Two-step single-reactor synthesis of oleic acid- or undecylenic acid-stabilized magnetic nanoparticles by thermal decomposition

Different iron oxides (i.e., magnetite, maghemite, goethite, wüstite), particularly nanosized particles, show distinct effects on living organisms. Thus, it is of primary importance for their biomedical applications that the morphology and phase-structural state of these materials are investigated. The aim of this work was to obtain magnetic nanoparticles in a single reactor using Fe(III) acetylacetonate as the initial precursor for the synthesis of Fe(III) oleate or Fe(III) undecylate followed by their thermolysis in situ. We proposed a new approach, according to which the essential magnetite precursor (a complex salt of higher acids - Fe(III) alkanoates) is obtained in a solvent with a high boiling point via displacement reaction of acetylacetone with a higher acid from Fe(III) acetylacetonate during its elimination from the reaction mixture under vacuum conditions. Magnetic nanoparticles (NPM) were characterized in terms of morphology, hydrodynamic diameter, and composition via several techniques, such as transmission electron microscopy, dynamic light scattering, thermogravimetric analysis, Fourier-transform infrared spectroscopy/attenuated total reflectance, ⁵⁷Fe Mössbauer spectroscopy, and X-ray diffraction. The effect of unsaturated oleic (OA) and undecylenic (UA) acids, which are both used as a reagent and as a nanoparticle stabilizer, as well as the influence of their ratio to Fe(III) acetylacetonate on the properties of particles were investigated. Stable dispersions of NPM were obtained in 1-octadecene within the OA or UA ratio from 3.3 mol to 1 mol of acetylacetonate and up to 5.5 mol/mol. Below the mentioned limit, NPM dispersions were colloidally unstable, and at higher ratios no NPM were formed which could be precipitated by an applied magnetic field. Monodisperse nanoparticles of iron oxides were synthesized with a diameter of 8-13 nm and 11-16 nm using OA and UA, respectively. The organic shell that enables the particle to be dispersed in organic media, in the case of oleic acid, covers their inorganic core only with a layer similar to the monomolecular layer, whereas the undecylenic acid forms a thicker layer, which is 65% of the particle mass. The result is a significantly different resistance to oxidation of the nanoparticle inorganic cores. The core of the particles synthesized using oleic acid is composed of more than 90% of maghemite. When undecylenic acid is used for the synthesis, the core is composed of 75% of magnetite.

A Facile Strategy to Prepare an Enzyme-Responsive Mussel Mimetic Coating for Drug Delivery Based on Mesoporous Silica Nanoparticles

Surface functional mesoporous silica nanoparticles (MSNs) have been widely used as promosing materials for drug delivery. Herein, we reported a facile strategy to construct MSNs coated by enzyme-resposive polylysine-dopamine (PLDA) films through self-polymerization of dopamine derivative lysine-dopamine, in which the drug could be loaded and delivered efficiently. In detail, RhB or DOX was used as a drug model and loaded in functional MSNs via a one-pot procedure among MSNs, drug, and lysine-dopamine (LDA) under basic conditions. Owing to the fact that the peptide bonds between lysine and dopamine can be cleaved under triggering by pepsin, the resulting RhB/DOX@PLDA-MSNs exibit enzyme-responsive characterization. After the DOX@PLDA-MSNs enter into the cancer cells, the drug can be released effectively through degradation of peptide bonds under the influence of enzyme in cancer cells, which shows marked anticancer activity in vitro. This facile strategy may provide a new platform to construct enzyme-responsive controlled drug delivery systems.

Molecularly imprinted cryogel membranes for mitomycin C delivery

In this study, cryogel-based implantable molecularly imprinted drug delivery systems were designed for the delivery of antineoplastic agent. Mitomycin C imprinted poly(2-hydroxyethyl methacrylate-N-methacryloyl-l-glutamic acid) cryogel membranes were produced by free-radical bulk polymerization under partially frozen conditions. The membranes were characterized by swelling tests, Fourier transform infrared spectroscopy, scanning electron microscopy, surface area measurements and in vitro hemocompatibility tests. In vitro delivery studies were carried out to examine the effects of cross-linker ratio and template content. Mitomycin C imprinted cryogel membranes have megaporous structure (10-100 μm in diameter). The cumulative release of mitomycin C was decreased with increasing cross-linking agent ratio and increased with the amount of template in the cryogel structure. The nature of transport mechanism of the mitomycin C from the membranes was non-Fickian.

Drug-loaded liposome-capped mesoporous core-shell magnetic nanoparticles for cellular toxicity study

Liposome-capped core-shell mesoporous silica-coated superparamagnetic iron oxide nanoparticles called 'magnetic protocells' were prepared as novel nanocomposites and used for loading anticancer drug doxorubicin (DOX) for cellular toxicity study. Cytotoxicity of the magnetic protocells with or without DOX was tested in vitro on commercial MCF7 and U87 cell lines under alternating magnetic field. MCF7 cell line treated with the DOX-loaded nanoparticles under alternating magnetic field exhibited nearly 20% lower survival rate after 24 h compared with cells treated with free DOX and similarly, it was around 24% when applied to U87. The results indicate that the magnetic protocells could be useful for future cancer treatment in vivo by the combination of targeted drug delivery and magnetic hyperthermia.

Tannin as a gatekeeper of pH-responsive mesoporous silica nanoparticles for drug delivery

Tannin grafted on mesoporous silica nanoparticles (tannin-MSNs) was synthesized by the amidation reaction of carboxyl benzyl borate with amino group modified MSN.

Tumor-targeted co-delivery of mitomycin C and 10-hydroxycamptothecin via micellar nanocarriers for enhanced anticancer efficacy

Polymer–lipid hybrid micelles co-delivered hydrophilic mitomycin C and hydrophobic 10-hydroxycamptothecin showed improved cellular uptake and cytotoxicity in vitro and enhanced tumor accumulation and antitumor activity in vivo.

Porous polyurea network showing aggregation induced white light emission, applications as biosensor and scaffold for drug delivery

We have designed a urea functionalized novel nanoporous material, POP-PU, which showsaggregation induced white light emission in the presence of suitable polar solvents. This nanomaterial has been explored as a pseudowhite light emitter where the polymeric luminogen moiety can interact with the suitable polar solvent, leading to charge transfer. Thus, solvent assisted rotational freezing of nonrigid polymeric nanoparticles gives radiative emission and the whole solution emits white light with color temperature of 8533 K. This nanoporous material also holds the pockets (donor-donor-acceptor array) for specific biomolecular interaction. Among three pyrimidine based nucleotide bases, only cytosine can amplify the PL emission intensity of POP-PU and the other two bases cannot, suggesting its future potential as a biosensor. Further, this urea functionalized porous organic nanomaterial can be utilized as an efficient drug-delivery vehicle for liver cancer diagnostics and therapy based on the specific biomolecular interaction at its surface.

Size-controlled porous superparamagnetic Zn1/3Fe8/3O4 nanospheres: synthesis, properties and application for drug delivery

Magnetic nanospheres have recently attracted much attention in the biomedical areas due to their good biocompatibility and unique magnetic features.