Detection of Ciprofloxacin in Urine through Sensitized Lanthanide Luminescence

Fluorescent responsive membrane based on terbium coordination polymer and carbon dots with AIE effect for rapid and visual detection of fluoroquinolone

In this study, based on aggregation-induced emission (AIE) effect and antenna effect, a novel portable fluorescent responsive membrane was constructed with red carbon dots (R-CDs) as reference signal and terbium coordination polymer (Tb-AMP CPs) as response signal for visual, instrument-free, and sensitive detection of fluoroquinolones (FQs). Specifically, the fluorescent responsive membrane (R-T membrane) was prepared by physically depositing R-CDs with AIE property and Tb-AMP CPs on the surface of polyvinylidene fluoride filter membranes at ambient temperature. In the presence of FQs, Tb3+ in the Tb-AMP CPs of the prepared membrane coordinated with the β-diketone structure of FQs, which turned on the yellow-green fluorescence through the "antenna effect". As the concentration of FQs increased, the R-T membrane achieved a fluorescent color transition from bright pink to yellow-green. Its visual detection sensitivity for three FQs, including ciprofloxacin, difloxacin, and enrofloxacin, was 0.01 μM, and the detection limits were 7.4 nM, 7.8 nM, and 9.2 nM, respectively, by analyzing the color parameter green. In the residue analysis of FQs in real samples, the constructed membrane also exhibited remarkable anti-interference and reliability, which is of great significance for ensuring the safety of animal-derived food.

Glutamic acid-capped iron oxide quantum dots as fluorescent nanoprobe for tetracycline in urine

The fabrication of iron oxide quantum dots (IO-QDs) modified with glutamic acid (Glu) under controllable conditions is reported. The IO-QDs have been characterized by transmission electron microscopy, spectrofluorometry, powder X-ray diffraction, vibrating sample magnetometry, UV-Vis spectroscopy, X-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy. The IO-QDs exhibited good stability towards irradiation, temperature elevations, and ionic strength, and the quantum yield (QY) of IO-QDs was calculated to be 11.91 ± 0.09%. The IO-QDs were furtherly measured at an excitation wavelength of 330 nm with emission maxima at 402 nm, which were employed to detect tetracycline (TCy) antibiotics, including tetracycline (TCy), chlortetracycline (CTCy), demeclocycline (DmCy), and oxytetracycline (OTCy) in biological samples. The results indicated that TCy, CTCy, DmCy, and OTCy in urine samples show a dynamic working range between 0.01 and 80.0 μM; 0.01 and 1.0 μM; 0.01 and 10 μM; and 0.04 and 1.0 μM, respectively, with detection limits of 7.69 nM, 120.23 nM, 18.20 nM, and 67.74 nM, respectively. The detection was not interfered with by the auto-fluorescence from the matrices. In addition, the obtained recovery in real urine samples suggested that the developed method could be used in practical applications. Therefore, the current study has prospect to develop an easy, fast, eco-friendly, and efficient new sensing method for detecting tetracycline antibiotics in biological samples.

Citrate Functionalized Zirconium-Based Metal Organic Framework for the Fluorescent Detection of Ciprofloxacin in Aqueous Media

Ciprofloxacin (CIP) is a commonly used antibiotic for the treatment of infectious diseases in humans and as a prophylactic agent in the livestock industry, leading to the environmental discharge of significant amounts of CIP. CIP is stable in aquatic systems leading to its pseudo-persistence. Constant exposure to these antibiotics results in the generation of antibiotic-resistant pathogens and potential toxicity/hypersensitivity in humans. Therefore, it is necessary to develop a convenient, rapid, and cost-effective method for the monitoring of ciprofloxacin in environmental samples. Rhodamine-based fluorescent receptors have the limitation of aqueous solubility. Therefore, in order to overcome this drawback, we designed a novel fluorescent receptor based on a zirconium-based metal organic framework (MOF-808). The precursor, MOF-808, was synthesized and functionalized by using sodium citrate to obtain a receptor called C-MOF-808. The C-MOF-808 was structurally characterized by XRD and spectroscopic analyses. Thus, this synthesized receptor can be used for the fluorescent detection of CIP in aqueous media with a detection limit of 9.4 µM. The detection phenomena of the receptor were studied by absorption as well as fluorescent spectra. The binding behavior of CIP with the receptor was studied by FT-IR and ¹H-NMR analyses, and a binding mechanism is proposed.

