Development of a multiphysics model to characterize the responsive behavior of urea-sensitive hydrogel as biosensor

Multiphysics model development to characterize fundamental mechanism of bio-responsive hydrogels

“…urease-loaded charged hydrogel consists of the urea-sensitive functional group bonded to their polymeric network chains. As previously revealed, the urea-sensitive hydrogel exhibits the swelling deformation response with the changes of environmental urea concentration[233]. The hydrogel swelling equilibrium is achieved, when the multiphysics interactions within the hydrogel are at a steady-state, including ion-ion, ion-solvent and polymer-solvent interactions.…”

“…The value, is to enhance the urea transport into the charged hydrogel. This perhaps is achievable if the charged hydrogel is subjected to the lower environmental temperatures, in which the polymeric network chains become more hydrophilic, and thus are able to imbibe larger quantity of water molecules into the hydrogel [233]. This could enhance the urea transport into the hydrogel [234], and perhaps enlarge the urease enzymatic activity in the hydrogel, particularly at higher urea C values.…”

“…It is commonly known that the ionization of weakly acidic and basic groups bounded onto polymeric network chains of the hydrogel is determined by the electrochemical reactions for association/dissociation of hydrogen ion with the ionizable functional components In order to capture impacts of electrical potential strength on the mobile ions concentrations in the hydrogel, equation 4.14 is incorporated into the model which gives the relationship between the polyampholytic polymeric system electrical potential and the system net charge concentration [205,233]…”

“…where In terms of hydration-induced swelling deformation of the hydrogel, the mechanical swelling pressure acting over the hydrogel-solution interface arises due to: (i) the elastic nature of the polymeric network chains, (ii) the ionic concentration difference between the hydrogel and environmental solution, (iii) the mixing between the polymeric system and the environmental solution, and (iv) the electrical interactions between the immobile charge groups and the mobile ions, which accounts for the anti-polyelectrolyte behaviors [245]. At swelling equilibrium, the hydrostatic pressure p over the hydrogel-solution interface is defined as the sum of the osmotic pressure, given as [233] ( ) ( kT is the absolute temperature in unit of energy and χ is polymer-solvent interaction parameter which indicates the disaffinity between hydrogel-solution. It is seen that the mechanical pressure on the interface between hydrogel-solution consists of a few multi-physical components, including polymer-solution, polymer-polymer, and mobileimmobile ions synergistic interactions.…”

Computational modelling and investigation of mechanical and electrochemical response of photo-sensitive hydrogels

“…The external stimulus then triggers the deformation of hydrogel by imposing an effect on polymer or surrounding solution. Based on this mechanism, stimuli-sensitive hydrogels are prepared, which could be sensitive to a wide range of stimuli, such as pH [32][33][34][35], temperature [36][37][38][39][40][41], chemical species [42][43][44][45][46][47][48], magnetic field [49][50][51][52][53], electric field [54][55][56] and light irradiation [57,58].…”