A Novel pH-Responsive Nanogel for the Controlled Uptake and Release of Hydrophobic and Cationic Solutes

The study of the mechanisms underlying the uptake and release of bioactive molecules from stimuli-responsive nanoparticles is the key to their application in biomedical fields. Here, we present the pH-controlled uptake and release of two chemically different solutes from newly synthesized nanogels, showing their potential as pH-controlled dual drug delivery systems. Nanogels were synthesized by emulsion copolymerization of methacrylic acid (MAA) and methyl acrylate (MA), and then characterized by FT-IR, 1H NMR, and dynamic light scattering (DLS). To study the encapsulation and delivery properties of PMA-PMAA nanogels, a hydrophobic thiophene fluorophore (TF) and a cationic drug, doxorubicin (DX), were chosen. The uptake and release experiments were run at different pH values and monitored by absorption and both steady-state and time-resolved photoluminescence (PL) spectroscopy. Interestingly, the release of TF and DX was obtained under basic and acidic conditions, respectively, thus demonstrating a pH-controlled dual drug release by PMA-PMAA nanogels depending on the chemical nature of the tested solutes.