Rice bran nanofiber composites for stabilization of phytase.

This study explores the potential application of rice bran (agro waste) to nano-encapsulate phytase, which is a thermally unstable biologically active enzyme. Rice bran was converted to nanofibers (20-50 nm in diameter) using electrospinning. After optimizing the pH, viscosity, voltage and the distance between electrodes for electrospinning, phytase enzyme was encapsulated and the fibers were cross-linked using sodium tripolyphosphate. Thermal stability of phytase enzyme was improved by 90 °C when they are encapsulated and cross-linked with sodium tripolyphosphate. The activity of the phytase enzyme was monitored at different temperatures. The activity of the pure enzyme was lost at 80 °C while the enzyme encapsulated into nanofibers demonstrated the activity up to 170 °C. This study opens up many opportunities for nanotechnology value addition to many waste materials and also to improve the properties of a range of biomaterials through a sustainable approach.

Urea-Hydroxyapatite Nanohybrids for Slow Release of Nitrogen.

While slow release of chemicals has been widely applied for drug delivery, little work has been done on using this general nanotechnology-based principle for delivering nutrients to crops. In developing countries, the cost of fertilizers can be significant and is often the limiting factor for food supply. Thus, it is important to develop technologies that minimize the cost of fertilizers through efficient and targeted delivery. Urea is a rich source of nitrogen and therefore a commonly used fertilizer. We focus our work on the synthesis of environmentally benign nanoparticles carrying urea as the crop nutrient that can be released in a programmed manner for use as a nanofertilizer. In this study, the high solubility of urea molecules has been reduced by incorporating it into a matrix of hydroxyapatite nanoparticles. Hydroxyapatite nanoparticles have been selected due to their excellent biocompatibility while acting as a rich phosphorus source. In addition, the high surface area offered by nanoparticles allows binding of a large amount of urea molecules. The method reported here is simple and scalable, allowing the synthesis of a urea-modified hydroxyapatite nanohybrid as fertilizer having a ratio of urea to hydroxyapatite of 6:1 by weight. Specifically, a nanohybrid suspension was synthesized by in situ coating of hydroxyapatite with urea at the nanoscale. In addition to the stabilization imparted due to the high surface area to volume ratio of the nanoparticles, supplementary stabilization leading to high loading of urea was provided by flash drying the suspension to obtain a solid nanohybrid. This nanohybrid with a nitrogen weight of 40% provides a platform for its slow release. Its potential application in agriculture to maintain yield and reduce the amount of urea used is demonstrated.