Fluorescence Technique Research Articles

Synthesis and Properties of Covalently Linked Fluorescent Tetrads Containing Two BODIPYs and Two 3‐Pyrrolyl BODIPYs

Two covalently linked fluorescent tetrads containing two BODIPY units and two 3‐pyrrolyl BODIPY units have been synthesized over a sequence of steps starting with bis(3‐pyrrolyl BODIPY) as the key precursor. Both covalently linked tetrads 6 and 7 were confirmed by HR‐MS and characterized and studied by 1D and 2D NMR, absorption, cyclic voltammetry, steady state and time‐resolved fluorescence techniques, and also by DFT and TD‐DFT methods. The tetrad 6 exhibited one strong absorption band at 680 nm whereas the tetrad 7 showed strong absorption bands at 510 nm and 648 nm corresponding to BODIPY and 3‐pyrrolyl BODIPY units respectively and the absorption band of tetrad 6 was bathochromically shifted due to effective π‐conjugation in tetrad 6 compared to tetrad 7. The electrochemical studies revealed that tetrads exhibit only two reductions indicating their electron deficient nature. The steady state and time‐resolved fluorescence studies invoked a possibility of singlet‐singlet energy transfer from BODIPY units to 3‐pyrrolyl BODIPY units in one of the tetrads upon selective excitation of BODIPY unit. In this tetrad, the BODIPY unit acts as an energy donor whereas the 3‐pyrrolyl BODIPY unit acts as an energy acceptor. The theoretical studies were corroborated with experimental results.

Metal Contamination and Human Health Risk Assessment of Soils from Parks of Industrialized Town (Galati, Romania)

The aim of the present study was to evaluate the contamination state of the surface soil from 10 parks from Galati, Romania, and the health hazards of the soil. The soil samples, collected in each site from the playing ground and from the edge of the park, were analyzed by using combined Wavelength- (WDXRF) and Energy-Dispersive (EDXRF) X-ray fluorescence techniques. A total number of 27 chemical elements (Ag, Al, As, Ba, Ca, Cd, Cr, Co, Cu, Fe, Hg, K, Mg, Mn, Na, Ni, P, Pb, Rb, Sb, Sc, Sn, Sr, Ti, V, Zn and Zr) were quantified in the urban soils, and the results were compared to the normal and alert values from Romanian legislation for toxic trace elements, as well as with European and world average values of element concentrations. The mineralogical analyses were performed by Scanning Electron Microscopy with Energy-Dispersive X-ray Analysis (SEM-EDX) and the Attenuated Total Reflectance–Fourier Transform Infrared technique (ATR-FTIR). To assess the soil contamination and the impact on human health of the presence of potential toxic elements and heavy metals in the soil, a series of pollution and health risk indices were used. All the results indicated an unpolluted to moderately polluted soil. The soil samples collected from the edge of the parks presented higher values for the specific pollutants, which originated from heavy traffic, such as Cu, Cr, Zn and Pb. The non-carcinogenic and carcinogenic risk to children was assessed using estimated daily intake (EDI) in relation to the pathways whereby pollutants can enter the human body, such as ingestion, dermal contact, inhalation and vaporization. Using the obtained values for EDI, the hazard quotient and hazard index were determined, which strengthen the formerly issued presumption that soil pollution is moderate and, by itself, does not present any threat to children’s health.

Calcium vacancy enhanced self-reduction of Ce4+ for single-phase full-spectrum lighting and information encryption

Due to the wide and adjustable emission range, Ce3+ is an indispensable luminous center for full spectrum lighting. However, it needs to be sintered at high temperature in a reducing atmosphere, resulting in difficulty to coexisting with other multivalent activated ions (such as Eu3+, Tm3+), which greatly hinders the formation of full spectrum. In this study, a calcium vacancy enhanced self-reduction of Ce4+ is realized in CaNaSb2O6F (CNSOF) host under air atmosphere sintering, through which Ce3+, Tm3+ and Eu3+ coexisting in a single-phase full spectrum phosphor was prepared. Notably, the artificial introduction of a calcium vacancy was designed to verify this self-reduction mechanism. Moreover, the energy transfer kinetics among Tm3+, Ce3+ and Eu3+ were explored. Finally, combined with a 340 nm UV chip, a full spectrum phosphor-converted light-emitting diode (pc-LED) was fabricated, showing a broad emission range from 400 to 750 nm, Commission Internationale de I’Eclairage (CIE) of (0.3485, 0.3673), Ra of 92 and correlated color temperature (CCT) of 4933 K. Utilizing the variation in emission colors of this phosphor under different UV wavelengths, a dual encryption method combining point character code and fluorescent encryption technique is proposed. This work provides an effective path for Ce4+ self-reduction to apply in full spectrum pc-LED and information encryption.

