Fluorescence Spectroscopy Research Articles

Luminescent Dansyl-Calix[5]arene for the Recognition of Biogenic Amines

: A luminescent calix[5]arene with a covalently linked dansyl chromophore substituent has been successfully used, both in solution and in the gas phase (ESI-MS), for the recognition of biogenic amines that contain linear alkylammonium structural unit. Binding constant values, determined by fluorescence spectroscopy, revealed a greater affinity for cadaverine, spermidine, and L-lysine, in which the terminal ammonium group allows for additional stabilizing interactions with the dansyl moiety.

“Green mathematical approaches in fluorescence spectroscopy for quality control and clinical studies”

In the past decade, significant advancements have been made in mathematical spectral approaches for estimating binary and ternary drug combinations in raw materials and dosage forms. These approaches established on mathematical spectral manipulations of mixture analytes, without the need for separation techniques.The idea of using mathematical spectral approaches in fluorescence spectroscopy was resolving analytical issues and reach to biological concentrations thus, Ratio subtraction (RD) and ratio subtraction coupled with constant multiplication (RS-CM) have been proposed in fluorescence spectroscopy to evaluate the content uniformity of Flunarizine dihydrochloride (FLZ) and Propranolol hydrochloride (PRO) combination in raw materials, tablets, and spiked biological fluids (blood-urine). These approaches have demonstrated the ability to overcome the quantitative analytical challenges posed by the high native fluorescence intensity of the major component (PRO) at λex = 286/λem = 341 nm and the low native fluorescence intensity of the minor component (FLZ) at λex = 254/λem = 311 nm. The linearity range for (PRO) was found to be 25–500 ng/mL, and for (FLZ), it was 50–500 ng/mL. However, the spectrum addition technique was required to estimate (FLZ) in mixtures with concentrations less than 300 ng/mL.The overall validity of the proposed approaches was confirmed through adherence to ICH guidelines, and no statistical variation was observed in comparison to official studies. Additionally, the greenness and whiteness of the proposed approaches were evaluated using the Analytical greenness metric (AGREE), Green Solvents Selecting Tool (GSST), and Red-Green-Blue (RGB) algorithm.

Natural photosensitizer extraction from Delonix regia flowers for future photosensor for DSSCs applications

This study explores the utilization of Delonix regia (DR) (Gulmohar flower) as a natural photosensitizer in the fabrication of self-powered photosensors via dye-sensitized solar cells (DSSCs). Various photoanodes, including ZnO, ZnO/TiO2, and ZnO/TiO2/Nb2O5, were investigated for their performance enhancement in DR-based photosensors. The photoanodes were fabricated using different deposition methods sensitized with DR photosensitizer and characterized through X-ray diffraction analysis, Field emission scanning electron microscopy (FE-SEM), UV–visible, Fluorescence spectroscopy, and Fourier transform infrared spectroscopy (FTIR) analysis. The absorbance spectrum results indicate improved photosensitizer adsorption in visible light for the ZnO/TiO2/Nb2O5/DR photoanode compared to other configurations. The scanning electron microscopy (SEM) cross-section image of ZnO/TiO2/Nb2O5 confirmed the formation of a multilayer photoanode. Chronoamperometry experiments were conducted to evaluate the photo sensing behavior, focusing on sensitivity, photoresponsivity, specific detectivity, and quantum efficiency within the solar spectrum range. Among the devices, ZnO/TiO2/Nb2O5 exhibited the highest photoresponsivity (1.2 × 10 −3 A/W) and photodetectivity (26.78 × 104 Jones), demonstrating promising advancements in DR-sensitized photosensors. This research highlights the exceptional performance of DR-sensitized photoanodes, particularly ZnO/TiO2/Nb2O5, in advancing the capabilities of photo-sensing devices. The investigated configuration exhibited a rapid response speed of 723 ms and a remarkable sensitivity of 89.87% in detecting photo signals. These findings emphasize the potential of DR photosensitizers to enhance photo-sensing activities, with significant implications for diverse applications in photodetection. By leveraging the unique properties of DR, particularly its incorporation into ZnO/TiO2/Nb2O5, this study underscores the promising prospects for developing efficient self-powered photosensors. The insights gleaned from this work pave the way for further exploration and optimization in organic photosensors.

