Encapsulation of drug microparticles with self-assembled Fe3O4/alginate hybrid multilayers for targeted controlled release

Specific nanoantibiotics for selective removal of antibiotic-resistant bacteria: New insights in bacterial imprinting based on interfacial biomimetic mineralization

Antibiotic resistance has been a worsening global concern and selective elimination of antibiotic-resistant bacteria (ARB) while retaining the co-existed beneficial bacteria has been essential in environmental protection, which having attracted considerable interest. In this work, by integrating the whole cell imprinting and epitope imprinting strategy, magnetic bacterial imprinted polymers (BIPs) towards ARB were synthesized with interfacial biomimetic mineralization followed by a screening process. The binding data showed that the BIPs owned highly specific affinity towards the target bacteria. Taking advantage of this specific binding ability of BIPs, a two-step selective antimicrobial approach was developed. Remarkably, the BIP nanoantibiotics (nAbts) could efficiently destroy ARB without harming the beneficial bacteria. In comparison with the non-bacterial imprinted polymers, the biocompatible BIP nAbts showed a 12.5-fold increase in the survival percentage for the beneficial bacteria in wastewater. To the best of our knowledge, this is the first time that bacterial imprinting via interfacial biomimetic mineralization was developed, and also the first report of killing ARB without harming the beneficial bacteria in wastewater. We believe that this strategy provides a new insight into the design of novel affinity materials for the selective elimination of ARB in biological treatment for environmental protection.

Preparation, characterization, and in vitro drug release behavior of thiolated alginate nanoparticles loaded budesonide as a potential drug delivery system toward inflammatory bowel diseases

For site-specific drug delivery in inflammatory bowel disease, reducible sodium alginate nanoparticles cross-linked with disulfide linkage were developed. Nanoparticles were synthesized in deionized water through self-assembly of amphiphilic thiolated sodium alginate Alg-Cys and subsequently produced cross-linking of disulfide bonds. TEM image showed a spherical core-shell configuration with a size of about 430 nm for the nanoparticles. Dynamic light scattering (DLS) showed high stability, narrow size distribution, and pH-dependent swelling transition for the nanoparticles. Cytotoxicity study showed that there was no evident cell inhibition among the nanoparticles. Also, the size of the nanoparticles increased in 10 mM glutathione (GSH) solution due to the cleavage of disulfides within their network structures. Compared to that in GSH-free buffer, there was a remarkable increase in drug release in pH 7.4 buffer with GSH from drug-loaded nanoparticles, indicating that the nanoparticles could be used for colon-specific drug delivery.

Polymer Capsules with Hydrophobic Liquid Cores as Functional Nanocarriers

Recent developments in the fabrication of core-shell polymer nanocapsules, as well as their current and future applications, are reported here. Special attention is paid to the newly introduced surfactant-free fabrication method of aqueous dispersions of nanocapsules with hydrophobic liquid cores stabilized by amphiphilic copolymers. Various approaches to the efficient stabilization of such vehicles, tailoring their cores and shells for the fabrication of multifunctional, navigable nanocarriers and/or nanoreactors useful in various fields, are discussed. The emphasis is placed on biomedical applications of polymer nanocapsules, including the delivery of poorly soluble active compounds and contrast agents, as well as their use as theranostic platforms. Other methods of fabrication of polymer-based nanocapsules are briefly presented and compared in the context of their biomedical applications.

ROS-Responsive Chitosan Coated Magnetic Iron Oxide Nanoparticles as Potential Vehicles for Targeted Drug Delivery in Cancer Therapy

Background and Objective

Cancer cells accumulate high concentrations of reactive oxygen species as a result of their faster and uninhibited metabolic activity. Cancer chemotherapeutic agents release an excess of severe adverse reactions as a result of targeting normal cells. This demands an improvement in targeted drug-delivery systems to selectively discharge anticancer drugs in the vicinity of such highly metabolically and mitotically active cells.

