Drug release of pH/temperature-responsive calcium alginate/poly(N-isopropylacrylamide) semi-IPN beads

Macromol Biosci. 2006 May 23;6(5):358-63. doi: 10.1002/mabi.200600013.


A series of semi-interpenetrating, polymer network (semi-IPN), hydrogel beads, composed of calcium alginate (Ca-alginate) and poly(N-isopropylacrylamide) (PNIPAAM), were prepared for a pH/temperature-sensitive drug delivery study. The equilibrium swelling showed the independent pH- and thermo- responsive nature of the developed materials. At pH=2.1, the release amount of indomethacin incorporated into these beads was about 10% within 400 min, while this value approached to 95% at pH=7.4. The release rate of the drug was higher at 37 degrees C than that at 25 degrees C and increased slightly with increasing PNIPAAM content. These results suggest that the Ca-alginate/PNIPAAM beads have the potential to be used as an effective pH/temperature sustainable delivery system of bioactive agents. [GRAPHS: SEE TEXT] A summary of the temperature- and pH-dependence on the release of the drug over a period of 450 min. The effect of the temperature on the swelling of the beads is shown in the inset.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acrylic Resins / chemistry*
  • Alginates / chemistry*
  • Biocompatible Materials / chemistry*
  • Delayed-Action Preparations
  • Drug Carriers / chemistry*
  • Glucuronic Acid / chemistry
  • Hexuronic Acids / chemistry
  • Hydrogels
  • Hydrogen-Ion Concentration
  • In Vitro Techniques
  • Indomethacin / administration & dosage
  • Materials Testing
  • Temperature


  • Acrylic Resins
  • Alginates
  • Biocompatible Materials
  • Delayed-Action Preparations
  • Drug Carriers
  • Hexuronic Acids
  • Hydrogels
  • poly-N-isopropylacrylamide
  • Glucuronic Acid
  • Indomethacin