Search Results (283)

The search for sustainable, economically viable, and effective plant protection strategies against pathogenic bacteria, fungi, and viruses is a major challenge in modern agricultural practices. Chitosan (CS) is an abundant cationic natural biopolymer known for its biocompatibility, low toxicity, and antimicrobial properties. Its potential use in agriculture for pathogen control is a promising alternative to traditional chemical fertilisers and pesticides, which raise concerns regarding public health, environmental protection, and pesticide resistance. This study focused on the preparation of chitosan nanoparticles (CS-NPs) through cross-linking with organic molecules, such as tannic acid (TA). Various formulations were explored for the development of stable nanoscale particles having encapsulation capabilities towards low compounds of varying polarity and with potential agricultural applications relevant to plant health and growth. The solution properties of the NPs were assessed using dynamic and electrophoretic light scattering (DLS and ELS); their morphology was observed through atomic force microscopy (AFM), while analytical ultracentrifugation (AUC) measurements provided insights into their molar mass. Their properties proved to be primarily influenced by the concentration of CS, which significantly affected its intrinsic conformation. Additional structural insights were obtained via infrared and UV–Vis spectroscopic measurements, while detailed fluorescence analysis with the use of three different probes, as model cargo molecules, provided information regarding the hydrophobic and hydrophilic microdomains within the particles. Full article

The most important bauxite deposits in Türkiye are located in the Seydişehir (Konya) and Akseki (Antalya) regions, situated along the western Taurus Mountain, with a total reserve of approximately 44 million tons. Some of the bauxite deposits have been exploited for alumina since the 1970s. In this study, bauxite samples, collected from six different deposits were examined to determine their mineralogical and chemical composition, as well as their REE content, with the aim of identifying which bauxite types are enriched in REEs and assessing their economic potential. The samples included massive, oolitic, and brecciated bauxite types, which were analyzed using optical microscopy, X-ray diffraction (XRD), X-ray fluorescence (XRF) and inductive coupled plasma-mass spectrometry (ICP-MS), field emission scanning electron microscopy (FESEM-EDX), and electron probe micro-analysis (EPMA). Massive bauxites were found to be more homogeneous in both mineralogical and chemical composition, predominantly composed of diaspore, boehmite, and rare gibbsite. Hematite is the most abundant iron oxide mineral in all bauxites, while goethite, rutile, and anatase occur in smaller quantities. Quartz, feldspar, kaolinite, dolomite, and pyrite were specifically determined in brecciated bauxites. Average oxide contents were determined as 52.94% Al₂O₃, 18.21% Fe₂O₃, 7.04% TiO₂, and 2.69% SiO₂. Na₂O, K₂O, and MgO values are typically below 0.5%, while CaO averages 3.54%. The total REE content of the bauxites ranged from 161 to 4072 ppm, with an average of 723 ppm. Oolitic-massive bauxites exhibit the highest REE enrichment. Cerium (Ce) was the most abundant REE, ranging from 87 to 453 ppm (avg. 218 ppm), followed by lanthanum (La), which reached up to 2561 ppm in some of the massive bauxite samples. LREEs such as La, Ce, Pr, and Nd were notably enriched compared to HREEs. The lack of a positive correlation between REEs and major element oxides, as well as with their occurrences in distinct association with Al- and Fe-oxides-hydroxides based on FESEM-EDS and EPMA analyses, suggests that the REEs are present as discrete mineral phases. Furthermore, these findings indicate that the REEs are not incorporated into the crystal structures of other minerals through isomorphic substitution or adsorption. Full article

The development of rapid detection methods to identify mercury ions in aqueous solutions is crucial for effectively monitoring environmental contamination. Fluorescent chemical sensors offer a fast and reliable approach to detect and analyze these metal ions. In this study, a sensor utilizing aggregation-induced emission (AIE) is introduced as a ’turn-on’ fluorescent sensor specifically designed for mercury ions in aqueous solutions. The sensor, based on carbazole, forms aggregates in aqueous solutions, resulting in a significant 800% enhancement of its fluorescence signal. When elemental iodine is added to the solution, the fluorescence of the aggregates is quenched by 90%. However, upon subsequent addition of mercury ions, the fluorescence is regenerated, and the intensity of the emission signal is directly proportional to the concentration of the ions across a wide concentration range. The carbazole-iodine complex acts as a fluorescent probe, enabling the detection of mercury ions in aqueous solutions. Full article

