Reversible Photorheological Lyotropic Liquid Crystals

We describe novel lyotropic liquid-crystalline (LLC) materials based on photoresponsive amphiphiles that exhibit rapid photoswitchable rheological properties of unprecedented magnitude between solidlike and liquidlike states. This was achieved through the synthesis of a novel azobenzene-containing surfactant (azo-surfactant) that actuates the transition between different LLC forms depending on illumination conditions. Initially, the azo-surfactant/water mixtures formed highly ordered and viscous LLC phases at 20–55 wt % water content. Spectroscopic, microscopic, and rheological analysis confirmed that UV irradiation induced the <i>trans</i> to <i>cis</i> isomerization of the azo-surfactant, leading to the disruption of the ordered LLC phases and a dramatic, rapid decrease in the viscosity and modulus resulting in a 3 orders of magnitude change from a solid (20 000 Pa) to a liquid (50 Pa) at rate of 13 500 Pa/s. Subsequent exposure to visible light reverses the transition, returning the viscosity essentially to its initial state. Such large, rapid, and reversible changes in rheological properties within this LLC system may open a door to new applications for photorheological fluids

Clinical Data Collecting System with Decision Support - User Analysis and Interface for Emergency Admissions at Sahlgrenska

 Extra high requirements are made on all systems in health care that they are functional and usable,´something, however, that is not always the case. At Emergency Admissions at Sahlgrenska University´Hospital many systems are in use at the same time and it happens that much overhead is caused by having to fill in the same information in different places. In addition, data that is gathered is to a large extent saved in free text format, which means that it cannot be used in a larger context such as research, quality control or for decision support. Data is saved in the patient file only for the treatment process of the individual patient. A data collecting system with decision support functionality could be a first step towards reducing Emergency Admissions’ costs and patients’ waiting times by providing a structured method of data collection. It is also possible that it could contribute to safer care for patients as the system could warn the staff on occasions where there may be a risk of a patient suffering from a serious, acute illness that might be difficult to diagnose. An analysis has been performed at Emergency Admissions at Sahlgrenska to distinguish possible users of a new system for collecting data with decision support. The results showed that the nurses in reception were the most suitable target group. A prototype of a user interface for gathering initial patient data at reception has been made at Emergency Admissions at Sahlgrenska. This prototype has decision support functionality for ranking the most probable diagnoses as well as providing advice on suitable tests and examinations to perform. The focus has been on usability and on adapting the system to the needs of the users. It is highly important that future users, the staff at Emergency Admissions, continue to participate in the future further development of the data gathering system so that their needs and requirements are not overshadowed by the new technology

Size and Phase Control of Cubic Lyotropic Liquid Crystal Nanoparticles

The effective use of lyotropic liquid crystalline dispersions, such as cubosomes, as drug delivery vehicles requires that they have tailored physical characteristics that suit specific therapeutics and external conditions. Here, we have developed phytantriol-based cubosomes from a dispersion of unilamellar vesicles and show that we can control their size as well as the critical packing parameter (CPP) of the amphiphilic bilayer through regulation of temperature and salt concentration, respectively. Using the anionic biological lipid 1,2-dipalmi-toylphosphatidylserine (DPPS) to prevent the cubic phase from forming, we show that the addition of phosphate buffered saline (PBS) results in a transition from small unilamellar vesicles to the cubic phase due to charge-shielding of the anionic lipid. Using dynamic light scattering, we show that the cubosomes formed following the addition of PBS are as small as 30 nm; however, we can increase the average size of the cubsosomes to create an almost monodisperse dispersion of cubosomes through cooling. We propose that this phenomenon is brought about through the phase separation of the Pluronic F-127 used to stabilize the cubosomes. To complement previous work using the salt-induced method of cubosome production, we show, using synchrotron small-angle X-ray scattering (SAXS), that we can control the CPP of the amphiphile bilayer which grants us phase and lattice parameter control of the cubosomes

Controlling the Mesostructure Formation within the Shell of Novel Cubic/Hexagonal Phase Cetyltrimethylammonium Bromide–Poly(acrylamide-acrylic acid) Capsules for pH Stimulated Release

