Phase-Dependent Properties of Manganese Oxides and Applications in Electrovoltaics.

This study reports first-principles predictions as well as experimental synthesis of manganese oxide nanoparticles under different conditions. The theoretical part of the work comprised density functional theory (DFT)-based calculations and first-principles molecular dynamics (MD) simulations. The extensive research efforts and the current challenges in enhancing the performance of the lithium-ion battery (LIB) provided motivation to explore the potential of these materials for use as an anode in the battery. The structural analysis of the synthesized samples carried out using X-ray diffraction (XRD) confirmed the tetragonal structure of Mn3O4 on heating at 450 and 550 °C and the cubic structure of Mn2O3 on heating at 650 °C. The structures are found in the form of nanoparticles at 450 and 550 °C, but at 650 °C, the material appeared in the form of a nanoporous structure. Further, we investigated the electrochemical functionality of Mn2O3 and Mn3O4 as anode materials for utilization in LIBs via MD simulations. Based on the investigations of their electrical, structural, diffusion, and storage behavior, the anodic character of Mn2O3 and Mn3O4 is predicted. The findings indicated that 10 lithium atoms adsorb on Mn2O3, whereas 5 lithium atoms adsorb on Mn3O4 when saturation is taken into account. The storage capacities of Mn2O3 and Mn3O4 are estimated to be 1697 and 585 mAh g-1, respectively. The maximum value of lithium insertion voltage per Li in Mn2O3 is 0.93 and 0.22 V in Mn3O4. Further, the diffusion coefficient values are found as 2.69 × 10-9 and 2.65 × 10-10 m2 s-1 for Mn2O3 and Mn3O4, respectively, at 300 K. The climbing image nudged elastic band method (Cl-NEB) was implemented, which revealed activation energy barriers of Li as 0.30 and 0.75 eV for Mn2O3 and Mn3O4, respectively. The findings of the work revealed high specific capacity, low Li diffusion energy barrier, and low open circuit voltage for the Mn2O3-based anode for use in LIBs.

Advancing Dimethacrylate Dental Composites by Synergy of Pre-Polymerized TEGDMA Co-Filler: A Physio-Mechanical Evaluation.

Dental resin composites (DRCs) have gained immense popularity as filling material in direct dental restorations. They are highly valued for their ability to closely resemble natural teeth and withstand harsh oral conditions. To increase the clinical performance of dental restorations, various fillers are incorporated into DRCs. Herein, the effect of incorporating pre-polymerized triethylene glycol dimethacrylate (P-TEGDMA) as a co-filler in varying proportions (0%, 2.5%, 5%, and 10% by weight) into bisphenol A-glycidyl methacrylate (BisGMA)/TEGDMA/SiO2 resin composite was investigated. The obtained DRCs were examined for morphology, rheological properties, degree of crosslinking (DC), Vickers microhardness (VMH), thermal stability, and flexural strength (FS). The results revealed that SiO2 and P-TEGDMA particles were uniformly dispersed. The introduction of P-TEGDMA particles (2.5 wt.%) into the resin composite had a remarkable effect, leading to a significant reduction (p ≤ 0.05) in complex viscosity, decreasing from 393.84 ± 21.65 Pa.s to 152.84 ± 23.94 Pa.s. As a result, the DC was significantly (p ≤ 0.05) improved from 61.76 ± 3.80% to 68.77 ± 2.31%. In addition, the composite mixture demonstrated a higher storage modulus (G') than loss modulus (G″), indicative of its predominantly elastic nature. Moreover, the thermal stability of the DRCs was improved with the addition of P-TEGDMA particles by increasing the degradation temperature from 410 °C to 440 °C. However, the VMH was negatively affected. The study suggests that P-TEGDMA particles have the potential to be used as co-fillers alongside other inorganic fillers, offering a means to fine-tune the properties of DRCs and optimize their clinical performance.

Antimicrobial Activity of Novel Ni(II) and Zn(II) Complexes with (E)-2-((5-Bromothiazol-2-yl)imino)methyl)phenol Ligand: Synthesis, Characterization and Molecular Docking Studies.

