Extracorporeal magnetic approach to reduce the unwanted side-effects and improve antibacterial activity of Ag/Fe3 O4 nanocomposites in rat.

While Ag nanoparticles hold great promise for broad spectrum antibacterial activity, the potential risks of Ag nanoparticles (NPs) on human health remain a challenge. In this study, Ag/Fe3 O4 composites have been successfully prepared and characterized by transmission electron microscopy, X-ray powder diffraction, and Fourier-transform infrared spectroscopy, and their magnetic and antibacterial properties have been assessed. In vivo results show that the antibacterial effect of 500 µg/mL Ag/Fe3 O4 nanocomposites was significantly higher than that of 1000 µg/mL AgNPs after 72 h of treatment (p < 0.01). Hematoxylin and eosin (HE) staining showed that squamous epithelium and dermis collagen fibers formed in the Ag/Fe3 O4 group after 8 days treatment. Wound closure was significantly better for the Ag/Fe3 O4 group than for the AgNPs group. On the other hand, there was less Ag in blood, liver, and kidney in the Ag/Fe3 O4 group, as more Ag was retained in the wound. According to lactate dehydrogenase, γ-glutamyl transpeptidase, and reactive oxygen species results, Ag/Fe3 O4 nanocomposites caused less unwanted side-effects. This work presents a new paradigm to reduce the unwanted side-effects of AgNPs and improve their antibacterial activity, providing a new avenue for wound healing. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2029-2036, 2018.

Evaluation of a two-stage antibacterial hydrogel dressing for healing in an infected diabetic wound.

Various types of wound dressings have been used to treat complex infections in diabetes mellitus. This study is the first to evaluate the healing effects using a two-stage dressing in infected diabetic wounds. A two-stage antibacterial hydrogel dressing (two-stage dressing) was established with two time phases, an antibacterial phase and a drug release phase. We established each phase by using a swelling and rate of drug release test. These results suggested that the antimicrobial phase is activated as soon as the two-stage dressing attaches to the skin. The drugs in the drug release layer of the dressing were released to a greater extent than expected 20-36 h after attachment to the skin, likely due to extensive water absorption. Histological analysis and measurement of vascular endothelial growth factor expression through in vivo testing suggested that the benefits of a two-stage dressing include rapid antibacterial properties, sustained drug release, and promotion of wound healing through cell proliferation as compared with the traditional composite antibacterial hydrogel dressing. Further in vivo tests confirmed that separation of the antibacterial and drug-releasing properties, along with biocompatibility and rapid wound closure rates made two-stage dressings suitable for healing of infected wounds. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1808-1817, 2017.

Fabrication of Waterproof, Breathable Composite Liquid Dressing and Its Application in Diabetic Skin Ulcer Repair.

OBJECTIVES: Diabetic patients are at increased risk of severe skin infections. Covering the wound as early as possible can prevent infection and shorten the course of treatment. In this study, the authors fabricated a waterproof and breathable composite liquid dressing (CLD) that formed a barrier to bacteria and shortened healing time of diabetic rat skin ulcers. METHODS: The CLD was prepared in a formulation that, on evaporation of the liquid carrier, acts as a waterproof, breathable coating on injured skin. The coating was analyzed for water resistance, moisture vapor transmission rate (MVTR), bacterial barrier properties, sustained-release function, and biosafety. A chemically induced rat model of diabetic foot ulcers was used to examine the wound healing effect of CLD and CLD that contained Dermlin (Yensen Biotech Co, Jiangyin, Jiangsu, China). The wound healing rate, histologic changes, and epidermal growth factor expression were also evaluated. RESULTS: The CLD functioned as an effective barrier against infection, was waterproof, had a suitable MVTR, and had effective biosafety. The synergistic effects of CLD and Dermlin had a rapid wound closure rate. Histologic analysis and measurement of epidermal growth factor expression through an in vivo test revealed that the possible mechanism of the CLD effects included the reduction of inflammation and promotion of cell proliferation. CONCLUSIONS: Early treatment with the CLD can prevent infection. In combination with Dermlin, the CLD may promote better wound closure in diabetic skin ulcers. The authors' study suggests a novel strategy for ulcer healing.

Effect of "phase change" complex on postoperative adhesion prevention.

