title: Ultrasound, pH, and magnetically responsive crown-ether-coated core/shell nanoparticles as drug encapsulation and release systems.
abstract: Core@shell nanoparticles with superparamagnetic iron oxide core, mesoporous silica shell, and crown ether periphery were fabricated toward drug delivery and tumor cell imaging. By the concept of nanovalve based on supramolecular gatekeeper, stimuli-responsive drug delivery nanosystems Fe3O4@SiO2@meso-SiO2@crown ethers were synthesized by (i) modified solvothermal reaction; (ii) sol-gel reaction; and (iii) amide coupling reaction. The successful coupling of the dibenzo-crown ethers onto the mesoporous silica shell was confirmed by thermogravimetric analysis and Infrared spectroscopy. In this system, the "ON/OFF" switching of the gatekeeper supramolecules can be controlled by pH-sensitive intramolecular hydrogen bonding or electrostatic interaction (such as metal chelating). Biological evaluation of the nanoparticles renders them noncytotoxic and can be uptaken by L929 cells. In this work, the antitumor drug (doxorubicin) loading and release profiles which were studied by the UV/visible absorption spectroscopy. The mechanism involves the best-fit binding of crown ethers with cesium or sodium ions at different pH values with ultrasonic wave in phosphate buffered saline (PBS). Magnetic resonance imaging analysis of the particles reveals a high relaxivity, rendering them potentially useful theranostic agents.
authors: Department of Chemistry, Prince of Wales Hospital, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR, PR China.
authors: Siu-Fung
authors: SF
authors: Lee
authors: Xiao-Ming
authors: XM
authors: Zhu
authors: Yi-Xiang J
authors: YX
authors: Wang
authors: Shou-Hu
authors: SH
authors: Xuan
authors: Qihua
authors: Q
authors: You
authors: Wing-Hong
authors: WH
authors: Chan
authors: Chi-Hin
authors: CH
authors: Wong
authors: Feng
authors: F
authors: Wang
authors: Jimmy C
authors: JC
authors: Yu
authors: Christopher H K
authors: CH
authors: Cheng
authors: Ken Cham-Fai
authors: KC
authors: Leung
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry* / Q000494:pharmacology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D003692:Delayed-Action Preparations / Q000737:chemistry* / Q000494:pharmacology; D004317:Doxorubicin / Q000737:chemistry* / Q000494:pharmacology; D004337:Drug Carriers / Q000737:chemistry*; D004339:Drug Compounding; D016503:Drug Delivery Systems / Q000295:instrumentation / Q000379:methods*; D004986:Ether / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D058185:Magnetite Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D012822:Silicon Dioxide / Q000737:chemistry; D014465:Ultrasonics
chemical_list: D000970:Antineoplastic Agents; D003692:Delayed-Action Preparations; D004337:Drug Carriers; D058185:Magnetite Nanoparticles; D004986:Ether; D012822:Silicon Dioxide; D004317:Doxorubicin