Recent Developments of Hybrid Fluorescence Techniques: Advances in Amyloid Detection Methods.

Amyloid fibrils are formed from various pathological proteins. Monitoring their aggregation process is necessary for early detection and treatment. Among the available detection techniques, fluorescence is simple, intuitive, and convenient due to its sensitive and selective mode of detection. It has certain disadvantages like poor photothermal stability and detection state limitation. Research has focused on minimising the limitation by developing hybrid fluorescence techniques. This review focuses on the two ways fluorescence (intrinsic and extrinsic) has been used to monitor amyloid fibrils. In intrinsic/label free fluorescence: i) The fluorescence emission through aromatic amino acid residues like phenylalanine (F), tyrosine (Y) and tryptophan (W) is present in amyloidogenic peptides/protein sequence. And ii) The structural changes from alpha helix to cross-β-sheet structures during amyloid formation contribute to the fluorescence emission. The second method focuses on the use of extrinsic fluorophores to monitor amyloid fibrils i) organic dyes/small molecules, ii) fluorescent tagged proteins, iii) nanoparticles, iv) metal complexes and v) conjugated polymers. All these fluorophores havetheir own limitations. Developing them into hybrid fluorescence techniques and converting it into biosensors can contribute to early detection of disease.

Optical Characteristics of the Black Seed Oil: Fluorescence and Adulteration Detection.

Understanding the optical characteristics, especially the fluorescence properties of vegetable oils, particularly black seed oil (BSO), is an essential prerequisite for the development of the future applications in both medicinal and nutritional fields. In this way, it is essential to identify the roles played by the components such as unsaturated fatty acids, carotenoids, flavonoids, vitamin E, and chlorophylls in the BSO fluorescence spectra. In the current landscape, challenges arise from the adulteration of BSO with impurities such as sunflower oil (SO), complicating efforts to obtain pure BSO. Here, dependence of the BSO fluorescence on excitation wavelength has been examined using UV- visible diode lasers (λ = 355, 405, 440, 532 and 660nm) as excitation sources. Though conjugated unsaturated fatty acids, flavonoids and chlorophylls are mainly contributed to the fluorescence due to UV excitation, wavelengths in the visible range specifically excite carotenoids, vitamin E, and chlorophylls. By utilizing the laser-induced fluorescence (LIF) technique, we explored the effects of inner filters and setup geometry to gain deeper insights into the BSO fluorescence dynamics. Differential spectral analysis (DSA) revealed that adulteration of BSO with SO alters its fluorescence features. As a result, a novel approach is proposed for adulteration detection, based on the simultaneous excitation of BSO and SO by a 405nm laser, benefit to indirect excitation of the carotenoids of BSO by fluorescence emission of SO within the spectral range of 400-500nm, which results in the enhancement of BSO fluorescence in the region of 500-600nm.

EVALUATION OF REUSE WATER FROM THE PINHEIROS METRO STATION IN THE CITY OF SÃO PAULO (BRAZIL) FOR THE PRESENCE OF METALS USING THE X-RAY FLUORESCENCE TECHNIQUE WITH SYNCHROTRON RADIATION

Ensuring the conservation of water reserves is a challenge for all humanity, which makes it essential to continuously study new ways of treating and using water sources on the planet. One of the focuses of water conservation and sustainability is the reuse of water sources in order to guarantee the continuity of the main reserves of drinking water for activities such as waterlogging and food production. The present study aimed to investigate the quality of the water used for reuse at the Pinheiros subway station in the city of São Paulo (Brazil) in order to assess the degree of presence of heavy metals and other chemical elements using the X-ray fluorescence technique by synchrotron radiation at the National Synchrotron Light Laboratory (LNLS). The data collection for a sample collected in the summer and analyzed revealed a pH of 6.8 and the presence of 19 chemical elements using the technique with concentrations in the order of ng.mL -1 , with emphasis on the presence of lead (Pb).