N,N-Dimethyl N-[4-[[[2-(4-methylphenyl)-6,7-dihydro-5H-benzocyclohepten-8-yl]carbonyl]amino]benzyl]tetra-hydro-2H-pyran-4-aminium chloride (TAK779) has a potent binding affinity for the chemokine receptor CCR5 and low cytotoxicity; however, their interaction remains unknown. We designed and synthesized four fluorescence-labeled TAK779 analogs as chemical probes. Although the binding properties of the fluorescence-labeled TAK779 analogs for CCR5 could not be determined, it was found that they penetrate the cell membranes and localize to the microtubes of HeLa cells. Full article

Micro and nanoplastics, pervasive environmental pollutants, pose significant threats to ecosystems and human health, necessitating urgent research and innovative solutions. Several research groups have investigated the uptake of synthetic microplastics (MPs) and nanoplastics (NPs) using various model organisms. We investigated the uptake and the growth inhibitory effect of polystyrene (PS) and polymethacrylate (PMA)-based MPs and NPs in Tetrahymena pyriformis. Carboxyl-modified PS-MPs showed a greater growth inhibitory effect than amine-modified PS-MPs and PMA-based MPs. We also studied the impact of these particles on the transcriptomics of T. pyriformis and observed that PS-MPs directly impact various signaling pathways related to oxidative stress. PMA-based MPs showed differential expressions of signaling pathways related to cancer and some related to oxidative stress. Using a fluorescent probe, we measured the reactive oxygen species (ROS) generated by carboxyl-modified PS-MPs and PMA-MPs and observed that PS-MPs generated greater ROS than PMA-MPs. This study suggests that it is important to understand the type and the nature of chemical modification of various MPs and the specific signaling pathways in particular oxidative-related pathways they target on diverse groups of organisms, as this will provide key information related to the effect of various modified MPs and NPs on human health. Full article

The liver is an essential metabolic organ that is involved in energy metabolism, protein synthesis, and detoxification. Many endogenous and exogenous factors can cause liver injury, a complex pathological condition. It poses a serious risk to human health due to its extremely varied clinical manifestations, which range from mild fatty liver to liver fibrosis, cirrhosis, and even hepatocellular carcinoma. Because of their low specificity, lack of real-time monitoring, and invasiveness, traditional diagnostic techniques for liver injury, such as histopathological examination and serological analysis, have inherent limitations. Fluorescent probe technology, which offers high sensitivity, non-invasiveness, and real-time imaging capabilities, has become a potent tool in liver injury research and early diagnosis in recent years. The pathophysiology of liver injuries caused by alcohol, chemicals, drugs, and the immune system is methodically covered in this review, along with new developments in fluorescent probe development for their detection. The focused imaging properties of various fluorescent probes are highlighted, along with their possible uses in drug screening and early liver injury detection. This review attempts to offer theoretical insights to support the optimization of precision diagnostic and therapeutic approaches by summarizing these findings. Full article

Rare-earth-doped upconversion nanoparticles (UCNPs) have been widely used in biological detection due to their unique anti-Stokes shift, stable chemical properties, tunable emission wavelengths, and low biotoxicity. However, their low fluorescence quantum yield remains a challenge. Constructing a high-performance detection platform based on UCNPs is therefore a critical consideration. Focusing on the biological detection applications of UCNPs, this paper introduces the fundamental principles of upconversion and the design of upconversion fluorescence probes. It then summarizes common strategies for enhancing upconversion luminescence and three biosensing platform formats: solution-based, strip-based, and plate-based. Finally, future directions for UCNPs in biological detection are discussed. Full article

Desulfovibrio vulgaris is an anaerobic microorganism belonging to the group of sulphate-reducing bacteria (SRB). SRB form biofilms on metal surfaces in water supply networks, producing a microbiologically influenced corrosion (MIC). This process produces the deterioration of metal surfaces, leading to high economic costs and different environmental safety and health problems related to its chemical treatment. For that reason, rapid and accurate detection methods of SRB are needed. In this work, a new detection system for Desulfovibrio has been developed using gated nanoporous materials. The probe is based on hybrid nanoporous alumina films encapsulating a fluorescent molecule (rhodamine B), whose release is controlled by an oligonucleotide gate. Upon exposure to Desulfovibrio’s genomic material, a movement of the oligonucleotide gatekeeper happens, resulting in the selective delivery of the entrapped rhodamine B. The developed material shows high selectivity and sensitivity for detecting Desulfovibrio DNA in aqueous buffer and biological media. The implementation of this technology for the detection of Desulfovibrio as a tool for monitoring water supply networks is innovative and allows real-time in situ monitoring, making it possible to detect the growth of Desulfovibrio inside of pipes at an early stage and perform timely interventions to reverse it. Full article

