Improved triclosan delivery by a novel silica-based nanocomposite

In this study, we report on the design, synthesis, and full characterization of a covalently-linked, triclosan silica-based nanoparticles (T-SNPs), coated with a polyaminated shell (NH2 -T-SNPs). Various techniques are used to elucidate and rationalize the potential biological mechanism of action of these novel nanoparticles. NH2 -T-SNPs are found to be potently bactericidal with no detectable lag time for the antimicrobial activity against E. coli and S. aureus. In this context, we also prove that triclosan is the chemical agent that mediated the bactericidal activity of these chemically-modified NPs. The obtained experimental data allows us to pinpoint the actual minimal bactericidal concentrations (MBCs) of triclosan-bound NPs by quantifying intracellular triclosan concentrations. Furthermore, we conduct preliminary cytotoxicity studies, which show that triclosan bound NPs are less cytotoxic (2000 fold) in vitro compared to free-triclosan when tested with various human and mammalian cell lines. Taken together, our results further support the characterization and development of these new nanoscale materials for various biomedical applications.

Pd nanosheet-covered hollow mesoporous silica nanoparticles as a platform for the chemo-photothermal treatment of cancer cells

A versatile system combining chemotherapy with photothermal therapy for cancer cells using Pd nanosheet-covered hollow mesoporous silica nanoparticles is reported. While the hollow mesoporous silica core can be used to load anticancer drugs (i.e., doxorubicin) for chemotherapy, the Pd nanosheets on the surface of particles can convert NIR light into heat for photothermal therapy. More importantly, the loading of Pd nanosheets on hollow mesoporous silica nanospheres can dramatically increase the amount of cellular internalization of the Pd nanosheets: almost 11 times higher than the unloaded Pd nanosheets. The as-prepared nanocomposites efficiently deliver both drugs and heat to cancer cells to improve the therapeutic efficiency with minimal side effects. Compared with chemotherapy or photothermal therapy alone, the combination of chemotherapy and phototherapy can significantly improve the therapeutic efficacy, exhibiting a synergistic effect.

Biomimetic delivery with micro- and nanoparticles

The nascent field of biomimetic delivery with micro- and nanoparticles (MNP) has advanced considerably in recent years. Drawing inspiration from the ways that cells communicate in the body, several different modes of "delivery" (i.e., temporospatial presentation of biological signals) have been investigated in a number of therapeutic contexts. In particular, this review focuses on (1) controlled release formulations that deliver natural soluble factors with physiologically relevant temporal context, (2) presentation of surface-bound ligands to cells, with spatial organization of ligands ranging from isotropic to dynamically anisotropic, and (3) physical properties of particles, including size, shape and mechanical stiffness, which mimic those of natural cells. Importantly, the context provided by multimodal, or multifactor delivery represents a key element of most biomimetic MNP systems, a concept illustrated by an analogy to human interpersonal communication. Regulatory implications of increasingly sophisticated and "cell-like" biomimetic MNP systems are also discussed.

[Protective effect of N-stearoylethanolamine in suspension and in nanocomposite complex in the organs of mice with the Lewis carcinoma under doxorubicin intoxication administration]

The antioxidant effects of N-stearoylethanolamine (NSE) in the nanocomplex composition and in suspension are shown on the model of intoxication by doxorubicin in conditions of development of the Lewis carcinoma in the heart, kidneys and liver tissue and in the blood plasma of female mice. The NSE suspension reduces the level of urea in the blood plasma of mice with the Lewis carcinoma, which growth was revealed as a result of introduction of doxorubicin. Under introduction of nanocomplex the amount of urea remains at the level of that in the intact mice. In the blood plasma of mice with the Lewis carcinoma the NSE suspension and nanocomplex reduce activity of aspartate aminotransferase, the basic marker of necrosis of the heart tissue, growth of which was caused by the tumour development. Doxorubicinum increases activity of alanine aminotransferase, the marker of the liver lesion; introduction of NSE in the nanocomplex composition prevents the growth of the enzyme activity. N-stearoylethanolamine, both in the nanocomplex and in suspension, modulates activity of enzymes of antioxidantive protection of the heart, kidney and liver tissue of mice with the Lewis carcinoma.

Enhancement of cell-based therapeutic angiogenesis using a novel type of injectable scaffolds of hydroxyapatite-polymer nanocomposite microspheres

BACKGROUND

Clinical trials demonstrate the effectiveness of cell-based therapeutic angiogenesis in patients with severe ischemic diseases; however, their success remains limited. Maintaining transplanted cells in place are expected to augment the cell-based therapeutic angiogenesis. We have reported that nano-hydroxyapatite (HAp) coating on medical devices shows marked cell adhesiveness. Using this nanotechnology, HAp-coated poly(l-lactic acid) (PLLA) microspheres, named nano-scaffold (NS), were generated as a non-biological, biodegradable and injectable cell scaffold. We investigate the effectiveness of NS on cell-based therapeutic angiogenesis.

