Regimes of microstructural evolution as observed from rheology and surface morphology of crosslinked poly(vinyl alcohol) and hyaluronic acid blends during gelation

Abstract

Hyaluronic acid (HA)‐based materials are being investigated because of their role in biological fluids and tissues. Poly(vinyl alcohol) (PVA) when blended with HA at different compositions leads to superior mechanical properties compared to pure HA. The PVAHA blend hydrogels are potential candidates for pharmaceutical, biomedical, and cosmetic applications. It is essential to understand the structure, gelation time, and morphological properties of these hydrogels. In this work, a blend system of PVA crosslinked with glutaraldehyde in the presence of HA is studied. Semidilute solutions of PVA and HA are blended, followed by gelation due to crosslinking. The crosslinked gels as well as the gel cast membranes were examined. The effect of HA on the gelation process is investigated using rheological characterization. It is shown that kinetics of gelation is influenced by HA content, though storage modulus of the gels is influenced marginally. The structural features of PVAHA gels were also probed with scanning electron microscopy and dynamic light scattering. It is argued that there is a complex interplay between intra‐ and intermolecular crosslinking of PVA and PVA–HA interactions during the gel formation. Based on the insights obtained from various probing techniques for PVAHA gels with different HA content, three broad structural features were identified. It is shown that the hydrogel is semi‐interpenetrating network at lower HA content (<10% HA), cocontinuous morphology at moderate HA content and with domains at high HA content (>20% HA). © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41081.

Selection of geometry for nonlinear rheology using large amplitude oscillatory shear: Poly (vinyl alcohol) based complex network systems

“…The individual solutions were then mixed on volume basis and stirred for 3 h to prepare the PVA-borax systems, following previous works. [12,14,15] Likewise, PVA solution of 5 wt% was prepared at a temperature of 80 C for 8 h. HA solution of 1 wt% was prepared at room temperature. The individual solutions were mixed on volume basis and stirred for 5 h, to form PVA-HA solutions of desired composition.…”

“…A crosslinker solution, comprising 3 mL of 50 vol% methanol (quencher), 2 mL of 10 vol% acetic acid (buffer), 1 mL of 25 vol% GA and 1 mL of 10 vol% sulphuric acid was prepared to selectively crosslink PVA in the above solutions to form their semi-interpenetrating network gels. Although several compositions were investigated and reported in previous works, [12,14,15] representative PVA based systems explored for the purpose of this study are listed in Table 2.…”

“…This results in the formation of chemically crosslinked PVA-HA gel with strong semi interpenetrating network structure (Figure 1E). [8,[12][13][14][15] Nonlinear rheology is known to be an effective tool for probing network-level microstructural changes in such systems. They exhibit diverse intracycle response features during oscillatory shear specific to the nature of crosslinking.…”

“…They exhibit diverse intracycle response features during oscillatory shear specific to the nature of crosslinking. [12,14] In recent times, large amplitude oscillatory shear (LAOS) has become a powerful technique to characterize polymeric systems, ranging from blends, composites to crosslinked gels. [16][17][18][19] Therefore, special care with respect to testing conditions/geometry is essential for systematic analysis and interpretation of the material response.…”

Recent Advances in Cardiac Tissue Engineering for the Management of Myocardium Infarction

“…For cell attachment and proliferation, HA alone is inadequate. Cell adhesion can be achieved using hyaluronan hydrogels crosslinked with thiol-reactive poly(ethylene glycol) diacrylate [113,114].…”