Bioinspired 3D Multilayered Shape Memory Scaffold with a Hierarchically Changeable Micropatterned Surface for Efficient Vascularization

How to achieve three-dimensional (3D) cell alignment and subsequent prompt tissue regeneration remains a great challenge. Here, inspired by the interior 3D architecture of native arteries, we develop a new 3D multilayered shape memory vascular scaffold with a hierarchically changeable micropatterned surface for vascularization. The shape memory function renders the implantation of the scaffold safe and convenient via minimally invasive surgery. By co-culturing endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) on the 3D multilayered structure, the inner monolayer, which has a square micropatterned surface, can promote EC adhesion and migration, resulting in a rapid endothelialization, and the outer multilayers, which have rectangular micropatterned surfaces, can induce a circumferential alignment of VSMCs. After implantation in the cervical artery of a New Zealand rabbit for 120 days, the graft developed a high capacity for modulating cellular 3D alignment, to generate a neonatal functional blood vessel with an endothelium layer in the inner layer and multilevel VSMC circumferential alignments in the outer layers

pH-Responsive Shape Memory Poly(ethylene glycol)–Poly(ε-caprolactone)-based Polyurethane/Cellulose Nanocrystals Nanocomposite

In this study, we developed a pH-responsive shape-memory polymer nanocomposite by blending poly­(ethylene glycol)–poly­(ε-caprolactone)-based polyurethane (PECU) with functionalized cellulose nanocrystals (CNCs). CNCs were functionalized with pyridine moieties (CNC–C₆H₄NO₂) through hydroxyl substitution of CNCs with pyridine-4-carbonyl chloride and with carboxyl groups (CNC–CO₂H) via 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) mediated surface oxidation, respectively. At a high pH value, the CNC–C₆H₄NO₂ had attractive interactions from the hydrogen bonding between pyridine groups and hydroxyl moieties; at a low pH value, the interactions reduced or disappeared due to the protonation of pyridine groups, which are a Lewis base. The CNC–CO₂H responded to pH variation in an opposite manner. The hydrogen bonding interactions of both CNC–C₆H₄NO₂ and CNC–CO₂H can be readily disassociated by altering pH values, endowing the pH-responsiveness of CNCs. When these functionalized CNCs were added in PECU polymer matrix to form nanocomposite network which was confirmed with rheological measurements, the mechanical properties of PECU were not only obviously improved but also the pH-responsiveness of CNCs could be transferred to the nanocomposite network. The pH-sensitive CNC percolation network in polymer matrix served as the switch units of shape-memory polymers (SMPs). Furthermore, the modified CNC percolation network and polymer molecular chains also had strong hydrogen bonding interactions among hydroxyl, carboxyl, pyridine moieties, and isocyanate groups, which could be formed or destroyed through changing pH value. The shape memory function of the nanocomposite network was only dependent on the pH variation of the environment. Therefore, this pH-responsive shape-memory nancomposite could be potentially developed into a new smart polymer material

Electrochemically Durable Thiophene Alkanethiol Self-Assembled Monolayers

Thiophene-based redox-active self-assembled monolayers (SAMs) were prepared on gold substrates. The alkanethiol derivatives of 1TPh-OC₁₂SH and ETPh-OC₁₂SH contain thiophene (1T) and 3,4-ethylenedioxythiophene (ET) units, respectively, with unprotected (nonsubstituted) thiophene α-carbons. PhETPh-OC₁₂SH contains the ET unit, and all thiophene carbons are protected. Using these thiophene alkanethiol derivatives, we characterized the effect of thiophene carbon protection on the redox behavior of the thiophene SAMs by cyclic voltammetry. The formation of SAMs was confirmed by X-ray photoelectron spectroscopy and reflective IR. The IR peaks in the fingerprint region were assigned with the help of DFT calculations. Although 1TPh-OC₁₂SH and ETPh-OC₁₂SH SAMs lost their electrochemical activity during the first anodic scan, PhETPh-OC₁₂SH SAMs are stable and maintain their electrochemical activity for at least 1200 redox cycles

