Copolymerization of limonene oxide and cyclic anhydrides catalyzed by ionic liquid BMI·Fe2Cl7, nanoparticles preparation, crosslinking, and cytotoxicity studies

Aprotic ionic liquids have been recognized as the potential electrolytes for electrodeposition of various metals due to wide electrochemical potential window and intrinsic ionic conductivity. In addition, the ability of the ionic liquids to disperse variety of nanomaterials without any stabilizing reagents makes it possible to prepare metal nanoparticles simply by electrochemical reduction of metal species dissolved in the ionic liquids. We have already reported the electrochemical preparation of the metal nanoparticles of such transition metals as Fe, Co, Ni, Pd, Ag, Cd, Pt, and Au in some ionic liquids composed of bis(trifluoromethylsulfonyl)amide (TFSA–) and dialkylpyrrolidinium cations.1-10 The average size of the nanoparticles prepared in the ionic liquids was found to be a few nanometers. However, the factors determining the average size of the nanoparticles have not been clarified yet. In the present study, the effects of the cations and anions on the size distribution of Pd nanoparticles has been investigated in the TFSA–- and FSA– (bis(fluorosulfonyl)amide)-based ionic liquids. The TFSA–-based ionic liquids composed of 1-butyl-, 1-hexyl-, and 1-decylpyrrolidinium (BMP+, HMP+, and DMP+) with bromides of the corresponding organic cations were used as the electrolytes. BMPFSA was prepared by the metathesis reaction of BMPBr and LiFSA. PdBr2 was dissolved in the electrolyte as a Pd(II) source. Glassy carbon was used as a working electrode. A rotating glassy carbon electrode was also used as a working electrode. A platinum wire was used as a counter electrode. A silver wire immersed in 0.1 M AgCF3SO3/BMPTFSA was used as a reference electrode. Pd nanoparticles were prepared by potentiostatic cathodic reduction using a double-compartment cell. The nanoparticles dispersed in the ionic liquids were characterized by transmission electron microscopy. Potentiostatic cathodic reduction on a GC electrode in BMPTFSA containing [PdCl4]2– resulted in deposition of Pd metal on the electrode and formation of Pd nanoparticles dispersed in the ionic liquid. The amount of Pd deposited on the GC electrode in BMPTFSA decreased with lowering the electrode potential, indicating the adsorption of Pd atom formed at the electrode-electrolyte interface onto the electrode surface is considered to be inhibited by accumulation of BMP+ at the interface at negative potentials.1 Pd nanoparticles were prepared using a rotating GC electrode with different rotating rates in order to examine the effects of the current density on the average size of Pd nanoparticles. The average size of Pd nanoparticles prepared at –2.5 V in 10 mM [PdBr4]2–/BMPTFSA was independent of the rotating rate, indicating the supply rate of Pd atoms at the electrode surface has no influence on the average size of Pd nanoparticles.10 The average size of Pd nanoparticles prepared in BMPTFSA, HMPTFSA, and DMPTFSA increased with an increase in the alkyl chain length of the cation.7 In addition, the average size of Pd nanoparticles prepared in BMPTFSA with excess Br–or in BMPFSA was smaller than that in BMPTFSA. These results suggested that the average size of Pd nanoparticles is mainly affected not by the current density and the electrode potential but by the size of the cations and anions composing the ionic liquids. References R. Fukui, Y. Katayama, and T. Miura, J. Electrochem. Soc., 158, D567 (2011). Y.-L. Zhu, Y. Katayama, and T. Miura, Electrochem. Solid-State Lett., 14, D110 (2011). Y. Katayama, R. Fukui, and T. Miura, Electrochemistry, 81, 532 (2013). Y. Katayama, T. Endo, T. Miura and K. Toshima, J. Electrochem. Soc., 160, D423 (2013). Y. Katayama, T. Endo, T. Miura, and K. Toshima, J. Electrochem. Soc., 161, D87 (2014). K. Yoshii, Y. Oshino, N. Tachikawa, K. Toshima, and Y. Katayama, Electrochem. Commun., 52, 21 (2015). Y. Katayama, Y. Oshino, N. Ichihashi, N. Tachikawa, K. Yoshii, and K. Toshima, Electrochim. Acta,183, 37 (2015). S. Saha, T. Taguchi, N. Tachikawa, K. Yoshii, Y. Katayama, Electrochim. Acta,183, 42 (2015). S. Sultana, N. Tachikawa, K. Yoshii, L. Magagnin, K. Toshima, and Y. Katayama, J. Electrochem. Soc., 163, D401 (2016). S. Sultana, N. Tachikawa, K. Yoshi, K. Toshima, L. Magagnin, and Y. Katayama, Electrochim. Acta, 249, 263 (2017).

