Microfluidic immunosensor based on a graphene oxide functionalized double helix microfiber coupler for anti-Müllerian hormone detection

Abstract

A label-free microfluidic immunosensor based on the double helix microfiber coupler (DHMC) coated with graphene oxide (GO) was proposed for the specific detection of anti-Müllerian hormone (AMH). Two single-mode optical fibers were twisted in a parallel direction, the coning machine was used to fuse and taper them, and the high-sensitivity DHMC was obtained. To make a stable sensing environment, it was immobilized in a microfluidic chip. And then, the DHMC was modified by GO and bio-functionalized by the AMH monoclonal antibodies (anti-AMH MAbs) for the specific detection of AMH. The experimental results showed that the detection range of the immunosensor for AMH antigen solutions was 200 fg/mL∼50 µg/mL, the detection of limit (LOD) was ∼235.15 fg/mL, and the detection sensitivity and the dissociation coefficient were ∼3.518 nm/(log(mg/mL)) and ∼1.85 × 10 ^{- 12} M, respectively. The alpha fetoprotein (AFP), des-carboxy prothrombin (DCP), growth stimulation expressed gene 2 (ST2) and AMH serum were used to confirm the excellent specific and clinical properties of the immunosensor, showing that the proposed immunosensor was easy-made and can be potentially applied in the biosensing field.

Fig. 1.

Schematic diagram of the DHMC structure.

Fig. 2.

Schematic of fabrication of DHMC.

Fig. 3.

RI sensitivity of the DHMC. (a) transmission spectra in different RI solutions; (b) relationship between the wavelength shift and the RI.

Fig. 4.

Schematic illustration of functionalization process

Fig. 5.

Diagram of the microfluidic chip. (a) the encapsulation process; (b)prepared microfluidic chip.

Fig. 6.

Experimental setup for AMH detection

Fig. 7.

Analysis of biofunctionalization process. (a)spectrum response in-time during the fabrication of biosensor; (b) corresponding wavelength shift; (c) FESEM image of GO coated DHMC with 200 K times magnification; (d) energy spectrum of GO-coated DHMC.

Fig. 8.

AMH antigen detection experiment of the immunosensor. (a) Real-time wavelength shift response of DHMC in AMH antigen detection. (Inset: transmission spectral responses at 100 pg/mL); (b) Spectrum evolution with AMH antigen concentration

Fig. 9.

The relationship between the wavelength red shift of DHMC and the concentration of AMH antigen. (a) Langmuir curve fitting diagram; (b) detection sensitivity of DHMC

Fig. 10.

Experimental results of clinical and specific detection of DHMC. (a) The evolution spectrum; (b) Changes of wavelength shift.