Nanomaterials engineering for drug delivery: a hybridization approach

Agarose-based biomaterials for tissue engineering

Agarose is a natural polysaccharide polymer having unique characteristics that give reason to consider it for tissue engineering applications. Special characteristics of agarose such as its excellent biocompatibility, thermo-reversible gelation behavior and physiochemical features support its use as a biomaterial for cell growth and/or controlled/localized drug delivery. The resemblance of this natural carbohydrate polymer to the extracellular matrix results in attractive features that bring about a strong interest in its usage in the field. The scope of this review is to summarize the extensive researches addressing agarose-based biomaterials in order to provide an in-depth understanding of its tissue engineering-related applications.

A facile route to the synthesis of anilinic electroactive colloidal hydrogels for neural tissue engineering applications

An innovative drug-loaded colloidal hydrogel was synthesized for applications in neural interfaces in tissue engineering by reacting carboxyl capped aniline dimer and gelatin molecules. Dexamethasone was loaded into the gelatin-aniline dimer solution as a model drug to form an in situ drug-loaded colloidal hydrogel. The conductivity of the hydrogel samples fluctuated around 10-5 S/cm which appeared suitable for cellular activities. Cyclic voltammetry was used for electroactivity determination, in which 2 redox states were observed, suggesting that the short chain length and steric hindrance prevented the gel from achieving a fully oxidized state. Rheological data depicted the modulus decreasing with aniline dimer increment due to limited hydrogen bonds accessibility. Though the swelling ratio of pristine gelatin (600%) decreased by the introduction and increasing the concentration of aniline dimer because of its hydrophobic nature, it took the value of 300% at worst, which still seems promising for drug delivery uses. Degradation rate of hydrogel was similarly decreased by adding aniline dimer. Drug release was evaluated in passive and stimulated patterns demonstrating tendency of aniline dimer to form a vesicle that controls the drug release behavior. The optimal cell viability, proper cell attachment and neurite extension was achieved in the case of hydrogel containing 10 wt% aniline dimer. Based on tissue/organ behavior, it was promisingly possible to adjust the characteristics of the hydrogels for an optimal drug release. The outcome of this simple and effective approach can potentially offer additional tunable characteristics for recording and stimulating purposes in neural interfaces.

PEG/Dextran Double Layer Influences Fe Ion Release and Colloidal Stability of Iron Oxide Nanoparticles

Despite preliminary confidence on biosafety of polymer coated iron oxide nanoparticles (SPIONs), toxicity concerns have hampered their clinical translation. SPIONs toxicity is known to be due to catalytic activity of their surface and release of toxic Fe ions originating from the core biodegradation, leading to the generation of reactive oxygen species (ROS). Here, we hypothesized that a double-layer polymeric corona comprising of dextran as an interior, and polyethylene glycol (PEG) as an exterior layer better shields the core SPIONs. We found that ROS generation was cell specific and depended on SPIONs concentration, although it was reduced by sufficient PEG immobilization or 100 µM deferoxamine. 24 h following injection, PEGylated samples showed reduction of biodistribution in liver, heterogenous biodistribution profile in spleen, and no influence on NPs blood retention. Sufficient surface masking or administration of deferoxamine could be beneficial strategies in designing and clinical translation of future biomedical SPIONs.

A theranostic nanocomposite system based on radial mesoporous silica hybridized with Fe3O4 nanoparticles for targeted magnetic field responsive chemotherapy of breast cancer

Herein, we report a smart theranostic drug delivery system based on radial mesoporous silica, containing uIO for T₂-weighted MRI and lIO for AMF-responsive chemotherapy.

Antioxidant nanomaterials in advanced diagnoses and treatments of ischemia reperfusion injuries

Organ ischemia with inadequate oxygen supply followed by reperfusion (which initiates a complex of inflammatory responses and oxidative stress) occurs in different clinical conditions and surgical procedures including stroke, myocardial infarction, limb ischemia, renal failure, organ transplantation, free-tissue-transfer, cardiopulmonary bypass, and vascular surgery. Even though pharmacological treatments protect against experimental ischemia reperfusion (I/R) injury, there has not been enough success in their application for patient benefits. The main hurdles in the treatment of I/R injury are the lack of diagnosis tools for understanding the complicated chains of I/R-induced signaling events, especially in the acute phase after ischemia, determining the affected regions of the tissue over time, and then, targeting and safe delivery of antioxidants, drugs, peptides, genes and cells to the areas requiring treatment. Besides the innate antioxidant and free radical scavenging properties, some nanoparticles also show higher flexibility in drug delivery and imaging. This review highlights three main approaches in nanoparticle-mediated targeting of I/R injury: nanoparticles (1) as antioxidants for reducing tissue oxidative stress, (2) for targeted delivery of therapeutic agents to the ischemic regions or cells, and (3) for imaging I/R injury at the molecular, cellular or tissue level and monitoring its evolution using contrasts induced by nanoparticles. These approaches can also be combined to realize so called theranostics for providing simultaneous diagnosis of ischemic regions and treatments by targeted delivery.

Fabrication of egg shell-like nanovesicles from a thiocoumarin-based ε-amino ester: a potential carrier

A thiocoumarin-based ε-amino ester has been designed and synthesized and used to fabricate egg shell-like nanovesicles for sustained release of sulfamethoxazole antibiotic.