Starch and chitosan oligosaccharides as interpenetrating phases in poly(N-isopropylacrylamide) injectable gels

• Physical blends were prepared to obtain thermosensitive gels PNIPA/polysaccharides.
• Rheological test allowed verifying the injectability of the gels.
• Gels showed a LCST ~ 37 °C, which makes them interesting for biomedical applications.
• Porosity is a function of hydrophobicity/hydrophilicity/molecular weight of phases.
• The PNIPA/starch gel showed better morphology as scaffold for tissue engineering.

Thermosensitive interpenetrating gels were prepared by physically blending poly(N-isopropylacrylamide) (PNIPA) as the matrix and the following polysaccharides as interpenetrating phases: chitosan oligosaccharides (identified as QNAD and QNED) and soluble starch (STARCH). The molecular weight of the dispersed phase, the free water/bound water ratio and the thermosensitivity (transition temperature: LCST) of the gels were determined. It was found that these gels are pseudoplastic and that their viscosity depends on the molecular weight of the dispersed phase. LCST transition occurred around 35–37 °C. The morphology of the porosity of the freeze-dried samples was studied by Scanning Electron Microscopy (SEM). An in vitro test of cell hemolysis on blood agar showed that these gels are noncytotoxic. According to the results obtained, these interpenetrating gels show characteristics of an injectable material, and have a transition LCST at body temperature, which reinforces their potential to be used in the surgical field and as scaffolds for tissue engineering.