Field-emission Electron Microscopy Research Articles

Investigating the in-vitro bioactivity, biodegradability and drug release behavior of the newly developed PES/HA/WS biocompatible nanocomposites as bone graft substitute

The nucleation of carbonate-containing apatite on the biomaterials surface is regarded as a significant stage in bone healing process. In this regard, composites contained hydroxyapatite (Ca10(PO4)6(OH)2, HA), wollastonite (CaSiO3, WS) and polyethersulfone (PES) were synthesized via a simple solvent casting technique. The in-vitro bioactivity of the prepared composite films with different weight ratios of HA and WS was studied by placing the samples in the simulated body fluid (SBF) for 21 days. The results indicated that the the surface of composites containing 2 wt% HA and 4 wt% WS was completely covered by a thick bone-like apatite layer, which was characterized by Grazing incidence X-ray diffraction, attenuated total reflectance–Fourier transform infrared spectrometer, field emission electron microscopy and energy dispersive X-ray analyzer (EDX). The degradation study of the samples showed that the concentration of inorganic particles could not influence the degradability of the polymeric matrix, where all samples expressed similar dexamethasone (DEX) release behavior. Moreover, the in-vitro cytotoxicity results indicated the significant cyto-compatibility of all specimens. Therefore, these findings revealed that the prepared composite films composed of PES, HA, WS and DEX could be regarded as promising bioactive candidates with low degradation rate for bone tissue engineering applications.

Blaze-angle led dark-blue iridescence and superhydrophobicity features of non-morpho Euploea midamus butterfly wing scale

We report on backlit iridescent blue structural coloration as well as superhydrophobicity in a non-morpho butterfly of Euploea midamus (blue-spotted crow) belonging to the Lepidoptera order. Select forewing and hindwing parts were characterized by employing optical microscopy, field emission electron microscopy, UV–vis-NIR spectrophotometry, and an advanced contact angle meter. As substantiated from variable incident angle reflectance spectra and chromaticity plots, the apparent visual effect is most pronounced in the forewing case and at an incident angle of 30–40°, with reflectance peak maxima positioned at ~ 412 nm and 478 nm. Additionally, the forewing scale of this butterfly acts as an anti-reflection filter (< 460 nm) for p-polarized light, showing greater polarization anisotropy in the lower wavelength region. Numerical simulationand microstructure-based analytical calculations with blaze angle grating effects have been considered to elucidate the observed dark-blue iridescence at large. Moreover, both the forewing and hindwing of the butterfly exhibit the ‘lotus effect’, with a contact angle as high as of ~ 150°, low contact angle hysteresis (16° and 13°) as well as low roll-off angles (10° and 7°) to favor self-cleaning action. Theoretical calculations attributing to dual roughnesses would encompass micro-textured and nanoscale asperities within the wing scale interface. The scope of the bifunctional features including optical and dewetting responses in natural systems would provide valuable insights and clues for biomimetics, particularly in nanophotonic and nanocoating applications.

On the Feasibility of Rugose Lipid Microparticles in Pressurized Metered Dose Inhalers with Established and New Propellants.

Pressurized metered dose inhalers (pMDIs) require optimized formulations to provide stable, consistent lung delivery. This study investigates the feasibility of novel rugose lipid particles (RLPs) as potential drug carriers in pMDI formulations. The physical stability of RLPs was assessed in three different propellants: the established HFA-134a and HFA-227ea and the new low global-warming-potential (GWP) propellant HFO-1234ze. A feedstock containing DSPC and calcium chloride was prepared without pore forming agent to spray dry two RLP batches at inlet temperatures of 55 °C (RLP55) and 75 °C (RLP75). RLPs performance in pMDI formulations was compared to two reference samples that exhibit significantly different performance when suspended in propellants: well-established engineered porous particles and particles containing 80% trehalose and 20% leucine (80T20L). An accelerated stability study at 40°C and relative humidity of 7% ± 5% was conducted over 3months. At different time points, a shadowgraphic imaging technique was used to evaluate the colloidal stability of particles in pMDIs. Field emission electron microscopy with energy dispersive X-ray spectroscopy was used to evaluate the morphology and elemental composition of particles extracted from the pMDIs. After 2weeks, all 80T20L formulations rapidly aggregated upon agitation and exhibited significantly inferior colloidal stability compared to the other samples. In comparison, both the RLP55 and RLP75 formulations, regardless of the propellant used, retained their rugose structure and demonstrated excellent suspension stability comparable with the engineered porous particles. The studied RLPs demonstrate great potential for use in pMDI formulations with HFA propellants and the next-generation low-GWP propellant HFO-1234ze.

