Marek Wojnicki

Tissue distribution of gold nanoparticles after single intravenous administration in mice

BACKGROUND Nanoparticles (a part of matter which size is less than 100 nm) have numerous potential applications in biomedicine, due to their unique surface, electronic and optical properties. The goal of the present study was to examine the distribution of gold nanoparticles (GNPs) in mice after single intravenous administration. METHODS Spherical GNPs were synthesized by chemical reduction of tetrachloroauric acid with ascorbic acid as a reductant. GNPs were stabilized using polyvinyl alcohol (PVA, m.w. = 67000Da) a substance approved for use in the pharmaceutical industry. The size of colloidal gold particles (diameter equals 25 ± 8 nm) was determined using HR SEM and DLS techniques; ζ potential of GNPs was determined using Malvern Zetasizer Nano ZS and it equals -5.2 ± 5.4 mV. An aqueous dispersion of GNPs was administered to mice in a dose of about 10 cm(3)/kg and 24 h later the amount of gold in different organs was determined using the inductively coupled plasma mass spectrometer (ICP MS). Initial concentration of GNPs equals 29.55 mg/l. RESULTS GNPs after single intravenous administration preferentially accumulated in the liver (12.7% of the applied dose), while the other organs accumulated around 0.1% or less. CONCLUSION Colloidal GNPs of the used size (about 25 ± 8 nm) provide new potential route for direct delivery system to the liver, which may be important e.g., in liver cancer diagnosis.

Catalytic Properties of Platinum Nanoparticles Obtained in a Single Step Simultaneous Reduction of Pt(IV) Ions and Graphene Oxide

A composite material consisting of metallic platinum nanoparticles and reduced graphene oxide was successfully obtained in microflow reactor. Moreover, subnanometric platinum particles were observed. Reduced graphene oxide plays an important role as a stabilizing agent for platinum nanoparticles. Reduced graphene oxide coverage and platinum particle size as well as size distribution depend mainly on initial concentration of platinum(IV) ions. High level of reduced graphene oxide coverage by platinum nanoparticles (PtNPs) was obtained and is equal to 71%. This in turn effects significantly the mass ratio of reduced graphene oxide to PtNPs which is equal to 49% (w/w). Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) analysis of the obtained materials were performed. Also, catalytic properties of the obtained composite material consisting of PtNPs at reduced graphene oxide surface, towards electrochemical glucose oxidation, were investigated. It was found that the studied materials exhibit high catalytic activity for glucose electro-oxidation process.

Kinetic studies of nucleation and growth of palladium nanoparticles

In this paper, the kinetic studies of nucleation and growth processes of palladium nanoparticles formation are presented. As a palladium precursor the chloride complex of Pd(II) and as a reductant l-ascorbic acid, were used. Kinetic studies were conducted under different experimental conditions such as initial concentration of metal ions, ascorbic acid, chloride ions as well as at different temperature and ionic strength. Using Finke-Watzky model kinetic rate constants were established and discussed. The value of activation enthalpy and entropy have also been determined using Eyring-Polanyi equation. For all obtained colloids, plasmons and values of hydrodynamic radius were registered.

Kinetic Studies of Gold Recovery from Diluted Chloride Aqueous Solutions Using Activated Carbon Organosorb 10 CO

The kinetic studies of gold(iii) chloride complex ions recovery from acidic solution using activated carbon (AC) were carried out using spectrophotometry. AC samples were characterized in terms of surface area, porosity, and zeta potential. The surface functional groups were also identified. It was found that adsorption of AuCl4– onto AC was followed by reduction of the ions to the metallic form. The process obeyed the first order reaction model, but the reaction was controlled by diffusion. Arrhenius and Eyring–Polanyi equations were used for determination of the activation parameters. Distribution of gold across the AC pellets was also determined and discussed according to the porous material theory.

Single-step synthesis of onion-like Au—Pd—PtNPs nanoparticles using microflow system

This paper describes the method of onion-like nanoparticles synthesis in a microflow. As the core of a material, platinum nanoparticles were used. The first shell consists of metallic palladium, and the second one is metallic gold, respectively. The synthesis of onion-like nanostructure was performed using microflow reactors system, which consists of 3 independent elements. As the reducing agent of precious metals ions, vitamin C was used. To prevent NPs from the aggregation, a polyvinyl alcohol as the stabilizing agent was applied.

Kinetic studies of gold recovery from dilute aqueous solutions using Fe2+ chloride ions

The kinetics of Au3+ chloride complex ions reduction using Fe2+ chloride ions was investigated by stopped-flow method. The influence of initial concentrations of Au3+ chloride ions, Fe2+ ions, chloride ions, neutral salt (NaClO4), pH of the solution and temperature was investigated. Activation energy was determined to be 42.36 kJ/mol. Moreover, the kinetic equation was postulated. Obtained solid phase was analyzed using SEM techniques. Particles size varies in the range from 0.5 to 5 μm. It was shown that gold can be removed from the solution by the reduction of Au3+ chloride ions and filtration of precipitant.

Novel and effective synthesis protocol of AgNPs functionalized using L-cysteine as a potential drug carrier

In this study, the protocol of a single-step l-cysteine functionalized silver nanoparticle synthesis was described. Particle size distribution was determined. The crystallinity and chemical properties were investigated using XRD, HR-TEM, and XPS methods. Acute toxicity and irritant properties of obtained nanoparticles were studied using mice and rats as an animal model. The results showed that thanks to the applied protocol, it was possible to synthesize silver nanoparticles with narrow particle size distribution. Moreover, the concentration of final product was extremely high in comparison to other known methods. These nanoparticles showed neither irritant properties nor acute toxicity.

Micro Droplet Formation towards Continuous Nanoparticles Synthesis

In this paper, micro droplets are generated in a microfluidic focusing contactor and then they move sequentially in a free-flowing mode (no wall contact). For this purpose, two different micro-flow glass devices (hydrophobic and hydrophilic) were used. During the study, the influence of the flow rate of the water phase and the oil phase on the droplet size and size distribution was investigated. Moreover, the influence of the oil phase viscosity on the droplet size was analyzed. It was found that the size and size distribution of the droplets can be controlled simply by the aqueous phase flow rate. Additionally, 2D simulations to determine the droplet size were performed and compared with the experiment.

Platinum(iv) Chloride Complex Ions Adsorption on Activated Carbon Organosorb 10CO

Kinetic studies on the recovery of platinum(iv) chloride complex ions from acidic solutions using commercially available activated carbon (AC) were carried out using spectrophotometric methods. The overall process obeyed first-order reaction model. The overall process is complex and consists of two steps: the first one is related to the reversible adsorption–desorption of PtIV complex and the second one is related to the reduction of PtIV complex on the AC surface. The first step of the overall process was limited by diffusion, whereas the second step ran under kinetic control. The activation energies of the individual reactions in both steps were determined and corresponded to 18.27, 7.85, and 31.2 kJ mol–1 for the adsorption, desorption, and reduction reactions, respectively. X-ray photoelectron spectroscopy results confirmed that the chemical reaction was related to the reduction of PtIV to PtII on the AC surface. The results show that the investigated AC can be applied for platinum recovery from highly diluted aqueous systems.