Ratiometric fluorescence detection of superoxide anion based on AuNPs‐BSA@Tb/GMP nanoscale coordination polymers

A novel ratiometric fluorescence nanosensor for superoxide anion (O₂^??) detection was designed with gold nanoparticles‐bovine serum albumin (AuNPs‐BSA)@terbium/guanosine monophosphate disodium (Tb/GMP) nanoscale coordination polymers (NCPs) (AuNPs‐BSA@Tb/GMP NCPs). The abundant hydroxyl and amino groups of AuNPs‐BSA acted as binding points for the self‐assembly of Tb³⁺ and GMP to form core‐shell AuNPs‐BSA@Tb/GMP NCP nanosensors. The obtained probe exhibited the characteristic fluorescence emission of both AuNPs‐BSA and Tb/GMP NCPs. The AuNPs‐BSA not only acted as a template to accelerate the growth of Tb/GMP NCPs, but also could be used as the reference fluorescence for the detection of O₂^??. The resulting AuNPs‐BSA@Tb/GMP NCP ratiometric fluorescence nanosensor for the detection of O₂^?? demonstrated high sensitivity and selectivity with a wide linear response range (14 nM–10 μM) and a low detection limit (4.7 nM).     

Terbium (III) coordination polymer–copper (II) compound as fluorescent probe for time‐resolved fluorescence ‘turn‐on’ detection of hydrogen sulfide

With recognition of the biological importance of hydrogen sulfide (H₂S), we present a simple and effective fluorescent probe for H₂S using a Tb³⁺ coordination polymer–Cu²⁺ compound (DPA/Tb/G–Cu²⁺). Dipicolinic acid (DPA) and guanosine (G) can coordinate with Tb³⁺ to form a macromolecular coordination polymer (DPA/Tb/G). DPA/Tb/G specifically binds to Cu²⁺ in the presence of coexisting cations, and obvious fluorescence quenching is observed. The quenched fluorescence can be exclusively recovered upon the addition of sulfide, which is measured in the mode of time‐resolved fluorescence. The fluorescence intensities of the DPA/Tb/G–Cu²⁺ compound enhance linearly with increasing sulfide concentrations from 1 to 30 μM. The detection limit for sulfide in aqueous solution is estimated to be 0.3 μM (at 3σ). The DPA/Tb/G–Cu²⁺ compound was successfully applied to sense H₂S in human serum samples and exhibited a satisfactory result. It displays some desirable properties, such as fast detection procedure, high selectivity and excellent sensitivity. This method is very promising to be utilized for practical detection of H₂S in biological and environmental samples.     

Hg2+‐selective ratiometric and colorimetric probe based on dansyl–rhodamine and its staining function in cell imaging

A new ratiometric probe composed of a dansyl–rhodamine dyad for the detection of Hg²⁺ via fluorescence resonance energy transfer was designed and synthesized. Rhodamine, dansyl chloride, and hydrazide were selected as the acceptor, donor, and reaction site, respectively. It displayed high selectivity and sensitivity to Hg²⁺ with obvious colour change and fluorescence change due to Hg²⁺‐assisted hydrolysis of rhodamine hydrazide. A good linear relationship ranging from 0 to 16 μM and 0–28 μM for the Hg²⁺ concentration was found based on absorbance and fluorescence assay, respectively. Detection limits of absorbance and fluorescence for Hg²⁺ were calculated to be 1.22 μM and 9.10 μM, respectively.     

