Ratiometric Fluorescence Probe Based on Deep-Red Emissive CdTe Quantum Dots and Eu³⁺ Hybrid for Oxytetracycline Detection

Oxytetracycline (OTC) is an environmental pollutant caused by the abuse of antibiotics, and its content in water is closely related to human health. Therefore, the development of a simple, rapid, and accurate method to detect OTC has become desirable. In this work, a ratiometric fluorescence probe based on deep red emissive CdTe quantum dots (QDs) modified by mercaptopropionic acid and Eu3+ is developed to accurately and rapidly detect OTC in water. After the addition of OTC, the photoluminescence intensity of CdTe QDs at 698 nm remains almost unchanged, while the peak at 617 nm intensifies within 40 s due to the coordination of Eu3+ with OTC. An excellent linear relationship is present between the photoluminescence intensity ratio of I617/I698 and the concentration of OTC. The limit of detection of the probe towards OCT is 5.4 nM. In addition, the probe shows good selectivity and anti-interference ability for OTC in the presence of other antibiotics, including other antibiotics, ions, and amino acids. The probe has been successfully applied to detect OTC in actual samples, demonstrating its potential for environmental application

Fe1-xS/C nanocomposites from sugarcane waste-derived microporous carbon for high-performance lithium ion batteries

We report a novel strategy to collect microporous carbon from disposable sugarcane waste for lithium ion battery (LIB) applications. First boiled in water and ethanol and then calcined, the sugarcane waste successfully transforms into microporous carbon, delivering a specific capacity of 311 mA h g<small>⁻¹</small> at 0.33C as a LIB anode material. For improved LIB performance, pyrrhotite-5T Fe<small>_{1−<em>x</em>}</small>S nanoparticles were uniformly dispersed and robustly attached to the scaffold of the microporous carbon using a novel sulfurization method. A remarkably ultrahigh capacity of 1185 mA h g<small>⁻¹</small> (well beyond the theoretical value by 576 mA h g<small>⁻¹</small>) was achieved after 200 charging/discharging cycles at a current density of 100 mA g<small>⁻¹</small>, suggesting desirable synergetic effects between Fe<small>_{1−<em>x</em>}</small>S and microporous carbon which lead to a shortened lithium ion transportation path, enhanced conductivity and effective prevention of polysulfide dissolution. Our approach opens a convenient route for mass-producing sustainable, superior LIB electrodes from natural wastes that can substitute commercial graphite

Copolythiophene-Derived Colorimetric and Fluorometric Sensor for Lysophosphatidic Acid Based on Multipoint Interactions

3-Phenylthiophene-based water-soluble copolythiophenes (<b>CPT9</b>) were designed for colorimetric and fluorometric detection of lysophosphatidic acid (LPA) based on electrostatic interaction, hydrophobic interaction, and hydrogen bonding. Other negatively charged species gave nearly no interference, and the detection limit reached to 0.6 μM, which is below the requisite detection limits for LPA in human plasma samples. The appealing performance of <b>CPT9</b> was demonstrated to originate from the multipoint interaction-induced conformational change of conjugated backbone and weakened electron transfer effect. To our best knowledge, this is the first polythiophene based optical sensor which displays emission peak red-shift followed with fluorescence enhancement

Carbon Nanoparticle-based Ratiometric Fluorescent Sensor for Detecting Mercury Ions in Aqueous Media and Living Cells

A novel nanohybrid ratiometric fluorescence sensor is developed for selective detection of mercuric ions (Hg²⁺), and the application has been successfully demonstrated in HEPES buffer solution, lake water, and living cells. The sensor comprises water-soluble fluorescent carbon nanoparticles (CNPs) and Rhodamine B (RhB) and exhibits their corresponding dual emissions peaked at 437 and 575 nm, respectively, under a single excitation wavelength (350 nm). The photoluminescence of the CNPs in the nanohybrid system can be completely quenched by Hg²⁺ through effective electron or energy transfer process due to synergetic strong electrostatic interaction and metal–ligand coordination between the surface functional group of CNPs and Hg²⁺, while that of the RhB remains constant. This results in an obviously distinguishable fluorescence color variation (from violet to orange) of the nanohybrid solution. This novel sensor can effectively identify Hg²⁺ from other metal ions with relatively low background interference even in a complex system such as lake water. The detection limit of this method is as low as 42 nM. Furthermore, the sensing technique is applicable to detect Hg²⁺ in living cells

Copolythiophene-Derived Colorimetric and Fluorometric Sensor for Visually Supersensitive Determination of Lipopolysaccharide

3-Phenylthiophene-based water-soluble copolythiophenes (CPT<b>1</b>) were designed for colorimetric and fluorometric detection of lipopolysaccharide (LPS). The sensor (CPT<b>1</b>-C) shows a high selectivity to LPS in the presence of other negatively charged bioanalytes as well an extreme sensitivity with the detection limit at picomolar level, which is the lowest ever achieved among all synthetic LPS sensors available thus far. Significantly, the sensing interaction can be apparently observed by the naked eyes, which presents a great advantage for its practical applications. The appealing performance of sensor was demonstrated to originate from the multiple electrostatic and hydrophobic cooperative interactions, synergetic with signal amplification via the conformational change of the 3-phenylthiophene-based copolymer main chain. As a straightforward application, CPT<b>1</b>-C is capable of rapidly discriminating the Gram-negative bacteria (with LPS in the membrane) from Gram-positive bacteria (without LPS)