In order to address the challenges associated with antibiotic resistance by bacteria, two new complexes, Ni(II) and Zn(II), have been synthesized using the conventional method based on Schiff base ligand (E)-2-((5-bromothiazol-2-yl) imino) methyl) phenol. The Schiff base ligand (HL) was synthesized using salicylaldehyde and 5-(4-bromophenyl)thiazol-2-amine in both traditional and efficient, ecologically friendly, microwave-assisted procedures. The ligand and its complexes were evaluated by elemental analyses, FTIR spectroscopy, UV-Vis spectroscopy, nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA) and magnetic susceptibility. The ligand and its complexes were tested for antibacterial activity against three Gram-positive bacteria (Staphylococcus aureus ATCC 25923, Methicillin-resistant Staphylococcus aureus ATCC 43300 and Enterococcus faecalis ATCC 29212) and three Gram-negative bacteria (Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922 and Klebsiella pneumoniae ATCC 700603). The findings demonstrate the potent activity of the ligand and its complexes against selective bacteria but the Ni(II) complex with MIC values ranging from 1.95 to 7.81 µg/mL outperformed all other compounds, including the widely used antibiotic Streptomycin. Furthermore, the docking study provided evidence supporting the validity of the antimicrobial results, since the Ni complex showed superior binding affinity against to E. coli NAD synthetase, which had a docking score (-7.61 kcal/mol).

Biofabrication of Mg-doped ZnO nanostructures for hemolysis and antibacterial properties.

The aim of this work was to synthesize 0.02 and 0.06 Mg-doped ZnO nanoparticles (NPs) using the aqueous extract of Plectranthus barbatus leaf. The structural integrity of the hexagonal phase was emphasized by X-ray diffraction analysis. The average crystallite size (D) of 0.02 and 0.06 Mg-doped ZnO NPs was found to be 23.83 and 26.95 nm, respectively. The scanning electron microscope images revealed a surface morphology of irregular nano-shapes of about 83 nm diameter with an elongated one-dimensional structure. The hemolysis activity demonstrated the safe nature of the synthesized materials at low doses. Antibacterial activity against S. aureus and E. coli, which assessed using the disc diffusion method, indicated that the prepared NPs could inhibit S. aureus but not E. coli. These findings suggest that the synthesized NPs could be explored for potential applications in biotechnology and medicine.

Lepidium sativum Seed Extract-Mediated Synthesis of Zinc Oxide Nanoparticles: Structural, Morphological, Optical, Hemolysis, and Antibacterial Studies.

Nanomaterials have unique physicochemical properties compared to their bulk counterparts. Besides, biologically synthesized nanoparticles (NPs) have proven superior to other methods. This work aimed to biosynthesize zinc oxide (ZnO) NPs using an aqueous extract of Lepidium sativum seed. The obtained ZnO NPs were characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared, and ultraviolet-visible spectroscopy. The in vitro antibacterial activity of ZnO NPs against Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria was assessed using the disk diffusion technique. The hemolytic impact was quantified spectrophotometrically. The results indicated a 24.2 nm crystallite size, a hexagonal structure phase, and a 3.48 eV optical bandgap. Antibacterial studies revealed a dose-dependent response with comparable activity to the standard drug (gentamicin) and higher activity against S. aureus than E. coli, e.g., the zone of inhibition at 120 mg/mL was 23 ± 1.25 and 16 ± 1.00 mm, respectively. The hemolysis assay showed no potential harm due to ZnO NPs toward red blood cells if utilized in low doses. As a result, it could be concluded that the reported biogenic method for synthesizing ZnO NPs is promising, resulting in hemocompatible NPs and comparable bactericidal agents.

Mevacor/Poly(vinyl acetate/2-hydroxyethyl methacrylate) as Solid Solution: Preparation, Solubility Enhancement and Drug Delivery.

