Figure 3.

Fabrication and characterization of the GPPR-FET sensor

(A and B) TEM images of the RGO and RGO + PLL. Scale bar, 100 nm.

(C) X-ray photoelectron spectroscopic spectra of N_1s for RGO and RGO + PLL.

(D) X-ray photoelectron spectroscopic spectra of P_2p for RGO + PLL and RGO + PLL + GQDs-PMO.

(E) Fluorescence microscope images of GQDs-PMO (PMO labeled with Cy5). Inset images show the fluorescence of control. Scale bar, 100 μm.

(F) I_d−V_g curves of the stepwise functionalization process of the FET chip including RGO assembly, PLL modification, and GQDs-PMO functionalization, respectively.