Unique doubly temperature-responsive hollow microgels are presented. These consist of two concentric thermoresponsive polymer shells made of poly(N-isopropylacrylamide) (PNIPAM) and poly(N-isopropylmethacrylamide) (PNIPMAM), respectively. The hollow particles are derived from silica-PNIPAM-PNIPMAM core-shell-shell (CSS) particles by dissolution of the silica core. Light scattering measurements reveal the twofold volume phase transition behavior that occur in the PNIPAM and PNIPMAM regions of the CSS and the respective hollow particles. In the presence of the silica core, i.e., in case of the CSS particles, the swelling of the inner shell is tremendously restricted by the core. However, after the core is dissolved, the transition of the inner shell from the swollen to the collapsed state is highly pronounced. This versatile approach allows preparing hollow particles with individually tunable properties on the particle inside and outside for various applications as multifunctional smart materials.
Natural extracellular matrices often have a filamentous nature, however, only a limited number of artificial extracellular matrices have been designed from nanofibrillar building blocks. Here we report the preparation of temperature-responsive nanofibrillar hydrogels from rod-shaped cellulose nanocrystals (CNCs) functionalized with a copolymer of N-isopropylacrylamide and N,N'-dimethylaminoethyl methacrylate. The composition of the copolymer was tuned to achieve gelation of the suspension of copolymer-functionalized CNCs at 37 °C in cell culture medium and gel dissociation upon cooling it to room temperature. The mechanical properties and the structure of the hydrogel were controlled by changing copolymer composition and the CNC-to-copolymer mass ratio. The thermoreversible gels were used for the encapsulation and culture of fibroblasts and T cells and showed low cytotoxicity. Following cell culture, the cells were released from the gel by reducing the temperature, thus, enabling further cell characterization. These results pave the way for the generation of injectable temperature-responsive nanofibrillar hydrogels. The release of cells following their culture in the hydrogels would enable enhanced cell characterization and potential transfer in a different cell culture medium.
Cononsolvency is an intriguing phenomenon where a polymer collapses in a mixture of good solvents. This cosolvent induced modulation of the polymer solubility has been observed in solutions of several...
Controlling catalytic activity by the use of smart and responsive carriers is a major challenge in research concerning supported catalysis. In homogeneous reactions, responsive polymeric carriers are often used, to...
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