Label-free electrochemical cancer cell detection leveraging hemoglobin-encapsulated silver nanoclusters and Cu-MOF nanohybrids on a graphene-assisted dual-modal probe

Abstract

Breast cancer detection at an early stage significantly increases the chances of successful treatment and survival. This study presents an electrochemical biosensor for detecting breast cancer cells, utilizing silver nanoclusters encapsulated by hemoglobin and Cu (II)-porphyrin-metal organic framework (BioMOF) in a graphene-incorporated nanohybrid probe. This Hb-AgNCs@MOF-G probe demonstrates high electrochemical activity, superior dispersity, porosity, and a large surface area for effective functionalization. Using a green ultrasonic-assisted stirring method, we fabricate ultra-small 5 nm particles that readily immobilize on a glassy carbon electrode, generating a detection signal when interacting with ferricyanide/ferrocyanide redox probes. The resulting immunosensor detects as few as 2 cells/mL using Electrochemical Impedance Spectroscopy (EIS) "signal on" and 16 cells/mL via Square Wave Voltammetry (SWV) "signal off", within a broad range of cell concentrations (10²-5 × 10⁴ cells/mL). Our designed sensor shows improved selectivity (5- to 16-fold) and robust detection in human blood with a recovery efficiency between 94.8-106% (EIS method) and 95.4-111% (SWV method). This sensor could streamline early cancer diagnosis and monitor patient treatment without requiring labelling or signal amplification. As a pioneering endeavor, we've utilized integrated porous MOFs with Hb-encapsulated silver nanoclusters in cancer detection, where these components collectively enhance the overall functionality.

Figure 1

Schematic illustration of breast cancer cell detection with the designed Hb-AgNCs@MOF-G Nanohybrid .

Figure 2

(A) FTIR analysis for the materials: Hb, Go, Hb-AgNCs, Hb-AgNCs/G, MOF-G, Hb-AgNCs@MOF-G; (B) Raman spectra data for the (a) GO, (b) Hb-AgNCs/G, (c) MOF-G and (d) Hb-AgNCs@MOF-G; (C) UV–Vis spectra of (a) Hb-AgNCs/G, (b) MOF-G and (c) Hb-AgNCs@MOF-G.

Figure 3

TEM image of (A) MOF-G, (B) Hb-AgNCs/G and (C) Hb-AgNCs@MOF-G. FE-SEM images of (D) Hb-AgNCs@MOF-G. (E and F) EDS mapping and (G) elemental analysis images of the nanocomposite. (H) Zeta potential measurements of the as-prepared graphene materials.

Figure 4

Electrochemical characterization of Nanocomposite by (A) Nyquist plots, (B) SWV plot and (C) CV curves of bare GCE (a), GCE/Hb-AgNCs@MOF-G (b), GCE/Hb-AgNCs@MOF-G/Herceptin (c), GCE/Hb-AgNCs@MOF-G/Herceptin/SKBR3 (d), in 0.1 M PBS containing 5 mM K₃[Fe (CN)₆]/K₄[Fe (CN)₆].

Figure 5

(A) Herceptin antibody concentration optimization. (B) ΔR_ct values of Hb-AgNCs@MOF-G-based electrochemical sensor for SKBR3, MCF-7, MDA-MB231 and HFF cells and concentration of 50 cells, (C) EIS responses of the Hb-AgNCs@MOF-G-based sensor with different SKBR3 concentrations (1 × 10², 5 × 10², 1 × 10³, 15 × 10², 25 × 10², 5 × 10³, 1 × 10⁴, 25 × 10³ and 5 × 10⁴ cells/mL). (D) Dependence of ΔR_ct on the concentration of SKBR3. (E) SWV responses of the Hb-AgNCs@MOF-G-based sensor with different SKBR3 concentrations. (F) Dependence of ΔI on the concentration of SKBR3. (G) Reproducibility of the Hb-AgNCs@MOF-G-based sensor for detecting HER2 + cells with a concentration of 50 cells.