Electrochemical Aptasensor Based on Sulfur-Nitrogen Codoped Ordered Mesoporous Carbon and Thymine-Hg2+-Thymine Mismatch Structure for Hg2+ Detection

Preparation of CoFe@C composite modified electrode for neohesperidin dihydrochalcone sensing and its application in Chinese medicine

CoFe@C was first prepared by calcining the precursor of CoFe-metal-organic framework-74 (CoFe-MOF-74), then an electrochemical sensor for the determination of neohesperidin dihydrochalcone (NHDC) was constructed, which was stemmed from the novel CoFe@C/Nafion composite film modified glassy carbon electrode (GCE). The CoFe@C/Nafion composite was verified by field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). Electrochemical impedance spectroscopy (EIS) was used to evaluate its electrical properties as a modified material for an electrochemical sensor. Compared with CoFe-MOF-74 precursor modified electrode, CoFe@C/Nafion electrode exhibited a great synergic catalytic effect and extremely increased the oxidation peak signal of NHDC. The effects of various experimental conditions on the oxidation of NHDC were investigated and the calibration plot was tested. The results bespoken that CoFe@C/Nafion GCE has good reproducibility and anti-interference under the optimal experimental conditions. In addition, the differential pulse current response of NHDC was linear with its concentration within the range 0.08 ~ 20 µmol/L, and the linear regression coefficient was 0.9957. The detection limit was as low as 14.2 nmol/L (S/N = 3). In order to further verify the feasibility of the method, it was successfully used to determine the content of NHDC in Chinese medicine, with a satisfactory result, good in accordance with that of high performance liquid chromatography (HPLC).

Sandwich-type immunosensor based on aminated 3D-rGOF-NH2 and CMK-3-Fc-MgAl-LDH multilayer nanocomposites for detection of CA125

Cancer antigen 125 (CA125)1 is the most important biological screening indicator used to monitor epithelial ovarian cancers, and it plays a vital role in distinguishing ovarian cancers from benign diseases. Biosensors show great potential in the analysis and detection of disease markers. In this study, we designed electrochemical sensors based on three-dimensional amino-functionalized reduced graphene oxide (3D-rGOF-NH2),2 MgAl layered double hydroxide nanocomposites containing ordered mesoporous carbon (CMK-3),3 and ferrocene carboxylic acids（Fc-COOH）4for the detection of CA125. 3D-rGOF-NH2 possesses good conductivity, a large surface area, and high porosity, enabling more immobilized nanoparticles to be deposited on its surface with excellent stability. CMK-3@Fc@MgAl-LDH nanocomposite was used as a carrier to enhance the immobilization of antibodies and the loading of Fc, conductors to enhance conductivity, and enhancers to gradually amplify the signal of Fc. The surface morphology, elemental composition, and surface groups of the materials were characterized using scanning electron microscopy (SEM),5 transmission electron microscopy (TEM),6 and X-ray diffraction (XRD)7 techniques. The response signal of the electrochemical sensor was measured by DPV. Under the optimal conditions, the electrochemical sensor obtained a linear detection range of 0.01 U/mL-100 U/mL with a detection limit of 0.00417 U/mL.

Unique three-dimensional ordered macroporous dealloyed gold-silver electrochemical sensing platforms for ultrasensitive mercury(II) monitoring

To address the requirement of ultra-sensitive detection of trace mercury(II) (Hg2+) ions in the environment and food, we developed an electrochemical biosensor with super-sensitivity, extremely high selectivity, and reusability. This biosensor comprised two signal amplification components: a three-dimensional macroporous dealloyed (3DOMD) Au-Ag thin-film electrode and a multifunctional encoded Au@Pt nanocage (APNC). As a platform for immobilized capture DNA (cDNA), a 3DOMD Au-Ag thin film prepared by a dealloying method with an active surface area 4.8 times higher than that of 3D macroporous gold films generated by cyclic voltammetry (CV) with sulfuric acid was capable of increasing the sensing surface area while also strengthening the electron transport capacity of the sensing substrate due to its multilayered multi-porous framework. In the presence of Hg2+, probe DNA (pDNA) could be hybridized with the mismatched capture DNA (cDNA) through stable thymine-Hg2+-thymine (T-Hg2+-T) linkages, connecting thionine-APNC to the electrode surface and utilizing the large specific surface area to accomplish highly sensitive detection of Hg2+. With an extremely low Hg2+ detection limit of 2 pM and a detection range from 0.01 to 1000 nM, this technique opened up a new avenue for the ultrasensitive detection of a wider range of heavy metal ions or biomolecules.