Mevacor/Poly(vinyl acetate-co-2-hydroxyethyl methacrylate) drug carrier systems (MVR/VAC-HEMA) containing different Mevacor (MVR) contents were prepared in one pot by free radical copolymerization of vinyl acetate with 2-hydroxyethyl methacrylate using an LED lamp light in the presence of camphorquinone as a photoinitiator and Mevacor as a drug filler. The prepared material was characterized by FTIR, 1H NMR, DSC, SEM and XRD methods. Different parameters influencing the efficiency in the Mecvacor-water solubility and the drug delivery of this system, such as the swelling capacity of the carrier, the amount of Mevacor loaded and the pH medium have been widely investigated. The results obtained revealed that the Mevacor particles were uniformly dispersed in their molecular state in the copolymer matrix forming a solid solution; the cell toxicity of the virgin poly(vinyl acetate-co-2-hydroxy ethyl methacrylate) (VAC-HEMA) and MVR/VAC-HEMA drug carrier system exhibited no significant effect on their viability when between 0.25 and 2.00 wt% was loaded in these materials; the average swelling capacity of VAC-HEMA material in water was found to be 45.16 wt%, which was practically unaffected by the pH medium and the solubility of MVR deduced from the release process reached more than 22 and 37 times that of the powder dissolved directly in pH 1 and 7 media, respectively. The in vitro MVR release kinetic study revealed that the MVR/VAC-HEMA system containing 0.5 wt% MVR exhibited the best performance in the short gastrointestinal transit (GITT), while that containing 2.0 wt% is for the long transit as they were able to considerably reduce the minimum release of this drug in the stomach (pH1).

Exploring DSSC Efficiency Enhancement: SQI-F and SQI-Cl Dyes with Iodolyte Electrolytes and CDCA Optimization.

This investigation delves into the potential use of halogen bonding to enhance both the short-circuit current (JSC) and overall efficiency of dye-sensitized solar cells (DSSCs). Specifically, we synthesized two distinct dyes, SQI-F and SQI-Cl, and characterized them using FT-IR, 1HNMR, 13C NMR, and mass spectroscopy. These dyes are based on the concept of incorporating halogen atoms within unsymmetrical squaraine structures with a donor-acceptor-donor (D-A-D) configuration. This strategic design aims to achieve optimal performance within DSSCs. We conducted comprehensive assessments using DSSC devices and integrated these synthesized dyes with iodolyte electrolytes, denoted as Z-50 and Z-100. Further enhancements were achieved through the addition of CDCA. Remarkably, in the absence of CDCA, both SQI-F and SQI-Cl dyes displayed distinct photovoltaic characteristics. However, through sensitization with three equivalents of CDCA, a significant improvement in performance became evident. The peak of performance was reached with the SQI-F dye, sensitized with three equivalents of CDCA, and paired with iodolyte Z-100. This combination yielded an impressive DSSC device efficiency of 6.74%, an open-circuit voltage (VOC) of 0.694 V, and a current density (JSC) of 13.67 mA/cm2. This substantial improvement in performance can primarily be attributed to the presence of a σ-hole, which facilitates a robust interaction between the electrolyte and the dyes anchored on the TiO2 substrate. This interaction optimizes the critical dye regeneration process within the DSSCs, ultimately leading to the observed enhancement in efficiency.

Fabrication of Novel Pre-Polymerized BisGMA/Silica Nanocomposites: Physio-Mechanical Considerations.

Resin composite mimics tooth tissues both in structure and properties, and thus, they can withstand high biting force and the harsh environmental conditions of the mouth. Various inorganic nano- and micro-fillers are commonly used to enhance these composites' properties. In this study, we adopted a novel approach by using pre-polymerized bisphenol A-glycidyl methacrylate (BisGMA) ground particles (XL-BisGMA) as fillers in a BisGMA/triethylene glycol dimethacrylate (TEGDMA) resin system in combination with SiO2 nanoparticles. The BisGMA/TEGDMA/SiO2 mixture was filled with various concentrations of XL-BisGMA (0, 2.5, 5, and 10 wt.%). The XL-BisGMA added composites were evaluated for viscosity, degree of conversion (DC), microhardness, and thermal properties. The results demonstrated that the addition of a lower concentration of XL-BisGMA particles (2.5 wt.%) significantly reduced (p ≤ 0.05) the complex viscosity from 374.6 (Pa·s) to 170.84. (Pa·s). Similarly, DC was also increased significantly (p ≤ 0.05) by the addition of 2.5 wt.% XL-BisGMA, with the pristine composite showing a DC of (62.19 ± 3.2%) increased to (69.10 ± 3.4%). Moreover, the decomposition temperature has been increased from 410 °C for the pristine composite (BT-SB0) to 450 °C for the composite with 10 wt.% of XL-BisGMA (BT-SB10). The microhardness has also been significantly reduced (p ≤ 0.05) from 47.44 HV for the pristine composite (BT-SB0) to 29.91 HV for the composite with 2.5 wt.% of XL-BisGMA (BT-SB2.5). These results suggest that a XL-BisGMA could be used to a certain percentage as a promising filler in combination with inorganic fillers to enhance the DC and flow properties of the corresponding resin-based dental composites.