The self-assembly of ordered structures in mixtures of oppositely charged surfactant and polymer systems has been exploited in various cleaning and pharmaceutical applications and continue to attract much interest since their discovery in the late twentieth century. The ability to control the electrostatic and hydrophobic interactions that dictate the formation of liquid crystalline phases in these systems is advantageous in manipulation of structure and rendering them responsive to external stimuli. Nanostructured capsules comprised of the cationic surfactant, cetyltrimethylammonium bromide (CTAB), and the diblock copolymer poly­(acrylamide-acrylic acid) (PAAm-AA) were prepared to assess their potential as pH responsive nanomaterials. Crossed-polarizing light microscopy (CPLM) and small-angle X-ray scattering (SAXS) identified coexisting <i>Pm</i>3<i>n</i> cubic and hexagonal phases at the surfactant–polymer interface. The hydrophobic and electrostatic interactions between the oppositely charged components were studied by varying temperature and solution pH, respectively, and were found to influence the liquid crystalline nanostructure formed. The lattice parameter of the mesophases and the fraction of cubic phase in the system decreased upon heating. Acidic conditions resulted in the loss of the highly ordered structures due to protonation of the carboxylic acid group, and subsequent reduction of attractive forces previously present between the oppositely charged molecules. The rate of release of the model hydrophilic drug, Rhodamine B (RhB), from nanostructured macro-sized capsules significantly increased when the pH of the solution was adjusted from pH 7 to pH 2. This allowed for immediate release of the compound of interest “on demand”, opening new options for structured materials with increased functionality over typical layer-by-layer capsules

Nanofibrillar Micelles and Entrapped Vesicles from Biodegradable Block Copolymer/Polyelectrolyte Complexes in Aqueous Media

Here we report a viable route to fibrillar micelles and entrapped vesicles in aqueous solutions. Nanofibrillar micelles and entrapped vesicles were prepared from complexes of a biodegradable block copolymer poly­(ethylene oxide)-<i>block</i>-poly­(lactide) (PEO-<i>b</i>-PLA) and a polyelectrolyte poly­(acrylic acid) (PAA) in aqueous media and directly visualized using cryogenic transmission electron microscopy (cryo-TEM). The self-assembly and the morphological changes in the complexes were induced by the addition of PAA/water solution into the PEO-<i>b</i>-PLA in tetrahydrofuran followed by dialysis against water. A variety of morphologies including spherical wormlike and fibrillar micelles, and both unilamellar and entrapped vesicles, were observed, depending on the composition, complementary binding sites of PAA and PEO, and the change in the interfacial energy. Increasing the water content in each [AA]/[EO] ratio led to a morphological transition from spheres to vesicles, displaying both the composition- and dilution-dependent micellar-to-vesicular morphological transitions

Glycerol Monooleate-Based Nanocarriers for siRNA Delivery in Vitro

We present studies of the delivery of short interfering ribonucleic acid (siRNA) into a green fluorescent protein (GFP) expressing cell line, using lipid nanocarriers in cubic lyotropic liquid crystal form. These carriers are based on glycerol monooleate (GMO) and employ the use of varying concentrations of cationic siRNA binding lipids. The essential physicochemical parameters of the cationic lipid/GMO/siRNA complexes such as particle size, ζ otential, siRNA uptake stability, lyotropic mesophase behavior, cytotoxicity,and gene silencing efficiency were systematically assessed. We find that the lipid nanocarriers were effectively taken up by mammalian cells and that their siRNA payload was able to induce gene silencing in vitro. More importantly, it was found that the nonlamellar structure of some of the lipid nanocarrier formulations were more effective at gene silencing than their lamellar structured counterparts. The development of cationic lipid functionalized nonlamellar GMO-based nanostructured nanoparticles may lead to improved siRNA delivery vehicles

Nanotopographic Surfaces with Defined Surface Chemistries from Amyloid Fibril Networks Can Control Cell Attachment

We show for the first time the possibility of using networks of amyloid fibrils, adsorbed to solid supports and with plasma polymer coatings, for the fabrication of chemically homogeneous surfaces with well-defined nanoscale surface features reminiscent of the topography of the extracellular matrix. The robust nature of the fibrils allows them to withstand the plasma polymer deposition conditions used with no obvious deleterious effect, thus enabling the underlying fibril topography to be replicated at the polymer surface. This effect was seen despite the polymer coating thickness being an order of magnitude greater than the fibril network. The <i>in vitro</i> culture of fibroblast cells on these surfaces resulted in increased attachment and spreading compared to flat plasma polymer films with the same chemical composition. The demonstrated technique allows for the rapid and reproducible fabrication of substrates with nanoscale fibrous topography that we believe will have applications in the development of new biomaterials allowing, for example, the investigation of the effect of extracellular matrix mimicking nanoscale morphology on cellular phenotype