Characterisation and analysis of soil properties and trace elements in agricultural soils of Rabat-Sale-Kenitra, Morocco: focus on stable strontium and caesium

ABSTRACT This study explores strontium (Sr) and caesium (Cs) dynamics in Moroccan agricultural soils, focusing on contaminant impacts and soil properties. Soil samples from El Koudia, Merchouch, and El Guich exhibit different textures: clayey (Merchouch), sandy clay loam (El Koudia), and sandy (El Guich). Chemical analysis shows consistent pH, with %CaCO3 at 1%, 4%, and 6%, and organic matter content at 4.5%, 1.1%, and 3.3% in Merchouch, El Guich, and El Koudia, respectively. Cation exchange capacity (CEC) and levels of Ca, K, Na, Mn, and Fe were measured. X-ray diffraction (XRD) identified quartz as the main mineral, with site-specific variations. X-ray fluorescence spectrometry (XRF) indicated consistent Cr, Ni, Cu, Zn, As, and Pb levels, and Rb varied significantly. Sr concentrations were 0.17 ppm in El Koudia and Merchouch, and 0.32 ppm in El Guich. Cs was undetected. This research highlights complex soil properties, elemental composition, and contaminant distribution in agricultural soils.

The Influence of Pyrolysis Temperature and Feedstocks on the Characteristics of Biochar-Derived Dissolved Organic Matter: A Systematic Assessment

Biochar is a carbon-rich product obtained by pyrolyzing biomass under oxygen-limited conditions and has a wide range of potential for environmental applications. In particular, dissolved organic matter (DOM) released from biochar has an important impact on the fate of pollutants. The study aimed to systematically assess how varying pyrolysis temperatures and biomass feedstocks influence the characteristics of biochar-derived DOM. DOM samples were comprehensively characterized utilizing UV-vis spectroscopy and excitation–emission matrix (EEM) fluorescence spectroscopy, coupled with parallel factor (PARAFAC) analysis. The study discovered that pyrolysis temperature significantly affects DOM characteristics more than feedstock type. An increase in pyrolysis temperature correlated with a notable decrease in dissolved organic carbon content, aromaticity, and fluorescence intensity, alongside a marked increase in pH and hydrophilicity. PARAFAC analysis identified three distinct DOM components: two humic-like substances (C1 and C2) and one protein-like substance (C3). The proportion of protein-like substances increased with higher pyrolysis temperatures, while the humic-like substances’ proportion declined. The compositional shifts in DOM with pyrolysis temperature may significantly influence its environmental behavior and functionality. Further research is necessary to explore the long-term environmental impact and potential applications of biochar-derived DOM.

Enhanced Removal of Refractory Organic Compounds from Coking Wastewater Using Polyaluminum Chloride with Coagulant Aids

This study explores the enhanced removal of refractory organic compounds from coking wastewater using polyaluminum chloride (PACl) with two different basicity levels (0.5 and 2.5), in combination with coagulant aids such as cationic polyacrylamide (CPAM) and iron ions. The results demonstrated that both PACl formulations significantly outperformed commercial PACl in terms of COD and color removal, with PACl at the basicity of 2.5 achieving slightly higher efficiency than PACl at the basicity of 0.5. The improved performance was attributed to the higher content of polymeric aluminum species, enhancing charge neutralization and bridging adsorption. The addition of coagulant aids further improved the performance, with PACl at the basicity of 2.5 combined with iron ions achieving the highest COD (48.41%) and color removal (80.77%), due to sweep coagulation and complexation. Organic composition analysis using gas chromatography–mass spectrometry (GC-MS), three-dimensional excitation–emission matrix (3D-EEM) fluorescence spectroscopy, and ultraviolet (UV) spectroscopy indicated that PACl combined with iron ions was the most effective in removing polycyclic aromatic hydrocarbons (PAHs) and nitrogen-, oxygen-, and sulfur-containing heterocyclic compounds. Additionally, a floc analysis showed that the flocs formed with iron ions were more compact and had better settleability compared to those formed with CPAM, further contributing to the improved coagulation efficiency. These results highlight the importance of optimizing the PACl basicity and coagulant aid selection for the enhanced removal of refractory organic compounds from coking wastewater, offering a promising strategy for advanced wastewater treatment.

