Cellulose-Amine Porous Materials: The Effect of Activation Method on Structure, Textural Properties, CO2 Capture, and Recyclability.

CO2 capture via physical adsorption on activated porous carbons represents a promising solution towards effective carbon emission mitigation. Additionally, production costs can be further decreased by utilising biomass as the main precursor and applying energy-efficient activation. In this work, we developed novel cellulose-based activated carbons modified with amines (diethylenetriamine (DETA), 1,2-bis(3-aminopropylamino)ethane (BAPE), and melamine (MELA)) with different numbers of nitrogen atoms as in situ N-doping precursors. We investigated the effect of hydrothermal and thermal activation on the development of their physicochemical properties, which significantly influence the resulting CO2 adsorption capacity. This process entailed an initial hydrothermal activation of biomass precursor and amines at 240 °C, resulting in C+DETA, C+BAPE and C+MELA materials. Thermal samples (C+DETA (P), C+BAPE (P), and C+MELA (P)) were synthesised from hydrothermal materials by subsequent KOH chemical activation and pyrolysis in an inert argon atmosphere. Their chemical and structural properties were characterised using elemental analysis (CHN), infrared spectroscopy (IR), scanning electron microscopy (SEM), and thermogravimetric analysis (TG). The calculated specific surface areas (SBET) for thermal products showed higher values (998 m2 g-1 for C+DETA (P), 1076 m2 g-1 for C+BAPE (P), and 1348 m2 g-1 for C+MELA (P)) compared to the hydrothermal products (769 m2 g-1 for C+DETA, 833 m2 g-1 for C+BAPE, and 1079 m2 g-1 for C+MELA). Carbon dioxide adsorption as measured by volumetric and gravimetric methods at 0 and 25 °C, respectively, showed the opposite trend, which can be attributed to the reduced content of primary adsorption sites in the form of amine groups in thermal products. N2 and CO2 adsorption measurements were carried out on hydrothermal (C) and pyrolysed cellulose (C (P)), which showed a several-fold reduction in adsorption properties compared to amine-modified materials. The recyclability of C+MELA, which showed the highest CO2 adsorption capacity (7.34 mmol g-1), was studied using argon purging and thermal regeneration over five adsorption/desorption cycles.

Acridine Based N-Acylhydrazone Derivatives as Potential Anticancer Agents: Synthesis, Characterization and ctDNA/HSA Spectroscopic Binding Properties.

A series of novel acridine N-acylhydrazone derivatives have been synthesized as potential topoisomerase I/II inhibitors, and their binding (calf thymus DNA­ctDNA and human serum albumin­HSA) and biological activities as potential anticancer agents on proliferation of A549 and CCD-18Co have been evaluated. The acridine-DNA complex 3b (-F) displayed the highest Kb value (Kb = 3.18 × 103 M−1). The HSA-derivatives interactions were studied by fluorescence quenching spectra. This method was used for the calculation of characteristic binding parameters. In the presence of warfarin, the binding constant values were found to decrease (KSV = 2.26 M−1, Kb = 2.54 M−1), suggesting that derivative 3a could bind to HSA at Sudlow site I. The effect of tested derivatives on metabolic activity of A549 cells evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide or MTT assay decreased as follows 3b(-F) > 3a(-H) > 3c(-Cl) > 3d(-Br). The derivatives 3c and 3d in vitro act as potential dual inhibitors of hTopo I and II with a partial effect on the metabolic activity of cancer cells A594. The acridine-benzohydrazides 3a and 3c reduced the clonogenic ability of A549 cells by 72% or 74%, respectively. The general results of the study suggest that the novel compounds show potential for future development as anticancer agents.

Mesoporous Silica as a Drug Delivery System for Naproxen: Influence of Surface Functionalization.

