Green Carbon Dots from Pinecones and Pine Bark for Amoxicillin and Tetracycline Detection: A Circular Economy Approach

Over the years, the abuse of antibiotics has increased, leading to their presence in the environment. Therefore, a sustainable method for detecting these substances is crucial. Researchers have explored biomass-based carbon dots (CDs) to detect various contaminants, due to their low cost, environmental friendliness, and support of a circular economy. In our study, we reported the synthesis of CDs using pinecones (PCs) and pinebark (PB) through a sustainable microwave method. We characterized the PCCDs and PBCDs using X-ray diffraction, Raman spectroscopy, Transmission Electron Microscope, and Fourier transform infrared, Ultraviolet-visible, and photoluminescence (PL) spectroscopy. The PCCDs and PBCDs were tested for the detection of amoxicillin (AMX) and tetracycline (TC). The results indicated that the sizes of the PCCDs and PBCDs were 19.2 nm and 18.39 nm, respectively, and confirmed the presence of the 002 plane of the graphitic carbon structure. They exhibited excitation wavelength dependence, good stability, and quantum yields ranging from 6% to 11%. PCCDs and PBCDs demonstrated "turn-off" detection for TC and AMX. The limits of detection (LOD) for TC across a broader concentration range were found to be 0.062 µM for PCCDs and 0.2237 µM for PBCDs. For AMX detection, PBCDs presented an LOD of 0.49 µM.

Repurposing doxycycline for Alzheimer's treatment: Challenges from a nano-based drug delivery perspective

Drug repurposing, also known as drug repositioning, involves identifying new applications for drugs whose effects in a disease are already established. Doxycycline, a broad-spectrum antibiotic belonging to the tetracycline class, has demonstrated potential activity against neurodegenerative diseases like Alzheimer's and Parkinson's. However, despite its promise, the repurposed use of doxycycline encounters challenges in reaching the brain in adequate concentrations to exert its effects. To address this issue, nanostructured systems offer an innovative approach that can enhance brain targeting and the desired therapeutic outcomes. This review discusses the advances in doxycycline repurposing for Alzheimer's disease, presenting physicochemical and biological aspects that permeate doxycycline's repositioning and its application in nano-based delivery systems.

Smartphone-assisted portable swabs for blood glucose management: A point-of-use assay for dual-mode visual detection based on bifunctional carbon dots

Controlling glucose (Glu) intake is a "required course" for diabetics, thus quickly and precisely measuring the amount of Glu in food is crucial. For this purpose, a novel smartphone-assisted portable swab for the dual-mode visual detection of Glu was constructed combined the selectivity of natural enzymes with the controllable catalytic activity of nanozymes. Glu was specifically decomposed by glucose oxidase (natural enzyme) to produce H2O2, which was catalyzed by carbon dots (FeMn/N-CDs, nanozyme) to accelerate the reaction of o-phenylenediamine (OPD, colorless) to produce 2,3-diaminophenazine (DAP, yellow). As a result, the absorbance at 450 nm gradually increased with the increasing concentration of Glu, leading to a color change in the system from colorless to yellow. Meanwhile, the fluorescence of FeMn/N-CDs gradually decreased at 450 nm, while the fluorescence of DAP gradually increased at 550 nm, allowing for both ratiometric fluorescence and colorimetric dual-mode detection. Furthermore, natural enzyme and nanozyme together with OPD were co-loaded on the swabs to achieve cascade catalysis of Glu. The assembled portable swabs have detection ranges of 1-600 μM (LOD = 0.37 μM) and 4-1200 μM (LOD = 1.19 μM) for the colorimetric and fluorometric detection, respectively. The field test results on real samples demonstrated that the portable swabs have great promise for use in efficiently and accurately guiding the dietary intake of diabetics.

Fabrication of a Terbium-Functionalized Cadmium Organic Framework with Proper Energy Levels as a Ratiometric Probe of an Anthrax Biomarker

Anthrax bacillus is a very dangerous zoonotic pathogen that seriously endangers public health. Rapid and accurate qualitative and quantitative detection of its biomarkers, 2,6-dipicolinic acid (DPA), is crucial for the prevention and treatment of this pathogenic bacterium. In this work, a novel Cd-based MOF (TTCA-Cd) has been synthesized from a polycarboxylate ligand, [1,1':2',1″-terphenyl]-4,4',4″,5'-tetracarboxylic acid (H4TTCA), and further doped with Tb(III), forming a dual-emission lanthanide-functionalized MOF hybrid (TTCA-Cd@Tb). TTCA-Cd@Tb can be developed as a high-performance ratiometric fluorescent sensor toward DPA with a very low detection limit of 7.14 nM and high selectivity in a wide detection range of 0-200 μM, demonstrating a big advancement and providing a new option for the detection of DPA.