An OFF–ON–OFF type fluorescent probe based on a naphthalene derivative for Al3+ and F− ions and its biological application

A novel fluorescent probe‐based naphthalene Schiff, 1‐(C2‐glucosyl‐ylimino‐methyl)‐naphthalene‐2‐ol (L) was synthesized by coupling d ‐glucosamine hydrochloride with 2‐hydroxy‐1‐naphthaldehyde. It exhibited excellent selectivity and highly sensitivity for Al³⁺ in ethanol with a strong fluorescence response, while other common metal ions such as Pb²⁺, Mg²⁺, Cu²⁺, Co²⁺, Ni²⁺, Cd²⁺, Fe²⁺, Mn²⁺, Hg²⁺, Li⁺, Na⁺, K⁺, Fe³⁺, Cr³⁺, Zn²⁺, Ag⁺, Ba²⁺ and Ca²⁺ did not cause the same fluorescence response. The probe selectively bound Al³⁺ with a binding constant (K_a) of 5.748 × 10³ M^?1 and a lowest detection limit (LOD) of 4.08 nM. Moreover, the study found that the fluorescence of the L ? Al³⁺ complex could be quenched after addition of F^? in the same medium, while other anions, including Cl^?, Br^?, I^?, NO₂^?, NO₃^?, ClO₄^?, CO₃^2?, HCO₃^?, SO₄^2?, HSO₄^?, CH₃COO^?, PO₄^3?, HPO₄^2?, S^2? and S₂O₃^2? had nearly no influence on probe behaviour. Binding of the [L ? Al³⁺] complex to a F^? anion was established by different fluorescence titration studies, with a detection limit of 3.2 nM in ethanol. The fluorescent probe was also successfully applied in the imaging detection of Al³⁺ and F^? in living cells.     

A ratiometric fluorescence sensor based on carbon quantum dots realized the quantitative and visual detection of Hg2+

In this paper, based on the fluorescence of carbon quantum dots (CQDs) quenched by mercury ions (Hg²⁺) and the nonresponse of Hg²⁺ to rhodamine B fluorescence, a dual emission ratio fluorescence sensor was constructed to realize the quantitative detection of Hg²⁺. Under excitation at 365 nm, the fluorescence spectrum showed double emission peaks at 437 nm and 590 nm, corresponding to the fluorescence emissions of CQDs and rhodamine B, respectively. This method quantitatively detected Hg²⁺ based on the linear relationship between the ratio of the intensities of the two emission peaks F₄₃₇/F₅₉₀ and the concentration of Hg²⁺. The detection range was 10–70 nM, and the limit of detection (S/N = 3) was 3.3 nM. In addition, this method could also realize the qualitative and semiquantitative detection of Hg²⁺ according to the fluorescence colour change of the probe under ultraviolet light. After various evaluations, the method could be successfully applied to the quantitative and visual detection of Hg²⁺ in tap water, and demonstrated excellent selectivity, anti-interference performance, and repeatability of the method.     

Sensitive determination of protein based on the fluorescence enhancement effect of terbium (III)–epinephrine–protein–sodium dodecylsulfate system

It was found that the fluorescence of Tb³⁺–epinephrine (E) complex can be enhanced by both bovine serum albumin (BSA) and sodium dodecylsulfate (SDS), and stabilized by ascorbic acid (AA). It is considered that the fluorescence enhancement of the Tb³⁺–E–BSA–AA–SDS system originates not only from the hydrophobic microenvironment provided by BSA–SDS, but also from the energy transfer from BSA to Tb³⁺ in this system. Therefore, a new fluorescence method for the determination of protein concentrations as low as 1.3 × 10^?9 g mL^?1 BSA is established using Tb³⁺–epinephrine complex as probe. The method has been applied for the determination of BSA and human serum albumin in actual samples, and the results obtained are satisfactory. Compared with other fluorescence methods, this method is simpler and more sensitive for the determination of protein. The mechanism of the fluorescence enhancement of the system is studied in detail. Copyright © 2009 John Wiley & Sons, Ltd.     