In this work we describe the relationship between surface modification of hexagonally ordered mesoporous silica SBA-15 and loading/release characteristics of nonsteroidal anti-inflammatory drug (NSAID) naproxen. Mesoporous silica (MPS) was modified with 3-aminopropyl, phenyl and cyclohexyl groups by grafting method. Naproxen was adsorbed into pores of the prepared MPS from ethanol solution using a solvent evaporation method. The release of the drug was performed in buffer medium at pH 2 and physiological solution at pH 7.4. Parent MPSs as well as naproxen loaded MPSs were characterized using physicochemical techniques such as nitrogen adsorption/desorption, thermogravimetric analysis (TG), Zeta potential analysis, Fourier transform infrared spectroscopy (FT-IR), and elemental analysis. The amount of naproxen released from the MPSs into the medium was determined by high-performance liquid chromatography (HPLC). It was shown that the adsorption and desorption characteristics of naproxen are dependent on the pH of the solution and the surface functionalization of the host.

Microporous Lead-Organic Framework for Selective CO2 Adsorption and Heterogeneous Catalysis.

A novel microporous metal-organic framework, {[Pb4(µ8-MTB)2(H2O)4]·5DMF·H2O}n (1; MTB = methanetetrabenzoate and DMF = N,N'-dimethylformamide), was successfully synthesized by a solvothermal reaction and structurally characterized by single-crystal X-ray diffraction. The framework exhibits a unique tetranuclear [Pb4(µ3-COO)(µ2-COO)6(COO)(H2O)4] secondary building unit (SBU). The combination of the SBU with the tetrahedral symmetry of MTB results in a three-dimensional network structure, with one-dimensional jarlike cavities having sizes of about 14.98 × 7.88 and 14.98 × 13.17 Å2 and propagating along the c axis. Due to the presence of four coordinately unsaturated sites per one metal cluster, an activated form of compound 1 (i.e., desolvated form denoted as 1') was tested in gas adsorption and catalytic experiments. The studies of gas sorption revealed that 1' exhibits a surface area (Brunauer-Emmett-Teller) of 980 m2·g-1. This value is the highest reported for any compound from the MTB group. Interactions of carbon dioxide (CO2) molecules with the framework, confirmed by density functional theory calculations, resulted in high CO2 uptake and significant selectivity of CO2 adsorption with respect to methane (CH4) and dinitrogen (N2) when measured from atmospheric pressure to 21 bar. The high selectivity of CO2 over N2 is mostly important for capturing CO2 from the atmosphere in attempts to decrease the greenhouse effect. Moreover, compound 1' was tested as a heterogeneous catalyst in Knoevenagel condensation of active methylene compounds with aldehydes. Excellent catalytic conversion and selectivity in the condensation of benzaldehyde and cyclohexanecarbaldehyde with malononitrile was observed, which suggests that accessible lead(II) sites play an important role in the heterogeneous catalytic process.

A New Member of the Metal-Porphyrin Frameworks Family: Structure, Physicochemical Properties, Hydrogen and Carbon Dioxide Adsorption.

A novel holmium-based porous metal-porphyrin framework, {(H3 O+ )[Ho(H2 TPPS)]- ⋅ 4H2 O}n (denoted as UPJS-17), was synthesised by hydrothermal reaction. Structural analysis reveals, that UPJS-17 has a three-dimensional open framework. The framework is negatively charged and the negative charge is compensated by hydronium cation. The compound showed no N2 adsorption but the Ar, CO2 and H2 . From the argon adsorption, the surface area of ~150 m2 g-1 was determined. Carbon dioxide adsorption was measured at various temperatures (0, 10, 20, 30 and 40 °C) and the compound showed the highest adsorption capacity (at 0 °C) of 7.0 wt % of CO2 . From the carbon dioxide adsorption isotherms the isosteric heat of 56,5 kJ mol-1 was determined. Hydrogen adsorption was studied at -196 °C with hydrogen uptake of 2.1 wt % at 1 bar.

Investigation of polypyrrole based composite material for lithium sulfur batteries.