Determination and analysis of spectral fluorescence cross-sections of bacteria aerosols

Fluorescence cross-sections of single bacteria provide information on the strength of fluorescence response of bacteria for particular excitation conditions and give hints about a possible distinguishability of bacteria by fluorescence techniques. In this report, the fluorescence cross-sections of dry bacteria aerosols are derived from fluorescence spectra by absolute calibration of the measuring system. The fluorescence is measured in a continuous aerosol flow. The aerosol concentration is calculated from microscopic analyses of bacteria samples taken from the aerosol flow. Established calibration methods such as Mie scattering from monodisperse spheres and Raman scattering from water are applied to the same set of fluorescence spectra. The cross-section data obtained are evaluated with regard to their independency from the applied measuring system. The results are compared to data published in the literature. Polarization effects are identified to contribute to the discrepancies between the different datasets.Graphical abstract

Rapid and Efficient Dual Detection Of Zn2+ Ions and Oxytetracycline Hydrochloride Using a Responsive Fluorescent "On-Off" Sensor Based on Simple Salen-Type Schiff Base Ligand.

This research has progressed to an effective detection chemosensor of zinc, aluminum ions and oxytetracycline hydrochloride antibiotic based on the fluorescence technique. A straightforward method utilizing microwave irradiation was employed to synthesize the salen-type Schiff base ligand N,N'-bis(salicylaldehyde)4,5-dichloro-1,2-phenylenediamine (H2I), providing a good 70 % yield. In ethanol, the H2I sensor demonstrated remarkable rapidity, selectivity, and sensitivity in detecting zinc ions. The fluorescence spectrum exhibited a 44-fold substantial enhancement at 522 nm and achieved a low limit of detection (LOD) of 1.47 μM. Furthermore, the H2I probe's emission intensity increased by 124 times when compared to the ligand's ability to detect Al3+ ions at 494 nm with a LOD value of 7.4 μM. Additional research was done using the H2I probe's effective Zn2+ detection capability. The ability to recognize zinc ions in different real water samples demonstrated a recovery rate of 98.67 % to 103.31 %. Interestingly, a naked-eye visible fluorescence color of H2I solution impregnated filter papers turned colorless into yell ow under UV irradiation by adding Zn2+ ions, renders it suitable for developing a practical zinc ion detection kit test. In particular, the I-Zn2+ complex effectively quenched the fluorescence toward oxytetracycline hydrochloride (OTC) with a LOD value of 1.49×10-2 μM in DMSO:H2O (6 : 4, v/v). This is a novel and effective procedure for sensing OTC antibiotic by the I-Zn2+ complex. These findings hold immense potential for the development of dual fluorescent probes, thereby enhancing sensitivity and specificity in identifying metal ions and antibiotics in a wide range of applications.

Specificity determinants of pathogens in forest

Abstract Host‐specific pathogens have long been suggested to act as a major driver of species diversity in tropical forests. However, determining the degree of host specificity of potential pathogens coupled to key cellular characteristics of infection is difficult and time‐consuming. These challenges have delayed progress in relating the functional specificity of pathogenic fungi to ecological consequences. We tested the pathogenicity of 27 (of 215) fungi that were isolated from surface sterilized roots of seedlings from four common tree species in a diverse subtropical forest. Inoculation experiments showed that six fungi exhibited strong pathogenicity on the host seedlings. Five of these only infected their specific hosts (i.e. host‐specific pathogen species). Green fluorescent protein labelling revealed that in three host‐specific pathogens fungal hyphae were able to grow into the vascular tissues only in their specific host plant, in contrast to other fungal‐host combinations that exhibit non‐pathogenic interactions. This fluorescent labelling technique allows direct tracking of the progress of fungal infection in different host tissues. Synthesis. By coupling the green fluorescent protein technique with standard host inoculation experiments, we determined the developmental differences between infections by pathogenic and non‐pathogenic fungi in a relatively simple and straightforward way. Our work provides a useful tool for rapidly screening and categorizing host–fungal interactions, reflecting the functional basis of host specificity of pathogenic fungi. More broadly, this technique can contribute to understanding the roles of pathogens in species coexistence and biodiversity maintenance in forest communities.

