Additive manufacturing allows three-dimensional printing of polymeric materials together with cells, creating living materials for applications in biomedical research and biotechnology. However, an understanding of the cellular phenotype within living materials is lacking, which is a key limitation for their wider application. Herein, we present an approach to characterize the cellular phenotype within living materials. We immobilized the budding yeast Saccharomyces cerevisiae in three different photo-cross-linkable triblock polymeric hydrogels containing F127-bis-urethane methacrylate, F127-dimethacrylate, or poly(alkyl glycidyl ether)-dimethacrylate. Using optical and scanning electron microscopy, we showed that hydrogels based on these polymers were stable under physiological conditions, but yeast colonies showed differences in the interaction within the living materials. We found that the physical confinement, imparted by compositional and structural properties of the hydrogels, impacted the cellular phenotype by reducing the size of cells in living materials compared with suspension cells. These properties also contributed to the differences in immobilization patterns, growth of colonies, and colony coatings. We observed that a composition-dependent degradation of polymers was likely possible by cells residing in the living materials. In conclusion, our investigation highlights the need for a holistic understanding of the cellular response within hydrogels to facilitate the synthesis of application-specific polymers and the design of advanced living materials in the future.

We describe the synthesis, characterization and direct-write 3D printing of triblock copolymer hydrogels that have a tunable response to temperature and shear stress. In aqueous solutions, these polymers utilize the temperature-dependent self-association of poly(alkyl glycidyl ether) 'A' blocks and a central poly(ethylene oxide) segment to create a physically crosslinked three-dimensional network. The temperature response of these hydrogels was dependent upon composition, chain length and concentration of the 'A' block in the copolymer. Rheological experiments confirmed the existence of sol-gel transitions and the shear-thinning behavior of the hydrogels. The temperature-and shear-responsive properties enabled direct-write 3D printing of complex objects with high fidelity. Hydrogel cytocompatibility was also confirmed by incorporating HeLa cells into select hydrogels resulting in high viabilities over 24 h. The tunable temperature response and innate shear-thinning properties of these hydrogels, coupled with encouraging cell viability results, present an attractive opportunity for additive manufacturing and tissue engineering applications.

Herein, we describe a method to produce yeast-laden hydrogel inks for the direct-write 3D printing of cuboidal lattices for immobilized whole-cell catalysis.

Poly(dichlorophosphazene) is a versatile precursor material for accessing new polymeric materials via the introduction of various side groups by chlorine replacement reactions. Herein, methods are described for the synthesis of a new series of phosphazene single-and mixed-substituent high polymers containing cyclic aliphatic rings, −C n H 2n−1 (where n = 4−8). These reactions were preceded by model reactions using small molecule cyclic trimeric phosphazenes. The new high polymers are amorphous, transparent, and film-and membrane-forming materials with a wide range of glass transition temperatures (−60 to +40°C) depending on the side groups and cosubstituents. All are hydrophobic and resistant to hydrolytic breakdown.

Herein, we describe a multistimuli-responsive hydrogel that can be 3D printed via a direct-ink write process to afford cross-linked hydrogel networks that can be postfunctionalized with thiol-bearing molecules. Poly(alkyl glycidyl ether)s with methacrylate groups at their termini were synthesized and selfassembled into hydrogels with three key stimuli-responsive behaviors necessary for extrusion-based 3D printing: a sol−gel temperature response, shear-thinning behavior, and the ability to be photochemically cross-linked. In addition, the chemically crosslinked hydrogels demonstrated a temperature-dependent swelling consistent with an LCST behavior. Pyridyl disulfide urethane methacrylate (PDS-UM) monomers were introduced into the network as a thiol-reactive handle for postfunctionalization of the hydrogel. The reactivities of these hydrogels were investigated at different temperatures (5, 25, and 37 °C) and swelling statuses (ascured/preswollen) using glutathione as a reactive probe. To illustrate the versatility of the platform, we conjugated a number of additional thiol-containing probes such as proteins, polymers, and small molecules to the hydrogel network at different temperatures, pH values, and concentrations. In a final demonstration of the multistimuli-responsive hydrogel platform, a customized DIW 3D printer was used to fabricate a printed object that was subsequently conjugated with a fluorescent tag and displayed the ability to change in size with environmental temperature.

Additive manufacturing allows three-dimensional printing of polymeric materials together with cells, creating living materials for applications in biomedical research and biotechnology. However, understanding the cellular phenotype within living materials is lacking and a key limitation for their wider application. Herein, we present an approach to characterize the cellular phenotype within living materials. We immobilized the budding yeast Saccharomyces cerevisiae in three different photocross-linkable triblock polymeric hydrogels containing F127-bis-urethane methacrylate, F127-dimethacrylate, or poly(alkyl glycidyl ether)-dimethacrylate. Using optical and scanning electron microscopy, we showed that hydrogels based on these polymers were stable under physiological conditions, but yeast colonies showed differences in the interaction within the living materials. We found that the physical confinement, imparted by compositional and structural properties of the hydrogels, impacted the cellular phenotype by reducing the size of cells in living materials compared with suspension cells. These properties also contributed to the differences in immobilization patterns, growth of colonies, and colony coatings. We observed that a composition-dependent degradation of polymers was likely possible by cells residing in the living materials. In conclusion, our investigation highlights the need for a holistic understanding of the cellular response within hydrogels to facilitate the synthesis of application-specific polymers and the design of advanced living materials in the future.

Medical adhesives are used to secure wound care dressings and other critical devices to the skin. Without means of safe removal, these stronger adhesives are difficult to painlessly remove from the skin and may cause medical-adhesive-related skin injuries (MARSI), including skin tears and an increased risk of infection. Lower-adhesion medical tapes may be applied to avoid MARSI, leading to device dislodgement and further medical complications. This paper outlines the development of a high-adhesion medical tape designed for low skin trauma upon release. By warming the skin-attached tape for 10–30 s, a significant loss in adhesion was achieved. A C14/C18 copolymer was developed and combined with a selected pressure-sensitive adhesive (PSA) material. The addition of 1% C14/C18 copolymer yielded the largest temperature-responsive drop in surface adhesion. The adhesive film was characterized using AFM, and distinct nanodomains were identified on the exterior surface of the PSA. Our optimized formulation yielded 67% drop in adhesion when warmed to 45 °C, perhaps due to melting nanodomains weakening the adhesive–substrate boundary layer. Pilot clinical testing resulted in a significant decrease in pain when a heat pack was used for removal, giving an average pain reduction of 66%.

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