• 技术与应用 •

### 多材料3D打印技术制作用于毛细管电泳的非接触电导/激光诱导荧光二合一检测池

1. 1.桂林电子科技大学生命与环境科学学院, 广西 桂林 541004
2.品创检测(广西)有限公司, 广西 桂林 541004
• 收稿日期:2021-02-22 出版日期:2021-08-08 发布日期:2021-06-29
• 通讯作者: 张敏
• 作者简介:*Tel:(0773)2305125,E-mail: zhangmin@guet.edu.cn.
• 基金资助:
国家自然科学基金(21966012);国家自然科学基金(21705028);广西自然科学基金重点项目(2017GXNSFDA198043);广西八桂青年学者项目

### Multimaterial 3D-printed contactless conductivity/laser-induced fluorescence dual-detection cell for capillary electrophoresis

ZHANG Piwang1, YANG Liye1, LIU Qiang1, LU Shangui2, LIANG Ying1, ZHANG Min1,*()

1. 1. School of Life and Environmental Sciences, Guilin University of Electronic Technology, Guilin 541004, China
2. Pinchuang Testing (Guangxi) Corporation, Guilin 541004, China
• Received:2021-02-22 Online:2021-08-08 Published:2021-06-29
• Contact: ZHANG Min
• Supported by:
National Natural Science Foundation of China(21966012);National Natural Science Foundation of China(21705028);Guangxi Natural Science Foundation(2017GXNSFDA198043);Guangxi Bagui Young Scholar Program

Abstract:

Dual detection, which simultaneously employs two complementary detection methods, is a useful approach to enhance the selectivity and sensitivity of capillary electrophoresis (CE). Through dual detection, multiple classes of analytes with different structural and chemical characteristics can be sensitively detected using a single CE method. In addition, the comigrating peaks can be distinguished by comparing the signal outputs of two detectors with different selectivities. Typically, dual detection is achieved by coupling two detectors in series along a capillary. However, in this approach, it is inconvenient to evaluate the signal outputs of the two detectors. The two detectors present differences in their corresponding effective capillary lengths and dead volumes of the detection cell. Therefore, detectors that combine two or three detection methods in a single detection point are proposed to address this issue.
In this work, to fabricate a combined detector in a simple and low-cost manner, multimaterial 3D printing technology is employed. A two-in-one detection cell that combines capacitively coupled contactless conductivity detection (C4D) and confocal laser-induced fluorescence (LIF) detection was fabricated by 3D printing functional materials. In 3D printing, conductive composite polylactic acid (PLA, Proto-pasta) filaments and normal nonconductive PLA filaments were employed. The conductive material was used to build a C4D shielding layer that was electrically grounded. The nonconductive PLA was used as an electrical insulator placed between the shielding layer and C4D electrodes, which were two stainless-steel tubes (0.4 mm i.d. and 5 mm length). To embed the electrodes into the nonconductive material, a “print-pause-print” approach was applied. After building two chambers for housing electrodes using nonconductive PLA, the 3D printing was paused, following which the two electrodes were manually installed. Printing was then resumed, and the remaining part was built. The two electrodes were 2 mm apart, and the gap between them was filled with a conductive material for shielding to eliminate stray capacitance. A through-hole (1 mm i.d.) was placed between the middle conductive shielding layer for LIF detection. The size of the detection cell was 60 mm×29 mm×7.2 mm. The cell was screwed onto an XYZ stage to precisely align the light path of LIF detection, which was realized using a TriSep TM-2100LIF detector equipped with a 473 nm laser. C4D detection was achieved using a TraceDec detector equipped with a ChipCE adaptor. The two-in-one detector was coupled with a lab-made CE system that had a flow-through injection interface.
Use of the detection cell allows the simultaneous detection of inorganic cations and fluorescein isothiocyanate (FITC)-labeled amino acids. The C4D excitation frequency and buffer concentration were then optimized. A mixture of 10 mmol/L 3-(N-morpholino)propanesulfonic acid (MOPS) and 10 mmol/L bis(2-hydroxyethyl)amino-tris(hydroxymethyl)methane (Bis-Tris) was selected as the background electrolyte as a compromise of C4D signal-to-noise ratio (S/N) and separation efficiencies of amino acids. The C4D excitation frequency was set to 77 kHz with S/N=233±8 for 200 μmol/L Na +. The baseline separation of Na+, K+, Li+, FITC, fluorescein, histidine (His), lysine (Lys), tryptophan (Trp), phenylalanine (Phe), alanine (Ala), and glycine (Gly) was achieved with a 25 μm i.d.×365 μm o.d.×45 cm (35 cm effective length) capillary and -10 kV separation voltage. The limits of detection (LODs) of C 4D for Na+, K+, and Li+were 2.2, 2.0, and 2.6 μmol/L, respectively. The LODs of LIF for fluorescein and FITC were 7.6 and 1.7 nmol/L, respectively. The relative standard deviations (RSDs) of the two detection methods were within the range of 0.3%-4.5% (n=3). The r 2 of the calibration curves was ≥0.9904. Thus, 3D printing technology is a simple and low-cost approach to implement complex designs, including those that are difficult to fabricate by traditional “workshop” technologies.