BACKGROUND: Postsurgical peritoneal adhesion is a major clinical problem. Numerous anti-adhesion products have been studied, but none could be easily used to provide a physical barrier. In this study, we developed a "phase change" anti-adhesion barrier for reducing peritoneal adhesion by cross-linked copolymerization of O-carboxymethyl chitosan (CMC) and CaCl2 and addition of cyclosporin A (CsA). MATERIALS AND METHODS: The CMC-CaCl2-CsA compound was characterized by equilibrium swelling rate, weight loss, releasing effect, and coagulation test, and its biosafety was characterized by acute oral toxicity, hemolysis, and cytotoxicity. Intestinal adhesion model was applied on 64 Sprague-Dawley rats, which received CMC, CMC-CaCl2, or CMC-CaCl2-CsA treatment. At postoperative days 7 and 14, the rats were euthanized, and adhesions were graded by an investigator blinded to the treatment groups, using a predetermined adhesion scoring system. The cecum and adhesion tissue were stained with hematoxylin and eosin and antibodies for matrix metalloproteinase-9 and TIMP-1 for further histopathologic examination. RESULTS: The phase change anti-adhesive material exhibited effective blood clotting and were nontoxic in clotting experiments and acute toxicity test. The degradation rate could be adjusted using phosphate-buffered solution with varying pH. Adhesions were significantly reduced in the CMC-CaCl2-CsA treatment group compared with the control group (P < 0.001). Expression of matrix metalloproteinase-9 was stronger in CMC-CaCl2-CsA treatment group at 7 days after surgery. CONCLUSIONS: "Phase-change" adhesive can undergo changes after application, and it inhibits the formation of abdominal adhesions after surgery. The material is convenient for using by surgeons and provides an effective tool for intestinal adhesion prevention.

Comparative Study of Biosafety, DNA, and Chromosome Damage of Different-Materials-Modified Fe3O4 in Rats.

The increasing use of modified Fe3O4 magnetic microparticles has raised safety concerns regarding their use and effect on human health. This study assessed the in vivo biosafety, DNA, and chromosome damage of modified Fe3O4 microparticles such as Au@Fe3O4, Ag@Fe3O4, Cs@Fe3O4, Pt@Fe3O4, and CdS@Fe3O4, using spleen-deficient rats. Spleen-deficient rats treated with naked and modified (Au, Cs, Pt) Fe3O4 microparticles (5000 mg/kg) displayed low toxicity. Only treatment with Cds@Fe3O4 resulted in elevated toxicity and death in rats. Au-, Ag-, and Pt-modified Fe3O4 increased the rate of hemolysis in rats relative to treatment with naked Fe3O4. Despite this, Au- and Pt-modified Fe3O4 increased the biocompatibility and reduced DNA and chromosome damage in rats relative to naked Fe3O4. While Cs@Fe3O4 microparticles displayed a higher biocompatibility than naked Fe3O4, they displayed no significant reduction in DNA and chromosome damage. In summary, Au and Pt surface-modified Fe3O4 microparticles display elevated in vivo biosafety compared to unmodified particles. The precious metal material, with good biological compatibility, surface modification of Fe3O4 is an effective strategy to improve the overall safety and potential therapeutic utility of these magnetic materials.

Paper-based analytical devices for electrochemical study of the breathing process of red blood cells.

Herein we utilized the filter paper to physically trap red blood cells (RBC) to observe the breathing process of red blood cells based on the permeability of the filter paper. By integrating double-sided conductive carbon tape as the working electrodes, the device could be applied to monitor electrochemical responses of RBC for up to hundreds of minutes. The differential pulse voltammetry (DPV) peak currents increased under oxygen while decreased under nitrogen, indicating that RBC could take in and release oxygen. Further studies demonstrated that the RBC suspension could more effectively take in oxygen than the solution of hemoglobin and the supernatant of RBC, suggesting the natural advantage of RBC on oxygen transportation. This study implied that simple paper-based analytical devices might be effectively applied in the study of gas-participating reactions and biochemical detections.

Influence of reducing agents on biosafety and biocompatibility of gold nanoparticles.