Materials and Methods

Here, magnetic nanoparticles were synthesized by a traditional co-precipitation technique. Fe₃O₄@OA-CS-5-FLU-NPs were synthesized by an easy and rapid in situ loading method. The proposed Fe₃O₄@OA-CS-5-FLU-NPs were productively prepared as well as characterized by various spectroscopic and microscopic studies.

Results

The targeted drug release profile of the Fe₃O₄@OA-CS-5-FLU-NPs was studied in the presence of ROS including H₂O₂ and pH induction. The released product, Fe₃O₄@OA-CS-5-FLU-NP, exhibited desirable levels of cytotoxicity and demonstrated morphological changes and inhibition of colony formation for A549 and HeLa S3 cancer cells. The IC50 values at 24 hours were 12.9 and 23 μg/mL, respectively.

Conclusion

In summary, results from the MTT assay, fluorescence staining as well as colony formation assays, revealed that the Fe₃O₄@OA-CS-5-FLU-NPs were active and safe for anticancer biomedical applications. In summary, the present investigation provides a powerful nanostructured based system for improved cancer theranostics that should be further studied.

Magnetically Navigated Core-Shell Polymer Capsules as Nanoreactors Loadable at the Oil/Water Interface

Polymer core-shell nanocapsules with magnetic nanoparticles embedded in their oil cores were fabricated and applied as nano(photo)reactors. Superparamagnetic iron oxide nanoparticles (SPIONs) coated with oleic acid were first synthesized and characterized structurally, and their magnetic properties were determined. The capsules with chitosan-based shells were then formed in a one-step process by sonication-assisted mixing of (1) an aqueous solution of the hydrophobically derived chitosan and (2) oleic acid containing the dispersed SPIONs. In this way, magnetic capsules with a diameter of approximately 500-600 nm containing encapsulated SPIONs with an average diameter of approximately 20-30 nm were formed as revealed by dynamic light scattering and scanning transmission electron microscopy measurements. The composition and magnetic properties of the formed capsules were also followed using dynamic light scattering, electron microscopies, and magnetic force microscopy. The water-dispersible capsules, thanks to their magnetic properties, were then navigated in a static magnetic field gradient and transferred between the water and oil phases, as evidenced by fluorescence microscopy. In this way, the capsules could be loaded in a controlled way with a hydrophobic reactant, perylene, which was later photooxidized upon transferring the capsules to the aqueous phase. The capsules were shown to serve as robust reloadable nanoreactors/nanocontainers that via magnetic navigation can be transferred between immiscible phases without disruption. These features make them promising reusable systems not only for loading and carrying lipophilic actives, conducting useful reactions in the confined environment of the capsules, but also for magnetically separating and guiding the encapsulated active molecules to the site of action.

Multifunctional gold coated iron oxide core-shell nanoparticles stabilized using thiolated sodium alginate for biomedical applications

In this paper we report synthesis of aqueous based gold coated iron oxide nanoparticles to integrate the localized surface plasma resonance (SPR) properties of gold and magnetic properties of iron oxide in a single system. Iron oxide-gold core shell nanoparticles were stabilized by attachment of thiolated sodium alginate to the surface of nanoparticles. Transmission electron microscope (TEM) micrograph presents an average elementary particle size of 8.1±2.1nm. High resolution TEM (HR-TEM) and X-ray photon spectroscopy further confirms the presence of gold shell around iron oxide core. Gold coating is responsible for reducing saturation magnetization (M_s) value from ~41emu/g to ~24emu/g - in thiolated sodium alginate stabilized gold coated iron oxide core-shell nanoparticles. The drug (curcumin) loading efficiency for the prepared nanocomposites was estimated to be around 7.2wt% (72μgdrug/mg nanoparticles) with encapsulation efficiency of 72.8%. Gold-coated iron oxide core-shell nanoparticles could be of immense importance in the field of targeted drug delivery along with capability to be used as contrast agent for MRI & CT.

