Harnessing bio-based chelating agents for sustainable synthesis of AgNPs: Evaluating their inherent attributes and antimicrobial potency in conjunction with honey.

Greenly synthesized nanoparticles have garnered attention due to their low environmental footprint, but impurities limit their applications. A novel semi-organic method for synthesizing silver nanoparticles (AgNPs) using bio-based chelating fuels (Beta vulgaris subsp., Spinacia oleracea, and Ipomoea batatas) reduces the undesirable impurities. The study also showcases the impact of bio-based chelating fuel on various characteristics of AgNPs in comparison to synthetic chelating fuel. The antimicrobial efficacy of the synthesized AgNPs in conjunction with honey was also assessed against E. coli. The XRD analysis showed cubic structure of AgNPs. The FESEM and TEM analysis showed that the well-connected spherical-shaped AgNPs (∼3-120 nm diameter) while EDS confirmed the presence of Ag in all samples. The TEM analysis also revealed layers of carbonates in AgNPs synthesized using bio-based chelating fuels. XPS investigation confirmed the absence of any prominent impurities in prepared samples and AgNPs have not experienced oxidation on their surface. However, notable surface charging effects due to the uneven conductivity of the particles were observed. The broth dilution method showed that all mixtures containing AgNPs in combination with honey exhibited a significant bacterial growth reduction over a period of 120 h. The highest growth reduction of ∼75 % is obtained for the mixture having AgNPs (Ipomoea batatas) while the least growth reduction of ∼51 % is obtained for the mixture having AgNPs (Beta vulgaris subsp.). The findings affirm that AgNPs can be successfully synthesized using bio-based chelating fuels with negligible ecological consequences and devoid of contaminants. Moreover, the synthesized AgNPs can be employed in conjunction with honey for antibacterial purposes.

Influence of Eu3+ Doping on Physiochemical Properties and Neuroprotective Potential of Polyacrylic Acid Functionalized Cerium Oxide Nanoparticles.

Cerium oxide nanoparticles (CeONPs) exhibiting antioxidant properties are investigated as potential tools for neurodegenerative diseases. Here, we synthesized polyacrylic acid conjugated cerium oxide (CeO) nanoparticles, and further to enhance their neuroprotective effect, Eu3+ was substituted at different concentrations (5, 10, 15 and 20 mol%) to the CeO, which can also impart fluorescence to the system. CeONPs and Eu-CeONPs in the size range of 15-30 nm were stable at room temperature. The X-ray Photoelectron Spectroscopy (XPS) analysis revealed the chemical state of Eu and Ce components, and we could conclude that all Eu3+ detected on the surface is well integrated into the cerium oxide lattice. The emission spectrum of Eu-CeO arising from the 7F0 → 5D1 MD and 7F0 → 5D2 transitions indicated the Eu3+ ion acting as a luminescence center. The fluorescence of Eu-CeONPs was visualized by depositing them at the surface of positively charged latex particles. The developed nanoparticles were safe for human neuronal-like cells. Compared with CeONPs, Eu-CeONPs at all concentrations exhibited enhanced neuroprotection against 6-OHDA, while the protection trend of Eu-CeO was similar to that of CeO against H2O2 in SH-SY5Y cells. Hence, the developed Eu-CeONPs could be further investigated as a potential theranostic probe.

Neuroprotective effects of polyacrylic acid (PAA) conjugated cerium oxide against hydrogen peroxide- and 6-OHDA-induced SH-SY5Y cell damage.

Cerium oxide nanoparticles have been widely investigated against neurodegenerative diseases due to their antioxidant properties that aid in quenching reactive oxygen species. In this study, polyacrylic acid conjugated cerium oxide (PAA-CeO) nanoparticles were synthesized in a 50-60 nm size range with a zeta potential of - 35 mV. X-ray photoelectron spectroscopy analysis revealed a mixed valence state of Ce4+ and Ce3+. PAA-CeO nanoparticles were safe for undifferentiated (UN-) and retinoic acid-differentiated (RA-) human neuroblastoma SH-SY5Y cells and reduced the extent of cell damage evoked by hydrogen peroxide (H2O2) and 6-hydroxydopamine (6-OHDA). In the H2O2 model of cell damage PAA-CeO did not affect the caspase-3 activity (apoptosis marker) but attenuated the number of propidium iodide-positive cells (necrosis marker). In the 6-OHDA model, nanoparticles profoundly reduced necrotic changes and partially attenuated caspase-3 activity. However, we did not observe any impact of PAA-CeO on intracellular ROS formation induced by H2O2. Further, the flow cytometry analysis of fluorescein isothiocyanate-labeled PAA-CeO revealed a time- and concentration-dependent cellular uptake of nanoparticles. The results point to the neuroprotective potential of PAA-CeO nanoparticles against neuronal cell damage induced by H2O2 and 6-OHDA, which are in both models associated with the inhibition of necrotic processes and the model-dependent attenuation of activity of executor apoptotic protease, caspase-3 (6-OHDA model) but not with the direct inhibition of ROS (H2O2 model).

Enzymatic functionalization of liquid phase exfoliated graphene using horseradish peroxidase and laccase.

We present a novel approach for the enzymatic functionalization of graphene, utilizing horseradish peroxidase (HPO) and laccase (LC) from Trametes versicolor. This study demonstrates, for the first time, the covalent modification of non-homogeneous graphene with a low surface-to-volume ratio, both in solution and on solid support. Through thermogravimetry analysis, we estimate the degree of functionalization to be 11% with HPO and 4% with LC, attributed to the varying redox potentials of the enzymes. This work highlights the potential of enzymatic reactions for tailored functionalization of graphene under mild conditions.

