Table 3.
Biosensors with nucleic acid aptamer immobilization using noncovalent approach
| Electrode | DNA aptamer probe [concentration] | Immobilization (buffer) | Wash and drying conditions | Analyte target [concentration] | Aptamer-analyte hybridization (buffer) | Washing and drying | Electrolyte | Stability | Reproducibility | References |
|---|---|---|---|---|---|---|---|---|---|---|
| DEP-GO; DEP-ERGO | THR-APT: 5′-TTT TTT TTT TTT TTT GGT TGG TGT GGT TGG-3′ [10 µM] | 3 μL of THR-APT deposited onto modified electrode surface for 10 min at 60 °C in (PBS) |
Wash in PBS gentle stirring Dry at room temperature |
THR [40.5 nM] | Incubated in 100 µL with THR for 60 min. at 37 °C in (Tris buffer) |
Tris buffer solution at 37 °C 2× |
EIS in 10 mM K3[Fe(CN)6]/K4[Fe(CN)6] in TBS (pH 8.2) | N/A | N/A | [107] |
| Graphene modified DEP chip | hpDNA [10 µM] | 3 μL hpDNA probe drop onto modified electrode surface for 10 min at 60 °C in (TSC1) |
Wash in TSC1, gentle stirring Dry at room temperature |
cDNA target [30 nM] |
Incubated in 100 µL with DNA target for 30 min at 55 °C in (TSC1) |
TSC2 buffer at 42 °C 2× | EIS in 0.1 M PBS containing 10 mM K3[Fe(CN)6]/K4[Fe(CN)6] | N/A | Low for G-SL RSD = 31% | [127] |
| rGO-graphene double-layer electrode |
Fluorescent dye labelled HIV1 gene aptamer 5ʹ-AGT CAG TGT GGA AAA TCT CTA GC-carboxyfluorescein-3ʹ [1 µM] |
10 µl ssDNA probe deposited onto modified electrode surface at 35 °C for 30 min in (PBS) | Wash in nuclease free water 15× | 5ʹ-GCT AGA GAT TTT CCA CAC TGA CT-3ʹ [0.01–100 nM] | Dripped 10 µL target cDNA onto electrode surface at room temperature for 1 h in (PBS) | Nuclease free water | DPV, CV in 10 mM ferricyanide aqueous solution (1 M KCl as support electrolyte) | ~ 3 h | RSD = 6.2–8.1% | [135] |
| ERGO (DEP chip) | hpDNA: 5′-ATG GAG ACC AGG CGG CCG CAC ACG TCC TCC AT-3′ [10 µM] | hpDNA probe dry-adsorbed onto modified electrode surface at 60 °C for 10 min in (PBS) |
Wash in PBS 1× Dry at room temperature |
ssDNA target: 5′-ATG GAG GAC GTG TGC GGC CGC CTG GT-3′ [0.01–10 nM; 300 nM] | Incubated in 100 µL with ssDNA target for 40 min at 55 °C in (SSC) | SSC buffer at 42 °C 2× | EIS in 10 mM of [Fe(CN)6]3−/4− as redox probe in 0.1 M PBS solution. | N/A | N/A | [108] |
| Graphene microarray grown by CVD | 5′-AGC TTC ATA ACC GGC GAA AGG CTG AAG CT-3′ [10 µM] | 10 μL DNA probe adsorbed on graphene surface for 2 h in (10 mM PBS/150 mM NaCl/50 mM MgCl2) | Wash in buffer | 5′-AGC TTC AGC CTT TCG CCG GTT ATG A-3′ [5 pM to 50 nM] |
Incubation in DNA target solution N/A |
N/A | CV and EIS in 1 mM K3Fe(CN)6, 1 mM K4Fe(CN)6 and 10 mM PBS | N/A | N/A | [126] |