Supramolecular Polymerization-Induced Nanoassemblies for Self-Augmented Cascade Chemotherapy and Chemodynamic Therapy of Tumor.

The clinical application of chemodynamic therapy is impeded by the insufficient intracellular H2 O2 level in tumor tissues. Herein, we developed a supramolecular nanoparticle via a simple one-step supramolecular polymerization-induced self-assembly process using platinum (IV) complex-modified ß-cyclodextrin-ferrocene conjugates as supramolecular monomers. The supramolecular nanoparticles could dissociate rapidly upon exposure to endogenous H2 O2 in the tumor and release hydroxyl radicals as well as platinum (IV) prodrugs in situ, which is reduced into cisplatin to significantly promote the generation of H2 O2 in the tumor tissue. Thus, the supramolecular nanomedicine overcomes the limitation of conventional chemodynamic therapy via the self-augmented cascade radical generation and drug release. In addition, dissociated supramolecular nanoparticles could be readily excreted from the body via renal clearance to effectively avoid systemic toxicity and ensure long term biocompatibility of the nanomedicine. This work may provide new insights on the design and development of novel supramolecular nanoassemblies for cascade chemo/chemodynamic therapy.

Type of cell death induced by various metal cations in cultured human gingival fibroblasts.

Metal ions are released from casting alloys and cause damage to cell structures and local inflammation. However, the cytotoxic mechanism and the type of cell death induced in human gingival fibroblast (HGF) by contact with dental metals have not been well characterized. Here the cytotoxicity of eight metals against HGF was investigated. Cytoxicity of metals against HGF was in the following order: Ag(NH(3))(2)F (most cytotoxic)>AgCl>CuCl(2)>CuCl, CoCl(2)> NiCl(2)>FeCl(2), FeCl(3) (least cytotoxic). None of the metals showed any apparent hormetic growth stimulation at lower concentrations, except for Ag(NH(3))(2)F at 20 or higher population-doubling level of HGF. The sensitivity of HGF against Ag(NH(3))(2)F was reduced during in vitro aging, similar to previous report with sodium fluoride. Contact with Ag(NH(3))(2)F for only one hour induced irreversible cell death, whereas longer duration of contact with AgCl or CuCl(2) was necessary to induce irreversible cell death. These metals induced neither DNA fragmentation nor caspase-3 activation. Pan-caspase inhibitor (Z-VAD-FMK) and autophagy inhibitors (3-methyladenine, bafilomycin) did not apparently affect the cytotoxicity of metals, when corrected for the effect of inhibitor alone on growth. We also found that Ag(NH(3))(2)F induced much higher cytotoxicity than AgCl in mouse osteoblastic cell line MC3T3-E1, possibly inducing necrosis. These data suggest the importance of cautious application of Ag(NH(3))(2)F to the oral cavity.

Ferrous sulfate-directed dual-cross-linked hyaluronic acid hydrogels with long-term delivery of donepezil.

Ferrous sulfate (FeSO4)-directed dual-cross-linked hydrogels were designed for application in single-syringe injections. The use of FeSO4, rather than other iron salts, can modulate the gelation time and make it available for subcutaneous injection with a single syringe. These hydrogels are based on hyaluronic acid-dopamine (HA-dp) that contain donepezil (DPZ)-entrapping poly(lactic-co-glycolic acid) (PLGA) microsphere (MS). Although DPZ has been administered orally, its sustained release formulation via subcutaneous injection may reduce the dosing frequency for patients with Alzheimer's disease. The HA-dp conjugate was synthesized via an amide bond reaction for coordination of dp with a metal ion (Fe2+ or Fe3+) and self-polymerization of dp. The HA-dp/DPZ-loaded PLGA MS (PD MS)/FeSO4 gel system was considerably hardened via both the coordination of the metal ion with HA-dp and covalent bonding of dp. In addition, a quick restoration of the collapsed gel structure and sustained DPZ release from the HA-dp/PD MS/FeSO4 structure were achieved. The pharmacokinetic parameters after its subcutaneous injection in a rat indicate the sustained release and absorption of DPZ from the HA-dp/PD MS/FeSO4 system. The proposed system can be prepared by a simple method and can be efficiently and safely used for the long-term delivery of DPZ after the subcutaneous injection.