Multifunctional Zn(II) Coordination Polymer as Highly Selective Fluorescent Sensor and Adsorbent for Dyes.

A new Zn(II)-based coordination polymer (1) comprising the Schiff base ligand obtained by the condensation of 5-aminosalicylic acid and salicylaldehyde has been synthesized. This newly synthesized compound has been characterized by analytical and spectroscopic methods, and finally, by single-crystal X-ray diffraction technique in this study. The X-ray analysis reveals a distorted tetrahedral environment around the central Zn(II) center. This compound has been used as a sensitive and selective fluorescent sensor for acetone and Ag+ cations. The photoluminescence measurements indicate that in the presence of acetone, the emission intensity of 1 displays quenching at room temperature. However, other organic solvents caused meagre changes in the emission intensity of 1. Additionally, the fluorescence intensity of 1 has been examined in the presence of different ketones viz. cyclohexanone, 4-heptanone, and 5-nonanone, to assess the interaction between the C=O group of the ketones and the molecular framework of 1. Moreover, 1 displays a selective recognition of Ag+ in the aqueous medium by an enhancement in its fluorescence intensity, representing its high sensitivity for the detection of Ag+ ions in a water sample. Additionally, 1 displays the selective adsorption of cationic dyes (methylene blue and rhodamine B). Hence, 1 showcases its potential as an excellent luminescent probe to detect acetone, other ketones, and Ag+ with an exceptional selectivity, and displaying a selective adsorption of cationic dye molecules.

Adsorption Kinetics of Methyl Orange from Model Polluted Water onto N-Doped Activated Carbons Prepared from N-Containing Polymers.

This study aimed to assess the role of polymeric sources (polypyrrole, polyaniline, and their copolymer) of nitrogen (N)-doped activated carbons (indexed as PAnAC, PPyAC, and PnyAC, respectively) on their adsorption efficiency to remove methyl orange (MO) as a model cationic dye. The adsorbents were characterized using FTIR, SEM, TGA, elemental analysis, and surface area. The kinetic experiments were performed in batches at different MO concentrations (C0) and adsorbent dosages. The adsorption kinetic profiles of pseudo-first-order, pseudo-second-order (PSO), Elovich, intraparticle diffusion, and liquid film diffusion models were compared. The results showed a better fit to the PSO model, suggesting a chemisorption process. The adsorption capacity (qe, mg/g) was found to have increased as MO C0 increased, yet decreased as the adsorbent quantity increased. At the adsorption operating condition, including MO C0 (200 ppm) and adsorbent dose (40 mg), the calculated qe values were in the order of PAnAC (405 mg/g) > PPyAC (204 mg/g) > PnyAC (182 mg/g). This trend proved the carbon precursor's importance in the final properties of the intended carbons; elemental analysis confirmed that the more nitrogen atoms are in the activated carbon, the greater the number of active sites in the adsorbent for accommodating adsorbates. The diffusion mechanism also assumed a rate-limiting step controlled by the film and intraparticle diffusion. Therefore, such an efficient performance may support the target route's usefulness in converting nitrogenous-species waste into valuable materials.

Antiproliferative Mechanisms of a Polyphenolic Combination of Kaempferol and Fisetin in Triple-Negative Breast Cancer Cells.

