Modification of Magnetite Nanoparticles with Triazine-Based Dendrons and Their Application as Drug-Transporting Systems.

The following research aims at the synthesis of magnetite nanoparticles functionalized with triazine-based dendrons and the application of the obtained materials as effective sorptive materials dedicated to acidic bioactive compounds. The adopted synthetic approach involved: (1) the synthesis of nanosized Fe3O4 particles via classic co-precipitation method, (2) the introduction of amine groups on their surface leading to materials' precursor, and (3) the final synthesis of branched triazine-based dendrons on the support surface by an iterative reaction between cyanuric chloride (CC) and piperazine (p) or diethylenetriamine (DETA) via nucleophilic substitution. The characterized materials were tested for their adsorptive properties towards folic acid, 18ß-glycyrrhetinic acid, and vancomycin, showing high adsorption capacities varying in the ranges of 53.33-401.61, 75.82-223.71, and 68.17-132.45 mg g-1, respectively. The formed material-drug complexes were also characterized for the drug-delivery potential, performed as in vitro release studies at pH 2.0 and 7.4, which mimics the physiological conditions. The release profiles showed that the proposed materials are able to deliver up to 95.2% of the drugs within 48 h, which makes them efficient candidates for further biomedical applications.

Salts of purine alkaloids caffeine and theobromine with 2,6-dihydroxybenzoic acid as coformer: structural, theoretical, thermal and spectroscopic studies.

The study of various forms of pharmaceutical substances with specific physicochemical properties suitable for putting them on the market is one of the elements of research in the pharmaceutical industry. A large proportion of active pharmaceutical ingredients (APIs) occur in the salt form. The use of an acidic coformer with a given structure and a suitable pKa value towards purine alkaloids containing a basic imidazole N atom can lead to salt formation. In this work, 2,6-dihydroxybenzoic acid (26DHBA) was used for cocrystallization of theobromine (TBR) and caffeine (CAF). Two novel salts, namely, theobrominium 2,6-dihydroxybenzoate, C7H9N4O2+·C7H5O4- (I), and caffeinium 2,6-dihydroxybenzoate, C8H11N4O2+·C7H5O4- (II), were synthesized. Both salts were obtained independently by slow evaporation from solution, by neat grinding and also by microwave-assisted slurry cocrystallization. Powder X-ray diffraction measurements proved the formation of the new substances. Single-crystal X-ray diffraction studies confirmed proton transfer between the given alkaloid and 26DHBA, and the formation of N-H...O hydrogen bonds in both I and II. Unlike the caffeine cations in II, the theobromine cations in I are paired by noncovalent N-H...O=C interactions and a cyclic array is observed. As expected, the two hydroxy groups in the 26DHBA anion in both salts are involved in two intramolecular O-H...O hydrogen bonds. C-H...O and π-π interactions further stabilize the crystal structures of both compounds. Steady-state UV-Vis spectroscopy showed changes in the water solubility of xanthines after ionizable complex formation. The obtained salts I and II were also characterized by theoretical calculations, Fourier-transform IR spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and elemental analysis.

The Electrospray (ESI) and Flowing Atmosphere-Pressure Afterglow (FAPA) Mass Spectrometry Studies of Nitrophenols (Plant Growth Stimulants) Removed Using Strong Base-Functionalized Materials.

