title: Improving thermal stability and efficacy of BCNU in treating glioma cells using PAA-functionalized graphene oxide.
abstract: BACKGROUND
  1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU), a commercial chemotherapeutic drug for treating malignant brain tumors, has poor thermal stability and a short half-life. Immobilization of BCNU on a nanocarrier might increase the thermal stability of BCNU and extend its half-life.
  
  
  METHODS
  Nanosized graphene oxide (GO) could be modified by polyacrylic acid (PAA) to improve the aqueous solubility and increase the cell penetration efficacy of the nanocarrier. PAA-GO intended as a drug carrier for BCNU was prepared and characterized in this study. The size and thickness of PAA-GO was investigated by transmission electron microscopy and atomic force microscopy, and the presence of PAA functional groups was confirmed by electron spectroscopy for chemical analysis and thermogravimetric analysis. BCNU was conjugated to PAA-GO by covalent binding for specific killing of cancer cells, which could also enhance the thermal stability of the drug.
  
  
  RESULTS
  Single layer PAA-GO (about 1.9 nm) with a lateral width as small as 36 nm was successfully prepared. The optimum drug immobilization condition was by reacting 0.5 mg PAA-GO with 0.4 mg BCNU, and the drug-loading capacity and residual drug activity were 198 μg BCNU/mg PAA-GO and 70%, respectively. This nanocarrier significantly prolonged the half-life of bound BCNU from 19 to 43 hours compared with free drug and showed efficient intracellular uptake by GL261 cancer cells. The in vitro anticancer efficacy of PAA-GO-BCNU was demonstrated by a 30% increase in DNA interstrand cross-linking and a 77% decrease in the IC(50) value toward GL261 compared with the same dosage of free drug.
  
  
  CONCLUSIONS
  Nanosized PAA-GO serves as an efficient BCNU nanocarrier by covalent binding. This nanocarrier will be a promising new vehicle for an advanced drug delivery system in cancer therapy.
authors.affiliation: Department of Chemical and Materials Engineering, Chang Gung University, Kwei-San, Taoyuan, Taiwan.
authors.forename: Yu-Jen
authors.initials: YJ
authors.lastname: Lu
authors.forename: Hung-Wei
authors.initials: HW
authors.lastname: Yang
authors.forename: Sheng-Che
authors.initials: SC
authors.lastname: Hung
authors.forename: Chiung-Yin
authors.initials: CY
authors.lastname: Huang
authors.forename: Shin-Ming
authors.initials: SM
authors.lastname: Li
authors.forename: Chen-Chi M
authors.initials: CC
authors.lastname: Ma
authors.forename: Pin-Yuan
authors.initials: PY
authors.lastname: Chen
authors.forename: Hong-Chieh
authors.initials: HC
authors.lastname: Tsai
authors.forename: Kuo-Chen
authors.initials: KC
authors.lastname: Wei
authors.forename: Jyh-Ping
authors.initials: JP
authors.lastname: Chen
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D000818:Animals; D018906:Antineoplastic Agents, Alkylating / Q000008:administration & dosage* / Q000493:pharmacokinetics; D002330:Carmustine / Q000008:administration & dosage* / Q000493:pharmacokinetics; D045744:Cell Line, Tumor; D004337:Drug Carriers / Q000737:chemistry; D016503:Drug Delivery Systems; D004355:Drug Stability; D004705:Endocytosis; D005910:Glioma / Q000188:drug therapy* / Q000378:metabolism / Q000648:ultrastructure; D006108:Graphite / Q000737:chemistry; D006207:Half-Life; D051379:Mice; D018625:Microscopy, Atomic Force; D046529:Microscopy, Electron, Transmission; D058726:Nanoconjugates / Q000737:chemistry / Q000648:ultrastructure; D050997:Nanomedicine; D013696:Temperature
chemical_list: D000180:Acrylic Resins; D018906:Antineoplastic Agents, Alkylating; D004337:Drug Carriers; D058726:Nanoconjugates; C006903:carbopol 940; D006108:Graphite; D002330:Carmustine