title: Investigation of glucose-modified liposomes using polyethylene glycols with different chain lengths as the linkers for brain targeting.
abstract: BACKGROUND
  An intimidating challenge to transporting drugs into the brain parenchyma is the presence of the blood-brain barrier (BBB). Glucose is an essential nutritional substance for brain function sustenance, which cannot be synthesized by the brain. Its transport primarily depends on the glucose transporters on the brain capillary endothelial cells. In this paper, the brain-targeted properties of glucose-modified liposomes using polyethylene glycols with different chain lengths as the linkers were compared and evaluated to establish an optimized drug-delivery system.
  
  
  METHODS
  Coumarin 6-loaded liposomes (GLU200-LIP, GLU400-LIP, GLU1000-LIP, and GLU2000-LIP) composed of phospholipids and glucose-derived cholesterols were prepared by thin-film dispersion-ultrasound method. The BBB model in vitro was developed to evaluate the transendothelial ability of the different liposomes crossing the BBB. The biodistribution of liposomes in the mice brains was identified by in vivo and ex vivo nearinfrared fluorescence imaging and confocal laser scanning microscopy and further analyzed quantitatively by high-performance liquid chromatography.
  
  
  RESULTS
  Glucose-derived cholesterols were synthesized and identified, and coumarin 6-loaded liposomes were prepared successfully. The particle sizes of the four types of glucose-modified liposomes were around or smaller than 100 nm with a polydispersity index less than 0.300. GLU400-LIP, GLU1000-LIP, and GLU2000-LIP achieved higher cumulative cleared volumes on BBB model in vitro after 6 hours compared with GLU200-LIP (P < 0.05) and were significantly higher than that of the conventional liposome (P < 0.001). The qualitative and quantitative biodistribution results in the mice showed that the accumulation of GLU1000-LIP in the brain was the highest among all the groups (P < 0.01 versus LIP).
  
  
  CONCLUSIONS
  The data indicated that GLU400-LIP, GLU1000-LIP, and GLU2000-LIP all possess the potential of brain targeting, among which GLU1000-LIP, as a promising drug-delivery system, exhibited the strongest brain delivery capacity.
authors.affiliation: Key Laboratory of Drug Targeting and Drug Delivery Systems, West China School of Pharmacy, Sichuan University, No. 17 Block 3 Southern Renmin Road, Chengdu, People's Republic of China.
authors.forename: Fulan
authors.initials: F
authors.lastname: Xie
authors.forename: Nian
authors.initials: N
authors.lastname: Yao
authors.forename: Yao
authors.initials: Y
authors.lastname: Qin
authors.forename: Qianyu
authors.initials: Q
authors.lastname: Zhang
authors.forename: Huali
authors.initials: H
authors.lastname: Chen
authors.forename: Mingqing
authors.initials: M
authors.lastname: Yuan
authors.forename: Jie
authors.initials: J
authors.lastname: Tang
authors.forename: Xiankun
authors.initials: X
authors.lastname: Li
authors.forename: Wei
authors.initials: W
authors.lastname: Fan
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhang
authors.forename: Yong
authors.initials: Y
authors.lastname: Wu
authors.forename: Li
authors.initials: L
authors.lastname: Hai
authors.forename: Qin
authors.initials: Q
authors.lastname: He
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001812:Blood-Brain Barrier / Q000378:metabolism; D001921:Brain / Q000378:metabolism*; D001923:Brain Chemistry; D003374:Coumarins / Q000737:chemistry* / Q000493:pharmacokinetics; D016503:Drug Delivery Systems / Q000379:methods*; D004355:Drug Stability; D005947:Glucose / Q000737:chemistry*; D008081:Liposomes / Q000737:chemistry; D051379:Mice; D011092:Polyethylene Glycols / Q000737:chemistry*; D019265:Spectroscopy, Near-Infrared; D013844:Thiazoles / Q000737:chemistry* / Q000493:pharmacokinetics; D014018:Tissue Distribution
chemical_list: D003374:Coumarins; D008081:Liposomes; D013844:Thiazoles; C517282:coumarin 6; D011092:Polyethylene Glycols; D005947:Glucose