Microcapsules; Azur B; DNA Amplification Detector; Melting Dispersion Cooling Method; Multiple Emulsion
Microcapsules containing the aqueous solution of Azur B of a water soluble dye were prepared with the melting dispersion cooling method and applied to the amplification detector of plant DNA. Paraffin wax with melting temperature of 75°C was used as the shell material. In the experiment, the aqueous solution (W) of Azur B as the core material was dispersed in the melted paraffin wax (O) to form the (W/O) emulsion and then, the (W/O) emulsion was dispersed in the silicon oil (O’) as the continuous phase to form the (W/O)/O’ emulsion at 85°C. After formation of the (W/O)/O’ emulsion, the microcapsules were prepared by cooling the (W/O)/O’ emulsion to 50°C. The microcapsules were prepared by changing the concentration of oil soluble surfactant in the (W/O) emulsion and the volume of the (W/O) emulsion in the (W/O)/O’ emulsion. The microencapsulation efficiency increased with the concentration of oil soluble surfactant and finally became 100% under the optimum conditions. Furthermore, the microcapsules were melted down at temperature of 85°C to reveal the sharp thermal responsibility and to release the aqueous solution of Azur B. As a result, it was found that the microcapsules were able to be applied to the amplification detector of plant DNA by utilizing the reaction between DNA and Azur B.
Microcapsules; Azur B; DNA Amplification Detector; Melting Dispersion Cooling Method; Multiple Emulsion
Microcapsules have various functions such as protection and isolation of core material, instantaneous and controlled release of core material, surface modification of core material, solidification of liquid and gaseous core materials, responsibility to various stimuli and so on [
Thus, the microcapsules have prepared mainly with both the chemical and the physicochemical methods and have been applied in the various fields such as cosmetics [
Stimuli-responsibility of their functions is the most important one, because the core materials are able to be released according to the stimulus species such as mechanical pressure [
Azur B of a water soluble dye is known to singularly react with plant DNA and to be applied to detect plant DNA, namely, to utilize as the Amplification Detector of plant DNA [
If the aqueous solution of Azur B could be microencapsulated with the shell material to reveal the thermal responsibility and these microcapsules could be dispersed stably in the aqueous solution of plant DNA, the concentration of DNA in the aqueous solution should be able to be detected instantaneously by destroying the microcapsules due to heating and releasing the aqueous solution of Azur B without direct contact to the detecting system. For this purpose, it is necessary to prepare the microcapsules by the shell material with the sharp responsibility to the desired temperature and the perfect water proof.
In this study, paraffin wax is selected as the shell material to satisfy these demands and the melting dispersion cooling method is adopted to prepare the microcapsules [
In general, the (W/O)/W emulsion as the multiple emulsion has been utilized for preparing the microcapsules containing the aqueous solution [
The purposes of this study are to develop the method for preparing the microcapsules containing the aqueous solution of water soluble dye, to investigate the effects of the preparation conditions on the microencapsulation efficiency, the content of aqueous solution and the thermal responsibility and to apply to the DNA amplification detector.
The materials used in this study are as follows. Paraffin wax (O) with melting temperature of 75˚C was used as the shell material. Azur B of a water soluble dye with molecular structure as shown in
The silicon oil (KF400, Shinetsu Chemical Co, Ltd) was used as the continuous phase (O’). As the oil soluble surfactants, Poem PR-100 and Poem J0021 (Riken Vitamin Co, Ltd) were added in the melted shell material to form the (W/O) dispersion and in the continuous phase to form the (W/O)/O’ emulsion, respectively.
When the (W/O)/O’ emulsion was cooled down to 50˚C, the microcapsules were prepared due to solidification of paraffin wax of the shell material. In this preparation process, the volume of aqueous solution of Azur B in paraffin wax (hold up in the (W/O) emulsion) and the concentration (Cs) of oil soluble surfactant (PoemPR- 100) in the (W/O) emulsion were changed stepwise. The experimental conditions are shown in