Sensitive Pb2 Research Articles

Aptamer-functionalized gold nanoparticles for fast and selective electrochemical sensing of lead in tobacco

This study presents a novel electrochemical aptasensor for the ultrasensitive detection of lead(II) ions in tobacco products. The sensor utilizes a G-quadruplex forming DNA aptamer (5′-GGGTGGGTGGGTGGGT-3′) immobilized on gold nanoparticles (AuNPs) with an average diameter of 73.2 nm. The aptamer-Pb2+ interaction, characterized by circular dichroism and isothermal titration calorimetry, revealed a dissociation constant of 0.28 ± 0.03 μM. Optimized sensor fabrication conditions included 1 μM aptamer concentration and 16-h incubation time. The aptasensor exhibited two linear ranges: 0.2072–103.6 μg/L and 103.6–1072 μg/L, with a detection limit of 37 ng/L. The sensor maintained selectivity in the presence of interfering ions at 100-fold higher concentrations. The sensor demonstrated excellent stability, retaining 92.1 % of its initial response after 30 days, and high reproducibility with an inter-batch RSD of 5.3 %. This aptasensor offers a promising platform for rapid and sensitive Pb2+ detection in complex matrices.

Ultrasensitive Electrochemical Biosensors Based on Allosteric Transcription Factors (aTFs) for Pb2+ Detection.

Exposure to Pb2+ in the environment, especially in water, poses a significant threat to human health and urgently necessitates the development of highly sensitive Pb2+ detection methods. In this study, we have integrated the high sensitivity of electrochemical techniques with allosteric transcription factors (aTFs) to develop an innovative electrochemical biosensing platform. This biosensors leverage the specific binding and dissociation of DNA to the aTFs (PbrR) on electrode surfaces to detect Pb2+. Under the optimal conditions, the platform has a broad linear detection range from 1 pM to 10 nM and an exceptionally low detection threshold of 1 pM, coupled with excellent selectivity for Pb2+. Notably, the biosensor demonstrates regenerative capabilities, enabling up to five effective Pb2+ measurements. After one week of storage at 4 °C, effective lead ion detection was still possible, demonstrating the biosensor's excellent stability, this can effectively save the cost of detection. The biosensor also achieves a recovery rate of 93.3% to 106.6% in real water samples. The biosensor shows its potential as a robust tool for the ultrasensitive detection of Pb2+ in environmental monitoring. Moreover, this research provides new insights into the future applications of aTFs in electrochemical sensing.

Highly selective and sensitive Pb2+ detection via sulfur-doped graphitic carbon nitride modified by Bi nanospheres

The present-day human race is facing a series of environmental problems due to sewage discharge, excessive use of chemicals, mineral exploitation and so on, which are closely related to the rapid development of industries. The direct consequence is that the pollution of heavy metal ions is becoming more and more serious. It is very important to develop sensitive and efficient methods for detecting heavy metal ions. In this study, the nanocomposite of sulfur-doped graphitic carbon nitride (SCN) and Bi nanospheres (BiNSs) was prepared by thermal polycondensation reaction to introduce the sulfur into carbon nitride, followed by solvothermal method to realize the decoration of BiNSs. The SCN/BiNSs nanocomposite presents a highly selective and sensitive electrochemical detection capacity for Pb2+, derived from S-Pb strong bonding interaction and Bi-Pb binary alloy formation. The low detection limit of 0.07 μM could be achieved when the current response of Pb2+ was measured in the linear range of 0.1 μM − 4.5 μM by square wave anodic stripping voltammetry. The detection of Pb2+ in actual water specimens led to a recovery rate varied from 88 to 123 %. Further, in the presence of 20-fold interfering ions such as Zn2+, Fe3+, Cd2+, Cu2+, Fe2+ and Ni2+, the SCN/BiNSs-modified electrode still possesses excellent immunity and selectivity. Meanwhile, the remarkable stability, repeatability and reproducibility of the above sensing electrode have also been demonstrated. Our primary results show that the SCN/BiNSs nanocomposite holds great potential for practical application for Pb2+ detection.

