Joanna Kurczewska

Molecular scavengers as carriers of analytes for mass spectrometry identification.

Storage and preconcentration of various molecules by molecular scavengers for thermal desorption and identification by mass spectrometry is presented. A dielectric barrier discharge ionization source combined with a heating element for the chemical characterization of amines and organic acids, initially trapped by molecular scavengers, is described. The developed technique can be applied for preconcentration of minute amounts of molecules in liquid and gaseous phases, as well as their transportation and thorough analysis. The method, operating at ambient pressure, can also be complementary to electron impact ionization, with no need for sample derivatization.

Copper removal by carbon nanomaterials bearing cyclam-functionalized silica

The synthesis of metal (Fe, Co, Ni)-encapsulated carbon nanomaterials coated with cyclam-bonded silica has been described. The organic layer was identified by Fourier transform infrared spectroscopy and elemental analysis. The functionalized magnetic nanomaterials were employed to extract the divalent cations: copper, calcium, cobalt, manganese and nickel from aqueous solutions. Their adsorption capacities were studied by the batch procedure. The concentration of cations extracted was determined by inductively coupled plasma mass spectrometry. Influence of different parameters viz. pH, amount of the compound studied, contact time, on the cation extraction was investigated. Under optimum conditions copper extraction was significantly more efficient when compared with other coexisting ions.

Halloysite nanotubes as carriers of vancomycin in alginate-based wound dressing

The influence of an inorganic support – halloysite nanotubes – on the release rate and biological activity of the antibiotic encapsulated in alginate-based dressings was studied. The halloysite samples were loaded with approx. 10 wt.% of the antibiotic and then encapsulated in Alginate and Gelatin/Alginate gels. The material functionalized with aliphatic amine significantly extended the release of vancomycin from alginate-based gels as compared to that achieved when silica was used. After 24 h, the released amounts of the antibiotic immobilized at silica reached 70%, while for the drug immobilized at halloysite the released amount of vancomycin reached 44% for Alginate discs. The addition of gelatin resulted in even more prolonged sustained release of the drug. The antibiotic was released from the system with a double barrier with Higuchi kinetic model and Fickian diffusion mechanism. Only the immobilized drug encapsulated in Alginate gel demonstrated very good antimicrobial activity against various bacteria. The inhibition zones were greater than those of the standard discs for the staphylococci and enterococci bacteria tested. The addition of gelatin adversely affected the biological activity of the system. The inhibition zones were smaller than those of the reference samples. A reduction in the drug dose by half had no significant effect on changing the release rate and microbiological activity. The in vivo toxicity studies of the material with immobilized drug were carried out with Acutodesmus acuminatus and Daphnia magna. The material studied had no effect on the living organisms used in the bioassays. The proposed system with a double barrier demonstrated high storage stability.

Synthesis of Silica Chemically Bonded with Poly(Ethylene Oxide) 4-Arm, Amine-Terminated for Copper Cation Removal

Chemically modified silica containing a poly(ethylene oxide) 4-arm, amine-terminated unit has been obtained in the multi-step synthesis. The synthesized material was characterized by elemental, thermogravimetric analysis and infrared spectroscopy. The surface morphology was analyzed by scanning electron microscopy. The support studied was applied for selective extraction of copper(II) [Cu(II)] from water solutions. The influence of different parameters (pH, amount of the support studied, and contact time) on the copper extraction was investigated. At the optimum conditions, the copper extraction was approximately 90%, significantly greater than that of the other coexisting ions--nickel(II) [Ni(II)], cobalt(II) [Co(II)], and manganese(II) [Mn(II)]. The exception was calcium(II) [Ca(II)], which reached 30% of the extraction percentage. The solid support retained its properties after treatment with different organic and inorganic solvents. The recovery of adsorbed Cu(II) ions was approximately 97%. The sorbent studied can be applied effectively for the pre-concentration of a low level of Cu(II) in the different water samples.

