Microscopy Techniques Research Articles

Pharmacognostic Characterization of Primula macrophylla by Light Microscopy, Scanning Electron Microscopy and Analytical Techniques.

Traditional medicinal systems have extensively used Primula macrophylla (Primulaceae) to treat a variety conditions, including bronchitis, asthma, joint pain, fever and so forth. This study determines various pharmacognostic and phytochemical standards helpful to ensure the purity, safety, and efficacy of medicinal plant P. macrophylla. In experimental section the Intact aerial parts, powdered materials, and extracts were examined macro- and microscopically and pharmacognostic standardization parameters were determined in accordance with the guidelines given by the World Health Organization. Parameters including extractive values, ash values, and loss on drying were determined. Preliminary phytochemical tests, fluorescence analysis, and chromatographic profiling were performed for the identification and standardization of P. macrophylla. The results of macroscopic studies revealed that leaves are farinose, alternating, foliage, toothed and flowers are unbranched, hermaphroditic, large, herbaceous, round, non-woody stem, roots are adventitious. Length of leave is 11 cm, flower 3 cm, stem 38 cm and root 18 cm. Odor is clove or Eucalyptus like, irritating smell and has pungent/ bitterness. Qualitative analysis confirmed that carbohydrates are not present and saponins, terpenoid, flavonoid, phenolic, phytosterol and fixed oils are not present. The atomic absorption spectrophotometer (AAS) showed the trace amounts of Pb (1.604 mg/L), As (-12.91 mg/L), Hg (7.102 mg/L), and Cd (0.226 mg/L) present. The internal structure of the plant was examined using light microscopy (LM) and scanning electron microscopy (SEM). The plant cross-sectional scans revealed several useful botanical properties. LM and SEM revealed important diagnostic features including stomata, phloem, xylem, spiral vessels, and trichomes and so forth. We conclude that the data generated from the present study help to authenticate the medicinally important plant P. macrophylla. This study is helpful for establishing the pharmacopeia standards in accordance with WHO guidelines.

Bimetallic PdPt nanoparticle-incorporated PEDOT:PSS/guar gum-blended membranes for enhanced CO2 separation.

To address the escalating demand for efficient CO2 separation technologies, we introduce novel membranes utilizing natural polymer guar gum (GG), conjugate polymer (poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)) PEDOT:PSS, and bimetallic PdPt nanoparticles. Bimetallic PdPt nanoparticles were synthesized using the wet chemical method and characterized using X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) techniques. The morphologies, chemical bonds, functional groups, and mechanical properties of the fabricated membranes were characterized using various techniques. Through meticulous fabrication and characterization, the binary blended membranes demonstrated enhanced homogeneity and smoothness in their structure, attributed to the interaction between the polymers, and superior CO2 permeability due to the amphiphilic nature of the PEDOT:PSS polymer. Gas separation experiments performed using H2, N2, and CO2 gases confirmed that the 20% PEDOT:PSS/GG blended membranes showed the best performance with sufficient mechanical properties. Moreover, the results demonstrated an increase of 172% in CO2 permeability and 138% in CO2/H2 selectivity, respectively. Furthermore, integrating bimetallic PdPt nanoparticles provided an additional 197% increase in CO2/H2 selectivity, owing to the unique catalytic activities of noble metal nanoparticles. The study not only underscores the transformative potential of polymer blending and noble metal engineering, but also highlights the significance of using natural polymers for sustainable environmental solutions.

A comparison of super-resolution microscopy techniques for imaging tightly packed microcolonies of an obligate intracellular bacterium.

Conventional optical microscopy imaging of obligate intracellular bacteria is hampered by the small size of bacterial cells, tight clustering exhibited by some bacterial species and challenges relating to labelling such as background from host cells, a lack of validated reagents, and a lack of tools for genetic manipulation. In this study, we imaged intracellular bacteria from the species Orientia tsutsugamushi (Ot) using five different fluorescence microscopy techniques: standard confocal, Airyscan confocal, instant Structured Illumination Microscopy (iSIM), three-dimensional Structured Illumination Microscopy (3D-SIM) and Stimulated Emission Depletion Microscopy (STED). We compared the ability of each to resolve bacterial cells in intracellular clumps in the lateral (xy) axis, using full width half-maximum (FWHM) measurements of a labelled outer membrane protein (ScaA) and the ability to detect small, outer membrane vesicles external to the cells. Comparing the techniques readily available to us (above), 3D-SIM microscopy, in combination with the shortest-wavelength dyes, was found overall to give the best lateral resolution. We next compared the ability of each technique to sufficiently resolve bacteria in the axial (z) direction and found 3D-STED to be the most successful method for this. We then combined this 3D-STED approach with a custom 3D cell segmentation and analysis pipeline using the open-source, deep learning software, Cellpose to segment the cells and subsequently the commercial software Imaris to analyse their 3D shape and size. Using this combination, we demonstrated differences in bacterial shape, but not their size, when grown in different mammalian cell lines. Overall, we compare the advantages and disadvantages of different super-resolution microscopy techniques for imaging this cytoplasmic obligate intracellular bacterium based on the specific research question being addressed.