Herein, we investigate the combinatorial therapeutic effects of naturally occurring flavonoids kaempferol (K) and fisetin (F) on triple-negative breast cancer (TNBC: MDA-MB-231 cell line). Dose-dependent MTT assay results show that K and F exhibited cytotoxicity in MDA-MB-231 cells at 62 and 75 µM (IC50), respectively, after 24 h. However, combined K + F led to 40% and more than 50% TNBC cell death observed at 10 and 20 µM, respectively, which revealed the synergistic association of both. The combination of K and F was determined to be more effective in inhibiting cell viability than either of the agents alone. The morphological changes associated with significant apoptotic cell death were observed under a fluorescent microscope, strongly supporting the synergistic association between K and F. We also proposed that combining the effects of both polyphenols, as opposed to their individual effects, would increase their in vitro efficacy. Furthermore, we assessed the cell death pathway by the combinational treatment via reactive oxygen species-induced DNA damage and the mitochondrially mediated apoptotic pathway. This study reveals the prominent synergistic role of phytochemicals, which helps in elevating the therapeutic efficacy of dietary nutrients and that anticancer effects may be a result of nutrients that act in concert.

Investigation of Newly Synthesized Bis-Acyl-Thiourea Derivatives of 4-Nitrobenzene-1,2-Diamine for Their DNA Binding, Urease Inhibition, and Anti-Brain-Tumor Activities.

Bis-acyl-thiourea derivatives, namely N,N'-(((4-nitro-1,2-phenylene)bis(azanediyl)) bis(carbonothioyl))bis(2,4-dichlorobenzamide) (UP-1), N,N'-(((4-nitro-1,2-phenylene) bis(azanediyl))bis(carbonothioyl))diheptanamide (UP-2), and N,N'-(((4-nitro-1,2-phenylene)bis(azanediyl))bis(carbonothioyl))dibutannamide (UP-3), were synthesized in two steps. The structural characterization of the derivatives was carried out by FTIR, 1H-NMR, and 13C-NMR, and then their DNA binding, anti-urease, and anticancer activities were explored. Both theoretical and experimental results, as obtained by density functional theory, molecular docking, UV-visible spectroscopy, fluorescence (Flu-)spectroscopy, cyclic voltammetry (CV), and viscometry, pointed towards compounds' interactions with DNA. However, the values of binding constant (Kb), binding site size (n), and negative Gibbs free energy change (ΔG) (as evaluated by docking, UV-vis, Flu-, and CV) indicated that all the derivatives exhibited binding interactions with the DNA in the order UP-3 > UP-2 > UP-1. The experimental findings from spectral and electrochemical analysis complemented each other and supported the theoretical analysis. The lower diffusion coefficient (Do) values, as obtained from CV responses of each compound after DNA addition at various scan rates, further confirmed the formation of a bulky compound-DNA complex that caused slow diffusion. The mixed binding mode of interaction as seen in docking was further verified by changes in DNA viscosity with varying compound concentrations. All compounds showed strong anti-urease activity, whereas UP-1 was found to have comparatively better inhibitory efficiency, with an IC50 value of 1.55 ± 0.0288 µM. The dose-dependent cytotoxicity of the synthesized derivatives against glioblastoma MG-U87 cells (a human brain cancer cell line) followed by HEK-293 cells (a normal human embryonic kidney cell line) indicated that UP-1 and UP-3 have greater cytotoxicity against both cancerous and healthy cell lines at 400 µM. However, dose-dependent responses of UP-2 showed cytotoxicity against cancerous cells, while it showed no cytotoxicity on the healthy cell line at a low concentration range of 40-120 µM.

Novel 1,2-Bismethacrylate-3-Eugenyl Propane for Resin Composites: Synthesis, Characterization, Rheological, and Degree of Conversion.