Adsorption of metal ions on magnetic carbon nanomaterials bearing chitosan-functionalized silica

Abstract Magnetic chitosan nanocomposites have been synthesized on the basis of metal (Fe, Co, Ni)-encapsulated carbon nanomaterials. The organic layer was identified using Fourier transform infrared spectroscopy and elemental analysis. The functionalized nanomaterials were employed to remove metal ions: cadmium, copper, nickel, lead and zinc from aqueous solutions. Their adsorption capacities were studied by the batch procedure. The concentration of cations extracted was determined by inductively coupled plasma mass spectrometry. The influence of different parameters (pH, amount of the support studied, contact time) on the cation extraction was investigated. The studies demonstrated excellent ability of copper and lead adsorption, and satisfactory adsorption of other ions applied by the supports studied. The nanocomposites with complexed cations can be easily removed from water with the help of an external magnet. They can then undergo regeneration in an acidic environment and can be reused in the analogous process repeatedly.

Silica surface modified by aliphatic amines as effective copper complexing agents

Abstract Silica surface was modified with four aliphatic acyclic amines differing in the number of nitrogen donor atoms and the chain length. The structures of the four systems were confirmed by Fourier transform infrared spectroscopy. Three of the systems studied were found to show excellent scavenging of copper ions and relatively weaker of nickel ions from the water solutions. The complexing abilities were monitored by ultraviolet and visible measurements. Standard colorimetric methods of element determination were used to observe the absorbance decrease at the maximum wavelength in the presence of the compounds studied. The influence of pH of the aqueous solution, the amount of modified silica, the stirring time and the selectivity with respect to other metal ions was investigated.

Will the use of double barrier result in sustained release of vancomycin? Optimization of parameters for preparation of a new antibacterial alginate-based modern dressing.

The aim of this research was to prepare and characterize an alginate-based wound dressing containing vancomycin immobilized at the silica surface. The silica samples functionalized with amine, diol and carboxylic acid groups were loaded with 7.8, 5.7 and 7.1wt.% of the antibiotic respectively. The immobilized drug was encapsulated in alginate or gelatin/alginate gels and the average concentration of vancomycin was about 10mg per g of the dried gel. The effect of functional organic groups at the silica surface on the release rate of the drug was investigated. Only the drug immobilized at Si-amine in alginate matrix was found to demonstrate slower release from the proposed wound dressing. The in vitro release profiles for other silica carriers did not show significant differences in relation to the free loaded drug. The presence of gelatin had a favourable impact on the slowing down of the drug release from the dressing with a double barrier. All the gels studied with vancomycin immobilized at the silica surface demonstrated antimicrobial activity against various bacteria. A reduction of the drug dose to a half had no effect on changing microbiological activity of gels.

The bifunctionality of silica gel modified with Congo red

AbstractSilica gel was chemically modified with Congo red and characterized by Fourier transform infrared spectroscopy, elemental and thermogravimetric analysis. The pH-sensitive immobilized Congo red retains the same properties as its solution counterpart and could be applied as solid indicator. The functionalized silica gel was also employed to extract different cations from water solutions. The concentration of cations extracted was determined by inductively coupled plasma optical emission spectrometry. The solid support is able to selectively extract silver and copper from water solutions and retains its properties after treatment with different organic and inorganic solvents.

Binding of Industrial Deposits of Heavy Metals and Arsenic in the Soil by 3-Aminopropyltrimethoxysilane

Abstract The results of the research studies concerning binding of heavy metals and arsenic (HM+As), occurring in soils affected by emissions from Głogów Copper Smelter and Refinery, by silane nanomaterial have been described. The content of heavy metals and arsenic was determined by AAS and the effectiveness of heavy metals and arsenic binding by 3-Aminopropyltrimethoxysilane was examined. The total leaching level of impurities in those fractions was 73.26% Cu, 74.7% – Pb, 79.5% Zn, 65.81% – Cd and 55.55% As. The studies demonstrated that the total binding of heavy metals and arsenic with nanomaterial in all fractions was about as follows: 20.5% Cu, 9.5% Pb, 7.1% Zn, 25.3% Cd and 10.89% As. The results presented how the safety of food can be cultivated around industrial area, as the currently used soil stabilization technique of HM by soil pH does not guarantee their stable blocking in a sorptive complex.

Double barrier as an effective method for slower delivery rate of ibuprofen

Ibuprofen (IBU) was chosen as a model drug to investigate the drug delivery rate. Mesoporous MCM-41 has been charged with ibuprofen (MCM-41_IBU). Calcium alginate was applied to encapsulate free drug and the mesoporous material. The system with double barrier demonstrated a slower release of IBU than free ibuprofen-loaded alginate beads and MCM-41_IBU. The IBU release from alginate matrix can be controlled by adjusting the free IBU/MCM-41_IBU ratio.