Capillary zone electrophoresis-based cytotoxicity analysis of Caco-2 cells

Capillary Electrophoresis Involving in High Efficiency Screening for Aptamers

Systematic evolution of ligands by exponential enrichment (SELEX) is a universal technology for aptamer' screening. Accurate and efficient screening methods and strategy design are the key to success. This review briefly summarizes capillary electrophoresis (CE) involving in the efficient screening for aptamers in our group since 2007, including the application of CE in pre-screening, screening and post-screening process, classification and screening strategies against different protein targets, multiple screening modes, and screening for multi-scale targets. Finally, combined with the current progresses of aptamer screening, some remaining issues are discussed and the development prospects are proposed.

A single-round selection of selective DNA aptamers for mammalian cells by polymer-enhanced capillary transient isotachophoresis

A single-round DNA aptamer selection for mammalian cells was successfully achieved for the first time using a capillary electrophoresis (CE)-based methodology called polymer-enhanced capillary transient isotachophoresis (PectI). The PectI separation yielded a single peak for the human lung cancer cell line (PC-9) complexed with DNA aptamer candidates, which was effectively separated from a free randomized DNA library peak, ensuring no contamination from free DNA in the PC-9-DNA aptamer complex fraction. The DNA aptamer candidates obtained after a single-round selection employing counter selection with HL-60 were proven to bind selectively and form kinetically stable complexes with PC-9 cells. Interestingly, most aptamer candidates showed high binding ability (K_d = 70-350 nM) with different extents of binding on the cell surface. These facts proved that a single-round selection for mammalian cells by PectI is feasible to obtain various types of aptamer candidates, which have high-affinity even for non-overexpressed but unique targets on the cell surface in addition to overexpressed targets.

Capillary electrophoresis strategy to monitor the released and remaining nitric oxide from the same single cell using a specially designed water-soluble fluorescent probe

Gasotransmitters including nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H2S) have attracted more and more attention in the past decades due to their unique signaling and functions. However, as a fundamental issue in the investigations of gasotransmitters, the cell membrane permeability and release behavior of them is controversial in reports because of the lack of an efficient approach to determine gasotransmitters released out of and remaining in the same cells simultaneously. To solve such problem, taking NO as representative, a robust and facile strategy has been reported based on a completely water-soluble fluorescent probe and a commercially available capillary electrophoresis system. A specially designed boron-dipyrromethene (BODIPY)-based fluorescent probe with two sulfonate groups, disodium 2,6-disulfonate-1,3,5,7-tetramethyl-8-(3',4'-diaminophenyl) difluoroboradiaza-s-indance (TMDSDAB), has been developed. As a turn-on fluorescent probe, TMDSDAB can react with NO promptly in aqueous media, and 540-fold enhancement of fluorescence is obtained. Using TMDSDAB, the trapping and quantification of NO released out of and remaining in the same single cell was achieved by capillary electrophoresis with laser-induced fluorescence detection. The limit of detection is 0.5 nM for NO. The proposed method has been applied to estimate the release behavior of single macrophages, and the results indicated that the cell membrane should be a barrier to NO diffusion.

Simultaneous determination of electrophoretic and dielectrophoretic mobilities of human red blood cells

Electrophoresis and dielectrophoresis of cells can reveal many distinct cellular properties but are often conducted separately. Herein a simultaneous strategy was proposed, and a simple method was established by making cells migrate through a cross channel under a micro video for real-time observation. The experiment can be performed within 0.044-1 s. In combination with digital calculation based on electromagnetic theory, the method was validated to be applicable to the determination of electrophoretic and dielectrophoretic mobilities, μEP and μDEP , of human blood erythrocytes, giving μEP = -(0.87 ± 0.16)× 10(-4) cm(2) ·V(-1) · s(-1) and μDEP = -(4.5 ± 1.3) × 10(-8) cm(4) ·V(-2) ·s(-1) by vector decomposition, or μEP = -(0.89 ± 0.14) × 10(-4) cm(2) ·V(-1) · s(-1) and μDEP = -(4.6 ±1.2) × 10(-8) cm(4) ·V(-2) · s(-1) by least squares fitting, all agreeing with published data. Hydrodynamic and EOFs were eliminated for better measurement. It was found that the location of cells had a serious impact on the measurement precision, and the upstream of the cross channel along the electric field was chosen for precise measurement. The method is also extendable to the study of other cells and particles.