With the rising demand for electricity storage devices, the performance requirements for such equipment have become increasingly stringent. Lithium-sulfur (Li-S) batteries are poised to be among the next generation of energy storage systems. However, before they can be commercially viable, several challenges must be addressed, including low sulfur conductivity and the shuttle effect. Herein, polypyrrole based sulfur composite was prepared by simple method in hydrothermal teflon lined autoclave for Li-S battery. The S/SP/ppy/PVDF electrode exhibited the initial discharge capacity of 662 mAh g- 1 at 0.5 C and 637 mAh g- 1 after 100 cycles. The Coulombic efficiency was 96% all along charge/discharge cycling. Moreover, Li-S coin cells were assembled and tested to demonstrate the potential application and scale-up of the polypyrrole-sulfur composite.

Synergistic effect of folic acid and hypericin administration to improve the efficacy of photodynamic therapy via folate receptors.

Transport systems are developed to improve the solubility of the transported drug, increase its stability, enhance its pharmacological activity and target cancer while minimising side effects. In this work, nanoporous silica particles that can be functionalized and loaded with a large number of hydrophobic molecules are proposed. The designed system was modified with folic acid to target the folic acid receptors of cancer cells. This modification enabled a higher uptake of the drug by the cells. Hypericin was selected as a hydrophobic molecule/drug with photodynamic properties suitable for diagnosis and therapy. Fluorescence microscopy and flow cytometry were used to detect the targeting and distribution of hypericin in the cancer cells. Furthermore, the combination of folic acid and hypericin has been shown to form singlet oxygen and to have a synergistic effect in improving the efficacy of photodynamic therapy. The functionalisation of the particles proposed in this work holds great potential for the delivery of hydrophobic drugs to other types of cancer cells with increased expression of the folic acid receptor to which the particles can be attached.

The influence of HKUST-1 and MOF-76 hand grinding/mechanical activation on stability, particle size, textural properties and carbon dioxide sorption.

In this study, we explore the mechanical treatment of two metal-organic frameworks (MOFs), HKUST-1 and MOF-76, applying various milling methods to assess their impact on stability, porosity, and CO2 adsorption capacity. The effects of different mechanical grinding techniques, such as high-energy ball milling and hand grinding, on these MOFs were compared. The impact of milling time, milling speed and ball size during high-energy ball milling was assessed via the Design of Experiments methodology, namely using a 33 Taguchi orthogonal array. The results highlight a marked improvement in CO2 adsorption capacity for HKUST-1 through hand milling, increasing from an initial 25.70 wt.% (5.84 mmol g-1) to 41.37 wt.% (9.40 mmol g-1), marking a significant 38% increase. In contrast, high-energy ball milling seems to worsen this property, diminishing the CO2 adsorption abilities of the materials. Notably, MOF-76 shows resistance to hand grinding, closely resembling the original sample's performance. Hand grinding also proved to be well reproducible. These findings clarify the complex effects of mechanical milling on MOF materials, emphasising the necessity of choosing the proper processing techniques to enhance their stability, texture, and performance in CO2 capture and storage applications.

A highly stable terbium(III) metal-organic framework MOF-76(Tb) for hydrogen storage and humidity sensing.

The present study described the synthesis and characterization of MOF-76(Tb) for hydrogen storage and humidity sensing applications. The structure and morphology of as-synthesized material were studied using powder X-ray diffraction, scanning, and transmission electron microscopy. The crystal structure of MOF-76(Tb) consists of terbium(III) and benzene-1,3,5-tricarboxylate(-III) ions, one coordinated aqua ligand and one crystallization N,N´-dimethylformamide molecule. The polymeric framework of MOF-76(Tb) contains 1D sinusoidally shaped channels with sizes of 6.6 × 6.6 Å propagating along c crystallographic axis. The thermogravimetric analysis of the prepared material exhibited thermal stability up to 600 °C. At 77 K and pressure up to 20 bar; 0.6 wt.% hydrogen storage capacity for MOF-76(Tb) was observed. Finally, the humidity sensing measurements (water adsorption experiments) were performed, and the results indicate that MOF-76(Tb) is not a suitable material for moisture sensing applications.

Eco-friendly phytofabrication of Ficus Benjamina L. based ZnO-doped g-C3N4 nanocomposites for remarkable photocatalysis and antibacterial applications.

