Table 4 Biosensors with nucleic acid aptamer immobilization covalent approach

DEP chips GCE

0.05 M EDC (3 µL) and 0.03 M sulfo-NHS in PBS (pH 7) for 1 h to activate carboxyl acid groups. PBS wash

DNA (26 base)

5′-NH₂-(CH₂)₆-ACCAGGCGGCCGCACACGTCCTCCAT-3′ [N/A]

3 µL DNA probe at optimized concentration deposited overnight in humidified air at RT in PBS (pH 7)

5′-ATG-GAGGACGTGTGCGGCCGCCTGGT-3′

N/A

Incubated with gentle stirring in 100 µL with DNA target for 30 min at 42 °C in (TSC1 buffer)

CV and EIS in 0.01 M PBS buffer containing K₃[Fe(CN)₆]/K₄[Fe(CN)₆] (10 mM)

1:1 molar ratio

N/A

N/A

[136]

GCE/rGO/AMEL

0.2 M EDC in MES buffer and 0.5 M NHS in 0.1 M PBS treatment for 1 h to activate carboxyl acid groups of rGO. PBS wash

AMGX (17 base)

3′-TATCCC

AGATGT

TTCTC-NH₂-5′ [1 µM]

80 µL DNA probe dispensed on inverted surface covered with a glassy cap of for 1 h at 25 °C

AMGX: 3′-GAGAAACATCTGGGATA-5′ [10 zM–10 fM]

With PCR

0.5 mM [Fe(CN)₆]^3−/4− in 0.1 M KCl

3 days

RSD = 5.014%

[48]

Anodized epitaxial graphene electrode

0.2 M EDC and 0.5 M NHS for 1 h. Rinsed with ultra-pure water

DNA (30 base)

NH₂-C₁₂-5′-GCACCTGACTCCTTGGAGAAGTCTGCCGT-3′ [N/A]

DNA solution added and incubated overnight

5′-ACG GCA GAC TTC TCC ACA GGA GTC AGG TGC-3′ [50 fM–1 µM]

Electrode treated with 100 μL ssDNA target solution for 40 min at 42 °C

EIS in PBS/14 mM NaCl/0.27 mM KCl/1 mM Na₃PO₄ and 0.176 mM K₃PO₄)

N/A

7% for 1 nM

[137]

MnTPP/rGO-GCE

20 mM EDC and 32 mM NHS in 10 mM PBS for 1 h at room temperature

ssDNA (25 base)

NH₂-C₆-5′-TCAATCTCG

GGAATCTCA

ATGTTAG-3′ [1 µM]

Add a solution of ssDNA probe for

1 h at room temperature in the activation solution

5′-CTAACATTG AGATTCCCGAGATTGA-3′ [100 aM–1 nM]

5 μL DNA target deposited for 40 min at 47 °C.

0.1 M KCl with 5 mM [Fe(CN)₆]³⁻/[Fe(CN)₆]⁴⁻

High

RSD < 3%

[138]

Gold-wire electrode (AuE)

N/A

Thiol-ssDNA

(23 base)

5′-SH-(CH₂)₆-AGTCAGTGT GGAAAATCT CTAGC-3′ [N/A]

2 µL of ssDNA

dropped on AuE surface and kept 15 min in water at room temperature.

Then immersed in dispersed graphene for 15 min

DA [1–50 nM]

N/A

DPV in 0.2 M of PBS buffer (pH 7.4)

1 week; 90% in 2 weeks

3.5% for 1 µM DA

[139]

MoS₂/graphene/GCE

N/A

DNA (15 base)

5′-AGTGATTTT AGAGAG-3′ [1 µM]

20 µL pDNA dropcast on MoS₂/graphene/GCE. Dried in oven for 35 min at 57 °C

5′-TCA CTA AAA TCT CTC-3′ [0.1–100 fM]

20 µL cDNA dropcast on GCE, dried for 30 min at 57 °C. Treated with 1 M KCl solution 0.2 M K₃[Fe(CN)₆] at - 0.7 V for 300 s to release the dsDNA.