Exploring the interactions of a Tb(III)–quercetin complex with serum albumins (HSA and BSA): spectroscopic and molecular docking studies

Serum albumins (human serum albumin (HSA) and bovine serum albumin (BSA), two main circulatory proteins), are globular and monomeric macromolecules in plasma that transport many drugs and compounds. In the present study, we investigated the interactions of the Tb(III)–quercetin (Tb–QUE) complex with HSA and BSA using common spectroscopic techniques and a molecular docking study. Fluorescence data revealed that the inherent fluorescence emission of HSA and BSA was markedly quenched by the Tb–QUE complex through a static quenching mechanism, confirming stable complex formation (a ground‐state association) between albumins and Tb–QUE. Binding and thermodynamic parameters were obtained from the fluorescence spectra and the related equations at different temperatures under biological conditions. The binding constants (K_b) were calculated to be 0.8547 × 10³ M^?1 for HSA and 0.1363 × 10³ M^?1 for BSA at 298 K. Also, the number of binding sites (n) of the HSA/BSA–Tb–QUE systems was obtained to be approximately 1. Thermodynamic data calculations along with molecular docking results indicated that electrostatic interactions have a main role in the binding process of the Tb–QUE complex with HSA/BSA. Furthermore, molecular docking outputs revealed that the Tb–QUE complex has high affinity to bind to subdomain IIA of HSA and BSA. Binding distances (r) between HSA–Tb–QUE and BSA–Tb–QUE systems were also calculated using the Forster (fluorescence resonance energy transfer) method. It is expected that this study will provide a pathway for designing new compounds with multiple beneficial effects on human health from the phenolic compounds family such as the Tb–QUE complex.     

Effects of Mn on oligonucleotide-gold nanoparticle hybrids for colorimetric sensing of Hg: Improving colorimetric sensitivity and accelerating color change

In this paper, we present a simple and rapid colorimetric assay – using the polythymine oligonucleotide T₃₃, citrate-capped gold nanoparticles (AuNPs), and phosphate-buffer saline (PBS) in the presence of Mn²⁺ – for the highly selective and sensitive detection of Hg²⁺ in an aqueous solution. Citrate-capped AuNPs adsorbed on randomly coiled T₃₃ were dispersed well in PBS because of strong electrostatic repulsion between DNA molecules. In the presence of Hg²⁺, the formation of Hg²⁺–T₃₃ complexes enabled the removal of T₃₃ molecules from the NP surface, resulting in salt-induced NP aggregation. However, the T₃₃-capped AuNPs (T₃₃-AuNPs) were dispersed in PBS solution after the addition of 1.0 μM Hg²⁺, indicating that T₃₃-AuNPs had poor colorimetric sensitivity toward Hg²⁺. We uncovered that the addition of Mn²⁺ to a solution containing 0.75 nM T₃₃-AuNPs and 0.2× PBS resulted in an acceleration of the analysis time (within 5 min) and a 100-fold sensitivity improvement for the detection of Hg²⁺. As a result, the present approach enables the analysis of Hg²⁺ with a minimum detectable concentration that corresponds to 10 nM. This is probably attributed to that Mn²⁺ binds strongly to the phosphate backbone of DNA, thereby accelerating Hg²⁺-induced aggregation of the T₃₃-AuNPs. Because Mn²⁺ can stabilize the folded structure of the Hg²⁺–T₃₃ complex, Hg²⁺ facilitates the removal of T₃₃ from the NP surface in the presence of Mn²⁺. This probe was successfully applied to the determination of Hg²⁺ in pond water.     

Detection of mercury(II) by DNA templated gold nanoclusters based on forming thymidine–Hg2+–thymidine duplexes

We have successfully synthesized gold nanoclusters (AuNCs) templated with DNA (5′‐CCCCCCCCCCCCTTTTTT‐3′), and subsequently employed the fluorescent DNA‐AuNCs as a novel probe for sensitive detections of mercury ions (Hg²⁺). Basically, the procedure is due to the formation of thymidine–Hg²⁺–thymidine duplexes between DNA‐AuNCs and Hg²⁺, thus leading to aggregations of DNA‐AuNCs described here occurring, and facilitating their fluorescence decrease. Significantly, this decrease of fluorescent signals permitted sensitive detection of Hg²⁺ in a linear range of 0.1–100 µmol L^?1, with a detection limit of 0.083 µmol L^?1 at a signal‐to‐noise ratio of 3. Additionally, the practicality of this probe for assaying Hg²⁺ in human urine and lake water samples was further validated, and showed various advantages including simplicity, selectivity, sensitivity and low cost, demonstrating its potential to broaden ways for assaying Hg²⁺ in real samples. Copyright © 2014 John Wiley & Sons, Ltd.     

