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A CQDs-doped europium-DPA framework for fluorescence and colorimetric dual-mode sensing of amoxicillin and ciprofloxacin

Yi Jintao,Fu Nani,Zhong Wenhui,Liu Xia,Zhou Anqi,Li Xun

Amoxicillin (AMO), a penicillin antibiotic, and ciprofloxacin (CIP), a quinolone antibiotic, are widely used to combat bacterial infections and are frequently co-administered to enhance therapeutic efficacy. However, improper use of AMO and CIP may lead to antibiotic residues in the environment, posing serious threats to human health. The visual detection of AMO and CIP remains significant challenges. Herein, the Eu-DPA@CQDs was used for the dual-mode detection of AMO and CIP, which was synthesized by CQDs doped in europium-DPA metal-organic framework. In the colorimetric mode, the catalase-mimicking Eu-DPA@CQDs oxidized TMB to blue oxTMB. Upon addition of AMO, the oxTMB was reduced, causing color fading. Subsequent introduction of CIP restored nanozyme activity, regenerating the blue signal and enabling dual-analyte antibiotic detection. In the fluorescence mode, the Eu-DPA@CQDs probe exhibited dual emission at 440 nm and 613 nm. Upon AMO addition, the fluorescence at both wavelengths was quenched, accompanied by a color change from red to purple. In the presence of CIP, the emission at 440 nm increased and redshifted to 490 nm, while the signal at 613 nm was quenched, resulting in a multicolor transition from red to cyan. The Eu-DPA@CQDs sensor enabled rapid and dual-mode detection of AMO and CIP. The colorimetric method exhibited wide linear ranges of 0.005–25 μM for AMO and 0.007–4.25 μM for CIP, with detection limits of 1.67 nM and 3.75 nM, respectively. A visible color transition from dark blue to colorless was observed with increasing AMO concentration, while the addition of CIP reversed the signal back to dark blue. Similarly, the fluorescence detection achieved wide linear ranges from 0.005 to 30 μM for AMO and 0.005 to 15 μM for CIP, with detection limits as low as 4.74 nM and 3.11 nM, respectively, also within only 1 min. As the concentration of AMO increased, the color shifted from red to purple. In contrast, increasing CIP concentration induced a color transition from red to cyan. These color transitions were both clearly visible to the naked eye. The sensor demonstrated excellent selectivity and anti-interference capability, providing a reliable platform for accurate, sensitive, and quantitative determination of both antibiotics in real samples. Graphical abstract

Bifunctional red-emitting copper-doped carbon dots as fluorescent probes and peroxidase nanozymes for dual-mode ampicillin detection with theoretical insights

Shan Huang,Pingping Mu,Guixin Li,Yutong Zhao,Silin Li,Yi Fang,Fuxiang Wei,Qi Xiao

