Analysis of amino acids in cell culture supernatant using capillary electrophoresis with contactless conductivity detection

Selective measurement of valine, leucine, and isoleucine using corresponding aminoacyl-tRNA synthetases and application to paper-based analytical devices for colorimetric detection

BACKGROUND

Branched-chain amino acids (BCAAs) are vital for maintaining muscle performance and their measurement is critical for assessing nutritional status, health, and disease conditions. However, selective analysis of individual BCAAs remains challenging due to the limited selectivity of conventional enzymes. In this study, we explore the enzymatic detection of BCAAs (valine (Val), leucine (Leu), and isoleucine (Ile)) among 20 amino acids using their corresponding aminoacyl-tRNA synthetases (aaRSs) as recognition elements. Based on our findings, a paper-based analytical device (PAD) for Val, Leu, and Ile was developed using filtration paper.

RESULTS

The calibration curves, and selectivity of each aaRS were assessed using a microplate reader. Trinder's reagent was used as the colorimetric reaction following aaRS reaction. Additionally, Val, Leu, and Ile analysis was conducted on real food samples to evaluate practical applicability. Linear relationships were established for Val (2-75 μM; correlation coefficient: R2 = 0.959), Leu (2-50 μM; R2 = 0.984), and Ile (1-100 μM; R2 = 0.982), with detection limits of 18.5, 7.6, and 8.4 μM, respectively, using the microplate reader. Furthermore, PAD exhibited linear relationships for Val (7-80 μM; R2 = 0.978), Leu (9-80 μM; R2 = 0.956), and Ile (19-80 μM; R2 = 0.961), with detection limits of 2.2, 3.1, and 6.3 μM, respectively. The analysis was completed within 15 min.

SIGNIFICANCE

Trinder's reagent, a colorimetric reaction reagent, ensures ease of use and safety owing to its neutral pH. Furthermore, it facilitated the development of PAD and analysis of Val, Leu, and Ile. The findings of this study contribute to the advancement of robust biomedical devices precisely for amino acid analysis. High-resolution detection was accomplished using a USB camera and novel RGB value analysis equations.

Contactless Conductivity Detection for Capillary Electrophoresis-Developments From 2020 to 2024

The review covering the development of capillary electrophoresis with capacitively coupled contactless conductivity detection from 2020 to 2024 is the latest in a series going back to 2004. The article considers applications employing conventional capillaries and planar lab-on-chip devices as well as fundamental and technical developments of the detector and complete electrophoresis instrumentation.

Determination of amino acids and peptides without their pre-column derivatization by capillary electrophoresis with ultraviolet and contactless conductivity detection. An overview

This review provides an overview of recent works focusing on the determination of amino acids (AAs) and peptides using capillary electrophoresis with contactless conductivity detection and ultraviolet (UV) detection, which is the most widespread detection in capillary electromigration techniques, without pre-capillary derivatization. Available options for the UV detection of these analytes, such as indirect detection, complexation with transition metal ions, and in-capillary derivatization are described. Developments in the field of direct detection of UV-absorbing AAs and peptides as well as progress in chiral separation are described. A separate section is dedicated to using on-line sample preconcentration methods combined with capillary electrophoresis-UV.

Quantification of amino acids secreted by yeast cells by hydrophilic interaction liquid chromatography-tandem mass spectrometry

Monitoring the levels of amino acids (AAs) in biological cell cultures provides key information to understand the regulation of cell growth and metabolism. Saccharomyces cerevisiae can naturally excrete AAs, making accurate detection and determination of amino acid levels within the cultivation medium pivotal for gaining insights into this still poorly known process. Given that most AAs lack ultraviolet (UV) chromophores or fluorophores necessary for UV and fluorescence detection, derivatization is commonly utilized to enhance amino acid detectability via UV absorption. Unfortunately, this can lead to drawbacks such as derivative instability, labor intensiveness, and poor reproducibility. Hence, this study aimed to develop an accurate and stable hydrophilic interaction liquid chromatography-tandem mass spectrometry analytical method for the separation of all 20 AAs within a short 17-min run time. The method provides satisfactory linearity and sensitivity for all analytes. The method has been validated for intra- and inter-day precision, accuracy, recovery, matrix effect, and stability. It has been successfully applied to quantify 20 AAs in samples of yeast cultivation medium. This endeavor seeks to enhance our comprehension of amino acid profiles in the context of cell growth and metabolism within yeast cultivation media.

[Annual review of capillary electrophoresis technology in 2021]

This paper provides an annual review of capillary electrophoresis (CE) technology in 2021. A total of 291 research papers related to CE technology published in 2021 were retrieved from the ISI Web of Science using the keywords, "capillary electrophoresis-mass spectrometry" "capillary isoelectric focusing" "micellar electrokinetic chromatography", or "capillary electrophoresis" (not "capillary electrochromatography" "microchip" and "capillary monolithic column"). In addition, nine research papers related to CE technology in Chinese journals were reviewed: Chinese Journal of Chromatography and Chinese Journal of Analytical Chemistry. This review focused on seven papers published in Coordination Chemistry Reviews, Angewandte Chemie-International Edition, Nature Protocols, TrAC-Trends in Analytical Chemistry, and Signal Transduction and Targeted Therapy with impact factors (IFs) greater than 10.0, as well as 42 papers reported in Analytical Chemistry, Analytica Chimica Acta, Talanta, and Food Chemistry with IFs between 5.0 and 10.0. This review also provides a comprehensive overview of representative CE works in Journal of Chromatography A and Electrophoresis with IFs<5.0, as well as important Chinese journals, Chinese Journal of Chromatography and Chinese Journal of Analytical Chemistry. According to the IF, this paper introduces the representative work of CE-related papers to allow readers to quickly understand the important research progress of CE technology in the past year.