Metal complexes containing vitamin B6-based scaffold as potential DNA/BSA-binding agents inducing apoptosis in hepatocarcinoma (HepG2) cells.

A ligand (HL) was synthesized from the pyridoxal hydrochloride (vitamin B6 form) and 1-(2-Aminoethyl)piperidine in one single step. The metal complexes [Zn(L)(Bpy)]NO3 (1), [Cu(L)(Bpy)]NO3 (2), and [Co(L)(Bpy)]NO3 (3) were prepared by tethering HL and 2,2'-bipyridine. The synthesized HL and metal complexes 1-3 were thoroughly characterized using spectroscopic techniques such as 1H NMR, 13C NMR, FTIR, EI-MS, molar conductance, and magnetic moment, in addition to CHN elemental analysis. The geometry of complexes was square pyramidal around the metal ions {Zn(II), Cu(II), and Co(II)}. The interaction of ligand and metal complexes with DNA and BSA macromolecules was accomplished by UV-Vis absorption and fluorescence spectroscopy in vitro. The hyperchromism in band at 303-325 with no shift supports the groove binding with some partial intercalation in grooves. Similarly, in BSA-binding studies, complex 2 shows greater binding potential in the hydrophobic core probably near the Trp-212 in the subdomain IIA. Furthermore, complex 2 shows excellent cytotoxicity on HepG2 cancer cells with IC50 = 25.0 ± 0.45µM. The detailed analysis by cell-cycle studies shows cell arrest at the G2/M phase. The type of cell death was authenticated by an annexin V-FTIC dual staining experiment that reveals maximum death by apoptosis together with non-specific necrosis.

Synergistic effects of β-Cyclodextrin derivative inclusion complexes with favipiravir to enhance solubility and antiviral efficacy against Herpes Simplex virus type 1 (HSV-1)

In this study, the formation of β-cyclodextrin derivatives (β-Cyclodextrin; β-CD, Hydroxypropyl-β-Cyclodextrin; Hβ-CD, and Sulfobutylether-β-Cyclodextrin; Sβ-CD) inclusion complexes with favipiravir (FPR) was confirmed using various spectroscopic and analytical techniques. These complexes were shown to enhance FPR solubility and antiviral activity against herpes simplex virus type 1 (HSV-1). UV–visible and fluorescence spectroscopy revealed a continuous increase in FPR absorbance and fluorescence intensity with increasing β-CD concentrations, indicating the successful formation of 1:1 inclusion complexes. The prepared β-CD solid complexes were characterized using FTIR, XRD, FESEM, and TGA-DSC, which highlighted significant surface properties, morphological changes, and improved thermal stability. Phase solubility studies demonstrated enhanced FPR solubility in the presence of the β-CDs, with stability constants (Ks) following the order: Hβ-CD (694.8 M−1) > Sβ-CD (418.4 M−1) > β-CD (364.3 M−1). In-vitro release studies showed that the Hβ-CD complex achieved a higher cumulative release of 90.16 ± 1.94 % over 90 min compared to free FPR (25.32 ± 0.29 %), attributed to its greater solubility. Molecular docking provided insights into the interaction mechanisms, revealing higher binding affinities and stability for FPR with β-CD. In-vitro antiviral assays against HSV-1 demonstrated significant viral titer reductions for free FPR with β-CDs, with Hβ-CD outperforming others due to its rapid release profile after 96 h of incubation, confirming its potential for improved antiviral formulations. The cytotoxic effects of FPR and its β-CDs inclusion complexes were evaluated on Vero cells using an MTT assay over 96 h, showing reduced cytotoxicity for the inclusion complexes compared to free FPR. Additionally, cellular uptake studies revealed that β-CDs inclusion complexes conjugated with DAPI and FITC exhibited greater intensity within Vero cells compared to free FPR.

Reaction Time Induced a Two-Step Dissolution and Recrystallization Structural Transformation with Three Eu Metal-Organic Frameworks: Crystal Structures and Multiresponsive Fluorescence Detection.