Novel sensing probe using Terbium-sensitized luminescence and 8-hydroxyquinoline for determination of prucalopride succinate: green assessment with Complex-GAPI and analytical Eco-Scale

A highly sensitive spectrofluorimetric method is developed for the determination of prucalopride succinate (PRU). The method depends on lanthanide-sensitized luminescence due to complex formation between the drug and terbium chloride (Tb⁺³) which is enhanced by the addition of 8 hydroxyquinoline (8HQ) and phosphate buffer (0.02 M, pH 3.2). The calibration curve was constructed over the linear range 10–300 ng/mL after excitation at 226 nm and measuring the emission of the ternary complex at 544 nm. The method was validated according to ICH Q2 (R1) guidelines and showed a good recovery ± RSD of 100.41% ± 1.26, the limits of detection and quantitation were found to be 2.81 and 8.53 ng/mL, respectively. The proposed method was successfully applied for the determination of the drug marketed tablet dosage form and the results were in good agreement with the reference method. Also, the method greenness was evaluated according to Complex-GAPI and analytical Eco-Scale.

Colloidal biochar for enhanced adsorption of antibiotic ciprofloxacin in aqueous and synthetic hydrolyzed human urine matrices

Objectives of the present research were to examine the capacity of disc-milled high lignin biochar colloids (CBC) for the removal of ciprofloxacin (CPX) from aqueous solution and synthetic hydrolyzed human urine. In this study, adsorption of CPX was tested against the initial pH (3-10), ionic strength (0.001-0.1 M NaNO₃), resident time (up to 8 h), initial CPX concentration (5-100 mg/L) and temperature (25, 35, and 45 °C). The surface morphology was examined using Brunauer-Emmett-Teller (BET) specific surface area. The CBC was observed to be < 300 nm whereas the BET surface area was 284 m²/g. Best CPX adsorption demonstrated at pH 5-6 and however, indicated ionic strength dependency. Experimental kinetics data in aqueous media were well-fitted to the pseudo-second-order (r² of 0.98), while the Hill and Langmuir isotherm models best described the isotherm data (r² of 0.95 and 0.94, respectively) confirming chemisorption followed by physisorption interactions. The thermodynamics results indicate that CPX adsorption onto CBC is spontaneous (-ΔG), endothermic (+ΔH) and has increased randomness (+ΔS) in the aqueous system. The kinetic experimental data in synthetic urine matrix was fitted with Elovich (r² = 0.99) and fractional power (r² = 0.96) models whereas Hills (r² = 0.99) and Langmuir (r² = 0.97) models were the most fitted with isotherm data suggesting the adsorption of CPX on the CBC by chemisorption mechanisms. In conclusion, CBC demonstrated effective removal of CPX indicating its potential to be used in wastewater treatment.

Ratiometric fluorescence detection of ciprofloxacin using the terbium-based coordination polymers

Herein, a facile self-assembly through adenosine monophosphate (AMP) and luminol with Tb³⁺ was employed to construct a dual-ligand coordinated AMP-Tb-luminol coordination polymers (CPs), which emitted the typical fluorescence of luminol. Based on the sensitization effect of ciprofloxacin (CIP) on the luminescence of Tb³⁺, a ratiometric sensor was fabricated using the fluorescence of luminol as an inert reference. The fluorescent intensity ratios of Tb³⁺ to that of luminol enhanced linearly with the CIP concentration in the range from 5 nM to 2.5 μM with a lower limit of detection of 2 nM. In addition, the proposed ratiometric fluorescent sensor exhibited high selectivity for CIP, which could also be used to detect CIP in human blood serum (HBS) with satisfactory results. To our knowledge, this is the first demonstration of using dual-ligand coordination lanthanide (Ln)-based CPs for ratio-metric CIP assay, and this straightforward strategy may open up a new platform for designing the ratio-metric sensors based on the Ln CPs.

