Figure 2: Characterization of graphene–hemin conjugate.
From: Real-time electrical detection of nitric oxide in biological systems with sub-nanomolar sensitivity
(a) Ultraviolet–visible spectrum of graphene before and after hemin immobilization. Black: bare graphene; red: graphene after immersed in hemin–DMSO solution, blue: hemin in DMSO solution. (b) AFM image of graphene after hemin immobilization. Scale bar, 1 μm. (c) Raman spectra of graphene before and after hemin functionalization. Black: bare graphene; blue: graphene after immersed in DMSO, with an offset of 0.2; red: graphene–hemin conjugate, with an offset of 0.4. (d) Real-time electrical measurement with NO precursor solution directly added onto a graphene–hemin device inside a PDMS well filled with PBS solution. Graphene–hemin device (red) and bare graphene device (black) were measured in parallel within the same PDMS well. Solution A is 0.01 M NaOH. B is NO precursor in PBS bubbled with N2 for 2 h (essentially the same as C but with NO removed). C is NO precursor in NaOH solution (both B and C are 1 μM after diluted in the PDMS well).
