Visible Spectrophotometry Research Articles

Study of 14-Substituted-14H-Dibenzo[a,j] Xanthene Derivatives

Xanthene derivatives of the 14-aryl-14H dibenzo[a.j] xanthene type were exploited in our study because of their interesting biological profile as well as their innumerable applications described in previous studies. They were synthesized by one-pot condensation of [Formula: see text]-naphthol with arylaldehydes and catalyzed by zinc trifluoromethanesulfate Zn(OTf)2 under conventional heating without solvent. Their characterization was carried out by Ultraviolet–Visible spectrophotometry (UV–Vis), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). First, spectral analysis in the UV–Vis range showed that all xanthene derivatives had similar absorption spectra at an absorption maximum [Formula: see text] in the region of 310–340[Formula: see text]nm. Similarly, the infrared spectra suggested the presence of characteristic bands for each product in the range of 500–3500[Formula: see text]cm[Formula: see text]. In addition, the analysis of their crystalline structures was carried out by the XRD technique and reported in our study. Finally, their sizes and morphologies were highlighted by SEM. The obtained results revealed the presence of microcrystals in the form of micro-cubes having an average length of 10[Formula: see text][Formula: see text]m for the compound C[Formula: see text]H[Formula: see text]O and micro-shuttles of average size of 20[Formula: see text][Formula: see text]m for the compound C[Formula: see text]H[Formula: see text]BrO. It was therefore concluded that the xanthene derivatives synthesized have characteristic functional groups and structures which will provide them with various therapeutic properties and can therefore be exploited as bioactive molecules in several fields.

Photocatalytic, antibacterial and optoelectronic applications of Terbium doped Zinc oxide nanoparticles prepared via chemical co-precipitation method

This work demonstrates facile synthesis of Tb-doped ZnO nanoparticles and investigates their structural, optical, electrochemical, photocatalytic, and antibacterial performance. XRD patterns of undoped and doped ZnO nanoparticles confirm a hexagonal wurtzite structure. TEM and SAED reveals that the particle size is 14–38 nm. SEM images show that ZnO and Tb-doped ZnO nanoparticles have smooth surfaces, and elemental composition was confirmed by EDX analysis. UV–Visible spectrophotometry studies, reveals that the band gap narrows with increasing Tb concentration. Photoluminescence spectra at room temperature showed a band at 538 nm, indicating zinc vacancies and green emission. Tb-doped ZnO with x = 0.075 exhibited the highest photocatalytic activity for degrading Rose Bengal dye compared to other photocatalysts. The electrochemical behaviour of Catechol (CC), Hydroquinone (HQ), and Bisphenol-A (BPA) at Tb–ZnO/MCPE was studied. The modified electrode process for CC and BPA was adsorption-controlled, and simultaneous recognition of CC, HQ, and BPA was achieved, showing an increase in current. Electro polymerization of poly (Congo red) on Tb–ZnO/MCPE confirmed clean deposition on the surface, enhancing electrocatalytic activity. The antibacterial efficacy was tested using the traditional disc diffusion method, showing effective inactivation of bacterial strains, including pathogens such as S. aureus (G+) and E. coli (G-).

Synergistic photocatalytic performance of MoO3:Cu/g-C3N4 heterojunction semiconductor for efficient crystal violet dye degradation: A sustainable approach for environmental remediation

