FTIR Spectroscopic Study of the Secondary Structure of Globular Proteins in Aqueous Protic Ionic Liquids

Protein misfolding is a detrimental effect which can lead to the inactivation of enzymes, aggregation, and the formation of insoluble protein fibrils called Amyloids. Consequently, it is important to understand the mechanism of protein folding, and under which conditions it can be avoided or mitigated. Ionic liquids (ILs) have previously been shown as capable of increasing or decreasing protein stability, depending on the specific IL, IL concentration and which protein. However, a greater range of IL-proteins need to be systematically explored to enable the development of structure-property relationships. In this work, the secondary structure of four proteins, lysozyme, trypsin, β-lactoglobulin and α-amylase, were studied in aqueous solutions of 10 protic ionic liquids (PILs) with 0–50 mol% PIL present. The PILs consisted of ethyl-, ethanol-, diethanol- and triethanolammonium cations paired with nitrate, formate, acetate or glycolate anions. The secondary structure was obtained using ATR-FTIR spectroscopy. It was found that lysozyme and trypsin retained its secondary structure, consistent with a native folded state, for many of the aqueous IL solutions which contained a formate or nitrate anion at the most dilute concentrations. In contrast, α-amylase and β-lactoglobulin generally had poor stability and solubility in the IL solutions. This may be due to the isoelectric point of α-amylase and β-lactoglobulin being closer to the pH of the solvents. All four proteins were insoluble in ethyl-, ethanol- and diethanolammonium acetate, though α-amylase and trypsin retained their secondary structure in up to 20 and 30 mol% of triethanolammonium acetate, respectively. It was evident that the protein stability varied substantially depending on the protein-IL combination, and the IL concentration in water. Overall, the findings indicated that some ions and some ILs were in general better for protein solubility and stability than others, such as acetate leading to poor solubility, and EAN and EAF generally leading to better protein stability than the other PILs. This study of four proteins in 10 aqueous PILs clearly showed that there are many complexities in their interactions and no clear general trend, despite the similarities between the PIL structures. This highlights the need for more and larger studies to enable the selection and optimization of PIL solvents used with biomolecules

Health First: An evidence-based alcohol strategy for the UK

Alcohol is taken for granted in the UK today. It is easy to get hold of, increasingly affordable, advertised everywhere and accepted by many as an integral part of daily life. Yet, despite this, the great majority of the population recognise the harm that alcohol causes. They believe that drinking damages health, drives anti social behaviour, harms children and families and creates huge costs for the NHS and the Police. They are right. Every year in the UK, there are thousands of deaths and over a million hospital admissions related to drinking. More than two in five (44%) violent crimes are committed under the influence of alcohol, as are 37% of domesti c violence incidents. One fifth of all violent crime occurs in or near pubs and clubs and 45% of adults avoid town centres at night because of drunken behaviour. The personal, social and economic cost of alcohol has been estimated to be up to £55bn for England and £7.5bn for Scotland. None of this should be taken for granted. The impact of drinking on public health and community safety is so great that radical steps are needed to change our relationship with alcohol. We need to imagine a society where low or no alcohol consumpti on is the norm, drunkenness is socially unacceptable and town centres are safe and welcoming places for everyone to use. Our vision is for a safer, healthier and happier world where the harm caused by alcohol is minimised. This vision is achievable. But only if we tackle the primary drivers of alcohol consumption. The evidence is clear: the most effective way to reduce the harm from alcohol is to reduce the affordability, availability and attractiveness of alcohol products. It is not enough to limit the damage once people are drunk, dependent, ill or dying. We need to intervene earlier in order to reduce consumption across the entire population. The tools are available. The ‘four Ps' of the marketing mix - price, product, promotion and place - are used by alcohol producers and retailers to increase their sales of alcohol. They can also be used by government to reduce alcohol sales, alcohol consumption and alcohol-related harm. Alcohol taxes are an effective public health measure as they raise prices and suppress demand. However, if they do not keep pace with both inflation and incomes, alcohol products will become more affordable over time. This has been the case in the UK. Deep discounting by retailers has also driven down the price of alcohol and encouraged heavy drinkers to maintain dangerous levels of consumption. These problems need to be tackled by a combinati on of more effective fiscal policy and controls on pricing and discounting. Alcohol products are an extraordinary anomaly. Unlike most food products, they are both remarkably harmful and excepti onally lightly regulated. As with other toxic products, the product label ought to communicate the content of the product and the risks of its consumpti on. Regulation should drive out products that appeal to young people while also incentivising the development and sale of lower strength products. The pervasive marketing of alcohol products in the UK is indefensible. Current restrictions are woefully inadequate: children and young people are regularly exposed to alcohol adverti sing in both old and new media. Only a complete ban on all alcohol advertising and sponsorship will make a lasting diff erence. Licensing practice in the UK is out of date. The focus on pubs and bars has allowed shops and supermarkets to become the dominant players in alcohol sales. Consequently, alcohol is now more available than it has ever been. This has driven pre-loading: getting drunk on cheap, shop-bought alcohol before heading out to late-opening night life. Licensing must focus on public health and seek to control the overall availability of alcohol as well as the effects of drunkenness. Beyond these populati on-level approaches, many more targeted measures are needed to reduce alcohol-related harm. Early interventi on by health and social care professionals is an important and underexploited opportunity to prevent problems developing. Stronger drink driving measures are also required. All these measures are needed. Together, they provide a template for an integrated and comprehensive strategy to tackle the harm from alcohol in the UK.Additional co-authors: Gerry McElwee, Dr Kieran Moriarty CBE, Dr Robin Purshouse, Dr Peter Rice, Alison Rogers, George Roycroft , Chit Selvarajah, Don Shenker, Eric Appleby, Dr Nick Sheron, and Colin Shevill