Extensive biomedical applications of nanoparticles are mainly determined by their safety and compatibility in biological systems. The aim of this study was to compare the biosafety and biocompatibility of gold nanoparticles (GNPs) prepared with HEPES buffer, which is popular for cell culture, and sodium citrate, a frequent reducing agent. From experimental results on the body weight and organ coefficients of acute oral toxicity tests, it could be observed that HEPES-prepared GNPs are biologically safer than citric-prepared GNPs at the same dose of 500 µg/kg. The in vitro cell viability was higher for HEPES-prepared GNPs than citric-prepared GNPs at 5.0- and 10.0-ug/mL concentrations. More reactive oxygen species (ROS) were generated in the cell suspension when supplemented with citric-prepared GNPs than HEPES-prepared GNPs when their concentrations were higher than 20 µg/mL. The results stated that HEPES-prepared GNPs had better biosafety and biocompatibility than citric-prepared GNPs. This study not only revealed the influence of reducing agent on biosafety and biocompatibility of nanomaterials but also provided accumulative evidence for nanomaterials in biomedical applications.

Paper-based electroanalytical devices for in situ determination of salicylic acid in living tomato leaves.

Detection of phytohormones in situ has gained significant attention due to their critical roles in regulating developmental processes and signaling for defenses in plants at low concentration. As one type of plant hormones, salicylic acid has recently been found to be one of pivotal signal molecules for physiological behaviors of plants. Here we report the application of paper-based electroanalytical devices for sensitively in situ detection of salicylic acid in tomato leaves with the sample volume of several microliters. Specifically, disposable working electrodes were fabricated by coating carbon tape with the mixture of multiwall carbon nanotubes and nafion. We observed that the treatment of the modified carbon tape electrodes with oxygen plasma could significantly improve electrochemical responses of salicylic acid. The tomato leaves had a punched hole of 1.5mm diameter to release salicylic acid with minor influence on continuous growth of tomatoes. By incorporating the tomato leaf with the paper-based analytical device, we were able to perform in situ determination of salicylic acid based on its electrocatalytic oxidation. Our experimental results demonstrated that the amounts of salicylic acid differed statistically in normal, phytoene desaturase (PDS) gene silent and diseased (infected by Botrytis cinerea) tomato leaves. By quantifying salicylic acid at the level of several nanograms in situ, the simple paper-based electroanalytical devices could potentially facilitate the study of defense mechanism of plants under biotic and abiotic stresses. This study might also provide a sensitive method with spatiotemporal resolution for mapping of chemicals released from living organisms.

Using nanostructured conductive carbon tape modified with bismuth as the disposable working electrode for stripping analysis in paper-based analytical devices.

Low cost disposable working electrodes are specifically desired for practical applications of electrochemical detection considering maturity of electrochemical stations and data collection protocols. In this paper double-sided conductive adhesive carbon tape with nanostructure was applied to fabricate disposable working electrodes. Being supported by indium tin oxide glass, the prepared carbon tape electrodes were coated with bismuth film for stripping analysis of heavy metal ions. By integrating the bismuth modified electrodes with paper-based analytical devices, we were able to differentiate Zn, Cd and Pb ions with the sample volume of around 15 µL. After the optimization of parameters, including modification of bismuth film and the area of the electrodes, etc., Pb ions could be measured in the linear range from 10 to 500 µg/L with the detection limit of 2 µg/L. Our experimental results revealed that the disposable modified electrodes could be used to quantify migrated lead from toys with the results agreed well with that using atomic absorption spectrometry. Although bismuth modification and stripping analysis could be influenced by the low conductivity of the carbon tape, the low cost disposable carbon tape electrodes take the advantages of large-scaled produced double-sided carbon tape, including its reproducible nanostructure and scaled-up fabrication process. In addition, the preparation of disposable electrodes avoids time-consuming pretreatment and experienced operation. This study implied that the carbon tape might be an alternative candidate for practical applications of electrochemical detection.

Quantum dot (QD)-modified carbon tape electrodes for reproducible electrochemiluminescence (ECL) emission on a paper-based platform.