Resolving viral structural complexity by super-resolution microscopy.

In this review, we discuss different super-resolution microscopy (SRM) techniques employed to study viral structures and virus composition with nanometric resolution. We describe the basic principles of the different microscopy methods utilized to break the light diffraction limit, enabling the study of protein composition in viral structures. Finally, we demonstrate for the first time the differential spatial distribution of two structural proteins in an individual baculovirus using single-molecule super-resolution microscopy. We discuss the future of these powerful methods for virology, medicine, and biotechnology applications.

Morphological features of synaptic structures associated with amyloid plaques in the human cerebral cortex

BACKGROUND: Synapse damage and loss are fundamental to the pathogenesis of Alzheimer’s disease (AD) and lead to reduced cognitive function. Therefore, the study of synaptic abnormalities is crucial for understanding the pathogenesis and progression of AD. Synaptophysin, a transmembrane protein of synaptic vesicles, is most widely used as an immunohistochemical marker of synapses. AIM: to study the morphological features of synaptophysin–containing elements in the human cerebral cortex with amyloid plaques. METHODS: This study was made on the cerebral cortex samples of men and women aged 65 to 94 years (n = 10). Synapses and amyloid plaques were simultaneously detected with a new original light microscopy technique. This technique is based on immunohistochemical staining for synaptophysin and histochemical staining of amyloid plaques with Alcian blue. RESULTS: Abnormal synaptophysin-immunopositive structures presumed to be dystrophic presynapses were found within most of the identified amyloid plaques. These structures have large sizes and indistinct shapes and are present exclusively within amyloid plaques. Interestingly, corpora amylacea were also identified in all samples. They have spherical shapes and are located mainly in the perivascular, periventricular, and subpial regions of the brain. In all analyzed samples, synaptophysin-immunopositive terminals surrounding corpora amylacea had normal morphology and density and showed no signs of pathology. CONCLUSION: In this work, abnormal synaptophysin-containing structures associated with amyloid plaques were found in the human cerebral cortex using the original staining technique. Further study of these structures holds promise for identifying new biomarkers of synaptic disorganization, including in Alzheimer's disease.

Aqueous Dispersion of Xenes by Liquid Phase Exfoliation of Monoelemental Crystals in Melamine Solution.

Αfter the impressive evolution of graphene and its derivatives, a large number of two dimensional (2D) materials with important optical and electrical properties have been successfully fabricated. Liquid phase exfoliation (LPE) of layered and non-layered materials has become a widely applied method for the preparation of 2D nanostructures with an extensive variety of applications. However, in most cases organic solvents are used as liquid phase which are often toxic and environmentally unfriendly and lead to low yields. In this work, we present water as a suitable liquid phase and dispersion medium for the exfoliation of layered and non-layered monoelemental solids from IVA, VA and VIA groups of the periodic table, such as silicon, tin, bismuth and tellurium. The 2D nanostructures, silicene, stanene, bismuthene and tellurene are therefore prepared by a completely sustainable and environmentally friendly method. The prepared Xenes, as they are called, are fully characterized by microscopic and spectroscopic techniques.

Novel polyvinyl alcohol-assisted MnO2-ZnO-CuO nanocomposites as an efficient photocatalyst for methylene blue degradation from wastewater.

