(321d) Detection of Beta Carotene and Lutein Using Electrochemical Impedance Spectroscopy

Carotenoids are biological pigment molecules that are often found in fruits, vegetables, and human tissue. Humans cannot synthesize carotenoids, but they can be accumulated through diet [1]. Carotenoids have been found to lower oxidative stress which can lead to a lower risk of disease and infections [2]. Lower carotenoid levels have also been correlated to patients with Alzheimer’s Disease, Parkinson’s Disease, and multiple types of cancer [3,4]. Although there is a reverse correlation between the concentration of carotenoids and risk of disease, there are still a lot of qualities of carotenoids that are unknown to scientists. An effective point-of-care, cheap, and sensitive carotenoid sensor would aid in showing causality in human patients using carotenoid levels as a potential screening biomarker.

Electrochemistry is a cost effective sensing paradigm while maintaining sensitivity [5]. Electrochemical impedance spectroscopy (EIS), an electrochemical method that measures the surface impedance when an alternating current is applied, is known to be an extremely sensitive surface technique. We investigated the use of EIS to correlate carotenoid solution concentration to glassy carbon surface interactions. Nanomolar levels of β-carotene and lutein were successfully detected using EIS in a solution with only analyte and in the presence of each other. Uniquely reported here will be the sensitivity and selectivity of β-carotene in the presence of lutein and the lutein in the presence of β-carotene. Surface-bound β-cyclodextrin was used to increase carotenoid detection sensitivity. β-cyclodextrin was chosen because of its ability to create host-guest complexes with hydrophobic molecules such as β-carotene and lutein. The sensitivity of carotenoid detection using β-cyclodextrin will be reported compared to unmodified electrodes. In conclusion, the significant progress we have made over the past year (i.e. detecting carotenoids in the presence of competing molecules and cyclodextrin surface modifications) will be reported and discussed.

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