Spectral induced polarization measurements to detect different scales in oil and gas production tubing

Different varieties of scales, such as iron sulfide (FeS) scale, and calcium carbonate (CaCO3), commonly precipitate within oil and gas production tubing, posing operational challenges and production losses. It is essential to implement efficient mitigation strategies and preserve production integrity to detect and characterize these scales in an accurate and efficient manner. Prior studies have explored Spectral induced Polarization (SIP) for the early detection of FeS within porous media, mainly for environmental applications or for identifying FeS in carbonate formations from the perspective of reservoir characterization. This study focuses on applying SIP to address production-related issues in production tubing. For this purpose, six actual subsurface scale samples were analyzed using X-ray Diffraction, X-ray Fluorescence, and SIP techniques. These samples were categorized into three primary groups based on their composition: Pyrrhotite, Goethite, and Calcium Sulfate Hydrate or Calcite. The results indicate that combining phase shift and conductivity as frequency functions makes it possible to develop an approach to classify and differentiate between various scale types. This information could be instrumental in developing methods that can be potentially integrated into tubing systems to detect and characterize the different scale types.

Microplastics contamination in popular soft drinks and non-alcoholic beverages marketed in Iran: Quantity and characteristics

Given the increasing reliance on plastic packaging in the beverage industry, this study investigates the presence of microplastics (MPs) in the most popular beverage brands in the Iranian market. A total of 19 bottled beverage brands, including soft drinks and non-alcoholic beverages, were randomly collected and filtered. Quantitative analysis of the MPs was then performed using stereomicroscopy and fluorescence techniques, and classification was based on color, shape, and size. In addition, the polymer type was determined using Fourier transform infrared spectroscopy (FT-IR), and the surface morphology and elemental composition of the MPs were examined using Scanning Electron Microscopy (SEM) and Energy dispersive X-ray spectroscopy (EDS). The results showed that approximately 80–90 % of the samples were contaminated with different MP types, with an average of 4.5 ± 4.8 particles/L detected by stereomicroscopy and 21.90 ± 25.72 particles/L by fluorescence microscopy. FT-IR analysis identified polyethylene terephthalate (PET) and polyethylene (PE) as the predominant polymer types and may clarify the possible role of packaging materials in the contamination of MPs. Fragments accounted for the highest proportion of MPs (71 %), followed by fibers (29 %). The size distribution of MPs was dominated by particles in the range of 1–500 μm (48 %), followed by 500–1000 μm (40 %) and 1000–1500 μm (12 %). MPs were black (84 %), with smaller proportions of red (7 %) and green (1 %), which may reflect the source of the contamination. The findings emphasize the necessity of increased monitoring and the application of countermeasures to lessen MPs contamination in the beverage sector.

Determination of trace uranium concentrations in spent‐fuel reprocessing using online graphite crystal pre‐diffraction energy‐dispersive x‐ray fluorescence

AbstractAn online graphite crystal pre‐diffraction x‐ray fluorescence technique was developed for accurate real‐time detection of trace uranium concentrations in spent‐fuel reprocessing streams. Online analysis for determining uranium concentrations was established. The device was equipped with measurement windows in both the flow cell and a side wall of the glove box. X‐ray tubes and detectors were arranged outside the glove box, and the process stream flowing through the flow cell was measured through the measurement window. A cylindrical highly oriented pyrolytic graphite crystal was located in front of the detector to improve detection efficiency and to provide monochromatic uranium‐characteristic x‐rays. At the same time, the device could perform remote online automatic calibration. The uranium detection limit in a kerosene solution was 0.08 mg/L, and the quantitative limit was 0.27 mg/L. The detection limit in a nitric acid solution was 0.11 mg/L, and the quantitative limit was 0.37 mg/L. The relative standard deviation of measuring 0.5 mg/L uranium was less than 10%, which greatly improved online monitoring of trace uranium in spent‐fuel reprocessing samples.

Isotopically Enriched Lithium Fluoride Crystals for Detection of Neutrons with the Fluorescent Track Technique.