Under solvothermal conditions, three 3D lanthanide metal-organic frameworks (Ln-MOFs): [Eu(H2DHTA)1.5(DMF)2]·DMF (1), [Eu(H2DHTA)0.5(DHTA)0.5(DMF)(H2O)]·2H2O (2), and Eu(HCOO)3 (3) (H4DHTA = 2,5-dihydroxyterephthalic acid) have been synthesized by different reaction times. Interestingly, induced by reaction time, compounds 1-3 underwent a two-step dissolution and recrystallization structural transformation (DRST) reaction. Investigations on the DRST processes were carried out, and the transformation pathway was deduced, which was verified by XRD analyses. Notably, compound 2 demonstrates pronounced luminescence as well as high stability in water and other organic solvents. The fluorescent detection of furan antibiotics can serve as turn-off effects, and glutamic acid (Glu), aspartic acid (Asp), and riboflavin (VB2) can serve as the turn-on effect. To explain the enhancing and quenching mechanisms, XRD, UV-visible absorption spectroscopy, electrochemistry, IR spectra, theoretical calculation, fluorescence lifetimes, and XPS were discussed. Additionally, MOF-coated test strips were utilized to detect these analytes, exhibiting excellent agreement with fluorescence spectroscopy. This work provides an example for more effective designs to employ Ln-MOFs as multiresponsive fluorescent sensors for detection of environmental pollutants in aqueous solution.

Linear Source Apportionment Using Generalized Least Squares

Motivated by applications to water quality monitoring using fluorescence spectroscopy, we develop the source apportionment model for high dimensional profiles of dissolved organic matter (DOM). We describe simple methods to estimate the parameters of a linear source apportionment model, and show how the estimates are related to those of ordinary and generalized least squares. Using this least squares framework, we analyze the variability of the estimates, and we propose predictors for missing elements of a DOM profile. We demonstrate the practical utility of our results on fluorescence spectroscopy data collected from the Neuse River in North Carolina.

Evaluation of alteration in the geothermal province west of Cappadocia, Türkiye: Mineralogical, petrographical, geochemical, and remote sensing data

Abstract This study determines the mineralogical, petrographical, and geochemical properties of the rocks outcropping in geothermal areas west of the Cappadocia geothermal region. These areas include Ziga, Narlıgöl, Belisırma, Ilısu, and Sivrihisar. The study reveals their hydrothermal alteration characteristics. Also, the study aims to determine the zones of hydrothermal alterations using remote sensing. Rock samples from geothermal areas were performed using optical microscopy, X-ray diffraction (XRD), scanning electron microscopy, X-ray fluorescence spectroscopy, and inductively coupled plasma–mass spectrometry techniques for the determination of mineralogical assemblages and major, trace and REE's analyses. Rock samples, determined as ignimbrites and tuff, exhibit intensive alterations. XRD analysis determined the association of alteration minerals. The dominant clay minerals were kaolinite, montmorillonite, and illite. The analyses and mineral associations are compatible with argillic, mid-argillic alteration, and silicification zones. Alteration zones were identified by classifying the ASTER satellite images of kaolinite, illite, and montmorillonite using the CROSTA technique. The alteration zones observed in this study are close to existing geothermal areas. In addition, different regions with these alterations have been identified within the study area and are expected to be a valuable reference for future geothermal exploration.

Molecular–level insights into the synergistic activation of peracetic acid by ultraviolet and ferrous ions for the degradation of sedimentation sludge water in drinking water treatment plants based on Fourier transform-ion cyclotron resonance mass spectrometry