Pristine ZnO (Z), MnO2 (M), CuO (C) photocatalysts and polyvinyl alcohol (PVA)-assisted MnO2-ZnO-CuO (MZC) nanocomposites were synthesized via the sol-gel method. The synthesized samples were characterized using thermal analysis (TGA), X-ray diffraction (XRD), dynamic light scattering (DLS), scanning electron microscopy (SEM), energy dispersive X-ray (EDS), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM) techniques. The thermal analysis results of the prepared nanomaterial confirmed that the suitable calcination temperature for the synthesis of these nanomaterials is 420 °C. In addition to the morphological and elemental composition, the characteristic diffraction peaks of the MZC nanomaterial were found to align with those of the pristine Z, M, and C photocatalysts. The photocatalytic activities of the synthesized nanomaterials for methylene blue (MB) degradation were evaluated under optimized conditions. The degradation efficiencies of Z, M, C, and MZC were found to be 45%, 57%, 66%, and 93%, respectively, for MB in 180 minutes. The MZC nanocomposite exhibited superior photocatalytic activity compared to the pristine materials, which is attributed to the synergetic effect of the Z, M, and C photocatalysts. The effects of pH, initial dye concentration, and catalyst load were also explored to determine the optimum conditions. The best photocatalytic efficiency was observed at pH 8, with a 130 mg L-1 catalyst load, and a 10 mg L-1 initial dye concentration. The efficiency of the MZC nanocomposite in real textile wastewater was also tested, achieving 80% degradation of pollutants within 180 minutes. Recycling experiments were conducted for four consecutive cycles under optimal conditions. The photodegradation efficiency for the first, second, third, and fourth cycles was 93%, 91%, 90%, and 89%, respectively, demonstrating high consistency in photodegradation performance across the four cycles. Moreover, a Z-scheme photocatalytic mechanism was proposed as a potential mechanism for the MZC photocatalytic system.

Quantification of Rapid Cooling of Glycerol/Water Solutions Based on Photoluminescence from Thioflavin T.

Rapid cooling to a solid state allows intermediates in chemical and biomolecular processes that occur in solution near room temperature to be trapped for subsequent measurements by magnetic resonance spectroscopies, electron microscopy, or other techniques. In time-resolved solid state nuclear magnetic resonance and rapid freeze-quench electron paramagnetic resonance studies, solutions are typically frozen by spraying into a cold bath or onto a cold metal surface. Although simulations suggest freezing on millisecond or submillisecond time scales, direct experimental measurements of cooling rates have been elusive. Here, we describe a method for quantification of rapid cooling rates based on measurements of temperature-dependent photoluminescence from thioflavin T (ThT). In our experiments, a jet of ThT solution in glycerol/water, with 10.8 m/s jet velocity and 30 μm diameter, freezes on a cold, rotating copper surface. Images of ThT photoluminescence on the copper surface indicate that the cooling rate of the solution increases linearly with the surface velocity over the 0.45-6.2 m/s range. At surface velocities greater than 3.8 m/s, the time to cool from 300 to 260 K or from 300 to 230 K is less than 100 μs or less than 700 μs. The experimental results do not agree quantitatively with calculations in which a layer of glycerol/water cools by thermal conduction when suddenly brought in contact with a cold copper surface. Discrepancies between experimental results and simplistic calculations illustrate the importance of direct measurements of cooling rates.

One step 4× and 12× 3D-ExM enables robust super-resolution microscopy of nanoscale cellular structures.

Super-resolution microscopy has become an indispensable tool across diverse research fields, offering unprecedented insights into biological architectures with nanometer scale resolution. Compared with traditional nanometer-scale imaging methods such as electron microscopy, super-resolution microscopy offers several advantages, including the simultaneous labeling of multiple target biomolecules with high specificity and simpler sample preparation, making it accessible to most researchers. In this study, we introduce two optimized methods of super-resolution imaging: 4-fold and 12-fold 3D-isotropic and preserved Expansion Microscopy (4× and 12× 3D-ExM). 3D-ExM is a straightforward expansion microscopy technique featuring a single-step process, providing robust and reproducible 3D isotropic expansion for both 2D and 3D cell culture models. With standard confocal microscopy, 12× 3D-ExM achieves a lateral resolution of <30 nm, enabling the visualization of nanoscale structures, including chromosomes, kinetochores, nuclear pore complexes, and Epstein-Barr virus particles. These results demonstrate that 3D-ExM provides cost-effective and user-friendly super-resolution microscopy, making it highly suitable for a wide range of cell biology research, including studies on cellular and chromatin architectures.

