In situ synthesis of Fe3O4 nanoparticles coated by chito-oligosaccharides: physico-chemical characterizations and cytotoxicity evaluation for biomedical applications

Application of magnetism in tissue regeneration: recent progress and future prospects

Tissue regeneration is a hot topic in the field of biomedical research in this century. Material composition, surface topology, light, ultrasonic, electric field and magnetic fields (MFs) all have important effects on the regeneration process. Among them, MFs can provide nearly non-invasive signal transmission within biological tissues, and magnetic materials can convert MFs into a series of signals related to biological processes, such as mechanical force, magnetic heat, drug release, etc. By adjusting the MFs and magnetic materials, desired cellular or molecular-level responses can be achieved to promote better tissue regeneration. This review summarizes the definition, classification and latest progress of MFs and magnetic materials in tissue engineering. It also explores the differences and potential applications of MFs in different tissue cells, aiming to connect the applications of magnetism in various subfields of tissue engineering and provide new insights for the use of magnetism in tissue regeneration.

Comparative Evaluation of the In Vitro Cytotoxicity of a Series of Chitosans and Chitooligosaccharides Water-Soluble at Physiological pH

Chitosans (CS) have been of great interest due to their properties and numerous applications. However, CS have poor solubility in neutral and basic media, which limits their use in these conditions. In contrast, chitooligosaccharides (COS) have better solubility in water and lower viscosity in aqueous solutions whilst maintaining interesting biological properties. CS and COS, unlike other sugars, are not single polymers with a defined structure but are groups of molecules with modifiable structural parameters, allowing the adaptation and optimization of their properties. The great versatility of CS and COS makes these molecules very attractive for different applications, such as cryopreservation. Here, we investigated the effect of the degree of polymerization (DP), degree of N-acetylation (DA) and concentration of a series of synthesized CS and COS, water-soluble at physiological pH, on their cytotoxicity in an L929 fibroblast cell culture. Our results demonstrated that CS and COS showed no sign of toxicity regarding cell viability at low concentrations (≤10 mg/mL), independently of their DP and DA, whereas a compromising effect on cell viability was observed at a high concentration (100 mg/mL).

In vivo Biodistribution and Clearance of Magnetic Iron Oxide Nanoparticles for Medical Applications

Magnetic iron oxide nanoparticles (magnetite and maghemite) are intensively studied due to their broad potential applications in medical and biological sciences. Their unique properties, such as nanometric size, large specific surface area, and superparamagnetism, allow them to be used in targeted drug delivery and internal radiotherapy by targeting an external magnetic field. In addition, they are successfully used in magnetic resonance imaging (MRI), hyperthermia, and radiolabelling. The appropriate design of nanoparticles allows them to be delivered to the desired tissues and organs. The desired biodistribution of nanoparticles, eg, cancerous tumors, is increased using an external magnetic field. Thus, knowledge of the biodistribution of these nanoparticles is essential for medical applications. It allows for determining whether nanoparticles are captured by the desired organs or accumulated in other tissues, which may lead to potential toxicity. This review article presents the main organs where nanoparticles accumulate. The sites of their first uptake are usually the liver, spleen, and lymph nodes, but with the appropriate design of nanoparticles, they can also be accumulated in organs such as the lungs, heart, or brain. In addition, the review describes the factors affecting the biodistribution of nanoparticles, including their size, shape, surface charge, coating molecules, and route of administration. Modern techniques for determining nanoparticle accumulation sites and concentration in isolated tissues or the body in vivo are also presented.

Highly efficient nanocomposites based on molecularly imprinted magnetic covalent organic frameworks for selective extraction of bisphenol A from liquid matrices

Highly efficient nanocomposites, hydrophobic molecularly imprinted magnetic covalent organic frameworks (MI-MCOF), have been farbricated by a facile Schiff-base reaction. The MI-MCOF was based on terephthalaldehyde (TPA) and 1,3,5-tris(4-aminophenyl) benzene (TAPB) as functional monomer and crosslinker, anhydrous acetic acid as catalyst, bisphenol AF as dummy template, and NiFe₂O₄ as magnetic core. This organic framework significantly reduced the time consumption of conventional imprinted polymerization and avoided the use of traditional initiator and cross-linking agents. The synthesized MI-MCOF exhibited superior magnetic responsivity and affinity, as well as high selectivity and kinetics for bisphenol A (BPA) in water and urine samples. The equilibrium adsorption capacity (Q_e) of BPA on the MI-MCOF was 50.65 mg g^-1, which was 3-7-fold higher than of its three structural analogues. The imprinting factor of BPA reached up to 3.17, and the selective coefficients of three analogues were all > 2.0, evidencing the excellent selectivity of fabricated nanocomposites to BPA. Based on the MI-MCOF nanocomposites, the magnetic solid-phase extraction (MSPE), combined with HPLC and fluorescence detection (HPLC-FLD), offered superior analytical performance: wide linear range of 0.1-100 μg L^-1, high correlation coefficient of 0.9996, low limit of detection of 0.020 μg L^-1, good recoveries of 83.5-110%, and relative standard deviations (RSDs) of 0.5-5.7% in environmental water, beverage, and human urine samples. Consequently, the MI-MCOF-MSPE/HPLC-FLD method provides a good prospect in selective extraction of BPA from complex matrices while replacing traditional magnetic separation and adsorption materials.