Advances in Chitosan-Based CRISPR/Cas9 Delivery Systems.

Clustered regularly interspaced short palindromic repeat (CRISPR) and the associated Cas endonuclease (Cas9) is a cutting-edge genome-editing technology that specifically targets DNA sequences by using short RNA molecules, helping the endonuclease Cas9 in the repairing of genes responsible for genetic diseases. However, the main issue regarding the application of this technique is the development of an efficient CRISPR/Cas9 delivery system. The consensus relies on the use of non-viral delivery systems represented by nanoparticles (NPs). Chitosan is a safe biopolymer widely used in the generation of NPs for several biomedical applications, especially gene delivery. Indeed, it shows several advantages in the context of gene delivery systems, for instance, the presence of positively charged amino groups on its backbone can establish electrostatic interactions with the negatively charged nucleic acid forming stable nanocomplexes. However, its main limitations include poor solubility in physiological pH and limited buffering ability, which can be overcome by functionalising its chemical structure. This review offers a critical analysis of the different approaches for the generation of chitosan-based CRISPR/Cas9 delivery systems and suggestions for future developments.

Overcoming the protein corona in chitosan-based nanoparticles.

Numerous properties of chitosan have led to its extensive use in the formulation of nanomaterials for drug delivery. However, the cationic surface of chitosan-based nanoparticles adsorbs proteins upon exposure to biological fluids, forming a phenomenon known as 'protein corona'. This causes several effects such as decreased bioavailability and limited in vivo clinical applications of chitosan nanoparticles. Understanding and overcoming the effects of protein adsorption on chitosan nanoparticles is key for drug delivery purposes. This review focuses on the strategies implemented to increase the stability of chitosan nanoparticles in the systemic circulation by averting the formation of protein corona and the limitations of PEGylation.

Biomedical and Pharmacological Uses of Fluorescein Isothiocyanate Chitosan-Based Nanocarriers.

Chitosan-based nanocarriers (ChNCs) are considered suitable drug carriers due to their ability to encapsulate a variety of drugs and cross biological barriers to deliver the cargo to their target site. Fluorescein isothiocyanate-labeled chitosan-based NCs (FITC@ChNCs) are used extensively in biomedical and pharmacological applications. The main advantage of using FITC@ChNCs consists of the ability to track their fate both intra and extracellularly. This journey is strictly dependent on the physico-chemical properties of the carrier and the cell types under investigation. Other applications make use of fluorescent ChNCs in cell labeling for the detection of disorders in vivo and controlling of living cells in situ. This review describes the use of FITC@ChNCs in the various applications with a focus on understanding their usefulness in labeled drug-delivery systems.

Overcoming the Blood-Brain Barrier: Functionalised Chitosan Nanocarriers.

The major impediment to the delivery of therapeutics to the brain is the presence of the blood-brain barrier (BBB). The BBB allows for the entrance of essential nutrients while excluding harmful substances, including most therapeutic agents; hence, brain disorders, especially tumours, are very difficult to treat. Chitosan is a well-researched polymer that offers advantageous biological and chemical properties, such as mucoadhesion and the ease of functionalisation. Chitosan-based nanocarriers (CsNCs) establish ionic interactions with the endothelial cells, facilitating the crossing of drugs through the BBB by adsorptive mediated transcytosis. This process is further enhanced by modifications of the structure of chitosan, owing to the presence of reactive amino and hydroxyl groups. Finally, by permanently binding ligands or molecules, such as antibodies or lipids, CsNCs have showed a boosted passage through the BBB, in both in vivo and in vitro studies which will be discussed in this review.

Fluorescein Isothiocyanate Chitosan Nanoparticles in Oral Drug Delivery Studies.

Oral administration of drugs is one of the most patient-friendly drug delivery routes. However, drug bioavailability via the oral route remains poor due to the harsh gastrointestinal environment. In recent years, many nanocarriers have been designed to overcome this limitation. Among those, chitosan nanoparticles (ChNPs) have proved to be a quite popular choice. Here, we highlight the use of fluorescein isothiocyanate-tagged ChNPs as an invaluable tool to monitor the fate of ChNPs encapsulating oral drugs, leading to an in-depth understanding of drug biodistribution and, in turn, shedding light on ways to improve bioavailability.

A Urea Potentiometric Biosensor Based on a Thiophene Copolymer.

A potentiometric enzyme biosensor is a convenient detector for quantification of urea concentrations in industrial processes, or for monitoring patients with diabetes, kidney damage or liver malfunction. In this work, poly(3-hexylthiophene-co-3-thiopheneacetic acid) (P(3HT-co-3TAA)) was chemically synthesized, characterized and spin-coated onto conductive indium tin oxide (ITO) glass electrodes. Urease (Urs) was covalently attached to the smooth surface of this copolymer via carbodiimide coupling. The electrochemical behavior and stability of the modified Urs/P(3HT-co-3TAA)/ITO glass electrode were investigated by cyclic voltammetry, and the bound enzyme activity was confirmed by spectrophotometry. Potentiometric response studies indicated that this electrode could determine the concentration of urea in aqueous solutions, with a quasi-Nernstian response up to about 5 mM. No attempt was made to optimize the response speed; full equilibration occurred after 10 min, but the half-time for response was typically <1 min.

Age-dependent expression of VEGFR2 in deep brain arteries in small vessel disease, CADASIL, and healthy brains.

Vascular myocytes are central to brain aging. Small vessel disease (SVD; arteriolosclerosis) is a widespread cause of lacunar stroke and vascular dementia and is characterized by fibrosis and depletion of vascular myocytes in small penetrating arteries. Vascular endothelial growth factor (VEGF) is associated with brain aging, and Immunolabeling for vascular endothelial growth factor receptor 2 (VEGFR2) is a potent determinant of cell fate. Here, we tested whether VEGFR2 in vascular myocytes is associated with older age and SVD in human brain. Immunolabeling for VEGFR2 in deep gray matter was assessed in older people with or without moderate-severe SVD or in younger people without brain pathology or with a monogenic form of SVD (Cerebral Autosomal-Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy). All cases were without Alzheimer's disease pathology. Myocyte VEGFR2 was associated with increasing age (p = 0.0026) but not with SVD pathology or with sclerotic index or blood vessel density. We conclude that VEGFR2 is consistently expressed in small artery myocytes of older people and may mediate effects of VEGF on brain vascular aging.

Side-chain liquid crystal conducting polymers.

This article overviews some of the research progress on the effects of incorporating liquid crystalline functionalities into commercial conjugated polymers such as polythiophene, polypyrrole and polyaniline. Polarisable aromatic mesogens are generally attached via a flexible spacer group to the monomers to form a side-chain. Consequently, the selforganising properties of liquid crystals can be used to influence the conducting polymer backbone and control the electrical, magnetic and mechanical properties of the material. Some applications of these interesting materials are discussed.

Principles and prospects of high-energy magnesium-ion batteries.

In the last decade or so, lithium batteries have gained important niche positions in the market for electrochemical storage systems. Their energy capacities per unit weight (or volume) are remarkably better than those of traditional batteries--yet they appear to be approaching their practical limit, and alternative cell systems are under active investigation. The potential advantages of replacing lithium by magnesium have long been recognised, but for years it was thought that materials limitations and technical problems would prevent them from being realised. However, a combination of commercial pressures and recent scientific breakthroughs has made it likely that magnesium batteries will soon be available for a wide range of applications; they are expected to be cheaper and safer than those based on lithium, with comparable performance. This article briefly reviews the current situation and looks at the general background, principles and cell components, outlining some of the technical problems and discussing some promising materials for magnesium-ion batteries.