Rhodamine-Immobilised Electrospun Chitosan Nanofibrous Material as a Fluorescence Turn-On Hg2+Sensor

Comparison of Immunomagnetic Bead Separation-Immunosensor Detection and Nested-PCR Methods for Detecting Mycobacterium avium Subspecies paratuberculosis in Cattle Feces

BACKGROUND

Johne's disease, also known as paratuberculosis, is a chronic granulomatous enteritis disease that affects ruminants worldwide.

OBJECTIVE

The objective of this study was to assess the effectiveness of the immunomagnetic bead separation-immunosensor (IMB-IS) detection method compared to Nested-PCR for identifying Mycobacterium avium subspecies paratuberculosis (MAP) infection in cattle feces samples.

METHODS

Ninety rectal fecal samples were collected from selected cattle, comprising 59 serum-positive and 31 serum-negative cases based on serum ELISA. Following DNA extraction, nested-PCR was conducted using the IS900 primer sequence targeting the MAP-specific gene. Immunomagnetic bead (IMB) nanoparticles were synthesized by purifying hyperimmune donkey IgG through affinity chromatography and then conjugating it to Fe nanoparticles. Rhodamine-B hydrazone immunosensor (IS) was synthesized and conjugated to hyperimmune rabbit IgG. The synthesized IMB and IS were used to identify MAP in cattle fecal samples.

RESULTS

The results of this study revealed that of the 90 stool samples tested using the nested-PCR method, 62 samples (68.88%) were positive, while 28 samples (31.12%) were negative. In the IMB-IS test based on optical density (OD), 64 samples were positive (71.1%), while 26 samples were negative (28.8%). This test exhibited a sensitivity of 100%, specificity of 92.85%, and an overall test accuracy of 97.77%.

CONCLUSION

Given the considerations of cost, time, positive and negative predictive values, and acceptable accuracy of the IMB-IS test, it is recommended for evaluation in screening and epidemiological studies.

Seaweed Superheroes: Cystoseira barbata-Incorporated Electrospun Fibers for Lead Ion Sequestration

The efficient removal of lead ions at low concentrations is paramount in combating the significant threat posed by water pollution resulting from industrial activities and population growth. In this study, electrospun C. barbata/PAN fibers were developed to efficiently remove lead(II) ions from water. The morphology, structure, and mechanical properties of the fibers were examined, highlighting that the augmentation of the surface area through the conversion of C. barbata into the polymer fibers facilitates increased metal bonding sites during sorption. C. barbata/PAN fibers exhibited superior characteristics, including higher surface area, smaller pore size, and increased pore volume, compared to powdered C. barbata. The effects of factors such as shaking time, algae percentage, sorbent amount, pH, metal concentration, and temperature on Pb(II) sorption were investigated by the batch method. At an initial ion concentration of 100 μg L-1 and pH 4.0, C. barbata (5 wt %)/PAN fiber demonstrated a notable sorption efficiency of 89-90% (270 μg/g) after 60 min. The equilibrium data align with the Freundlich and Dubinin-Radushkevich isotherm models, whereas the pseudo-second-order kinetic model provides the most suitable description. The characterization of fibers after sorption revealed that carboxyl, hydroxyl, and sulfonyl groups play an active role in Pb(II) sorption.

A Review of Nanotechnology-Enabled Fluorescent Chemosensors for Environmental Toxic Ion Detection

This review examines the utilization of nanotechnology-based chemosensors for identifying environmental toxic ions. Over recent decades, the creation of nanoscale materials for applications in chemical sensing, biomedical, and biological analyses has emerged as a promising avenue. Nanomaterials play a vital role in improving the sensitivity and selectivity of chemosensors, thereby making them effective tools for monitoring and evaluating environmental contamination. This is due to their highly adjustable size- and shape-dependent chemical and physical properties. Nanomaterials possess distinct surface chemistry, thermal stability, high surface area, and large pore volume per unit mass, which can be harnessed for sensor development. The discussion encompasses different types of nanomaterials utilized in chemosensor design, LOD, their sensing mechanisms, and their efficacy in detecting specific toxic ions. Furthermore, the review explores the progress made, obstacles faced, and future prospects in this rapidly evolving field, highlighting the potential contributions of nanotechnology to the creation of robust sensing platforms for environmental monitoring.

