During the past few decades, thiomers have attracted interest as responsive-polymers in the design of smart hydrogels, due to thiol reactivity to physical stimuli (i.e., pH, oxygen, UV/Vis irradiation). However, thiomer potentialities have been limited by their low thiolation degree and lack of multi-responsiveness to physical cues. In this work, a new class of thiomers with tailored thiolation degree and sensitivity to multiple physical stimuli was developed. To this aim, a polyurethane (33,000 Da) was synthesised from Poloxamer® 407, 1,6-diisocyanatohexane and N-Boc diethanolamine. Secondary amino groups were exposed through Boc-removal (yield 80%, assessed by 1H NMR) giving up to 4.5 × 1020 ± 1.8 × 1019 –NH units/gpolymer (Orange II Sodium Salt colorimetric assay) without polymer chemical degradation. Polymer thermo-responsiveness was proved by the increase in micelle hydrodynamic diameter upon system heating up to 45 °C and through estimated critical micellar temperatures. Thioglycolic acid grafting to exposed amines via carbodiimide chemistry was optimised to give up to 1.73 × 1019 thiols/gpolymer (Ellman's method), while minimising disulphide bond formation. Finally, the best storage conditions against oxidation were investigated by quantifying free thiols at different time points.
Polyurethane-based thiomers: A new multifunctional copolymer platform for biomedical applications
Cassino C.;
2020-01-01
Abstract
During the past few decades, thiomers have attracted interest as responsive-polymers in the design of smart hydrogels, due to thiol reactivity to physical stimuli (i.e., pH, oxygen, UV/Vis irradiation). However, thiomer potentialities have been limited by their low thiolation degree and lack of multi-responsiveness to physical cues. In this work, a new class of thiomers with tailored thiolation degree and sensitivity to multiple physical stimuli was developed. To this aim, a polyurethane (33,000 Da) was synthesised from Poloxamer® 407, 1,6-diisocyanatohexane and N-Boc diethanolamine. Secondary amino groups were exposed through Boc-removal (yield 80%, assessed by 1H NMR) giving up to 4.5 × 1020 ± 1.8 × 1019 –NH units/gpolymer (Orange II Sodium Salt colorimetric assay) without polymer chemical degradation. Polymer thermo-responsiveness was proved by the increase in micelle hydrodynamic diameter upon system heating up to 45 °C and through estimated critical micellar temperatures. Thioglycolic acid grafting to exposed amines via carbodiimide chemistry was optimised to give up to 1.73 × 1019 thiols/gpolymer (Ellman's method), while minimising disulphide bond formation. Finally, the best storage conditions against oxidation were investigated by quantifying free thiols at different time points.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
