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Antibiotic abuse is considered a serious problem affecting human health, necessitating that great attention be paid to explore robust, simple and sensitive methods for rapid evaluation. In this paper, we developed a fluorescent aptasensor for visual and real-time kanamycin detection by taking advantage of the label-free strategy based on H-aggregate disassembly of a chiral cyanine dye induced by a G-quadruplex aptamer. The good sensitivity and selectivity enabled this aptasensor to have a detection limit as low as 43 nM and have high specificity for kanamycin recognition. Furthermore, this assay was successfully applied for the detection of kanamycin in lake water and urine with excellent recoveries. [ABSTRACT FROM AUTHOR]

In this work, a new d10-configuration based Cd(II) coordination polymer (CP) with the formula [Cd2(CH3COO)2(bimb)2]·2ClO4 (1) have been synthesized using 4,4′-bis(imidazolyl)biphenyl (bimb) ligand and characterized. Single-crystal X-ray analysis reveals that the CP forms a 2D layer connected to a 3D supramolecular framework with weak packing interactions between benzyl and imidazolyl rings. CP 1 has been used as a photoluminescent sensor and a photocatalyst for the photodegradation of antibiotics, in particular nitrofurantoin (NFT). Sensing experiments indicate that 1 can selectively detect nitrofurantoin with a limit of detection of 0.025 μM, whereas when employed as a photocatalyst, CP 1 can photodecompose NFT up to 91.83% in a time span of 20 min. The decline in the photoluminescence intensity of CP 1 in the presence of NFT and the photocatalytic mechanism are addressed using theoretical calculations. [ABSTRACT FROM AUTHOR]

A fluorescent probe based on single metal–organic framework material without additional fluorophores and active sites can significantly improve the stability of the probe for detection, and has very important application value in environmental analysis and detection. In this paper, a simple and rapid fluorescence detection method was established with Zn-MOF, which realized the highly sensitive detection of tetracycline antibiotics and NH4+ in water. The prepared Zn-MOF has abundant pores and can exist stably in water. When tetracycline antibiotics are present in Zn-MOF aqueous solution, based on the unique coordination ability between Zn and N, tetracycline antibiotics rich in N will be adsorbed into the pore canals of MOF, and aggregation-induced luminescence will occur. The original non-fluorescent Zn-MOF will immediately produce yellow fluorescence, realizing the detection of tetracycline antibiotics in water, with the limit of detection reaching 0.017 μM in a linear range of 0.02–13 μM. Zn-MOF is further used for the detection of tetracycline antibiotics in actual samples of milk and honey. Oxytetracycline (OTC) with the best fluorescence response of tetracycline antibiotics was coated on Zn-MOF to synthesize OTC@Zn-MOF fluorescent probe. NH4+ will replace the original ligand of Zn-MOF, which will disintegrate MOF and release OTC, resulting in a fluorescence decrease. Therefore, NH4+ can be detected with low limit of detection (0.038 μM) in a linear range of 0 to 3 mM. The probe is expected to be able to detect ammonia in the environment. [ABSTRACT FROM AUTHOR]

Immunochromatographic assay (ICA) has attracted increasing attention in antibiotic detection. Driven by global sustainability and environmentalism goals, green and sustainable detection strategies are in high demand. Inspired by the characteristics of natural dyes and their wide-ranging application scenarios, we excavated natural plant-extracted alizarin as a novel synthetic-free label for ICA (NAST-ICA) to meet the challenges. By regulating the proportions of ethanol/water solution, the dissolution of alizarin was optimized, ensuring the protection of antibody activity and color rendering of alizarin labels, and achieving the stability of sensitive detection performance. The rich functional groups endow alizarin tags with the ability to be directly incorporated into antibodies within 5 min to form efficient and stable detection probes. As a proof of concept, NAST-ICA showed a limit of detection (LOD) of 1.69 ng mL-1 for streptomycin. More importantly, the reliability of the actual detection application scenario was verified: realizing acceptable total recoveries of 87.17-123.85% and RSD values of 1.99-3.64% in spiked milk, honey, and actual water samples. The proposed nature-derived synthetic-free signal tracer assay demonstrated an efficient and stable detecting strategy for antibiotics, paving a green way for ICA applications. [ABSTRACT FROM AUTHOR]