A heterojunction semiconductor of MoO3:Cu in conjunction with g-C3N4 was fabricated using a green synthesis approach facilitated by leaves extract of Murraya paniculata. Numerous methods of characterisation, including XPS, FTIR spectroscopy, XRD, BET, HR-TEM, FE-SEM, EDAX, and UV–visible spectrophotometry were employed to analyse the materials. The results from XRD and HRTEM indicated the highly crystalline nanoparticles with a mean particle size of 5.42 nm for MoO3 nanomaterials with doping of 5.62 nm Cu particles. The two-dimensional g-C3N4 sheeted structure acted as a translucent layer, facilitating self-assembly on the spherical MoO3:Cu nanoparticles, thereby promoting efficient charge flow and enhancing the photodegradation capability of the heterojunction semiconductor. XPS analysis confirmed the presence of Mo, Cu, N, O, and C in the fabricated heterojunction. UV–Visible and PL spectra demonstrated the efficient suppression of exciton annihilation in the heterojunction semiconductor. Remarkably, the heterojunction exhibited a high photocatalytic degradation performance of 97 % for the photodegradation of Crystal violet (CV) dye. Additionally, the effects of pH and dose of catalyst on photodegradation, as well as the recyclability of the catalyst, were evaluated. Kinetic analysis revealed a pseudo first-order reaction with 0.617 min−1 rate constant, while scavenger experiments confirmed the involvement of h+ and .O2− as active species in the degradation process.

Synthesis of carbon nanotube–iron oxide and silver nanocomposites as photocatalyst in removing carcinogenic aromatic dyes

Abstract In this research, a three-component composite was synthesized by using carbon nanotube as the background phase. Iron oxide phase with high magnetization and low coercivity (with particle size of 200 nm) has been coated on the carbon nanotubes. Then, the silver nanoparticles were coated on a conductive and magnetized substrate by an ultrasonic method. Semiconductor photocatalys is a favorable route for the degradation of organic pollutants. Ultraviolet–visible spectrophotometry has been used to investigate the photocatalytic properties of synthesized nanocomposite and control of their dye degradation on methyl blue, methyl orange and methyl red. The obtained nanocomposite is easily collected due to its magnetic property and does not pose a risk to environmental waters. The dye degradation degree has been compared for the produced nanocomposite. The experimental results confirmed that methyl red shows the greatest amount of degradation within 1 h, which was about 90 %, methyl orange shows about 80 %, and methyl blue shows the lowest degradation, around 60 %.

Adroit effect of copper nanoparticles and copper nanozyme and their effective decolorization of azo dyes

Copper nanoparticles (CuNPs) have garnered considerable attention owed to their straightforward and cost-effective synthesis techniques, making them suitable for various applications across several fields. This paper describes a straightforward method for synthesizing CuNPs using the aqueous chemical reduction approach. A unique copper nanozyme (CNZ) is also prepared to degrade dyes. The nanoparticles were analyzed using various techniques to examine their morphological structure, optical properties, functional groups, and crystallite size via SEM, UV–visible spectrophotometry, FTIR, XRD, and zeta potential with particle size analyzer. SEM analysis showed that the CuNPs have a cubical form, with particle size fluctuating from 250 to 300 nm. The CNZ has a flower-like structure with a typical 100 to 150 nm size. The zeta potential of CuNPs is measured to be + 23.4 mV, indicating a high level of stability for the nanoparticles. The XRD evaluation showed that the CuNPs displayed a prominent peak at an angle of 36.64°, indicating a crystallite size of 26.97 nm. The CNZ displayed a peak at 31.18 nm, corresponding to a crystallite size of 44.84 nm. The capacity of CuNPs and CNZ to degrade a combination of dyes (Methyl orange, Methyl red, Congo red, Tropaeolin-O, and Tartrazine) was investigated. The innovative approach utilizing CNZ and CuNPs resulted in a degradation percentage of 84.61 % for mixed colors. Experimental findings have demonstrated that the combined effect of CuNPs and CNZ is remarkably effective in catalytically degrading azo dyes, making it a highly efficient method for treating effluents from the textile sector and wastewater treatment.