Magnetic DNAzyme nanomachine fluorescent biosensor for Pb(Ⅱ) detection

The lead ion (Pb2+) is harmful to human. Detecting low content of Pb2+ in the environment requires high sensitive and specific detection technology. In this study, we developed a magnetic DNAzyme nanomachine fluorescent biosensor for rapid and ultra-sensitive detection of Pb2+. We focused on using bovine serum albumin (BSA) as a bridge to connect magnetic beads and DNAzyme in the magnetic nanomachine, aiming to improve the detection sensitivity. In the presence of Pb2+, the enzyme cleavage activity was activated, leading to the substrate chains cleaved and released. Meanwhile, Pb2+ participated in the cyclic process of recognition and release, which contributed to signal amplification. The cleavage products and stem-loop chains were assembled and amplified using the double primer realtime fluorescence quantitative reaction (qPCR) method. By applying such triple amplifications of the signal, Pb2+ was quantitatively detected by measuring the change in the Ct value (ΔCt) before and after cleavage of the DNAzyme. Under optimized assay conditions, a linear relationship ranging from 2 nM to 150 nM was observed with a limit of detection (LOD) of 3.7 nM for Pb2+. In conclusion, our approach offers a potentially useful method for simple, rapid, and sensitive Pb2+ detection.

Dual-functional DNAzyme powered CRISPR-Cas12a sensor for ultrasensitive and high-throughput detection of Pb2+ in freshwater

Freshwater lead pollution has posed severe threat to the environment and human health, underscoring the urgent necessity for accurate and user-friendly detection methods. Herein, we introduce a novel Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR-Cas) sensor for highly sensitive Pb2+ detection. To accomplish this, we designed a dual-functional deoxyribozyme (df-DNAzyme) probe that functions as an activator for the CRISPR-Cas12a system while also recognizing Pb2+. The df-DNAzyme probe was subsequently combined with gold nanoparticles (AuNPs) to fabricate a DNAzyme/AuNP nanoprobe, facilitating the activation of CRISPR-Cas12a in a one-to-multiple manner. Upon exposure to Pb2+, the df-DNAzyme is cleaved, causing disintegration of the DNAzyme/AuNP nanoprobe from magnetic beads. The degraded DNAzyme/AuNP containing multiple double-stranded DNA activators efficiently triggers CRISPR-Cas12a activity, initiating cleavage of fluorescence-quenched reporter DNA and generating amplified signals accordingly. The amplified fluorescence signal is accurately quantified using a quantitative polymerase chain reaction (qPCR) instrument capable of measuring 96 or 384 samples simultaneously at the microliter scale. This technique demonstrates ultra-sensitive detection capability for Pb2+ at concentrations as low as 1 pg/L within a range from 1 pg/L to 10 μg/L, surpassing limits set by World Health Organization (WHO) and United States Environmental Protection Agency (US EPA) guidelines. This study offers an ultrasensitive and high-throughput method for the detection of Pb2+ in freshwater, thereby advancing a novel approach towards the development of precise and convenient techniques for detecting harmful contaminants.

Selective detection of Pb2+ ions based on a graphene field-effect transistor gated by DNAzymes in binding mode

Heavy metal contamination has become a severe threat to dairy products through contaminated feed and the environment water. Among them, Pb(II) is highly toxic to the human body even under minimal exposure. Therefore, establishing a fast and sensitive Pb2+ detection technology is significant for rapid screening of vast number of dairy products. Hererin, we report the development of a sensitive and selective Pb(II) biosensor based on a solution-gated graphene transistor (SGGT) with the gate modified by Pb2+-dependent DNAzyme probes. It has also been explored that the DNAzymes working in simple binding mode integrate better with the SGGT than those working in normal catalytic mode, showing significantly stronger channel current responses and lower detection limit down to 0.39 μg/L (or 1.9 nM). Finally, the biosensor was practicably applied to the detection of lead ions in pure milk samples with a high recovery rate. We believe that this work reveals the best strategy for integrating metal ion dependent DNAzyme probes with SGGT sensing platforms to selectively and sensitively detect many metal ions.

