Sandcastle worms have developed protein‐based adhesives, which they use to construct protective tubes from sand grains and shell bits. A key element in the adhesive delivery is the formation of a ...fluidic complex coacervate phase. After delivery, the adhesive transforms into a solid upon an external trigger. In this work, a fully synthetic in situ setting adhesive based on complex coacervation is reported by mimicking the main features of the sandcastle worm's glue. The adhesive consists of oppositely charged polyelectrolytes grafted with thermoresponsive poly(N‐isopropylacrylamide) (PNIPAM) chains and starts out as a fluid complex coacervate that can be injected at room temperature. Upon increasing the temperature above the lower critical solution temperature of PNIPAM, the complex coacervate transitions into a nonflowing hydrogel while preserving its volume—the water content in the material stays constant. The adhesive functions in the presence of water and bonds to different surfaces regardless of their charge. This type of adhesive avoids many of the problems of current underwater adhesives and may be useful to bond biological tissues.
A fully synthetic in situ setting adhesive based on complex coacervation is reported by mimicking the main features of the sandcastle worm's glue. The adhesive consists of oppositely charged polyelectrolytes grafted with thermoresponsive poly(N‐isopropylacrylamide) chains. The adhesive starts out as an injectable fluid at room temperature. Upon increasing the temperature, the complex coacervate transitions into a nonflowing hydrogel which bonds to different surfaces.
In this work, we report the systematic investigation of a multiresponsive complex coacervate-based underwater adhesive, obtained by combining polyelectrolyte domains and thermoresponsive poly(
...-isopropylacrylamide) (PNIPAM) units. This material exhibits a transition from liquid to solid but, differently from most reactive glues, is completely held together by non-covalent interactions, i.e., electrostatic and hydrophobic. Because the solidification results in a kinetically trapped morphology, the final mechanical properties strongly depend on the preparation conditions and on the surrounding environment. A systematic study is performed to assess the effect of ionic strength and of PNIPAM content on the thermal, rheological and adhesive properties. This study enables the optimization of polymer composition and environmental conditions for this underwater adhesive system. The best performance with a work of adhesion of 6.5 J/m
was found for the complex coacervates prepared at high ionic strength (0.75 M NaCl) and at an optimal PNIPAM content around 30% mol/mol. The high ionic strength enables injectability, while the hydrated PNIPAM domains provide additional dissipation, without softening the material so much that it becomes too weak to resist detaching stress.
Rising consumer demand for healthy snacks drives a rapid market growth of protein-rich foods. While numerous studies used extrusion-based 3D food printing, only few investigated binder jet 3D ...printing to structure food materials. In this study, we investigated the feasibility of binder jet 3D printing to create protein-rich foods using Calcium Caseinate (CaCas) powder. We successfully printed foods using powder mixtures of CaCas, starch, and medium-chain triglyceride (MCT) powder. Addition of native starch to CaCas reduced swelling upon binder addition and enhanced the printability of powder mixtures. High protein model foods with different texture properties were obtained by changing ingredient, binder composition and post-treatment by heating. Food textures obtained ranged from crumbly to springy. This study highlights new opportunities to create protein-rich foods using binder jet 3D printing technology.
•It is feasible to create protein-rich foods using binder jet 3D printing.•Addition of native starch to calcium caseinate enhanced printability during powder bed printing.•Various textures were obtained by changing binder amount and calcium caseinate content.•Higher binder content in printed foods led to a more cohesive structure.•Protein content greatly influenced the springiness of the final food.
Endothelial cells are known to be an early target of preservation/reperfusion injury and acute rejection, whereas the extracellular matrix (ECM) may also play an equally important role in the ...sequelae of both events.
Syngeneic and allogeneic rat small bowel transplantations (SBTX) were performed after 6 hr of preservation. Animals were subsequently killed at defined time points for determination of ECM parameters within the graft and in plasma.
Laminin levels were significantly increased 20 min after reperfusion (syngeneic SBTX: 357+/-65.9 ng/ml; allogeneic SBTX: 361+/-79.6 ng/ml; P< or =0.01). After syngeneic transplantation, laminin levels normalized by postoperative day (POD) 7, whereas there was a rejection-induced increase after allogeneic SBTX (POD 7: 179+/-60.1 ng/ml; POD 9: 333+/-13.6 ng/ml; P< or =0.01 vs. syngeneic SBTX). This increase was accompanied by an increase in tumor necrosis factor-alpha levels at POD 9. Hyaluronic acid levels were significantly elevated after 24 hr (syngeneic SBTX: 1086+/-176 microg/L; allogeneic SBTX: 918+/-108 microg/L; P< or =0.01). After syngeneic SBTX, hyaluronic acid levels normalized by POD 7, whereas persistently higher levels were observed after allogeneic SBTX. Immunohistochemistry confirmed early changes (20 min after reperfusion) at the ECM. Anti-laminin and anti-CD44 staining normalized at POD 5 after syngeneic SBTX. After allogeneic SBTX, rejection-specific changes were evident with anti-laminin staining commencing on POD 5 and progressing until POD 9. At similar time points, increased expression of fibronectin- and interferon-gamma-positive material was evident.
The ECM can be considered to be an early target of preservation/reperfusion injury and acute rejection. Plasma parameters reliably reflected the changes observed within the graft. Laminin and hyaluronic acid levels may be used as indicators of initial graft function. Furthermore, the increase in laminin levels was an early indicator of acute rejection. Determination of these parameters may significantly improve monitoring after SBTX.
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