Investigating Monoliths (Vinyl Azlactone-co-Ethylene Dimethacrylate) as a Support for Enzymes and Drugs, for Proteomics and Drug-Target Studies

Mixed-mode column allows simple direct coupling with immobilized enzymatic reactor for on-line protein digestion

Liquid chromatography coupled with mass spectrometry is widely used in the field of proteomic analysis after off-line protein digestion. On-line digestion with chromatographic column connected in a series with immobilized enzymatic reactor is not often used approach. In this work we investigated the impact of chromatographic conditions on the protein digestion efficiency. The investigation of trypsin reactor activity was performed by on-line digestion of N-α-benzoyl-L-arginine 4-nitroanilide hydrochloride (BAPNA), followed by separation of the digests on the mixed-mode column. Two trypsin column reactors with the different trypsin coverage on the bridged ethylene hybrid particles were evaluated. To ensure optimal trypsin activity, the separation temperature was set at 37.0 °C and the pH of the mobile phase buffer was maintained at 8.5. The on-line digestion itself ongoing during the initial state of gradient was carried out at a low flow rate using a mobile phase that was free of organic modifiers. Proteins such as cytochrome C, enolase, and myoglobin were successfully digested on-line without prior reduction or alkylation, and the resulting peptides were separated using a mixed-mode column. Additionally, proteins that contain multiple cysteines, such as α-lactalbumin, albumin, β-lactoglobulin A, and conalbumin, were also successfully digested on-line (after reduction and alkylation). Moreover, trypsin immobilized enzymatic reactors were utilized for over 300 injections without any noticeable loss of digestion activity.

Microfluidic Immobilized Enzymatic Reactors for Proteomic Analyses—Recent Developments and Trends (2017–2021)

Given the strong interdisciplinary nature of microfluidic immobilized enzyme reactor (μ-IMER) technology, several branches of science contribute to its successful implementation. A combination of physical, chemical knowledge and engineering skills is often required. The development and application of μ-IMERs in the proteomic community are experiencing increasing importance due to their attractive features of enzyme reusability, shorter digestion times, the ability to handle minute volumes of sample and the prospect of on-line integration into analytical workflows. The aim of this review is to give an account of the current (2017–2021) trends regarding the preparation of microdevices, immobilization strategies, and IMER configurations. The different aspects of microfabrication (designs, fabrication technologies and detectors) and enzyme immobilization (empty and packed channels, and monolithic supports) are surveyed focusing on μ-IMERs developed for proteomic analysis. Based on the advantages and limitations of the published approaches and the different applications, a probable perspective is given.

Flow-through enzymatic reactors using polymer monoliths: From motivation to application

The application of monolithic materials as carriers for enzymes has rapidly expanded to the realization of flow-through analysis and bioconversion processes. This expansion is partly attributed to the absence from diffusion limitation in many monoliths-based enzyme reactors. Particularly, the relatively ease of introducing functional groups renders polymer monoliths attractive as enzyme carriers. After summarizing the motivation to develop enzymatic reactors using polymer monoliths, this review reports the most recent applications of such reactors. Besides, the present review focuses on the crucial characteristics of polymer monoliths affecting the immobilization of enzymes and the processing parameters dictating the performance of the resulting enzymatic reactors. This review is intended to provide a guideline for designing and applying flow-through enzymatic reactors using polymer monoliths.