Acrylamide [HRP]

Materials used in organ mimics for medial simulation and education require tissue-like softness, toughness, and hydration to give clinicians and students accurate tactile feedback. However, there is a lack of materials that satisfy these requirements. Herein, we demonstrate that a stretchable and tough polyacrylamide hydrogel is useful to build organ mimics that match softness, crack growth resistance, and interstitial water of real organs. Varying the acrylamide concentration between 29 or 62% w/w with a molar ratio between cross-linker and acrylamide of 1 : 10 800 resulted in a fracture energy around similar to 2000 J m(-2). More interestingly, this tough gel permitted variation of the elastic modulus from 8 to 62 kPa, which matches the softness of brain to vascular and muscle tissue. According to the rheological frequency sweep, the tough polyacrylamide hydrogels had a greatly decreased number of flow units, indicating that when deformed, stress was dispersed over a greater area. We propose that such molecular dissipation results from the increased number of entangled polymers between distant covalent cross-links. The gel was able to undergo various manipulations including stretching, puncture, delivery through a syringe tip, and suturing, thus enabling the use of the gel as a blood vessel model for microsurgery simulation.

Polymer-grafting to porous materials is an effective way to create protein ion-exchangers of high capacity and uptake rate because the 3D architecture of the polymeric ion exchange groups provides high binding space and facilitated transport of the bound protein. Herein, a new anion exchanger was fabricated by grafting (3-acrylamide propyl) trimethyl ammonium chloride (APTAC) onto Sepharose FF gel for protein adsorption and chromatography. The ion exchanger, denoted as FF-pAPTAC, presented high capacity but limited uptake rate in bovine serum albumin (BSA) adsorption due to the high charge density of the cationic polymer chains. To solve the problem, we proposed to copolymerize APTAC with an electroneutral monomer, acrylamide (AM), onto Sepharose FF to modulate the charge density of the grafted polymer chains. By decreasing the feeding molar ratio of APTAC to AM, the ionic capacity (IC) of the copolymerized resins, FF-p(AM-APTAC)n (n denotes IC in mmol/L), decreased, but the chain length could be remained almost unchanged due to the similar reactivity ratios of the two monomers. With decreasing IC, the static adsorption capacity (q(m)) of FF-p(AM-APTAC)n decreased gradually because of the decline of protein binding sites. The uptake rate, however, represented by the ratio of effective pore diffusivity to the free solution diffusivity (D-e/D-0), exhibited a strong uptrend with decreasing IC, reaching similar to 2.5-fold of the maximum observed with FF-pAPTACn. It is considered that the decrease of charge density weakened protein binding strength to the chains and increased the chain flexibility, which consequently facilitated the transport of bound proteins on the chains. Moreover, at the same IC, each FF-p(AM-APTAC)n displayed similar adsorption capacity but high uptake rate as compared with its FF-pAPTACn counterpart mainly due to the longer chain length of the copolymer. Particularly, similar to 6.5-fold enhancement of D-e/D-0 was observed at IC = 50 +/- 2 mmol/L. Both high adsorption capacity and uptake rate made FF-p(AM-APTAC)n exhibit superior dynamic binding performance. The findings proved that reducing chain charge density by copolymerizing an electroneutral monomer was promising for fabrication of high-performance protein ion exchangers. (C) 2020 Elsevier B.V. All rights reserved.