Facile preparation of transparent poly (γ-glutamic acid) modified poly (vinyl alcohol) hydrogels with high tensile strength and toughness

In the present work, a transparent poly (gamma-glutamic acid) modified polyvinyl alcohol (gamma-PGA/PVA) hydrogel with excellent tensile strength and toughness was prepared by a simple and effective immersion method. Results revealed that gamma-PGA concentration and immersion time have great influence on the mechanical properties of prepared gamma-PGA/PVA hydrogels. The mechanical tensile strength of gamma-PGA/PVA hydrogel reached to 16.68 +/- 0.43 MPa with the strain of 511.64% +/- 23.38% when prepared PVA hydrogel was immersed in 20% gamma-PGA solution for 24 h (denoted as 20% gamma-PGA/PVA). Meanwhile, 20% gamma-PGA/PVA hydrogel exhibited excellent mechanical properties, such as highlevel torsion, knotting and puncture resistant, and can lift a 5 kg weight without obvious rupture. The morphology, structure, compositions and mechanism of enhanced mechanical properties were investigated. Besides the excellent mechanical properties, 20% gamma-PGA/PVA hydrogel possessed good conductivity as well as high sensitivity to external strain. Furthermore, in vitro good cytocompatibility of 20% gamma-PGA/PVA hydrogels was demonstrated by using MC3T3-E1 cells. Therefore, the prepared 20% gamma-PGA/PVA hydrogel may provide the possibility for the applications in the field of cartilage repair/regeneration, artificial skin and human motion sensor.