In this work, the properties of LiF crystals grown using Li of different isotopic compositions are described from the standpoint of their application as fluorescent nuclear track detectors used in measurements in the neutron radiation fields. The crystals were grown using two techniques: the Czochralski method and the micro-pulling-down method. Three isotopic compositions of Li were studied: natural, highly enriched in 6Li, and highly enriched in 7Li. It was found that 6LiF detectors are about six times more sensitive to thermal (low energy) neutrons than natural LiF, which significantly decreases the lower detection limit. 7LiF detectors are insensitive to thermal neutrons, which makes it easier to detect tracks due to other radiation modalities, such as energetic ions or nuclei recoiled in collisions with high-energy neutrons. Besides the response to neutron radiation, no other significant differences in the crystal properties were identified, irrespective of the isotopic composition and crystal growth method employed.

Light-Triggered Plasmonic DNAzyme Walker Enables Precise Subcellular Molecular Imaging with Reduced Off-Mitochondria Signal Leakage.

The development of highly sensitive and precise imaging techniques capable of visualizing crucial molecules at the subcellular level is essential for elucidating mitochondrial functions and uncovering novel mechanisms in biological processes. However, traditional molecular imaging strategies are still limited by off-mitochondria signal leakage because of the "always-active" sensing mode. To address this limitation, we have developed a light-triggered activation sequence activated plasmonic DNAzyme walker (PDW) for accurate subcellular molecular imaging by the combination of an organelle localized strategy, upconversion nanotechnology, and a plasmon enhanced fluorescence (PEF) technique. Exploiting the advantage of light activation enables precise control over when and where to activate the probe's sensing function, effectively reducing off-mitochondria signal leakage as validated by the dynamic monitoring of changes in off-mitochondria signals during the mitochondrial entry process. Furthermore, by leveraging the PEF capability of triangular gold nanoprisms (Au NPRs), the fluorescence intensity can be enhanced by approximately 11.9 times, ensuring highly sensitive and accurate subcellular molecular imaging.

Investigation of the molecular interaction between apraclonidine, an α2-adrenergic receptor agonist, and bovine serum albumin using fluorescence and molecular docking techniques

Apraclonidine (APR) is a potent and selective α2-adrenergic receptor agonist used in the diagnosis of Horner’s Syndrome, and the residuals of APR that accumulate in tissues of animals can cause central nervous and cardiovascular systems influences in humans. Therefore, to understand the influence of APR on human health, we examined the interaction of APR with the carrier protein in plasma, bovine serum albumin (BSA). The BSA fluorescence signal was quenched due to the APU–BSA complex formation and a weak binding affinity was estimated between APR and BSA. The inclusion of fluorescence, UV–vis absorption, molecular docking, and dynamics simulation techniques employed to broadly investigate the combination of APR with BSA at typical physiological conditions. The thermodynamic results revealed that enthalpy (ΔH0) and entropy (ΔS0) changes were computed as +11.14 kJ mol−1 and +97.56 J mol−1 K−1, respectively, which represented the binding is principally entropy-driven and the hydrophobic forces acting a significant role in the reaction. Analysis of synchronous and 3-D fluorescence signals revealed microenvironmental variations close to BSA’s Trp and Tyr residues upon APR addition. Both the competitive site marker as well as molecular docking results detected that APR exhibited a stronger binding affinity towards Drug Site 2 (DS2) compared to Drug Site 1 (DS1).

A-147 Comparative Precision of Platelet Counting by Optical, Fluorescent, and Impedance Techniques in Thrombocytopenia and Microcytosis Patients