The research reported here emphasizes the phytoextract route synthesized ZnO-doped g-C3N4 (GCN) for its photocatalytic activity, which helps to ensure a sustained & healthy environment. The leaf extract solution of Ficus Benjamina L. was used for the synthesis of ZnO nanoparticles, and GCN was prepared via urea using a thermal polymerization process. The flower extract functions as both stabilizers and capping agents during the process of synthesis of ZnO nanoparticles. The synthesized nanocomposites were then calcined at 400 °C and were further characterized with spectroscopy (UV-Vis), diffracted pattern (XRD), and infrared spectroscopy (FTIR). Further, the photocatalytic activity of auramine orange (AO) and methylene blue (MB) dye from phytoextract route synthesized pure ZnO NPs, GCN-Pure, and composites with varied millimolar concentrations of ZnO nanoparticles with GCN of the constant amount was checked. After the complete analysis, it was observed that the series that was prepared of ZnO-GCN nanocomposites showed notable enhancement in the degradation pattern of the methylene blue dye. Apparently, 1.5 mmol (mM) ZnO-GCN presented greater degradation patterns for Auramine orange and Methylene blue dye as compared to other nanocomposites that were synthesized. The observed increased photocatalytic activity has a conceivable explanation. The antibacterial activity studies of the prepared nanocomposites were also performed against the E. coli strain showing an enhanced zone of inhibition towards it.

Architecting the Z-scheme heterojunction of Gd2O3/g-C3N4 nanocomposites for enhanced visible-light-induced photoactivity towards organic pollutants degradation.

A basic calcination process in one step was employed to create g-C3N4 photocatalytic composites modified by Gd2O3 nanoparticles. SEM (scanning electron microscopy), FTIR (Fourier-transform infrared spectroscopy), XRD (X-ray diffraction), EIS (electrochemical impedance spectroscopy), PL (photoluminescence studies) as well as TEM (transmission electron microscopy), XPS (X-ray photoelectron spectroscopy), and CV (cyclic voltammetry) were employed to explain the structural traits, optical properties, and morphological features of the processed photocatalyst. The findings show that Gd2O3 (Gd) does not affect the sample's crystalline structure but rather increases g-C3N4 surface area by spreading it superficially. Furthermore, Gd can redshift the light absorption peak, reduce the energy gap, and improve the efficiency with which photogenerated holes and electrons are removed in g-C3N4. The surface morphology of g-C3N4, in particular, could be significantly enhanced. We similarly employed three distinct photocatalytic complexes of Gd2O3 and g-C3N4 in 1:1, 2:1, and 3:1 proportions to degrade methylene blue (MB). After 100 min in visible light (400-800 nm), the photodegradation rate of composites is 58.8% for 1:1 (GG1), 94.5% for 2:1 (GG2), and 92% for 3:1 (GG3). In addition to the MB dye, the photocatalytic activity of synthesized materials was also studied for methyl orange. The result shows phenomenal degradation values, i.e.; for GG1 86%, GG2 96%, and for GG3 84.6%. The narrow band gap that separates the photogenerated electron and hole enhances g-C3N4 ability to degrade photo-catalytically. From the result, we concluded that the photocurrent and cyclic photocatalytic degradation of methylene blue shows that a composition of 2:1 Gd2O3/g-C3N4 has high photocatalytic stability.

Redistribution of hydrophobic hypericin from nanoporous particles of SBA-15 silica in vitro, in cells and in vivo.

Nanoporous silica is nowadays used in various fields of nano- and micro-materials research. The advantage of nanoporous material is that it can be filled with various hydrophilic and hydrophobic molecules, which are then delivered to the target cells and tissues. In the present study, we have studied the interaction of nanoporous silica with hydrophobic and photodynamically active molecule - hypericin. Hypericin was adsorbed on/in SBA-15 silica, which led to the disappearance of its fluorescence due to hypericin aggregate formation. However, it was observed here that hypericin can be easily redistributed from these particles towards proteins and lipids in serum and cells in vitro and in vivo. Moreover, the charged surface character of SBA-15 pores forced the creation of protein/lipid corona on particles. Such complex enabled monomerization of hypericin on the surface of particles presented by fluorescence in the corona and singlet oxygen production suitable for photodynamic therapy (PDT). The PDT efficacy achieved by introducing the new construct into the PDT protocol was comparable to the efficacy of hypericin PDT. In conclusion, this study demonstrates a promising approach for the delivery of hydrophobic photosensitizers to cancer cells by nanoporous silica using fluorescence techniques.

