Controlled release of Texas red dye-conjugated dextran and insulin from IPN hydrogel in vitro. Slow release of Texas red dye-conjugated dextran was monitored via visual observation. Specifically, (A) at 21 °C, the Texas red dye-conjugated dextran was mixed with the dispersion of IPN nanoparticles. (B) When temperature was increased to 37 °C, the Texas red dyeconjugated dextran was trapped inside the solid-like gel. By addition of phosphate-buffered saline (PBS: pH 7.4) on top of the dye-trapped gel for three hours, a small amount of Texas red dye-conjugated dextran was released into the PBS solution. (C) After 120 h, more dye can be seen in solution and less dye was found residing inside the gel. (D) After removal of the supernatant/PBS solution, the gel was cooled to 21 °C at which the solid-like gel transitioned into liquid state. A separate study was carried out to quantify the slow release of insulin from the IPN nanoparticles. (E) The average percentage of insulin released from the gel of IPN nanoparticles at 37 °C. The error bars represent the standard deviation of the compiled measurements of all three samples.