Ternary metal chalcogenide quantum dots (QDs), such as CuInS₂, have attracted significant attention due to their lower toxicity compared to binary counterparts containing cadmium or lead, making them promising candidates for biomedical imaging and solar energy applications. The surfactant choice is critical for controlling nanocrystal nucleation, growth kinetics, and functionalization. This directly affects the toxicity and applications of QDs. In this work, we report a synthesis protocol for PVP-capped CuInS₂ QDs in an aqueous solution. Using density functional theory (DFT) calculations, we predicted the coordination patterns of PVP on the CuInS₂ QDs surface, providing insights into the stabilization mechanism. The synthesized QDs were characterized using TEM, XRD, XPS, and FTIR to assess their morphology, chemical composition, and surface chemistry. The QDs exhibited dual photoluminescence (PL) maxima at 550 nm and 680 nm, attributed to defect-related emissions, making them suitable for cell imaging applications. Cytotoxicity studies and cell imaging experiments demonstrate the excellent biocompatibility and effective staining capabilities of the PVP-capped CuInS₂ QDs, highlighting their potential as fluorescent probes for long-term, multicolor cell imaging including two-photon microscopy. Full article

In cytogenetics, the ability to perform FISH (Fluorescence In Situ Hybridization) experiments using probes that map very closely together depends on the capacity to produce sufficiently long chromosomes. Traditionally, colcemid is the chemical agent used to obtain metaphase spreads. However, various substances have been reported to arrest cells in an earlier stage of mitosis than the metaphase, potentially providing longer chromosomes. In this study, we tested seven substances different from colcemid, which, according to the literature, have this capability: Vinblastine, Combretastatin A-4, Podophyllotoxin, Org9935, Nocodazole, Paclitaxel, and Griseofulvin. All substances were tested on lymphocyte cultures derived from whole blood at the same concentration: 0.1 µg/mL. Among these, Org9935 and Griseofulvin were confirmed to have the ability to produce metaphases with longer chromosomes compared to those obtained with colcemid. Full article

Curcumin (Cur) is one of the most studied natural polyphenolic compounds, with many pharmacological properties and a luminescent skeleton. Natural fluorescent molecules are peculiar tools in nanomedicine for bioimaging and sensing, and this review focuses on the photophysical properties and applications of Cur in these biomedical fields. The first part of the review opens with a description of the Cur chemical skeleton and its connection with the luminescent nature of this molecule. The 1,6-heptadiene-3,5-dionyl chain causes the involvement of Cur in a keto–enol tautomerism, which influences its solvatochromism. The polyphenolic nature of its skeleton justifies the Cur generation of singlet oxygen and ROS upon photoexcitation, and this is responsible for the photophysical processes that may be related to the photodynamic therapy (PDT) effects of Cur. In the second part of the review, bioimaging based on Cur derivatives is reviewed, with a deeper attention paid to the molecular diagnostic and nano-formulations in which Cur is involved, either as a drug or a source of fluorescence. Theragnostics is an innovative idea in medicine based on the integration of diagnosis and therapy with nanotechnology. The combination of diagnostics and therapy provides optimal and targeted treatment of the disease from its early stages. Curcumin has been involved in a series of nano-formulations exploiting its pharmacological and photophysical characteristics and overcoming its strong lipophilicity using biocompatible nanomaterials. In the third part of the review, modifications of the Cur skeleton were employed to synthesize probes that change their color in response to specific stimuli as a consequence of the trapping of specific molecules. Finally, the methodologies of sensing biothiols, anions, and cations by Cur are described, and the common features of such luminescent probes reveal how each modification of the skeleton can deeply influence its natural luminescence. Full article

Fluorescent sensors are indispensable tools in fields such as molecular biology, clinical diagnostics, biotechnology, and environmental monitoring, due to their high sensitivity, selectivity, biocompatibility, rapid response, and ease of use. However, conventional fluorophores often suffer from aggregation-caused quenching (ACQ), leading to diminished fluorescence in the aggregated state. The advent of aggregation-induced emission (AIE) luminogens, which exhibit enhanced fluorescence upon aggregation, offers a powerful solution to this limitation. Their unique photophysical properties have made AIE-based materials highly valuable for diverse applications, including biomedical imaging, optoelectronics, stimuli-responsive systems, drug delivery, and chemical sensing. Notably, AIE-based fluorescent probes are emerging as attractive alternatives to traditional analytical methods owing to their low cost, fast detection, and high selectivity. Over the past two decades, considerable progress has been made in the rational design and development of AIE-active small-molecule fluorescent probes for detecting a wide variety of analytes, such as biologically relevant molecules, drug compounds, volatile organic compounds (VOCs), explosives, and contaminants associated with forensic and food safety analysis. This review highlights recent advances in organic AIE-based fluorescent probes, beginning with the fundamentals of AIE and typical “turn-on” sensing mechanisms, and concluding with a discussion of current challenges and future opportunities in this rapidly evolving research area. Full article

