Table 4.

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

Nanomaterial-based fluorescent sensors	Sample volume	Incubation time1	Sample	Limit of detection	Ref
Noble metal nanomaterials-based sensors
(A) Salt-induced self-assembly
DNA-CuNCs and cocaine aptamer		15 min		30 ng/mL for cocaine
Aptamer sequence: 5′-GACAAGGAAAATCCTTCAATGAAGTGGGTC-3′	-		-		[61]
DNA-AgNCs and cocaine aptamer fragment 1 & 2 Aptamer sequence (fragment 1): 5′-TTCGTTCTTCAATGAAGTGGGACGACAATGTGGAGGGT-3′ Aptamer sequence (fragment 2): 5′-AGGGACGGGAAGGGAGTCAAGAACGAA-3′	-	15 min	-	30 ng/mL for cocaine	[62]
DNA-AgNCs and cocaine aptamer Aptamer sequence: 5′-CCACTGACCTCAGCATGTCGAGGGAGACAAGGAAAATCCTTCAATGAAGTGGGTCGACATGCTGA-3′	5 μL	1 h	Serum	0.6 ng/mL for cocaine	[63]
DNA-AgNCs and cocaine aptamer Aptamer sequence: 5′-GCTGCAGAATGGGATCTTCATGACAAGGAAAATCCTTCAATGAAGTGGGTCAATTAT-3′	-	30 min	-	91 ng/mL for cocaine	[64]
DNA-AgNCs and ketamine aptamer Aptamer sequence: 5′-TGGGGATGGAGAACTCCCCCCCCCCCC-3′	30 μL	5 min	Blood	60 pg/mL for ketamine	[65]
AgNCs	-	3 min	Urine	No LOD for MDA, MDMA, codeine, meperidine, methcathinone	[67]
(B) FRET-based fluorescent sensors
Cocaine aptamer-modified AuNPs and complementary strand-modified SNPs Aptamer sequence: 5′-CCATAGGGAGACAAGGATAAATCCTTCAATGAAGTGGGTCTCCC-SH-3′	10 μL	40 min	Serum	89 pg/mL for cocaine	[72]
Complementary strand-modified AuNPs and cocaine aptamer Aptamer sequence (cocaine): 5′-Cy5-AAGTGGGGAGACAAGGATAAATCCTTCAATGAAGTGGGTCTCCC-3′	3 μL	1 h	-	No LOD for cocaine	[73]
Cocaine aptamer and AuNPs	5 μL	4 h	-	9.1 ng/mL for cocaine	[74]
Aptamer sequence (cocaine aptamer fragment 1): 5′-AMCA-AGACAAGGAAAA-3′ Aptamer sequence (cocaine aptamer fragment 2): 5′-TCCTTCAATGAAGTGGGTCG-3′
AuNPs	-	3 min	Serum	19 pg/mL (serum) for morphine	[75]
			Urine	17 pg/mL (urine) for morphine
NTS@SNPs	29equivalents	5 min	-	No LOD for methamphetamine	[76]
Cocaine aptamer fragment 1-modified SNPs and cocaine aptamer fragment 2 Aptamer sequence (fragment 1): 5′-biotin-GGGAGTCAAGAAC-BHQ-1-3′ Aptamer sequence (fragment 2): 5′-FAM-GTTCTTCAATGAAGTGTGGGACGACATAMRA-3′	80 μL	25 min	Serum	25 pg/mL for cocaine	[77]
(C) Control-released fluorescent sensors
Pseudorotaxane capped mesoporous SNPs complementary strand-modified NAA and cocaine aptamer	100 μL	2 h	Water	0.94 μg/mL for MDMA	[79]
	100 μL	20 min	Saliva	0.15 μg/mL for cocaine	[80]
Aptamer sequence: 5′-TTTTGGGGGGGGGAGACAAGGAAAATCCTTCAATGAAGTGGGTCTCCAGGGGGGTTTT-3′
Quantum dots-based fluorescent sensors
morphine antibody-labeled CdS@MAA-QDs	0.2 μL	-	-	No LOD for morphine	[82]
Morphine antibody-labeled CdSe/ZnS QDs	100 μL	-	Soup	0.27 ng/mL for morphine	[83]
7-aminoclonazepam antibody-modified CdTe-QDs	-	15 min	Urine	21 pg/mL for 7-aminoclonazepam	[84]
Complementary strand-modified QDs and cocaine aptamer Aptamer sequence: 5′-ACTCATCTGTGATATCTCGGGAGACAAGGAAAATCCTTCAATGAAGTGGGTCTCCC-3′	-	-	-	0.15 μg/mL for cocaine	[85]
