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A novel dual ionic network cellulose-based composite conductive self-healing hydrogel was fabricated with high elongation, rapid recoverability, high conductive sensitivity, self-healing ability and good biocompatibility. The hydrogel was constructed by the synergistic complexations of new-fashioned bidentate aldehyde groups on dialdehyde cellulose nanofibers (DACNFs) and carboxyl groups of acrylic acid (AA) with Fe 3+ . The elongation (~1300%) of the hydrogel containing 1 wt% DACNFs was approximate 13-fold of the pure PAA hydrogel and can recover to original state within 2 min after 80% compression. The self-healing efficiency increased with the addition of DACNFs in the dual ionic network cellulose-based composite conductive self-healing hydrogel. The hydrogel configured for a wearable test and showed high stretching sensitivity with a gauge factor of 13.82 at strain within 1.6%. The gauge factor (GF) decrease with the incremental strain within 20%. GF were 0.696 between 20% and 300% strain, 0.837 within 300% and 500%. Meanwhile, the current had a good linear relationship with the bending angles of hydrogels and pressure on hydrogels, which may provide a great potential in monitor both minor variations and large movements., (Copyright © 2021 Elsevier B.V. All rights reserved.)

In this work, sodium alginate (SA) based "all-natural" composite bio-sponges were designed for potential application as wound care scaffold. The composite bio-sponges were developed from the aqueous amalgamation of SA and cellulose nanofibres (CNFs) in bio-extracts like Rice water (Rw) and Giloy extract (Ge). These sponges were modified by employing a simple coating strategy using vegetable oil-based bio-polyurethane (BioPU) to tailor their physicochemical and biological properties so as to match the specific requirements of a wound care scaffold. Bio-sponges with shared interpenetrating polymeric network structures were attained at optimized BioPU coating formulation. The interpenetration of BioPU chains within the sponge construct resulted in the formation of numerous micro-networks in the interconnected microporous structure of sponges (porosity ≥75%). The coated sponge showed a superior mechanical strength (compressive strength ~3.8 MPa, compressive modulus ~35 MPa) with appreciable flexibility and recoverability under repeated compressive loading-unloading cycles. A tunable degradation behaviour was achieved by varying BioPU coating concentrations owing to the different degree of polymer chain entanglement within the sponge construct. The physical entanglement of BioPU chains with core structural components of sponge improved their structural stability by suppressing their full fragmentation in water-based medium without affecting its swelling behaviour (swelling ratio > 1000%). The coated sponge surface has provided a suitable moist-adherent physical environment to support the adhesion and growth of skin cells (HaCaT cells). The MTT (3-(4,5-dimethyl thiazolyl-2)-2,5-diphenyltetrazolium bromide) assay and hemolytic assay revealed the non-toxic and biocompatible nature of coated sponges in vitro. Moreover, no signs of skin erythema or edema were observed during in vivo dermal irritation and corrosion test performed on the skin of Sprague Dawley (SD) rats. Our initial observations revealed the credibility of these sponges as functional wound care scaffolds as well as its diverse potential as a suitable substrate for various tissue engineering applications., (Copyright © 2020 Elsevier B.V. All rights reserved.)