Effect of Ionization Degree of Poly(amidoamine) Dendrimer and 5-Fluorouracil on the Efficiency of Complex Formation-A Theoretical and Experimental Approach.

Due to their unique structure, poly(amidoamine) (PAMAM) dendrimers can bind active ingredients in two ways: inside the structure or on their surface. The location of drug molecules significantly impacts the kinetics of active substance release and the mechanism of internalization into the cell. This study focuses on the effect of the protonation degree of the G4PAMAM dendrimer and the anticancer drug 5-fluorouracil (5FU) on the efficiency of complex formation. The most favorable conditions for constructing the G4PAMAM-5FU complex are a low degree of protonation of the dendrimer molecule with the drug simultaneously present in a deprotonated form. The fluorine components in the XPS spectra confirm the formation of the stable complex. Through SAXS and DLS methods, a decrease in the dendrimer's molecular size resulting from protonation changes at alkaline conditions was demonstrated. The gradual closure of the dendrimer structure observed at high pH values makes it difficult for the 5FU molecules to migrate to the interior of the support structure, thereby promoting drug immobilization on the surface. The 1H NMR and DOSY spectra indicate that electrostatic interactions determine the complex formation process. Through MD simulations, the localization profile and the number of 5FU molecules forming the complex were visualized on an atomic scale.

Impact of Cerium Oxide on the State and Hydrogenation Activity of Ruthenium Species Incorporated on Mesocellular Foam Silica.

Herein, the impact of cerium species loaded on mesoporous silica of MCF type on the state and catalytic activity of ruthenium species was studied. Up to 20 wt.% of cerium was incorporated on the silica surface, whereas the same 1 wt.% of Ru loading was applied. The samples prepared were examined by low temperature N2 adsorption/desorption, XRD, XRF, ICP-OES, XPS and H2 chemisorption. The catalytic activity of the materials obtained was investigated in the transformation of levulinic acid to γ-valerolactone. It was documented that the presence of Ce favored an increase in the dispersion of ruthenium species, which had a positive impact on the hydrogenation activity for up to 10 wt.% of Ce. Nevertheless, the highest cerium loading had a negative influence on the textural parameters of the support.

Structural, electrical, and magnetic study of La-, Eu-, and Er- doped bismuth ferrite nanomaterials obtained by solution combustion synthesis.

In this work, the multiferroic bismuth ferrite materials Bi0.9RE0.1FeO3 doped by rare-earth (RE = La, Eu, and Er) elements were obtained by the solution combustion synthesis. Structure, electrical, and magnetic properties of prepared samples were investigated by X-ray photoelectron spectroscopy, Mössbauer spectroscopy, electrical hysteresis measurement, broadband dielectric spectroscopy, and SQUID magnetometry. All obtained nanomaterials are characterized by spontaneous electrical polarization, which confirmed their ferroelectric properties. Investigation of magnetic properties at 300.0 K and 2.0 K showed that all investigated Bi0.9RE0.1FeO3 ferrites possess significantly higher magnetization in comparison to bismuth ferrites obtained by different methods. The highest saturation magnetisation of 5.161 emu/g at 300.0 K was observed for the BLaFO sample, while at 2.0 K it was 12.07 emu/g for the BErFO sample. Several possible reasons for these phenomena were proposed and discussed.

Aluminum Doped Titania as a Support of Copper Catalysts for SCR of Nitrogen Oxides.

Aluminum doped titania samples were synthesized as supports of copper oxide catalysts for NO reduction with ammonia. Samples were prepared by the sol-gel method with various ratios of aluminum to titanium. Their thermal stability was examined by TG/DSC methods which revealed that precursors were decomposed at 450 °C. The XRD measurements showed that aluminum caused the diminishing of titania crystallites and was built into the anatase structure or formed an amorphous phase. The admixture of aluminum in titania resulted in a significant increase in specific surface area of mesoporous supports as determined by low temperature sorption of nitrogen. Results of the catalytic tests over copper/aluminum-titania samples obtained by impregnation pointed out that the addition of aluminum broadened the temperature window of high catalytic activity. The increase in Al concentration shifted the temperature of maximum activity to higher values, and at the same time lowered nitrous oxide formation as well. Better catalytic efficiency could result from high copper dispersion on the catalysts surface, as well as the synergistic interaction between Ti and Cu causing reduction in CuO species as confirmed by XPS measurements. It was shown that copper was present as Cu+ species mainly, forming Cu-O-Ti bonds on the catalysts surface.

Photocatalytic activity of titanium dioxide modified by silver nanoparticles.

Photocatalytic activity of Ag/TiO(2) composites obtained by photoreduction treatment (PRT) was investigated. The composite materials, containing various ratio of silver nanoparticles (0.6-3.7 wt %) were obtained by depositing silver on the Evonic-Degussa P25 titania surface. Selected samples whose color varied between light rose and purple brown were examined by SEM, TEM, XPS, DRS, and BET techniques. Flat band potential was determined using Roy method. TEM analysis showed spherically shaped silver nanoparticles of the diameter 4-12 nm. The XPS measurements revealed that silver particles were obtained mainly in metallic form. DRS spectra and photovoltage measurements showed that silver nanoparticles modified the P25 spectral properties but they changed neither the band gap nor the location of flat band potential. The photocatalytic activity of Ag/P25 composite was compared to the photocatalytic activity of pure P25 in the photooxidation reaction of an important potable water contaminant humic acid (HA) and two model compounds, oxalic acid (OxA) and formic acid (FA). The photodecomposition reaction was investigated in a batch reactor containing aqueous suspension of a photocatalyst illuminated by either UV or artificial sunlight (halogen lamp). The tests proved that a small amount of silver nanoparticles deposited on the titania surface triggers the increase in photocatalytic activity; this increase depends, however, on the decomposed substance.