Fig. 4

A DPV signals of the sandwich electrochemical aptasensor with different concentrations of PD-L1⁺ exosomes (a–k: 5, 1 × 10¹, 1 × 10², 1 × 10³, 1 × 10⁴, 1 × 10⁵, 1 × 10⁶, 1 × 10⁷, 1 × 10⁸, 1 × 10⁹, 1 × 10¹⁰ particles/mL). B DPV signals of the aptasensor incubated with different concentrations of PD-L1⁺ exosomes. Inset: calibration plot of the DPV value vs. the logarithm of the PD-L1⁺ exosome concentration. C DPV responses with different targets: 50 ng/mL BSA (a), 50 ng/mL ALB (b), 50 ng/mL PD-L1 (c), 1 × 10⁷ particles/mL BEAS-2B derived exosomes (d), 1 × 10⁷ particles/mL L-02 derived exosomes (e), 1 × 10⁶ particles/mL A375 derived exosomes (f), a mixture (1 × 10⁶ particles/mL PD-L1⁺ exosomes + 1 × 10⁷ particles/mL BEAS-2B-derived exosomes + 50 ng/mL BSA) (g) and 1 × 10⁶ particles/mL PD-L1⁺ exosomes (h). Error bars: SD, n = 3. D Diagram of exosome recognition model