Search Results (2,105)

Metal nanoclusters (NCs) are promising alternatives to organic dyes and quantum dots. These NCs exhibit unique physical and chemical properties, such as fluorescence, chirality, magnetism and catalysis, which contribute to significant advancements in biosensing, biomedical diagnostics and therapy. Through adjustments in composition, size, chemical environments and surface ligands, it is possible to create NCs with tunable optoelectronic and catalytic activity. This review focuses on the integration of aptamers with metal NCs, detailing molecular detection strategies that utilise the effect of aptamers on optical signal emission of metal NC-based biosensing systems. This review also highlights recent advancements in biosensing and biomedical applications, as well as illustrative case studies. To conclude, the strengths, limitations, current challenges and prospects for metal NC-based systems were examined. Full article

Methylene blue is a cationic organic dye commonly found in wastewater, groundwater, and surface water due to industrial discharge into the environment. This emerging pollutant is notably persistent and can pose risks to both human health and the environment. In this study, we developed a Surface Plasmon Resonance Biosensor employing a BK7 prism coated with 3 nm chromium and 50 nm of gold in the Kretschmann configuration, specifically for the detection of methylene blue. For the first time, laccases immobilized on a gold surface were utilized as bio-receptors for this organic dye. The enzyme was immobilized using carbodiimide bonds with EDC/NHS crosslinkers, allowing for the analysis of samples with minimal preparation. The method demonstrated validation with a limit of detection (LOD) of 4.61 mg L⁻¹ and a limit of quantification (LOQ) of 15.37 mg L⁻¹, a working range of 0–100 mg L⁻¹, and an R² value of 0.9614 during real-time analysis. A rainwater sample spiked with methylene blue yielded a recovery rate of 122.46 ± 4.41%. The biosensor maintained a stable signal over 17 cycles and remained effective for 30 days at room temperature. Full article

Cyclodextrins (CDs) are natural cyclic oligosaccharides with the ability to form inclusion complexes with various organic substances. In this paper, we investigate the potential of CD complex formation to enhance the antibacterial activity and antioxidant properties of poorly soluble bioactive agents, such as chalcones, chromenes, stilbenoids and xanthylium derivatives, serving as potential adjuvants, in comparison with standard antiseptics. The interaction of these bioactive agents with the hydrophobic pocket of methyl-β-cyclodextrin (MCD) was confirmed using spectroscopic methods such as UV-vis, FTIR, ¹H and ¹³C NMR, mass-spectrometry. CD-based delivery system allows for combining multiple active agents, improving solubility, antibacterial efficacy by enhancing penetration into target bacterial cells (E. coli selectivity demonstrated via confocal microscopy). Novel compounds of chalcones and stilbenoids derivatives additionally enhance efficacy by inhibiting bacterial efflux pumps, increasing membrane permeability, and inhibiting bacterial enzymes, and showed a synergy when used in combination with metronidazole. The intricate relationship between the structural characteristics and functional properties of chalcones and stilbenoids in terms of their antibacterial and antioxidative capabilities is revealed. The substituents within aromatic rings significantly influence this activity, where position of electron-donating methoxy groups playing a crucial role. Among chalcones, stilbenoids, ana xanthyliums, the compounds caring a benzodioxol ring, analogous to natural bioactive compounds like apiol, dillapiol, and myristicin, emerge as prominent antibacterial activity. To explore the possibility to create theranostic formulations, we used fluorescent markers to visualize target cells, antiseptics to provide antibacterial activity, and bioactive agents as chalcones acting as adjuvants. Additionally, new antioxidant compounds were found such as Xanthylium derivative (R351) and chromene derivative: 1-methyl-3-(2-amino-3-cyano-7-methoxychromene-4-yl)-pyridinium methanesulfate: the pronounced antioxidant properties of these substances are observed comparable to quercetin in the efficiency. Rhodamine 6G, gentian violet, and Congo Red exhibit good antioxidant properties, although their activity is an order of magnitude lower than that of quercetin. However, they have remarkable potential due to their multifaceted nature, including the ability to visualize target cells. The most effective theranostic formulation is the combination of the antibiotic (metronidazole) + dye/fluorophore (methylene blue/rhodamine 6G) for visualization of target cells + adjuvant (chalcones or xanthylium derivatives) for antiinflammation effect. This synergistic combination, results in a promising theranostic formulation for treating bacterial infections, with enhanced efficiency, selectivity and minimizing side effects. Full article

