Selective Detection Of Lead Ions Research Articles

Towards sustainable and selective detection of lead Ions: Selaginella bryopteris assisted green synthesis of gold nanoparticles with tunable properties

The detection of highly toxic Pb2+ ions has propelled the exploration of green chemistry as an environmentally benign approach to synthesizing gold nanoparticles (AuNPs) for sensing applications. Herein, a simple green synthesis method is presented without utilizing optimization conditions for stable and well-disperse AuNPs for Pb2+ ions colorimetric sensing. The Selaginella bryopteris plant (SBp) extract as a reducing, capping, stabilizing, and chelating agent was employed in the volume ratio-controlled synthesis of AuNPs. The AuNPs were characterized using UV-Vis, XRD, FTIR, and TEM analysis. The results revealed polycrystalline AuNPs with SPR, particle size, and crystallite size-tunable by SBp extract. The AuNPs bound by Pb2+ ions showed immediate aggregation and excellent selectivity compared to other metal ions (Ca2+, Cd2+, Co2+, Cu2+, Fe2+, Hg2+, Mg2+, Mn2+, Ni2+, Zn2+, and Na+). A linear colorimetric response of AuNPs was observed in the 10–60 µM Pb2+ ions concentration range and the R2 obtained was 0.99654 with LoD of 0.24 µM. The best detection of Pb2+ ions was achieved in a pH range from 3 to 9. The study suggests that the SBp extract-tunable AuNPs synthesis could be used as a sustainable and simple approach for Pb2+ ions detection in the natural environment.

Synthesis of Imino Stabilized Iron Oxide Nanosensor for Selective Detection of Lead Ions

The present work describes the successful preparation of iron oxide nanoparticles (NSB1) stabilized with 4-((2-hydroxybenzylidene)amino)benzoic acid. The characterization has been achieved through ultraviolet visible (UV-Vis), fourier transform infra-red (FTIR) spectroscopy and scanning electron microscopy (SEM) with electron dispersive X-ray elemental analysis (EDX). These magnetic nanoparticles have exhibited significant chemosensing properties in the aqueous media to screen Cr3+, Cd2+, Li+, Co2+, Al3+, Pb2+, Ni2+ and Sr2+ ions. However, lead (Pb2+) ions have shown the highest selectivity as compared to other metal ions without any interference in the competitive ion study. The detection limit of Pb2+ ions was found to be 1.7 µM by this nanosensor. The binding ratio and stoichiometry was found to be 1:1 as measured by Job’s plot. The binding strength was also computed through Benesei-Hildebrand equation.

Design of a Novel Nanosensors Based on Green Synthesized CoFe2O4/Ca-Alginate Nanocomposite-Coated QCM for Rapid Detection of Pb(II) Ions.

Pb(II) is a significant contaminant that is known to have negative effects on both humans and animals. Recent industrial operations have exacerbated these consequences, and their release of several contaminants, including lead ions, has drawn attention to the potential effects on human health. Therefore, there is a lot of interest in the rapid, accurate, and selective detection of lead ions in various environmental samples. Sensors-based nanomaterials are a significant class among the many tools and methods developed and applied for such purposes. Therefore, a novel green synthesized cobalt ferrite (CoFe2O4) nanoparticles and functionalized CoFe2O4/Ca-alginate nanocomposite was designed and successfully synthesized for the fabrication of nanoparticles and nanocomposite-coated quartz crystal microbalance (QCM) nanosensors to detect the low concentrations of Pb(II) ions in the aqueous solutions at different temperatures. The structural and morphological properties of synthesized nanoparticles and nanocomposite were characterized using different tools such as X-ray diffraction (XRD), N2 adsorption–desorption isotherm, dynamic light scattering (DLS), zeta potential analyzer (ζ-potential), atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDX). The QCM results revealed that the green synthesized CoFe2O4 nanoparticles and functionalized CoFe2O4/Ca-alginate nanocomposite-coated QCM nanosensors exhibited high sensitivity, stability, and rapid detection of Pb(II) ions in the aqueous solutions at different temperature. The lowest detection limit for Pb(II) ions in the aqueous solutions could reach 125 ng, which resulted in a frequency shift of 27.49 ± 0.81, 23.63 ± 0.90, and 19.57 ± 0.86 Hz (Δf) for the QCM detector coated with green synthesized CoFe2O4 nanoparticles thin films, and 25.85 ± 0.85, 33.87 ± 0.73, and 6.87 ± 0.08 Hz (Δf) for the QCM detector coated with CoFe2O4/Ca-Alg nanocomposite thin films in a real-time of about 11, 13, and 13 min at 25 °C, 35 °C, and 45 °C, respectively. In addition, the resonance frequency change results showed the superiority of functionalized CoFe2O4/Ca-alginate nanocomposite coated QCM nanosensor over CoFe2O4 nanoparticles towards Pb(II) ions detecting, which attributed to the beneficial properties of alginate biopolymer.