This work aimed to synthesize a novel dimethacrylated-derivative of eugenol (Eg) (termed EgGAA) as potential biomaterial for certain applications such as dental fillings and adhesives. EgGAA was synthesized through a two-step reaction: (i) a mono methacrylated-eugenol (EgGMA) was produced via a ring-opening etherification of glycidyl methacrylate (GMA) with Eg; (ii) EgGMA was condensed with methacryloyl chloride into EgGAA. EgGAA was further incorporated in matrices containing BisGMA and TEGDMA (50:50 wt%) (TBEa), in which EgGAA replaced BisGMA as 0-100 wt% to get a series of unfilled resin composites (TBEa0-TBEa100), and by addition of reinforcing silica (66 wt%), a series of filled resins were also obtained (F-TBEa0-F-TBEa100). Synthesized monomers were analyzed for their structural, spectral, and thermal properties using FTIR, 1H- and 13C-NMR, mass spectrometry, TGA, and DSC. Composites rheological and DC were analyzed. The viscosity (η, Pa·s) of EgGAA (0.379) was 1533 times lower than BisGMA (581.0) and 125 times higher than TEGDMA (0.003). Rheology of unfilled resins (TBEa) indicated Newtonian fluids, with viscosity decreased from 0.164 Pa·s (TBEa0) to 0.010 Pa·s (TBEa100) when EgGAA totally replaced BisGMA. However, composites showed non-Newtonian and shear-thinning behavior, with complex viscosity (η*) being shear-independent at high angular frequencies (10-100 rad/s). The loss factor crossover points were at 45.6, 20.3, 20.4, and 25.6 rad/s, indicating a higher elastic portion for EgGAA-free composite. The DC was insignificantly decreased from 61.22% for the control to 59.85% and 59.50% for F-TBEa25 and F-TBEa50, respectively, while the difference became significant when EgGAA totally replaced BisGMA (F-TBEa100, DC = 52.54%). Accordingly, these properties could encourage further investigation of Eg-containing resin-based composite as filling materials in terms of their physicochemical, mechanical, and biological potentiality as dental material.

Quantum Computational, Spectroscopic (FT-IR, FT-Raman, NMR, and UV-Vis) Hirshfeld Surface and Molecular Docking-Dynamics Studies on 5-Hydroxymethyluracil (Monomer and Trimer).

For many decades, uracil has been an antineoplastic agent used in combination with tegafur to treat various human cancers, including breast, prostate, and liver cancer. Therefore, it is necessary to explore the molecular features of uracil and its derivatives. Herein, the molecule's 5-hydroxymethyluracil has been thoroughly characterized by NMR, UV-Vis, and FT-IR spectroscopy by means of experimental and theoretical analysis. Density functional theory (DFT) using the B3LYP method at 6-311++G(d,p) was computed to achieve the optimized geometric parameters of the molecule in the ground state. For further investigation and computation of the NLO, NBO, NHO analysis, and FMO, the improved geometrical parameters were utilized. The potential energy distribution was used to allocate the vibrational frequencies using the VEDA 4 program. The NBO study determined the relationship between the donor and acceptor. The molecule's charge distribution and reactive regions were highlighted using the MEP and Fukui functions. Maps of the hole and electron density distribution in the excited state were generated using the TD-DFT method and PCM solvent model in order to reveal electronic characteristics. The energies and diagrams for the lowest unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO) were also provided. The HOMO-LUMO band gap estimated the charge transport within the molecule. When examining the intermolecular interactions in 5-HMU, Hirshfeld surface analysis was used, and fingerprint plots were also produced. The molecular docking investigation involved docking 5-HMU with six different protein receptors. Molecular dynamic simulation has given a better idea of the binding of the ligand with protein.

Influence of Eugenol and Its Novel Methacrylated Derivative on the Polymerization Degree of Resin-Based Composites.

The aim of this work was to assess the limiting rate of eugenol (Eg) and eugenyl-glycidyl methacrylate (EgGMA) at which the ideal degree of conversion (DC) of resin composites is achieved. For this, two series of experimental composites, containing, besides reinforcing silica and a photo-initiator system, either EgGMA or Eg molecules at 0-6.8 wt% per resin matrix, principally consisting of urethane dimethacrylate (50 wt% per composite), were prepared and denoted as UGx and UEx, where x refers to the EgGMA or Eg wt% in the composite, respectively. Disc-shaped specimens (5 × 1 mm) were fabricated, photocured for 60 s, and analyzed for their Fourier transform infrared spectra before and after curing. The results revealed concentration-dependent DC, increased from 56.70% (control; UG0 = UE0) to 63.87% and 65.06% for UG3.4 and UE0.4, respectively, then dramatically decreased with the concentration increase. The insufficiency in DC due to EgGMA and Eg incorporation, i.e., DC below the suggested clinical limit (>55%), was observed beyond UG3.4 and UE0.8. The mechanism behind such inhibition is still not fully determined; however, radicals generated by Eg may drive its free radical polymerization inhibitory activity, while the steric hindrance and reactivity of EgGMA express its traced effect at high percentages. Therefore, while Eg is a severe inhibitor for radical polymerization, EgGMA is safer and can be used to benefit resin-based composites when used at a low percentage per resin.