A study on the macro and micro mechanisms of cotton seedling growth regulation by high-voltage electrostatic field and optimization of system parameters

Addressing the issues of inefficiency and severe environmental pollution associated with artificial and chemical methods in cotton growth regulation, this study introduces the high-voltage electrostatic field environmental control technology. It delves into the technology’s macro- and microscopic impacts on cotton seedling growth and optimizes its operational parameters. At the macro level, the study examines the influence of adjusting the output voltage of the high-voltage electrostatic generator, the distance between the upper pole plate and the cotton leaf, and the action time of the electric field on seedling features above (plant height, ground diameter, and leaf area) and below ground (fresh weight and dry weight of roots). Subsequently, utilizing an orthogonal experimental design, the optimal parameters are identified: output voltage of 15.93 kV, a distance of 10.71 cm between the pole plate and cotton leaf, and an action time of 39.23 s, resulting in the most favorable overall growth condition. At the micro level, conductivity meters and transmission electron microscopy techniques are employed to investigate leaf electrical conductivity and ultrastructure changes under a high-voltage electrostatic field. Results indicate a slight conductivity increase under moderate conditions (e.g., 18 kV-8 cm), signifying healthy cell membranes. Conversely, extreme conditions (e.g., 18 kV-2 cm or 36 kV-8 cm) cause marked conductivity spikes, pointing to cellular damage. Transmission electron microscopy observations reinforce this, with intact membranes under optimal conditions but disintegration and degradation under adverse ones. In conclusion, this study unravels the internal mechanisms of high-voltage electrostatic field regulation on cotton seedling growth from macro- to micro-scales, validating its feasibility and effectiveness. This breakthrough not only pioneers a novel approach for cash crop seedling growth control but also lays a scientific foundation for refining and advancing cotton cultivation techniques, thereby advancing agricultural modernization and sustainable development goals.

Development and Validation of Particle Size Measurement for Mesalamine Nanocrystals Using Dynamic Light Scattering and Microscopic Techniques

Development and Validation of Particle Size Measurement for Mesalamine Nanocrystals Using Dynamic Light Scattering and Microscopic Techniques

Influence of radio-frequency magnetron sputtering power on electrical characteristics and positive bias stress stability of indium tin zinc oxide thin-film transistors

Abstract As the pursuit of high-quality display panels intensifies, the importance of high-performance thin-film transistors (TFTs) becomes increasingly prominent. Indium tin zinc oxide (ITZO) TFTs, as one of the promising directions for high-performance metal oxide TFTs, impose high demands on their performance and reliability. In this study, the performance and stability of ITZO TFTs fabricated under different radio-frequency magnetron sputtering power conditions were systematically tested and investigated. After sputtering power optimization, the field effect mobility of ITZO TFTs reaches 29.68 cm²/V·s, with a steep sub-threshold swing of 0.17 V/decade, near-zero threshold voltage, and good stability. Using atomic force microscopy and X-ray photoelectron spectroscopy characterization techniques, the thin films were analyzed to elucidate the relationship between sputtering power variations and oxygen vacancies.

Design and synthesis of PDSPTCF as an influential Brønsted-Lewis acidic catalyst for the producing benzo[a]benzo[6,7]chromeno[2,3-c]phenazines

Initially, 4,4'-(1,4-phenylene)di(sulfonic)pyridinium tetrachloroferrate (PDSPTCF) as a novel organic–inorganic hybrid salt was synthesized and identified by elemental mapping, energy-dispersive X-ray spectroscopy, inductively coupled plasma atomic emission spectrometer, Raman spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, vibrating-sample magnetometry, and thermal gravimetric (TG) techniques. Then, the catalytic performance of this hybrid salt was assessed for the producing benzo[a]benzo[6,7]chromeno[2,3-c]phenazine derivatives via one-pot multicomponent domino reaction (MDR) of benzene-1,2-diamine, 2-hydroxynaphthalene-1,4-dione and aldehydes under optimal conditions (70 °C, solvent-free, 5 mol% PDSPTCF) in short reaction times and high yields. Highly efficacy of the PDSPTCF for the production of benzo[a]pyrano[2,3-c]phenazines can be assigned to the synergistic effect of Lewis and Brønsted acids, and having two positions of each acid (i.e., FeCl4ˉ and –SO3H). In addition, this catalyst showed good reproducibility with six cycles of recycling.