Molecular dyes containing carbazole-based $\pi$ bridges and/or julolidine-based donors should be promising molecules for intense SWIR emission with potential application to molecular bioimaging. This study stochastically analyzes the combinations of more than 250 organic dyes constructed within the D-$\pi$-D (or equivalently D-B-D) motif. These dyes are built from 22 donors (D) and 14 $\pi$ bridges (B) and are computationally examined using density functional theory (DFT). The DFT computations provide optimized geometries from which the excited state transition wavelengths and associated oscillator strengths and orbital overlaps are computed. While absorption is used as a stand-in for emission, the longer the absorption wavelength, the longer the emission should be as well for molecules of this type. Nearly 100 novel dyes reported in this work have electronic absorptions at or beyond 1200 nm, opening the possibility for future synthesis and experimental characterization of new molecular dyes with promising properties for bioimaging. Full article

Near-infrared light-triggered photocatalytic water treatment has attracted significant attention in recent years. In this novel research, rational sonochemical fabrication of Ag₂S/g-C₃N₄ nanocomposites with various compositions of Ag₂S (0–25) wt% was carried out to eliminate hazardous rhodamine B dye in a cationic organic pollutant model. g-C₃N₄ sheets were synthesized via controlled thermal annealing of microcrystalline urea. However, black Ag₂S nanoparticles were synthesized through a precipitation-assisted sonochemical route. The chemical interactions between various compositions of Ag₂S and g-C₃N₄ were carried out in an ultrasonic bath with a power of 300 W. XRD, PL, DRS, SEM, HRTEM, mapping, BET, and SAED analysis were used to estimate the crystalline, optical, nanostructure, and textural properties of the solid specimens. The coexistence of the diffraction peaks of g-C₃N₄ and Ag₂S implied the successful production of Ag₂S/g-C₃N₄ heterojunctions. The band gap energy of g-C₃N₄ was exceptionally reduced from 2.81 to 1.5 eV with the introduction of 25 wt% of Ag₂S nanoparticles, implying the strong absorbability of the nanocomposites to natural solar radiation. The PL signal intensity of Ag₂S/g-C₃N₄ was reduced by 40% compared with pristine g-C₃N₄, implying that Ag₂S enhanced the electron–hole transportation and separation. The rate of the photocatalytic degradation of rhodamine B molecules was gradually increased with the introduction of Ag₂S on the g-C₃N₄ surface and reached a maximum for nanocomposites containing 25 wt% Ag₂S. The radical trapping experiments demonstrated the principal importance of reactive oxygen species and hot holes in destroying rhodamine B under natural solar radiation. The charge transportation between Ag₂S and g-C₃N₄ semiconductors proceeded through the type I straddling scheme. The enriched photocatalytic activity of Ag₂S/g-C₃N₄ nanocomposites resulted from an exceptional reduction in band gap energy and controlling the electron–hole separation rate with the introduction of Ag₂S as an efficient photothermal photocatalyst. The novel as-synthesized nanocomposites are considered a promising photocatalyst for destroying various types of organic pollutants under low-cost sunlight radiation. Full article