Bioconversion of Alternative Substrates for the Biosynthesis of HMG-CoA Reductase Inhibitors by Aspergillus spp. Strains with Antimicrobial Potential

Simvastatin, a semisynthetic drug widely used to lower cholesterol, is among the most prescribed statins worldwide. This study focuses on the direct production of a simvastatin-like biomolecule using alternative substrates by Aspergillus spp. strains. Two species, A. terreus UCP 1276 and A. flavus UCP 0316, were initially evaluated in synthetic media as control. Subsequently, the carbon and nitrogen sources were replaced by agro-industrial substrates, resulting in five modified media. Cultures were maintained at 28 °C, pH 6.5, at 180 rpm for 21 days. Fungal growth kinetics were evaluated and a 23 full-factorial design (FFD) was used to investigate the influence of substrate concentration on statin yield. Presence of inhibitors was confirmed by bioassay, UV–visible spectrophotometry, and thin-layer chromatography (TLC). According to the results, A. flavus UCP yielded 0.24 mg/g of statin in condition 2 of FFD (medium containing 4.5% soluble starch and saline base), suggesting it as a promising candidate for direct production of the biomolecule. Statistical analysis showed the significant effect of soluble starch on inhibitor production, making it a viable and profitable alternative substrate. Moreover, the isolated statin exhibited broad-spectrum antimicrobial activity, including efficacy against Gram-negative and Gram-positive bacteria and yeasts, indicating therapeutic potential against antimicrobial resistance.

Polyethyleneimine capped silver nanoclusters based turn-off-on fluorescence sensor for the determination of glutathione

A polyethyleneimine capped silver nanoclusters (PEI-AgNCs) based turn-off-on fluorescence sensor has been developed to determine glutathione (GSH) effectively. The fluorescence intensity of silver nanoclusters (AgNCs) has been quenched by Cu(II) and recovered by adding GSH. The quenching of fluorescence intensity of PEI-AgNCs by Cu(II) and recovery of the emission intensity of PEI-AgNCs after the addition of GSH is supposed to be ground state adduct formation. Due to the greater affinity of Cu(II) towards GSH compared to that to PEI-AgNCs, the defragmentation of PEI-AgNCs-Cu(II) adduct occurs after the addition of GSH to the solution, resulting in the recovery of emission intensity of PEI-AgNCs. Characterisation studies of the probe have been done using FT-IR spectroscopy, XPS analysis, XRD analysis, UV–visible and Fluorescence spectrophotometry, EDX spectroscopy and TEM analysis. Different experimental parameters were optimised. Under optimised analytical conditions, the sensor showed a wide linear range for the quantification of GSH from 1.00 × 10−4 M to 3.00 × 10−6 M with a detection limit (LOD) of 8.00 × 10−7 M. Selectivity and interference studies were done in the presence of different structurally similar and coexisting species of GSH in blood. The practical utility of the proposed sensor has been validated in artificial blood serum.

Capsule controlled release of crystallisation inhibitors in mortars

Crystallisation inhibitors, such as sodium ferrocyanide (NaFeCN), are highly effective in mitigating NaCl-induced weathering in lime-based mortars; however, direct addition of NaFeCN in lime-mortars increases its susceptibility to leaching and rapid depletion, thus compromising long-term performance. Here, we present hydrogel-capsules for the controlled-release of NaFeCN within hydraulic mortars for the prolonged prevention of salt weathering. Capsules were prepared by complexing chitosan and calcium-alginate in different ratios containing different concentrations of NaFeCN. The release of NaFeCN from these capsules was measured in (1) simulated lime-mortar solution (2) from mortar specimens incorporated with calcium alginate (CA) and chitosan-calcium-alginate (Cs-CA) capsules using ultraviolet–visible light spectrophotometry and Inductive Coupled Plasma-Optical Emission Spectroscopy. Mortars containing Cs-CA capsules exhibited controlled-release of NaFeCN with four times lower effective diffusion coefficient, compared to incorporating NaFeCN directly in mortar. Conversely, mortar containing CA capsules (without chitosan) released NaFeCN rapidly. Thus, chitosan’s presence in CA is necessary for tuning NaFeCN release and the reason may be attributed to chitosan’s role in reducing CA’s permeability and chitosan’s electrostatic-attraction to ferrocyanide anions, slowing diffusion of the latter. In conclusion, using Cs-CA capsules can control the release of NaFeCN within mortar, providing a steady NaFeCN supply to prolong mortar’s resistance against salt damage.

