Replacing the Rhamnose-Xylose Moiety of QS-21 with Simpler Terminal Disaccharide Units Attenuates Adjuvant Activity in Truncated Saponin Variants

Adjuvants are key immunostimulatory components in vaccine formulations, which improve the immune response to the co-administered antigen. The saponin natural product QS-21 is one of the most promising immunoadjuvants in the development of vaccines against cancer and infectious diseases but suffers from limitations that have hampered its widespread human use. Previous structure–activity relationship studies have identified simplified saponin variants with truncated carbohydrate chains, but have not focused on the influence of the linear oligosaccharide domain of QS-21 in adjuvant activity. Herein, an expeditious 15-step synthesis of new linear trisaccharide variants of simplified QS-21-derived adjuvants is reported, in which the complex terminal xylose-rhamnose moiety has been replaced with commercially available, simpler lactose and cellobiose disaccharides in a β-anomeric configuration. In vivo immunological evaluation of the synthetic saponins showed attenuated antibody responses, highlighting the negative impact of such carbohydrate modifications on adjuvant activity, which could be associated with higher saponin conformational flexibility.     

A review of bacterial cellulose: sustainable production from agricultural waste and applications in various fields

Bacterial cellulose (BC) is a polymer with interesting conformation and properties. BC can be obtained in different shapes and is easily modified by chemical and physical means, so its applications in the production of new materials and nanocomposites for different purposes have been in the focus of many research projects. However, one of the major challenges to address in bacterium-derived polymer technology is to find suitable carbon sources as substrates that are cheap and do not compete with food production for achieving large scale industrial applications. Agricultural wastes are defined as the residues from the growing and processing of raw agricultural products such as crops, fruits, vegetables and dairy products. Their composition can vary depending on the type of agricultural activity and harvesting conditions, but these residues are suitable for the production of BC. The aim of this review is to give insight into the production of BC using agro-wastes and an overview of the most interesting and novel applications of this biopolymer in different areas i.e. environmental applications, optoelectronic and conductive devices, food ingredients and packaging, biomedicine, and 3D printing technology.

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By-products of the cider production: an alternative source of nutrients to produce bacterial cellulose

In the present work a culture process to produce bacterial cellulose (BC) using by-products of the cider production from the Basque Country was investigated. The apple pomace was mixed with sugar cane (AR/SC medium) and the mixture was found to be a potential carbon source for Gluconacetobacter medellinensis strain ID13488 since higher cellulose production was observed with respect to the commercial Hestrin and Shramm medium (H–S). The culture media were characterized in terms of pH, oxygen and sugars consumption. The expression level of the operon bcs (genes involved in BC biosynthesis) in apple residue containing medium respect to standard H–S medium was determined. It was found that in AR/SC medium the expression levels of bcsA gene, wich is the first gene of the bcs operon, was increased in 1.5-fold respect to the H–S media which correlates with the fact that BC production in AR/SC media is higher than in H–S media. The physico-chemical and mechanical properties, microstructure, crystallinity and water holding capacity of the biosynthesized BC membranes were analyzed and it was found that, in general, the BC obtained from AR/SC medium presented superior properties than that obtained from H–S medium. In this study an economic method for BC production is proposed with suitable properties for many applications.     

Crystallinity and Crystalline Confinement of the Amorphous Phase in Polylactides

Summary: Stereorregular polylactides such as poly (L-lactide) (PLLA) or poly (D-lactide) result from polymerization of optically pure lactides and are semicrystalline. Optically non-active poly(D,L-lactide) (PDLLA) can be regarded as random or atactic copolymers, show a random moiety distribution, and are completely amorphous. In this work three phases, comprising mobile amorphous fraction (MAF, χ_MA), rigid amorphous fraction (RAF, χ_RA) and crystalline fraction (χ_c) were determined in PLLA. It will be shown that RAP fraction not only elevates Tg but also increases the dynamic fragility (m) of polylactide chains around the Tg. These results agree with reported cases in which topologycal constraints inhibit longer range dynamics and suggest a smaller length scale of cooperativity of chains in confined environments.     

In‐situ spectroscopic assessment of the conservation state of building materials from a Palace house affected by infiltration water

The built Heritage constantly suffers different deterioration processes caused by the action of external agents, being one of the main consequences of the formation of soluble salts. These salts appear as efflorescences or subefflorescences that by hydration and dehydration cycles and/or dissolution processes producing crystallization of salts within the pores may promote internal fractures and material loss. The assessment of building material conservation on a 15^th century Palace house, located close to the Urola river (Azpeitia, Basque Country, North of Spain), has been performed by in‐situ characterization of pathologies on sandstone, mortar and limestone affected by infiltration waters. Portable Raman and X‐ray fluorescence spectrometers have been used to characterize the bulk materials as well as the salts present along the different walls of the Palace. The in‐situ analysis by those portable equipments has been complemented with laboratory measurements on selected samples, taken close to the spots analysed by the portable instruments. Different carbonates (natrite, termonatrite, natron, calcite and gaylussite), oxides (hematite, limonite and rutile), feldspar (orthoclase) and silicates (quartz) have been identified as original compounds. Furthermore, nitrates (niter, nitrocalcite and nitratine) and sulphates (gypsum and thenardite) have been found as decaying compounds permitting to establish the degradation processes of the attack produced by the infiltration waters on the different building materials. Moreover, the study revealed that certain materials used in a previous restoration produced new degradation processes, evidencing the importance of a proper selection of the materials to be used in the interventions. Copyright © 2013 John Wiley & Sons, Ltd.     

A conventional an 2DCOS infrared approach to the kinetics of protein misfolding

Cell viability depends on the correct folding of the proteins involved in metabolism. Proteins are synthesized on the endoplasmic reticulum and must follow a pathway to a correct, metastable, tridimensional structure. Changes in structure or in environmental conditions can drive an instability of the folding conditions and produce non-active aggregates that in principle are proteolysed by the cellular mechanisms. However, these aggregates can be even more stable than the native proteins, escaping the cellular control. They can be classified as amorphous, if there is not a well-organized structural pattern, or ordered if a repetitive pattern is produced. These ordered structures, known as fibrils, are involved in many diseases. Infrared spectroscopy is a method of choice to study its formation because it is not affected by turbidity or the formation of high molecular weight aggregates. Moreover, in both cases, two bands characteristic of intermolecular β-sheets allow the monitoring of the aggregate formation. In both cases, the appearance of these bands involves a non-reversible path in protein folding. It has been suggested that a difference in the ordered structures involves an increasing in band intensity. This change can be the origin in variations on the 2DCOS maps. The synchronous map gives an overall idea of the process involved. The asynchronous is more informative because reflects the kinetic changes produced. The outcome of both processes, amorphous or ordered is that 2DCOS can provide a further insight to the knowledge of the kinetic processes giving rise to aggregated structures. This outcome could consist on the order in which the different secondary structures are prone to form the aggregates.