Electrospun microfibers (MFs) composed of pH and temperature responsive polymers can be used for controllable and variable\ndelivery of ibuprofen. First, electrospinning technique was employed to prepare poly(????-caprolactone) (PCL) and poly(Nisopropylacrylamide-\nco-methacrylic acid) (pNIPAM-co-MAA) MFs containing ibuprofen. It was found that drug release rates\nfrom PCL MFs cannot be significantly varied by either temperature (22ââ?¬â??40?C) or pH values (1.7ââ?¬â??7.4). In contrast, the ibuprofen\n(IP) diffusion rates from pNIPAM-co-MAA MFs were very sensitive to changes in both temperature and pH. The IP release from\npNIPAM-co-MAA MFs was highly linear and controllable when the temperature was above the lower critical solution temperature\n(LCST) of pNIPAM-co-MAA (33?C) and the pH was lower than the pK???? of carboxylic acids (pH 2). At roomtemperature, however,\nthe release rate was dramatically increased by nearly ten times compared to that at higher temperature and lower pH. Such a\nunique and controllable drug delivery system could be naturally envisioned to find many practical applications in biomedical and\npharmaceutical sciences such as programmable transdermal drug delivery.
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