Toxicity assessment of wearable wound sensor constituents on keratinocytes.

This research reports on the cytotoxicity of materials present in a wound biosensor on human keratinocytes (HaCaT) to evaluate the biocompatibility of the sensor for continuous wound monitoring applications. Individual and collective effects of the sensor materials, gold (Au) and silver (Ag) nanoparticles (NPs), uricase enzyme (UOx), ferrocene carboxylic acid (FCA), multi-walled carbon nanotubes (MWCNTs) and poly vinyl alcohol-based polymer (PVA-SbQ) on HaCaT were studied. The toxicology profiles of these materials were derived from cell viability, mitochondrial activity retention and apoptotic behavior studies. At the concentrations present in the sensor, the cell viability studies showed minimal toxicity for Au and Ag NPs, UOx and FCA (cell viability >75%), while MWCNTs and PVA-SbQ exhibited excellent biocompatibility towards keratinocytes (cell viability >90%). Resazurin assay confirmed minimal impairment of mitochondrial activity at lower concentrations for all the materials (mitochondrial activity >0.7). The caspase-3/7 apoptotic assay showed no pronounced apoptotic behavior caused by the materials. The material mixtures studied were Au/UOx/FCA/PVA-SbQ, Ag/UOx/FCA/PVA-SbQ, and MWCNTs/UOx/FCA/PVA-SbQ. A higher toxicity profile was observed for the heterogeneous material mixtures as a result of the cumulative effect of the individual materials. However, the biosensor itself was seen to exhibit lower toxicity (~5%) compared to the material mixtures, due to the protective PVA-SbQ capping over the biosensor. This work establishes the biocompatibility of the reported wound sensor for human measurements with minimal toxic effects on human keratinocytes.

Polyacrylic acid coated and non-coated iron oxide nanoparticles are not genotoxic to human T lymphocytes.

The use of iron oxide nanoparticles (ION) for diagnostic and therapeutic purposes requires a clear favorable risk-benefit ratio. This work was performed with the aim of studying the ability of polyacrylic acid (PAA)-coated and non-coated ION to induce genotoxicity in human T lymphocytes. For that purpose, their influence on cell cycle progression and on the induction of chromosome aberrations was evaluated. Blood samples collected from healthy human donors were exposed to PAA-coated and non-coated ION, at different concentrations, for 48h. The obtained results showed that, for all culture conditions, the tested ION are not genotoxic and do not influence the cell cycle arrest. Their possible cumulative effect with the iron-dependent genotoxic agent BLM was also evaluated. Blood samples collected from healthy human donors were exposed to ION, at different concentrations, for 48h, in the presence of a pre-determined toxic concentration of BLM. The obtained results showed that, for all culture conditions, the tested ION do not potentiate the clastogenic effects of BLM.

[Inhibitory effects of tea polyphenols and vitamin C on lipid peroxidation induced by FeSO4- cysteine in isolated human plasma and carbon tetrachloride-induced liver free radical injury in mice].

OBJECTIVE: To investigate the inhibitory effects of tea polyphenols (TP) and Vitamin C (Vit C) on FeSO4-cysteine induced lipid peroxidation in isolated human plasma and carbon tetrachloride (CCl4) induced liver free radical injury in mice. METHOD: The experiment included two parts: (1) In FeSO4-cysteine induced lipid peroxidation system of isolated human plasma, malondialdehyde (MDA) content was detected after administration of different concentrations of TP (0.3 ~ 8.1 mg/L, as C ~ F group) and Vit C (3 ~ 81 mg/L, as G ~ J group) respectively; (2) Thirty-six male Kunming mice were randomly divided into four groups: control group (A), CCl4 damage group (B), TP protection group (C) and Vit C protection group (D). TP or Vit C (100 mg/kg) was given orally to group C and D respectively, while the same volume of distilled water was given to the other two groups one time every day, continued for three days. Twelve hours after the final treatment, CCl4 (230 mg/kg) was given orally to group B ~ D. Thirty six hours later, all the mice were decapitated and liver homogenate were prepared for measuring MDA content. RESULT: In FeSO4-cysteine induced lipid peroxidation in isolated human plasma, the inhibitory rate of TP (0.3 ~ 8.1 mg/L) was 30.7%, 32.0%, 46.9% and 59.7 %, and the inhibitory rate of Vit C (3 ~ 8.1 mg/L) was 8.3%, 41.4%, 47.7% and 52.7% for various dosages. In the CCl4 induced liver free radical injury system, the inhibitory rate of the same dosage of TP and Vit C was 45.2%, 42.8% respectively. CONCLUSION: TP (0.3 ~ 8.1 mg/L) and Vit C (9 ~ 81 mg/L) had inhibited lipid peroxidation induced by FeSO4-cysteine in isolated human plasma significantly, and the inhibitory effects of TP was superior to that of Vit C at the same dosages. The same dosage of TP and Vit C had remarkable inhibitory effects on the CCl4 induced liver free radical injury, but there was no significant difference between the two groups.