Harnessing photocatalytic activity of mesoporous graphitic carbon nitride decorated by copper single-atom catalysts for oxidative dehydrogenation of N-heterocycles

This work describes the application of Cu single-atom catalysts (SACs) for photocatalytic oxidative dehydrogenation of N-heterocyclic amines to the respective N-heteroaromatics through environmentally benign and sustainable pathways. The mesoporous graphitic carbon nitride (mpg-C3N4), prepared by the one-step pyrolysis method, possesses a lightweight material with a high surface area (95 m2 g−1) and an average pore diameter (3.6 nm). A simple microwave-assisted preparation method was employed to decorate Cu single-atom over mpg-C3N4 support. The Cu single-atom decorated on mpg-C3N4 support (Cu@mpg-C3N4) is characterized by various characterization techniques, including XRD, UV–visible spectrophotometry, HRTEM, HAADF-STEM with elemental mapping, AC-STEM, ICP-OES, XANES, EXAFS, and BET surface area. These characterization studies confirmed that the Cu@mpg-C3N4 catalyst exhibited high surface area, mesoporous nature, medium band gap, and low metal loading. The as-synthesized and well-characterized Cu@mpg-C3N4 single-atom photocatalyst is then evaluated for its efficacy in converting N-heterocycles into corresponding N-heteroaromatic compounds with excellent conversion and selectivity (>99 %). This transformation is achieved using water as a green solvent and a 30 W white light as a visible light source, demonstrating the catalyst's potential for sustainable and environmentally benign reactions.

Chemical bath assisted construction of CuO/BiVO4 p-n heterojunction photocatalyst for visible light driven rapid removal of MB and Cr(VI)

Nowadays, uncontrolled discharge of industrial wastes containing organic dyes, drugs, as well as heavy metals into the water bodies presents serious pollution of thereby posing threat to the environment. Hence, there is a need to adopt a targeted approach to tackle the matter of water pollution. A method photocatalytic elimination of pollutants using semiconducting materials is a captivating approach. In this study, we report simple chemical bath assisted synthesis of CuO/BiVO4 (CuBi) p-n heterojunction photocatalyst for effective photocatalytic degradation of pollutants. Physico-chemical characteristics of the CuBi composite and its individual counterparts were assessed by XRD, SEM, TEM, BET, XPS and UV–visible spectrophotometry. The CuO mico-planks, BiVO4 nanodots and CuBi composite were utilized for the photocatalytic breakdown of MB dye and Cr(VI) reduction. The CuBi p-n heterojunction demonstrated superior efficiency in degrading MB (99 % within 120 minutes) and reducing Cr (VI) (94 % within 45 minutes) when compared with its bare counterparts. Furthermore, repeating recycle studies for MB degradation and Cr(VI) reduction showed minimal loss in performance even after consecutive five cycles on the trot verified the strong photo-stability and reusability of our CuBi composite.

Monitoring cis-to-trans isomerization of azobenzene using Brillouin microscopy

Brillouin spectroscopy is commonly used to study the acoustic properties of materials. Here we explored its feasibility in studying the photoinduced isomerization of azobenzene. The isomerization of azobenzene changes the solution elastic modulus, and Brillouin scattering is sensitive to these changes. In this study, we experimentally demonstrated the photoswitching of azobenzene in DMSO using our home-made virtually imaged phased array-based high-resolution optical Brillouin spectrometer, and confirmed the results by ultraviolet–visible spectrophotometry. Remarkable Brillouin frequency shift variations were quantitatively recorded upon irradiation, and it was found that this method can indeed be used to monitor the isomerization process in situ. Importantly, our strategy also allows us to provide the relationship between the fraction of trans- and cis- azobenzene and the Brillouin frequency shift. This shows that Brillouin spectroscopy has broad prospects for the characterization of azobenzene isomerization and other photoresponsive materials.

