Screening Aptamer of Apo-transferrin via Capillary Electrophoresis-Systematic Evolution of Ligands by Exponential Enrichment and Environmental Factors Analysis

Three-step evolutionary enhanced capillary electrophoresis-SELEX for aptamer selection of exosome vesicles

As various disease biomarkers, drugs/biomolecules carriers and physiological function regulator, exosomes play significant roles in various physiological and pathological process. Thus, the purification and detection of some exosome are of great significance, which make it necessary for the development of the recognition elements. Aptamers with high affinity and specificity exhibited well in the above areas. In this work, a new three-step evolutionary enhanced strategy based on capillary electrophoresis (CE)-SELEX was proposed for effective aptamer selection of exosome vesicles for the first time. Natural killer cells (NK) exosome was used as the model target. And the aptamer could be obtained in five round CE selection within three steps evolution including precise nucleic acid sequence convergence (with NK exosome specific proteins as targets in round 1st and 3rd), affinity evolution (with NK exosome as target in round 2nd and 4th) and specific evolution (negative selection in round 5th). Arising from the compatibility of CE-SELEX for exosome vesicles aptamer selection, and the proposed strategy, aptamer against NK exosome had been selected with good affinity (KD value of 27.6 nM) and excellent specificity. The as proposed CE-SELEX strategy paves a novel way for recognition element selection of exosome vesicles.

Induction of binding sites for RecA aptamers by differentiated-competition capillary Electrophoresis-SELEX

The binding site-oriented SELEX strategy is an effective way to promote the functional evolution of aptamers. Here we report a novel aptamer screening strategy (Differentiated-competition Capillary Electrophoresis-SELEX), which enables candidate aptamers to be directionally induced to bind to different active sites of RecA. In this strategy, we introduce two competing binding factors into the "binding - dissociation" dynamic equilibrium system of RecA and ssDNA libraries. Due to the completely different binding mechanism of the competitive factor and the ssDNA library, it exerts different interference on the binding of RecA and the ssDNA library, which directed the binding site of aptamer candidates during the SELEX process. Multifunctional aptamers with high affinity and specificity were found to inhibit RecA activity by binding to different active sites. In conclusion, the SELEX method developed in our current study have identified a variety of biologically functional aptamers with relatively well-defined binding sites that regulate RecA protein activity, which has potential applications and future prospects for accurate screening of biological functional aptamers.

[Annual review of capillary electrophoresis technology in 2020]

该文为2020年毛细管电泳(capillary electrophoresis, CE)技术年度回顾。归纳总结了以“capillary electrophoresis-mass spectrometry”或“capillary isoelectric focusing”或“micellar electrokinetic chromatography”或“capillary electrophoresis”为关键词在ISI Web of Science数据库中进行主题检索得到的2020年CE技术相关研究论文222篇,以及中文期刊《分析化学》和《色谱》中CE技术相关的研究论文37篇。对2020年影响因子(IF)≥5.0的Analytical Chemistry, Food Chemistry, Analytica Chimica Acta和Talanta等13本期刊的38篇文章报道的科研工作作了逐一介绍;对IF<5.0的期刊中CE技术报道较为集中的Journal of Chromatography A和Electrophoresis两本分析化学类期刊发表40篇文章中的代表性内容作了综合介绍;对重要的中文期刊《分析化学》出版的“核酸适配体专刊”和《色谱》出版的2期CE技术专刊所收录的37篇文章中的工作作了总体介绍。总体来说,2020年CE技术发展趋势仍以毛细管电泳-质谱(CE-MS)的新方法和新应用最为突出,主要集中在CE-MS与电化学检测、固相萃取以及多种毛细管电泳模式的联用方面,CE-MS接口相关的报道较前几年有所减少;常规CE技术则以胶束电动毛细管色谱(MEKC)在复杂样本分析、浓缩富集应用为主,尤其在食品和药品等复杂基质样本分析方面的报道较为集中;此外,我国CE相关领域专家学者的科研成果涵盖了CE在生命科学、临床医学、医药研发、环境科学、天然产物、食品分析等领域的应用,代表了国内CE科研应用水平和现状。

A fluorescent aptasensor based on berberine for ultrasensitive detection of bisphenol A in tap water

The residues of bisphenol A (BPA) in food packaging and water systems have a potential impact on human health; therefore, its analysis and detection have drawn scientists' attention. In this work, based on the change in fluorescence intensity resulting from the conformational switch of a berberine/BPA-aptamer system in the presence and absence of BPA, an ultra-sensitive fluorescence aptasensing system is proposed, in which BPA-aptamer is employed as the identification unit and berberine as the fluorescent probe. Various factors affecting the detection of BPA, including the concentration of the fluorescent probe, BPA-aptamer, BPA, pH, system stability time and other experimental conditions, were investigated in detail. Under the optimal experimental conditions, the fluorescence intensity of the sensing system of berberine/BPA-aptamer exhibited a good linear correlation with the BPA concentration in the range of 0-1300 μM with a LOD of 32 nM. The proposed fluorescent sensing system also exhibited excellent recoveries of 92.4-102.3% in tap water samples and showed good application prospects for the analysis and detection of BPA.

Selection and characterization of an ssDNA aptamer against thyroglobulin

Thyroglobulin (Tg) is a significant biomarker for the diagnose and postoperative monitoring of differentiated thyroid cancer, and its recognition is urgent due to the rising prevalence. In this study, an ssDNA aptamer against Tg was obtained by capillary electrophoresis-systematic evolution of ligands via exponential enrichment (CE-SELEX). Under the optimized conditions, the sub-library was enriched well through two selection rounds. After high-throughput sequencing, eight candidate sequences were picked out and their affinities towards Tg were observed not in accordance with the order of their frequencies, whereas sequence homology played a significant role in binding affinity. The high-affinity sequence Seq.T-2 with a dissociation constant (K_d) of 3.18 μM was finally selected as the aptamer, and its affinity was confirmed qualitatively by gold nanoparticles colorimetric and quantitatively by thin film interferometry (K_d, 4.51 nM). Besides, molecular docking and dynamics simulation were performed for their binding sites prediction and affinity confirmation. Furthermore, the aptamer was applied for Tg detection, which delivered a detection limit of 5.0 nM as well as with good selectivity, and showed a good linear relationship within a wide range of 10 nM-6.4 μM of Tg spiked into the serum matrix. This study first reported Tg's aptamer which also exhibited the potential in real applications.

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.