pH and ion-selective swelling behaviour of keratin and keratose 3D hydrogels

Abstract

The oxidation of keratin hydrogels was optimized aiming to obtain keratose hydrogels while maintaining the original 3D structure and pH-responsive behaviour. In addition, we present a comparative study of their dual-stimuli responsive behaviour regarding the pHresponsiveness and their previously non-described ion selective responsiveness. Keratose and keratin hydrogels showed similar swellings when contracted at low pH, and the former showed steeper expansion and higher swelling than the latter at high pH. In addition, both hydrogels showed selective responsiveness toward Ca 2+ ions when expanded, and toward Cu 2+ ions when contracted. IR, Raman, ss-NMR, HRMAS NMR, SAXS, and thermal characterization demonstrated that oxidation does not interfere with the stimuli-responsive mechanisms related to protein conformation. The higher swelling of keratose hydrogels would be originated in the increase of the mobility of the chains after oxidation coupled to the hydration of sulfonic acid groups.

Dual adsorbent-photocatalytic keratin–TiO2 nanocomposite for trimethoprim removal from wastewater

“…The porous network has been described in previous works. 23,55,56 In the K hydrogel the photocurrent presents negative va lues, contra sting with the theoretical expectation that for this sample the va l ue of the photocurrent would be null. This effect could be a wa rded to electrolyte residues lodged in the anode, which upon recei ving light ca n release electrons, that prompted by the potential wi l l tra vel to the cathode, producing this negative current.…”

“…In addition, the ma tri x ca n contribute to the remediation process i f i t shows a ffinity for the ta rget contaminant. In these nanocomposites both a ds orption and degradation of the pollutants take place making this technology one of the most auspicious a lternatives [19][20][21][22] obta ined from waste materials of the livestock a nd poultry i ndustry s uch a s hair, wool, hooves, horns, feathers, etc [23][24][25] . Generally, the obta ined keratin materials (sponge or film s tructures) have good fl exibility but poor mechanical properties.…”

Triblock Superabsorbent Polymer Nanocomposites with Enhanced Water Retention Capacities and Rheological Characteristics

“… 25 To enhance the mechanical strength of SAPs, different approaches are used such as grafting with clays, 26 interpenetrating network hydrogels, 27 double-network hydrogels, 28 nanocomposite hydrogels, 29 or macromolecular microsphere hydrogels. 23 The reasons behind the uniqueness and smartness of hydrogels are their characteristic response to external stimuli such as pH, 30 , 31 ionic strength, 32 solvent composition, temperature, and light. 2 , 33 Hence, hydrogels are effective materials in a wide range of fields.…”

Smart pH-Responsive Polyaniline-Coated Hollow Polymethylmethacrylate Microspheres: A Potential pH Neutralizer for Water Purification Systems

“… 26 Drinking water with a very high or very low level of pH is potentially harmful to human consumption. 22 , 27 Drinking water with a pH less than 2.5 can cause irreversible damage to the epithelium. 28 The development of cost-effective simple materials for pH adjustment or neutralization is thus an urgent need.…”

“…After contaminant removal at the required pH, the effluent water pH has to be adjusted to neutral before delivery for human consumption to ensure health safety . Drinking water with a very high or very low level of pH is potentially harmful to human consumption. , Drinking water with a pH less than 2.5 can cause irreversible damage to the epithelium . The development of cost-effective simple materials for pH adjustment or neutralization is thus an urgent need.…”