Phosphorus-containing heterocyclic cationic surfactants alkyldimethylphenylphospholium bromides with the alkyl chain length 14 to 18 carbon atoms were used for the stabilization of silver nanodispersions. Zeta potential of silver nanodispersions ranges from +35 to +70 mV, which indicates the formation of stable silver nanoparticles (AgNPs). Long-chain heptadecyl and octadecyl homologs of the surfactants series provided the most intensive stabilizing effect to AgNPs, resulting in high positive zeta potential values and smaller diameter of AgNPs in the range 50-60 nm. A comparison with non-heterocyclic alkyltrimethylphosphonium surfactants of the same alkyl chain length showed better stability and more positive zeta potential values for silver nanodispersions stabilized with heterocyclic phospholium surfactants. Investigations of biological activity of phospholium-capped AgNPs are represented by the studies of antimicrobial activity and cytotoxicity. While cytotoxicity results revealed an increased level of HepG2 cell growth inhibition as compared with the cytotoxicity level of silver-free surfactant solutions, no enhanced antimicrobial action of phospholium-capped AgNPs against microbial pathogens was observed. The comparison of cytotoxicity of AgNPs stabilized with various non-heterocyclic ammonium and phosphonium surfactants shows that AgNPs capped with heterocyclic alkyldimethylphenylphospholium and non-heterocyclic triphenyl-substituted phosphonium surfactants have the highest cytotoxicity among silver nanodispersions stabilized by the series of ammonium and phosphonium surfactants.
- Publikační typ
- časopisecké články MeSH
The present study is focused on the synthesis and investigation of the physicochemical and biological properties of silver nanoparticles stabilized with a series of cationic gemini surfactants having a polymethylene spacer of variable length. UV-VIS spectroscopy, dynamic light scattering, scanning electron microscopy and zeta potential measurements were applied to provide physicochemical characterization of the silver nanoparticles. The mean size values of the nanoparticles were found to be in the 50 to 115 nm range. From the nanoparticle size distributions and scanning electron microscopy images it results that a population of small nanoparticles with the size of several nanometers was confirmed if the nanoparticles were stabilized with gemini molecules with either a short methylene spacer (two or four -CH2- groups) or a long spacer (12 -CH2- groups). The average zeta potential value for silver nanoparticles stabilized with gemini molecules is roughly independent of gemini surfactant spacer length and is approx. +58 mV. An interaction model between silver nanoparticles and gemini molecules which reflects the gained experimental data, is suggested. Microbicidal activity determinations revealed that the silver nanoparticles stabilized with gemini surfactants are more efficient against Gram-negative bacteria and yeasts, which has a direct relation to the interaction mechanism of nanoparticles with the bacterial cell membrane and its structural composition.
CE methods have been developed for the chiral analysis of new types of six acyclic nucleoside phosphonates, nucleotide analogs bearing [(3-hydroxypropan-2-yl)-1H-1,2,3-triazol-4-yl]phosphonic acid, 2-[(diisopropoxyphosphonyl)methoxy]propanoic acid, or 2-(phosphonomethoxy)propanoic acid moieties attached to adenine, guanine, 2,6-diaminopurine, uracil, and 5-bromouracil nucleobases, using neutral and cationic cyclodextrins as chiral selectors. With the exception of the 5-bromouracil-derived acyclic nucleoside phosphonate with a 2-(phosphonomethoxy)propanoic acid side chain, the R and S enantiomers of the other five acyclic nucleoside phosphonates were successfully separated with sufficient resolutions, 1.51-2.94, within a reasonable time, 13-28 min, by CE in alkaline BGEs (50 mM sodium tetraborate adjusted with NaOH to pH 9.60, 9.85, and 10.30, respectively) containing 20 mg/mL β-cyclodextrin as the chiral selector. A baseline separation of the R and S enantiomers of the 5-bromouracil-derived acyclic nucleoside phosphonate with 2-(phosphonomethoxy)propanoic acid side chain was achieved within a short time of 7 min by CE in an acidic BGE (20:40 mM Tris/phosphate, pH 2.20) using 60 mg/mL quaternary ammonium β-cyclodextrin chiral selector. The developed methods were applied for the assessment of the enantiomeric purity of the above acyclic nucleoside phosphonates. The preparations of all these compounds were found to be synthesized in pure enantiomeric forms. Using UV absorption detection at 206 nm, their concentration detection limits were in the low micromolar range.
