Table 1.
Electrochemical biosensing strategies for determination of ctDNAs and specific features.
| Electrode | Fundamentals | Target | Technique | Linear range | LOD | Assay Time | Sample | Ref. |
|---|---|---|---|---|---|---|---|---|
| Determination of ctDNA | ||||||||
| AuE | THMS probe and TdT and RNase HII dual amplification | KRAS G12DM ss-ctDNA | DPV (MB) | 0.01 fM-1 pM | 2.4 aM | ~6.5 h + Cp-AuE (4 h) | DNA extracted from plasma of CRCP and HD | [20] |
| Tumor-specific mutations in ctDNA | ||||||||
| Array of 16 bare AuE chips | Sandwich hybridization format using paired capture and FITC-Dp further conjugated with HRP-anti-FITC Fab fragments | EGFR mutations | Chronoamperometry (TMB/H2O2) | — | — | ≤ 10 min | Saliva and plasma samples of NSCLC patients | [21] |
| rGO-CMC-modified SPCE | Direct hybridization using an amino and biotin dually labeled hairpin specific DNA Cp | Single base mutation in TP53 | Amperometry (TMB/H2O2) | 0.01–0.1 μM | 2.9 nM (29 fmol in 10 μL) | 45 min + Cp-SPCE (2 h 15 min) | Spiked untreated human serum and saliva samples and cDNA from MCF-10A, MCF-7 and SK-BR-7 cells | [22] |
| GCE | Direct hybridization at Cp/PEG/AuNPs/GCE | Single base mutation in BRCA1 | EIS ([Fe(CN)6]3-/4-) | 50.0 fM–1.0 nM | 1.72 fM | 2 h + Cp/PEG/AuNPs/GCEs (33 h) | Spiked human serum samples | [23] |
| AuE | HCR at Cp-AuE | Single base mutation in BRCA1 | DPV (RuHex) | 1 aM–10 pM | 1 aM | 4 h 45 min + Cp-AuE (3 h) | Spiked human serum samples | [24] |
| NMEs modified with PNA probes | Direct hybridization in connection with a clutch probe strategy | Single base mutation in KRAS and BRAF in ctDNAs | DPV (Ru(NH3)63+/Fe(CN)63−) | — | 0.01% mutation in wild-type DNA | 50 min + PNA probes-NMEs (12 h) | ctDNA from serum collected from lung cancer and melanoma patients |
[25] |
| Epigenetic changes in ctDNA | ||||||||
| AuE | Paired-end tagging amplification | 5-mC (—) |
Chronoamperometry (H2O2/TMB) |
— | 40 pg (genomic DNA) | ~1.5 h (once the modified electrode was prepared) | gDNA extracted from plasma of NSCLC patients | [26] |
| SPCE | Immunosensor and DNA Dp-modified Fe3O4/TMC/Au nanocomposite as tracing tags | 5-mC/RASSF1A | DPV (AuNPs) |
1 × 10−14-5 × 10−9 M | 2 × 10−15 M | 2 h 40 min (once the PT/anti-5mC -SPCE was prepared) | Spiked plasma | [27] |
| AuE | Bisulfite + self-assembled tetrahedral DNA probes to capture amplicons generated by aMSP | 5-mC/p16INK4a | Chronoamperometry (H2O2/TMB) | 3–150 pg synthetic target methylated DNA | One methylated DNA molecule in the presence of a 1000-fold excess of unmethylated alleles | aMSP (~42 min) + 45 min (once the AuE was modified with the tetrahedral probes) |
cDNA extracted from plasma samples of lung cancer patients | [28] |
| SPCE | Immunopurification (anti-5-mC-MBs) Immunodetection(b-DNA-Cp-MBs) | 5-mC/global (anti-5-mC) and gene-specific (b-DNA-Cp-MBs, MGMT and RASSF1A) | Amperometry (H2O2/HQ) | Global (anti-5-mC-MBs): 23−24,000 pM Gene-specific (b-DNA-Cp-MBs): 139−5000 pM (RASSF1A) 87–2500 pM (MGMT) |
Global (anti-5-mC-MBs): 6.8 pM Gene-specific (b-DNA-Cp-MBs): 42 pM (RASSF1A) 26 pM (MGMT) |
Global: 45 min (once the anti-5-mC-MBs were prepared) Gene-specific: 1 h (once b-DNA-Cp-MBs were prepared) |
Spiked urine, plasma and saliva | [29] |
| SPCE | Immunopurification (anti-5-mC or anti-5-hmC-MBs) | 5-mC and 5-hmC/global and gene-specific (MGMT and RASSF1A) | Amperometry (H2O2/HQ) |
Global: 5-mC: 14–2500 pg 5-hmC: 0.04–0.55% Gene-specific: 5-mC: 4.0−250 pM (MGMT) 5-hmC: 1.44−100 pM (MGMT) |
Global: 5-mC: 4.0 pg 5-hmC: 0.004% Gene-specific: 5-mC: 1.2 pM (MGMT) 5-hmC: 0.43 pM (MGMT) |
Global: 45 min (once the anti-5-mC or anti-5-hmC-MBs were prepared) Gene-specific: 90 min (once the anti-5-mC or anti-5-hmC-MBs were prepared) |
gDNA extracted from cell lines paraffin-embedded tissues from CRCP and direct determination 1/5 diluted serum from breast and lung cancer patients | [30] |
| SPCE | Sandwich structure based on PNA probe and anti-5-mC antibody AuNPs and LPA for double signal amplification | Tumor-specific mutations and 5-mC methylation of PIK3CA gene | SWV (lead ions) | 50 fM–10000 fM | 10 fM | 1 h 5 min + PNA-AuNPs conjugates (68.5 h) + LPA-anti-5-mC bioconjugates (6 h) | Spiked human plasma samples | [31] |
| Cancer-related viral DNA sequences | ||||||||
| NPGE | Sandwich hybridization approach involving a thiolated Cp and amino-labeled Dp further conjugated with Fc | HBV DNA | DPV (Fc) | 3 × 10−5–1 × 10−3 M | 0.8 μM | 9 h 20 min + Cp-NPGE (1 h 15 min) | Blood samples from infected people | [32] |
aMSP: asymmetric methylation-specific PCR; AuE: gold electrode; AuNPs: gold nanoparticles; cDNA: circulating DNA; Cp: capture probe; CRCP: colorectal cancer patients; Dp: detector probe; DPV: differential pulse voltammetry; EGFR: epidermal growth factor receptor; EIS: electrochemical impedance spectroscopy; Fc: ferrocene; FITC: fluorescein isothiocyanate; GCE: glassy carbon electrode; gDNA: genomic DNA; HBV: Hepatitis B virus; HCR: hybridization chain reaction; HD: healthy donors; 5-hmC: 5-hydroxymethylcytosine; HQ: hydroquinone; HRP: horseradish peroxidase; LOD: limit of detection; LPA: lead phosphate apoferritin; MB: methylene blue; MBs: magnetic beads; 5-mC: 5-methylcytosine; NME: nanostructured microelectrode; NPGE: nanoporous gold electrode; NSCLC: non-small cell lung cancer; PEG: polyethylene glycol; PNA: peptide nucleic acid; PT: polythiophene; rGO-CMC: reduced graphene oxide−carboxymethylcellulose; RuHex: Ru(NH3)63+; SPCE: screen-printed carbon electrode; SWV: square wave voltammetry; TdT: terminal deoxynucleotidyl transferase; THMS: triplehelix molecular switch; TMB: 3,3´,5,5´-tetramethylbenzidine; TMC: N-trimethyl chitosan.