Effective transport of aggregated hypericin encapsulated in SBA-15 nanoporous silica particles for photodynamic therapy of cancer cells.

Photodynamic therapy (PDT) represents an interesting modality for the elimination of damaged biomaterials and cells. This treatment takes advantage of the photosensitizing properties of molecules that are active only when irradiated with light. In the present work, a dual property of hypericin, a hydrophobic molecule with high performance in photodiagnostics and photodynamic therapy, was exploited. The non-fluorescent and photodynamically inactive form of hypericin aggregates was loaded into the nanopores of SBA-15 silica particles. The synthesized particles were characterized by infrared spectroscopy, thermogravimetry, differential thermal analysis, small-angle X-ray scattering and transmission electron microscopy. Hypericin aggregates were confirmed by absorption spectra typical of aggregated hypericin and by its short fluorescence lifetime. Release of hypericin from the particles was observed toward serum proteins, mimicking physiological conditions. Temperature- and time-dependent uptake of hypericin by cancer cells showed gradual release of hypericin from the particles and active cellular transport by endocytosis. A closer examination of SBA-15-hypericin uptake by fluorescence lifetime imaging showed that aggregated hypericin molecules, characterized by a short fluorescence lifetime (∼4 ns), were still present in the SBA-15 particles upon uptake by cells. However, monomerization of hypericin in cancer cells was observed by extending the hypericin fluorescence lifetime by ∼8 ns, preferentially in lipid compartments and the plasma membrane. This suggests a promising prognosis for delayed biological activity of the entire cargo, which was confirmed by effective PDT in vitro. In summary, this work presents an approach for safe, inactive delivery of hypericin that is activated at the target site in cells and tissues.

Sr(II) and Ba(II) Alkaline Earth Metal-Organic Frameworks (AE-MOFs) for Selective Gas Adsorption, Energy Storage, and Environmental Application.

Two new alkaline earth metal-organic frameworks (AE-MOFs) containing Sr(II) (UPJS-15) or Ba(II) (UPJS-16) cations and extended tetrahedral linker (MTA) were synthesized and characterized in detail (UPJS stands for University of Pavol Jozef Safarik). Single-crystal X-ray analysis (SC-XRD) revealed that the materials are isostructural and, in their frameworks, one-dimensional channels are present with the size of ~11 × 10 Å2. The activation process of the compounds was studied by the combination of in situ heating infrared spectroscopy (IR), thermal analysis (TA) and in situ high-energy powder X-ray diffraction (HE-PXRD), which confirmed the stability of compounds after desolvation. The prepared compounds were investigated as adsorbents of different gases (Ar, N2, CO2, and H2). Nitrogen and argon adsorption measurements showed that UPJS-15 has SBET area of 1321 m2 g-1 (Ar) / 1250 m2 g-1 (N2), and UPJS-16 does not adsorb mentioned gases. From the environmental application, the materials were studied as CO2 adsorbents, and both compounds adsorb CO2 with a maximum capacity of 22.4 wt.% @ 0 °C; 14.7 wt.% @ 20 °C and 101 kPa for UPJS-15 and 11.5 wt.% @ 0°C; 8.4 wt.% @ 20 °C and 101 kPa for UPJS-16. According to IAST calculations, UPJS-16 shows high selectivity (50 for CO2/N2 10:90 mixture and 455 for CO2/N2 50:50 mixture) and can be applied as CO2 adsorbent from the atmosphere even at low pressures. The increased affinity of materials for CO2 was also studied by DFT modelling, which revealed that the primary adsorption sites are coordinatively unsaturated sites on metal ions, azo bonds, and phenyl rings within the MTA linker. Regarding energy storage, the materials were studied as hydrogen adsorbents, but the materials showed low H2 adsorption properties: 0.19 wt.% for UPJS-15 and 0.04 wt.% for UPJS-16 @ -196 °C and 101 kPa. The enhanced CO2/H2 selectivity could be used to scavenge carbon dioxide from hydrogen in WGS and DSR reactions. The second method of applying samples in the area of energy storage was the use of UPJS-15 as an additive in a lithium-sulfur battery. Cyclic performance at a cycling rate of 0.2 C showed an initial discharge capacity of 337 mAh g-1, which decreased smoothly to 235 mAh g-1 after 100 charge/discharge cycles.