Currently, the uncontrolled intake and slow metabolic rate of nearly all antibiotics have led to serious health problems and environmental threats. Among the frequently used β-lactam antibiotics, amoxicillin (AMX) is still the highest in terms of consumption rate. Even a trace amount of AMX can have serious harmful effects on human health and aquatic life. In this work, we wish to report a facile synthesis of poly(pyrogallol)-based highly green-emissive carbon dots via a reflux method and their application in the fluorescent detection of AMX. The pyrogallol-derived carbon dots (PC dots) exhibit high water solubility and stability. They exhibit an emission band at 420 nm upon excitation at 310 nm. Under the optimum sensing conditions, the emission intensity decreases on adding the AMX drug. Based on the change in the emission intensity, the concentration of AMX was calculated. Good linearity was obtained from 2.49 to 45.5 μM AMX, and the detection limit (LOD) was found to be 9.2 nM (LOD = 3 S m−1). Finally, the sensor system was applied for the detection of AMX in clinical samples. [ABSTRACT FROM AUTHOR]

A novel Cd-based MOF fluorescent sensor [(Cd)2O(BIMB)0.5(BTB)] [CUST-580, H3BTB = 1,3,5-tris(4-carboxyphenyl)benzene, BIMB = 1,4-bis((1H-imidazol-1-yl) methyl)benzene] was successfully synthesized under solvothermal conditions. Due to the unique 3D spatial structure and pores, a methyl blue@CUST-580 composite with double emission was synthesized by soaking methyl blue dye molecules. Further studies showed that CUST-580 detected the antibiotic nitrofurantoin (NFT) to the ppb level. Compared with CUST-580, methyl blue@CUST-580 exhibited higher fluorescence emission as well as sensitive fluorescence quenching activities in response to NFT with detection limits as low as 3.3 ppb. In addition, the observed fluorescence response of the composites to NFT was highly stable and reversible after the recovery experiments. [ABSTRACT FROM AUTHOR]

Two coordination polymers, namely {[Cd3(TIYM)2(5-SASS)2(H2O)2]·H2O}n (1) and {[Zn2(TIYM)(5-SASS)(μ2-OH)]·5H2O}n (2), were assembled using a mixed ligand strategy with the semi-rigid linker tetrakis(imidazol-1-ylmethyl)methane (TIYM) and 5-sulfoisophthalic acid sodium salt (5-SASS). Luminescence studies reveal that compounds 1 and 2 show strong fluorescence and exhibit efficient luminescence quenching in detecting UO22+ cations, Cr2O72−/CrO42− anions, and the NFT antibiotic in aqueous media, and can thus serve as promising sensors. The detection limits of compounds 1–2 are 1.96 × 10−4/1.36 × 10−4 M for UO22+ cations, 6.53 × 10−5/5.41 × 10−5 M for Cr2O72− anions, 2.29 × 10−4/1.04 × 10−4 M for CrO42− anions, and 5.62 × 10−5/4.74 × 10−5 M for the NFT antibiotic, respectively, indicating that the two CPs are promising multi-functional luminescent sensors. Additionally, the possible mechanisms for luminescence quenching have been investigated using spectral overlap experiments and DFT calculations. [ABSTRACT FROM AUTHOR]

Here we present the hydrothermal synthesis of nitrogen-doped carbon quantum dot (N-CQD) decorated gadolinium oxide (N-CQD@Gd2O3) nanocomposite for the first time. The nanocomposite features a nanoseed-like structure rather than the typical Gd2O3 nanorod-like structure. The presence of N-CQDs plays a dynamic role in the specific structural formation of the nanocomposite, which has been evaluated through physiochemical characterizations. Also, for the first time, the nanocomposite was employed as an electrode material for the sensitive electrochemical detection of an antibiotic drug, clioquinol (CQL), using an amperometric technique. Based on the oxidation peak current response of CQL, the influence of experimental factors such as the nanocomposite loading concentration/volume, scan rate, sample concentration, and accumulation time were investigated. As a consequence, the developed N-CQD@Gd2O3/GCE sensor exhibits a low detection limit of 2.1 nM and a high sensitivity of 3.6 μA μM−1 cm−2 for the detection of CQL. Furthermore, the developed sensor has a high level of stability, repeatability, and reproducibility. Furthermore it performed well in real sample analysis with good recovery results, suggesting its practical applicability. [ABSTRACT FROM AUTHOR]