Study On The Fluorescence Properties And Adsorption Property To Tetracycline Antibiotics Of Bee Pollen Sporopollenins

Sporopollenin is the main component of the outer walls of spores and pollens (i.e. sporopollen). It’s highly resistant to temperature, high pressure as well as chemical attack. Sporopollenins from different categories of plant pollen have a similar chemical structure. In this study, we extracted sporopollenin from bee pollen of Camellia oleifera Abel, Nelumbo nucifera, Rosa rugosa, Rhus chinensis Mill, and Brassica campestris L. and characterized on their morphology and structure.Depending on the nature of sporopollenins’ fluorescence properties, we inspected their light and chemical stability by fluorescence spectrophotometer. In addition, we also studied on the adsorption characteristics of tetracycline antibiotics onto the 5 kinds of sporopollenins. The results are as follows:(1) Preparation and characterization of bee pollen sporopollenins:The sporopollenins were extracted by refluxing in strong base and acid sequentially in order to degrade the intine and intracellular material, leaving a round and single layered outer wall, that is sporopollenin. Optical microscopy and scanning electron microscopy observation shows that the sporopollenins become wrinkled and of a smaller size compared to the pollen grains, and their colporates and ornamentation are more clearer.(2) The spectral scanning of sporopollenin:including UV-visible spectrum scanning(UV-Vis) and Fourier Transform Infra-Red spectrum scanning(FT-IR). The maximum absorption peaks of the UV-Vis spectrum of sporopollenins situate in the wavelength of 400 nm or more, which indicated that the electrons of sporopollenin molecules in the ground state occurrence π→π*,n→π*electronic transition, proofing that there are unsaturated bonds and conjugated system in the molecules. This conclusion were proved by the FT-IR spectra. The FT-IR spectra also told us that the sporopollenin is a polyester compound and there are hydroxyl, carboxyl, conjugated double bond and benzene ring in the molecule.(3) Fluorescence properties of sporopollenin:Sporopollenins exhibited yellow or yellow-green fluorescence with blue light(450nm-490nm) stimulating. Fluorescence excitation and emission spectra showed that the optimal excitation and emission wavelength are 460 nm and 555±5 nm respectively.(4) Light and chemical stability of sporopollenins fluorescence:Sporopollenins were irradiated with excitation light at 460nm for 3 hours, results showed no significant difference of the sporopollenins with or without light irradiation. When added a certain amount of strong oxidizing agent of hydrogen peroxide or strong reducing agent of sodium borohydride, sporopollenins exhibited relatively stable chemical resistance contrast to the common fluorescent agents.(5) Adsorption study of tetracycline antibiotics to sporopollenins:Tetracyclines can be absorbed by sporopollenins. There were differences among the adsorption capacity of one tetracycline onto different sporopollenins, the adsorption capacity of tetracycline antibiotics onto sporopollenins of Rosa rugosa and Rhus chinensis Mill. are higher than that onto sporopollenins of Camellia oleifera Abel, Nelumbo nucifera and Brassica campestris L. Additionally, there were also differences among the adsorption capacity of different tetracyclines onto the same sporopollenin. The adsorption mechanism of tetracycline antibiotics onto sporopollenins included physical and chemical adsorption.