In recent years, nanomaterials have gained special attention for removing contaminants from wastewater. Nanoparticles (NPs), such as carbon-based materials and metal oxides, exhibit exceptional adsorption capacity and antimicrobial properties for wastewater treatment. Their unique properties, including reactivity, high surface area, and tunable surface functionalities, make them highly effective adsorbents. They can remove contaminants such as organics, inorganics, pharmaceuticals, medicine, and dyes by adsorption mechanisms. In this review, the effectiveness of different types of carbon-based NPs, including carbon nanotubes (CNTs), graphene-based nanoparticles (GNPs), carbon quantum dots (CQDs), carbon nanofibers (CNFs), and carbon nanospheres (CNSs), and metal oxides, including copper oxide (CuO), zinc oxide (ZnO), iron oxide (Fe₂O₃), titanium oxide (TiO₂), and silver oxide (Ag₂O), in the removal of different contaminants from wastewater has been comprehensively evaluated. In addition, their synthesis methods, such as physical, chemical, and biological, have been described. Based on the findings, CNPs can remove 75 to 90% of pollutants within two hours, while MONPs can remove 60% to 99% of dye in 150 min, except iron oxide NPs. For future studies, the integration of NPs into existing treatment systems and the development of novel nanomaterials are recommended. Hence, the potential of NPs is promising, but challenges related to their environmental impact and their toxicity must be considered. Full article

The design of multi-purpose decontaminants with environmentally friendly characteristics, low cost, and high efficiency in removing pollutants from the environment is an effective and economic strategy for maintaining the long-term development of the ecosystem. Based on the strategy of killing two birds with one stone, an egg white (EW)/TiO₂ hydrogel with a porous structure is devised as a bio-adsorbent using waste eggs nearing their expiration date for simultaneously achieving the efficient removal of organic dyes and the inactivation of microorganisms from industrial wastewater. The characterizations of its morphology and composition using scanning electron microscopy (SEM), the Brunauer–Emmett–Teller (BET) theory, energy-dispersive spectrometry (EDS), Fourier transform infrared spectroscopy (FTIR), and a thermogravimetric analyzer (TGA) validate the successful synthesis of EW/TiO₂. The maximum adsorption capacity of EW/TiO₂ is 333.172 mg∙mL⁻¹ according to the Langmuir model. The photodegradation of a methyl blue (MB) solution under irradiation via a xenon lamp is used to assess the photocatalytic behavior of EW/TiO₂. Among the different samples, the 5 wt% TiO₂-doped EW/TiO₂ hydrogel shows an efficiency of 99% for 120 min of irradiation. Finally, the antibacterial properties of the EW/TiO₂ hydrogel are evaluated by calculating its bacterial survival rate against Escherichia coli (E. coli). The EW/TiO₂ photocatalyst exhibits a photocatalytic inactivation efficiency of 90.4%, indicating that the EW/TiO₂ hydrogel possesses positive antibacterial activity via effectively inhibiting the growth of the bacteria, which is suitable for industrial wastewater treatment over a long period of time. Full article

Aguama (Bromelia pinguin L.), a plant belonging to the Bromeliaceae family, possesses a rich content of organic compounds historically employed in traditional medicine. This research focuses on the sustainable synthesis of ZnO nanoparticles via an eco-friendly route using 1, 2, and 4% of Aguama peel extract. This method contributes to environmental sustainability by reducing the use of hazardous chemicals in nanoparticle production. The optical properties, including the band gap, were determined using the TAUC model through Ultraviolet–Visible Spectroscopy (UV–Vis). The photocatalytic activity was evaluated using three widely studied organic dyes (methylene blue, methyl orange, and rhodamine B) under both solar and UV radiation. The results demonstrated that the ZnO nanoparticles, characterized by a wurtzite-type crystalline structure and particle sizes ranging from 68 to 76 nm, exhibited high thermal stability and band gap values between 2.60 and 2.91 eV. These nanoparticles successfully degraded the dyes completely, with methylene blue degrading in 40 min, methyl orange in 70 min, and rhodamine B in 90 min. This study underscores the potential of Bromelia pinguin L. extract in advancing sustainable nanoparticle synthesis and its application in environmental remediation through efficient photocatalysis. Full article

Drinking and wastewater are to be treated for safe human consumption and for keeping surface waters clean. There are multiple water purification procedures, but the use of ion-exchange resins significantly enhances water purification efficiency. This review was targeted on highlighting the concept and classification of polymeric ion-exchange resins as well as pointing out their real-world applications. Their successful use for purification purposes has been linked to their chemical structure, simplicity of operation, accessibility, and reusability. Therefore, polymeric ion-exchange resins have been used for the removal of a wide range of organic and inorganic pollutants such as pharmaceutical compounds, dyes, organic matter, metals, and many others. Ion-exchange resins are obtained directly by synthesis methods or grafting ionizable groups on polymer matrix in order to ensure continuous improvement. Furthermore, the newly designed ion-exchange resins take into consideration biodegradability potential towards obtaining ecofriendly compounds. Full article