Microemulsion system constructed with a new cyano-functionalized ionic liquid for the extraction of Pd(II) and preparation of palladium nanoparticles

Electrochemical preparation of palladium nanoparticles in bis(trifluoromethylsulfonyl)amide ionic liquids consisting of pyrrolidinium cations with different alkyl chain lengths

Hydrogen is widely used as a fuel for fuel cells but presents safety concerns and challenges in transportation. In contrast, urea has emerged as a promising alternative due to its high energy density and stability under atmospheric conditions.[1] It has been reported that nickel (Ni) exhibited high electrocatalytic activity for urea oxidation.[2,3] While Ni-based alloy catalysts have shown electrocatalytic activity for urea oxidation (UOR), there has been limited research on improving the activity through alloying or combining Ni with noble metals. Recently we reported the preparation of noble metal nanoparticles (NPs) by metal sputtering deposition onto ionic liquid (IL) under reduced pressure (IL/metal sputtering technique). Thus-obtained NPs were uniformly and stably dispersed without additional stabilizing agents.[4] This technique enabled the preparation of alloy metal NPs, such as AuPd and AuRh, through simultaneous sputtering of corresponding pure metals.[5,6] In this study, we focus on the preparation of ternary Ni-Pt-Ir alloy NPs via IL/metal sputtering and evaluate their electrocatalytic activity for urea oxidation (UOR) was evaluated.The simultaneous deposition of Ni, Pt, and Ir onto an IL of N,N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium tetrafluoroborate (DEME-BF4) was achieved by sputtering multi-component target composed of pure metal plates of Ni, Pt, and Ir under an argon pressure of 10 Pa. The resulting IL containing NPs was mixed with carbon black (CB) powders and subjected to heat treatment at 300°C under a nitrogen atmosphere for 30 minutes to load NiPtIr NPs onto CB particles (NiPtIr/CB). The activity of NiPtIr/CB for urea oxidation was evaluated in a 1 M KOH aqueous solution containing 0.33 M urea.TEM measurements and EDX analysis revealed that spherical NPs with the particle size of 1-2 nm, consisting of Ni, Pt, and Ir, were deposited in the IL. Loading these NPs on CB enlarged the particle size to 3-5 nm. XRD patterns of NiPtIr/CB indicated the shift of diffraction peaks to higher angles with increasing Ni content, confirming the formation of NiPtIr alloy. The electrochemically active surface area (ECSA) of Ni was determined by cyclic voltammetry. The UOR reaction current was observed at the potential more positive than 0.37 V vs. Ag/AgCl. The UOR activity was evaluated from the current at 0.5 V vs. Ag/AgCl normalized by ECSA. The UOR activities of NiPtIr/CB were smaller than that of Ni/CB when the Ni fraction exceeded 30%. However, the NiPtIr/CB catalysts with the Ni fraction of < ca.20% exhibited higher activity for UOR compared to the Ni/CB. The activity was optimal for Ni-Pt-Ir/CB with a 9% Ni fraction. XPS spectra revealed the change in the Ni species on the catalyst surface, contributing to the improvement of UOR activity with the change in the catalyst composition. In conclusion, we successfully prepared NiPtIr ternary alloy NPs using the IL/metal sputtering technique and demonstrated their UOR activity depending on the composition of the catalyst particles.