Glutathione-Mediated Synthesis of WO3 Nanostructures with Controllable Morphology/Phase for Energy Storage, Photoconductivity, and Photocatalytic Applications

Developing an improved synthesis method that controls the morphology and crystal phase remains a substantial challenge. Herein, we report phase and morphology-controlled hydrothermal synthesis of tungsten oxides by varying acid concentration and utilizing glutathione (GSH) as a structural directing agent, together with the exploration of their applications in supercapacitors, photoconductivity, and photocatalysis. Orthorhombic hydrated tungsten oxide (WO3·0.33H2O) with nonuniform block and plate-like morphology was obtained at 3 M hydrochloric acid (HCl). In contrast, nonhydrated monoclinic tungsten oxide (WO3) with smaller rectangular blocks was obtained at 6 M HCl. Further, the addition of GSH results in an increase in the surface area of the materials along with a narrowing of the band gap. Moreover, it plays a pivotal role in regulating the morphology through oriented attachments, Ostwald ripening, and the self-assembly of WO3 nuclei. GHTO and GTO polymorphs showed pseudocapacitive behavior with the highest specific capacitances of 450 and 300 F g-1 at 0.5 A g-1, maintaining 94 and 92% retention stability, respectively, over 1000 cycles at 2 A g-1. Also, the synthesized materials displayed favorable photoconductivity under light irradiation, implying potential utilization in photovoltaic applications. Moreover, these materials exhibited remarkable photocatalytic performance in the degradation of methylene blue (MB) dye, establishing themselves as highly effective photocatalysts. Therefore, nanostructured tungsten oxide showcases its versatility, rendering it an appealing candidate for energy storage, photovoltaic systems, and photocatalysis.

Highlights in Interface of Wastewater Treatment by Utilizing Metal Organic Frameworks: Purification and Adsorption Kinetics

Polluted water has become a concern for the scientific community as it causes many severe threats to living beings. Detection or removal of contaminants present in wastewater and attaining purity of water that can be used for various purposes are a primary responsibility. Different treatment methods have already been used for the purification of sewage. There is a need for low-cost, highly selective, and reusable materials that can efficiently remove pollutants or purify contaminated water. In this regard, MOFs have shown significant potential for applications such as supercapacitors, drug delivery, gas storage, pollutant adsorption, etc. The outstanding structural diversity, substantial surface areas, and adjustable pore sizes of MOFs make them superior candidates for wastewater treatment. This Review provides an overview of the interaction science and engineering (kinetic and thermodynamic aspects with interactions) underpinning MOFs for water purification. First, fundamental strategies for the synthesis methods of MOFs, different categories, and their applicability in wastewater treatment are summarized, followed by a detailed explanation of various interaction mechanisms. Finally, current challenges and future outlooks for research on MOF materials toward the adsorption of hazardous components are discussed. A new avenue for modifying their structural characteristics for the adsorption and separation of hazardous materials, which will undoubtedly direct future work, is also summarized.

Metal-doped carbon dots as robust nanomaterials for the monitoring and degradation of water pollutants

The contamination of the environment by domestic and industrial discharges is a relevant and persistent problem that needs novel solutions. Innovations in the detection, adsorption, and removal or in-situ degradation of toxic components are urgently required. Various effective techniques and materials have been proposed to address this problem, in which carbon dots (CDs) stand out because of their unique properties and low-cost and abundant nature. Their combination with different metals results in the enhancement of their innate properties. Metal-doped CDs have shown excellent results and competitive advantages in recent times. Considering the above useful critiques and CDs notable potentialities, this review discusses different approaches in detail to sense, adsorb, and photodegrade different pollutants in water samples. It was found that altering the electronic structure of CDs via metal doping has a great potential to enhance the optical, electrical, chemical, and magnetic capabilities of CDs, which in turn is beneficial for wastewater treatment.

Naproxen release from carbon dot coated magnetite nanohybrid as versatile theranostics for HeLa cancer cells

Nanohybrid magnetite carbon dots (Fe₃O₄@CDs) were successfully synthesized to improve their applicability in multi-response bioimaging. The nanohybrid was prepared via pyrolysis and further loaded with naproxen (NAP) to promote drug delivery features. The characterization of the synthesized Fe₃O₄@CDs demonstrated the existence of Fe₃O₄ crystals by matching with JCPDS 75-0033 and its narrow size distribution at 11.30 nm; further, FTIR spectra confirmed the presence of Fe–O groups, C–O stretching, C–H sp², and C–O bending, along with dual-active fluorescence and magnetic responses. The nanohybrids also exhibit particular properties such as a maximum wavelength of 230.5 nm, maximum emission in the 320–420 nm range, and slight superparamagnetic reduction (Fe₃O₄: 0.93620 emu per g; Fe₃O₄@CDs: 0.64784 emu per g). The cytotoxicity assessment of the nanohybrid revealed an excellent half-maximal inhibitory concentration (IC₅₀) of 17 671.5 ± 1742.6 μg mL⁻¹. Then, the incorporation of NAP decreased the cell viability to below 10%. The kinetic release properties of NAP are also confirmed as pH-dependent, and they follow the Korsmeyer–Peppas kinetics model. These results indicated that the proposed Fe₃O₄@CDs can be used as a new model for theranostic treatment.

Nanohybrid magnetite carbon dots (Fe₃O₄@CDs) were successfully synthesized to improve their applicability in multi-response bioimaging.