Nanomaterials have attracted significant attention as signal reporters for immunoassays. They can directly generate detectable signals or release a large number of signaling elements for readout. Among various nanolabels, nanomaterials composed of multiple signaling molecules have shown great potential in immunoassays. Generally, signaling molecules can be entrapped in nanocontainers or self-assemble into nanostructures for signal amplification. In this review, we summarize the advances of signaling molecules-entrapped or assembled nanomaterials for colorimetric and fluorescence immunoassays. The nanocontainers cover liposomes, polymers, mesoporous silica, metal–organic frameworks (MOFs), various nanosheets, nanoflowers or nanocages, etc. Signaling molecules mainly refer to visible and/or fluorescent organic dyes. The design and application of immunoassays are emphasized from the perspective of nanocontainers, analytes, and analytical performances. In addition, the future challenges and research trends for the preparation of signaling molecules-entrapped or assembled nanolabels are briefly discussed. Full article

The oxidation of organic pollutants in water is the most reported application of a Titanium dioxide (TiO₂) photocatalyst. During the last decade, photoreduction with TiO₂ has also been explored but simultaneous capabilities for unmodified TiO₂ have not been reported yet. Here, we reported on the fabrication of TiO₂ nanorods using hydrothermal treatment and compared the effect of two different TiO₂ powders as the starting material: P-25 and TiO₂ sol–gel (N-P25 and N-TiO₂, respectively) which were further calcined at 400 °C (N-P25-400 and N-TiO₂-400). XPS and XRD analyses confirmed the presence of sodium and hydrogen titanates in N-P25, but also an anatase structure for N-TiO₂. The specific surface area of the calcined samples decreased compared to the dried samples. Photocatalytic activity was evaluated using phenol and methyl orange for degradation, whereas 4-nitrophenol was used for photoreduction. Irradiation of the suspension was performed under UV light (λ = 254 nm). The results demonstrated that the nanorods calcined at 400 °C were more photoactive since methyl orange (20 ppm) degradation reached 86% after 2 h, when N-TiO₂-400 was used. On the other hand, phenol (20 ppm) was completely degraded by the presence of N-P25-400 after 2 h. Photoreduction of 4-nitrophenol (5 ppm) was achieved by the N-TiO₂-400 during the same period. These results demonstrate that the presence of Ti³⁺ and the source of TiO₂ have a significant effect on the photocatalytic activity of TiO₂ nanorods. Additionally, the removal of methylene blue (20 ppm) was performed, demonstrating that N-TiO₂ exhibited a high adsorption capacity for this dye. Full article

With the increasing demand for eco-friendly water treatment solutions, the development of novel photocatalysts such as calcium polyanion (Ca-POM) plays a vital role in mitigating industrial wastewater pollution. In this research, calcium polyanion, H₆₀N₆Na₂Ca₂W₁₂O₆₀ (Ca–POM), was successfully synthesized via a self-assembly reaction from metal-oxide subunits. The synthesized Ca–POM was verified to have a polycrystalline structure with a broad size distribution, with an average particle diameter of approximately 623.62 nm. Powder X-ray diffraction (XRD) analysis confirmed the polycrystalline structure of the Ca–POM, with a calculated band gap energy of 3.29 eV. The photocatalytic behavior of the Ca-POM sample was tested with two model dyes, methylene blue (MB) and methyl orange (MO). The reaction mixture was then exposed to ultraviolet (UV) irradiation for durations ranging from 20 to 140 min. The synthesized cluster demonstrated photocatalytic efficiency (PCE%) values of 81.21% for MB and 25.80% for MO. This work offers a valuable basis for applying Ca–POM as a heterogeneous photocatalyst for treating industrial wastewater organic pollutants and highlights the potential of Ca–POM in sustainable water treatment applications. Full article