Atomic Force Microscopy: Imaging with Electrical Double Layer Interactions

International audienc

Novel pH-Responsive Cubosome and Hexosome Lipid Nanocarriers of SN-38 Are Prospective for Cancer Therapy

pH-responsive nanoparticles enable the selective delivery of a chemotherapeutic agent to tumours while reducing adverse effects. Herein we synthesised four novel aminolipids and developed pH-responsive nanostructured lipid nanoparticles (LNP), which exhibited a slow-releasing hexagonal structure (H2) at physiological pH and quick release bicontinuous cubic phase (Q2) at the acidic tumour pH. The nanoparticles were used to encapsulate and control the release of the chemotherapeutic agent SN-38. High-throughput formulation techniques were employed to fabricate LNP by mixing various amounts of aminolipid with monoolein (MO). The effect of aminolipids on MO self-assembled structures was studied using small-angle X-ray scattering (SAXS) at various pH values. Out of the four studied aminolipid-MO LNP systems, the nanoparticles containing N-(Pyridin-4-ylmethyl) oleamide (OAPy-4) or N-(2(piperidin-1yl)ethyl) oleamide (OAPi-1) exhibited a pH-induced H2 to Q2 phase transition in a tumour-relevant pH range (pH 5.5–7.0). SN-38 is 1000 times more efficacious than the commercially available prodrug irinotecan. However, low solubility in water and instability at physiological pH makes it unsuitable for clinical use. SN-38 was loaded into LNP containing MO and aminolipid OAPy-4. The drug loading and entrapment efficiency were determined, and the results indicated that the aqueous solubility of SN-38 loaded in LNP dispersions was ~100 times higher compared to the solubility of the pure drug in aqueous solution. Furthermore, we demonstrated that the in vitro SN-38 release rate from LNPs was faster at lower pH (pH 5) than at neutral pH. Therefore, pH-responsive LNPs developed in this study can potentially be employed in delivering and controlling the release of the potent drug SN-38 to tumour sites

Chelating DTPA amphiphiles: Ion-tunable self-assembly structures and gadolinium complexes

A series of chelating amphiphiles and their gadolinium (Gd(iii)) metal complexes have been synthesized and studied with respect to their neat and lyotropic liquid crystalline phase behavior. These amphiphiles have the ability to form ion-tunable self-assembly nanostructures and their associated Gd III complexes have potential as magnetic resonance imaging (MRI) contrast enhancement agents. The amphiphiles are composed of diethylenetriaminepentaacetic acid (DTPA) chelates conjugated to one or two oleyl chain(s) (DTPA-MO and DTPA-BO), or isoprenoid-type chain(s) of phytanyl (DTPA-MP and DTPA-BP). The thermal phase behavior of the neat amphiphiles was examined by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and cross polarizing optical microscopy (POM). Self-assembly of neat amphiphiles and their associated Gd complexes, as well as their lyotropic phase behavior in water and sodium acetate solutions of different ionic strengths, were examined by POM and small and wide angle X-ray scattering (SWAXS). All neat amphiphiles exhibited lamellar structures. The non-complexed amphiphiles showed a variety of lyotropic phases depending on the number and nature of the hydrophobic chain in addition to the ionic state of the hydration. Upon hydration with increased Na-acetate concentration and the subtle changes in the effective headgroup size, the interfacial curvature of the amphiphile increased, altering the lyotropic liquid crystalline structures towards higher order mesophases such as the gyroid (Ia3d) bicontinuous cubic phase. The chelation of Gd with the DTPA amphiphiles resulted in lamellar crystalline structures for all the neat amphiphiles. Upon hydration with water, the Gd-complexed mono-conjugates formed micellar or vesicular self-assemblies, whilst the bis-conjugates transformed only partially into lyotropic liquid crystalline mesophases