(Invited) Real-Time, Selective Detection of Lead Ions in Water Using a Graphene-Based Field-Effect Transistor Sensing Platform

Water plays an important role in the economic world; only 3% of available water is potable, and with increasing demand, the need for safe drinking water is rising. The National Academy of Engineering identified “providing access to clean water” as one of the top 10 grand challenges for engineering in the 21st century. Heavy metal ions, e.g., lead, mercury, and arsenic, are widely present in water systems. These heavy metal ions are poisonous and may lead to serious damage to organs, tissues and bones, and nervous systems of humans. Existing water quality monitoring mostly occurs at the water supply intake or water treatment plant, instead of along water distribution lines and at the point of use, which is considered inadequate given potential changes in water quality and associated risks within water distribution systems. Current detection methods for aqueous heavy metal ions are often too expensive or unsuitable for in-situ and real-time detection (an unmet need). A field-effect transistor (FET) device-based sensor is developed to specifically detect Pb2+ ions in an aqueous environment. Reduced graphene oxide (rGO), as the semiconducting channel material, is utilized in the FET device through a self-assembly method. An L-glutathione reduced (GSH) is employed as the capture probe for the label-free detection. By monitoring the electrical characteristics of the FET device, the performance of the sensor is measured and investigated. Compared with conventional detection technologies, this sensor enables real-time detection with a response time of 1-2 seconds. A lower detection limit for Pb2+ ions as low as 10 nM is achieved, which is much lower than the maximum contaminant level (MCL) for Pb2+ ions in drinking water advised by the World Health Organization (WHO). Furthermore, the rGO FET sensor is able to distinguish Pb2+ from other metal ions. Without any sample pretreatment, the platform is user-friendly.

A turn-on near-infrared fluorescent chemosensor for selective detection of lead ions based on a fluorophore–gold nanoparticle assembly

A turn-on fluorescent chemosensor of Pb(2+) in the near-infrared (NIR) region, which is based on the Pb(2+)-tuned restored fluorescence of a weakly fluorescent fluorophore-gold nanoparticle (AuNPs) assembly, has been reported. In this fluorophore-AuNP assembly, NIR fluorescent dye brilliant cresyl blue (BCB) molecules act as fluorophores and are used for signal transduction of fluorescence, while AuNPs act as quenchers to quench the nearby fluorescent BCB molecules via electron transfer. In the presence of Pb(2+), fluorescent BCB molecules detached from AuNPs and restored their fluorescence due to the formation of a chelating complex between Pb(2+) and glutathione confined on AuNPs. Under the optimal conditions, the present BCB-AuNP assembly is capable of detecting Pb(2+) with a concentration ranging from 7.5 × 10(-10) to 1 × 10(-8) mol L(-1) (0.16-2.1 ng mL(-1)) and a detection limit of 0.51 nM (0.11 ng mL(-1)). The present BCB-AuNP assembly can be used in aqueous media for the determination of Pb(2+) unlike common organic fluorescent reagents, and also shows advantages of NIR fluorescence spectrophotometry such as less interference, lower detection limit, and higher sensitivity. Moreover, the present method was successfully applied for the detection of Pb(2+) in water samples with satisfactory results.

Avidin–biotin capped mesoporous silica nanoparticles as an ion-responsive release system to determine lead(II)

We have developed DNAzyme-functionalized silica nanoparticles for the rapid, sensitive, and selective detection of lead ion (Pb2+). The specific binding between avidin and biotinylated DNAzymes was used to cap the pore of dye-trapped silica nanoparticles. In the presence of Pb2+, DNAzymes were catalytically cleaved to uncap the pore, releasing the dye cargo with detectable enhancements of fluorescence signal. This method enables rapid (15min) and sensitive (limit of detection=8.0nM) detection. Moreover, the Pb2+-responsive behavior shows high selectivity with other metal ions. The superior properties of the as-designed DNAzyme-functionalized silica nanoparticles can be attributed to the large loading capacity and highly ordered pore structure of mesoporous silica nanoparticles as well as the catalytical cleaving of DNAzymes with Pb2+. The recoveries obtained by standard Pb(II) addition to real samples—tap water, commercial mineral water, and lake water—were all from 98 to 101%. Our design serves as a new prototype for metal–ion sensing systems, and it also has promising potential for detection of various targets in stimulus–release systems.

Highly sensitive dual-mode fluorescence detection of lead ion in water using aggregation-induced emissive polymers.

A series of fluorene-based conjugated polymers containing the aggregation-induced emissive (AIE)-active tetraphenylethene and dicarboxylate pseudocrown as a receptor exhibits a unique dual-mode sensing ability for selective detection of lead ion in water. Fluorescence turn-off and turn-on detections are realized in 80%-90% and 20% water in tetrahydrofuran (THF), respectively, for lead ion with a concentration as low as 10(-8) m.