Ultralow background one-pot detection of Lead(II) using a non-enzymatic double-cycle system mediated by a hairpin-involved DNAzyme

A double-cycle system has been developed for specifically detecting trace amounts of Pb2+ by significantly decreasing the background signal. The detection involves two types of RNA cleavage reactions: one using a Pb2+-specific GR5 DNAzyme (PbDz) and the other utilizing a newly constructed 10–23 DNAzyme with two hairpins embedded in its catalytic center (hpDz). The ring-structured hpDz (c-hpDz) exhibits significantly lower activity compared to the circular 10–23 DNAzyme without hairpin structures, which plays a crucial role in reducing the background signal. When Pb2+ is present, PbDz cleaves c-hpDz to its active form, which then disconnects the molecular beacon to emit the fluorescent signal. The method allows for rapid and sensitive Pb2+ detection within 40 min for 10 fM of Pb2+ and even as short as 10 min for 100 nM of Pb2+. Additionally, visual detection is possible through the non-crosslinking assembly of Au nanoparticles. The entire process can be performed in one pot and even one step, making it highly versatile and suitable for a wide range of applications, including food safety testing and environmental monitoring.

Nanohybrid of antimonene@Ti3C2Tx-based electrochemical aptasensor for lead detection

Lead ions (Pb2+), as one of many common heavy metallic environmental pollutants, can cause serious side-effects and result in chronic poisoning to people's health, so it is highly significant to monitor Pb2+ efficiently and sensitively. Here, we proposed an antimonene@Ti3C2Tx nanohybrid-based electrochemical aptamer sensor (aptasensor) for high sensitive Pb2+ determination. The sensing platform of nanohybrid was synthesized by ultrasonication, possessing the advantages of both antimonene and Ti3C2Tx, which not only can vastly enlarge the sensing signal of the proposed aptasensor, but also greatly simplified its manufacturing flow, because antimonene can strongly interact with aptamer through noncovalently bound. The surface morphology and microarchitecture of the nanohybrid were perused by several methods such as scanning electron microscope (SEM), energy-dispersive X-ray mapping spectroscopy (EDS), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and atomic force microscope (AFM). Under optimal empirical conditions, the proposed aptasensor exhibited a wide linear correlation of the current signals with the logarithm of CPb2+ (Log CPb2+) over the span from 1 × 10−12 to 1 × 10−7 M and provided a trace discernment limit of 3.3 × 10−13 M. Moreover, the constructed aptasensor displayed superior repeatability, great consistency, eminent selectivity, and beneficial reproducibility, implying its extreme potential application for water quality control and the environmental monitoring of Pb2+.

Highly selective and sensitive fluorescent probe possessing AIEE and ICT properties for rapid detection of Pb2+ in aqueous medium and its applications in living cells.

In this paper, a novel rapid, highly selective and sensitive Pb2+ fluorescent probe (E)-N'-((2-(4'-(diphenylamino)-[1,1'-biphenyl]-4-yl)-2H-1,2,3-triazol-4-yl)methylene) (DBTBH) was synthesized. The probe DBTBH not only exhibited more excellent selectivity and sensitivity to Pb2+ detection compared with other analytes (include metal ions and anions) in H2 O:THF solution (v:v = 9:1, 10 mM Tris-HCl, 1 mM KI, pH 7.4), but also had excellent optical properties such as aggregation-induced emission enhancement (AIEE) and intramolecular charge transfer (ICT). Detection limit of the probe DBTBH towards Pb2+ was 4.49 × 10-8 M. The possible mechanism was verified by 1 H NMR titration and HR-MS. Furthermore, the successful detection of Pb2+ by DBTBH in real water samples and HeLa cells indicated that DBTBH has great potential for selective recognition of Pb2+ in the natural environment and biological systems. These findings will provide a promising new idea for designing better Pb2+ fluorescent probes in the future.

TiO2 Nano-test tubes as a solid visual platform for sensitive Pb2+ ion detection based on a fluorescence resonance energy transfer (FRET) process.