Preparation and Characterization of Poly(vinyl acetate-co-2-hydroxyethyl methacrylate) and In Vitro Application as Contact Lens for Acyclovir Delivery.

A series of poly(vinyl acetate-co-2-hydroxyethylmethacrylate)/acyclovir drug carrier systems (HEMAVAC) containing different acyclovir contents was prepared through bulk free radical polymerization of 2-hydroxyethyl methacrylate with vinyl acetate (VAc) in presence of acyclovir (ACVR) as the drug using a LED lamp in presence of camphorquinone as the photoinitiator. The structure of the drug carrier system was confirmed by FTIR and 1HNMR analysis, and the uniform dispersion of the drug particles in the carrier was proved by DSC and XRD analysis. The study of the physico-chemical properties of the prepared materials, such as the transparency, swelling capacity, wettability and optical refraction, was carried out by UV-visible analysis, a swelling test and measurement of the contact angle and the refractive index, respectively. The elastic modulus and the yield strength of the wet prepared materials were examined by dynamic mechanical analysis. The cytotoxicity of the prepared materials and cell adhesion on these systems were studied by LDH assay and the MTT test, respectively. The results obtained were comparable to those of standard lenses with a transparency of 76.90-89.51%, a swelling capacity of 42.23-81.80% by weight, a wettability of 75.95-89.04°, a refractive index of 1.4301-1.4526 and a modulus of elasticity of 0.67-1.50 MPa, depending on the ACVR content. It was also shown that these materials exhibit no significant cytotoxicity; on the other hand, they show significant cell adhesion. The in vitro dynamic release of ACVR in water revealed that the HEMAVAC drug carrier can consistently deliver uniformly adequate amounts of ACVR (5.04-36 wt%) over a long period (7 days) in two steps. It was also found that the solubility of ACVR obtained from the release process was improved by 1.4 times that obtained by direct solubility of the drug in powder form at the same temperature.

Nitrogen-Rich Polyaniline-Based Activated Carbon for Water Treatment: Adsorption Kinetics of Anionic Dye Methyl Orange.

In the present work, a nitrogen-rich activated carbon (PAnAC) was prepared using polyaniline (PAn) as a precursor to represent one possible conversion of nitrogen-containing polymeric waste into a valuable adsorbent. PAnAC was fabricated under the chemical activation of KOH and a PAn precursor (in a 4:1 ratio) at 650 °C and was characterized using FTIR, SEM, BET, TGA, and CHN elemental composition. The structural characteristics support its applicability as an adsorbent material. The adsorption performance was assessed in terms of adsorption kinetics for contact time (0-180 min), methyl orange (MO) concentration (C0 = 50, 100, and 200 ppm), and adsorbent dosages (20, 40, and 80 mg per 250 mL batch). The kinetic results revealed a better fit to a pseudo-second-order, specifically nonlinear equation compared to pseudo-first-order and Elovich equations, which suggests multilayer coverage and a chemical sorption process. The adsorption capacity (qe) was optimal (405.6 mg/g) at MO C0 with PAnAC dosages of 200 ppm and 40 mg and increased as MO C0 increased but decreased as the adsorbent dosage increased. The adsorption mechanism assumes that chemisorption and the rate-controlling step are governed by mass transfer and intraparticle diffusion processes.

New Method Based on the Direct Analysis in Real Time Coupled with Time-of-Flight Mass Spectrometry to Investigate the Thermal Depolymerization of Poly(methyl methacrylate).

