Microfluidic Device Directly Fabricated on Screen-Printed Electrodes for Ultrasensitive Electrochemical Sensing of PSA

Abstract

How to fabricate scale low-cost microfluidic device for detection of biomarkers owns a great requirement. Herein, it is for the first time reported that a new microfluidic device based on bonding polydimethylsiloxane microfluidic channels onto the substrate of a screen-printed electrode with coating glass solution was fabricated for electrochemical sensing of prostate-specific antigen (PSA). Compared to traditional microfabrication processes, this method is simple, fast, low cost, and also suitable for mass production. The prepared screen-printed electrode-based microfluidic device (CASPE-MFD) was used for the detection of the PSA in human serum. The prepared CASPE-MFD had a detection limit of 0.84 pg/mL (25.8 fM) and a good linearity with PSA concentration ranging from 0.001 to 10 ng/mL, which showed a great promise platform toward the development of miniaturized, low-cost electrochemical microfluidic device for use in human health, environmental monitoring, and other applications.

Keywords: Detection; Electrochemical sensor; Microfluidic devices; PSA; Screen-printed electrode.

Fig. 1

a Fabrication process for the PDMS microfluidic channels patterned by SU-8 photolithography. b Fabrication process for the commercially available screen-printed electrode-based microfluidic device. The CASPE-MFD comprises PDMS microfluidic channels, two printed gold electrodes as the working and counter electrodes, and a printed silver electrode as the pseudo-reference electrode. c A commercially available screen-printed electrode-based microfluidic device

Fig. 2

a Screen-printed photoelectrode used to take fluorescence images. b Fluorescence image of CASPE-MFD. We use a photoelectrode as a model fluorescence image to demonstrate that the working area is full with dyes and has no bubbles in the CASPE-MFD. c Partial enlarged drawing of the fluorescence image

Fig. 3

a Cyclic voltammograms of 0.5 mM ferrocene carboxylic acid in 0.1 M KCl aqueous solution (pH 7.0) in CASPE-MFD at different scan rates (ascending along the y-axis): 10, 25, 50, 80, 100, 150, 200, 250, 300, and 350 mV/s. b Calibration plots of the anodic (i_pa) and cathodic peak current (i_pc) vs the square scan rate. The two lines represent a linear curve with regression equation, respectively: Y (i_pa) = 0.9932X − 0.2563 (R² = 0.9996, n = 8); Y (i_pc) = − 0.9384X − 0.1774 (R² = 0.9996, n = 8)

Fig. 4

a The whole detection device. The syringe pump was used to inject solution into the CASPE-MFD, and the electrochemical workstation was used to detect the electrochemical signals. b The CASPE-MFD used to detect PSA. Immunomagnetic bead-conjugated anti-PSA antibody was injected with solutions through inlet, and a magnet was used to capture the magnetic beads. c Schematic of the CASPE-MFD in detection of PSA antigen. Immunomagnetic bead-conjugated anti-PSA antibody was immobilized on the working electrode using a magnet. PSA antigen was injected into the CASPE-MFD and conjugated with the anti-PSA antibody. HRP-modified anti-PSA antibody was then conjugated with PSA antigen. Chronoamperometry was used to detect the electrochemical signals that hydroquinone and hydrogen peroxide produced

Fig. 5

a Chronoamperometric curves for various concentrations of PSA antigen (ascending along the y-axis): 0, 0.001, 0.01, 0.1, 1, and 10 ng/mL in pH 7.4 PBS buffer containing 4.5 mM hydroquinone and 0.1 mM H₂O₂ solution in CASPE-MFD at − 2.0 mV vs silver pseudo-reference electrode. b The linear relationship between peak current and PSA antigen concentration in the CASPE-MFDs in pH 7.4 PBS buffer (blue line) and in human serum (red line). The linear regression equation of the blue line is Y = 14.87 + 3.927 × X (R² = 0.9985, n = 8), and the linear regression equation of the red line is Y = 14.15 + 3.622 × X (R² = 0.9986, n = 8). c Square wave voltammograms for various concentrations of PSA antigen in pH 7.4 PBS buffer containing 4.5 mM hydroquinone and 0.1 mM H₂O₂ solution in CASPE-MFD (ascending along the y-axis): 0, 0.001, 0.01, 0.1, 1, and 10 ng/mL, respectively. d The corresponding linear relationship of different concentrations of PSA antigen. The linear regression equation is Y = 34.53 + 9.246 × X (R² = 0.9884, n = 8)