Table 2.
Electrochemical biosensors that target cancer-specific biomarkers present on the surface of EVs
| Biomarker | Biorecognition element | Cell lines (cancer) | Isolation technique(s) | Signal amplification strategy | Electrochemical technique (electrode) | LOD (EVs/mL) | Dynamic range (EVs/mL) | Real samples | Ref |
|---|---|---|---|---|---|---|---|---|---|
| EGFR | Peptide | U87 (glioblastoma) | Differential centrifugation | MOFs | SWV (GE) | 7.83 × 106 | 9.5 × 106 to 1.9 × 1010 | Human serum | [72] |
| EGFR, CD9, CD63 | Affibody | H1975 (NSCLC) | Size-exclusion chromatography | None | Electrokinetic detection | 2.8 × 108 | 0.8 × 109 to 3.5 × 109 | No | [71] |
| MUC1 and CD63 | Aptamer | MCF-7 (breast) | Exo-Spin™ kit (Promega) | HCR | DPV (ITO) | 3.0 × 104 | 1 × 105 to 3.7 × 108 | Serum of breast cancer patients | [79] |
| CA-125 and CD9 | Antibody | OVAR3 (ovary) | Total Exosome Isolation Reagent (Invitrogen) | None | DPV (PCE) | 7.1 × 108 | NS | No | [80] |
| PTK7 and PSMA | Aptamer | CCRF-CEM (lymphoblastic leukemia) | Differential centrifugation | Cyclic enzymatic amplification | DPV (GE) | 9.2 × 105 | 4 × 106 to 8 × 1010 | No | [81] |
| EpCAM and CD63 | Aptamer | MCF-7 (breast) | Centrifugation | 3D-DNA walker | DPV (GE) | 1.3 × 104 | 5.0 × 104 to 1.0 × 1010 | FBS | [82] |
| EpCAM, CD9 | Antibody | LNCaP (prostate) | Centrifugation | None | CV (GE) | 3.0 × 105 | NS | Undiluted serum, urine | [77] |
| EpCAM and CD63 | Aptamer | MCF-7 (breast) | Centrifugation + filtration | DNA walker, Ag@C nanocomposites | DPV (GE) | 4.0 × 104 | 105 to 75 × 106 | 30–60% FBS | [83] |
| EpCAM | Aptamer | MCF-7 (breast) | UC | mHCR | CA (GE) | 2.85 × 105 | 5 × 105 to 1 × 108 | Human serum | [75] |
CA, chronoamperometry; CV, cyclic voltammetry; DPV, differential pulse voltammetry; EGFR, epidermal growth factor receptor; EIS, electrochemical impedance spectroscopy; EpCAM, epithelial cell adhesion molecule; FBS, fetal bovine serum; GE, gold electrode; HCR, hybridisation chain reaction; ITO, indium-tin oxide; LNCaP, lymph node carcinoma of the prostate; mHCR, multidirectional HCR; MOFs, metal–organic frameworks; MUC1, mucin 1; NSCLC, non-small-cell lung cancer; PCE, paper-based carbon electrode; PSMA, prostate-specific membrane antigen; PTK7, tyrosine kinase–like 7; RCA, rolling circle replication; SWV, square-wave voltammetry; UC, ultracentrifugation