Carbon dioxide and hydrogen adsorption study on surface-modified HKUST-1 with diamine/triamine.

The present article intended to study the influence of post-synthetic modification with ethylenediamine (en, diamine) and diethylenetriamine (deta, triamine) within the coordinatively unsaturated sites (CUSs) of HKUST-1 on carbon dioxide and hydrogen storage. The as-sythesized adsorbent was solvent-exchanged and subsequently post-synthetically modified with di-/triamines as sources of amine-based sorption sites due to the increased CO2 storage capacity. It is known that carbon dioxide molecules have a high affinity for amine groups, and moreover, the volume of amine molecules itself reduces the free pore volume in HKUST-1, which is the driving force for increasing the hydrogen storage capacity. Different concentrations of amines were used for modification of HKUST-1, through which materials with different molar ratios of HKUST-1 to amine: 1:0.05; 1:0.1; 1:0.25; 1:0.5; 1:0.75; 1:1; 1:1.5 were synthesized. Adsorption measurements of carbon dioxide at 0 °C up to 1 bar have shown that the compounds can adsorb large amounts of carbon dioxide. In general, deta-modified samples showed higher adsorbed amounts of CO2 compared to en-modified materials, which can be explained by the higher number of amine groups within the deta molecule. With an increasing molar ratio of amines, there was a decrease in wt.% CO2. The maximum storage capacity of CO2 was 22.3 wt.% for HKUST-1: en/1:0.1 and 33.1 wt.% for HKUST-1: deta/1:0.05 at 0 °C and 1 bar. Hydrogen adsorption measurements showed the same trend as carbon dioxide, with the maximum H2 adsorbed amounts being 1.82 wt.% for HKUST-1: en/1:0.1 and 2.28 wt.% for HKUST-1: deta/1:0.05 at - 196 °C and 1 bar.

Adsorption and Release Properties of Drug Delivery System Naproxen-SBA-15: Effect of Surface Polarity, Sodium/Acid Drug Form and pH.

