Methods and devices for in situ determination of a vitamin-D synthesizing amount of natural and artificial UV irradiation
A matrix with a biologically active substance is exposed to UV radiation. The biologically active substance is selected to initiate photoconversions originating vitamin D synthesis. An optical parameter of the biologically active substance is being changed under UV irradiation. Change of the optical parameter is measured, thus measuring the amount of UV radiation that has caused the vitamin D synthesis occurred through photoconversion. Measuring occurs by way of a dosimeter.
1. A method for determination in situ of vitamin-D synthesizing amount of natural and artificial ultraviolet (UV) radiation, comprising:
embedding a bioactive substance into a material adapted to inhibit competitive channels of intermediate photoproduct photoconversion
exposing the bioactive substance adapted to exhibit photochemical transformations that initiate vitamin D synthesis in nature to an UV radiation the vitamin-D synthesizing amount of which is to be determined;
measuring change of absorbance of the bioactive substance upon exposition to the UV radiation; and
correlating the measured change of the absorbance to a vitamin-D synthesizing amount, wherein the vitamin-D synthesizing amount corresponding to the measured change of the absorbance is the vitamin-D synthesizing amount corresponding to the UV radiation to which the bioactive substance has been exposed.
2. The method according to claim 1 , wherein the bioactive substance is provitamin D.
3. The method according to claim 2 , wherein the provitamin D is ergosterol (provitamin D2).
4. The method according to claim 2 , wherein the provitamin D is 7-dehydrocholesterol (provitamin D3).
5. The method according to claim 1 , wherein the material is resistant to ultraviolet radiation and transparent in the spectral range of absorption of the bioactive substance.
6. The method according to claim 5 , wherein the material is selected from the group consisting of a porous silica film, a polymer film, a liquid crystalline layer, and a polymer dispersed liquid crystal (PDLC).
7. The method according to claim 6 , wherein the material is porous silica film entrapping the bioactive substance and wherein pore size of the porous silica film is optimized to suppress conformational mobility of the bioactive substance and photoisomers of the bioactive substance.
8. The method according to claim 7 , wherein the bioactive substance is 7-DHC solubilized within 6-cyclodextrin introduced within the porous silica film via adsorption.
9. The method according to claim 6 , wherein the polymer film is polyvinyl alcohol (PV
A) polymer and wherein embedding occurs by:
dissolving PVA in water to obtain a solution of polyvinyl alcohol;
introducing an ethanol solution of the bioactive substance;
mixing the solution of polyvinyl alcohol with the ethanol solution of the bioactive substance; and drying.
10. The method according to claim 1 , wherein the absorbance is in the spectral region corresponding to the one of the absorption bands of the bioactive substance.
11. The method according to claim 10 , wherein the absorption band is an absorption band with a maximum near to 280 nm.
12. The method according to claim 1 , wherein the absorbance is absorbance A and wherein measuring the change ΔA occurs by measuring a difference change ΔA=A t −A O between absorbance A t upon exposition to UV radiation and absorbance A o prior to exposition to UV radiation.
13. The method of claim 1 , wherein correlating the measured change of the absorbance parameter to a vitamin-D synthesizing amount occurs through comparison between a first calibration curve showing absorbance in function of UV radiation of the bioactive substance embedded in a material resistant to ultraviolet radiation and transparent in the spectral range of absorption of the bioactive substance and a second calibration curve showing synthesizing amount of the bioactive substance in function of time of the bioactive substance without said material and establishing, upon said comparison a curve showing said absorbance in function of said synthesizing amount.
14. A personal biodosimeter for determination in situ of vitamin-D-synthetic dose of natural and/or artificial ultraviolet (UV) radiation, comprising:
a UV source;
a sensing unit comprising a bioactive substance embedded in a matrix structure, the sensing unit adapted to be irradiated by the UV source and/or natural and/or artificial UV radiation, wherein the matrix is selected from the croup consisting of porous silica film, polymer film, polymer dispersed liquid crystal (PDLC), and a film containing the bioactive substance;
a photodetector located downstream the sensing unit, the photodetector sensitive to UV radiation and adapted to detect an output of the sensing unit; and
a processor connected with the photodetector and adapted to process the output of the photodetector, the output of the photodetector being indicative of a change in absorbance of the sensing unit upon UV irradiation from the UV source and/or natural and/or artificial UV radiation.
15. The personal biodosimeter of claim 14 , further comprising an analog-to-digital converter to convert the output of the photodetector before processing by the processor.
16. The personal biodosimeter of claim 14 , further comprising a display panel connected with the processor.
17. The biodosimeter according to claim 14 , wherein the UV source irradiates in a narrow spectral range corresponding to an absorption band of the bioactive substance.
18. The biodosimeter according to claim 14 , wherein the bioactive substance is provitamin D2 or D3.
19. The biodosimeter according to claim 14 , wherein the UV source irradiates at a wavelength of about 280 nm.
20. The biodosimeter according to claim 14 , wherein the matrix with bioactive substance is replaceable.
21. A personal biodosimeter for determination in situ of vitamin-D-synthetic dose of natural and/or artificial ultraviolet (UV) radiation, comprising:
a UV source;
a sensing unit comprising a bioactive substance embedded in a matrix structure, the sensing unit adapted to be irradiated by the UV source and/or natural and/or artificial UV radiation, wherein the matrix is a material creating preferential conditions for a single previtamin D photoconversion;
a photodetector located downstream the sensing unit, the photodetector sensitive to UV radiation and adapted to detect an output of the sensing unit; and
a processor connected with the photodetector and adapted to process the output of the photodetector, the output of the photodetector being indicative of a change in absorbance of the sensing unit upon UV irradiation from the UV source and/or natural and/or artificial UV radiation.