The functional silica-based materials functionalized with a strong nitrogen base TBD (SiO2-TBD) deposited via a linker or with a basic poly(amidoamine) dendrimer containing multiple terminal amine groups -NH2 (SiO2-EDA) and functional polymers containing a strong phosphazene base (Polymer-Phosphazene) or another basic poly(amidoamine) dendrimer (PMVEAMA-PAMAM) were tested as sorbents dedicated to a mixture of nitrophenols (p-nitrophenol and 2-methoxy-5-nitrophenol), which are analogs of nitrophenols used in plant growth biostimulants. The adsorptive potential of the studied materials reached 0.102, 0.089, 0.140, and 0.074 g of the nitrophenols g-1, for SiO2-TBD, SiO2-EDA, polymer-phosphazene, and PMVEAMA-PAMAM, respectively. The sorptive efficiency of the analytes, i.e., their adsorption on the functional materials, the desorption from the obtained [(sorbent)H+ - nitrophenolates-] complexes, and interactions with the used soil, were monitored using mass spectrometry (MS) technique with electrospray (ESI) and flowing atmosphere-pressure afterglow (FAPA) ionizations, for the analysis of the aqueous solutions and the solids, respectively. The results showed that the adsorption/desorption progress is determined by the structures of the terminal basic domains anchored to the materials, which are connected with the strength of the proton exchange between the sorbents and nitrophenols. Moreover, the conducted comprehensive MS analyses, performed for both solid and aqueous samples, gave a broad insight into the interactions of the biostimulants and the presented functional materials.

Mass Spectrometric Investigation of Organo-Functionalized Magnetic Nanoparticles Binding Properties toward Chalcones.

Chalcones are naturally occurring compounds exhibiting multiple biological functions related to their structure. The investigation of complexes formed by chalcones, namely 2',4'-dihydroxy-2-methoxychalcone (DH-2-MC) and 2',4'-dihydroxy-3-methoxychalcone (DH-3-MC), with organo-functionalized Fe3O4 magnetic nanoparticles using mass spectrometric techniques is reported. The magnetic nanoparticles were obtained by the silanization of Fe3O4 particles with 3-aminopropyltrimethosysilane, which were subsequently reacted with 3-hydroxybenzaldehyde (3-HBA) or 2-pyridinecarboxaldehyde (2-PCA), resulting in the formation of Schiff base derivatives. The formation of their complexes with chalcones was studied using electrospray (ESI) and flowing atmosphere-pressure afterglow (FAPA) mass spectrometric (MS) ionization techniques. The functional nanoparticles which were synthesized using 3-hydroxybenzaldehyde displayed higher affinity towards examined chalcones than their counterparts obtained using 2-pyridinecarboxaldehyde, which has been proved by both ESI and FAPA techniques. For the examined chalcones, two calibration curves were obtained using the ESI-MS method, which allowed for the quantitative analysis of the performed adsorption processes. The presence of Cu(II) ions in the system significantly hindered the formation of material-chalcone complexes, which was proved by the ESI and FAPA techniques. These results indicate that both mass spectrometric techniques used in our study possess a large potential for the investigation of the binding properties of various functional nanoparticles.

Deferoxamine-Modified Hybrid Materials for Direct Chelation of Fe(III) Ions from Aqueous Solutions and Indication of the Competitiveness of In Vitro Complexing toward a Biological System.

Deferoxamine (DFO) is one of the most potent iron ion complexing agent belonging to a class of trihydroxamic acids. The extremely high stability constant of the DFO-Fe complex (log ß = 30.6) prompts the use of deferoxamine as a targeted receptor for scavenging Fe(III) ions. The following study aimed at deferoxamine immobilization on three different supports: poly(methyl vinyl ether-alt-maleic anhydride), silica particles, and magnetite nanoparticles, leading to a class of hybrid materials exhibiting effectiveness in ferric ion adsorption. The formed deferoxamine-loaded hybrid materials were characterized with several analytical techniques. Their adsorptive properties toward Fe(III) ions in aqueous samples, including pH-dependence, isothermal, kinetic, and thermodynamic experiments, were investigated. The materials were described with high values of maximal adsorption capacity q m, which varied between 87.41 and 140.65 mg g-1, indicating the high adsorptive potential of the DFO-functionalized materials. The adsorption processes were also described as intense, endothermic, and spontaneous. Moreover, an exemplary magnetically active deferoxamine-modified material has been proven for competitive in vitro binding of ferric ions from the biological complex protoporphyrin IX-Fe(III), which may lead to a further examination of the materials' biological or medical applicability.