Photocatalytic removal of some selected antibiotics in polluted water system by graphitic carbon nitride-enhanced vanadium ferrite (VFe2O4@g-C3N4)

Antibiotics such as sulfamethoxazole (SUF), ciprofloxacin (CIP) and erythromycin (ERY) are frequently detected in water systems without being efficiently removed during water treatment. This study synthesized a graphitic carbon nitride-enhanced vanadium ferrite (VFe2O4@g-C3N4) as a photocatalyst for degrading SUF, CIP and ERY in an aqueous solution. VFe2O4@g-C3N4 was characterized with X-ray diffractometry (XRD), thermogravimetry analysis (TGA), ultraviolet (UV)-visible spectrophotometry, scanning electron microscope (SEM) and transmission electron microscope (TEM). The XRD characterization of VFe2O4@g-C3N4 revealed diffraction patterns with a crystallite size of 22.45 nm and a bandgap energy of 1.94 eV. The SEM image revealed the surface to be rough with irregular particle shape and size. The TEM image showed an average particle size of 92.47 nm. VFe2O4@g-C3N4 exhibited a degradation efficiency, which showed complete removal of SUF (100 %) from solution while the efficiency towards CIP is 94 ± 0.60 % and 90 ± 0.8 % towards ERY. The best photocatalytic performance was achieved with 0.12 g L−1 of VFe2O4@g-C3N4 and pH = 7.0 as the optimal conditions for achieving complete removal of SUF, CIP and ERY at a concentration lower than 10.00 mg L−1 under visible-light irradiation. The photodegradation of SUF, CIP and ERY by VFe2O4@g-C3N4 was found to be promoted by ROS with ˙OH and SO4˙− radicals playing a significant role. VFe2O4@g-C3N4 demonstrated a regeneration capacity that is above 90 % at the 10th cycle of regeneration treatment, suggesting it to be stable and reusable with the X-ray diffraction pattern remaining unchanged and no leaching of VFe2O4@g-C3N4 into solution. The result from the study reveals VFe2O4@g-C3N4 as a promising photocatalyst for removing antibiotics from an aqueous solution.

Characterization of biotinylated human ACE2 and SARS-CoV-2 Omicron BA.4/5 spike protein reference materials

Accurate diagnostic and serology assays are required for the continued management of the COVID-19 pandemic yet spike protein mutations and intellectual property concerns with antigens and antibodies used in various test kits render comparability assessments difficult. As the use of common, well-characterized reagents can help address this lack of standardization, the National Research Council Canada has produced two protein reference materials (RMs) for use in SARS-CoV-2 serology assays: biotinylated human angiotensin-converting enzyme 2 RM, ACE2-1, and SARS-CoV-2 Omicron BA.4/5 spike protein RM, OMIC-1. Reference values were assigned through a combination of amino acid analysis via isotope dilution liquid chromatography tandem mass spectrometry following acid hydrolysis, and ultraviolet–visible (UV–Vis) spectrophotometry at 280 nm. Vial-to-vial homogeneity was established using UV–Vis measurements, and protein oligomeric status, monitored by size exclusion liquid chromatography (LC-SEC), was used to evaluate transportation, storage, and freeze–thaw stabilities. The molar protein concentration in ACE2-1 was 25.3 ± 1.7 µmol L−1 (k = 2, 95% CI) and consisted almost exclusively (98%) of monomeric ACE2, while OMIC-1 contained 5.4 ± 0.5 µmol L−1 (k = 2) spike protein in a mostly (82%) trimeric form. Glycoprotein molar mass determination by LC-SEC with multi-angle light scattering detection facilitated calculation of corresponding mass concentrations. To confirm protein functionality, the binding of OMIC-1 to immobilized ACE2-1 was investigated with surface plasmon resonance and the resulting dissociation constant, KD ~ 4.4 nM, was consistent with literature values.Graphical