Luminescent sensor for Cd2+, Hg2+ and Ag+ in water based on a sulphur‐containing receptor: quantitative binding–softness relationship

A water‐soluble, high‐output fluorescent sensor, based on a lumazine ligand with a thiophene substituent for Cd²⁺, Hg²⁺ and Ag⁺ metal ions, is reported. The sensor displays fluorescence enhancement upon Cd²⁺ binding (log  β = 2.79 ± 0.08) and fluorescence quenching by chelating with Ag⁺ and Hg²⁺ (log β = 4.31 ± 0.15 and 5.42 ± 0.1, respectively). The mechanism of quenching is static and occurs by formation of a ground‐state non‐fluorescent complex followed by rapid intersystem crossing. The value of the Stern–Volmer quenching rate constant (k_q) by Ag⁺ ions is close to 6.71 × 10¹² mol/L/s at 298 K. The thermodynamic parameters (ΔG, ΔH and ΔS) were also evaluated and indicated that the complexation process is spontaneous, exothermic and entropically favourable. The quantitative linear relationship between the softness values of Klopman (σ_K) or Ahrland (σ_A) and the experimental binding constants (β) being in the order of Hg²⁺ > Ag⁺ > Cd²⁺ suggests that soft–soft interactions are the key for the observed sensitivity and selectivity in the presence of other metal ions, such as: Pb²⁺, Ni²⁺, Mn²⁺, Cu²⁺, Co²⁺, Zn²⁺ and Mg²⁺ ions. Copyright © 2008 John Wiley & Sons, Ltd.     

A ratiometric fluorescence strategy based on copper nanoclusters/carbon dots for sensitive detection of doxorubicin

Sensitive detection of doxorubicin (DOX) is critical for clinical theranostics. A novel ratiometric fluorescence strategy based on the inner filter effect (IFE) has been established for the sensitive detection of DOX by designing a ratiometric fluorescence probe. In the presence of DOX, the fluorescence intensity of copper nanoclusters (CuNCs) at 485 nm decreases, and the fluorescence intensity of carbon dots at 560 nm increases. Therefore, DOX can be quantitatively detected by measuring the ratio of the fluorescence intensities at 560 and 485 nm (F₅₆₀/F₄₈₅). The F₅₆₀/F₄₈₅ ratio exhibits a linear correlation with the DOX concentration in the range from 1.0 × 10⁻⁸ M to 1.0 × 10⁻⁴ M with the detection limit of 3.7 nM. Furthermore, this method was also successfully applied to the analysis of DOX in human plasma samples, affording an effective platform for drug safety management.     

DNA‐based chemiluminescent nanoprobes for highly sensitive and selective detection of mercury(II) ion

A simple and sensitive DNA‐stablized gold nanoparticle (AuNP)‐based chemiluminescent (CL) probe for detecting mercury ion (Hg²⁺) in aqueous solution has been developed. The CL strategy relies upon the catalytic activity of unmodified AuNPs on the luminol–H₂O₂ CL reaction, and the interaction of unmodified AuNPs with DNA. The unmodified AuNPs can effectively differentiate unstructured and folded DNA. The DNA desorbs from AuNPs in the presence of Hg²⁺, leading to the increase in CL signal. By rationally varying the number of thymine in single‐strand oligonucleotides, the detection range could be tuned. Employing single‐strand oligonucleotides with 14 thymine in the detecting system, a sensitive linear range for Hg²⁺ ions from 5.0 × 10^–10 to 1.0 × 10^–7 mol/L and a detection limit of 2.1 × 10^–10 mol/L are obtained. Changing the number of thymine to 10 and 6, it leads to a narrow detection range but a high sensitivity. Besides, DNA‐based CL nanoprobes exhibit a remarkable selectivity for Hg²⁺ ions over a variety of competing metal ions. Copyright © 2012 John Wiley & Sons, Ltd.     