Sedimentation sludge water (SSW) from sedimentation tanks in drinking water treatment plants contains significant amounts of dissolved organic matter (DOM) and precursors of disinfection byproducts, raising increasing concerns about the safety of finished water following SSW recycling. This study explores the alterations in bulk properties and molecular characteristics of DOM in SSW treated with ultraviolet (UV)/ferrous ions (Fe2+) and peracetic acid (PAA) using fluorescence spectroscopy and Fourier transform ion cyclotron resonance mass spectrometry (FT–ICR MS). The primary reactive species, hydroxyl radicals (·OH) and acylperoxy radicals (CH3C(O)OO·) achieved degradation rates of up to 82.0%, eliminating 84.5% of total fluorescent components and reducing molecular intensity and apparent molecular count by 90.9% and 69.8%, respectively. This treatment significantly reduced the aromaticity of DOM, leading to the formation of more oxidized and stable compounds. Reaction mechanisms indicate that ·OH and CH3C(O)OO· primarily facilitate oxygen addition and dehydrogenation, while CH3C(O)OO· promotes decarboxylation through weak electron transfer processes. The treatment preferentially removes complex DOM containing nitrogen and sulfur heteroatoms, which are key precursors of disinfection byproducts. These findings enhance our understanding of DOM transformations during UV/Fe2+/PAA treatment and provide valuable insights into the safe recycling of SSW.

Investigation of the crystal structure, spectral properties, and interactions of N-(R-nitrophenylsulfonamido)benzoic acids with human serum albumin

This study introduced the synthesis of two novel compounds in the N-(R-nitrophenylsulfonamido)benzoic acids (NO2-SBA), designated as HL6 and HL8. Detailed structural information for HL6 and HL8 was acquired through the employment of various characterization techniques such as single-crystal and powder X-ray diffraction, FT-IR spectroscopy, 1H and 13C NMR spectroscopy, and elemental analysis. X-ray diffraction and Hirshfield surface analysis provides a comparative analysis of hydrogen bonding in HL6·H2O and HL8, revealing significant differences in their interaction patterns and resulting crystal structures. Although both molecules possess the same number of hydrogen bond donors and acceptors, the nature of these interactions and their orientations lead to distinct packing arrangements. In HL6·H₂O, the presence of water molecules introduces additional hydrogen bonding possibilities, which are absent in HL8, significantly affecting the overall structure. Additionally, interactions of all nine compounds in the NO2-SBA series [categorized as o-ABA: HL1–HL3, m-ABA: HL4–HL6, and p-ABA: HL7–HL9] with human serum albumin (HSA) were investigated to understand how structural characteristics influence binding mechanisms and affinity. Fluorescence spectroscopy was employed to further examine these interactions, providing a better understanding of their pharmacological properties. The compounds exhibited moderate affinity to HSA, with the o-ABA series displaying a binding constant (Kb) ten times stronger than the other series, underscoring the significant role of the N,R groups in binding interactions.

Interaction between reacetylated chitosan and albumin in alcalescent media

Interaction of chitosan and its derivatives with proteins of animal blood at blood pH relevant conditions is of a particular interest for construction of antimicrobial chitosan/protein-based drug delivery systems. In this work, the interaction of a series of N-reacetylated oligochitosans (RA-CHI) having Mw of 10–12 kDa and differing in the degree of acetylation (DA 19, 24, and 40 %) with bovine serum albumin (BSA) in alkalescent media is described in first. It is shown that RA-CHI forms soluble complexes with BSA in solutions with pH 7.4 and a low ionic strength. Light scattering study shows that soluble RA-CHI complexes have spherical form with the radius of about 100 nm. Circular dichroism, fluorescent spectroscopy, and micro-IR spectroscopy studies show that the secondary structure of BSA in soluble complexes remain intact. Isothermal titration calorimetry of RA-CHI with DA 24 % and BSA mixing in the buffers with different ionization heats reveals a significant contribution of electrostatic forces to the binding process and an additional ionization of chitosan due to the proton transfer from the buffer substance. An increase of ionic strength to the blood relevant value 0.15 M suppresses the binding. It is shown that application of RA-CHI with higher DA value leads to a decrease in the affinity of RA-CHI to BSA and an alteration of the interaction mechanism. The finding opens an opportunity to the application of N-reacetylated chitosan derivatives in the complex systems compatible with blood plasma proteins.

Pyrene monomer-excimer dynamics to reveal molecular organization in mesoporous hybrid silica films.