Cu, B, N, S co-doped CDs with Cu–N₂O₂ sites were hydrothermally synthesized. • Cu-CDs function as both a red-emitting fluorophore and a peroxidase nanozyme in a single nanostructure. • The ·O 2 − generated by the nanozyme oxidizes TMB, quenching fluorescence and producing color. • AMP strongly adsorbs to the Cu site, scavenges ·O 2 − , and restores the fluorescence. • The dual-mode platform detects AMP at LODs of 0.78 μM (fluorescence) and 0.62 μM (colorimetry). Integrating optical signaling and enzymatic catalysis into a single nanostructure offers a promising route for biosensing. This work presents bifunctional copper-doped carbon dots (Cu-CDs) that serve simultaneously as red-emitting fluorescent probes (emission at 602 nm, quantum yield 15.84%) and as peroxidase-mimicking nanozymes for dual-mode detection of ampicillin (AMP). Hydrothermal treatment of 2,5-diaminotoluene sulfate and 3-aminophenylboronic acid with Cu 2+ produces spherical Cu-CDs (2.68 ± 0.15 nm) featuring well-defined Cu–N 2 O 2 coordination sites. Electron paramagnetic resonance spectroscopy and radical scavenging experiments confirm that the Cu–N 2 O 2 sites catalyze H 2 O 2 to generate of superoxide radicals (·O 2 − ), which oxidize 3,3′,5,5′-tetramethylbenzidine (TMB) to coloured oxTMB. The oxTMB absorbs strongly at 674 nm, spectrally overlapping with the Cu-CDs emission and quenching it through an inner filter effect-dominated static quenching mechanism. Density functional theory calculations reveal a catalytic cycle mediated by a Cu 2+ /Cu + redox couple and further demonstrate that AMP adsorbs much more strongly (−2.425 eV) than TMB (−1.578 eV) on the Cu–N 2 O 2 site. Consequently, AMP suppresses oxTMB formation not by homogeneous radical scavenging but through surface-adsorption-driven competitive inhibition, leading to fluorescence recovery and a decrease in absorbance at 674 nm. This dual-readout platform quantifies AMP over 1–150 μM (fluorometric, LOD 0.78 μM) and 1–80 μM (colorimetric, LOD 0.62 μM). It exhibits excellent selectivity against common ions, amino acids and various antibiotics, including structurally similar β-lactams (penicillin G, penicillin V, amoxicillin, cephalexin). Validation with real water samples and pharmaceutical preparations (ampicillin capsules and injections) gives recoveries of 90.40–109.20%. The integrated probe provides a robust self-validating strategy for environmental monitoring and pharmaceutical quality control. Download: Download high-res image (172KB) Download: Download full-size image

Robust ZIF-8 and its derivative composite membrane for antibiotic desalination with high performance

Chengcheng Wang,Hao Sun,Naixin Wang,Quan-Fu An

Zeolitic imidazolate framework (ZIF) membranes have great potential applications in nanofiltration. However, preparing continuous and intact ZIF membranes on the surface of a substrate remains challenging. In this study, we assembled ZIF-8 nanoparticles in situ in the pores of a porous alumina substrate via a freezing-assisted counter-diffusion method. Although a continuous ZIF-8 membrane was not formed on the surface of the substrate, the obtained nano-confined composite membrane was dense enough to separate antibiotics and salt. The rejection rate of tetracycline was above 99 %, while that of sodium chloride was below 20 %, demonstrating good antibiotic desalination performance. The permeance of the ZIF-8 membrane reached 23.5 LMH/bar. Due to the nano-confined structure, the obtained ZIF-8 composite membrane was robust. Besides, polishing the surface layer did not reduce the separation performance. Moreover, sulfurizing the ZIF-8 membrane improved its stability in water. It also improved the permeance to 31.3 LMH/bar, which remained stable for 100 h. Therefore, the obtained robust ZIF-8 membrane and its derivative composite membrane fabricated via freezing-assisted counter-diffusion have great potential in antibiotic desalination.

Rapid Determination of Cephalexin in Animal-Derived Food by an Indirect Competitive Enzyme-Linked Immunosorbent Assay

Shuangmin Wu,Wei Shen,Yushuang Chen,Yongli Zhu,Ren Hou,Menghong Dai,Dapeng Peng

A flow-through UV/electro-chlorine process for cost-effective and multifunctional purification of marine aquaculture wastewater