Synthesis,crystal structure and fluorescence properties of terbium complexes with phenoxyacetic acid and 2,4,6‐tris‐(2‐pyridyl)‐s–triazine

Two complexes of Tb³⁺, Gd³⁺/Tb³⁺ and one heteronuclear crystal Gd³⁺/Tb³⁺ with phenoxyacetic acid (HPOA) and 2,4,6‐tris‐(2‐pyridyl)‐s–triazine (TPTZ) have been synthesized. Elemental analysis, rare earth coordination titration, inductively coupled plasma atomic emission spectrometry (ICP‐AES) and thermogravimetric analysis‐differential scanning calorimetry (TG‐DSC) analysis show that the two complexes are Tb₂(POA)₆(TPTZ)₂·6H₂O and TbGd(POA)₆(TPTZ)₂·6H₂O, respectively. The crystal structure of TbGd(POA)₆(TPTZ)₂·2CH₃OH was determined using single‐crystal X‐ray diffraction. The monocrystal belongs to the triclinic system with the P‐1 space group. In particular, each metal ion is coordinately bonded to three nitrogen atoms of one TPTZ and seven oxygen atoms of three phenoxyacetic ions. Furthermore, there exist two coordinate forms between C₆H₅OCH₂COO^– and the metal ions in the crystal. One is a chelating bidentate, the other is chelating and bridge coordinating. Fluorescence determination shows that the two complexes possess strong fluorescence emissions. Furthermore, the fluorescence intensity of the Gd³⁺/Tb³⁺ complex is much stronger than that of the undoped complex, which may result from a decrease in the concentration quench of Tb³⁺ ions, and intramolecular energy transfer from the ligands coordinated with Gd³⁺ ions to Tb³⁺ ions. Copyright © 2015 John Wiley & Sons, Ltd.     

Unclonable fluorescence of MgO-ZrO2:Tb3+ nanocomposite for versatile applications in data security,dermatoglyphics

Latent fingerprints (LFPs) are one among the most important types of evidences at crime scenes because of the distinctiveness and tenacity of the friction ridges in fingerprints (FPs). Therefore, it is essential in forensic science to develop a reliable method to detect LFPs. Traditional detection methods still face a number of difficulties, such as limited sensitivity, low contrast, strong background, and complex processing stages. In this study, MgO-ZrO₂:Tb³⁺ (1–5 mol%) (MZ:Tb) nanocomposites (NCs) were prepared via a simple solution combustion (SC) method at low temperature. The photoluminescence (PL) investigation demonstrates that when excited at 379 nm, the produced NCs emits distinctive emission peaks of terbium ions (Tb³⁺). According to the photometric results, the NCs can be employed as warm light NCs and emit light in the green portion of the colour spectrum. The estimated optical band gap from diffuse reflectance spectra is found to be in the range 4.84–4.97 eV. Regardless of the type of surface being used, the optimized MgO-ZrO₂:Tb³⁺ (4 mol%) (MZ:4Tb) NCs has a strong ability to minimize background fluorescence interference. With high contrast LFP and I–V type of cheiloscopy, these NCs present a flexible fluorescent mark for the identification of levels 1–3 details in forensic investigation.     