Self-assembly and characteristics of hybrid mesoporous silica film templates remain a subject of inquiry. The short time scale of the inorganic condensation and formation of micelles makes our understanding of this process insufficient. To provide an insight into the evaporation-induced self-assembly of such films, we synthesized an efficient molecular probe of the triethoxysilane precursor bearing a pyrene derivative. The probe was introduced into the porous film at the synthesis stage through the sol-gel co-condensation method. At different synthesis stages, the emission of pyrene moieties was measured by fluorescence spectroscopy, revealing the placement of probes within the film. We also report dynamic excimer formation upon template removal. Moreover, we evaluate the influence of several parameters on the pyrene excimer formation phenomenon. The pore geometry, probe concentration, and the presence of another organosilane precursor are investigated in this work.

Ritual use, consumption, and depositional practices at Agriomernos Cave, Northwestern Samos (Greece): A ceramic analytical approach

This study utilises pottery as a proxy to identify patterns of use and consumption, as well as depositional strategies at Agriomernos, a recently discovered cave site on Samos Island (Greece). This discovery challenges our understanding of human–landscape interaction within a marginal region across two distinct prehistoric chronological episodes. As part of a broader research project, this paper presents the results from an integrated, multiscale analysis of pottery through morpho-stylistic and macroscopic examination, thin section petrography, and wavelength dispersive X–ray fluorescence spectroscopy (WD-XRF). The analysis has revealed a compositionally diverse ceramic assemblage that represents a range of different raw material sources on the island and, by extension, different groups of people. The identification of off-island imports adds new evidence to the reconstruction of Aegean connectivity patterns. Agriomernos Cave constitutes a key archaeological site within an area previously unexplored, offering a unique opportunity to investigate ancient mobility, landscape sacrality, and ritual performances manifested through periodical and repeated acts of deposition.

A comparative study into the effect of spent coffee powder and ash on improving the mechanical properties of bitumen

Nowadays, waste and renewable materials are used to modify bitumen and asphalt, reduce costs, decrease the use of natural resources, and maintain ecological balance, and have thus received much attention. This study aimed to improve the rheological properties of bitumen and reduce spent coffee grounds' (SCG) waste by partially replacing it with SCG powder and ash. SCG powder and ash were added in percentages of 0, 1, 3, 5, and 8 wt percent of bitumen to check the properties of control and modified bitumens. Microstructural properties were evaluated by Fourier transform infrared spectroscopy, thermal gravimetric analysis, X-ray fluorescence spectroscopy (XRF), and scanning electron microscopy (SEM). Penetration, softening point, and ductility tests were performed to check the physical properties of bitumens, along with the storage stability test. Rheological tests (viscosity, bending beam rheometer (BBR), dynamic shear rheometer (DSR), multiple stress creep and recovery (MSCR), and linear amplitude sweep (LAS) were also carried out. According to the BBR results, adding SCG powder up to −12 °C and adding SCG ash up to −6 °C increased the resistance to low temperatures. Based on DSR and MSCR results, SCG, either in the form of ash or powder, increased the resistance to rutting, and adding SCG ash improved the high temperature performance of bitumen by 1 grade. At 64 °C, adding 8 % of SCG powder increased the rutting resistance by 43 %, and adding SCG ash raised the rutting resistance by about 113 %. LAS results also showed that SCG ash outperforms SCG powder in fatigue. Although both SCG powder and ash performed well in high, moderate, and low temperatures, SCG powder performed better in cold regions, and SCG ash performed better in regions with temperate and tropical climates.

Nanoscale elemental and morphological imaging of nitrogen-fixing cyanobacteria.