Ratiometric rapid distinction of two structurally similar fluoroquinolone antibiotics by a Tb/Eu hydrogel

Rapid distinction of structurally similar fluoroquinolone antibiotics norfloxacin and ofloxacin, and their quantification in a mixture, were achieved using a supramolecular Tb/Eu gel cocktail.

Moxifloxacin detection based on fluorescence resonance energy transfer from carbon quantum dots to moxifloxacin using a ratiometric fluorescence probe

With an increase in the MOX concentration, the fluorescence intensity of CQDs decreases, whereas the fluorescence intensity of MOX increases gradually.

Silicon nanoparticles-based ratiometric fluorescence platform: Real-time visual sensing to ciprofloxacin and Cu2

In this work, a silicon nanoparticles (Si NPs)-based ratiometric fluorescence sensing platform was conveniently fabricated by simply mixing fluorescent Si NPs as co-ligands and reference signal with lanthanide metal ion Eu³⁺ as response signal. The introduction of ciprofloxacin (CIP) remarkably turned on the characteristic fluorescence of Eu³⁺ at 590 nm and 619 nm through the "antenna effect". At the same time, the blue emission of Si NPs at 445 nm kept comparatively stable. A good linear relationship between the ratio fluorescence intensity and CIP concentration in the range of 0.211-132.4 μM with a limit of detection (LOD) of 89 nM was obtained. In the presence of Cu²⁺, the fluorescence emission of Eu³⁺ was sharply turned off because of the stronger coordination ability of Cu²⁺ with CIP, which guaranteed the sequential detection of Cu²⁺. Meanwhile, the distinct fluorescent color change from bright blue to red, then back to blue, enabled naked-eye visual detection of CIP and Cu²⁺ in the solution phase and on paper-based test strip, and was successfully applied to determine the levels of CIP in complicated food samples with high sensitivity.

Construction of a high-nuclearity Nd(III) nanoring for the NIR luminescent detection of antibiotics

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.

Construction of Zn(II)/Cd(II)-Yb(III) Schiff Base Complexes for the NIR Luminescent Sensing of Fluoroquinolone Antibiotics

Two NIR luminescent Zn(II)/Cd(II)-Yb(III) complexes were obtained by the use of a Schiff base ligand with a binaphthyl backbone. Cd(II)-Yb(III) complex 2 has a triangular structure and exhibits interesting luminescent sensing activity to antibiotics, in particular to ciprofloxacin (CPFX) and norfloxacin (NFX) due to the inner filter effect. The limits of the detection of 2 to CPFX and NFX are 0.18 and 0.36 μM, respectively, and the fluorescence sensitivity is not changed with the existence of other antibiotics tested in this study.

Construction of a 18-Metal Neodymium(III) Nanoring with NIR Luminescent Sensing to Antibiotics

One 18-metal Nd(III) nanoring, [Nd₁₈(L¹)₈(HL²)₂(OAc)₂₀(MeOH)₈(EtOH)₆(H₂O)₄]·2(MeOH)·6(H₂O) (1), was constructed by the use of a hexadentate Schiff base ligand. For 1, the near-infrared (NIR) luminescence of Nd(III) was detected under the excitation of absorption band at 371 nm. The study of luminescent sensing properties exhibits that, even with the existence of other antibiotics, this Nd(III) nanoring displays high sensitivity and selectivity to nitrofuran antibiotics (NFAs). The luminescence quenching constants and limits of detection of 1 to NFAs are found to be 1.4 × 10⁴ to 3.5 × 10⁴ M^-1 and 0.9-2.2 μM, respectively.

One High-Nuclearity Cd(II)-Yb(III) Nanoring with Near-IR Luminescent Sensing to Antibiotics

One 12-metal Cd(II)-Yb(III) nanoring, [Cd₈Yb₄L₈(OAc)₈]·4OH (1), with a size of 1.2 × 2.8 × 2.8 nm was obtained from a designed flexible salen-type ligand that has eight coordination sites (O and N atoms). The near-IR emission of Yb(III) at 983 nm was detected upon the excitation of ligand-central absorption at 386 nm. This Cd(II)-Yb(III) nanoring exhibits high sensitivity to nitrofuran antibiotics (NFAs) even in the presence of other antibiotics. The quenching constants and limits of detection of NFAs are 2.5 × 10⁴-4.5 × 10⁴ M^-1 and 1.5-2.8 μM, respectively.

