title: Improved biological effects of uniconazole using porous hollow silica nanoparticles as carriers.
abstract: BACKGROUND
  The aim of this work is to prepare a controlled-release formulation of uniconazole using porous hollow silica nanoparticles (PHSNs) as carrier, and to investigate the biological effects on rice growth.
  
  
  RESULTS
  PHSNs with a shell thickness of ~15 nm and a particle size of 80-100 nm were synthesised through a sol-gel route using nanosized calcium carbonate particles as templates. Simple immersing (SI) and supercritical fluid drug loading (SFDL) technologies were employed to load uniconazole into PHSNs with loading efficiencies of ~22 and ~26% respectively. The prepared uniconazole-loaded PHSNs (UCZ-PHSNs) by SI and SFDL both demonstrated sustained release properties, and the latter showed better controlled release ability with a slower release rate. Compared with free uniconazole, UCZ-PHSNs exhibited a weaker growth retardation effect in the early stage but more significant retardation ability in later stages for agar-cultured rice seedlings. For the rice that grew in clay, UCZ-PHSNs demonstrated a weaker plant height retardation effect than free uniconazole at the early jointing stage by foliar spraying, but exhibited a stronger retardation capacity than free uniconazole by being applied into soil before seedling transplantation.
  
  
  CONCLUSIONS
  The results indicated that the prepared UCZ-PHSNs possessed good controlled-release properties and had improved retardation effects on rice growth. It is recommended that UCZ-PHSNs be applied into soil before seedling transplantation rather than administered by foliar spraying at the early jointing stage.
authors: Engineering Research Centre of Plant Growth Regulators, Ministry of Education, College of Agronomy and Biotechnology, China Agricultural University, Beijing, PR China.
authors: Wei-Ming
authors: WM
authors: Tan
authors: Ning
authors: N
authors: Hou
authors: Sen
authors: S
authors: Pang
authors: Xiao-Feng
authors: XF
authors: Zhu
authors: Zhao-Hu
authors: ZH
authors: Li
authors: Li-Xiong
authors: LX
authors: Wen
authors: Liu-Sheng
authors: LS
authors: Duan
mesh_terms: D004337:Drug Carriers / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry*; D012275:Oryza / Q000187:drug effects / Q000254:growth & development; D010316:Particle Size; D010937:Plant Growth Regulators / Q000737:chemistry / Q000494:pharmacology*; D016062:Porosity; D012822:Silicon Dioxide / Q000737:chemistry*; D014230:Triazoles / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D004337:Drug Carriers; D010937:Plant Growth Regulators; D014230:Triazoles; D012822:Silicon Dioxide; C092705:uniconazole