Implementing greener approaches is a sustainable and eco-friendly methodology for nanocomposite synthesis. This work reports the sustainable fabrication of Fe-doped ZnS (Fe_0.3Zn_0.7S) nanocomposite and its broad-spectrum applications. The systematic characterization was carried out using several advanced analytical techniques. DLS, Zeta potential, SEM, XPS, and TEM performed morphological and size assessments of the engineered nanocomposite. Eventually, XRD provided valuable insights into the crystalline behavior of nanocomposite. The nanocomposites were then treated against the organic dye Safranin O, which displayed 93% degradation within an hour with the rate constant value of 0.0326 min⁻¹. Parameters influencing the percentage degradation, such as temperature, pH, etc., were also discussed. Moreover, an LCMS test was also conducted to evaluate the presence of reactive intermediates. Safranin O’s degradation was confirmed by identifying intermediate products, such as compounds with m/z values of 335.84, 321.81, 306.79, 292.77, and 257.32, which were indicative of progressive dye breakdown. Finally, the photocatalytic enactment examination verified that the prepared nanocomposite’s nitrogen fixation rate (38.96 µmolg⁻¹) was way greater (~4 times) than the pristine compound. In addition, prepared nanoparticles demonstrated a befitting ability to eliminate a wide range of threatening pathogenic fungi. The doping of Fe into ZnS further enhanced the inhibition against Fusarium oxysporum. Full article

In this work, the mechanical properties of hydrogels based on linear polyethyleneimine (PEI) chemically crosslinked with ethyleneglycoldiglycidyl ether (EGDE) were improved by the ionic crosslinking with sodium tripolyphosphate (TPP). To this end, the quaternization of the nitrogen atoms present in the PEI structure was conducted to render a network with a permanent positive charge to interact with the negative charges of TPP. The co-crosslinking process was studied by ¹H high-resolution magic angle spinning (¹H HRMAS) NMR and X-ray photoelectron spectroscopy (XPS) in combination with organic elemental analysis and inductively coupled plasma mass spectrometry (ICP-MS). In addition, the mobility and confinement of water molecules within the co-crosslinked hydrogels were studied by low-field ¹H NMR. The addition of small amounts of TPP, 0.03 to 0.26 mmoles of TPP per gram of material, to the PEI-EGDE hydrogel resulted in an increase in the deformation resistance from 320 to 1080%, respectively. Moreover, the adsorption capacity of the hydrogels towards various emerging contaminants remained high after the TPP crosslinking, with maximum loading capacities (q_max) of 77, 512, and 55 mg g⁻¹ at pH = 4 for penicillin V (antibiotic), methyl orange (azo-dye) and copper(II) ions (metal ion), respectively. A significant decrease in the adsorption capacity was observed at pH = 7 or 10, with q_max of 356 or 64 and 23 or 0.8 mg g⁻¹ for methyl orange and penicillin V, respectively. Full article

Many semiconductor photocatalysts are characterized by high photostability and non-toxicity but suffer from the limited excitation in the UV part of the spectrum and the fast recombination of the photogenerated electron–hole pairs. To improve the above properties, biochar-supported composite photocatalysts have recently attracted much attention. Compared with the pure photocatalyst, the biochar-enriched catalyst has superior specific surface area and high porosity, catalytic efficiency, stability, and recoverability. Biochar can be obtained from various carbon-rich plant or animal wastes by different thermochemical processes such as pyrolysis, hydrothermal carbonization, torrefaction, and gasification. The main features of biochar are its low price, non-toxicity, and the large number of surface functional groups. This paper systematically presents the latest research results on the method of preparation of various composites in terms of the choice of photoactive species and the source of biomass, their physico-chemical properties, the mechanism of the photocatalytic activity, and degradation efficiency in the treatment of organic contaminants (dyes and antibiotics) in an aquatic environment. Particular emphasis is placed on understanding the role of biochar in improving the photocatalytic activity of photoactive species. Full article