Surface Modification of Anodized Titanium Surfaces with Chitosan/ε-Polylysine Coating, Aiming for an Improved Bioactivity, Biocompatibility, and Anti-Bacterial Properties for Orthopedic Applications

The increasidng demand for implants due to the aging populations highlights the necessity for applying highly functional coatings on the surface of implants. This study investigates the implications of applying a chitosan/polylysine composite coating on anodized titanium surfaces, aiming for improved biocompatibility, bioactivity, and anti-bacterial properties. Titanium substrates were anodized at 40 volts for a duration of two hours, followed by dip coating with the chitosan/polylysine composite. Fourier-transform infrared (FTIR) analysis was employed to characterize the polymer structure, while field emission scanning electron microscopy (FESEM) and energy-dispersive X-ray spectroscopy (EDS) techniques were utilized to evaluate nanotube morphology and the coating structure. Results showed that samples containing 1.5% polylysine exhibited noticeable anti-bacterial properties and cell viability above fifty percent. Subsequent immersion in simulated body fluid (SBF) for a duration of two weeks revealed the formation of apatite crystals on the coated samples, indicating that the samples are bioactive. Furthermore, polylysine contributed to enhanced resistance against degradation in phosphate-buffered saline (PBS) solution. Overall, the chitosan/polylysine composite coating exhibited promising mechanical and biomedical characteristics, suggesting its potential for applications in orthopedic implants.

Retinal Neurovascular Impairment in Full-Course Diabetic Retinopathy: The Guangdong Diabetic Retinopathy Multiple-Omics Study.

The purpose of this study was to explore the succession of the central and peripheral neurovascular and microstructural impairments in patients with full-course diabetic retinopathy (DR), consisting of preclinical DR, nonproliferative DR (NPDR), and proliferative DR (PDR). Our analysis included 81 participants (including 23 healthy controls, 23 with preclinical DR [diabetes without retinopathy], 13 with NPDR, and 22 with PDR) from the Guangdong Diabetic Retinopathy Multiple Omics Study. Retinal structure and function were evaluated and quantified using ultra-widefield swept-source optical coherence tomography angiography (UWF-SS-OCTA), electroretinography (ERG), and adaptive optics scanning laser ophthalmoscopy (AOSLO). Correlation analysis was conducted to explore the relationship between structural parameters and functional parameters. In the preclinical DR group, decreased amplitude in the DR assessment protocol were observed (P = 0.003), with no changes in structure and photoreceptor cells (all P > 0.05). In the NPDR group, photoreceptor cells were impaired (all P < 0.05) with delayed implicit time in the International Society for Clinical Electrophysiology of Vision (ISCEV) Photopic flicker protocol, increased macular and inner nuclear layer thickness, and decreased vessel density and perfusion area of the deep capillary plexus (all P < 0.05). In the PDR group, delayed implicit time and decreased amplitude in the ISCEV Photopic flicker and photopic negative response (PhNR) protocol, and neurovascular impairments were observed (all P < 0.05). Correlation analysis demonstrated a significant correlation between functional parameters and various structural indicators (all P < 0.05). The cone pathway function began to decline in preclinical DR and distinct photoreceptor cell disorders were observed in NPDR. Notably, instruments with a wider field of view or more detailed microscopic techniques will provide enhanced neurovascular imaging, offering fresh insights into full-course DR.

Approximating Nucleation Rates of Glass Ceramics Using In-Situ X-ray Diffraction

Glass ceramics are ideal for applications ranging from the culinary to defense industries. The properties of glass ceramics are a strong function of their microstructure, which in turn is controlled by constitutive nucleation and growth treatments. Nucleation has been extensively studied but remains an experimental and theoretical challenge. Traditional isothermal methods for measuring nucleation rates require time-consuming measurements and careful statistics, leading to only a few material systems with nucleation data available, approximately one-hundred glass systems were studied in half a century. To overcome these challenges, we present a new non-isothermal technique utilizing in-situ X-Ray Diffraction (XRD) with data analyzed through a modified Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation. Three homogenous nucleated glass systems were analyzed: Li2O•2SiO2 (lithium disilicate), Na2O•2CaO•3SiO2 (combeite), and Li2Oׅ•2B2O3 (lithium diborate). This method utilizes crystallized fractions through XRD, allowing resolution far beyond microscopy techniques. It was thus possible to compare the evolution of the crystallized volume fractions by X-ray diffraction with optical microscopy from literature. This method was successful in reproducing the experimental nucleation curve from the temporal development of the number density and crystal size within four orders of magnitude, while also achieving the correct peak position, leading to a new method to rapidly approximate the nucleation rate of complex glass-ceramics.

