title: [Preparation and release efficiency of polylactic acid nanoparticle].
abstract: OBJECTIVE
  As a new drug delivery carrier, medical nanoparticle (NP) appears to be very promising and are widely studied. Compare with microparticle, nanoparticle possesses several advantages, such as ultramicroscopic size, could be ingested by the cells after crossing the tissue matrix, and can penetrate the arterial wall and cross the blood-brain barrier. This study was to prepare polylactic acid (PLA) nanoparticle, and observe its morphology, diameter, structure, surface elements, and ability of in vitro drug release.
  
  
  METHODS
  The biodegradable PLA was used as the carrier, and 5-fluorouracil (5-FU) was used as the model drug. 5-FU-PLA nanoparticle (5-FU-PLA-NP) was prepared by matrix and ultrasound emulsification. Morphology of 5-FU-PLA-NP was observed under scanning electron microscope; its surface elements were detected by X ray photoelectron spectroscopyû its drug loading (DL), embedding ratio (ER), and ability of in vitro drug release were assessed by ultraviolet spectroscopy.
  
  
  RESULTS
  The nanoparticle was uniformly spherical with average diameter of (191+/-17) nm, DL of 15.2%, and ER of 45.6%. The nanoparticle showed sustained release character in the experiment of in vitro drug release: the cumulative drug release rate in analog body fluid was 94.3% at the 10th day.
  
  
  CONCLUSIONS
  PLA-NP may serve as a carrier of 5-FU, and can change the pharmacokinetics of 5-FU, slower down drug release; 5-FU-PLA-NP can be prepared as intravenous injection, and may prolong the in vivo circulation time of 5-FU, so as to play more efficient antitumor effects.
authors.affiliation: Department of Gastroenterology, The Second Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, P. R. China. huangkaih@21cn.com
authors.forename: Kai-Hong
authors.initials: KH
authors.lastname: Huang
authors.forename: Zhao-Hua
authors.initials: ZH
authors.lastname: Zhu
authors.forename: Jian-Hua
authors.initials: JH
authors.lastname: Liu
authors.forename: Qi-Kui
authors.initials: QK
authors.lastname: Chen
authors.forename: Xiao-Yan
authors.initials: XY
authors.lastname: Liu
authors.forename: Jin
authors.initials: J
authors.lastname: Chang
mesh_terms: D000964:Antimetabolites, Antineoplastic / Q000008:administration & dosage*; D003692:Delayed-Action Preparations; D004337:Drug Carriers; D016503:Drug Delivery Systems; D005472:Fluorouracil / Q000008:administration & dosage*; D019344:Lactic Acid / Q000008:administration & dosage*; D053758:Nanoparticles; D010316:Particle Size; D011091:Polyesters; D011108:Polymers / Q000008:administration & dosage*
chemical_list: D000964:Antimetabolites, Antineoplastic; D003692:Delayed-Action Preparations; D004337:Drug Carriers; D011091:Polyesters; D011108:Polymers; D019344:Lactic Acid; C033616:poly(lactide); D005472:Fluorouracil