Nitrogen-fixing cyanobacteria bind atmospheric nitrogen and carbon dioxide using sunlight. This experimental study focused on a laboratory-based model system, Anabaena sp., in nitrogen-depleted culture. When combined nitrogen is scarce, the filamentous procaryotes reconcile photosynthesis and nitrogen fixation by cellular differentiation into heterocysts. To better understand the influence of micronutrients on cellular function, 2D and 3D synchrotron X-ray fluorescence mappings were acquired from whole biological cells in their frozen-hydrated state at the Bionanoprobe, Advanced Photon Source. To study elemental homeostasis within these chain-like organisms, biologically relevant elements were mapped using X-ray fluorescence spectroscopy and energy-dispersive X-ray microanalysis. Higher levels of cytosolic K+, Ca2+, and Fe2+ were measured in the heterocyst than in adjacent vegetative cells, supporting the notion of elevated micronutrient demand. P-rich clusters, identified as polyphosphate bodies involved in nutrient storage, metal detoxification and osmotic regulation, were consistently co-localized with K+ and occasionally sequestered Mg2+, Ca2+, Fe2+, and Mn2+ ions. Machine-learning based k-mean clustering revealed that P/K clusters were associated with either Fe or Ca, with Fe and Ca clusters also occurring individually. In accordance with XRF nanotomography, distinct P/K-containing clusters close to the cellular envelope were surrounded by larger Ca-rich clusters. The transition metal Fe, which is part of nitrogenase enzyme, was detected as irregular shaped clusters. The elemental composition and cellular morphology of diazotrophic Anabaena sp. was visualized by multimodal imaging using AFM, SEM, and fluorescence microscopy. This paper discusses the first experimental results obtained with a combined in-line optical and X-ray fluorescence microscope at the Bionanoprobe.

Eco-friendly natural rubber-based hydrogel loaded with nano-fertilizer as soil conditioner and improved plant growth

This study addresses the dual challenge of agricultural cost and waste management by harnessing agrarian waste to produce nano-fertilizers (NF) to enhance crop yield while mitigating environmental impacts. Recognizing the limitations of traditional hydrogels' non-biodegradability and their inability to sustain root zone moisture and nutrient levels, we developed an LNR/AAc/pectin hydrogel. This innovative hydrogel offers a viable solution that provides a consistent NF supply and improves water retention efficiently. Additionally, we utilized Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy-energy dispersive x-ray (SEM-EDX), and thermogravimetric analysis (TGA) to analyze the hydrogel's structure, stability, and form. Transmission electron microscopy (TEM) and X-ray fluorescence spectroscopy (XRF) were employed to ascertain the NF concentration. The optimization of the hydrogel's swelling and NF release was conducted through a 5-level, 2-factor Response Surface Methodology (RSM), focusing on the effects of the AAc: LNR ratio and pectin weight while maintaining constant concentrations of potassium persulfate (KPS) and MBA. Results revealed a high correlation between predicted and experimental values, with determination coefficients (R2) of 0.9982 for swelling and 0.9979 for NF release. Furthermore, the hydrogel exhibited a 96.30 % biodegradation rate after 120 days of soil burial. Our findings demonstrate the hydrogels' potential to significantly impact farming and gardening by ensuring a sustainable supply of nutrients to enhance soil moisture retention.

Synthesis and characterization of fluorescent carbon dots obtained from citrus x sinensis by an eco-friendly method

The synthesis and characterization of fluorescent carbon dots (CDs) obtained by an environmentally friendly method through carbonization, fragmentation and centrifugation of orange peel (citrus x sinensis) are reported. By thermogravimetry, 4 degradation regions associated with hemicellulose, lignin and organic matter were found. The SEM micrograph shows a rough surface morphology with flakes and granulation due to the carbonization process. X-ray diffraction (XRD) shows a hexagonal crystalline structure associated with graphitic carbon, which was confirmed by Raman scatterings, Raman spectroscopy that presented two main vibrational bands, D and G, associated with active defects in the graphitic carbon crystalline structure. The Transmission electron microscopy (TEM) micrograph showed CDs of size 33.65 ± 0.68n, and with High-Resolution TEM (HRTEM) an interplanar distance of 0.213 nm in the direction of the crystal planes (100) of graphitic carbon was obtained, which were confirmed by XRD and Raman spectroscopy. X-ray photoelectron spectroscopy revealed the relative atomic composition and identified the strongest photoelectron transitions of carbon, sp2 (286 eV) and sp3 (285 eV), in graphitic carbon. Ultraviolet–visible (UV–Vis) spectroscopy of the CDs obtained from fragmentation graphitic carbon showed a band at 205 nm associated with CC bonds π-π* of CC and n-π*, as well as two bands at 276 and 328 nm associated with bond transitions. The Fourier Transform Infrared (FTIR) spectrum showed bands associated with CHs bonds as well as CC, CN bonds of the CDs. Fluorescence spectroscopy showed three emission bands at 2.43, 2.54 and 2.87 eV. The CDs showed the emission of the characteristic blue colour.