DNA Wrapped Metallic Single-walled Carbon Nanotube Sensor for Pb (II) Detection

Based on the interaction of Pb (II) ions with nucleic acid via phosphate groups and nucleic bases of the deoxyribonucleic acid structure, an electrochemical sensor with DNA wrapped metallic single-walled carbon nanotube (SWNT) has been fabricated for sensitive and selective detection of lead ion (Pb2+). The sensor shows a rapid differential pulse voltammetry signal response to the content of Pb2+, and a quantitative detection of Pb2+ has been established with an expanded linear responsive range from 1 × 10−9 to 1.0 × 10−8 mol L−1 (R = 0.9979) and a detection limit of 4.1 × 10−10 mol L−1 in buffer solution (pH 5.0). Furthermore, the sensor displayed a negligible differential pulse voltammetry signal response for other metal ions, indicating its high selectivity for Pb2+. The investigation of electrochemical impedance spectroscopy and cyclic voltammetry in buffer solution demonstrated that metallic SWNTs played an important role in enlarging current response and increasing sensitivity of the sensor.

A highly sensitive and selective biosensing strategy for the detection of Pb2+ ions based on GR-5 DNAzyme functionalized AuNPs

In this paper, a novel fluorescence biosensing strategy based on GR-5 DNAzyme has been developed for the simple, rapid, sensitive and selective detection of lead ions (Pb2+) by using gold nanoparticles (AuNPs) as the fluorescence quencher. Data from dynamic light scattering (DLS) and zeta potential measurements demonstrated that GR-5 DNAzyme functionalized AuNPs were successfully prepared with good dispersion in aqueous solution. The carboxyfluorescein (FAM) labeled GR-5 DNAzyme was in close proximity to the AuNPs and the fluorescence signal was quenched, when the DNAzyme was modified on the surface of AuNPs. In the presence of Pb2+ ions, the GR-5 DNAzyme was activated and cleaved the substrate strand at the RNA site (rA) into two parts, which led to a short FAM-linked oligonucleotide fragment being released from the surface of the AuNPs, and the fluorescence intensity was gradually recovered. By taking advantage of the high fluorescence quenching efficiency of AuNPs, our proposed method exhibited a high sensitive detection of Pb2+ ions with a detection limit of 250 pM and a linear range from 1 nM to 100 nM. With the choice of a classic GR-5 DNAzyme instead of 8-17 DNAzyme as the catalytic unit, the selectivity of this strategy was obviously improved compared with previously reported methods. Moreover, this biosensing strategy was also used for the determination of Pb2+ in lake water samples with satisfying results. The strategy would find potential applications in environmental and biomedical fields.

A SERS DNAzyme biosensor for lead ion detection

SERS biosensor for sensitive and selective detection of lead ions (Pb(2+)) based on DNAzyme was developed by taking advantage of the specific catalytic reaction of DNAzyme upon binding to Pb(2+) ions. Detection was accomplished by SERS nanoprobe labeled with DNA and Raman reporters for signal amplification.

Label-free DNAzyme-based fluorescing molecular switch for sensitive and selective detection of lead ions

We developed a label-free fluorescent Pb(2+) sensor utilizing a DNAzyme-based fluorescing molecular switch, which enables fluorescence detection of Pb(2+) in aqueous solution with high sensitivity and selectivity.

Electrochemical DNAzyme Sensor for Lead Based on Amplification of DNA−Au Bio-Bar Codes

An electrochemical DNAzyme sensor for sensitive and selective detection of lead ion (Pb(2+)) has been developed, taking advantage of catalytic reactions of a DNAzyme upon its binding to Pb(2+) and the use of DNA-Au bio-bar codes to achieve signal enhancement. A specific DNAzyme for Pb(2+) is immobilized onto an Au electrode surface via a thiol-Au interaction. The DNAzyme hybridizes to a specially designed complementary substrate strand that has an overhang, which in turn hybridizes to the DNA-Au bio-bar code (short oligonucleotides attached to 13 nm gold nanoparticles). A redox mediator, Ru(NH3)6(3+), which can bind to the anionic phosphate of DNA through electrostatic interactions, serves as the electrochemical signal transducer. Upon binding of Pb(2+) to the DNAzyme, the DNAzyme catalyzes the hydrolytic cleavage of the substrate, resulting in the removal of the substrate strand along with the DNA bio-bar code and the bound Ru(NH3)6(3+) from the Au electrode surface. The release of Ru(NH3)6(3+) results in lower electrochemical signal of Ru(NH3)6(3+) confined on the electrode surface. Differential pulse voltammetry (DPV) signals of Ru(NH3)6(3+) provides quantitative measures of the concentrations of Pb(2+), with a linear calibration ranging from 5 nM to 0.1 microM. Because each nanoparticle carries a large number of DNA strands that bind to the signal transducer molecule Ru(NH3)6(3+), the use of DNA-Au bio-bar codes enhances the detection sensitivity by five times, enabling the detection of Pb(2+) at a very low level (1 nM). The DPV signal response of the DNAzyme sensor is negligible for other divalent metal ions, indicating that the sensor is highly selective for Pb(2+). Although this DNAzyme sensor is demonstrated for the detection of Pb(2+), it has the potential to serve as a general platform for design sensors for other small molecules and heavy metal ions.