Synthesis of cobalt nanoparticles in polystyrene matrix enhanced optical, dielectric, and magnetic properties

Recently, the development of particles fortified polymer composites has grown significantlydue to their intelligent uses in many fields.Cobalt nanoparticles' impact on the dielectric, optical, and magnetic properties of cobalt/polystyrene (Co/PS) nanocomposite films has been investigated. Co-NPs were preparedusing the reduction method and loadedintothepolystyrenematrixwith different concentrations(2, 5, 8, and 10 wt.%),forming nanocompositefilms. X-ray diffraction XRD was used to describe the structure of the produced films. The results showed a hexagonal (hcp) structure with ε phase of the Co-NPs in the PS matrix. The topography of the cross-section of nanocomposite films was scanned through a field emission electron microscope (FE-SEM). The high-resolution transmission electron microscope (HR-TEM) was used to examine the morphology of the produced Co-NPs. Zetasizer considered the charge and particle size distribution of the prepared Co-NPs powder. At room temperature, dielectric spectroscopy looked at the dielectric characteristics over a frequency range from 10−1 - 107 Hz. The UV analyzed the optical properties of nanocomposite films–VIS technique. The optical bandgap of the nanocomposite films is a direct allowed transition and decreases from 4.51 to 3.69e, which increases the absorption coefficient. A vibrating sample magnetometer (VSM) was used to measure the magnetic hysteresis loops of the produced films at room temperature. The ferromagnetic behavior of all samples was evident, and there was an apparent magnetic hysteresis. All samples exhibited high coercivity, where the exchange bias decreased from 28.02 Oe to 1.42 Oe with increasing Co wt% in PS. The present work found that the Co/PS nanocomposite films loaded with various concentrations of Co-NPs and tuned properties may be suitable for use in electrical energy storage, photonic devices, and some magnetic applications, such as spintronic devices.

Photocatalytic bio‐inspired PDA‐RGO/g‐C3N4 nanocomposite incorporated PES membrane for removal of environmental antibiotic pollutants

AbstractBACKGROUNDMembrane technology makes it more suitable for the treatment of environmental polluted organic wastewater. Membrane fouling is one of the major concerns in commercial membranes. To overcome this issue, photocatalytic nanomaterials are embedded into the membrane to enhance its surface nature and reusability. In this investigation, polydopamine functionalized graphene oxide (PDA‐RGO), graphite carbon nitride (g‐C3N4) and PDA‐RGO/g‐C3N4 nanomaterials were incorporated within polyethersulfone membrane fabricated via a phase inversion technique. These as‐prepared membranes’ functional groups and surface morphologies were investigated by Fourier transform infrared (FTIR) spectroscopy, atomic force microscopy (AFM) and field emission electron microscopy (FESEM). These as‐prepared membranes were investigated for photocatalytic activity under visible‐light‐driven photodegradation by environmental pollutants such as Rhodamine B (RhB) and Norfloxacin (NOR).RESULTSCompared with pristine PES membrane, the PDA‐RGO/g‐C3N4‐PES nanocomposite membrane showed higher photocatalytic activity for Rhodamine B 94.6% and Norfloxacin 96.8%, also reached greater water flux 189 L m−2 h−1. Therefore, the bio‐inspired nanocomposite‐modified PDA‐RGO/g‐C3N4 photocatalytic membrane could have huge potential in processing environmentally polluted water.CONCLUSIONSPDA‐RGO/g‐C3N4‐PES nanocomposite membrane improved the membrane hydrophilicity, water flow, anti‐fouling performance, rejection studies and photocatalytic degradation than the pristine membrane. The synergistic result of PDA‐RGO and g‐C3N4 exhibits better photodegradation efficiency of the membrane towards environmental pollutants. © 2024 Society of Chemical Industry (SCI).

