Microalgae amino acid extraction and analysis at nanomolar level using electroporation and capillary electrophoresis with laser-induced fluorescence detection.

Reine Nehmé,Carla Atieh,Slim Abdelkafi,Philippe Morin,Chantal Pichon,Fatma Elleuch,Syntia Fayad,Mona Tannoury,Agnès Chartier,Bérengère Claude

doi:10.1002/jssc.201601005

Abstract

Amino acids play a key role in food analysis, clinical diagnostics, and biochemical research. Capillary electrophoresis with laser-induced fluorescence detection was used for the analysis of several amino acids. Amino acid labeling with fluorescein isothiocyanate was conducted using microwave-assisted derivatization at 80°C (680 W) during only 150 s. Good electrophoretic resolution was obtained using a background electrolyte composed of sodium tetraborate buffer (100 mM; pH 9.4) and β-cyclodextrin (10 mM), and the limits of quantification were 3-30 nM. The developed capillary electrophoresis with laser-induced fluorescence method was used to analyze amino acids in Dunaliella salina green algae grown under different conditions. A simple extraction technique based on electroporation of the cell membrane was introduced. A home-made apparatus allowed the application of direct and alternating voltages across the electrochemical compartment containing a suspension of microalgae in distilled water at 2.5 g/L. A direct voltage of 12 V applied for 4 min gave the optimum extraction yield. Results were comparable to those obtained with accelerated-solvent extraction. The efficiency of electroporation in destroying microalgae membranes was shown by examining the algae surface morphology using scanning electron microscopy. Stress conditions were found to induce the production of amino acids in Dunaliella salina cells.

Highlights

Amino acids are organic compounds that exhibit a major role in many fields
CE–LIF was chosen for the analysis of amino acids extracted by electroporation from Dunaliella salina microalgae
The increase in the concentration of fluorescein isothiocyanate (FITC) induced an increase in signal magnitude of amino acid and of additional interfering signals

Summary

Introduction

Amino acids are organic compounds that exhibit a major role in many fields (nutrition, health, cosmetics, biochemistry, etc). Several cosmetic products have proved to bring flexibility, softness and elasticity to human skin due to their content in amino acids. Their level in stratum corneum which is the outermost layer of the epidermis and the protecting barrier of the skin is a potential marker of this organ health. DS microalga is known to be the best commercial source of natural β-carotene It can accumulate significant amounts of valuable chemicals such as carotenoids, lipids, vitamins and proteins. In regard to amino acid extraction from microalgae a new method based on low voltage (few V/cm, few mA) was developed. It was shown that electrically based disruption techniques such as pulsed electric field (PEF) (20 kV/cm, 1–4 ms) and high-voltage electrical discharge (HVED)

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