Mesoporous silica SBA-15 was prepared via sol-gel synthesis and functionalized with different types of organosilanes containing various organic functional groups: (3-aminopropyl)triethoxysilane (SBA-15-NH2), (3-mercaptopropyl)triethoxysilane (SBA-15-SH), triethoxymethylsilane (SBA-15-CH3), triethoxyphenylsilane (SBA-15-Ph), and (3-isocynatopropyl)triethoxysilane (SBA-15-NCO). The prepared materials were investigated as drug delivery systems for naproxen. As model drugs, naproxen acid (HNAP) and its sodium salt (NaNAP) were used. Mentioned medicaments belong to the group of non-steroidal anti-inflammatory drugs (NSAIDs). The prepared materials were characterized by different analytical methods such as transmission electron microscopy (TEM), infrared spectroscopy (IR), nitrogen adsorption/desorption analysis (N2), thermogravimetric analysis (TG), 1H, 13C and 23Na solid-state nuclear magnetic resonance spectroscopy (1H, 13C and 23Na ss-NMR). The abovementioned analytical techniques confirmed the successful grafting of functional groups to the SBA-15 surface and the adsorption of drugs after the impregnation process. The BET area values decreased from 927 m2 g-1 for SBA-15 to 408 m2 g-1 for SBA-15-NCO. After drug encapsulation, a more significant decrease in surface area was observed due to the filling of pores with drug molecules, while the most significant decrease was observed for the SBA-15-NH2 material (115 m2 g-1 for NaNAP and 101 m2 g-1 for HNAP). By combining TG and nitrogen adsorption results, the occurrence of functional groups and the affinity of drugs to the carriers' surface were calculated. The dominant factor was the volume of functional groups and intermolecular interactions. The highest drug affinity values were observed for phenyl and amine-modified materials (SBA-15-Ph = 1.379 µmol m-2 mmol-1 for NaNAP, 1.761 µmol m-2 mmol-1 for HNAP and SBA-15-NH2 = 1.343 µmol m-2 mmol-1 for NaNAP, 1.302 µmol m-2 mmol-1 for HNAP) due to the formation of hydrogen bonds and π-π interactions, respectively. Drug release properties and kinetic studies were performed at t = 37 °C (normal human body temperature) in different media with pH = 2 as simulated human gastric fluid and pH = 7.4, which simulated a physiological environment. Determination of drug release quantity was performed with UV-VIS spectroscopy. The surface polarity, pH and naproxen form influenced the total released amount of drug. In general, naproxen sodium salt has a higher solubility than its acid form, thus significantly affecting drug release from surface-modified SBA-15 materials. Different pH conditions involved surface protonation and formation/disruption of intermolecular interactions, influencing both the release rate and the total released amount of naproxen. Different kinetic models, zero-order, first-order, Higuchi and Hixson-Crowell models, were used to fit the drug release data. According to the obtained experimental results, the drug release rates and mechanisms were determined.

Post-synthetically modified metal-porphyrin framework GaTCPP for carbon dioxide adsorption and energy storage in Li-S batteries.

Lithium-sulphur batteries attract increasing interest due to their high theoretical specific capacity, advantageous economy, and "eco-friendliness". In this study, a metal-organic framework (MOF) GaTCPP containing a porphyrinic base ligand was used as a conductive additive for sulphur. GaTCPP was synthesized, characterized, and post-synthetically modified by the transition metal ions (Co2+/Ni2+). The doping of GaTCPP ensured an increase in the carbon dioxide adsorption capacities, which were measured under different conditions. Post-synthetic modification of GaTCPP with Co2+/Ni2+ ions has been shown to increase carbon dioxide storage capacity from 22.8 wt% for unmodified material to 23.1 wt% and 26.5 wt% at 0 °C and 1 bar for Co2+ and Ni2+-doped analogues, respectively. As a conductive part of cathode material, MOFs displayed successful sulphur capture and encapsulation proven by stable charge/discharge cycle performances, high-capacity retention, and coulombic efficiency. The electrodes with pristine GaTCPP showed a discharge capacity of 699 mA h g-1 at 0.2C in the fiftieth cycle. However, the doping of GaTCPP by Ni2+ has a positive impact on the electrochemical properties, the capacity increased to 778 mA h g-1 in the fiftieth cycle at 0.2C.

Gd(III) metal-organic framework as an effective humidity sensor and its hydrogen adsorption properties.

Metal-organic frameworks (MOFs) represent a class of nanoporous materials built up by metal ions and organic linkers with several interesting potential applications. The present study described the synthesis and characterization of Gd(III)-based MOF with the chemical composition [Gd(BTC)(H2O)]·DMF (BTC - trimesate, DMF = N,N'-dimethylformamide), known as MOF-76(Gd) for hydrogen adsorption/desorption capacity and humidity sensing applications. The structure and morphology of as-synthesized material were studied using powder X-ray diffraction, scanning and transmission electron microscopy. The crystal structure of MOF-76(Gd) consists of gadolinium (III) and benzene-1,3,5-tricarboxylate ions, one coordinated aqua ligand and one crystallization DMF molecule. The polymeric framework of MOF-76(Gd) contains 1D sinusoidally shaped channels with sizes of 6.7 × 6.7 Å propagating along c crystallographic axis. The thermogravimetric analysis, heating infrared spectroscopy and in-situ heating powder X-ray diffraction experiments of the prepared framework exhibited thermal stability up to 550 °C. Nitrogen adsorption/desorption measurement at -196 °C showed a BET surface area of 605 m2 g-1 and pore volume of 0.24 cm3 g-1. The maximal hydrogen storage capacity of MOF-76(Gd) was 1.66 wt % and 1.34 wt % -196 °C and -186 °C and pressure up to 1 bar, respectively. Finally, the humidity sensing measurements (water adsorption experiments) were performed, and the results indicate that MOF-76(Gd) is a suitable material for moisture sensing application with a fast response (11 s) and recovery time (2 s) in the relative humidity range of 11-98%.