Layer-by-Layer Assembly of Multifunctional Flame Retardant Based on Brucite, 3-Aminopropyltriethoxysilane, and Alginate and Its Applications in Ethylene-Vinyl Acetate Resin

An efficient and multifunctional brucite/3-aminopropyltriethoxysilane (APTES)/nickel alginate/APTES (B/A/Nia/A) hybrid flame retardant was fabricated via the layer-by-layer assembly technique with brucite, silane coupling agents, nickel chloride, and sodium alginate. The morphology, chemical composition, and structure of the hybrid flame retardant were characterized. The results confirmed the multilayer structure and indicated that the assembled driving forces were electrostatic interactions, dehydration condensation, hydrogen bonds, and coordination bonds. When used in ethylene-vinyl acetate (EVA) resin, the multifunctional flame retardant had better performance than brucite in improving the flame retardancy, smoke suppression, and mechanical properties. With 130 phr loading, the multifunctional flame retardant achieved a limiting oxygen index value of 32.3% and a UL 94 V-0 rating, whereas the brucite achieved only 31.1% and a V-2 rating, respectively. The peak heat release rate and total heat released decreased by 41.5% and 8.9%, respectively. The multifunctional flame retardant had an excellent performance in reducing the smoke, CO, and CO2 production rates. These improvements could be attributed to the catalyzing carbonization of nickel compounds and the formation of more protective char layers. Moreover, the elongation at break increased by 97.5%, which benefited from the improved compatibility and the sacrificial bonds in the nickel alginate. The mechanism of flame retardant, smoke suppression, and toughening is proposed.

Highly scalable production of uniformly-coated superparamagnetic nanoparticles for triggered drug release from alginate hydrogels

Large-scale production of SiO₂-coated Fe₂O₃nanoparticles facilitates their incorporation in stimuli-responsive superparamagnetic alginate hydrogel structures with efficient hyperthermia performance and enhanced triggered drug release.

Synthesis and Controlled Release Behavior of Biodegradable Polymers with Pendant Ibuprofen Group

The continuous use of nonsteroidal anti-inflammatory drugs such as ibuprofen frequently leads to some serious side-effects including stomach ulcers and bleeding. In this paper, two kinds of new biocompatible polyesters (PIGB, PIGH) and polyester-amide (PIGA) comprising biodegradable components (L-glutamic acid,1,4-butanediol, and1,6-hexanediol and6-amino hexanol) and ibuprofen as pendant group have been prepared by the melting polycondensation. The chemical structures of the monomer and polymers are characterized by FTIR,1H NMR spectrum, GPC, and contact angle measurements. The drug loading of ibuprofen reaches very high level (35–37%) for PIGB, PIGH, and PIGA carriers. The free ibuprofen molecules are releasedin vitrofrom polymer carriers in a controlled manner without a burst release, different from the release pattern observed in the other drug-encapsulated systems. It is also found that the different hydrophilicity among PIGB, PIGH, and PIGA plays a key role in the time-controlled release of ibuprofen. In addition, the viability of HeLa cells after 48 h of incubation reaches more than 100%, indicating no cytotoxicity for PIGB, PIGH, and PIGA carriers.

SPION@polydehydroalanine hybrid particles

We report on the coating of superparamagnetic iron oxide nanoparticles using polyanionic or polyzwitterionic materials based on polydehydroalanine. The resulting core–shell hybrid nanoparticles exhibit shells of different charge and thickness.

Layer-by-layer nanoencapsulation of camptothecin with improved activity

160 nm nanocapsules containing up to 60% of camptothecin in the core and 7-8 polyelectrolyte bilayers in the shell were produced by washless layer-by-layer assembly of heparin and block-copolymer of poly-l-lysine and polyethylene glycol. The outer surface of the nanocapsules was additionally modified with polyethylene glycol of 5 kDa or 20 kDa molecular weight to attain protein resistant properties, colloidal stability in serum and prolonged release of the drug from the capsules. An advantage of the LbL coated capsules is the preservation of camptothecin lactone form with the shell assembly starting at acidic pH and improved chemical stability of encapsulated drug at neutral and basic pH, especially in the presence of albumin that makes such formulation more active than free camptothecin. LbL nanocapsules preserve the camptothecin lactone form at pH 7.4 resulting in triple activity of the drug toward CRL2303 glioblastoma cell.