Abstract Background In today's era of automation driven by Artificial Intelligence, even the most efficient automated hematology analyzer may struggle to accurately determine platelet count in patients with low platelet count and microcytosis. The Sysmex XN-series analyzer (Sysmex, Kobe, Japan) uses optical density, fluorescence, and electronic impedance methods for platelet counting. This study aimed to evaluate the accuracy of optical, fluorescence, and electrical impedance methods in estimating precise platelet counts in thrombocytopenic and microcytic patient samples. Methods A cross-sectional study was conducted in the Department of Laboratory Medicine at AIIMS, New Delhi, for 30 days consecutively. A total of 200 blood samples collected, of which 100 samples were of thrombocytopenia (<100x10^9/L) and 100 samples were of microcytosis (Mean corpuscular volume <76 femtoliters). MCV<76 fl was further categorized into 2 groups- MCV 60-70 fl and MCV 71-76 fl accordingly. Males and females were categorized and analyzed distinctly for thrombocytopenia and microcytosis. Statistical analysis was performed using SPSS 16.0 for Windows (SPSS Inc., Chicago, IL, USA) and the Bland Altman plot was analyzed. Results Of the 100 patients with thrombocytopenia (platelet<1 lakh/L) females were predominantly 54% while males were 46% and the median age was 29 years (0.02-70). Of the 100 patients with low MCV (<76 fl) females were 53%, while males were 47% and the median age was 29 years (0.3-69). The findings were compared against the standard manual platelet count method in peripheral smears verified by two expert pathologists. The Bland Altman plot for Platelet <1 lakh/L and MCV <76 fl were compared with standard manual platelet count method and the following findings were obtained i) In female with PLT- <1 lakh/L, PLT-O showed least bias (9.8) followed by PLT-F (10.4) and PLT-I (12.1) ii) In males with PLT-<1 lakh/L, PLT-O showed least bias(14.1) followed by PLT-F(16.5) and PLT-I(17.0) iii) For MCV 61-70fl, PLT-O showed the least bias (4.4) followed by PLT-F (6.7) and PLT-I (28.5) iv)For MCV 71-76fl, PLT-F showed least bias (-0.2) followed by PLT-O (1.5) and PLT-I(31.2). Conclusions Platelet count by optical method (PLT-O) detects platelet count more accurately with minimum bias when compared with PLT-F and PLT-I in patients with thrombocytopenia. In patients with microcytosis, PLT-I is less reliable in comparison to PLT-O and PLT-F. A limitation of the automated hematology analyzer is the inability to detect platelet clumps which is appreciated in peripheral smears.

Study on the flame structure and flow field of hydrogen-enriched combustion in array micro-tube

Addressing climate change and reducing greenhouse gas emissions are critical priorities. Utilizing hydrogen-rich methane or pure hydrogen as fuels within gas turbines, facilitated by array micro-tube premixed combustion technology, is anticipated to markedly accelerate the decarbonization process of the energy sector. In this study, the flame structure of the array micro-tube premixed burner under various fuel compositions was examined using OH-Planar Laser-Induced Fluorescence and Particle Image Velocimetry measurement techniques. The effects of the equivalence ratio (φ) and the hydrogen power ratio (HPR) on the characteristics of the flame front, including its curvature, density, volume, and the associated flow field properties, were discussed. As φ and HPR increase, the wrinkled structure of the flame front is significantly enhanced, with a more pronounced effect on smaller scales. This enhancement leads to the separation of the unburned pockets from the main flame. Concurrently, both the flame length and the flame area decrease with the augmentation of φ and HPR, indicating a more concentrated combustion process and increased combustion intensity under hydrogen-enriched and pure hydrogen conditions. The study also observed a slight increase in both the negative and positive curvatures of the flame front, with a more notable increase in the negative curvature. The increased negative curvature results in an elevated degree of wrinkling and a higher value of Σ (flame surface density), reaching a maximum of 0.876 mm−1 under the conditions where φ is 0.8 and ⟨c⟩ (mean progress variable) is 0.5, resulting in the smallest observed flame volume of 100.6 mm3. Upon coupling the flame with the flow field, it was discovered that the exit flow field of the array micro-tube exhibits symmetry and a characteristic conical flame shape. The burning velocity of the side flame brushes increases, and the velocity peak shifts upstream. The aforementioned findings confirm that the addition of hydrogen increases the laminar flame velocity, enabling the flame to stably anchor to the microtube outlet and thereby enhance the flame's robustness and stability.

Carica papaya L. Latex Mediated Green Synthesis of Zno Nanoparticles for its Antimicrobial Activity

Zinc oxide nanoparticles have gained potential recognition because of their distinctive characteristics and wide utilizatrion in various fields. Therefore, development of novel biological techniques is significant for the biosynthesis of ZnO nanoparticles using the latex of Carica papaya L. Plant latex is a natural product produced by a number of plant species which are used by different tribal communities in India as a folk medicinal treatment on natural wounds or cuts. Plant latex has a huge demand as herbal products in an aspect of clinical, therapeutical and also in agricultural sectors. Natural latex is composed of different important biomolecules like, tannins, flavonoids, glycosides, sterols, saponins etc. These different active chemical constituents have versatile medicinal activities against different pathogens such as bacteria, fungi, viruses and protozoans etc. This study reports on the biosynthesis of ZnO nanoparticles (Zn NPs)using latex of C. papaya as an effective reducing agent. Green synthesis of nanoparticles has advantageous over conventional methodsbecause it does not require the use of toxic chemicals and therefore environmentally sustainable. The elemental composition of C. papaya latex was also analysed using X-ray Fluorescence (XRF) technique. Properties of synthesized ZnO NPs were characterized using various methods such as ultra violet visible spectrophotometer (UV-Vis), scanning electron microscopy and Fourier transform infrared spectroscopy. Green synthesized ZnO nanoparticles also assessed for its antimicrobial activity against selected bacterial and fungal species.

