High-performance microchip electrophoresis separations of preterm birth biomarkers using 3D printed microfluidic devices

Abstract

We employed digital light processing-stereolithography 3D printing to create microfluidic devices with different designs for microchip electrophoresis (µCE). Short or long straight channel, and two- or four-turn serpentine channel microfluidic devices with separation channel lengths of 1.3, 3.1, 3.0, and 4.7 cm, respectively, all with a cross injector design, were fabricated. We measured current as a function of time and voltage to determine a separation time window and conditions for the onset of Joule heating in these designs. Separations in these devices were evaluated by performing µCE and measuring theoretical plate counts for electric field strengths near and above the onset of Joule heating, with fluorescently labeled glycine and phenylalanine as model analytes. We further demonstrated µCE of peptides and proteins related to preterm birth risk, showing increased peak capacity and resolution compared to previous results with 3D printed microdevices. These results mark an important step forward in the use of 3D printed microfluidic devices for rapid bioanalysis by µCE.

Keywords: 3D printing; Microchip electrophoresis; Microfabrication; Microfluidics; Preterm birth biomarkers.

Fig. 1.

3D printed μCE devices. CAD design files of (A) short, (B) long, (C) two-turn serpentine, and (D) four-turn serpentine CE microdevices. Channels (green), reservoirs (purple). Gnd, ground; SW, sample waste; S, sample; HV, high voltage; D1–D5, detection points (DP). Photographs of (E) short, (F) long, (G) two-turn serpentine, and (H) four-turn serpentine microchip CE devices. (I) Zoomed view of a serpentine turn in (G) with a 170 μm tapered length, TL.

Fig. 2.

μCE in short 3D printed microchips. Separation of 40 nM G and 60 nM F in 50 mM HEPES pH 8 at various injection/separation electric fields. A) 350/770 V/cm B) 390/920 V/cm C) 420/1150 V/cm.

Fig. 3.

μCE in long 3D printed microchips with 300/480 V/cm injection/separation fields. Separation of 40 nM G and 75 nM F in 50 mM HEPES pH 8, with detection point 1 mm from the end of the channel.

Fig. 4.

μCE in 3D printed two-turn serpentine microchips. Separation at 330 V/cm of 40 nM G and 60 nM F in 50 mM HEPES pH 8, with detection points at A) D1, B) D2, C) D3, D) D4, and E) D5.

Fig. 5.

μCE of 40 nM G and 60 nM F in 50 mM HEPES pH 8, at 430 V/cm in a 3D printed four-turn serpentine device.

Fig. 6.

μCE of PTB biomarkers in (A) short 3D printed microchip with injection/separation fields of 350/770 V/cm; (B) long 3D printed microchip with injection/separation fields of 300/480 V/cm (1.7 nM P1, 34 nM P3, 8.4 nM CRF, 5 nM Fer, and 17 nM LF); (C) 2-turn serpentine device at 350/330 V/cm; D) 4-turn serpentine device at 350/430 V/cm (0.85 nM P1, 17 nM P3, 4.2 nM CRF, 2.5 nM Fer, 8.3 nM LF, and 25 nM TNF).