3D-Printable Biodegradable Polyester Tissue Scaffolds for Cell Adhesion

Additive manufacturing, or three-dimensional (3D) printing, has emerged as a viable technique for the production of vascularized tissue engineering scaffolds. In this report, a biocompatible and biodegradable poly(tri(ethylene glycol) adipate) dimethacrylate was synthesized and characterized for suitability in soft-tissue scaffolding applications. The polyester dimethacrylate exhibited highly efficient photocuring, hydrolyzability, and 3D printability in a custom microstereolithography system. The photocured polyester film demonstrated significantly improved cell attachment and viability as compared with controls. These results indicate promise of novel, printable polyesters for 3D patterned, vascularized soft-tissue engineering scaffolds.

A Novel Long-Life Air Working Electro-Active Actuator Based on Cellulose and Polyurethane Blend

In this paper, electro-active actuator made with cellulose and polyurethane blend film is prepared, which can show high bending displacement in the air with room humidity condition. To fabricate this actuator, cotton cellulose was dissolved into a N,N-dimethylacetamide (DMAc) and lithium chloride (LiCl) solvent system. Polyurethane prepared by poly[di(ethylene glycol) adipate] and hexamethylene diisocyanate (HDI) was mixed with DMAc cellulose solution by stirring. The mixed solution was cast to form a film followed by depositing thin gold electrode on both sides of the film. The actuator was actuated under AC voltage at an ambient condition by changing the actuation voltage, frequency and time. The actuator revealed a large bending displacement under low activation voltage, low electrical power consumption and good durability at room condition. This cellulose- polyurethane blend actuator is suitable for dry and durable actuator and promising for many biomimetic applications in foreseeable future.

Alternative polymer precipitants for protein crystallization

A set of 16 inexpensive and commercially available polymer precipitants were tested for protein crystallization. Eight of them were found suitable: polyethylene glycol dimethyl ether of molecular weight (MW) 500, 1000 and 2000; di[poly(ethylene glycol)] adipate, MW 900; poly(ethylene glycol-ran-propylene glycol), MW 2500 and 12000; poly(acrylic acid) sodium salt, MW 2100; and polyethylene glycol methyl ether methacrylate, MW 1100. Two new crystallization screens, PolyA and PolyB, were formulated using these eight polymers, each containing 96 solutions – four polymers in combination with 24 common salts and buffers, covering pH values from 4.5 to 9.0. The screens were tested on 29 proteins, 21 of which were crystallized. The tests confirmed the applicability of the eight polymers as precipitants for protein crystallization.

Viscometric Study of Poly(ester Urethane) Solutions: 2. Influence of Hard-Segment Composition on the Unperturbed Dimensions

Using viscometry, we have studied the dilute solution property of segmented poly(ester urethane)s obtained by the reaction of aromatic diisocyanates with poly(ethylene glycol)adipate and 4,4′-dihidroxydiethoxydiphenyl sulphone as chain extender, using a multistep polyaddition process. A new method proposed by Qian et al. was utilized for the determination of unperturbed dimensions of poly(ester urethane)s having different hard segments by the measurement of the intrinsic viscosity at non-theta conditions only. The influence of the hard segments on the unperturbed dimensions of these polymers was observed. The diisocyanates with methyl substituents in the hard segments, such as 2,4-tolylene diisocyanate, have smaller unperturbed dimensions compared with the samples containing 4,4′-methylene diphenylene diisocyanate, which are believed to possess significant chain rigidity because of the high cohesive energy and bulkiness of the benzene ring.

Synthesis and Properties of Unsaturated Poly(Urethane-Imide)s

Unsaturated poly(urethane-imide)s were prepared by the reaction of unsaturated polyurethane prepolymers with maleic anhydride. The polyurethane prepolymers were synthesized by the reaction of 4,4′-methylene diphenyl diisocyanate (MDI) with unsaturated polyesters having a molecular weight of about 500 or with a mixture of unsaturated and saturated polyesters having a molecular weight of about 2000. The unsaturated polyurethane prepolymers reacted with maleic anhydride until the evolution of carbon dioxide ceased to yield unsaturated poly(urethane-imide)s. These polymers exhibited improved solubility in organic solvents and formed flexible films showing fairly good stress-strain properties. Compared to conventional polyurethanes based on MDI and poly(ethylene glycol adipate) these polymers exhibited better thermal stabilities due to the presence of the imide groups.