Stimuli responsive hydrogels that can change shape in response to applied external stimuli are appealing for soft robotics, biomedical devices, drug delivery, and actuators. However, existing 3D printed shape morphing materials are non‐biodegradable, which limits their use in biomedical applications. Here, 3D printed protein‐based hydrogels are developed and applied for programmable structural changes under the action of temperature, pH, or an enzyme. Key to the success of this strategy is the use of methacrylated bovine serum albumin (MA–BSA) as a biodegradable building block to Pickering emulsion gels in the presence of
- NSF-PAR ID:
- 10202804
- Date Published:
- Journal Name:
- Soft Matter
- Volume:
- 16
- Issue:
- 15
- ISSN:
- 1744-683X
- Page Range / eLocation ID:
- 3613 to 3620
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
4D Printing of Multi‐Stimuli Responsive Protein‐Based Hydrogels for Autonomous Shape Transformations
Abstract N ‐isopropylacrylamide or 2‐dimethylaminoethyl methacrylate. These shear‐thinning gels are ideal for direct ink write (DIW) 3D printing of multi‐layered stimuli‐responsive hydrogels. While poly(N ‐isopropylacrylamide) and poly(dimethylaminoethyl methacrylate) introduce temperature and pH‐responsive properties into the printed objects, a unique feature of this strategy is an enzyme‐triggered shape transformation based on the degradation of the bovine serum albumin network. To highlight this technique, protein‐based hydrogels that reversibly change shape based on environmental temperature and pH are fabricated, and irreversibly altered by enzymatic degradation, which demonstrates the complexity that can be introduced into 4D printed systems. -
Abstract By combining the unique characteristics of molecular bottlebrushes (MBBs) and the properties of stimuli‐responsive polymers, we show that MBBs with randomly grafted poly(
n ‐butyl acrylate) and pH‐responsive poly(2‐(N ,N ‐diethylamino)ethyl methacrylate) (PDEAEMA) side chains are efficient and robust pH‐responsive emulsifiers. Water‐in‐toluene emulsions were formed at pH 4.0 and disrupted by increasing the pH to 10.0. The emulsion generation and disruption was reversible over the ten cycles investigated, and the bottlebrushes remained intact. The exceptional emulsion stability stemmed from the high interfacial binding energy of MBBs, imparted by their large molecular size and Janus architecture at the interface, as evidenced by the interfacial jamming and wrinkling of the assemblies upon reducing the interfacial area. At pH 10.0, PDEAEMA became water‐insoluble, and the MBBs desorbed from the interface, causing de‐emulsification. Consequently, we have shown that the judicious design of MBBs can generate properties of particle emulsifiers from their large size, while the responsiveness of the MBBs enables more potential applications. -
Abstract By combining the unique characteristics of molecular bottlebrushes (MBBs) and the properties of stimuli‐responsive polymers, we show that MBBs with randomly grafted poly(
n ‐butyl acrylate) and pH‐responsive poly(2‐(N ,N ‐diethylamino)ethyl methacrylate) (PDEAEMA) side chains are efficient and robust pH‐responsive emulsifiers. Water‐in‐toluene emulsions were formed at pH 4.0 and disrupted by increasing the pH to 10.0. The emulsion generation and disruption was reversible over the ten cycles investigated, and the bottlebrushes remained intact. The exceptional emulsion stability stemmed from the high interfacial binding energy of MBBs, imparted by their large molecular size and Janus architecture at the interface, as evidenced by the interfacial jamming and wrinkling of the assemblies upon reducing the interfacial area. At pH 10.0, PDEAEMA became water‐insoluble, and the MBBs desorbed from the interface, causing de‐emulsification. Consequently, we have shown that the judicious design of MBBs can generate properties of particle emulsifiers from their large size, while the responsiveness of the MBBs enables more potential applications. -
Microcapsules allow for the controlled containment, transport, and release of cargoes ranging from pharmaceuticals to fragrances. Given the interest from a variety of industries in microcapsules and other core–shell structures, a multitude of fabrication strategies exist. Here, we report on a method relying on a mixture of temperature-responsive microgel particles, poly( N -isopropylacrylamide) (pNIPAM), and a polymer which undergo fluid–fluid phase separation. At room temperature this mixture separates into colloid-rich (liquid) and colloid-poor (gas) fluids. By heating the sample above a critical temperature where the microgel particles shrink dramatically and develop a more deeply attractive interparticle potential, the droplets of the colloid-rich phase become gel-like. As the temperature is lowered back to room temperature, these droplets of gelled colloidal particles reliquefy and phase separation within the droplet occurs. This phase separation leads to colloid-poor droplets within the colloid-rich droplets surrounded by a continuous colloid-poor phase. The gas/liquid/gas all-aqueous double emulsion lasts only a few minutes before a majority of the inner droplets escape. However, the colloid-rich shell of the core–shell droplets can solidify with the addition of salt. That this method creates core–shell structures with a shell composed of stimuli-sensitive microgel colloidal particles using only aqueous components makes it attractive for encapsulating biological materials and making capsules that respond to changes in, for example, temperature, salt concentration, or pH.more » « less
-
Polymer zwitterions are generally regarded as hydrophilic and repellant or “slippery” materials. Here, a case is described in which the polymer zwitterion structure is tailored to decrease water solubility, stabilize emulsion droplets, and promote interdroplet adhesion. Harnessing the upper critical solution temperature of sulfonium‐ and ammonium‐based polymer zwitterions in water, adhesive droplets are prepared by adding organic solvent to an aqueous polymer solution at elevated temperature, followed by agitation to induce emulsification. Droplet aggregation is observed as the mixture cools. Variation of salt concentration, temperature, polymer concentration, and polymer structure modulates these interdroplet interactions, resulting in distinct changes in emulsion stability and fluidity. Under attractive conditions, emulsions encapsulating 50–75% oil undergo gelation. By contrast, emulsions prepared under conditions where droplets are nonadhesive remain fluid and, for oil fractions exceeding 0.6, coalescence is observed. The uniquely reactive nature of the selected zwitterions allows their in situ modification and affords a route to chemically trigger deaggregation and droplet dispersion. Finally, experiments performed in a microfluidic device, in which droplets are formed under conditions that either promote or suppress adhesion, confirm the salt‐responsive character of these emulsions and the persistence of adhesive interdroplet interactions under flow.