Chiroptical Strain Sensors from Electrospun Cadmium Sulfide Quantum-Dot Fibers.

Controllable synthesis of homochiral nano/micromaterials has been a constant challenge for fabricating various stimuli-responsive chiral sensors. To provide an avenue to this goal, we report electrospinning as a simple and economical strategy to form continuous homochiral microfibers with strain-sensitive chiroptical properties. First, electrospun homochiral microfibers from self-assembled cadmium sulfide (CdS) quantum dot magic-sized clusters (MSCs) are produced. Highly sensitive and reversible strain sensors are then fabricated by embedding these chiroptically active fibers into elastomeric films. The chiroptical response on stretching is indicated quantitatively as reversible changes in magnitude, spectral position (wavelength), and sign in circular dichroism (CD) and linear dichroism (LD) signals and qualitatively as a prominent change in the birefringence features under cross-polarizers. The observed periodic twisted helical fibrils at the surface of fibers provide insights into the origin of the fibers' chirality. The measurable shifts in CD and LD are caused by elastic deformations of these helical fibrillar structures of the fiber. To elucidate the origin of these chiroptical properties, we used field emission-electron microscopy (FE-SEM), atomic force microscopy (AFM), synchrotron X-ray analysis, polarized optical microscopy, as well as measurements to isolate the true CD, and contributions from photoelastic modulators (PEM) and LD. Our findings thus offer a promising strategy to fabricate chiroptical strain-sensing devices with multiple measurables/observables using electric-field-assisted spinning of homochiral nano/microfibers.

Insulin Conformation Changes in Hybrid Alginate-Gelatin Hydrogel Particles.

There is a strong need to develop an insulin delivery system suitable for oral administration and preserving natural (α-helix) insulin conformation. In this work, we fabricated alginate-gelatin hydrogel beads for insulin encapsulation. Altering matrix composition and crosslinking agents has resulted in various surface morphologies and internal spatial organization. The structures of the insulin-loaded matrices were studied using optical and field emission electronic microscopy. We use FTIR spectroscopy to identify insulin conformation changes as affected by the hydrogel matrices. It was found that blended alginate-gelatin matrices demonstrate better encapsulation efficiency and stronger swelling resistance to a simulated gastric environment than sodium alginate beads crosslinked with the CaCl2. FTIR measurements reveal conformation changes in insulin. It is also confirmed that in the presence of gelatin, the process of insulin fibrinogenesis ceases due to intermolecular interaction with the gelatin. Performed molecular modeling shows that dipole-dipole interactions are the dominating mechanism that determines insulin behavior within the fabricated matrix.

Improving barrier properties of polyethylene/Fe2O3‐modified nanographene nanocomposites in a magnetic field

AbstractThe present work aims at improving the barrier properties of high molecular weight Polyethylene/ graphene nanoplatelets (HMWPE/GnP) nanocomposites by aligning the embedded modified graphene nanoparticles in a magnetic field. Graphene nanoplatelets (GnP) were modified by magnetic Fe2O3 to produce Fe2O3‐modified Graphene, GnP‐mFe2O3. The magnetic properties of Fe2O3 were previously characterized by the vibrating sample magnetometer (VSM) method and resulting GnP‐mFe2O3 nanoparticles were characterized by Fourier transform infrared (FTIR) analysis. HMWPE/GnP nanocomposites were prepared via melt mixing. The prepared nanocomposites were sheeted at high temperatures in a magnetic field using a hot press. The barrier properties of prepared films, HMWPE/GnP and HMWPE/GnP‐mFe2O3 were characterized by carrying out a permeation to oxygen experiment as a function of GnP and GnP‐mFe2O3 contents. A decrease in gas transmission rate (GTR) was observed for the samples after being subjected to the magnetic field compared to the non‐treated sample. The results of differential scanning calorimetry (DSC) and field emission electron microscopy (FESEM) experiments confirmed the orientation of GnP‐mFe2O3 nanoparticles in nanocomposites.