Additional file 1: of Volume, distribution and acidity of gastric secretion on and off proton pump inhibitor treatment: a randomized double-blind controlled study in patients with gastro-esophageal reflux disease (GERD) and healthy subjects

Details on MRI sequence parameters. MRI sequence parameters of the gastric volume scan were: Steady state free precession sequence (b-FFE); 30 axial image slices; slice thickness = 6 mm; field of view = 360 mm; scan matrix = 240 × 192; repetition time = 3.3 msec; echo time = 1.5 msec; flip angle = 60°; scan time = 15.5 s, one breath hold. MRI sequence parameters of the T1-B1 mapping sequence (gastric secretion scan) were for T1 mapping: Dual flip angle gradient echo sequence, 8 axial image slices, slice thickness = 15 mm, slice gap = 0.5 mm, field of view = 360 mm, scan matrix = 128 × 128, repetition time = 9 msec, echo time = 3.6 msec, flip angles = 5° and 31°, number of dummy excitations = 29 and 21, scan time = 15 s, one breath hold. For B1 mapping: Dual repetition time gradient echo sequence, slice thickness = 15 mm, slice gap = 0.5 mm, flip angle = 70°, field of view = 360 mm, scan matrix = 64 × 64, repetition time 1 (TR1) = 20 msec, repetition time 2 = 100 msec, echo time = 3.6 msec, number of dummy excitations = 6, scan time = 54 s, three breath holds. (PDF 70 kb

Tailoring Emulsions for Controlled Lipid Release: Establishing in vitro–in Vivo Correlation for Digestion of Lipids

The use of oil-in-water emulsions for controlled lipid release is of interest to the pharmaceutical industry in the development of poorly water soluble drugs and also has gained major interest in the treatment of obesity. In this study, we focus on the relevant in vitro parameters reflecting gastric and intestinal digestion steps to reach a reliable in vitro–in vivo correlation for lipid delivery systems. We found that (i) gastric lipolysis determines early lipid release and sensing. This was mainly influenced by the emulsion stabilization mechanism. (ii) Gastric mucin influences the structure of charge-stabilized emulsion systems in the stomach, leading to destabilization or gel formation, which is supported by in vivo magnetic resonance imaging in healthy volunteers. (iii) The precursor structures of these emulsions modulate intestinal lipolysis kinetics in vitro, which is reflected in plasma triglyceride and cholecystokinin concentrations in vivo

Supramolecular Organogel Based on Crown Ether and Secondary Ammoniumion Functionalized Glycidyl Triazole Polymers

A supramolecular organogel was prepared by mixing the glycidyl triazole polymers (GTP) functionalized with crown ether and secondary ammoniumion at the side groups. The polymers form an organogel above a concentration of 3 wt % via physical cross-links of the inclusion complex. The organogel responds to multiple stimuli, e.g., temperature, acid/base, and chemical species. The number of the effective cross-links estimated from the storage modulus and the affine network model suggests that some part of the binding sites could not work as the physical cross-links. Rheological measurement under large deformation showed that the storage modulus was constant up to 250% strain and larger than the loss modulus up to 600% strain. The high elasticity of the gel is attributable to the material design based on the high-molecular-weight flexible glycidyl polymers with many binding sites in the single polymer chain. The organogel also showed nice self-healing behavior. The molecular diffusion in the gel network was characterized by fluorescence correlation spectroscopy. Although the cross-link of the organogel has dynamic nature due to inclusion complexation, the diffusion behavior of the low-molecular-weight fluorescence tracer was similar to that observed in chemically cross-linked gels

Contribution of habitat variables to predicting giant panda habitat use across their utilization distributions (n = 5).

<p>Only significant variables are shown.</p

Summary of study pandas and GPS collar performance over the one year period included in this study.

<p>Summary of study pandas and GPS collar performance over the one year period included in this study.</p

Habitat use of GPS-collared giant pandas with respect to elevation over time.

<p>Values shown are the means for each month after randomly selecting one point per day. Chinese names refer to individual pandas.</p

Proportion of giant panda utilization distributions occurring in different classes of habitat characteristics.

<p>Chinese names refer to individual pandas.</p