In Situ Encapsulation and Release Kinetics of pH and Temperature Responsive Nanogels

A facile synthesis of pH and temperature responsive poly( N -isopropylacrylamide) (PNIPAM) nanogels is presented. The scanning electron microscope (SEM) and dynamic light scattering (DLS) measurements indicate the formation of nanospheres of the order of 150 ± 20 and 230 ± 30 nm in case of PNIPAM (referred to as NG) and acid functionalized PNIPAM nanogels (referred to as AFNG), respectively, whereas on drug loading, the size increased to 170 ± 20 and 270 ± 20 nm, respectively at pH 7.4. Both the AFNG and amphotericin B (AmB) drug loaded AFNG (AmB-AFNG) show swelling as the pH changed from 3 to 11, but NG does not show any swelling with the change in pH. The AmB-AFNG exhibits better drug release up to ∼94% at pH 11. The better drug release observed in the case of AmB-AFNG is due to (a) swollen hydrated state of nanogel and (b) the acting repulsive forces between acid group of AFNG and AmB drug.