A cost-effective, facile, and sensitive fluorescence sensing strategy for Pb2+ ion detection has been developed based on the fluorescence resonance energy transfer (FRET) between carbon quantum dots (CQDs) and Au nanoparticles (NPs). Glutathione (GSH)-synthesized CQDs acted as both the fluorescence donor and the sorbent to extract Pb2+ ions from the solution via Pb-GSH complexes. Pb2+ ions on CQDs reacted with -SH groups on AuNPs to generate sandwich-type Au-PdS-CQDs, leading to a dramatic decrease in the fluorescence of the CQDs. To expand the potential applications of this strategy, we constructed a sensing strategy using self-organized TiO2 nanotube arrays (TiNTs). The high aspect ratio and transparency for light emitted from the CQDs enabled the TiNTs to serve as a sensitive solid visual platform for the highly selective detection of Pb2+ ions with a detection limit as low as 4.1 × 10-8mgmL-1. More importantly, the long observation length combined with a small volume enabled a sample acquisition volume of only 2.1 × 10-3μL, which is smaller than the traditional fluorescence analysis in solution and on commercially available test paper, thus endowing this visual platform with the potential for use in single-cell diagnostics.

Highly sensitive Pb2+ sensor based on rod-like poly-tyrosine/Bi modified glassy carbon electrode combined with electrodeposition to eliminate Cu2+ interference

A rod-like poly-tyrosine membrane modified glassy carbon electrode (p-Tyr/GC) was first prepared and characterized by CV, EIS and SEM, which can improve electroactive area and electron transfer. Then a Bi/p-Tyr/GC composite electrode was prepared by in situ Bi plating. Taking the Bi/p-Tyr/GC’s response to 0.25 μmol·L−1 Pb2+ as reference, the optimal conditions for Bi/p-Tyr/GC preparation and test were obtained with Tyr concentration, scan number, Bi3+ concentration, pH and accumulation potential being 2.0 mmol·L−1, 20, 3.0 μmol·L−1, 6.5 and −1.3 V, respectively. Under optimal conditions, the linear equation of Bi/p-Tyr/GC’s response to Pb2+ (1.0 nmol·L−1 to 3.0 μmol·L−1) was ip (μA) = 0.6184 + 105.5c (μmol·L−1) (R2 = 0.9987) with a detection limit of 0.12 nmol·L−1 (3S/k). For the first time, the elimination of Cu2+ interference for Pb2+ determination was studied by electrodeposition. The Bi/p-Tyr/GC electrode was successfully used for Pb determination in preserved duck eggs with a recovery of 92.1–97.9% and RSD less than 3.5%. The developed Pb2+ sensor has high sensitivity and wide linear range. More importantly, the electrochemical method for eliminating Cu2+ interference has high selectivity and wide application range, which has important reference value for the development of other heavy metal ion sensors in complex samples.

Sensitive electrochemical platform for trace determination of Pb2+ based on multilayer Bi-MOFs/reduced graphene oxide films modified electrode.

A multilayer Bi-BTC/reduced graphene oxide (Bi-BTC/rGO) (BTC, 1,3,5-benzenetricarboxylic acid) film electrode was adopted to construct a highly sensitive Pb2+ electrochemical sensor. The multilayer Bi-BTC/rGO films were prepared via alternate cast of Bi-BTC and graphene oxide (GO) on a glassy carbon electrode, followed by electro-reduction of the GO components. Bi-BTC has porous broom-like structure and its organic ligand has abundant functional groups, which are favorable for Pb2+ adsorption and preconcentration. The introduction of rGO layer improves the conductivity of the MOFs material. Moreover, the multilayer composite structure greatly increased the exposure of active sites and the surface area of reactive contact, finally realizing the highly sensitive detection of Pb2+. Pb2+ was determined by differential pulse anodic stripping voltammetry and the response current was recorded at - 0.62V. The [Bi-BTC/rGO]2 electrode provides a wide linear response ranging from 0.062 to 20.72μg/L and a low limit of detection (LOD) of 0.021μg/L (S/N = 3) for Pb2+, which is lower than the guideline value proposed by the World Health Organization. The method has been applied to determine Pb2+ in industrial wastewater with recoveries of 99.2-104% and RSDs of 3.4-4.0% (n= 3). Graphical abstract Graphical abstract Schematic representation of an electrochemical sensor for the detection of Pb2+ was designed based on long broom-like structure bismuth(II) metallic organic framework/reduced graphene oxide ([Bi-BTC /rGO]2).