Application of Turbiscan Lab® to study the mechanism of fining in red wine using a specific yeast protein extract: A comparison with gelatine

Fining of wines using proteins is a standard practice in the winemaking process. Gelatine is a common fining agent used for red wines. However, the consumer demand for wines that are free of animal-derived products has reinforced the search for alternative protein sources such as yeast origin as the latter is originally present in wine. In 2012, the International Organization of Vine and Wine (OIV) authorized yeast protein extract (YPE) as a processing aid for the fining of musts and wines (OIV-Eno 452–2012). The present work aimed at better understanding the fining mechanisms of a specific YPE, to evaluate the part played by interactions in solution with polyphenols, but also at the interfaces with suspended particles. Polyphenols from the soluble phase of red wine were separated from the suspended particles by centrifugation, and these particles were resuspended in a wine model solution. Interactions with YPE were studied with each fraction separately through static multiple light scattering (SMLS) using the Turbiscan Lab® apparatus and optical microscopy. The impact on wine color and astringency was assessed by UV–visible spectrophotometry and BSA assay test. Faster aggregation and sedimentation kinetics were observed with gelatine than with YPE, but the levels of clarification and lees were similar for both fining agents after a couple of hours (4 h maximum). Gelatine resulted in higher tannin and pigment removal, likely to decrease astringency but also derived pigments involved in red wine color stability. Meanwhile, the impact of the YPE was moderate, likely to modulate astringency while preserving wine color and structure. In addition to interacting directly with polyphenols in solutions such as gelatine, YPE exhibited the additional ability to trap particles and promote their sedimentation in the absence of tannins. This double performance of the YPE used in this work, is likely to guarantee an effective fining of red wines as well as for low tannin content matrices such as rosé and white wines.

Surface characterization of consolidated earthen substrates using an innovative multi-analytical strategy

This study evaluates the combined use of innovative non-destructive methods and standard laboratory techniques for assessing the surface effects of various consolidation treatments (i.e., bacterial biomineralization, alkaline activation, colloidal dispersions containing nanolime or nanosilica, and ethyl silicate as a standard) on earthen building materials. It demonstrates that novel portable equipment (i.e., portable digital microscope, air permeameter, and mobile surface (contact angle) analyzer) and advanced strategies for the application and data interpretation of conventional analytical and testing methods (i.e., scanning electron and confocal microscopy, Leeb hardness testing, and visible light spectrophotometry) can yield complementary and extremely valuable quantitative results for the evaluation of consolidation treatments on such complex substrates. Our multi-analytical approach allows a detailed characterization of surface and near-surface features of treated earthen mock-ups. It is possible to disclose significant differences in the film-forming propensity and in-depth distributions of consolidants and their effect on key properties such as surface roughness and appearance, permeability, water behavior, and mechanical properties. Even though, the substrate's inhomogeneity and surface texture has proven to be especially challenging, this methodology offers a promising strategy for long-term in-situ monitoring of treatment performance and weathering behavior of built heritage materials.

Oligoelectrolyte-mediated, pH-triggered release of hydrophobic drugs from non-responsive micelles: Influence of oligo(2-vinyl pyridine)-loading on drug-loading, release and cytotoxicity