Ratiometric fluorescent detection of Cu2+ based on dual‐emission ZIF‐8@rhodamine‐B nanocomposites

Zeolitic imidazolate framework‐8 (ZIF‐8) loading rhodamine‐B (ZIF‐8@rhodamine‐B) nanocomposites was proposed and used as ratiometric fluorescent sensor to detect copper(II) ion (Cu²⁺). Scanning electron microscopy, Fourier transform infrared spectroscopy, X‐ray powder diffraction, nitrogen adsorption/desorption isotherms and fluorescence emission spectroscopy were employed to characterize the ZIF‐8@rhodamine‐B nanocomposites. The results showed the rhodamine‐B was successfully assembled on ZIF‐8 based on the π‐π interaction and the hydrogen bond between the nitrogen atom of ZIF‐8 and –COOH of rhodamine‐B. The as‐obtained ZIF‐8@rhodamine‐B nanocomposites were octahedron with size about 150–200 nm, had good water dispersion, and exhibited the characteristic fluorescence emission of ZIF‐8 at 335 nm and rhodamine‐B at 575 nm. The Cu²⁺ could quench fluorescence of ZIF‐8 rather than rhodamine‐B. The ZIF‐8 not only acted as the template to assemble rhodamine‐B, but also was employed as the signal fluorescence together with the fluorescence of rhodamine‐B as the reference to construct a novel ratiometric fluorescent sensor to detect Cu²⁺. The resulted ZIF‐8@rhodamine‐B nanocomposite fluorescence probe showed good linear range (68.4 nM to 125 μM) with a low detection limit (22.8 nM) for Cu²⁺ combined with good sensitivity and selectivity. The work also provides a better way to design ratiometric fluorescent sensors from ZIF‐8 and other fluorescent molecules.     

Enhanced electrochemiluminescence from reduced graphene oxide–CdTe quantum dots for highly selective determination of copper ion

An electrochemiluminescence (ECL) sensor based on reduced graphene oxide–CdTe quantum dots (RGO–CdTe QDs) composites for detecting copper ion (Cu²⁺) was proposed. The ECL behaviours of the RGO–CdTe QD modified electrode were investigated with H₂O₂ as the co‐reactant. Quantitative detection of Cu²⁺ was realized as Cu²⁺ could effectively quench the ECL signal of the RGO–CdTe QDs. A wide linear range of 1.00 × 10^?14 to 1.00 × 10^?4 M (R = 0.9953) was obtained under optimized conditions, and a detection limit (S/N = 3) was achieved of as low as 3.33 × 10^?15 M. The proposed sensor also exhibited good stability and selectivity for the detection of copper ions. Finally, the analytical application of the proposed sensor was also evaluated using river water.     

A carbonothioate‐based highly selective fluorescent probe with a large Stokes shift for detection of Hg2+

Mercury (Hg) is one of the heavy metal pollutants in the environment. Even a very small amount of mercury can cause serious harm to human beings. Herein, we reported a new carbonothioate‐based fluorescent probe for the detection of Hg²⁺ without interference from other metal ions. This probe possessed a very large Stokes shift (192 nm), which could improve the detection sensitivity by minimizing the interferences resulted from self‐absorption or auto‐fluorescence. With the addition of Hg²⁺ to the probe solution, considerable fluorescence enhancement was observed. Additionally, the Hg²⁺ concentration of 0–16 μM and fluorescence intensity showed a good linear relationship (y = 22106× + 53108, R² = 0.9955). Finally, the proposed probe was used to detect Hg²⁺ in real water samples, and its result was satisfactory. Therefore, our proposed probe would provide a promising method for the determination of Hg²⁺ in the environment.     