An experimental look into efficient quaternary Bi5O7I/Bi(IO3)3/Bi2(IO4) (IO3)3/BiOIO3 photocatalytic composite

The prototypical toxic dye rhodamine B (RhB) is perhaps one of the most abundant pollutants in industrial wastewater. Its efficient photocatalytic degradation through composite photocatalysts is crucial for environmental remediation. Here, we synthesized quaternary Bi5O7I/Bi(IO3)3/Bi2(IO4)(IO3)3/BiOIO3 bismuth iodate composites through facile hydrothermal and solvothermal methods. The coexistence of multiple bismuth iodate phases was confirmed by x-ray diffraction analysis, room temperature Raman, and Fourier-transform infrared spectroscopy. The desired chemical states of Bi, I, and O inside the composites were confirmed by x-ray photoelectron spectroscopy. Field emission electron microscopy revealed flower-shaped nanosheet morphology for the composite synthesized at 120 °C, whereas randomly shaped nanoparticles with an average size of 80 nm were formed in the composite calcined at 400 °C. High-resolution transmission electron microscopy further corroborated the existence of multiple phases in the composites. The diffuse reflectance spectroscopy confirmed the optical absorption edges of the composites to be located within the visible range of 1.68–3.16 eV. The flower-shaped quaternary bismuth iodate composite demonstrated 100% degradation of RhB dye within 40 min of optical exposure. This quaternary bismuth iodate composite is suitable for solar harvesting-driven toxic dye remediation.

Revealing the mechanism of citral induced entry of Vibrio vulnificus into viable but not culturable (VBNC) state based on transcriptomics

Citral has attracted much attention as a safe and effective plant-derived bacteriostatic agent. However, the ability of citral to induce the formation of VBNC state in Vibrio vulnificus has not been evaluated. In the present study, V. vulnificus was shown to be induced to form the VBNC state at 4.5 h and 3 h of citral treatment at 4MIC and 6MIC. Moreover, the citral-induced VBNC state of V. vulnificus maintained some respiratory chain activity and was able to recover well in both APW media, APW media supplemented with 5 % (v/v) Tween 80 and 2 mg/mL sodium pyruvate. Field emission and transmission electron microscopy showed that the external structure of the citral-induced VBNC V. vulnificus cells was shortened to short rods, with folded cell membrane, rough cell surface, and dense cytoplasm and loose nuclear material in the internal cell structure. In addition, the possible molecular mechanisms of citral-induced formation and recovery of V. vulnificus in the VBNC state were explored by transcriptomics. Transcriptome analyses revealed that 1118 genes were significantly altered upon entry into the VBNC state, and 1052 genes were changed after resuscitation. Most of the physiological activities related to energy production were inhibited in the citral-induced VBNC state of V. vulnificus; however, the bacteria retained its pathogenicity. The citral-induced resuscitation of V. vulnificus in the VBNC state selectively restored the activity of some genes related to bacterial growth and reproduction. Meanwhile, the expression levels of other genes may have been influenced by citral-induced resuscitation after the formation of the VBNC state. In conclusion, this study evaluated and analyzed the ability and possible mechanism of citral on the formation of VBNC state and the recovery of VBNC state of V. vulnificus, and made a comprehensive assessment for the safety of citral application in food production.

Antimicrobial and antibiofilm properties of selenium-chitosan-loaded salicylic acid nanoparticles for the removal of emerging contaminants from bacterial pathogens.

In this study salicylic acid loaded containing selenium nanoparticles was synthesized and called SA@CS-Se NPs. the chitosan was used as a natural stabilizer during the synthesis process. Fourier transforms infrared spectroscopy (FTIR), Powder X-ray diffraction (XRD), field emission electron microscopy (FESEM), and transmission electron microscopy (TEM) were used to describe the physicochemical characteristics of the SA@CS-Se NPs. The PXRD examination revealed that the grain size was around 31.9nm. TEM and FESEM techniques showed the spherical shape of SA@CS-Se NPs. Additionally, the analysis of experiments showed that SA@CS-Se NPs have antibacterial properties against 4 ATCC bacteria; So that with concentrations of 75, 125, 150, and 100µg/ml, it inhibited the biofilm formation of Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, and Staphylococcus aureus respectively. Also, at the concentration of 300µg/ml, it removed 22.76, 23.2, 10.62, and 18.08% biofilm caused by E. coli, P. aeruginosa, B. subtilis, and S. aureus respectively. The synthesized SA@CS-Se NPs may find an application to reduce the unsafe influence of pathogenic microbes and, hence, eliminate microbial contamination.

