Preparation and biological evaluation of a glucose-responsive block copolymer nanoparticle with the ability to ameliorate diabetic kidney damage

In this study, a p(AAPBA-b-Daidzein) block copolymer was designed and synthesised using glucose-responsive 3-acrylamidophenylboronic acid (AAPBA) and esterified daidzein as structural units; this copolymer possessed anti-diabetic pharmacological activity. After confirming the chemical structure of the copolymer, nanoparticles of the copolymer were prepared using the water-in-oil method. The results of the in vitro experiments showed that nanoparticles swelled when the pH was >7 or when the glucose concentration exceeded 1.0 mg/mL. Particle size measurements showed that the size of the nanoparticles was kept in the range of 100–300 nm before and after the glucose response, which helped avoid their clearance by the liver and kidneys. As the nanoparticles swelled, insulin and esterified daidzein were continuously released. The nanoparticles subcutaneously injected into mice with streptozotocin-induced diabetes were able to quickly and continuously reduce the blood sugar levels; significantly improve renal pathological damage and reduce renal function damage, inflammatory factors and oxidative stress indicators. In summary, the p(AAPBA-b-Daidzein) glucose-responsive nanoparticles prepared in the current study possess good pH value and glucose sensitivity, can achieve a precise and controlled release of insulin and exert the pharmacological activity of esterified daidzein. Therefore, it shows potential clinical application value in the treatment of diabetes and its complications.