A novel optical/electrochemical biosensor for real time measurement of physiological effect of astaxanthin on algal photoprotection

An optical/amperometric biosensor based on algal cells immobilized in calcium alginate gel was developed. Various Chlamydomonas reinhardtii strains mutated at the level of photosynthetic D1 protein were used as biomediators to quantify the capacity of the carotenoid xanthophylls to protect the photosynthetic apparatus from photoinhibition. The highly sensitive/selective biosensor was used for studies on cell physiology aimed to determine the antioxidant and light filtering effects of the xanthophyll astaxanthin. The biosensor was proved to be suitable for the determination of the exogenous supplied astaxanthin, showing in a short time a reliable response with a detection limit of 3 ?M. This technique revealed the photoprotective effect of astaxanthin-enriched extracts of Haematococcus pluvialis in algal cells. The results suggest that in algae astaxanthin exploits both filtering and antioxidant effects at different light intensities. This bioinspired approach can provide new insights into biological, biomedical, environmental and agricultural research applications and nutraceutical studies.