Construction and Application of Graphene Oxide-Bovine Serum Albumin Modified Extended Gate Field Effect Transistor Chiral Sensor

Abstract

Chirality is an essential natural attribute of organisms. Chiral molecules exhibit differences in biochemical processes, pharmacodynamics, and toxicological properties, and their enantioselective recognition plays an important role in explaining life science processes and guiding drug design. Herein, we developed an ultra-sensitive enantiomer recognition platform based on an extended-gate metal-oxide semiconductor field-effect-transistor (Nafion-GO@BSA-EG-MOSFET) that achieved effective chiral resolution of ultra-sensitive Lysine (Lys) and α-Methylbenzylamine (α-Met) enantiodiscrimination at the femtomole level. Bovine serum albumin (BSA) was immobilized on the surface of graphene oxide (GO) through amide bond coupling to prepare the GO@BSA complex. GO@BSA was drop-cast on deposited Au surfaces with a Nafion solution to afford the extended-gate sensing unit. Effective recognition of chiral enantiomers of mandelic acid (MA), tartaric acid (TA), tryptophan (Trp), Lys and α-Met was realized. Moreover, the introduction of GO reduced non-specific adsorption, and the chiral resolution concentration of α-Met reached the level of picomole in a 5-fold diluted fetal bovine serum (FBS). Finally, the chiral recognition mechanism of the as-fabricated sensor was proposed.

Keywords: bovine serum albumin; chiral sensing; extended-gate field effect transistor; graphene oxide.

Figure 1

Preparation process of GO@BSA.

Figure 2

Fourier Transform infrared spectroscopy (FTIR) (A) and UV-vis (B) spectroscopy of GO, GO–COOH, BSA, GO@BSA.

Figure 3

X-ray photoelectron spectroscopy (XPS) fully scanned spectra of GO and GO@BSA.

Figure 4

Cyclic voltammogram (CV) (A) and Nyquist plots (B) in the electrolyte containing 5 mM [Fe(CN)₆]^4-/3- and 0.1 M KCl. Scan rate of CV, 20 mV·s⁻¹; frequency range of Nyquist plots, 10⁵ to 10⁻² Hz. B inset: Equivalent circuit.

Figure 5

(A) Schematic diagram of the Nafion–GO@BSA–EG-MOSFET sensor and (B) structures of chiral compounds.

Figure 6

Real time detection curve of Nafion–GO-EG-MOSFET and Nafion–GO@BSA–EG-MOSFET for (A,B) Trp, (C) MA and (D) TA enantiomers.

Figure 7

Chiral recognition of positively charged α-Met (A) and Lysine (B) enantiomers by Nafion–GO@BSA-EG-MOSFET.

Figure 8

Comparison of chiral recognition ability of the Nafion–GO@BSA–EG-MOSFET platform for α-Met enantiomers in 1% PBS (A) and 20-fold (B), 10-fold (C) and 5-fold (D) diluted FBS, respectively.

Figure 9

Recognition performance of Nafion–BSA-EG-MOSFET for α-Met enantiomers in 1% PBS (A) and 20-fold diluted FBS (B).

Figure 10

Non-real-time detection of Trp by Nafion–GO@BSA–EG-MOSFET (A,B) and schematic illustration of chiral recognition mechanism (C,D).