Stable and sensitive electrochemiluminescence (ECL) detection relies on successful immobilization of quantum dots (QDs) on working electrodes. Herein, we report a new technique to apply double-sided carbon adhesive tape as the working electrode to improve the stability and reproducibility of QD-based ECL emission. CdS QD-modified electrodes were prepared by dropping and drying CdS QD suspension on the carbon adhesive tape supported by indium tin oxide (ITO) glass. The ECL detection was performed with the prepared electrode on a paper-based platform. We tested our system using H(2)O(2) of various concentrations and demonstrated that consistent ECL emission could be obtained. We attribute stable and reproducible ECL emission to the robust attachment of CdS QDs on the carbon adhesive tape. The proposed method could be used to quantify the concentration of dopamine from 1 µM to 10 mM based on the quenching effect of dopamine on ECL emission of CdS QD system using H(2)O(2) as the coreactant. Our approach addressed the problem in the integration of stable QD-based ECL detection with portable paper-based analytical devices. The similar design offers great potential for low-cost electrochemical and ECL analytical instruments.

Immobilization of hemoglobin on the gold colloid modified pretreated glassy carbon electrode for preparing a novel hydrogen peroxide biosensor.

A novel hydrogen peroxide (H2O2) biosensor was developed by immobilizing hemoglobin on the gold colloid modified electrochemical pretreated glassy carbon electrode (PGCE) via the bridging of an ethylenediamine monolayer. This biosensor was characterized by UV-vis reflection spectroscopy (UV-vis), electrochemical impendence spectroscopy (EIS) and cyclic voltammetry (CV). The immobilized Hb exhibited excellent electrocatalytic activity for hydrogen peroxide. The Michaelis-Menten constant (K(m)) was 3.6 mM. The currents were proportional to the H2O2 concentration from 2.6 x 10(-7) to 7.0 x 10(-3) M, and the detection limit was as low as 1.0 x 10(-7) M (S/N = 3).

Construction, application and biosafety of silver nanocrystalline chitosan wound dressing.

A novel wound dressing composed of nano-silver and chitosan was fabricated using a nanometer and self-assembly technology. Sterility and pyrogen testing assessed biosafety, and efficacy was evaluated using Sprague-Dawley rats with deep partial-thickness wounds. Silver sulfadiazine and chitosan film dressings were used as controls. At intervals wound areas were measured, wound tissues biopsied and blood samples taken. Compared with the controls, the silver nanocrystalline chitosan dressing significantly (p<0.01) increased the rate of wound healing and was associated with silver levels in blood and tissues lower than levels associated with the silver sulfadiazine dressing (p<0.01). Sterility and pyrogen tests of the silver nanocrystalline chitosan dressing were negative. Thus this dressing should have wide application in clinical settings.

The immobilization of hepatocytes on 24 nm-sized gold colloid for enhanced hepatocytes proliferation.

Bioartificial liver and hepatocyte transplantation is anticipated to supply a temporary metabolic support for candidates of liver transplantation or for patients with fulminant liver failure. An essential restriction of this form is the inability to acquire an enough amount of hepatocytes. Enhancement of the proliferation and differentiated function of hepatocytes is becoming a pursued target. Here, porcine hepatocytes were successfully immobilized on nano-sized gold colloid particles to construct a "hepatocyte/gold colloid" interface at which hepatocytes can be quickly proliferated. The properties of this resulting interface were characterized and confirmed by scanning electron microscopy and atomic force microscopy. The proliferative mechanism of hepatocytes was also discussed. The proliferated hepatocytes could be applied to the clinic based on their excellent functions for the synthesis of protein, glucose and urea as well as lower lactate dehydrogenase release.

Trace determination of shiomarin using a hanging copper/amalgam drop electrode.

The electrochemical behavior of shiomarin (moxalactam; latamoxef sodium) was investigated at hanging copper/amalgam drop electrode (HCADE) in HCl-KCl solution (pH 1.1). It was found that shiomarin can form complex with Cu(II) and can be adsorbed at the electrode surface. The coordination number is 1 and the number of transfer electron involved in the reaction is 2. The peak current of the complex related to the concentration of shiomarin and was used to determine trace amounts of shiomarin in solution. The linear range of determination is from 1.0 x 10(-9) to 8.0 x 10(-5) M using differential pulse adsorptive cathodic stripping voltammetry (DPAdCSV). The detection limit is about 4.0 x 10(-10) M (t(a)=70 s, S/N=3). The method was also applied to the determination of shiomarin in injection powder and urine sample with satisfactory results.