Omicron - The new SARS-CoV-2 challenge?

SARS-CoV-2 virus has infected nearly 300 M people worldwide and has been associated with over 6 M deaths by March 2022. Since the virus emergence in December 2019 in Wuhan, several new mutations have been described. The World Health Organization has developed a working name for these emerging variants according to their impact on the worldwide population. In this context a high alert has been paid to variants of concern (VOC) due to their high infectiousness and transmissibility patterns. The most recent VOC, Omicron (B.1.1.529), has become dominant in the shortest time ever and has placed Europe under an overwhelming and unprecedented number of new cases. This variant has numerous mutations in regions that are associated with higher transmissibility, stronger viral binding, affinity and antibody escape. Moreover, the mutations and deletions present in the spike protein suggest that the SARS-CoV-2 specific attachment inhibitors may not be the best option for Omicron therapy. Omicron is the dominant variant circulating worldwide and, at the end of February 2022, it was responsible for nearly all sequences reported to GISAID. Omicron is made up of several sublineages, where the most common are BA.1 and BA.2 (or Nextstrain clade 21K and 21L, respectively). At a global level, it is possible to say that the proportion of BA.2 has been increasing relative to BA.1 and in some countries it has been replacing it at high rates. In order to better assess the Omicron effectiveness on antibody escape, spread and infectious ability it is of the highest relevance to maintain a worldwide tight surveillance. Even though this variant has been associated with a lower death rate, it is important to highlight that the number of people becoming infected is concerning and that further unpredictable mutations may emerge as the number of infected people rises.

Biosensors as diagnostic tools in clinical applications.

Nowadays, the development of new technological solutions in the medical field, in particular biosensors, is a priority and a ground for great scientific and financial investment. From glucose sensors to highly sensible and more precise molecular tools, this biotechnological field has gone through an exponential growth, but still the applications are very limited to the future potential foreseen in the medical area. In the last decade, the advances in the genomic field have permitted the identification of specific biomarkers related to certain diseases, becoming one of the main approaches used in clinical diagnosis. Biomarkers have different clinical values, in the sense that they may provide preventive, predictive, prognostic and therapeutic response related information, not being exclusively used for diagnostic purposes, but also be applied in health management and disease treatment. Therefore, biomarkers allied with biosensors have the potential to revolutionize the way healthcare is managed. The vast choice of bioreceptors such as nucleic acids, antibodies, antigens, enzymes and even whole cells, consents the diagnosis of diseases ranging from viral and bacterial infections to cancer and metabolism disorders. The major appeal of these sensing platforms is that it provides a fast, cost-effective, reliable, highly sensitive and easy way to obtain an earlier clinical diagnosis, which can significantly affect the survival rate or patient's prognosis. This review will explore some of the most recent devices available and its clinical applications.

Molecular cloning of TaMATE2 homoeologues potentially related to aluminium tolerance in bread wheat (Triticum aestivum L.).

Recently, members of the MATE family have been implicated in aluminium (Al) tolerance by facilitating citrate efflux in plants. The aim of the present work was to perform a molecular characterisation of the MATE2 gene in bread wheat. Here, we cloned a member of the MATE gene family in bread wheat and named it TaMATE2, which showed the typical secondary structure of MATE-type transporters maintaining all the 12 transmembrane domains. Amplification in Chinese Spring nulli-tetrasomic and ditelosomic lines revealed that TaMATE2 is located on the long arm of homoeologous group 1 chromosomes. The transcript expression of TaMATE2 homoeologues in two diverse bread wheat genotypes, Barbela 7/72/92 (Al-tolerant) and Anahuac (Al-sensitive), suggested that TaMATE2 is expressed in both root and shoot tissues of bread wheat, but mainly confined to root rather than shoot tissues. A time-course analysis of TaMATE2 homoeologue transcript expression revealed the Al responsive expression of TaMATE2 in root apices of the Al-tolerant genotype, Barbela 7/72/92. Considering the high similarity of TaMATE2 together with similar Al responsive expression pattern as of ScFRDL2 from rye and OsFRDL2 from rice, it is likely that TaMATE2 also encodes a citrate transporter. Furthermore, the TaMATE2-D homoeologue appears to be near the previously reported locus (wPt0077) on chromosome 1D for Al tolerance. In conclusion, molecular cloning of TaMATE2 homoeologues, particularly TaMATE2-D, provides a plausible candidate for Al tolerance in bread wheat that can be used for the development of more Al-tolerant cultivars in this staple crop.

