title: Uptake and transport of novel amphiphilic polyelectrolyte-insulin nanocomplexes by Caco-2 cells--towards oral insulin.
abstract: OBJECTIVE
  The influence of polymer architecture on cellular uptake and transport across Caco-2 cells of novel amphiphilic polyelectrolyte-insulin nanocomplexes was investigated.
  
  
  METHODS
  Polyallylamine (PAA) (15 kDa) was grafted with palmitoyl chains (Pa) and subsequently modified with quaternary ammonium moieties (QPa). These two amphiphilic polyelectrolytes (APs) were tagged with rhodamine, and their uptake by Caco-2 cells or their polyelectrolyte complexes (PECs) with fluorescein isothiocyanate-insulin (FITC-insulin) uptake was investigated using fluorescence microscopy. The integrity of the monolayer was determined by measurement of transepithelial electrical resistance (TEER), and insulin transport across the monolayers was determined.
  
  
  RESULTS
  Pa and insulin were co-localised in cell membranes, while QPa complexes were found within the cytoplasm. QPa complex uptake was not affected by calcium, cytochalasin D or nocodazole. Uptake was reduced by co-incubation with sodium azide, an active transport inhibitor. Both polymers opened tight junctions reversibly, and insulin transport through monolayers increased when QPa or Pa was used.
  
  
  CONCLUSIONS
  These APs have been shown to be taken up by Caco-2 cells and reversibly open tight cell junctions. Further work is required to optimise these formulations with a view to maximising their potential to facilitate oral delivery of insulin.
authors.affiliation: School of Pharmacy and Life Sciences, The Robert Gordon University, Schoolhill, Aberdeen, AB10 1FR, UK.
authors.forename: Colin
authors.initials: C
authors.lastname: Thompson
authors.forename: Woei Ping
authors.initials: WP
authors.lastname: Cheng
authors.forename: Pramod
authors.initials: P
authors.lastname: Gadad
authors.forename: Karen
authors.initials: K
authors.lastname: Skene
authors.forename: Mhairi
authors.initials: M
authors.lastname: Smith
authors.forename: Gillian
authors.initials: G
authors.lastname: Smith
authors.forename: Alastair
authors.initials: A
authors.lastname: McKinnon
authors.forename: Rachel
authors.initials: R
authors.lastname: Knott
mesh_terms: D000284:Administration, Oral; D001692:Biological Transport; D018938:Caco-2 Cells; D018929:Cell Culture Techniques; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D004573:Electrolytes / Q000737:chemistry*; D006801:Humans; D007004:Hypoglycemic Agents / Q000008:administration & dosage* / Q000737:chemistry / Q000493:pharmacokinetics; D007328:Insulin / Q000008:administration & dosage* / Q000737:chemistry / Q000493:pharmacokinetics; D046529:Microscopy, Electron, Transmission; D008856:Microscopy, Fluorescence; D058726:Nanoconjugates / Q000737:chemistry*; D010169:Palmitic Acids / Q000737:chemistry; D011073:Polyamines / Q000737:chemistry; D013388:Succinimides / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry*; D014325:Tromethamine / Q000737:chemistry
chemical_list: D004573:Electrolytes; D007004:Hypoglycemic Agents; D007328:Insulin; C507204:N-hydroxysuccinimidyl palmitate; D058726:Nanoconjugates; D010169:Palmitic Acids; D011073:Polyamines; D013388:Succinimides; D013501:Surface-Active Agents; D014325:Tromethamine; C063994:polyallylamine