METHODS AND RESULTS

Bone marrow mononuclear cells (BMNC) and NS or control PLLA microspheres (LA) were intramuscularly co-implanted into mice ischemic hindlimbs. When BMNC derived from enhanced green fluorescent protein (EGFP)-transgenic mice were injected into ischemic muscle, the muscle GFP level in NS+BMNC group was approximate fivefold higher than that in BMNC or LA+BMNC groups seven days after operation. Kaplan-Meier analysis demonstrated that NS+BMNC markedly prevented hindlimb necrosis (P<0.05 vs. BMNC or LA+BMNC). NS+BMNC revealed much higher induction of angiogenesis in ischemic tissues and collateral blood flow confirmed by three-dimensional computed tomography angiography than those of BMNC or LA+BMNC groups. NS-enhanced therapeutic angiogenesis and arteriogenesis showed good correlations with increased intramuscular levels of vascular endothelial growth factor and fibroblast growth factor-2. NS co-implantation also prevented apoptotic cell death of transplanted cells, resulting in prolonged cell retention.

CONCLUSION

A novel and feasible injectable cell scaffold potentiates cell-based therapeutic angiogenesis, which could be extremely useful for the treatment of severe ischemic disorders.

Nebulisation of receptor-targeted nanocomplexes for gene delivery to the airway epithelium

Background

Gene therapy mediated by synthetic vectors may provide opportunities for new treatments for cystic fibrosis (CF) via aerosolisation. Vectors for CF must transfect the airway epithelium efficiently and not cause inflammation so they are suitable for repeated dosing. The inhaled aerosol should be deposited in the airways since the cystic fibrosis transmembrane conductance regulator gene (CFTR) is expressed predominantly in the epithelium of the submucosal glands and in the surface airway epithelium. The aim of this project was to develop an optimised aerosol delivery approach applicable to treatment of CF lung disease by gene therapy.

Methodology

The vector suspension investigated in this study comprises receptor-targeting peptides, cationic liposomes and plasmid DNA that self-assemble by electrostatic interactions to form a receptor-targeted nanocomplex (RTN) of approximately 150 nm with a cationic surface charge of +50 mV. The aerodynamic properties of aerosolised nanocomplexes produced with three different nebulisers were compared by determining aerosol deposition in the different stages of a Next Generation Pharmaceutical Impactor (NGI). We also investigated the yield of intact plasmid DNA by agarose gel electrophoresis and densitometry, and transfection efficacies in vitro and in vivo.

Results

RTNs nebulised with the AeroEclipse II BAN were the most effective, compared to other nebulisers tested, for gene delivery both in vitro and in vivo. The biophysical properties of the nanocomplexes were unchanged after nebulisation while the deposition of RTNs suggested a range of aerosol aerodynamic sizes between 5.5 µm–1.4 µm cut off (NGI stages 3–6) compatible with deposition in the central and lower airways.

Conclusions

RTNs showed their ability at delivering genes via nebulisation, thus suggesting their potential applications for therapeutic interventions of cystic fibrosis and other respiratory disorders.

Immunotargeting of collagenase on thrombus

In this study, we aimed to develop a thrombus-targeting delivery system of collagenase bound to a monoclonal antibody, and to investigate the thrombolysis of an immune-conjugate in vitro and in vivo as well as the targeting effect. We prepared the immunizing conjugation of collagenase by the 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDCI) method. In order to conjugate collagenase and a monoclonal antibody, bovine serum albumin was used as a linker, increasing the number of collagenase molecules carried and keeping collagenase and the monoclonal antibody active. In vitro thrombolysis experiments showed that collagenase had a strong dissolving effect on collagen-embolus within 24 hours. We established a rabbit pulmonary embolism model to investigate the thrombolysis effect of collagenase and collagenase immunizing conjugation in vivo. Our results revealed a significant difference between collagenase and collagenase immunizing conjugation (P < 0.05). We also established a rabbit ear edge vein model to investigate the active target of collagenase immunizing conjugation. We found that collagenase immunizing conjugation had active targets, and had a strong ability to dissolve organized thrombi. In conclusion, the thrombus-targeting delivery system of collagenase we developed has active targeting effects on thrombi.