An “on-off” electrochemiluminescence biosensor based on DNA nanotweezer probe coupled with tripod capture DNA for high sensitive detection of Pb2+

In this work, a new DNA nanotweezers-Ag nanoparticle (NP) as signal-switching probe is designed and coupled with tripod-like capture DNA structure to construct an ultrasensitive “ON-OFF” electrochemiluminescence (ECL) biosensor for detecting Pb2+. The unique tweezer nanostructure has two G-base-rich sequences on different arms, and the G4-chain structure is simply constructed by switching tweezer conformation from “open” to “close”, which can be controlled by alternative target released in Pb2+-triggered cyclic amplification process. The activated G4-structure can specifically capture plenty of hemin to the closed state, which has a strong quenching effect on ECL of Ru(phen)32+. After reduced graphene oxide (ERGO) with good electrochemical activity and loading capacity is electrodeposited on the electrode, Ru(phen)32+ as ECL probe is strongly adsorbed on it via π-π conjugation. Then tripod-like DNA structure with spiral extensibility, good capabilities, and no backfilling was linked to the surface to capture G4-structure with hemin, resulting in significant decrease of ECL for sensitive Pb2+ detection. Due to the design flexibility of DNA nanotweezers structure, the strategy provides universal design of ECL biosensors in ingenious assay of a variety of metal ions and other bioassays.

Selective and sensitive detection of lead Pb(II) ions: Au/SWNT nanocomposite-embedded MOF-199

Metal organic frameworks (MOFs) are best known for their highly crystalline structures, ultrahigh porosity with considerable surface area and tunable physicochemical properties. The promising architecture of MOFs, where central metal atoms are surrounded by organic ligands secures their prominent candidature for advanced sensor technology. In this work, we have synthesized gold (Au) nanoparticles and single-walled carbon nanotube (SWNTs) nanocomposite-incorporated copper benzene tricarboxylate (MOF-199) MOF (Au/SWNTs@MOF-199) by solvothermal route. The synthesized Au/SWNTs@ MOF-199 has rigorously characterized with spectroscopic, morphological, structural, electrochemical, thermal, Brunauer–Emmett–Teller (BET) surface area using N2 adsorption isotherm methods. The proposed Au/SWNTs@MOF-199 nanocomposite exhibited excellent electrochemical characteristics and sensing performance towards Pb2+ ions. The calibration plot for the electrochemical response of Au/SWNTs@MOF-199 towards Pb2+ ions was recorded for the range of 0.1 mM–1 pM (R2 = 99.58)) with a limit of detection of 25 pM/L and a rapid response time of a few seconds with high sensitivity, selectivity, repeatability and reproducibility as determined by error bar diagram. These results indicate the significant potential of Au/SWNTs@MOF-199 nanocomposites as highly sensitive Pb2+ ion sensor.

Core-shell Ag @ ZIF-8 nanowires as high sensitive signal generation probes for on-line detection of Pb2+

The key to improve the detection performance is to select the analysis device preparation procedure according to the type of analyte. Herein, based on the prepared fully-wrapped core-shell Ag@ZIF-8 nanowires (NWs), a novel sensitive Pb2+ sensor of Ag@ZIF-8 NWs was prepared by in-situ film-forming on quartz crystal microbalance (QCM) by a simple drop-casting method. The Ag@ZIF-8 NWs modified QCM showed on-line detection of Pb2+ ranging from 0.1 μmol/L to 10000 μmol/L, accompanied by a lower detection limit of 10 nmol/L. In addition, the prepared sensor is equipped with high excellent selectivity to Pb2+. This suggested tactic may offer train of thought for detection of other heavy metal ions.

