Mei Qiu Yan

Zhejiang University, Hangzhou, Zhejiang Sheng, China

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Publications (4)22.99 Total impact

  • Li Yan Qiu, Mei Qiu Yan
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    ABSTRACT: By changing the molar ratio of hydrophilic and hydrophobic segments, a series of novel amphiphilic graft polyphosphazenes (PEG/EtTrp-PPPs) was synthesized via thermal ring-opening polymerization and a subsequent two-step substitution reaction of hydrophilic methoxyl polyethylene glycol (MPEG) and hydrophobic ethyl tryptophan (EtTrp). (1)H-Nuclear magnetic resonance and Fourier transform infrared studies validated the expected synthesis of copolymers. The copolymer composition was also confirmed by UV-visible spectrophotometry. The molar ratio of the segment PEG to group EtTrp was 1.33:0.67, 1.01:0.99 and 0.78:1.22, respectively. Micellization behavior of PEG/EtTrp-PPPs in an aqueous phase was characterized by fluorescence technique, dynamic light scattering and transmission electron microscopy. The critical micelle concentration (CMC) of the graft copolymer in aqueous solution was 0.158, 0.033 and 0.020gl(-1), which decreased as the hydrophobic content in amphiphilic copolymers increased. Doxorubicin (DOX) was physically loaded into micelles prepared by an O/W emulsion method with a drug loading content increasing with DOX feeding. In vitro release of DOX from micelles can be accelerated in weak acidic solution. The results of cytotoxicity study using an MTT assay method with HeLa cell showed that amphiphilic graft polyphosphazenes were biocompatible while DOX-loaded micelles achieved comparable cytotoxicity with that of free DOX. In summary, these novel amphiphilic copolymers exhibited potential to be used as injectable drug carriers for tumor treatment.
    Acta biomaterialia 03/2009; 5(6):2132-41. · 5.68 Impact Factor
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    ABSTRACT: Preparation, in vitro and in vivo evaluation of indomethacin-loaded polymeric micelles based on amphiphilic polyphosphazene. Amphiphilic polyphosphazenes (PNIPAAm/EAB-PPPs) with poly (N-isopropylacrylamide) (PNIPAAm) and ethyl 4-aminobenzoate (EAB) as side groups were synthesized through thermal ring-opening polymerization and subsequent substitution reactions. Indomethacin (IND) loaded polymeric micelles based on PNIPAAm/EAB-PPPs were prepared by dialysis procedure. In vitro IND release kinetics was investigated in 0.1 M PBS (pH 7.4), while in vivo pharmacokinetics was performed in Sprague-Dawley rats. In vivo pharmacodynamic study was carried out based on two animal models, i.e. carrageenan-induced acute paw edema and complete Freund's adjuvant (CFA) induced ankle arthritis model. Drug loading capacity of micelles based on this type of amphiphilic copolymers was mainly determined by copolymer composition and the chemical structure of drug. In addition to the compatibility between drug and micellar core, hydrogen bonding interaction between drug and hydrophilic corona may significantly influence drug loading as well. In vitro drug release in PBS suggested that there was no significant difference in release rate between micelles based on copolymers with various EAB content. Compared with the rats administered with free IND aqueous solution, IND concentration in rats' plasma showed a prolonged maintenance in experimental group treated with IND-loaded polymeric micelles. In vivo pharmacodynamic study indicated that sustained therapeutic efficacy could be achieved through topical injection of the aqueous solution of IND-loaded micelles. Local delivery of IND can avoid the severe gastrointestinal stimulation, which was frequently associated with oral administration as evidenced by ulceration evaluation. The promising results of current preliminary study suggest that this type of amphiphilic copolymers could be used as injectable drug carriers for hydrophobic drugs.
    Pharmaceutical Research 11/2007; 24(10):1944-53. · 4.74 Impact Factor
  • Macromolecular Rapid Communications 03/2007; 28(6):710 - 717. · 4.93 Impact Factor
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    ABSTRACT: The effects of copolymer composition, drug structure and initial drug feed on drug loading of polymeric micelles based on amphiphilic polyphosphazenes were investigated. It was found that the drug loading capacity of micelles based on this type of amphiphilic copolymers was mainly determined by copolymer composition and the chemical structure of drug. In addition to the compatibility between drug and micellar core, hydrogen bonding interaction between drug and hydrophilic corona may significantly influence drug loading as well. In vitro drug release in 0.1 M PBS (pH 7.4) suggested that indomethacin (IND) in the micelles was released through Fickian diffusion, and no significant difference in release rate was observed for micelles based on copolymers with various EtTrp content. Compared with in vitro IND release profile, in vivo pharmacokinetic study after subcutaneous administration provides a more sustained release behavior. Additionally, in comparison with free drug solution at the same dose, IND concentration in rat plasma showed a prolonged retention when the drug was delivered through polymeric micelles. In vivo pharmacodynamic study based on both carrageenan-induced acute and complete Freund's adjuvant-induced adjuvant arthritis model indicated that sustained therapeutic efficacy could be achieved through intraarticular injection of IND-loaded micelles. Most importantly, local delivery of IND can avoid the severe gastrointestinal stimulation, which was frequently associated with oral administration.
    Journal of Controlled Release 01/2007; 116(3):322-9. · 7.63 Impact Factor