Dextran-crosslinked glucose responsive nanogels with a self-regulated insulin release at physiological conditions

Different glucose-responsive nanogels of N-isopropylacrylamide (NIPAM) and 4-(1,6-dioxo-2,5-diaza-7-oxamyl) phenylboronic acid (DDOPBA) were synthesized using dextran-grafted maleic acid (Dex-MA) as a crosslinker. The formed nanogels (P(NIPAM-co-Dex-co-DDOPBA)s) were verified by 1H NMR, TEM, DLS and X-ray photoelectron spectroscopy (XPS). The incorporation of DDOPBA provided a remarkable sensitivity towards glucose in physiological pH due to the existence of electron-withdrawing group in its structure. Similarly, the hydrophilic Dex-MA modulated the temperature-sensitivity near physiological temperature. The nanogels exhibited high insulin loading capacity and encapsulation efficiency and the in vitro release profiles demonstrated a glucose dependant release of the payload at physiological pH and temperature.