Interaction of polyacrylic acid coated and non-coated iron oxide nanoparticles with human neutrophils.

Iron oxide nanoparticles (ION), with different coatings and sizes, have attracted extensive interest in the last years to be applied in drug delivery, cancer therapy and as contrast agents in imagiologic techniques such as magnetic resonance imaging. However, the safety of these nanoparticles is still not completely established, particularly to host defense systems that are usually recruited for their clearance from the body. In this paper, given the importance of neutrophils in the immune response of the organism to nanoparticles, the effect of polyacrylic acid (PAA)-coated and non-coated ION on human neutrophils was evaluated in vitro, namely their capacity to activate the oxidative burst and to modify their lifespan. The obtained results showed that the studied PAA-coated and non-coated ION triggered neutrophils' oxidative burst in a NADPH oxidase dependent manner, and that PAA-coated ION increased - while non-coated ION prevented - apoptotic signaling and apoptosis. These effects may have important clinical implications in biomedical applications of ION.

Cell toxicity of superparamagnetic iron oxide nanoparticles.

The performance of nanoparticles for biomedical applications is often assessed by their narrow size distribution, suitable magnetic saturation and low toxicity effects. In this work, superparamagnetic iron oxide nanoparticles (SPIONs) with different size, shape and saturation magnetization levels were synthesized via a co-precipitation technique using ferrous salts with a Fe(3+)/Fe(2+) mole ratio equal to 2. A parametric study is conducted, based on a uniform design-of-experiments methodology and a critical polymer/iron mass ratio (r-ratio) for obtaining SPION with narrow size distribution, suitable magnetic saturation, and optimum biocompatibility is identified. Polyvinyl alcohol (PVA) has been used as the nanoparticle coating material, owing to its low toxicity. A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay is used to investigate the cell biocompatibility/toxicity effects of the samples. From the MTT assay results, it is observed that the biocompatibility of the nanoparticles, based on cell viabilities, can be enhanced by increasing the r-ratio, regardless of the stirring rate. This effect is mainly due to the growth of the particle hydrodynamic size, causing lower cell toxicity effects.

Antioxidant action of the antiarrhythmic drug mexiletine in brain membranes.

Mexiletine is a class Ib antiarrhythmic drug used in the treatment of ventricular arrhythmias. The Na+ channel blocker mexiletine inhibits calcium influx in cells via decreasing reverse operation of the Na+-Ca2+ exchanger. Thus this drug is shown to protect the CNS white matter against anoxic/ischemic injury. The aim of our study was to investigate if this drug could act as an antioxidant drug as well. The antioxidant action of this drug was studied under different oxidant conditions in vitro, and thiobarbituric acid-reactive substances were measured to follow lipid peroxidation. Mexiletine inhibited iron-ascorbate-H2O2-induced lipid peroxidation in brain membranes, liver microsomes and phospholipid liposomes, being most effective in brain membranes. The inhibition was dose- and time-dependent. Mexiletine also inhibited copper-ascorbate-H2O2-induced lipid peroxidation but to a lesser extent. It is concluded that mexiletine has a dual effect toward oxidative injury in brain, both by inhibiting Na+-Ca2+ exchanger-dependent Ca2+ influx and by acting as an inhibitor of lipid peroxidation. However, as this drug is effective at millimolar concentrations, it should be considered less active than natural antioxidants that are effective at micromolar concentrations.