Aptamer cell sensor based on porous graphene oxide decorated ion-selective-electrode: Double sensing platform for cell and ion.

Enlightened by the emerging cell-ion detection based on ion-selective-electrode (ISE), an aptamer capturing and ISE transducing (AC&IT) strategy is proposed on the porous graphene oxide (PGO) decorated ISE (PGO-ISE), its performances in both cell and ion detections are examined by use of AS1411 targeted A549 cell detection and iodide-ISE as proof-of-concept. Firstly, GO flakes, exfoliated from graphite by modified Hummers method, are cross-linked by thiourea mediated hydrothermal process, to 3-dimension networked PGO which is identified by scanning-electron-microscope, UV-visible absorbance and X-ray photoelectron spectroscopy; its enhancing effect for cell capturing is evaluated by microscopy. Then, PGO-ISE is constructed by drop-coating PGO film on the surface of ISE and followed by covalently anchoring AS1411. Electrochemistry measurements for different state ISE (blank, PGO coated, AS1411 anchored and A549 captured) are performed by our home-made ISE-measuring system. It is demonstrated that the best cell-sensitivity in buffer is - 25.21 mV/log10CA549 (R2 = 0.91), resolution in blood is 10 cells/ml. Interestingly, due to PGO's scaffold protection to the ionophore, I--sensitivity is preserved as - 42.98 mV/pI (R2 = 0.95, pI = -log10(CI)). Theoretical explanations are provided for the double-sensing phenomenon according to basic ISE principle. It is believed the PGO-ISE based aptamer cell sensor will be a promising experimental means for biomedical researches.