pH-responsive polymeric micelles have been extensively studied for nanomedicine and take advantage of pH differentials in tissues for the delivery of large doses of cytotoxic drugs at specific target sites. Despite significant advances in this area, there is a lack of versatile and adaptable strategies to render micelles pH-responsive that could be widely applied to different payloads and applications. To address this deficiency, we introduce the concept of oligoelectrolyte-mediated, pH-triggered release of hydrophobic drugs from non-responsive polymeric micelles as a highly effective approach with broad scope. Herein, we investigate the influence of the oligoelectrolyte, oligo(2-vinyl pyridine) (OVP), loading and polymer molecular weight on the pH-sensitivity, drug loading/release and cytotoxicity of poly(ethylene glycol-b-ε-caprolactone) (PEG-b-PCL) micelles using copolymers with either short or long hydrophobic blocks (PEG4PCL4 and PEG10PCL10, respectively). The micelles were characterized as a function of pH (7.4 to 3.5). Dynamic light scattering (DLS) revealed narrow particle size distributions (PSDs) for both the blank and OVP-loaded micelles at pH 7.4. While OVP encapsulation resulted in an increase in the hydrodynamic diameter (Dh) (cf. blank micelles), a decrease in the pH below 6.5 led to a decrease in the Dh consistent with the ionization and release of OVP and core collapse, which were further supported by proton nuclear magnetic resonance (1H NMR) spectroscopy and UV–visible (UV–vis) spectrophotometry. The change in zeta potential (ζ) with pH for the OVP-loaded PEG4PCL4 and PEG10PCL10 micelles was different, suggesting that the location/distribution of OVP in the micelles is influenced by the polymer molecular weight. In general, co-encapsulation of drugs (doxorubicin (DOX), gossypol (GP), paclitaxel (PX) or 7-ethyl-10-hydroxycamptothecin (SN38)) and OVP in the micelles proceeded efficiently with high encapsulation efficiency percentages (EE%). In vitro release studies revealed the rapid, pH-triggered release of drugs from OVP-loaded PEG10PCL10 micelles within hours, with higher OVP loadings providing faster and more complete release. In comparison, no triggered release was observed for the OVP-loaded PEG4PCL4 micelles, implying a strong molecular weight dependency. In metabolic assays the drug- and OVP-loaded PEG10PCL10 micelles were found to result in significant enhancement of the cytotoxicity compared to drug-loaded micelles (no OVP) or other controls. Importantly, micelles with low OVP loadings were found to be nearly as effective as those with high OVP loadings. These results provide key insights into the tunability of the oligoelectrolyte-mediated approach for the effective formulation of pH-responsive micelles and pH-triggered drug release.

Mesoporous Oxidized Mn-Ca Nanoparticles as Potential Antimicrobial Agents for Wound Healing.

Managing chronic non-healing wounds presents a significant clinical challenge due to their frequent bacterial infections. Mesoporous silica-based materials possess robust wound-healing capabilities attributed to their renowned antimicrobial properties. The current study details the advancement of mesoporous silicon-loaded MnO and CaO molecules (HMn-Ca) against bacterial infections and chronic non-healing wounds. HMn-Ca was synthesized by reducing manganese chloride and calcium chloride by urotropine solution with mesoporous silicon as the template, thereby transforming the manganese and calcium ions on the framework of mesoporous silicon. The developed HMn-Ca was investigated using scanning electron microscopy (SEM), transmission electron microscope (TEM), ultraviolet-visible (UV-visible), and visible spectrophotometry, followed by the determination of Zeta potential. The production of reactive oxygen species (ROS) was determined by using the 3,3,5,5-tetramethylbenzidine (TMB) oxidation reaction. The wound healing effectiveness of the synthesized HMn-Ca is evaluated in a bacterial-infected mouse model. The loading of MnO and CaO inside mesoporous silicon enhanced the generation of ROS and the capacity of bacterial capture, subsequently decomposing the bacterial membrane, leading to the puncturing of the bacterial membrane, followed by cellular demise. As a result, treatment with HMn-Ca could improve the healing of the bacterial-infected wound, illustrating a straightforward yet potent method for engineering nanozymes tailored for antibacterial therapy.

