The remarkable enhancement of photo-stability and antioxidant protection of lutein coupled with carbon-dot.

Lutein is a carotenoid that is beneficial to human health. However, its low stability and bioavailability have limited its application in the pharmaceutical and food industries. Herein, lutein has been successfully modified with carbon-dots (CDs) via a simple and mild solvent-ultrasonic method at room temperature. The synthesized lutein/CDs composites (LCs) showed 3.4 times higher photostability than the pristine lutein under UV irradiation, and 3.5 times higher than that under visible light, and the retention rate of lutein in the air rose from 3.6 % to 68 % over 25 days. Meanwhile, the antioxidant capacity of lutein has been improved by 6.4 times. Based on the photoluminescence (PL) measurements, a possible mechanism for the enhanced photostability and antioxidant ability of LCs has been proposed. The work provides a simple but effective approach to enhancing the stability and antioxidant capacity of lutein, and is expected to extend its application in food and biomedical fields.