Adsorption and selectivity studies of direct and magnetite-cored molecularly imprinted polymers (MIPs and magMIPs) towards chosen chalcones investigated with various analytical methods.

The following article presents a method for obtaining molecularly imprinted polymers (MIPs) dedicated to trans-chalcone (TC) and 2',4'-dihydroxy-3-methoxychalcone (DHMC). The synthetic protocol optimized with a choice of the most suitable functional monomer led to the synthesis of MIPs and their non-imprinted equivalents (NIP) performed via direct polymerization or on the surface of magnetite nanoparticles. The characterized materials were investigated for adsorption isotherms of TC and DHMC, which led to satisfactory values of maximal adsorption capacity, reaching 131.58 and 474.71 mg g-1, respectively. Moreover, all the polymers were studied for the adsorption kinetics and the selectivity towards four structurally different chalcones, which proved the proper selectiveness towards the template molecules. Also, the kinetic profiles of chalcones' adsorption on the synthesized MIPs showed a quasi-plateau reached already after 2 hours, indicating high sorption effectiveness. The studies involved the use of various analytical techniques, which afforded a comprehensive and reliable description of the materials' adsorption efficacy. It was found that the materials successfully bind the MIP-complementary analytes and also structurally similar chalcones, with slightly lower intensity.

Dendrimer-Functionalized Hybrid Materials Based on Silica as Novel Carriers of Bioactive Acids.

One of the major goals in the materials science is the design and development of non-toxic, versatile, and efficient drug delivery systems. The study reported in this paper concerns the syntheses of poly(amidoamine) (PAMAM) dendrimers with tris(2-aminoethyl)amine as an amine core and different terminal amines, and their attachment to silica matrix. The obtained ethylenediamine (EDA), triethylenetetramine (TETA), tris(2-aminoethyl)amine (TREN) and 4,7,10-trioxa-1,13-tridecanediamine (TRI-OXA) dendrimers were introduced to the support surface via an epoxy linker, leading to a loading efficiency in the range of 0.054-0.113 mmol g-1, determined using elemental and thermogravimetric analyses. The materials exhibited high adsorption capacities towards the chosen model drugs: folic, salicylic and nicotinic acid. The investigated adsorption processes were found to follow the Freundlich isotherm model, with indication of the drugs' structure influence on the binding efficiency. Drug-loaded hybrid materials were also described for in vitro drug release in three pH-different paraphysiological media. The highest percentage release was obtained in the tests performed at pH 2.0, ranging between 35.42 and 99.83%. Satisfactory results and the versatility of PAMAM dendrimers may lead to the application of such materials not only as drug carriers dedicated to a wide range of pharmaceutics, but also as analytical tools for pre-concentration and/or the determination of biocompound contamination in samples.

Photoacoustic Spectroscopy of Surface-Functionalized Fe3O4-SiO2 Nanoparticles.

A permanent development of hybrid materials based on the highly absorptive or opaque materials has prompted a need of analytical tools, which are able to overcome obstacles connected with their physicochemical features. Iron oxide (II, III) (Fe3O4) nanoparticles gained a huge attention as supporters, as they are not only easily accessible using various synthetic approaches, but they also exhibit homogeneity and paramagnetic properties, which make them easily separable materials. Nevertheless, the classic infrared spectroscopic studies might meet several problems with characterization of such systems. Therefore, infrared spectroscopy in photoacoustic mode using Fourier transform infrared-photoacoustic infrared spectroscopy (FT-IR PAS) can be an extremely sensitive and exact analytical tool for investigation of the magnetite-based hybrid material surface. Herein, we present a synthesis of Fe3O4 nanoparticles using co-precipitation method with their subsequent encapsulation within silica matrix decorated with different silanes containing various terminal functional groups. The proper syntheses of core/shell structures were confirmed using the FT-IR PAS method. Each spectrum exhibited specific bands corresponding to vibrations of magnetite particles, silica lattice, and particular surface functional groups, which strictly indicated successful grafting of silanes onto Fe3O4 surface.