Sustainable carbon dots as “turn-off” fluorescence sensor for highly sensitive Pb2+ detection

Sustainable carbon dots as “turn-off” fluorescence sensor for highly sensitive Pb2+ detection

Fabrication of selective and sensitive Pb2+ detection by 2,2′-(−(1,2-phenylenebis(azaneylylidene))bis(methaneylylidene))diphenol by electrochemical approach for environmental remediation

The Tetradentate Schiff base was easily prepared from o-phenylenediamine and salicylaldehyde and used as a ligand for the detection of heavy metal ions in phosphate buffer medium by electrochemical approach. To fabricate the selective lead (Pb2+) ion sensor, a slurry of the synthesized 2,2′-(−(1,2-phenylenebis(azaneylylidene))bis(methaneylylidene))diphenol (TDL) ligand was deposited onto glassy carbon electrode (GCE) as uniform thin-layer. The calibration curve of the proposed Pb2+ ion sensor in form of a current vs. concentration plot is found to be linear over Pb2+ ion concentration range (0.1 nM ~ 0.01 mM). The sensitivity of the sensor is very high (8.84 μAμM−1 cm−2) and detection limit is as low as 98.02 ± 0.50 pM (Limit of quantification is 316.73 pM). The projected Pb2+ sensor with active TDL shows reliability, precise reproducibility and short response time (16.0 s.) during sensing performances. Above all, it was showed successive applicability to detect the real environmental samples. In the field sensor development, this methodology using TDL onto GCE might be ae efficient and reliable innovative technique for the detection of heavy metal ions by electrochemical methods.

Methylene blue sensitized photoelectrochemical biosensor with 3,4,9,10-Perylene tetracarboxylic acid film as photoelectric material for highly sensitive Pb2+ detection

It is of great significance to explore reliable and sensitive methods for the trace detection of lead ions (Pb2+), which may cause serious adverse effect to human health. Herein, we proposed a methylene blue (MB) sensitized signal-on photoelectrochemical (PEC) biosensor with 3,4,9,10-perylene tetracarboxylic acid (PTCA) film as photoelectric material for highly sensitive Pb2+ detection. First, PTCA was modified on the electrode surface, manifesting wonderful film-forming property and acquiring a satisfactory initial PEC signal. Afterward, Pb2+-dependent DNAzyme modified on electrode was cleaved by target Pb2+, followed by hybridizing MB assembled 3D DNA networks with the exposed Pb2+ catalytic strand. Significantly, in the presence of sensitizer MB, the PEC signal of PTCA was extraordinarily increased and the designed biosensor performed a high sensitivity with a detection limit down to 0.03 pM. Therefore, with enzyme-free assembly of MB embedded 3D DNA networks, this dye-sensitized strategy exhibited effective and uncomplicated amplification technology for Pb2+ detection.

3D origami electrochemical device for sensitive Pb2+ testing based on DNA functionalized iron-porphyrinic metal-organic framework

A highly sensitive electrochemical (EC) biosensor combined with a 3D origami device for detection of Pb2+was developed based on novel Au nanoparticles modified paper working electrode (Au-PWE) as sensor platform and DNA functionalized iron-porphyrinic metal-organic framework ((Fe-P)n-MOF-Au-GR) hybrids as signal probes. In the presence of Pb2+, GR could be specifically cleaved at the ribonucleotide (rA) site, which produced the short (Fe-P)n-MOF-linked oligonucleotide fragment to hybridize with hairpin DNA immobilized on the surface of Au-PWE. Because of the mimic peroxidase property of (Fe-P)n-MOF, enzymatically amplified electrochemical signal was obtained to offer the sensitive detection of Pb2+. In addition, benefiting from the Pb2+ dependent GR, the proposed assay could selectively detect Pb2+ in the presence of other metal ions. This method showed a good linear relationship between the current response and the Pb2+ concentration ranging from 0.03 to 1000nmolL−1 with a detection limit of 0.02nmolL−1. The Au-PWE based electrochemical sensor along with the (Fe-P)n-MOF-Au-GR probe exhibited the advantages of low-cost, simple fabrication, high sensitivity and selectivity, providing potential application of real-time Pb2+ detection both in environmental and biological samples.

Direct imaging of single gold nanoparticle etching: sensitive detection of lead ions

We present a highly sensitive Pb2+ detection method by in situ real-time imaging of Pb2+ catalyzed etching and size reduction of immobilized single gold nanoparticles with darkfield microscopy.