A novel lipid nanocarrier for insulin delivery: production, characterization and toxicity testing.

A novel nanocarrier based on solid lipid nanoparticles (SLNs) was developed for insulin delivery using a novel double emulsion method. Physical stability of particles was assessed by size analysis using dynamic light scattering (DLS), matrix crystallinity by differential scanning calorimetry (DSC) and toxicity analysis by Drosophila melanogaster testing. Insulin-SLNs were composed of Softisan®100 1.25% wt, Lutrol®F68 1% wt, soybean lecithin 0.125% wt, and loaded with 0.73-0.58 mg/mL peptide. Placebo-SLNs (insulin-free) also contained 0.025% wt Tween®80. Mean particle sizes of placebo-SLN and insulin-SLN were 958 ± 9.5 and 978 ± 8.3 nm, respectively. The polydispersity index (PI) was 0.28 ± 0.018 and 0.29 ± 0.013, respectively. Polarized light microscopy analysis depicted no aggregation of developed particles. DSC analysis allowed characterizing SLN with 43-51% matrix crystallinity. Using Drosophila melanogaster test, no toxicity was reported for SLN and for the bulk lipid. This study shows that SLNs are promising and helpful to overcome conventional insulin therapy, in particular for their lack of toxicity for oral delivery.

Modified Rose Bengal assay for surface hydrophobicity evaluation of cationic solid lipid nanoparticles (cSLN).

Surface hydrophobicity of nanocarriers influences protein binding and subsequently fate of nanoparticles in blood circulation. Therefore, characterization of surface hydrophobicity of nanocarriers provides important preclinical information. Here, a modified classical adsorption method for the needs of characterization of cationic solid lipid nanoparticles (cSLN) was developed. We have identified possible method limitations that should be considered when performing the analysis, i.e. the problems associated with particle separation from the dispersion and their own absorbance in visible spectrum. We propose two modified methods for performing the assay overcoming the stated limitations. We also discuss here evaluation by different approaches (calculation of binding constants or partitioning quotient) and their suitability for the prepared cSLN formulation. Overall, we confirmed that our modified adsorption method can provide useful information about surface properties of (cationic) SLN, however, performing and evaluation of the assay need special attention in order to obtain the desired results.

Cationic solid lipid nanoparticles (cSLN): structure, stability and DNA binding capacity correlation studies.

Cationic solid lipid nanoparticles (cSLN) are promising lipid nanocarriers for intracellular gene delivery based on well-known and widely accepted materials. cSLN containing single-chained cationic lipid cetyltrimethylammonium bromide were produced by high pressure homogenization and characterized in terms of (a) particle size distribution by photon correlation spectroscopy (PCS) and laser diffractometry (LD), (b) thermal behaviour using differential scanning calorimetry (DSC) and (c) the presence of various polymorphic phases was confirmed by X-ray diffraction (WAXD). SLN composed of Imwitor 900P (IMW) showed different pDNA stability and binding capacity in comparison to those of Compritol 888 ATO (COM). IMW-SLN, having z-ave=138-157 nm and d(0.5)=0.15-0.158 µm could maintain this size for 14 days at room temperature. COM-SLN had z-ave=334 nm and d(0.5)=0.42 µm on the day of production and could maintain similar size during 90 days. IMW-SLN revealed improved pDNA binding capacity. We attempted to explain these differences by different interactions between the solid lipid and the tested cationic lipid.

Nanoparticulate carriers (NPC) for oral pharmaceutics and nutraceutics.

The introduction of nanoparticulate carriers (NPC) in the pharmaceutic and nutraceutic fields has changed the definitions of disease management and treatment, diagnosis, as well as the supply food chain in the agri-food sector. NPC composed of synthetic polymers, proteins or polysaccharides gather interesting properties to be used for oral administration of pharmaceutics and nutraceutics. Oral administration remains the most convenient way of delivering drugs (e.g. peptides, proteins and nucleic acids) since these suffer similar metabolic pathways as food supply. Recent advances in biotechnology have produced highly potent new molecules however with low oral bioavailability. A suitable and promising approach to overcome their sensitivity to chemical and enzymatic hydrolysis as well as the poor cellular uptake, would be their entrapment within suitable gastrointestinal (GI) resistant NPC. Increasing attention has been paid to the potential use of NPC for peptides, proteins, antioxidants (carotenoids, omega fatty acids, coenzyme Q10), vitamins, probiotics, for oral administration. This review focuses on the most important materials to produce NPC for oral administration, and the most recent achievements in the production techniques and bioactives successfully delivered by these means.