Hollow pollen shells to enhance drug delivery.

Pollen grain and spore shells are natural microcapsules designed to protect the genetic material of the plant from external damage. The shell is made up of two layers, the inner layer (intine), made largely of cellulose, and the outer layer (exine), composed mainly of sporopollenin. The relative proportion of each varies according to the plant species. The structure of sporopollenin has not been fully characterised but different studies suggest the presence of conjugated phenols, which provide antioxidant properties to the microcapsule and UV (ultraviolet) protection to the material inside it. These microcapsule shells have many advantageous properties, such as homogeneity in size, resilience to both alkalis and acids, and the ability to withstand temperatures up to 250 °C. These hollow microcapsules have the ability to encapsulate and release actives in a controlled manner. Their mucoadhesion to intestinal tissues may contribute to the extended contact of the sporopollenin with the intestinal mucosa leading to an increased efficiency of delivery of nutraceuticals and drugs. The hollow microcapsules can be filled with a solution of the active or active in a liquid form by simply mixing both together, and in some cases operating a vacuum. The active payload can be released in the human body depending on pressure on the microcapsule, solubility and/or pH factors. Active release can be controlled by adding a coating on the shell, or co-encapsulation with the active inside the shell.

DSC study of sucrose melting.

An early endothermic peak at approximately 150 degrees C was observed for crystalline sucrose by differential scanning calorimetry. The enthalpy at this temperature was found to vary with recrystallised sucrose from different sources. The addition of mineral salts to recrystallisation solutions decreased the enthalpy of the peak at around 150 degrees C, whereas the absence of salts increased it. The presence of organic solvents and polysaccharides in solution had a minor effect compared to the inorganic impurities. The peak was also depleted by increasing the amount of stirring and temperature at which recrystallisation was performed.