Preparation of albumin nanoparticles in water-in-ionic liquid microemulsions

Bismuth(III) furfuryl based dithiocarbamates: Synthesis, structures, biological activities and their utility for the preparation of Bi2S3 and Bi2O3 nanoparticles

Ultrasonic-assisted preparation and characterization of CdS nanoparticles in the presence of a halide-free and low-cost ionic liquid and photocatalytic activity

Room temperature ionic liquids (RTILs) are unique in many respects. The preparation method reported here is based on their extremely low vapour pressure that allows for their usage in vacuum. By magnetron sputtering of nickel or by co-sputtering of Ni-Fe or Ag-Cu on a surface of several imidazolium-based RTILs, we prepared nanocolloids containing metallic nanoparticles ranging in size from 6 to 30 nm, depending on the kind of RTIL, with low size dispersion. The nanocolloids are stable in time, no sedimentation or agglomeration was observed after two years. The method can be used also for preparation of the nanoparticles from semiconducting or insulating materials. As the next step, nanocolloids prepared in this way can be used for decoration of thin-film gas sensors by proper nanoparticles aiming at enhancement of their sensitivity and selectivity. Two ways of immobilization are presented - mild heating of a drop of colloid containing Ni-Fe nanoparticles placed on TEM mesh, and Ag-Cu nanoparticles that were immobilized on the surface of gold thin-film electrode by electrophoresis.

Preparation and characterization of teniposide PLGA nanoparticles and their uptake in human glioblastoma U87MG cells

Background: Smart nanoparticulate materials, namely tailored nanoparticles (NPs) with specific surface functionality, have recently attracted attention as useful tool for time- and site-specific drug delivery. Specifically, polymeric nanoparticles (NPs) can be chemically functionalized with different chemical entities, i.e. peptides, that selectively recognize biological substrates in vivo and target drug release. Divergent and very complex strategies can be pursued in order to obtain peptidedecorated NPs. Methods: A simple method was suggested for direct functionalization of poly-lactide-co-glicolide (PLGA) with small peptides. A solid-phase peptide synthesis was used to obtain a dodecapeptide (GE11) and a smaller tetrapeptide (FQPV). FQPV- and GE11-PLGA conjugates were obtained by optimized carbodiimide chemistry. Nanoprecipitation and solvent extraction/evaporation methods were purpose-built in order to prepare FQPV-PLGA NPs. NPs were characterized in terms of size, surface charge and adsorbed peptide amount; ex-vivo cytotoxicity studies were performed on FQPV-PLA NPs using adult fibroblasts. Results: Custom GE11, recently known as efficient Epidermal Growth Factor Receptor targeting agent, and FQPV, used as model peptide, were synthesized by solid-phase peptide synthesis achieving good purity (95%) and satisfactory process yields (70-85%). Then, FQPV- and GE11-PLGA conjugates were obtained by optimized carbodiimide chemistry achieving an high degree of functionalization (> 85%). Aware of different physico-chemical properties of peptide-PLGA conjugates with respect to plain PLGA, two different NPs preparation techniques, nanoprecipitation and solvent extraction/ evaporation methods, were purpose-built in order to prepare FQPV-PLGA NPs. Both methods revealed suitable to obtain NPs with proper dimensions for the parenteral administration (< 250nm), narrow size distribution (P.I. about 0.1), good morphological features and negative charge (about –20mV). A peptide adsorption protocol onto NPs was considered as additional strategy to increase peptide expression on NPs surface aimed at improving the targeting effectiveness. A Design of Experiment approach (DoE) has been successfully applied to the more versatile solvent extraction/ evaporation method in order to systematically highlight the influence of process parameters (organic solvent mixture, PVA concentration and polymeric solution volume) on NPs sizes. Conclusion: PLGA was successfully functionalized with two different peptides, FQPV and GE11, following the a versatile and simple carbodiimmide chemistry without further modifying polymer and/or peptide structure. Both nanoprecipitation and solvent extraction/evaporation NPs preparation methods were properly optimized in order to obtain peptide-PLGA based NPs and they can be alternatively selected according to solubility properties of both peptide-polymer conjugate and drug intended for encapsulation. Peptide adsorption on preformed PLGA NPs could be efficiently used to increase peptide expression on NPs surface thus improving cellular recognition in case of active targeting. Preliminary cytocompatibility evaluation of the selected peptide-PLGA based nanoparticulate materials shows a potential feasibility of the set-up synthetic procedures and NPs preparation methods for pharmaceutical purposes. Keywords: FQPV-PLGA nanoparticles, GE11-PLGA nanoparticles, peptide synthesis, peptide-PLGA conjugates, peptidepolymer conjugate synthesis, PLGA nanoparticles, smart PLGA nanomaterials.

