Fig. 2.

Modulation of matrix stiffness in 3D gels. (A) Liposomes loaded with gold nanorods and either CaCl₂ (stiffening) or DTPA (softening) are distributed throughout a 3D alginate gel and irradiated for various times. (B) Irradiation induces release of liposomal cargo and either stiffening or softening. (C) Stiffening rate and magnitude can be varied by changing the initial stiffness of the gels. All irradiation timepoints are statistically significantly greater than unirradiated controls (P < 0.05) except 10 mM, 60 s. (D) Longitudinal study to demonstrate stiffening can be induced at least 14 d after initial gelation. (E) Multiple irradiations of the same gel on consecutive days cause gradual stiffening. * denotes statistical significance of P < 0.05.