In this work, the isothermal decomposition of poly(methyl methacrylate) synthesized in bulk by the radical route of methyl methacrylate in the presence of azobisisobutyronitrile as the initiator was carried out and monitored for the first time with the DART-Tof-MS technique at different temperatures. Nuclear magnetic resonance (NMR) analysis revealed a predominantly atactic microstructure, and size-exclusion chromatography (SEC) analysis indicated a number average molecular weight of 3 × 105 g·mol-1 and a polydispersity index of 2.47 for this polymer. Non-isothermal decomposition of this polymer carried out with thermogravimetry analysis (TGA) showed that the weight loss process occurs in two steps. The first one starts at approximately 224 °C and the second at 320 °C. The isothermal decomposition of this polymer carried out and monitored with the DART-Tof-MS method revealed only one stage of weight loss in this process, which begins at approximately 250 °C, not far from that of the second step observed in the case of the non-isothermal process conducted with the TGA method. The results obtained with the MS part of this technique revealed that the isothermal decomposition of this polymer regenerates a significant part of methyl methacrylate monomer, which increases with temperature. This process involves radical chain reactions leading to homolytic chain scissions and leading to the formation of secondary and tertiary alkyl radicals, mainly regenerating methyl methacrylate monomer through an unzipping rearrangement. Although they are in the minority, other fragments, such as the isomers of 2-methyl carboxyl, 4-methyl, penta-2,4-diene and dimethyl carbate, are also among the products detected. At 200 °C, no trace of monomer was observed, which coincides with the first step of the weight loss observed in the TGA. These compounds are different to those reported by other researchers using TGA coupled with mass spectrometry in which methyl isobutyrate, traces of methyl pyruvate and 2,3-butanonedione were detected.

Influence of the Physical Inclusion of ZrO2/TiO2 Nanoparticles on Physical, Mechanical, and Morphological Characteristics of PMMA-Based Interim Restorative Material.

Polymethyl methacrylate (PMMA) is often used in restorative dentistry for its easy fabrication, aesthetics, and low cost for interim restorations. However, poor mechanical properties to withstand complex masticatory forces are a concern for clinicians. Therefore, this study aimed to modify a commercially available PMMA-based temporary restorative material by adding TiO2 and ZrO2 nanoparticles in different percentages as fillers and to investigate its physio-mechanical properties. Different percentages (0, 0.5, 1.5, and 3.0 wt%) of TiO2 and ZrO2 nanoparticles were mixed with the pristine PMMA resin (powder to liquid ratio: 1 : 1) and homogenized using high-speed mixer. The composites obtained were analyzed for their flexural strength (F.S.), elastic modulus (E.M.), Vickers hardness (H.V.), surface roughness Ra, morphology and water contact angle (WCA). The mean average was determined with standard deviation (SD) to analyze the results, and a basic comparison test was conducted. The results inferred that adding a small amount (0.5 wt%) of TiO2 and ZrO2 nanoparticles (NPs) could significantly enhance the physio-mechanical and morphological characteristics of PMMA interim restorations. EM and surface hardness increased with increasing filler content, with 3.0 wt.% ZrO2 exhibiting the highest EM (3851.28 MPa), followed by 3.0 wt.% TiO2 (3632.34 MPa). The WCA was significantly reduced from 91.32 ± 4.21° (control) to 66.30 ± 4.23° for 3.0 wt.% ZrO2 and 69.88 ± 3.55° for 3.0 wt.% TiO2. Therefore, TiO2 and ZrO2 NPs could potentially be used as fillers to improve the performance of PMMA and similar interim restorations.

Poly(ethylene-Co-vinyl Alcohol)/Titanium Dioxide Nanocomposite: Preparation and Characterization of Properties for Potential Use in Bone Tissue Engineering.

A series of poly(ethylene-co-vinyl alcohol)/titanium dioxide (PEVAL/TiO2) nanocomposites containing 1, 2, 3, 4 and 5 wt% TiO2 were prepared by the solvent casting method. These prepared hybrid materials were characterized by Fourier-transform infrared (FT-IR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The pores and their interconnections inside these nanocomposites were created using naphthalene microparticles used as a porogen after having been extracted by sublimation under a high vacuum at temperatures slightly below the glass transition temperature. A cellular activity test of these hybrid materials was performed on human gingival fibroblast cells (HGFs) in accordance with ISO 10993-5 and ISO 10993-12 standards. The bioviability (cell viability) of HGFs was evaluated after 1, 4 and 7 days using Alamar Blue®. The results were increased cell activity throughout the different culture times and a significant increase in cell activity in all samples from Day 1 to Day 7, and all systems tested showed significantly higher cell viability than the control group on Day 7 (p < 0.002). The adhesion of HGFs to the scaffolds studied by SEM showed that HGFs were successfully cultured on all types of scaffolds.