The preparation of polymer nanoparticles containing reduced graphene oxide nanosheets (rGO) within their interior has been conducted by radical polymerization in aqueous miniemulsion employing the nonionic surfactant Tween 80. Polymerizations were conducted using the ionic liquid monomer 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)amide ([Veim][TFSA]) as well as mixtures of this monomer with ethyl methacrylate (EMA). [Veim][TFSA] plays an important role in that it provides stabilization of rGO monomer dispersions, presumably via π–π interactions between rGO and [Veim][TFSA]. If the EMA:[Veim][TFSA] ratio is too high, rGO precipitates during preparation of the monomer phase of the miniemulsion. Interestingly, it was demonstrated that addition of a small amount of the homopolymer of [Veim][TFSA] leads to significantly improved rGO stability (more so than the effect of [Veim][TFSA] monomer), thus enabling preparation of polymer nanoparticles containing higher amounts of EMA.

Zirconia nanoparticles were prepared in ionic liquid BMIMBF4-water using zirconium salt (ZrOCl2•8H2O), urea as raw material by hydrothermal synthesis method. The structure and morphology of zirconia were characterized by XRD and TEM. The experimental results showed zirconia nanoparticles could be prepared at 170°C for 24 hours in a hydrothermal kettle. Its size was about 10-30nm and the particles dispersed uniformly, and had no agglomeration phenomenon.

The aim of this study was the preparation of novel polyester nanoparticles based on folic acid (FA)-functionalized poly(ethylene glycol)-poly(propylene succinate) (PEG-PPSu) copolymer and loaded with the new anticancer drug ixabepilone (IXA). These nanoparticles may serve as a more selective (targeted) treatment of breast cancer tumors overexpressing the folate receptor. The synthesized materials were characterized by (1)H-NMR, FTIR, XRD and DSC. The nanoparticles were prepared by a double emulsification and solvent evaporation method and characterized with regard to their morphology by scanning electron microscopy, drug loading with HPLC-UV and size by dynamic light scattering. An average size of 195 nm and satisfactory drug loading efficiency (3.5%) were observed. XRD data indicated that IXA was incorporated into nanoparticles in amorphous form. The nanoparticles exhibited sustained drug release properties in vitro. Based on in vitro cytotoxicity studies, the blank FA-PEG-PPSu nanoparticles were found to be non-toxic to the cells. Fluorescent nanoparticles were prepared by conjugating Rhodanine B to PEG-PPSu, and live cell, fluorescence, confocal microscopy was applied in order to demonstrate the ability of FA-PEG-PPSu nanoparticles to enter into human breast cancer cells expressing the folate receptor.

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Platinum, palladium and rhodium nanoparticles stabilized by poly(N-vinyl-2-pyrrolidone) (PVP) can be synthesized by ethanolic reduction of the corresponding metal halide salts and when immobilized in an ionic liquid, 1-n-butyl-3-methylimidazolium hexafluorophosphate ([BMI][PF6]), are very effective olefin hydrogenation catalysts which are capable of being recycled by a simple decantation procedure without loss of activity.