Amphiphilic dextran/magnetite nanocomposites as magnetic resonance imaging probes

Versatile Types of Polysaccharide-Based Drug Delivery Systems: From Strategic Design to Cancer Therapy

Chemotherapy is still the most direct and effective means of cancer therapy nowadays. The proposal of drug delivery systems (DDSs) has effectively improved many shortcomings of traditional chemotherapy drugs. The technical support of DDSs lies in their excellent material properties. Polysaccharides include a series of natural polymers, such as chitosan, hyaluronic acid, and alginic acid. These polysaccharides have good biocompatibility and degradability, and they are easily chemical modified. Therefore, polysaccharides are ideal candidate materials to construct DDSs, and their clinical application prospects have been favored by researchers. On the basis of versatile types of polysaccharides, this review elaborates their applications from strategic design to cancer therapy. The construction and modification methods of polysaccharide-based DDSs are specifically explained, and the latest research progress of polysaccharide-based DDSs in cancer therapy are also summarized. The purpose of this review is to provide a reference for the design and preparation of polysaccharide-based DDSs with excellent performance.

Design of Functional Magnetic Nanocomposites for Bioseparation

Magnetic materials have been widely used in bioseparation in recent years due to their good biocompatibility, magnetic properties, and high binding capacity. In this review, we provide a brief introduction on the preparation and bioseparation applications of magnetic materials including the synthesis and surface modification of magnetic nanoparticles as well as the preparation and applications of magnetic nanocomposites in the separation of proteins, peptides, cells, exosomes and blood. The current limitations and remaining challenges in the fabrication process of magnetic materials for bioseparation will be also detailed.

Maghemite Nanoparticles with Enhanced Magnetic Properties: One-Pot Preparation and Ultrastable Dextran Shell

In the field of nanomedicine, superparamagnetic nanoparticles are one of the most studied nanomaterials for theranostics. In this study, a one-pot synthesis of magnetic nanoparticles is presented, with an increased control on particle size from 10 to 40 nm. Monitoring of vacuum level is introduced here as a crucial parameter for achieving a fine particle morphology. The magnetic properties of these nanoparticles are highly affected by disorders or mismatches in crystal structure. A prolonged oxidation step is applied to the obtained nanoparticles to transform the magnetic phases into a pure maghemite one, confirmed by high-resolution X-ray photoelectron spectroscopy analysis, by Mössbauer spectrometry and, indirectly, by increased performances in magnetization curves and in relaxation times. Afterward, the attained nanoparticles are transferred into water by a nonderivatized dextran coating. Thermogravimetric analysis confirms that polysaccharide molecules replace oleic acid on the surface by stabilizing the particles in the aqueous phase and culture media. Preliminary in vitro test reveals that the dextran-coated nanoparticles are not passively internalized from the cells. As a proof of concept, a secondary layer of chitosan assures a positive charge to the nanoparticle surface, thus enhancing cellular internalization.

Multivalent manganese complex decorated amphiphilic dextran micelles as sensitive MRI probes

T₁ contrast agents based on Mn(II) were conjugated on amphiphilic dextran micelles via click chemistry. The obtained paramagnetic nanomicelle contrast agent has a higher T₁ relaxivity (13.3 Mn mmol^-1 s^-1) and better sensitivity than those of free Mn(II) complexes. Studies carried out in vivo suggest that this contrast agent has a better and long-acting vascular enhancement effect at a lower manganese dosage (0.1 Mn mmol kg^-1 BW).

Layer-by-layer capsules for magnetic resonance imaging and drug delivery

Layer-by-layer (LbL) self-assembled polyelectrolyte capsules have demonstrated their unique advantages and capability in drug delivery applications. These ordered micro/nano-structures are also promising candidates as imaging contrast agents for diagnostic and theranostic applications. Magnetic resonance imaging (MRI), one of the most powerful clinical imaging modalities, is moving forward to the molecular imaging field and requires the availability of advanced imaging probes. In this review, we are focusing on the design of MRI visible LbL capsules, which incorporate either paramagnetic metal-ligand complexes or superparamagnetic iron oxide (SPIO) nanoparticles. The design criteria cover the topics of probe sensitivity, biosafety, long-circulation property, targeting ligand decoration, and drug loading strategies. Examples of MRI visible LbL capsules with paramagnetic or superparamagnetic moieties were given and discussed. This carrier platform can also be chosen for other imaging modalities.