Zhicheng Lang,Xiangru Song,Ge Song,Lujie Han,Qizhan Zhang,Minghua Zhou

This study validated the feasibility of the simultaneous removal of antibiotics such as sulfamethazine and other pollutants including ammonia nitrogen, nitrate nitrogen and phosphorus, as well as disinfection in marine aquaculture wastewater by using a flow-through ultraviolet/electro-chlorine (EO+UV) process, comparing the removal performance and energy consumption with that by separate EO and UV process. Due to the co-action of multiple radicals and free chlorine, the removal of sulfamethazine and ammonia nitrogen by using EO+UV process was much higher than that by using EO and UV. This process could achieve complete inactivation of bacteria and removal of sulfamethazine under optimal conditions of 10 mA (1.4 mA/cm 2 ), flow rate 15 mL/min and pH 8.0. It also exhibited an effective removal of other antibiotics (norfloxacin, chloramphenicol and cephalexin). During treatment, 5.0–87.0 mg/L free chlorine was generated by EO process at current of 10–50 mA (1.4–7.1 mA/cm 2 ), and it was further converted into a variety of radicals under UV irradiation such as hydroxyl (4.95–9.45 μmol/L) and chlorine radical, which greatly improved the performance and reduced the energy consumption to only 19.0 kWh/kg, far lower than other processes. This flow-through EO+UV process had great practical application prospects for the comprehensive removal of multiple pollutants especially antibiotics and sterilization from marine aquaculture wastewater.

Relying on the non-radical degradation of oxytetracycline by peroxymonosulfate activated with a magnetic Cu/Fe composite: performance and mechanism

Jiabao Sun,Qiang Li,Dajie Zhang,Dongsheng Xia

Oxytetracycline (OTC) is a typical antibiotic that poses a serious threat to the environment. However, traditional treatment methods suffer from low treatment efficiencies and potential secondary contamination. Therefore, there is a need to develop efficient, convenient, and environmentally friendly removal technology. In this paper, magnetic nano-Cu/Fe composites were successfully synthesized and used as the activator of peroxymonosulfate (PMS) to degrade OTC. The obtained catalysts with different ratios showed excellent degradation effects, especially the Cu/Fe-1 catalysts. The highest removal efficiency of OTC (93%) was achieved with 0.2 g L−1 PMS and 0.1 g L−1 catalyst in 60 min. The impacts of the catalyst and PMS dosages, initial temperature and pH, coexisting anions, microplastics, and real-life water samples were investigated. To explore the mechanism for OTC degradation, radical scavenging and electron spin resonance (EPR) experiments were carried out, and non-radical 1O2 was identified to be the main radical. TEM and XRD results show the presence of CuFe2O4 composites in Cu/Fe-1, which can promote the production of 1O2 and thus improve the OTC degradation efficiency. This work provides a new efficient, stable, low-cost, and environmentally friendly approach for the degradation of oxytetracycline.

Facile one-pot synthesis of tannic acid-stabilized fluorescent copper nanoclusters and its application as sensing probes for chlortetracycline based on inner filter effect

Yu-yu Guo,Yu-rui Hu,Shao-ke Chen,Ming-zhu Guo,Yi-ting Zhang,Xin-rui Han,Shen Zhang

In this paper, a simple and one-pot synthetic strategy was established to prepare copper nanoclusters by using tannic acid as the template and ascorbic acid as the reducing agent. The tannic acid-capped copper nanoclusters (Cu NCs@TA) displayed excitation and emission peaks around 365 and 435 nm with fluorescence quantum yield of 9.8%. Based on the inner filter effect and static quenching mechanisms, the Cu NCs@TA was used to selectively and sensitively determine the chlortetracycline . Under the optimal detection conditions, the excellent linear range of 0.5–200 μM was obtained and the limit of detection (LOD) was gained as 0.084 μM. The satisfactory recoveries of 94.4~103.1% in real bovine serum samples indicated that this platform could be employed in practical test of chlortetracycline.

