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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]

With the high output and large use of antibiotics in the process of aquaculture, pollution caused by antibiotics in water environments is becoming a thorny problem, and its ecological risk has aroused widespread concern. In this work, the lanthanide hybrid material Eu@ZIF-90–PA is synthesized by a two-step post synthesis strategy using ZIF-90 with a modifiable group as a parent skeleton. Owing to its luminescence properties and water stability, the lanthanide functionalized material can be utilized as a novel "turn-on" fluorescent probe for quantitative detection of flumequine in water environments. Additionally, the probe can not only be reused, but also quickly respond to flumequine within 30 s and the detection limit is 0.24 ppm. Even in the complex river water, the probe still exhibits an obvious luminescence enhancement effect with flumequine, which provides an efficient and convenient method for the detection of flumequine in real water. Finally, the fluorescence enhancement mechanism between flumequine and the probe is further explored. [ABSTRACT FROM AUTHOR]

One NIR luminescent 14-metal Nd(III) nanoring (1, molecular size: 1.0 × 2.2 × 2.6 nm) was obtained from a rigid tridentate ligand, which can absorb and transfer light energy to the Nd(III) ions. 1 shows interesting luminescence sensing activity to antibiotics, in particular to NFAs with high sensitivity due to the inner filter effect. The quenching constants and the limits of detection of 1 to NFAs are 1.05 × 104 M−1–2.33 × 104 M−1 and 3.05 μM–6.75 μM, respectively. The high fluorescence sensitivities of 1 to NFAs are not changed by the existence of other antibiotics. It also exhibits high sensitivity in the luminescent detection of NFAs contained in real antibiotic drugs. [ABSTRACT FROM AUTHOR]

Herein, we report a Fe3O4@polydopamine (PDA) nanocomposite and exonuclease III (Exo III)-assisted homogeneous fluorescence biosensing method for ultrasensitive detection of kanamycin (Kana) antibiotic. A hairpin DNA containing the Kana-aptamer sequence (HP) was first designed for the highly specific biorecognition of the target analyte. Because of the aptamer biorecognition-induced structural change of HP and the highly effective catalyzed reaction of Exo III, a large amount of fluorophore labels were released from the designed fluorescence DNA probe. During the homogeneous reaction process, the Exo III-assisted dual recycling significantly amplified the fluorescence signal output. Moreover, the excessive probes were easily adsorbed and separated by the Fe3O4@PDA nanocomposite, which decreased the background signal and increased the signal-to-noise ratio. These strategies result in the excellent analytical performance of the method, including a very low detection limit of 0.023 pg mL−1 and a very wide linear range of six orders of magnitude. In addition, this method has convenient operation, excellent selectivity, repeatability and satisfactory reliability, and does not involve the design and utilization of complicated DNA sequences. Thus, it exhibits a promising prospect for practical applications. [ABSTRACT FROM AUTHOR]

A cucurbit[6]uril-based (CB[6]) luminescent supramolecular assembly [CdL4]2−·CB[6] (1) has been successfully synthesized using anthracene carboxylic acid (HL) as a structure-directing agent. It has high water stability, easy regeneration ability and rapid response time. Investigation reveals that among the 12 species of antibiotics under investigation, 1 displayed high selectivity toward nitrofurazone (NFZ) and nitrofurantoin (NFT) through luminescence quenching, and the detection is not disturbed by the presence of other species. The limit of detection (LOD) for NFZ and NFT were calculated to be 90 and 49 ppb, respectively, indicating the ultra-sensitivity. Further studies reveal that 1 can be successfully applied for the detection of NFZ in simulated wastewater and urine with satisfactory results. More exhilaratingly, test strips based on 1 were successfully prepared, which can be used for naked-eye sensing of NFZ and NFT in water with emission color changes from bright blue to dark. These interesting results indicate that 1 can serve as a promising luminescent sensor in various potential applications. [ABSTRACT FROM AUTHOR]

Serious healthcare concerns have been raised on the issue of antibiotic residues after overuse, especially by accumulation in the human body through food webs. Here, we report a methodological development for sensitive detection of antibiotics with aptamer conformation cooperated enzyme-assisted SERS (ACCESS) technology. We design and integrate a set of nucleic acid oligos, realizing specific recognition of chloramphenicol (CAP) and efficient exonuclease III-assisted DNA amplification. It features a “signal-on” analysis of CAP with the limit of detection (15 fM), the lowest concentration detectable in the literature. Our method exhibits a high selectivity on the target analyte, free of interference of other potential antibiotic contaminants. The ACCESS assay promises an ultrasensitive and specific detection tool for trace amounts of antibiotic residues in samples of our daily life. [ABSTRACT FROM AUTHOR]

DNA walkers, one of the artificial molecular machines which are constructed via smart synthetic DNA, have attracted rapidly growing attention from researchers in the biosensing field. In this work, we design an Exonuclease III (Exo III)-aided target-aptamer binding recycling (ETBR) activated bipedal DNA machine for highly sensitive electrochemical detection of antibiotics. To the best of our knowledge, this is the first time that a bipedal DNA machine has been applied in electrochemical sensing for antibiotics. On the one hand, the bipedal DNA walker exceeds the conventional single swing arm DNA walker in terms of walking efficiency and stability. On the other hand, the ETBR strategy, along with efficient strand displacement amplification via stepwise movement of a bipedal DNA walker significantly promotes the signal amplification efficiency. Under optimal conditions, this bipedal DNA machine possesses a detection limit of 7.1 fM within a linear detection range from 10 fM to 100 pM. Moreover, this electrochemical biosensor is expected to detect a wide variety of analytes using the corresponding target recognition probes. Thus, our proposed strategy offers a highly efficient, stable and practical platform for small molecule analysis. [ABSTRACT FROM AUTHOR]