Enzyme Immobilized Magnetic Nanoparticles for In-Line Capillary Electrophoresis and Drug Biotransformation Studies: Application to Paracetamol

Application of Capillary Electrophoresis with Laser-Induced Fluorescence to Immunoassays and Enzyme Assays

Capillary electrophoresis using laser-induced fluorescence detection (CE-LIF) is one of the most sensitive separation tools among electrical separation methods. The use of CE-LIF in immunoassays and enzyme assays has gained a reputation in recent years for its high detection sensitivity, short analysis time, and accurate quantification. Immunoassays are bioassay platforms that rely on binding reactions between an antigen (analyte) and a specific antibody. Enzyme assays measure enzymatic activity through quantitative analysis of substrates and products by the reaction of enzymes in purified enzyme or cell systems. These two category analyses play an important role in the context of biopharmaceutical analysis, clinical therapy, drug discovery, and diagnosis analysis. This review discusses the expanding portfolio of immune and enzyme assays using CE-LIF and focuses on the advantages and disadvantages of these methods over the ten years of existing technology since 2008.

An improved design to capture magnetic microparticles for capillary electrophoresis based immobilized microenzyme reactors

In this paper, we demonstrate the effectiveness of a new 3D printed magnet holder that enables capture of magnetic microparticles in commercially available capillary electrophoresis equipment with a liquid or air based coolant system. The design as well as the method to capture magnetic microparticles inside the capillary are discussed. This setup was tested at temperature and pH values suitable for performing enzymatic reactions. To demonstrate its applicability in CE- immobilized microenzyme reactors (IMER) development, human flavin-containing monooxygenase 3 and bovine serum albumin were immobilized on amino functionalized magnetic microparticles using glutaraldehyde. These microparticles were subsequently used to perform in-line capillary electrophoresis with clozapine as a model substrate. This setup could be used further to establish CE-IMERs of other drug metabolic enzymes in a commercially available liquid based capillary coolant system. The CE-IMER setup was successful, although a subsequent decrease in enzyme activity was observed on repeated runs.

Hepatocyte-based flow analytical bioreactor for online xenobiotics metabolism bioprediction

The research for new in vitro screening tools for predictive metabolic profiling of drug candidates is of major interest in the pharmaceutical field. The main motivation is to avoid late rejection in drug development and to deliver safer drugs to the market. Thanks to the superparamagnetic properties of iron oxide nanoparticles, a flow bioreactor has been developed which is able to perform xenobiotic metabolism studies. The selected cell line (HepaRG) maintained its metabolic competencies once iron oxide nanoparticles were internalized. Based on magnetically trapped cells in a homemade immobilization chamber, through which a flow of circulating phase was injected to transport nutrients and/or the studied xenobiotic, off-line and online (when coupled to a high-performance liquid chromatography chain) metabolic assays were developed using diclofenac as a reference compound. The diclofenac demonstrated a similar metabolization profile chromatogram, both with the newly developed setup and with the control situation. Highly versatile, this pioneering and innovative instrumental design paves the way for a new approach in predictive metabolism studies.

Nanomaterials for sample pretreatment prior to capillary electrophoretic analysis

Nanomaterials are, in analytical science, used for a broad range of purposes, covering the area of sample pretreatment as well as separation, detection and identification of target molecules.

Utilization of magnetic nanobeads for analyzing haptoglobin in human plasma as a marker of Alzheimer's disease by capillary electrophoretic immunoassay with laser-induced fluorescence detection

Alzheimer's disease (AD) is a neurodegenerative disorder resulting from an impaired cholinergic function with loss of cognitive activity in the brain. Haptoglobin is a useful biomarker for AD analysis. Compared to the conventional enzyme-linked immunosorbent assay for haptoglobin analysis, the proposed immunoassay procedure reduces sample analysis time by approximately 55 min. Therefore, immunoassay was coupled with capillary electrophoresis (CE) to determine haptoglobin concentrations indirectly by using magnetic nanobeads (MBs) as a support and laser-induced fluorescence detection. In human plasma sample, the haptoglobin was immobilized on the MBs and reacted with the purified anti-haptoglobin antibody. The optimum separation time for the analyte was shorter than 6 min at 25 °C with a fused-silica capillary column of 40.2 cm × 50 μm ID (effective length 30 cm) and a run buffer containing 25 mM phosphate (pH 8.0) with 0.01% poly(ethylene oxide) (PEO). When using Atto 495 NHS ester as an internal standard (IS) (250.0 ng mL(-1)), the linear range of the proposed method for indirect determination of haptoglobin was 0.2-3.0 mg mL(-1). The method was further used to monitor the course of AD in patients with behavioral and psychological symptoms of dementia (BPSD).