Mixed matrix nanocomposite imprinted membranes with multilevel hierarchical structure for high-efficiency selective recognition and separation: A bioinspired dual-imprinted strategy

Yilin Wu,Haian Xia,Qingyan Guo,Faguang Ma,Kaicheng Zhang,Jianming Pan

Mixed-matrix membranes with metal-organic frameworks (MOFs)-based dual-imprinted structure (MMM-MDIs) were prepared by choosing tetracycline (TC) as the template molecule. Polydopamine (PDA)-based TC-imprinted UiO-66 particles (PDA-TC-UiO-66) were constructed by developing a self-polymerization imprinting technique of dopamine, in which the dopamine molecule could be regarded as functional monomer and cross-linking agent in the same time. After the phase conversion membrane production, the sol-gel-based TC-imprinted structure could be then synthesized on the membrane surface. Importantly, due to the preparation of the dual-TC-imprinted structure in MMM-MDIs, high adsorption capacity (48.62 mg/g) and fast adsorption equilibrium rate (within 60 min) had been successfully achieved. Meanwhile, excellent permselectivity rates ( β ) of MMM-MDIs toward TC were also obtained as 6.33, 5.93 and 6.73, which demonstrated the successful synthesis of high-affinity and high-density TC-imprinted sites. Overall, based the practical selective separation and scalability analysis, we believed that the as-prepared MMM-MDIs with high-intensitive recognizability and permeability of template molecule would provide a possibility for breaking the permeability-selectivity trade-off of molecularly imprinted membrane materials.

Enhanced ozonation of pollutants by MgO nanoclusters/sewage sludge-derived hierarchical porous carbon: experimental and theoretical study

Siyang Li,Shujuan Zhan,Jingxiang Sun,Lingai Yao,Jinzhu Zhu,Jinxi Feng,Ya Xiong,Shuanghong Tian

Highly reactive nanoclusters of metal oxides are extremely difficult to synthesize due to their thermodynamic instability. For the first time, MgO nanoclusters supported on sewage sludge-derived hierarchical porous carbon (MgO nanoclusters/SC) were successfully prepared by grafting 1.31 ± 0.03 mmol g−1 acidic groups on the SC, then dynamically controlling the chemisorption of Mg2+ on the modified SC within 20 s, and finally transforming the fixed Mg2+ into MgO nanoclusters with a size of less than 2.4 nm via thermal treatment. Moreover, the cluster size could be facilely tailored by controlling the dynamic adsorption time and initial aqueous Mg2+ concentration. The resulting five MgO nanoclusters/SC-20 s samples with 0.43–1.12% (mass percentage) Mg have a turnover frequency of 0.038 towards the catalytic ozonation of 4-chlorophenol, much higher than those of the bigger nanoclusters and nanocrystals (i.e. MgO/SC-20 s with 1.43% Mg, MgO/SC-3 min with 0.85–2.0% Mg). The pseudo-first-order reaction constant of MgO nanoclusters/SC with 1.12% Mg is 0.0126 min−1, 6.0 and 4.1 times that of SC and bulky MgO/SC, respectively. The presence of MgO nanoclusters/SC also enhanced the removal of cephalexin, florfenicol and sulfamethoxazole by 54.3%, 45.5%, and 57.4%, respectively. The high activity can be ascribed to the rich and highly under-coordinated Mg in the smaller MgO nanoclusters and the unblocked hierarchical pores of the SC support. Finally, DFT calculations revealed at the atomic level that the under-coordinated Mg in MgO nanoclusters could directly or indirectly activate ozone through the protonated hydroxyl or just hydroxyl bonded to the under-coordinated Mg. Except for (MgO)2, the smaller the nanocluster, the higher the activity. This work shed a light on the design and preparation of highly reactive nanoclusters of metal oxide catalysts for catalytic ozonation of refractory organic pollutants.

