Identification of volatile biomarkers of gastric cancer cells and ultrasensitive electrochemical detection based on sensing interface of Au-Ag alloy coated MWCNTs

Abstract

Successful development of novel electrochemical biosensing interface for ultrasensitive detection of volatile biomarkers of gastric cancer cells is a challenging task. Herein we reported to screen out novel volatile biomarkers associated with gastric cancer cells and develop a novel Au-Ag alloy composites-coated MWCNTs as sensing interface for ultrasensitive detection of volatile biomarkers. MGC-803 gastric cancer cells and GES-1 gastric mucous cells were cultured in serum-free media. The sample preparation approaches and HS-SPME conditions were optimized for screening volatile biomarkers. Volatiles emitted from the headspace of the cells/medium culture were identified using GC-MS. The Au-Ag nanoparticles-coated multiwalled carbon nanotubes were prepared as a sensing interface for detection of volatile biomarkers. Results showed that eight different volatile metabolites were screened out between MGC-803 cells and GES-1 cells. Two compounds such as 3-octanone and butanone were specifically present in the headspace of the MGC-803 cells. Three volatiles such as 4-isopropoxybutanol, nonanol and 4-butoxy 1-butanol coexisted in the headspace of both the MGC-803 cells and the GES-1 cells, their concentrations in the headspace of the GES-1cells were markedly higher than those in the MGC-803 cells, three volatiles such as formic acid propyl ester, 1.4-butanediol and 2, 6, 11-trimethyl dodecane solely existed in the headspace of the GES-1 cells. The nanocomposites of MWNTs loaded with Au-Ag nanoparticles were prepared as a electrochemical sensing interface for detection of two volatile biomarkers, cyclic voltammetry studies showed that the fabricated sensor could detect 3-octanone in the range of 0~0.0025% (v/v) and with a detection limitation of 0.3 ppb, could detect butanone in the range of 0 ~ 0.055% (v/v), and with a detection limitation of 0.5 ppb, and exhibited good selectivity. The novel electrochemical biosensor combined with volatile biomarkers of gastric cancer owns great potential in applications such as early diagnosis and the prognosis of gastric cancer in near future.

Keywords: Au-Ag nanoparticles; cyclic voltammetry; electrochemical sensor.; gastric cancer cells; multi-wall carbon nanotubes; volatile organic compounds.

Figure 1

The patterns from the chromatogram of VOCs from MGC-803 gastric cancer cells that were influenced by: (A) headspace extraction time; (B) MGC-803 cells cultured with and without Parafilm.

Figure 2

Comparison of VOCs chromatograms from the headspace of the MGC-803 cells, the GES-1 cells and media culture: (A) the chromatograms with a retention time 8~13 min; (B) the chromatograms with a retention time 17~20 min.

Figure 3

Characterization of MWNTs covered with Au-Ag nanoparticles: (A) TEM image; (B) SEM image; (C) HR-TEM image of Au-Ag nanoparticles on the surface of MWNTs; (D) the corresponding EDX spectra of MWNTs/Au-Ag nanoparticles.

Figure 4

(A) Cyclic voltammograms of MWNTs/Au-Ag/GCE, MWNTs/GCE, MWNTs/Ag/GCE, MWNTs/Au/GCE and bare GCE in 0.1 M KCl solution. (B) Cyclic voltammograms of MWNTs/Au-Ag/GCE in 0.1 M KCl solution with various scan rates (from a to g: 20,40,60,80,100,150 and 200, respectively). The inset is the linear plot between the anodic peak current and the scan rate.

Figure 5

(A): The cyclic voltammograms of MWNTs/Au-Ag/GCE were exposed to different concentrations of butanone (from a to h: 0, 0.05, 0.1, 0.15, 0.25, 0.35, 0.45 and 0.55 ppm, respectively). The inset shows a line plot of the peak current (I_p) against concentration of butanone. (B): The cyclic voltammograms of MWNTs/Au-Ag/GCE were exposed to different concentrations of 3-octanone (from a to f: 0, 0.05, 0.1, 0.15, 0.2 and 0.25 ppm, respectively). The inset shows a line plot of the peak current (I_p) against concentration of 3-octanone. All the potentials are given versus SCE.

Figure 6

Cyclic voltammograms of MWNTs/Au-Ag/GCE was exposed to the head space of cell-free medium, MGC-803 gastric cancer cells, and GES-1 gastric mucosa cells.