL for cannabidiol 77 ng/mL for cannabinol 65 ng/mL for tetrahydro-cannabinol	[52]
Complementary strand-modified Au@AgNPs and methamphetamine/cocaine aptamer	10 μL	-	Urine	15 pg/mL for methamphetamine	[53]
Aptamer sequence (methamphetamine): 5′-ACGGTTGCAAGTGGGACTCTGGTAGGCTGGGTAATTTGG-3′ Aptamer sequence (cocaine): 5′-GGGAGACAAGGATAAATCCTTCAATGAAGTGGGTCGATA-3′				0.15 ng/mL for cocaine
Complementary strand (methamphetamine)-modified Au@AgNPs and methamphetamine aptamer	5 μL	30 min	Waste water	75 pg/mL for methamphetamine	[54]
Complementary strand (cocaine)-modified AuNPs and cocaine aptamer Aptamer sequence (methamphetamine): 5′-ACGGTTGCAAGTGGGACTCTGGTAGGCTGGGTAATTTGG-3′ Aptamer sequence (cocaine): 5′-GGGAGACAAGGATAAATCCTTCAATGAAGTGGGTCGATA-3′				1 ng/mL for cocaine
Cocaine antibody-modified MNPs	80 μL	10 min	Urine	5 ng/mL for cocaine	[55]
Benzoylecgonine mAb conjugated AuNPs	100 μL	-	Synthetic saliva	10 ng/mL for cocaine	[56]

Abbreviation: AuNPs: gold nanoparticles; AgNPs: silver nanoparticles; Au@AgNPs: gold-silver core-shell nanoparticles.

¹Incubation time: the time of recognition of the analyte in sensing procedure.