Design and Characterization of a PVLA-PEG-PVLA Thermosensitive and Biodegradable Hydrogel.

A set of poly(δ-valerolactone--d,l-lactide)--poly(ethylene glycol)--poly(δ-valerolactone--d,l-lactide) (PVLA-PEG-PVLA) triblock copolymers was synthesized and the solution properties were characterized using rheology, cryo-TEM, cryo-SEM, SANS, and degradation studies. This polymer self-assembles into a low viscosity fluid with flowerlike spherical micelles in water at room temperature and transforms into a wormlike morphology upon heating, accompanied by gelation. At even higher temperatures syneresis is observed.

Importance of fibrinogen in dilutional coagulopathy after neurosurgical procedures: A descriptive study.

Background And Aims: The routine management of coagulopathy during surgery involves assessing haemoglobin, prothrombin time (PT), activated partial thromboplastin time (aPTT) and platelets. Correction of these parameters involves administration of blood, fresh frozen plasma and platelet concentrates. The study was aimed at identifying the most common coagulation abnormality during neurosurgical procedures and the treatment of dilutional coagulopathy with blood components.

Phenytoin toxicity in patients with traumatic brain injury.

Background: We observed that in patients with traumatic brain injury (TBI) who did not improve as expected, serum levels of phenytoin were in the toxic range and that their sensorium improved with modification of the dose. This led us to study the usage of phenytoin in patients with TBI.

Aims: To determine the prevalence of phenytoin toxicity in TBI patients and to study the suitability of using ideal body weight (IBW) to guide phenytoin dosing.

Temperature-triggered shape-transformations in layer-by-layer microtubes.

One-dimensional layer-by-layer (LbL) nano- and microtubes have been extensively studied for energy and biomedical applications. Here, we report a temperature-triggered transformation in shape for LbL microtubes consisting of poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA). PAH/PAA microtubes were assembled onto porous sacrificial templates.

A comparison of thermal transitions in dip- and spray-assisted layer-by-layer assemblies.

Spray-assisted layer-by-layer (LbL) assembly is far more rapid than conventional dip-assisted assembly methods and has gained widespread interest recently. Even so, it has remained unclear as to how the structure and properties of the resulting LbL film vary with processing method. Here, we compared the thermal properties of poly(ethylene oxide) (PEO)/poly(acrylic acid) (PAA) and PEO/poly(methacrylic acid) (PMAA) hydrogen-bonded LbL assemblies prepared using both dip-assisted and spray-assisted deposition methods.

Thermal transitions in dry and hydrated layer-by-layer assemblies exhibiting linear and exponential growth.

Layer-by-layer (LbL) assemblies are remarkable materials, known for their tunable mechanical, optical, and surface properties in nanoscale films. However, questions related to their thermal properties still remain unclear. Here, the thermal properties of a model LbL assembly of strong polyelectrolytes, poly(diallyldimethylammonium chloride)/poly(styrene sulfonate) (PDAC/PSS), assembled from solutions of varying ionic strength (0-1.

Effect of thickness on the thermal properties of hydrogen-bonded LbL assemblies.

Layer-by-layer (LbL) assemblies have attracted much attention for their functional versatility and ease of fabrication. However, characterizing their thermal properties in relation to the film thickness has remained a challenging topic. We have investigated the role of film thickness on the glass transition temperature (T(g)) and coeffecient of thermal expansion for poly(ethylene oxide)/poly(acrylic acid) (PEO/PAA) and PEO/poly(methacrylic acid) (PEO/PMAA) hydrogen-bonded LbL assemblies in both bulk and ultrathin films using modulated differential scanning calorimetry (modulated DSC) and temperature-controlled ellipsometry.

In-plane correlations in a polymer-supported lipid membrane measured by off-specular neutron scattering.

Polymer-supported single lipid bilayers are models to study configurations of cell membranes. We used off-specular neutron scattering to quantify in-plane height-height correlations of interfacial fluctuations of such a lipid bilayer. As temperature decreased from 37 °C to 25 °C, the polymer swells and the polymer-supported lipid membrane deviates from its initially nearly planar structure.

Surface instabilities in ultrathin, cross-linked poly(N-isopropylacrylamide) coatings.

Near-the-surface instabilities with a cusplike morphology were observed in ultrathin photo-cross-linked poly(N-isopropylacrylamide) coatings upon swelling in water. The characteristic wavelength of the instability was approximately 25 times the dry thickness and scaled linearly with coating thickness between 30 and 1200 nm. Above 1200 nm, slippage of the coating along the confining substrate led to reticulated patterns with a much larger wavelength.

Model lipid membranes on a tunable polymer cushion.

A hydrated, surface-tethered polymer network capable of fivefold change in thickness over a 25-37 degrees C temperature range has been demonstrated via neutron reflectivity and fluorescence microscopy to be a novel support for single lipid bilayers in a liquid environment. As the polymer swells from 170 to 900 A, it promotes both in- and out-of-plane fluctuations of the supported membrane. The cushioned bilayer proved to be very robust, remaining structurally intact for 16 days and many temperature cycles.