Predmetom publikácie je komplexné spektrálne a fyzikálno- chemické hodnotenie mono[{3-[4-(2-etoxyetoxy)- benzoyloxy]-2-hydroxypropyl}-terc-butylamónium] fumarátu, potenciálneho ultrakrátko pôsobiaceho blokátora ß1-adrenergných receptorov. Totožnosť hodnotenej zlúčeniny (pracovne označenej ako UPB-2) bola potvrdená 1H-, 13C-NMR a IR spektrami. V rámci stanovenia základných fyzikálno-chemických charakteristík bola určená hodnota teploty topenia, rozpustnosť v spektre rozpúšťadiel, čistota (adsorpčná chromatografia na tenkej vrstve), povrchová aktivita (nepriama Traubeho stalagmometrická metóda), acidobázické charakteristiky (hodnota pKa stanovená alkalimetrickou titráciou), hodnoty log ε (spektrofotometricky v UV/ /VIS oblasti), ako aj hodnotenie vplyvu kyslého a zásaditého prostredia na stabilitu UPB-2. Ďalšími experimentálne stanovenými parametrami boli lipohydrofilné deskriptory určené pomocou RP-HPLC (log k’), shake flask metódou stanovené hodnoty rozdeľovacích koeficientov Pexp (resp. log Pexp) v rôznych rozdeľovacích systémoch. Na základe log Pexp-údajov bola predpovedaná schopnosť UPB-2 prechádzať cez hematoencefalickú bariéru. Pre stanovenie obsahu UPB-2 bola aplikovaná RP-HPLC (reversed-phase HPLC) metóda vnútorného štandardu a UV/VIS spektrofotometria pri vlnovej dĺžke 260 nm (vodné prostredie) a 258 nm (prostredie metanolu).
The present paper aims at a complex spectral and physicochemical evaluation of mono[{3-[4-(2-ethoxyethoxy)- benzoyloxy]-2-hydroxypropyl}-tert-butylammonium] fumarate, the potential ultra-short acting blocker of ß1-adrenergic receptors. The identity of the evaluated compound (labelled as UPB-2) was confirmed by 1H-, 13C-NMR and IR spectral data as well. The estimated physicochemical parameters included melting point data, solubility in various media, purity checking (adsorption thin-layer chromatography), surface activity determination (non- -direct Traube stalagmometric method), acidobasic characteristics (pKa value determination by alkalimetric titration), log ε values estimation (spectrophotometrically in UV/VIS region) and a study of the influence of acidic and alkaline media towards the stability of UPB-2. Other experimentally estimated values were lipohydrophilic descriptors using RP- -HPLC (log k’) and the log Pexps in various lipohydrophilic media by the shake flask method. Based on the log Pexp readouts, the ability to permeate across the brain-blood barrier was predicted. For the content determination of UBP-2 the RP-HPLC (reversed-phase HPLC), the method of an internal standard and UV/VIS spectrophotometry at the wavelength of 260 nm (aqueous medium) and at 258 nm (methanolic medium) was applied.
Predmetom prezentovanej práce je komplexné spektrálne a fyzikálno-chemické hodnotenie mono[{3-[4-(2-etoxyetoxy)-benzoyloxy]-2-hydroxypropyl}-izopropylamónium]fumarátu, potenciálneho ultrakrátko pôsobiaceho ß1-blokátora. Totožnosť študovanej substancie (pracovne označenej ako UPB-1) bola potvrdená 1H- a 13C-NMR spektrami ako aj IR spektrometriou. Medzi stanovené základné fyzikálno-chemické charakteristiky patrilo určenie teploty topenia, rozpustnosti v spektre rozpúšťadiel, overenie čistoty (adsorpčná chromatografia na tenkej vrstve), určenie povrchovej aktivity (Traubeho stalagmometrická metóda), acidobázické charakteristiky (hodnota pKa pomocou alkalimetrickej titrácie), určenie hodnôt log ? s využitím spektrofotometrie v UV/VIS oblasti, ako aj hodnotenie vplyvu kyslého a zásaditého prostredia na stabilitu študovanej látky. Ďalšími experimentálne stanovenými parametrami boli lipohydrofilné charakteristiky pomocou RP-HPLC (log k’), shake flask metódou stanovené hodnoty rozdeľovacích koeficientov Pexp (resp. log Pexp) v rôznych lipohydrofilných prostrediach. Na základe log Pexp- dát sa predikovala schopnosť látky prechádzať cez hematoencefalickú bariéru. Pre stanovenie obsahu UPB-1 sa použila RP-HPLC (reversed-phase HPLC) metóda vnútorného štandardu a UV/VIS spektrofotometria pri vlnovej dĺžke 260 nm (vodné prostredie) a 258 nm (prostredie metanolu).
The present paper deals with a complex spectral and physicochemical evaluation of mono[{3-[4-?-(2-etoxyetoxy)-benzoyloxy]-2-hydroxypropyl}-isopropylammonium]fumarate, a potential ultrashort acting ß1-blocker. The identity of the substance under study (labelled as UPB-1) was confirmed by 1H- and 13C-NMR spectra as well as IR spectrometry. The determined fundamental physicochemical characteristics included the determination of the melting point, solubility in a spectrum of solvents, verification of purity (adsorption thin-layer chromatography), determination of surface activity (Traube’s stalagmometric method), acidobasic characteristics (pKa value by means of alkalimetric titration), determination of log ? values using spectrophotometry in UV/VIS region, as well as the evaluation of the effect of acid and basic media on the stability of the substance under the study. Other experimentally determined parameters were lipohydrophilic characteristics essayed by means of RP-HPLC (log k’), and the shake-flask method was employed to determine the values of the partition coefficients Pexp (resp. log Pexp) in different lipohydrophilic media. On the basis of log Pexp- data, the ability of the substance to penetrate the hematoencephalic barrier was predicted. To determine the UPB-1 content, RP-HPLC (reversed-phase HPLC) method of the internal standard and UV/VIS spectrophotometry at the wavelength of 260 nm (aqueous medium) and 258 nm (methanol medium) were used.