Effects of adding copper to bismuth titanate for photocatalytic hydrogen production

In this work, pure and copper-doped bismuth titanate perovskites were synthesized using the modified amorphous citrate method to evaluate the influence of the dopant on the material's structure and its efficiency as a catalyst. X-ray diffraction method has been employed for the analysis of the crystal structure while scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques were used to examine the material's morphology. Electron dispersion spectroscopy (EDS) was also employed to confirm the doping of the material. The doped material exhibited a bandgap within the visible region calculated using the Tauc plot from UV-Vis diffuse reflectance spectroscopy. The dopant influenced the emergence of secondary bandgaps with considerably lower values than the pure materials, directly impacting the photocatalytic performance of hydrogen gas (H2) production. The highest H2 gas production occurred in the doped and more crystalline sample. Comparing these results with other studies, it can be concluded that copper is a metal with great potential as a dopant for the development of bismuth titanate-based catalysts.

Mechanical strength and mineralogical properties of fiber-reinforced geopolymer composites with multi-walled carbon nanotubes

In this study, polyethylene (PE) fibers and functionalized multi-walled carbon nanotubes (f-MWCNTs) were used to increase the mechanical and microstructural behavior of ground granulated blast furnace slag (GGBS)-incorporated engineered geopolymer composites (EGC) i.e., GGBS-EGC. The efficacy of different compositions, specifically 0.10 % f-MWCNTs and 0.15 % PE fibers, was confirmed by means of mechanical tests. The mix was characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) techniques. The results showed that the optimal mix of 0.15 % PE fibers, 0.10 % f-MWCNTs, and 20 % GGBS achieves a compressive strength of 38.03 MPa. While f-MWCNTs enhance strength by filling micropores, excessive amounts can hinder performance. The strong bonding improves structural integrity and ductility, with significant changes observed in crystalline structure and bonding.

Development of rare earth doped SiO2/rGO from rice husk for antioxidant, photocatalysis, electrochemical and sensor studies

The present work determines the synthesis of cerium loaded silicon dioxide (Ce-SiO2/rGO) nanocomposite by using reflux method. The Ce-SiO2/rGO was confirmed by using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive (EDAX) techniques. In photodecomposition investigation, Rose Bengal (RB) dye was degraded efficiently using Ce-SiO2/rGO nanocomposite (95 %) at 150 min with follows first order kinetics. The antioxidant property against 2,2-diphenyl-1-picrylhydrazyl (DPPH) was found to be 98 % performance with IC50 value of 488.35 mg/mL. The super capacitance value of Ce-SiO2/rGO was increased compared to that of rGO, SiO2 and SiO2/rGO respectively. The electrochemical reversibility (EO−ER) and diffusion coefficient (D) values were determined using 1 M KCl by cyclic voltammetry method. Ce-SiO2/rGO nanocomposite was used as an electrochemical sensor to detect bee pollen and cow urine. The produced material has superior dye purification, redox behavior, bio-molecule detection, and antioxidative capabilities.

Advancing solar wastewater treatment: A photocatalytic process via green ZnO/g-C3N4 coatings and concentrated sunlight – Comprehensive insights into ciprofloxacin antibiotic inactivation

In this study, a sustainable method employing concentrated sunlight to achieve environmental remediation of wastewater, contaminated by Ciprofloxacin antibiotic (CIP), is thoroughly investigated. A green ZnO/g-C3N4 nanocomposite (NC) is used as a photocatalyst coating on glass to investigate the inactivation of CIP in water, in a flow-reactor configuration at small-prototype scale (10 liters/h, catalyst area 187.5 cm2). ZnO/g-C3N4 NC coatings were obtained by an in-situ thermal condensation process coupled with a green synthesis protocol and deposited on glass, via a simple drop casting method. Morphological and structural analyses of synthesized composites were performed with Fourier-Transform Infrared (FTIR) Spectroscopy, Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray (EDX) and X-ray diffraction (XRD) techniques, while optical properties were studied with Diffuse Reflectance Spectroscopy (DRS). The degradation of CIP was first tested at a lab scale under simulated sunlight and then studied under sunlight in a parabolic trough concentrator (PTC). Suitable degradation of CIP (100%) was observed at 210 min via High-Performance Liquid Chromatography (HPLC) and the by-products were determined by Liquid Chromatography-Mass Spectroscopy (LC–MS). Microbiological tests revealed the absence of antibacterial activity in CIP water treated with ZnO/g-C3N4 NC photocatalyst against Staphylococcus aureus, Pseudomonas aeruginosa, and Priestia megaterium. Our results directly demonstrate the effective inactivation of CIP with a process designed for sustainability both in terms of energy input (solar) and scalability of materials. Also, the small-prototype scale of this investigation provides insights into the challenges arising from the perspective scale-up to an industrial application, aimed at antibiotics inactivation in wastewater and thus helping to prevent the spread of antimicrobial resistance (AMR).