Difunctional covalent organic framework hybrid material for synergistic adsorption and selective removal of fluoroquinolone antibiotics

Wei Jiang,Wei-Rong Cui,Ru-Ping Liang,Jian-Ding Qiu

ABSTRACT Due to the low efficiency of traditional sewage treatment methods, the effective removal of zwitterionic fluoroquinolone (FQs) antibiotics is of vital significant for environment protection. In this work, a SO 3 H-anchored covalent organic framework (TpPa-SO 3 H) was deliberately designed by linking phenolic trialdehyde with triamine through Schiff reaction, then low-content Tb 3+ ions were loaded onto covalent organic framework according to wet-chemistry immersion dispersion method which benefitting for efficient FQs antibiotics uptaking. Tb@TpPa-SO 3 H functionalized with regularly distributed sulfonic acid groups and terbium ions which could provide difunctional binding sites. Tb 3+ sites could capture carboxylic acid group of FQs molecules according to the complexes coordination effect and sulfonic acid sites play a significant role in the adsorption of FQs molecules through electrostatic interaction with amine group. Tb@TpPa-SO 3 H with dual complementary function sites exhibited ultra-fast adsorption kinetics (< 2 min, average over 99% removing rate) and high adsorption capacities of 989, 956, and 998 mg g −1 for Norfloxacin (NOR), ciprofloxacin (CIP), enrofloxacin (ENR), respectively. Furthermore, Tb@TpPa-SO 3 H showed excellent selectivity for the adsorption of FQs in tanglesome system. This work not only explored synergistic adsorption in ion-functionalized 2D covalent organic framework with dual binding sites, but also delineated a promising strategy for the elimination of organic pollutants in environmental remediation.

Green synthesis of weissella-derived fluorescence carbon dots for microbial staining, cell imaging and dual sensing of vitamin B12 and hexavalent chromium

Xiuling Ji,Suping Wang,Yiyong Luo,Xiaotian Yuan,Yunlin Wei,Qi Zhang,Kunhao Qin,Yujiao Tu

Due to small size, strong fluorescence and low cytotoxicity, fluorescent carbon dots (CDs) attract people's attention. The CDs- Ws derived from Weissella sp. Kl-3 with bright blue photoluminescent were obtained via hydrothermal method . The CDs- Ws could selectively label dead bacterial and yeast cells, and show the potential for the differentiation of live/dead microbe. It showed that the prepared CDs- Ws had multicolor fluorescence emission properties, excellent biocompatibility and low biotoxicity with cell and in vivo imaging. In addition, CDs- Ws sensitized by ampicillin sodium was employed as fluorescence nanosensor (CDs- Ws -Amp Na) to detect Cr(VI) and VB 12 based on inner filter effet mechanism. The linear correction was obtained for VB 12 detection in 0–25 μM with 51.50 nM detection limit, and the linear range was 0–50 μM with 106.57 nM detection limits for Cr(VI) by CDs- Ws -Amp Na. The fluorescent nanosensor was used for detection of Cr(VI) in water and VB 12 in serum and milk. It shows excellent potential in bioimaging , Cr(VI) and VB 12 detection.

Hydrothermal synthesis of Auricularia auricula derived nitrogen, phosphorus-doped carbon dots and application in Ag(I) and 4-nitrophenol detection and bioimaging

Yujiao Tu,Suping Wang,Xiaotian Yuan,Pengfei Song,Yunlin Wei,Kunhao Qin,Qi Zhang,Xiuling Ji

Novel fluorescent nitrogen and phosphorus-doped carbon dots (Aa N,P-CDs) derived from Auricularia auricula were successfully prepared via a simple hydrothermal method. The Aa N,P-CDs showed high selectivity and sensitivity in detection of 4-nitrophenol (4-NP) and Ag(I) and good linear ranges of 4-NP (0–37.5 μM, R2 = 0.9967) and Ag(I) (0–25 μM, R2 = 0.9934). The low detection limits were 198 nM and 74.35 nM, respectively. This showed that static quenching dominated in Ag(I) quenching of the Aa N,P-CD fluorescence, while that of 4-NP was the inner filter effect. The Aa N,P-CDs were successfully used to detect 4-NP and Ag(I) in real water and soil samples. Cell imaging indicated that Aa N,P-CDs showed low biotoxicity and good biocompatibility, which provided a new insight into bioimaging application and environmental pollutant detection.