An l -proline based thermoresponsive and pH-switchable nanogel as a drug delivery vehicle

• Published in: Polymer chemistry Vol. 9; no. 17; pp. 2271 - 2280
• Main Authors: Salinas, Y., Castilla, A. M., Resmini, M.
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 01.01.2018
• Subjects: Acrylamide; Cobalt; Copolymerization; Crosslinking; Drug delivery systems; Hydrophobicity; Isopropylacrylamide; Monomers; Photon correlation spectroscopy; Polymer chemistry; Proline; Stimuli
• ISSN: 1759-9954; 1759-9962
• DOI: 10.1039/C8PY00308D

The synthesis and characterisation of a novel dual stimuli-responsive nanogel, based on thermoresponsive N-n -propylacrylamide and an l -proline based monomer acting as a pH-switcher, is reported here. The effect of the crosslinker/co-monomer ratios was studied to demonstrate the relationship between the chemical structure, degree of hydrophobicity and physico-chemical characteristics of the nanogels. Tailoring of the thermoresponsive properties was achieved by altering crosslinker N , N ′-methylenebis(acrylamide) content between 10 and 50 mol%, in combination with three thermoresponsive monomers N-n -isopropylacrylamide, N-n -propylacrylamide and N -acryloylpyrrolidine. A library of 25 different combinations of monomers and crosslinkers was obtained and characterised by dynamic light scattering and UV-Vis spectroscopy. The nanogel based on N-n -propylacrylamide and 10 mol% crosslinker was then co-polymerised with an l -proline based monomer to introduce a pH-switch. This nanogel was obtained with <10 nm particle size and a VPTT ca. 43 °C, and was used to demonstrate a drug delivery capability using Nile Blue A as a model drug. Detailed studies demonstrated maximum drug release at lower pH and 43 °C, thus confirming the dual stimuli switch.