Computational modelling and experimental investigation of micro-electrochemical discharge machining by controlling the electrolyte temperature

Glass vias are emerging as a favourable option for radiofrequency-based micro-electromechanical system packaging. For the micromachining of glass, electrochemical discharge machining (ECDM) could be the most suitable technique if issues pertaining to the process stability are addressed thoroughly. The electrolyte temperature has immense influence on the viscosity and conductivity of the electrolyte, which percolate the stability of the ECDM process. Therefore, this article investigates the effects of the electrolyte temperature and applied voltage on the performance characteristics of ECDM for the micromachining of borosilicate glass. The machining rate (MR) and hole overcut (HOC) of the machined microholes are considered as performance characteristics. A 3D thermal-based finite element model (FEM) was developed for the thermal analysis in the machining zone. In the thermal analysis, the heat flux by thermal discharge was assumed to have Gaussian distribution, and accordingly, temperature profiles in the thermal zone were analyzed by controlling the electrolyte temperature and voltage at various levels. Further processing of temperature profiles in the thermal zone was utilized in the estimation of MR and HOC. Electrostatic-based FEM was utilized to assess the intensity of the electric field in the proximity of the tool electrode to analyze the probable locations of thermal discharge and its impact on the geometrical characteristics of the machined microholes. The simulation outcomes were validated experimentally, and show good agreement. A field emission electron microscope with energy dispersive spectroscopy was used for the characterization of the machined surface to observe the effect of the electrolyte temperature.

Promising photocatalytic activity of Ag2SO4-modified BiOCl/BFO heterostructures under visible light

ABSTRACT In this work, a simple co-precipitation method for the preparation of Ag2SO4@BiOCl@Bi25FeO40 (BFO) was developed. Ultraviolet–visible spectrophotometric analysis, X-ray diffraction patterns, Fourier transform infrared spectroscopy (FT-IR), and scanning field emission electron microscopy (FESEM) were performed to characterize the newly synthesized nanocomposite. In addition, the EDX method was used to determine the actual material quantities. The synthesized samples of Bi25FeO40 and Ag2SO4 Bi25FeO40 showed high absorption in the visible region. Furthermore, the photocatalytic activity was significantly improved by the addition of Ag2SO4. The results showed photcatalytic efficiency was reached to about 99% with 0.01 g of Ag2SO4@BiOCl@Bi25FeO40 in pH 4 under visible light. The isoelectric pH of the photocatalayst was obtained 5. Also, kinetic study showed a first order mechanism for photodegradation. Moreover, a mechanistic study was proposed for the newly synthesized heterostructures.

Synthesis and Characterizations of Molecularly Imprinted Polymer of Atrazine: Removal of Atrazine from Aqueous Samples

AbstractAtrazine (ATZ) is a widely used triazine herbicide in agriculture, however, it negatively affects the environment and human health. Therefore, a molecularly imprinted polymer (MIP) was employed for the selective removal of ATZ. In this study, MIPs were produced by precipitation polymerization using ATZ as the target molecule, methacrylic acid (MAA), acrylamide (AAm), and 2‐vinylpyridine (2VP) as functional monomers and ethylene glycol dimethacrylate (EGDMA) as cross‐linker, respectively. MIP characterizations were performed using Fourier Infrared spectroscopy (FTIR) and Field Emission Electron Microscopy (FESEM). The batch binding study revealed that MIP (2VP) exhibited the highest rebinding efficiency (88.44 %) among the MIPs. Furthermore, MIP (2VP) was analyzed by Energy‐Dispersive X‐ray spectroscopy (EDX), Brunauer‐Emmett‐Teller (BET) analysis, and thermogravimetric analysis (TGA). Adsorption studies revealed that the optimum conditions for maximum adsorption efficiency were 8 ppm ATZ solution at pH 7, using 0.3 g of MIP (2VP). MIP (2VP) demonstrated higher selectivity towards ATZ than the Ametryn (AME) a competitive interferent, with a relative selectivity coefficient of 2.77. MIP (2VP) successfully removed ATZ from distilled water (95.39 %), tap water (88.16 %) and river water (86.75 %). These findings contributed for the development of MIP for the removal of ATZ, which would be helpful in the protection of ecosystem and human health in future.