Chitosan grafting coumarin-3-carboxylic acid fluorescent fiber with enhanced strength prepared by in-situ wet-spinning

Chitosan grafting coumarin-3-carboxylic acid (CS-g-CCA) fiber with fluorescent function and enhanced tensile strength was successfully prepared by in-situ wet-spinning. FTIR and NMR results demonstrate that CCA is successfully grafted onto the CS molecule chains. As the grafting rate increases from 4.2 to 15.8 %, the spinning solution viscosity increases from 22 to 54 Pa·s. SEM observations show that the CS and CS-g-CCA fiber surfaces and cross-sections exhibit homogeneity and smoothness. Likewise, as the drawing ratio increases from 1.0 to 1.4, 2D WAXS patterns illustrate the molecular chain oriented significantly along the drawing direction. The CS-g-CCA fiber (the grafting rate of 15.8 %) exhibits a maximum breaking strength of 1.06 cn/dtex, increasing by 20 % more than the CS fiber. Meanwhile, it has a peak fluorescence intensity of around 480 nm. In addition, the continuous preparation process simplifies the technological route and improves the preparation efficiency of CS-g-CCA fiber. As-prepared CS-g-CCA fiber with enhanced tensile strength and elevated fluorescence efficiency lays the foundation for potential application in fluorescent probes, anti-counterfeiting, and biomedicine fields.

Multifunctional Gas and pH Fluorescent Sensors Based on Cellulose Acetate Electrospun Fibers Decorated with Rhodamine B-Functionalised Core-Shell Ferrous Nanoparticles

Ferrous core-shell nanoparticles consisting of a magnetic γ-Fe₂O₃ multi-nanoparticle core and an outer silica shell have been synthesized and covalently functionalized with Rhodamine B (RhB) fluorescent molecules (γ-Fe₂O₃/SiO₂/RhB NPs). The resulting γ-Fe₂O₃/SiO₂/RhB NPs were integrated with a renewable and naturally-abundant cellulose derivative (i.e. cellulose acetate, CA) that was processed in the form of electrospun fibers to yield multifunctional fluorescent fibrous nanocomposites. The encapsulation of the nanoparticles within the fibers and the covalent anchoring of the RhB fluorophore onto the nanoparticle surfaces prevented the fluorophore's leakage from the fibrous mat, enabling thus stable fluorescence-based operation of the developed materials. These materials were further evaluated as dual fluorescent sensors (i.e. ammonia gas and pH sensors), demonstrating consistent response for very high ammonia concentrations (up to 12000 ppm) and fast and linear response in both alkaline and acidic environments. The superparamagnetic nature of embedded nanoparticles provides means of electrospun fibers morphology control by magnetic field-assisted processes and additional means of electromagnetic-based manipulation making possible their use in a wide range of sensing applications.

Copolymer based multifunctional conducting polymer film for fluorescence sensing of glucose

A simple, rapid and effective fluorescence sensing platform has been fabricated using a fluorescent conducting polymer surface. For this purpose, a rhodamine based electroactive monomer (RDC) and a functional group containing monomer (SNS) have been copolymerized to develop a conducting polymer based sensor platform having a fluorescence and enzyme-binding surface on ITO electrode. The proposed fluorescence sensing mechanism for detection of glucose is related to the consumption of dissolved oxygen at the double layer of the electrode which is fluorescence quenching agent by glucose-GOx reaction. Concentration of glucose was investigated quantitatively from 0.05 to 1 mM via fluorescence signal measurement. This novel approach could be adapted for the production of various rapid and effective fluorescence sensing platforms for glucose.

Recent Trends in Chitosan Nanofibers: From Tissue-Engineering to Environmental Importance: A Review

Chitosan is a biodegradable, biocompatible and extracellular matrix mimicking polymer. These tunable biological properties make chitosan highly useful in a wide range of applications like tissue-engineering, wound dressing material, controlled drug delivery system, biosensors and membrane separators, and as antibacterial coatings etc. Moreover, its similarity with glycosaminoglycans makes its suitable candidate for tissue-engineering. Electrospinning is a novel technique to manufacture nanofibers of chitosan and these nanofibers possess high porosity and surface area, making them excellent candidates for biomedical applications. However, lack of mechanical strength and water insolubility make it difficult to fabricate chitosan nanofibers scaffolds. This often requires blending with other polymers and use of harsh solvents. Also, the functionalization of chitosan with different chemical moieties provides a solution to these limitations. This article reviews the recent trends and sphere of application of chitosan nanofibers produced by electrospinning process. Further, we present the latest developments in the functionalization of this polymer to produce materials of biological and environmental importance.