Figure Legends
Figure 1: Schematic drawing of a hybrid polymer network in a swollen state.Figure 2: Dependence of the type I collagen gel volume change on the elasticity-associated coefficient α, as a function of normalized temperature, T/Θ. Other physicochemical parameters are fixed at rpolym = 1, Nx = 1, and χbio = 0.161.Figure 3: Effect of the doping ratio (rpolym) of thermoresponsive pNIPAM (Θ = 315 K) on the volume phase transition temperature of a type I collagen gel (χbio = 0.161). Four values ofrpolym are presented as an example:rpolym = 0.50, 0.40, 0.35, and 0.30 from the left, with fixed α = 1.0 × 107. The secondary dependence on the crosslinking degree is displayed as decreasing saturation for each rpolym value, fromNx = 1 to 5. Room temperature:Troom; human body temperature:Tbody.Figure 4: Effect of type I collagen (and gelatin) molecular structure (represented by χbio) on the transition temperature of a hybrid gel. With the fixed parameters of α = 1.0 × 107, rpolym = 0.35, andNx = 1, the volume phase transition curves are plotted for four different biopolymer structures in the hybrid gel, that is, two rod-like conformations of collagen type I 20(χbio = 0.161 for “intact composite” helical rod with extrahelical peptides, blue solid line; andχbio = 0.107 for “pronase-digested” pure helical rod, blue dashed line) and two conformational states of gelatin chains (χbio = 0.48 for coil state, cyan solid line; and χbio = 0.49 for coil + helical states, cyan dashed line). Thermal denaturation temperature from type I collagen to gelatin is denoted as Tcol-gel.Figure 5: Optimized sets of dimensionless parameters for the hydrogel matrices of type I collagen and gelatin where thermoresponsive pNIPAM chains are doped. For collagen (blue solid line), {Vi/VNIPA, α,Nx, rpolym,χbio} = {20, 1.0 × 107, 1, 0.35, 0.161}. For gelatin (cyan dotted line), {Vi/VNIPA, α,Nx, rpolym,χbio} = {20, 1.0 × 107, 1, 0.48, 0.49}. The parameter values are chosen to enable the gel matrices remain fully swelled at Tbody and to enable complete shrinking within hyperthermal ranges where the tissues are not damaged.