ELECTROCATALYSIS OF COBALT DOPED CeO2/rGO NANOCOMPOSITE FOR OXIDATION OF METHANOL AND FORMIC ACID

In this study,a novel cobalt-doped cerium oxide (CeO2)on reduced graphene oxide (rGO) substrate was successfully prepared through a hydrothermal method.The comprehensive characterization of the synthesized nanocomposite involved X-ray diffraction studies (XRD),Raman spectrum analysis,High Resolution Transmission Electron microscopy (HRTEM), and Field Emission Electron Microscopy (FE-SEM).The effective surface area of CeO2/rGO and Co-CeO2/rGO was determined using the Randles-Sevecik equation,revealing values of 4.02X10-5 cm2 and 6.35X10-5 cm 2 ,respectively.Cyclic Voltammetry (CV) was employed to investigate the electrochemical reversibility behavior, demonstrating promising results for Co-CeO2/rGO nanocomposite.Electrochemical impedance spectroscopy(EIS) further highlighted low charge transfer resistance (Rct) and enhanced double-layer capacitance (Cdl).Notably, the synthesized nanocomposite exhibited excellent electrocatalytic activity for methanol and formic acid oxidation in an acidic medium. Overall, this work provides valuable insights into the synthesis characterization, and electrochemical performance of Co-CeO2/rGO nanocomposite, showcasing their potential applications in energy- related processes.

Biosynthesis of Gold Nanoparticles Using Quince Seed Water Extract and Investigation of Their Anticancer Effect Against Cancer Cell Lines.

In this study, gold nanoparticles (Au-NPs) were synthesized using HAuCl4 and quince seed mucilage (QSM) extract, which was characterized by conventional methods including Fourier transforms electron microscopy (FTIR), UV-Visible spectroscopy (UV-Vis), Field emission electron microscopy (FESEM), Transmission electron microscopy (TEM), Dynamic light spectroscopy (DLS), and Zeta-potential. The QSM acted as reductant and stabilizing agents simultaneously. The NP's anticancer activity was also investigated against osteosarcoma cell lines (MG-63), which showed an IC50 of [Formula: see text]/mL.

Optical characterization of SnS nanowires by chemical vapor deposition method: A combined experimental and DFT study

We report on synthesis of SnS nanowires grown on Si substrates by chemical vapor deposition method at various growth temperatures between 800 and 950 °C, using gold catalyst. X-ray diffraction and Raman analyses confirmed crystalline orthorhombic phase (Pbnm space group) formation. Field emission electron microscopy showed almost uniform morphology of nanowires with average diameter of 28–98 nm with variable length sizes. Diffused reflectance spectroscopy revealed an increasing bandgap with increasing growth temperature. Bandgap and optical properties of SnS were also studied using density functional theory, showing excellent agreement between experimentally and theoretically calculated bandgap values, suitable for potential optical applications.

Synthesis of molecularly imprinted polymer by precipitation polymerization for the removal of ametryn