Vomitoxin is a member of the monotrichous mycotoxin family with a complex chemical structure and significant biological activity. This toxin has strong immunosuppressive toxic effects and can cause serious damage to human and animal health. In this study, an on-site immune detection method based on an immune SiO₂@QD fluorescent probe was developed, which realized the rapid and quantitative detection of emetic toxins in grains. Polyethyleneimine (PEI) is a polymer containing a large number of amino groups, and the binding of PEI to the surface of quantum dots can serve to regulate growth and provide functionalized groups. A SiO₂@QD nanotag with good dispersibility and a high fluorescence intensity was synthesized by combining a PEI interlayer on the surface of SiO₂ nanospheres. Utilizing the electrostatic adsorption of the amino group in PEI, CdSe/ZnS QDs were self-assembled on the surface of SiO₂ nanospheres. In the stability test, the SiO₂@QDs could maintain basically the same fluorescence intensity for 90 consecutive days in the dark at 4 °C, showing a high fluorescence stability. The fluorescence-enhanced QD immune probe was formed by coupling with anti-DON monoclonal antibodies through carbodiimide chemical synthesis. For the detection of spiked wheat flour samples, the immuno-SiO₂@QD fluorescent probe showed excellent sensitivity and stability, the detection limit reached 0.25 ng/mL, and the average recovery rate was 92.2–101.6%. At the same time, the immuno-SiO₂@QD fluorescent probe is simple to operate, is capable of rapid responses, and has great potential in the rapid detection of vomitoxins in grains. Full article

Fungal infections are a major but often neglected global health challenge, affecting both human health and agricultural productivity. Current treatments are limited by few drug classes and increasing multidrug resistance, exacerbated by the widespread use of antifungal agents in clinical and agricultural settings. This study investigates the antifungal potential of a novel 8-hydroxyquinoline derivative with a triazole core at the 5-position, synthesized to improve both efficacy and mechanistic understanding as a fluorescent chemical probe. Biological assays demonstrated significant antifungal activity of compound 10 against a range of pathogens, which was active against all Candida species, dermatophytes, and Fusarium solani with MIC values ranging from 0.5 to 4 µg/mL. Confocal fluorescence microscopy of treated fungal cells was conducted and showed a high accumulation of compound 10 at the cell edge. To further investigate the mode of action, results from a sorbitol protection assay suggested a possible cell wall action, and scanning electron microscopy (SEM) revealed cell wall disruption, such as cell shrinkage and surface roughness, in treated fungal cells. These findings highlight the 8-hydroxyquinoline-triazole scaffold as a promising antifungal agent with cell wall damage properties, providing a basis for future therapeutic development against human and plant fungal pathogens. Full article

Zinc-based MOFs exhibit significant advantages in ion detection due to their unique structure and chemical properties. They can efficiently and selectively recognize and detect specific ions, making them powerful analytical tools for applications in environmental monitoring, biomedical fields, and more. In this work, we used a simple ligand to improve the coordination environment of Zn²⁺ ions and successfully synthesized a 3D coordination compound Zn(all-bdc)(Py) MOF through a straightforward hydrothermal method at low temperature. Additionally, we explored the potential of this MOF as a bifunctional ion fluorescence probe for both cationic and anionic recognition. The results showed that this 3D porous MOF exhibited excellent recognition ability for trivalent iron ions (Fe³⁺) and potassium permanganate (KMnO₄⁻) ions due to its highly porous structures and efficient ion recognition. When iron ions were added to 500 μL and potassium permanganate ions were added to 100 μL, the fluorescence of the compound was effectively quenched, and the detection limits for these two ions were 0.95 μM and 0.13 μM, respectively. The mixed-ion experiments also demonstrated that even in the presence of similar ions, this 3D MOF still maintained good selective recognition ability, specifically identifying Fe³⁺ and KMnO₄⁻ ions. This work provides a novel synthetic strategy for the design of MOFs capable of mixed-ion recognition and detection, expanding their application potential in ion sensing and analysis. Full article