title: Urea-Hydroxyapatite Nanohybrids for Slow Release of Nitrogen.
abstract: 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.
authors.affiliation: Nanotechnology and Science Park, Center for Excellence in Nanotechnology, Sri Lanka Institute of Nanotechnology (SLINTEC) , Mahenawatta, Pitipana, Homagama CO 10206, Sri Lanka.|Department of Chemistry, University of Sri Jayewardenepura , Nugegoda 10250, Sri Lanka.
authors.forename: Nilwala
authors.initials: N
authors.lastname: Kottegoda
authors.affiliation: Nanotechnology and Science Park, Center for Excellence in Nanotechnology, Sri Lanka Institute of Nanotechnology (SLINTEC) , Mahenawatta, Pitipana, Homagama CO 10206, Sri Lanka.
authors.forename: Chanaka
authors.initials: C
authors.lastname: Sandaruwan
authors.affiliation: Nanotechnology and Science Park, Center for Excellence in Nanotechnology, Sri Lanka Institute of Nanotechnology (SLINTEC) , Mahenawatta, Pitipana, Homagama CO 10206, Sri Lanka.
authors.forename: Gayan
authors.initials: G
authors.lastname: Priyadarshana
authors.affiliation: Nanotechnology and Science Park, Center for Excellence in Nanotechnology, Sri Lanka Institute of Nanotechnology (SLINTEC) , Mahenawatta, Pitipana, Homagama CO 10206, Sri Lanka.
authors.forename: Asitha
authors.initials: A
authors.lastname: Siriwardhana
authors.affiliation: Nanotechnology and Science Park, Center for Excellence in Nanotechnology, Sri Lanka Institute of Nanotechnology (SLINTEC) , Mahenawatta, Pitipana, Homagama CO 10206, Sri Lanka.
authors.forename: Upendra A
authors.initials: UA
authors.lastname: Rathnayake
authors.affiliation: Nanotechnology and Science Park, Center for Excellence in Nanotechnology, Sri Lanka Institute of Nanotechnology (SLINTEC) , Mahenawatta, Pitipana, Homagama CO 10206, Sri Lanka.
authors.forename: Danushka Madushanka
authors.initials: DM
authors.lastname: Berugoda Arachchige
authors.affiliation: Nanotechnology and Science Park, Center for Excellence in Nanotechnology, Sri Lanka Institute of Nanotechnology (SLINTEC) , Mahenawatta, Pitipana, Homagama CO 10206, Sri Lanka.|Faculty of Science and Technology, University of Uva Wellassa , Badulla 90000, Sri Lanka.
authors.forename: Asurusinghe R
authors.initials: AR
authors.lastname: Kumarasinghe
authors.affiliation: Nanotechnology and Science Park, Center for Excellence in Nanotechnology, Sri Lanka Institute of Nanotechnology (SLINTEC) , Mahenawatta, Pitipana, Homagama CO 10206, Sri Lanka.
authors.forename: Damayanthi
authors.initials: D
authors.lastname: Dahanayake
authors.affiliation: Nanotechnology and Science Park, Center for Excellence in Nanotechnology, Sri Lanka Institute of Nanotechnology (SLINTEC) , Mahenawatta, Pitipana, Homagama CO 10206, Sri Lanka.|Department of Chemistry, University of Peradeniya , Peradeniya 20400, Sri Lanka.
authors.forename: Veranja
authors.initials: V
authors.lastname: Karunaratne
authors.affiliation: Nanotechnology and Science Park, Center for Excellence in Nanotechnology, Sri Lanka Institute of Nanotechnology (SLINTEC) , Mahenawatta, Pitipana, Homagama CO 10206, Sri Lanka.|Department of Engineering, University of Cambridge , Trumpington Street, Cambridge CB2 1PZ, United Kingdom.
authors.forename: Gehan A J
authors.identifier: 0000-0002-8614-2864
authors.initials: GA
authors.lastname: Amaratunga
keywords: nanoparticles; nitrogen fertilizer; slow release; urea-modified hydroxyapatite nanohybrid