Hydroxyl functionalized hexagonal boron nitride quantum dots as nanozyme for pesticides sensing through dual colorimetric and fluorometric platform: A combined experimental and theoretical study

The Hydroxyl-functionalized hexagonal boron nitride quantum dots (h-BN QDs) were synthesized using a hydrothermal technique in a water medium, exhibiting stability in water for over 90 days. The present study demonstrates two simple fluorescence and colorimetric techniques for sensing organophosphorus (OP) and organochloride (OC) pesticides (atrazine, simazine and chlorpyrifos) in an aqueous medium using hydroxyl-functionalized h-BN QDs. The sensing capability of h-BN QDs for these pesticides was determined to be in the range of 5–10 µM using both techniques. The hydroxyl groups on the surface of the QDs enhanced dispersibility and enabled peroxidase-like catalytic activity in acidic conditions. The radical generation using hydroxyl-functionalized h-BN QDs in the presence of H2O2 upon 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) oxidation plays a significant role in the peroxidase reaction. The hydrogen bonding and π-π interactions between the pesticide molecules and ABTS can enhance the pesticide sensing performance. The limit of detection (LOD) using ABTS for atrazine, simazine, and chlorpyrifos was 6.11, 6.56, and 2.47 µM, respectively. Fluorescence sensing, based on a turn ON/OFF mechanism, demonstrated high specificity and sensitivity with LODs of 5.59, 6.45, and 8.08 µM for the same pesticides. The DFT studies revealed non-covalent bonding, such as hydrogen bonding, π-π interactions between the pesticides and the h-BN QDs, indicating binding affinities and stabilization energies of the complexes which can detect pesticides effectively. Atrazine exhibited higher binding affinity towards h-BN QDs, followed by simazine and chlorpyrifos. The h-BN QDs provide a new insight into bonding with pesticides, enhancing the peroxidase mimetic and fluorescence activity.

Chromium uptake and its impact on antioxidant level, photosynthetic machinery, and related gene expression in Brassica napus cultivars.

The development of heavy metals, particularly chromium (Cr)-tolerant crop cultivars, is hampered due to lack of understanding of the mechanisms behind Cr stress tolerance. In this study, two Brassica napus cultivars, ZS758 and ZD622, were compared for Cr stress resistance by using the chlorophyll a fluorescence technique and biochemical characteristics. In both cultivars, Cr stress dramatically decreased PSII and PSI efficiency, biomass accumulation, and antioxidant enzyme levels. Although, cultivar ZS758 showed reduction in oxidative stress by decreasing the production of reactive oxygen species (ROS) in terms of reduced H2O2 and MDA content and increased enzymatic activities of key antioxidants enzymes including SOD, APX, CAT, and POD activities that play a crucial role in the regulation of numerous transcriptional pathways involved in oxidative stress responses. Higher non-photochemical quenching (NPQ) and QY were found in tolerant ZS758 cultivar under Cr stress, indicating that tolerant cultivar had a greater capacity to preserve PSII activity under Cr stress by enhancing heat dissipation as a photo-protective component of NPQ. Lower PSI activity and electron transfer from PSII were confirmed by lower PSI efficiency and higher donor end limitation of PSI in both rapeseed cultivars. The Cr concentration was greater in the ZD622 as compared to ZS758, which affected the mineral nutrients profile and damaged the cellular ultrastructure and related gene expression levels. However, current study suggest that cultivar ZS758 is more resistant to Cr stress than ZD622 due to improved metabolism and structural integrity and Cr stress tolerance that is linked with the increased PSII activity, NPQ, and antioxidant potential; these physiological characteristics can be exploited to select cultivars for Cr stress tolerance.