Comparative evaluation of zinc oxide nanoparticles (ZnONPs): Photocatalysis, antibacterial, toxicity and genotoxicity

This study compares the physicochemical, photocatalytic, antimicrobial, toxicity and genotoxic properties of zinc oxide nanoparticles (ZnONPs) produced by hydrothermal and sol–gel methods as an alternative biomaterial. The comparative antibacterial activities, toxicity and DNA damage effects of ZnONPs on Drosophila melanogaster were determined using different doses. The study also investigates the effects of ZnONPs on malondialdehyde (MDA) and glutathione (GSH) levels, as well as superoxide dismutase (SOD) and catalase (CAT) activity. The structural, optical, and morphological properties of ZnONPs were investigated using X-ray diffractometer (XRD), UV–Visible spectrophotometry (UV–Vis), and field emission scanning electron microscopy (FESEM). The photocatalytic activity of ZnONPs in methylene blue solution was determined, and a high photocatalytic efficiency of 87 % was achieved in a short time. ZnONPs were found to have a significant antimicrobial effect on Streptococcus mutans ATCC 10449. Additionally, ZnONPs were non-toxic doses and did not cause DNA damage. In conclusion, ZnONPs synthesized can be safely used as filling material and bracket material especially in the field of dentistry since they are non-toxic, have a strong antimicrobial effect on S. mutans and do not cause DNA damage.

A comparative study between aqueous and methanol solutions of barium hydroxide: implications for applying barium protectants in gypsification calcareous relics

Gypsification is a common problem in weathered calcareous relics. In previous studies, the solutions of barium hydroxide in water and methanol were used as protectants for gypsification calcareous relics and showed significant differences in permeability. In this study, the underlying reasons for permeability differences between these two solutions were investigated using optical microscopy, ultraviolet–visible spectrophotometry, X-ray diffractometry, Fourier transform infrared spectroscopy, the phenolphthalein test and physical property characterizations. The results indicated that the permeability differences were primarily caused by the solutions’ reactivity. Specifically, owing to the high reactivity of barium hydroxide in water, it reacted rapidly with atmospheric CO2 and gypsum (the weathering product) to generate barium carbonate, barium sulfate and calcium hydroxide precipitates. These precipitates hindered the penetration of solution into weathered relics. In contrast, barium hydroxide in methanol did not react with atmospheric CO2 or weathered relics, which also kept the solution in a liquid state during the infiltration process. Therefore, the solution of barium hydroxide in methanol exhibited high permeability. Based on the above findings, this study is meaningful for applying barium protectants in the conservation of gypsification calcareous relics.

Schoenoplectus californicus (Cyperaceae) amorphous silica contribution to the silicon cycle in pampean shallow lakes: an analysis of spatio-temporal variation and silicon–lignin relations

Context Phytoliths constitute an important source of silicon in terrestrial and aquatic ecosystems. Schoenoplectus californicus (C.A.Mey.) Soják (Cyperaceae) is an important phytolith producer. Aims We investigated the spatio-temporal variation in phytolith content of S. californicus in shallow lakes of the Pampean region, considering biomass and its relation to soil silicon content and lignin content. Methods Calcination techniques were applied to quantify phytoliths. The biomass was estimated by destructive methods. Soil silicon concentration was determined through ultraviolet–visible spectrophotometry by means of the silicomolybdate method. For lignin determination, a fibre analyser and sulfuric acid were used. Key results No significant differences were observed in the spatio-temporal analysis. There were no differences in the biomass estimation and in the phytolith per m2 contribution. Regarding soil silicon content, when the concentration was low, the phytolith production was low. Lignin content remained constant between sites. No correlation was observed between phytolith and lignin content. Conclusions S. californicus is an accumulator of amorphous silica, generating a constant quantity of phytoliths over the years and between sites. The variation in some environmental conditions does not seem to be enough to be reflected in plant silica production. No relation between lignin and silica was found, perhaps due to their different roles in plant structure. Implications The inclusion of other wetlands with more contrasting conditions may reveal the environmental constraints for the amorphous silica production. This study shows the importance of this community as a silicon source, and the implications of its displacement by other communities or urban development.