title: Hyperbranched polymer-drug conjugates with high drug payload for enhanced cellular delivery.
abstract: OBJECTIVE
  To synthesize and evaluate hyperbranched polymer (HBP)-drug conjugates with high drug payload for enhanced cellular delivery.
  
  
  METHODS
  Polyol- and polyglycerol-ibuprofen conjugates with or without imaging agent fluorescein isothiocyanate (FITC) were synthesized using dicyclohexilcarbodiimide (DCC) as a coupling agent. Drug-polymer conjugates were characterized using 13C NMR, 1H NMR, and gel permeation chromatography (GPC). Stability of the drug-conjugates was studied using free drug release through a dialysis membrane. Cellular entry of FITC-labeled HBP conjugates was studied using fluorescence activated cell sorter (FACS), and cell supernatant was analyzed by UV-visible spectrophotometer. The intracellular localization of FITC-labeled conjugates in A549 lung epithelial cells was imaged using fluorescence microscopy. Anti-inflammatory activity of the HBP-ibuprofen conjugates was estimated in vitro by measuring the concentration of prostaglandin (PGE2) using an ELISA kit.
  
  
  RESULTS
  The average number of ibuprofen molecules conjugated per molecule of HBP was estimated to be 50 for polyol and 53 for polyglycerol. The HBP-drug conjugates did not release the drug up to 72 h in methanol, indicating the presence of stable ester bonds. Both the polymer-drug conjugates entered the cells rapidly. The conjugates were localized in the cell cytosol as evidenced by fluorescence microscopy. Within 30 min, the HBP-drug conjugates showed rapid suppression of PGE2 synthesis, whereas free ibuprofen did not show any activity. At later times, the conjugates showed comparable activity.
  
  
  CONCLUSIONS
  For the first time, we report HBP conjugates with a high drug payload. HBP-drug conjugates entered the cells rapidly and produced the desired pharmacological action. This study demonstrates that hyperbranched polyol and polyglycerol are promising nanovehicles for achieving enhanced cellular delivery of drugs.
authors.affiliation: Department of Chemical Engineering and Material Science, and Biomedical Engineering, Wayne State University, Detroit, Michigan 48202, USA.
authors.forename: Parag
authors.initials: P
authors.lastname: Kolhe
authors.forename: Jayant
authors.initials: J
authors.lastname: Khandare
authors.forename: Omathanu
authors.initials: O
authors.lastname: Pillai
authors.forename: Sujatha
authors.initials: S
authors.lastname: Kannan
authors.forename: Mary
authors.initials: M
authors.lastname: Lieh-Lai
authors.forename: Rangaramanujam
authors.initials: R
authors.lastname: Kannan
mesh_terms: D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D016503:Drug Delivery Systems / Q000379:methods*; D016650:Fluorescein-5-isothiocyanate / Q000008:administration & dosage / Q000493:pharmacokinetics; D005990:Glycerol / Q000008:administration & dosage / Q000138:chemical synthesis / Q000493:pharmacokinetics; D006801:Humans; D004364:Pharmaceutical Preparations / Q000008:administration & dosage* / Q000378:metabolism; D011108:Polymers / Q000008:administration & dosage* / Q000138:chemical synthesis / Q000737:chemistry / Q000493:pharmacokinetics
chemical_list: D004364:Pharmaceutical Preparations; D011108:Polymers; C024617:polyol; C043941:polyglycerol; D016650:Fluorescein-5-isothiocyanate; D005990:Glycerol