1.0 M KCl solution containing 0.2 M K₃ [Fe(CN)₆] at a scan rate of 0.10 V/s from 0.6 to − 0.3 V

N/A

N/A

[140]

AuNP/graphene–VS₂/GCE

N/A

DNA (S1)

(21 base)

5′-HS-(CH₂)₆-TTGCCCGTTTACTTTGGGTCT-3′ [9.6 µM]

AuNPs/grapheneVS2/GCE was incubated in HS-DNA for 3 h at room temperature

5′-AGA CCC AAA GTA AAC GGG CAA-3′ [0.5–500 pM]

Immersion of the electrode into target DNA at room temperature for 60 min

1 mmol/L [Fe(CN)₆]^3−/4− containing 0.1 mol/L KCl

92.1% after 1 week

RSD = 4.3%

[141]

GO-PGE

N/A

HBV DNA probe: (20 base)

5′-NH₂-(CH₂)₆-AATACCACA TCATCCATA TA-3′ [40 µg/mL]

GO-PGEs were immersed in 110 µL of amino linked HBV probe solution prepared in ABS for 1 h

5′-TAT ATG GAT GAT GTG GTA TT-3′ [160 µg/mL]

Probe immobilized electrodes immersed in 110 µL target for an hour

EIS in 2.5 mmol/L K₃[Fe(CN)₆]/K₄[Fe(CN)₆] (1:1) with 0.1 mol/L KCl DPV in ABS

N/A

RSD = 14.2%

[142]

GQD-PGE

N/A

ssDNA-1

(35 base):

5′-TCTCTCAGT CCGTGGTAG GGCAGGTTG GGGTGACT-3′ [500 nM]

Electrode immersed in 70 μL 10 mM Tris–HCl buffer containing ssDNA-1 for 1 h

5′-AG TCA CCC CAA CCT GCC CTA CCA CGG ACT GAG AGA-3′ [100–500 nM]

Target first added to solution of ssDNA-1 and incubated for 1 h before the immobilization

DPV in 10 mM tris–HCl buffer solution containing 5 mM [Fe(CN)₆]^3−/4− pH 6

N/A

N/A

[143]

GCE-APTES-rGO

N/A

MRSA DNA probe (30 base)

5′-ATGATTATG GCTCAGGTA CTGCTATCC ACC-3′ [10 µM]

5 μL DNA dropped onto GCE-APTES-rGO electrode then capped with a centrifuge tube and kept at room temperature for 6 h

5′-GGT GGA TAG CAG TAC CTG AGC CAT AAT CAT-3′ [10 µM]

5 μL target DNA solution dropped onto GCE’s and droplet kept at room temperature for 30 min

0.1 M KCl containing 5 mM [Fe(CN)₆]^3−/4− (1:1)

N/A

N/A

[144]

PTCA/CCG-GCE

200 mM EDC and 50 mM NHS in MES buffer

cast on PTCA/

CCG-GCE surface to activate the carboxyl group for 1 h. Rinsed with 10 mm Tris buffer (pH 7.4)

AS1411 (32 base) 5′-GGTGGT GGTGGTTGT GGTGGTGGT GGTTTTTT-NH2-3′ [1 µM]

DNA dropcast on the surface and then incubated for 4 h

Cancer cells

[1 µM]

The surface was washed by buffer and subsequently hybridized with aptamer DNA in 10 mM Tris, 2.5 mM MgCl₂, 140 mM KCl (pH 7.4) for 1 h

CV in 10 mM K₃[Fe(CN)₆], 1.0 M KCl; EIS in 10 mM K₃[Fe(CN)₆]/K₄[Fe(CN)₆] (1:1) mixture with 1.0 M KCl

N/A

N/A

[145]