A new rhodamine‐based fluorescent chemodosimeter for mercuric ions in water media

A new rhodamine–ethylenediamine–nitrothiourea conjugate (RT) was synthesized and its sensing property as a fluorescent chemodosimeter toward metal ions was explored in water media. Analytical results from absorption and fluorescence spectra revealed that the addition of Hg²⁺ ions to the aqueous solution of the chemodosimeter RT caused a distinct fluorescence OFF–ON response with a remarkable visual color change from colorless to pink; however, no clear spectral and color changes were observed from other metal ions including: Zn²⁺, Cu²⁺, Cd²⁺, Pb²⁺, Ag⁺, Fe²⁺, Cr³⁺, Co³⁺, Ni²⁺, Ca²⁺, Mg²⁺, K⁺ and Na⁺. The sensing results and the molecular structure suggested that a Hg²⁺‐induced a desulfurization reaction and cyclic guanylation of the thiourea moiety followed by ring‐opening of the rhodamine spirolactam in RT are responsible for a distinct fluorescence turn‐on signal, indicating that RT is a remarkably sensitive and selective chemodosimeter for Hg²⁺ ions in aqueous solution. Hg²⁺ within a concentration range from 0.1 to 25 μM can be determined using RT as a chemodosimeter and a detection limit of 0.04 μM is achieved. Copyright © 2014 John Wiley & Sons, Ltd.     

Determination of nucleic acid by [tetra‐(3‐methoxy‐4‐hydroxyphenyl)]–Tb3+ porphyrin as the fluorescence spectral probe in bis(2‐ethylhexyl)sulfosuccinate sodium salt micelle system

A new system for the determination of nucleic acid by rare earth metallic porphyrin of [tetra‐(3‐methoxy‐4‐hydroxyphenyl)]–Tb³⁺ [T(3‐MO‐4HP)–Tb³⁺] porphyrin as fluorescence spectral probe has been developed in this paper. Nucleic acid can enhance the fluorescence intensity of the T(3‐MO‐4HP)–Tb³⁺ porphyrin in the presence of bis(2‐ethylhexyl)sulfosuccinate sodium salt(AOT) micelle. In pH 8.00 Tris–HCl buffer solution, under optimum conditions, the enhanced fluorescence intensity is in proportion to the concentration of nucleic acids in the range of 0.05–3.00 µg mL^?1 for calf thymus DNA (ct DNA) and 0.03–4.80 µg mL^?1 for fish sperm DNA(fs DNA). Their detection limits are 0.03 and 0.01 µg mL^?1, respectively. In addition, the binding interaction mechanism between T(3‐MO‐4HP)–Tb³⁺ porphyrin and ct DNA is also investigated by resonance scattering and fluorescence spectra. The maximum binding number is calculated by molar ratio method. The new system can be used for the determination of nucleic acid in pig liver, yielding satisfactory results. Copyright © 2009 John Wiley & Sons, Ltd.     

Sensitive determination of DNA based on the interaction between prulifloxacin–terbium(III) complex and DNA

A simple spectrofluorimetric method is described for the determination of DNA, based on its enhancement of the fluorescence intensity of prulifloxacin (PUFX)–Tb³⁺. The luminescence intensity of the PUFX–Tb³⁺ complex increased up to 10‐fold after adding DNA. The excitation and emission wavelengths were 345 and 545 nm, respectively. Under optimum conditions, variations in the fluorescence intensity showed a good linear relationship with the concentration of hsDNA in the range of 3.0 × 10^‐9 to 1.0 × 10^‐6 g/mL, with a correlation coefficient (R) of 0.997, and the detection limit was 2.1 × 10^‐9 g/mL. The method was successfully applied to the determination of DNA in synthetic samples, and recoveries were in the range 97.3–102.0%. The mechanism of fluorescence enhancement of the PUFX–Tb³⁺ complex by DNA is also discussed. The mechanism may involve formation of a ternary complex mainly by intercalation binding together with weak electrostatic interaction, which will increase the energy transition from ligand to Tb³⁺, increasing the rigidity of the complex, and decreasing the radiationless energy loss through O–H vibration of the H₂O molecule in the PUFX–Tb³⁺ compl+osed method is not only more robust and friendly to the environment, but also of relatively higher sensitivity. Copyright © 2013 John Wiley & Sons, Ltd.