Complementary strand-modified QDs and cocaine aptamer Aptamer sequence: 5′-ACTCATCTGTGAATCTCGGGAGACAAGGATAAATCCTTCAATGAAGTGGGTCTCCC-3′	80 μL	5 min	-	36 μg/mL for cocaine	[86]
AuNPs-conjugated cocaine aptamer-modified QDs	25 μL	3 h	Artificial urine	40 pg/mL for cocaine	[87]
Aptamer sequence: 5′-C6-NH2-AGACAAGGAAAATCCTTCAATGAAGTGGGTCG-SH2-C3-3′				480 ng/mL for benzoylecgonine
L-cysteine capped CdS QDs	-	-	Urine	1.8 ng/mL for methamphetamine (fluorescence) 0.086 ng/mL for methamphetamine (chemiluminescence)	[88]
D-Cysteine molecules-functionalized CdSe QDs	-	-	-	17 ng/mL for L-morphine	[89]
Streptavidin-QDs, complementary strand-modified AuNPs and cocaine aptamer Aptamer sequence: 5′-ATCTCGGGAGACAAGGATAAATCCTTCAATGAAGTGGGTCTCCCAAAAAAAAAA-Biotin-3′	10 μL	25 min	-	0.15 pg/mL for cocaine	[90]
Carbon nanomaterials-based fluorescent sensors
Methamphetamine aptamer-modified CDs and CoOOH nanosheets Aptamer sequence: 5′-NH2-(CH2)6-ACGGTTGCAAGTGGGACTCTGGTAGGCTGGGTTAATTTGG-3′	-	20 min		0.48 ng/mL for methamphetamine	[92]
CDs	1.5 mL	5 min	Beverage	2.0 μg/mL for nitrazepam	[93]
CDs-functionalized paper	10 μL	10 min	Urine	1.3 μg/mL for 4-chloroethcathinone	[94]
GQDs	-	1 min	-	1.48 μg/mL for methamphetamine 0.5 μg/mL for morphine	[97]
GQDs with antimorphine (antibody)	-	-	-	18 ng/mL for morphine	[98]
GO and cocaine aptamer fragment 1 & 2 Aptamer sequence (cocaine aptamer fragment 1): 5′-GGGAGTCTCAAGAAC-FAM-3′ Aptamer sequence (cocaine aptamer fragment 2): 5′-GTTCTTCAATGAAGTGGGACGACTAT-3′	-	10 min	Plasma	30 pg/mL for cocaine	[101]
GO and cocaine aptamer Aptamer sequence: 5′-GGGAGACAAGGAAAATCCTTCAATGAAGTGGGTCTCCCTAGTTTTCTAGGGAGAC-PO4-3′	20 μL	20 min	Urine	57 ng/mL for cocaine	[102]
Cocaine aptamer fragment 1-modified GQDs and cocaine aptamer fragment 2-modified AuNPs	1 μL	1 h	Plasma	30 ng/mL for cocaine	[103]
Aptamer sequence (fragment 1): 5′-NH2-(CH2)6-TTTTTGGGAGTCAAGAACGAA-3′			Serum
Aptamer sequence (fragment 2): 5′-SH-(CH2)6-TTCGTTCTTCAATGAAGTGGGACGACA-3′			Saliva
			Urine
Upconversion nanoparticles-based fluorescent sensors
Cocaine aptamer fragment-modified AuNPs and UCNPs	2 μL	40 min	Rat plasma	LOQ: 3 ng/mL (aqueous solution) for cocaine	[105]
Aptamer sequence: 5′-SH-TTTTTACAGCAGGGTGAAGTAACTTCTTG-3′			Saliva	LOQ: 15 ng/mL (saliva) for cocaine
Cocaine aptamer-modified UCNPs Aptamer sequence: 5′-NH2-TTTTTTGACAAGGAAAATCCTTCAATGAAGTGGGTC-3′	0.1–10 μg	30 min	Fingerprints	0.1 μg for cocaine	[106]

Abbreviation: CuNCs: copper nanoclusters; AgNCs: silver nanoclusters; MDA: 4,5-methylene-dioxy amphetamine; MDMA: 3,4-methylene dioxy methamphetamine; SNPs: silica nanoparticles; NTS: 4-thiophene-N-propyl(trithoxysilane)1,8-naphthalimide; NAA: nanoporous anodic alumina; MAA: mercaptoacetic acid; CDs: carbon dots; CoOOH: cobalt oxyhydroxide; GQDs: graphene quantum dots; GO: graphene oxide; UCNPs: upconversion nanoparticles.

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