Skip to main content
. 2019 Aug 30;19(17):3762. doi: 10.3390/s19173762

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.