Zinc(ii) and cadmium(ii) amorphous metal-organic frameworks (aMOFs): study of activation process and high-pressure adsorption of greenhouse gases.

Two novel amorphous metal-organic frameworks (aMOFs) with chemical composition {[Zn2(MTA)]·4H2O·3DMF} n (UPJS-13) and {[Cd2(MTA)]·5H2O·4DMF} n (UPJS-14) built from Zn(ii) and Cd(ii) ions and extended tetrahedral tetraazo-tetracarboxylic acid (H4MTA) as a linker were prepared and characterised. Nitrogen adsorption measurements were performed on as-synthesized (AS), ethanol exchanged (EX) and freeze-dried (FD) materials at different activation temperatures of 60, 80, 100, 120, 150 and 200 °C to obtain the best textural properties. The largest surface areas of 830 m2 g-1 for UPJS-13 (FD) and 1057 m2 g-1 for UPJS-14 (FD) were calculated from the nitrogen adsorption isotherms for freeze-dried materials activated at mild activation temperature (80 °C). Subsequently, the prepared compounds were tested as adsorbents of greenhouse gases, carbon dioxide and methane, measured at high pressures. The maximal adsorption capacities were 30.01 wt% CO2 and 4.84 wt% CH4 for UPJS-13 (FD) and 24.56 wt% CO2 and 6.38 wt% CH4 for UPJS-14 (FD) at 20 bar and 30 °C.

Thermosensitive Drug Delivery System SBA-15-PEI for Controlled Release of Nonsteroidal Anti-Inflammatory Drug Diclofenac Sodium Salt: A Comparative Study.

Mesoporous SBA-15 silica material was prepared by the sol-gel method and functionalized with thermosensitive polyethylenimine polymers with different molecular weight (g·mol-1): 800 (SBA-15(C)-800), 1300 (SBA-15(C)-1300) and 2000 (SBA-15(C)-2000). The nonsteroidal anti-inflammatory drug (NSAID) diclofenac sodium was selected as a model drug and encapsulated into the pores of prepared supports. Materials were characterized by the combination of infrared spectroscopy (IR), atomic force microscopy (AFM), transmission electron microscopy (TEM), photon cross-correlation spectroscopy (PCCS), nitrogen adsorption/desorption analysis, thermogravimetry (TG), differential scanning calorimetry (DSC) and small-angle X-ray diffraction (SA-XRD) experiments. The drug release from prepared matrixes was realized in two model media differing in pH, namely small intestine environment/simulated body fluid (pH = 7.4) and simulated gastric fluid (pH = 2), and at different temperatures, namely normal body temperature (T = 37 °C) and inflammatory temperature (T = 42 °C). The process of drug loading into the pores of prepared materials from the diclofenac sodium salt solutions with different concentrations and subsequent quantitative determination of released drugs was analyzed by UV-VIS spectroscopy. Analysis of prepared SBA-15 materials modified with polyethylenimines in solution showed a high ability to store large amounts of the drug, up to 230 wt.%. Experimental results showed their high drug release into the solution at pH = 7.4 for both temperatures, which is related to the high solubility of diclofenac sodium in a slightly alkaline environment. At pH = 2, a difference in drug release rate was observed between both temperatures. Indeed, at a higher temperature, the release rates and the amount of released drug were 2-3 times higher than those observed at a lower temperature. Different kinetic models were used to fit the obtained drug release data to determine the drug release rate and its release mechanism. Moreover, the drug release properties of prepared compounds were compared to a commercially available medicament under the same experimental conditions.