Production Of Stable Nanoparticles Research Articles

Copper(i) as a reducing agent for the synthesis of bimetallic PtCu catalytic nanoparticles.

This work investigates the potential utilization of Cu(i) as a reducing agent for the transformation of the platinum salt K2PtCl4, resulting in the production of stable nanoparticles. The synthesized nanoparticles exhibit a bimetallic composition, incorporating copper within their final structure. This approach offers a convenient and accessible methodology for the production of bimetallic nanostructures. The catalytic properties of these novel nanomaterials have been explored in various applications, including their use as artificial metalloenzymes and in the degradation of dyes. The findings underscore the significant potential of Cu(i)-mediated reduction in the development of functional nanomaterials with diverse catalytic applications.

Green Synthesis of Silver Nanoparticles and Study of Their Antimicrobial Properties

One of the major disadvantages of polymers when used in food-contact applications is that they are very susceptible to microbial attack. On the other hand, silver nanoparticles have received increased attention as novel antimicrobial agents. Therefore, the introduction of silver nanoparticles into conventional polymers results in new materials with improved properties. In this investigation, colloidal silver nanoparticles using an environmentally friendly procedure were synthesized. An aqueous solution of AgNO3 was used as a silver precursor with ‘green’ reducing agents either different types of honey, or β-d-glucose. In the first case, different pH values, as well as the addition of poly(ethylene glycol), PEG were studied, while in the latter, the effect of reduction time in the presence of PEG with various average molecular weights was examined. Properties of the nanoparticles were measured using X-Ray diffraction, UV–Vis and FTIR spectroscopy. Using honey it seems that spherical particles are produced with the smaller average particle size obtained at pH 8.5. Use of honey has the advantage of being a natural product, although its main drawback is that its composition varies and it cannot be predefined to result in reproducible results. Use of β-d-glucose results in stable silver nanoparticles with small average particle size after 24 h reduction. The addition of low molecular weight PEG seems to be beneficial in the production of stable nanoparticles. Finally, the antimicrobial activity of the nanoparticles produced was investigated at different concentrations on both Gram positive and negative bacteria, such as Bacillus cereus, Bacillus subtilis, Escherichia coli and Staphylococcus aureus.

Oxidation-Sensitive Polymeric Nanoparticles

We have recently demonstrated the possible use of organic polysulfides for the design of oxidation-sensitive colloidal carriers in the form of polymeric vesicles, which are particularly suitable for the encapsulation of hydrosoluble drugs. In the present research we extend our efforts to carriers specifically suitable for hydrophobic molecules. Exploiting the living emulsion polymerization of episulfides, we have produced new cross-linked polysulfide nanoparticles. Here we demonstrate how this process allows the production of stable nanoparticles with a good control over their size and functionality. The nanoparticles showed negligible cytotoxicity on a fibroblast model; furthermore, they exhibited sensitivity to oxidative conditions, which first produce swelling and then solubilize the material.

Gadolinium-Loaded Nanoparticles Engineered from Microemulsion Templates

ABSTRACTMicroemulsions (oil-in-water) have been used as templates to engineer stable emulsifying wax and Brij 72 (polyoxyl 2 stearyl ether) nanoparticles. The technique is simple, reproducible, and amenable to large-scale production of stable nanoparticles having diameters below 100 nm. Investigation of the process variables showed that the amount of surfactant used in the preparation of microemulsion templates had the greatest influence on the microemulsion window, as well as the properties and stability of the cured nanoparticles. Emulsifying wax and Brij 72 nanoparticles (2 mg/mL) made with 3 mM polyoxyl 20 stearyl ether and 2.3 mM polysorbate 80, respectively, were the most stable based on retention of nanoparticle size over time. Gadolinium acetylacetonate (GdAcAc), a potential anticancer agent for neutron capture therapy (NCT), was entrapped in stable nanoparticles. The apparent water solubility of GdAcAc was increased more than 2000-fold by entrapment into nanoparticles. The entrapment efficiency of GdAcAc was about 100% for emulsifying wax nanoparticles and 86% for Brij 72 nanoparticles, as determined by gel permeation chromatography (GPC). Elution profiles were obtained with light scattering (counts per second) to detect nanoparticles and ultraviolet (UV) absorption of GdAcAc at 288 nm. Challenges of these cured nanoparticles in biologically relevant media such as 10% fetal bovine serum, 10 mM phosphate-buffered saline, 150 mM NaCl, and 10% lactose at 37°C for 60 min demonstrated that these nanoparticles are stable. The ease of preparation of these very small and stable nanoparticles, and the ability to entrap lipophilic drugs such as GdAcAc with high efficiency, suggested that these systems may have potential in cell targeting, especially for specific delivery to tumor cells for NCT.

Nanoparticles and Polymeric Vesicles From New Poly-L-Lysine Based Amphiphiles

AbstractNanoparticles and polymeric vesicles for drug delivery and other industrial applications have been prepared by the probe sonication of poly-L-lysine graft copolymer amphiphiles in aqueous media. The amphiphiles, which have a poly-L-lysine backbone and varied levels of both hydrophilic methoxypolyethylene glycol (Mw ∼ 5,000) and hydrophobic palmitoyl pendant groups, were prepared from 2 different molecular weight poly-L-lysine hydrobromide samples (Mw ∼4,000 and ∼20,000 respectively). Poly-L-lysine based amphiphilic polymers (PLPs) were characterised using light scattering, 1H NMR and an assay for the level of free amino groups. Steric factors appear to limit the final level of lysine group modification that can be achieved and even an excess amount of grafting reactants still resulted in the production of polymers in which 22 – 26 mole% of the lysine terminal amino groups remain unsubstituted. Polymeric unilamellar vesicles (220 – 570nm in diameter) imaged by electron microscopy were produced by probe sonication of PLP, cholesterol. Vesicle formation was possible over a narrow spectrum of polymer architecture and was favoured by a low molecular weight and a low level of palmitoyl substitution. A vesicle formation index (F') has thus been derived for this PLP, cholesterol system = Where H = %molar level of unreacted L-lysine units, L = %molar level of substituted palmitoyl units and DP = square root of the degree of polymerisation of the polymer. Probe sonication of an aqueous dispersion of PLP samples resulted in the production of stable nanoparticles (80 -170nm in diameter) as imaged by electron microscopy. Nanoparticles were able to encapsulate the hydrophilic fluorophore fluorescein isothiocyanate (FITC)-dextran and encapsulation increased as the level of unreacted lysine terminal amino groups in PLP increased thus increasing as the level of hydrophilic domains increased. The size of both the nanoparticles and the vesicles was directly influenced by the molecular weight of PLP. PLPs of molecular weight 32,000 – 48,000 and 89,000 – 140,000 resulted in nanoparticles of 85 – 114 nm and 125 – 167 nm in diameter respectively and PLP of molecular weight 25,000 and 89,000 gave rise to polymeric vesicles of 252 nm and 570 nm in diameter respectively.