Photophysical properties and energy transfer mechanism of a praseodymium compound with a two-dimensional layer

A hydrothermal reaction results in the formation of a novel [Pr2(2,5-PA)2(2,5-HPA)2(H2O)4] n·2 nH2O complex (2,5-H2PA = 2,5-pyridinedicarboxylic acid). The complex is structurally characterized by single-crystal X-ray diffraction and crystallizes in the space group P21 of the monoclinic system with two formula units in one cell. This praseodymium complex is characterized by a two-dimensional layered structure. A solid-state photoluminescence experiment reveals that the praseodymium complex shows an emission in the red region. The complex has Commission Internationale de I’Éclairage chromaticity coordinates of 0.5495 and 0.4492. The photoluminescence emission bands could be assigned to the characteristic emission of the 4 f electron intrashell transition of the 3 P0 → 3 H5, 1 D2 → 3 H4, 3 P0 → 3 H6, 3 P0 → 3 F2, and 3 P1 → 3 F3 of the Pr3+ ions. The energy transfer mechanism is explained by the energy level diagrams of the praseodymium ions and the 2,5-H2PA ligand. A solid-state diffuse reflectance measurement shows that the complex possesses a wide optical band gap of 3.48 eV.

Quinolone Complexes with Lanthanide Ions: An Insight into their Analytical Applications and Biological Activity

Quinolones comprise a series of synthetic bactericidal agents with a broad spectrum of activity and good bioavailability. An important feature of these molecules is their capacity to bind metal ions in complexes with relevant biological and analytical applications. Interestingly, lanthanide ions possess extremely attractive properties that result from the behavior of the internal 4f electrons, behavior which is not lost upon ionization, nor after coordination. Subsequently, a more detailed discussion about metal complexes of quinolones with lanthanide ions in terms of chemical and biological properties is made. These complexes present a series of characteristics, such as narrow and highly structured emission bands; large gaps between absorption and emission wavelengths (Stokes shifts); and long excited-state lifetimes, which render them suitable for highly sensitive and selective analytical methods of quantitation. Moreover, quinolones have been widely prescribed in both human and animal treatments, which has led to an increase in their impact on the environment, and therefore to a growing interest in the development of new methods for their quantitative determination. Therefore, analytical applications for the quantitative determination of quinolones, lanthanide and miscellaneous ions and nucleic acids, along with other applications, are reviewed here.

A Micellar-Enhanced Spectrofluorimetric Method for the Determination of Ciprofloxacin in Pure Form, Pharmaceutical Preparations and Biological Samples

A simple, fast and interference free spectrofluorimetric method was developed for the quantification of ciprofloxacin in its pure form, pharmaceutical preparations and in human plasma. The method is based on the enhancement of the weak fluorescence signal of drugs by the addition of sodium dodecyl sulphate (SDS) surfactant micelles in citrate buffer at pH 5.5. Different experimental parameters like buffers, surfactant type and concentration were investigated. The fluorescence intensity of ciprofloxacin was measured at 446 nm (emission) and at 328 nm (excitation). A linear relationship between concentration of ciprofloxacin and fluorescence intensity was found in the range of 0.04 μg/mL–6.0 μg/mL with a correlation coefficient of 0.9946. The limit of detection (LOD) and limit of quantification (LOQ) were calculated and found to be 3.87 × 10−5 and 1.29 × 10−4 μg/mL respectively. The effect of common excipients and co-administered drugs were also investigated and the method was found free of interferences. The method was successfully applied for the determination of ciprofloxacin in pharmaceutical preparations and human plasma with percentage recoveries of 97.08 % to 99.32 % and 95.00 % to 101.25 % respectively.

Ratiometric fluorescence, solution-phase and filter-paper visualization detection of ciprofloxacin based on dual-emitting carbon dot/silicon dot hybrids

This study demonstrates the ratiometric fluorescence, solution-phase and filter-paper visual detection of ciprofloxacin based on dual-emitting carbon dot/silicon dot hybrids.