Ametryn (AME) is a triazine herbicide which is mainly used to kill unwanted herbs in crops. Despite its importance in agriculture, the usage of AME also poses a risk to humans and the ecosystem due to its toxicity. Hence, it is important to develop a method for the effective removal of AME from various water sources which is in the form of molecular imprinting polymer (MIP). In this study, MIP of AME was synthesized via precipitation polymerization using AME as the template molecule with three different functional monomers including methacrylic acid (MAA), acrylamide (AAm) and 2-vinylpyridine (2VP). The three different synthesized polymers namely MIP (MAA), MIP (AAm) and MIP (2VP) were characterized using Fourier Infra-red spectroscopy (FTIR) and Field Emission Electron Microscopy (FESEM). Then, the batch binding study was carried out using all three MIPs in which MIP (MAA) attained the highest rebinding efficiency (93.73%) among the synthesized polymers. The Energy-Dispersive X-ray spectroscopy (EDX) analysis, Brunauer–Emmett–Teller (BET) analysis and thermogravimetric analysis (TGA) were also conducted on the selected MIP (MAA). Adsorption studies including initial concentration, pH and polymer dosage were also conducted on MIP (MAA). In this study, the highest adsorption efficiency was attained at the optimum condition of 6 ppm of AME solution at pH 7 with 0.1 g of MIP (MAA). MIP (MAA) was successfully applied to remove AME from spiked distilled water, tap water and river water samples with removal efficiencies of 95.01%, 90.24% and 88.37%, respectively.Graphical

The comparative effects of visible light and UV-A radiation on the combined toxicity of P25 TiO2 nanoparticles and polystyrene microplastics on Chlorella sp.

The ubiquitous presence of TiO2 nanoparticles (nTiO2) and microplastics (MPs) in marine ecosystems has raised serious concerns about their combined impact on marine biota. This study investigated the combined toxic effect of nTiO2 (1 mg/L) and NH2 and COOH surface functionalized polystyrene MPs (PSMPs) (2.5 and 10 mg/L) on Chlorella sp. All the experiments were carried out under both visible light and UV-A radiation conditions to elucidate the impact of light on the combined toxicity of these pollutants. Growth inhibition results indicated that pristine nTiO2 exhibited a more toxic effect (38%) under UV-A radiation when compared to visible light conditions (27%). However, no significant change in the growth inhibitory effects of pristine PSMPs was observed between visible light and UVA radiation conditions. The combined pollutants (nTiO2 + 10 mg/L PSMPs) under UV-A radiation exhibited more growth inhibition (nTiO2 + NH2 PSMPs 66%; nTiO2 + COOH PSMPs 50%) than under visible light conditions (nTiO2 + NH2 PSMPs 55%; TiO2 + COOH PSMPs 44%). Independent action modeling indicated that the mixture of nTiO2 with PSMPs (10 mg/L) exhibited an additive effect on the algal growth inhibition under both the light conditions. The photoactive nTiO2 promoted increased production of reactive oxygen species under UV-A exposure, resulting in cellular damage, lipid peroxidation, and impaired photosynthesis. The effects were more pronounced in case of the mixtures where PSMPs added to the oxidative stress. The toxic effects of the binary mixtures of nTiO2 and PSMPs were further confirmed through the field emission electron microscopy, revealing specific morphological abnormalities. This study provides valuable insights into the potential risks associated with the combination of nTiO2 and MPs in marine environments, considering the influence of environmentally relevant light conditions and the test medium.

Ultrasonic processing of WO3 nanosheets integrated Ti3C2 MXene 2D-2D based heterojunctions with synergistic effects for enhanced water splitting and environmental remediation

This article describes a straightforward chemical procedure that involves hydrothermal and ultrasonic treatments to create a new 2D/2D ultrathin WO3/Ti3C2 heterojunctions. The features of the fabricated heterojunctions were characterized and examined by field emission electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), optical absorption spectroscopy (UV–Vis). By photodegrading an organic dye under the influence of visible light, the photocatalytic degradation capabilities of the heterojunctions were also investigated. The performance of WO3/Ti3C2 was superior to that of bare WO3, with a removal rate of 94% and a kinetic rate constant (k) that was approximately 3 times that of WO3. The creation of 2D/2D heterojunction was observed to encourage the spatial charge separation and increase the surface reactive sites, to result with the increased photocatalytic activity in WO3/Ti3C2 heterojunction. The photocurrent values discovered through photoelectrochemical studies further indicated Ti3C2′s active function in enhancing water-splitting performance. The impedance analysis examined by an electrochemical method revealed that heterojunctions might be helpful in accelerating the migration of charges quickly to get the outcomes seen.