Redox- and pH-Responsive Nanogels Based on Thiolated Poly(aspartic acid)

Nanogels loaded with fluorescent dextran as a model drug are synthesized by the oxidation induced cross‐linking of water soluble redox responsive thiolated poly(amino acid) in miniemulsion without the introduction of any cross‐linker molecule. Two types of high energy methods, namely, ultrasonication and high pressure homogenization (HPH), are compared. Dynamic light scattering and transmission electron microscopy measurements confirm that spherical nanogels in 100–150 nm diameter range are prepared successfully by HPH method. Size and surface charge of the nanogels can easily be controlled by environmental pH. The release of encapsulated drug is triggered by the degradation of nanogels in reducing environment due to the cleavage of disulphide bonds. Redox‐ and pH‐responsive nanogels are synthesized in water‐in‐oil miniemulsion by oxidation induced cross‐linking of thiol‐modified poly(aspartic acid). Drugs can be entrapped in the gel network during preparation and released in reducing environment due to the cleavage of disulphide bonds. This feature could be beneficial in cancer therapy exploiting the reducing environment of cancer cells.