UV-biosensor for visual indication of vitamin D synthesis

Excessive UV doses have adverse effects on human health, but proper amount of UV is beneficial for people and is essential in the natural production of vitamin D-# in skin. Most of broadband UV-radiometers that have an output in sunburn units are incapable to record correctly the vitamin D synthetic capacity of sunlight because of the difference between the CIE erythema and 'Vitamin D synthesis' action spectra. The liquid-crystalline UV sensor based on provitamin D photoconversions has been developed for direct observation of vitamin D synthesis under UV irradiation. UV-induced transformation of provitamin D in cholesteric liquid-crystalline matrix is accompanied by the change of cholesteric pitch value in the LC cell. The developed UV biosensor makes possible both instrumental and visual monitoring of the vitamin D synthetic capacity of sunlight and/or artificial UV source.