Self-assembly of SiO2/Gd-DTPA-polyethylenimine nanocomposites as magnetic resonance imaging probes

Controlled self-assembly of organic/inorganic magnetic hybrid materials have important applications in magnetic resonance imaging (MRI). In this study, a widely used polycation polyethylenimine was conjugated with gadopentetic acid (Gd-DTPA) as a gadolinium bearing polyelectrolyte (Gd-DTPA-PEI). Next, multilayers of Gd-DTPA-PEI were coated on silica nanoparticles through layer-by-layer (LbL) self-assembly with polyanions as monitored by dynamic light scattering, zeta-potential, and scanning electron microscopy. The thickness of the multilayer film was estimated from quartz crystal microbalance based on counting frequency change of each adsorbed layer. The magnetic relaxation of SiO2/(Gd-DTPA-PEl/polyanion), core-shell nanocomposite was tested at 1.5 T magnetic field in a clinical MRI scanner, and a 3-fold increase in T1 relaxivity to 15.1 Gd mM(-1)s(-1) was noticed comparing to Gd-DTPA small molecules. Dextran sulfate was coated as the outermost layer on the nanocomposite for better biocompatibility as verified by in vitro cytotoxicity studies. This formulation provides good signal intensity enhancement of mouse liver in vivo with only 1/25 dose of clinical standard at 30 and 60 minutes after intravenous injection. This sensitive imaging probe with unique core-shell structures may find broad applications in cellular and molecular imaging.

A mesoporous silica nanosphere-based drug delivery system using an electrically conducting polymer

In this study, a mesoporous silica nanoparticle (MSN)-based nerve growth factor (NGF) delivery system has been successfully embedded within an electroactive polypyrrol (Ppy). The spherical particles with approximately 100 nm diameter possess a large surface-to-volume ratio for the entrapment of NGF into the pores of MSNs while retaining their bioactivity. Direct incorporation of MSN-NGF within Ppy was achieved during electrochemical polymerization. The loading amount and release profile of NGF from the composite was investigated by sandwich ELISA. The NGF incorporation can be controllable by varying particle concentration or by extending electrodeposition time. The morphology and chemical composition of the Ppy/MSN-NGF composite was evaluated by atomic force microscopy (AFM), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and x-ray photoelectron spectroscopy (XPS). Optical and electron microscopy revealed a characteristic attachment of PC 12 cells and the outgrowth of their neurites when grown on the Ppy/MSN-NGF composite as a result of a sustained and controlled release of NGF. In order to observe the effectiveness of electrical stimulation, neurite extension of cells cultured on unstimulated and stimulated Ppy/MSN-NGF was compared. The NGF release in the presence of electrical stimulation promoted significantly greater neurite extension.

[Dental pulp microvascular reaction in cases of dentine caries treatment by modern nanocomposite materials]

Dental pulp hemodynamics in cases of dentine caries treatment by light cured nanocomposite materials was altered that was characterized by its changing indicators and changing hemodynamic regulation mechanisms depending upon carious cavity depth. Microvascular reaction in dental pulp upon hard dental tissues preparation was accompanied by hyperemia development in microcirculatory bed, its character and degree of expression depended upon carious cavity depth. This reaction was amplified after etching and light polymerization. Hemomicrocirculation normalizing in dental pulp after dentine caries treatment was achieved in 1 week in case of intact parodontal tissues and in 1 month in cases of catarrhal gingivitis and parodontosis.

Intelligent biosynthetic nanobiomaterials for hyperthermic combination chemotherapy and thermal drug targeting of HSP90 inhibitor geldanamycin

An intelligent biosynthetic nanobiomaterial (IBN) platform was explored for drug delivery applications for hyperthermic combination chemotherapy and thermal drug targeting. Geldanamycin (GA), a heat shock protein 90 inhibitor, was conjugated to novel thermosensitive poly(K)(8)-poly(VPGXG)(60) block copolymers [K(8)-ELP(1-60)] with guest residues as valine, alanine and glycine in a 5:2:3 ratio at the 'X' position. The conjugates were completely soluble in PBS and showed a characteristic thermosensitive inverse phase transition. [K(8)-ELP(1-60)]-GA conjugate nanoparticles showed a size ranging from 50 to 200 nm depending upon temperature. Relevant to systemic drug delivery in vivo, these IBNs stably disperse in aqueous solution. Cytotoxicity assays have shown that the IBN from [K(8)-ELP(1-60)]-GA conjugates exhibits effective hyperthermic combination chemotherapy with facile heat modulation.

Anti-inflammatory drug incorporation into polymeric nano-hybrids for local controlled release

In this paper we present the formulation, preparation and characterization of new polymeric composite materials containing a nano-hybrid to be used for the controlled molecular delivery of an anti-inflammatory molecule, Diclofenac. The nano-hybrid consists of a layer of double hydroxide of an Mg-Al hydrotalcite type, in which we replaced the chloride anions present in the host galleries with Diclofenac anions by a simple ion-exchange reaction. Different amounts of the hybrid material were incorporated in polycaprolactone and processed as films of 0.15 mm thickness. The composite materials were analyzed by X-ray diffractometry, thermogravimetry and for their mechanical properties, and showed properties even better than those for the pristine polymer. The release process of the anti-inflammatory molecules was very interesting and promising for tuneable drug delivery. It consists of two stages: a first stage, very rapid as a burst in which a small fraction of the drug is released, and of a second stage that is much slower, extending for longer and longer periods. The parameters influencing the drug release were individuated and discussed.