A colorimetric detection of Hg2+ based on gold nanoparticles synthesized oxidized N-methylpyrrolidone as a reducing agent

In this study, a gold nanoparticles colorimetric probe (AuNPs) with direct response to mercury ions (Hg2+) were developed using treated N-methylpyrrolidone (NMP) and chloroauric acid (HAuCl4) as precursors. NMP showed good reducibility after high temperature hydrolysis and could be used as reducing and stabilizing agent to synthesize AuNPs. The prepared AuNPs have obvious characteristic absorption peaks and appear wine-red. At the same time, it was found that the presence of Hg2+ can cause the aggregation of AuNPs, increased the absorbance at 700 nm, and changed the color of the solution into blue-gray. This method is capable of sensitive and specific determination of Hg2+ ranging from 1 to 30 μM, with the limit of detection (LOD) at 0.3 μM. The method showed good specificity for the determination of Hg2+ and has the potential to be applied to Hg2+ detection in sewage samples in the environment.

Synthesis of magnetic sodium lignosulfonate hydrogel(Fe3O4@LS) and its adsorption behavior for Cd2+ in wastewater

Heavy metal pollution is becoming increasingly serious. Heavy metal pollutants are nonbiodegradable and can be bioenriched through the food chain, and thus, they greatly threaten the environment and human health. Hydrogels, as an ideal adsorbent, have been widely used to treat heavy metal industrial wastewater. Sodium lignosulfonate hydrogel (LS) was prepared by free-radical grafting copolymerization, and nano-Fe3O4 particles were loaded in LS by an in-situ precipitation method (Fe3O4@LS). The magnetic properties and adsorption capacity of Fe3O4@LS are closely related to the load capacity of Fe3O4. XRD, FTIR, XPS, SEM, TEM, BET, and TGA analyses of the materials were performed. Subsequently, the removal effect of the typical pollutant Cd2+ in heavy metal-polluted water was studied with Fe3O4@LS as the adsorbent. The influences of the Fe3O4@LS dosage and initial pH were investigated, and the adsorption kinetics and thermodynamics were further explored and discussed. Finally, the adsorption mechanism of Fe3O4@LS on Cd2+ was obtained. Results show that Fe3O4@LS has a more stable spatial network structure than LS, and the pore size, specific surface area and active sites increase. The maximum adsorption capacity can reach 88.00 mg/g when pH = 6 and the dosage of Fe3O4@LS is 1000 mg/L. The adsorption of Cd2+ by Fe3O4@LS conforms to pseudosecond-order kinetics and the Temkin isothermal adsorption model. Further mechanistic investigations show that the sorption of Cd2+ on Fe3O4@LS is mainly attributed to surface complexation, electrostatic attraction and coprecipitation. The coexistence of cations in water will inhibit the adsorption of Fe3O4@LS. Fe3O4@LS has superparamagnetism and a good response to an external magnetic field. The adsorption rate can still reach >60 % after four elutions with NaCl as the eluent. This material can be reused and has good application potential.

Colorimetric method transforms into highly sensitive homogeneous voltammetric sensing strategy for mercury ion based on mercury-stimulated Ti3C2Tx MXene nanoribbons@gold nanozyme activity

Nanozymes were emerged as the next generation of enzyme-mimics which exhibit great applications in various fields, but there is rarely report in the electrochemical detection of heavy metal ions. In this work, Ti₃C₂T_x MXene nanoribbons@gold (Ti₃C₂T_x MNR@Au) nanohybrid was prepared firstly via a simple self-reduction process and its nanozyme activity was studied. The results showed the peroxidase-like activity of bare Ti₃C₂T_x MNR@Au is extremely weak, while in the presence of Hg²⁺, the related nanozyme activity is stimulated and improved remarkably, which can easily catalyze oxidation of several colorless substrates (e.g., o-phenylenediamine) to form colored products. Interestingly, the product of o-phenylenediamine exhibits a strong reduction current which is considerably sensitive to the Hg²⁺ concentration. Based on this phenomenon, an innovative and highly sensitive homogeneous voltammetric (HVC) sensing strategy was then proposed to detect Hg²⁺ via transforming the colorimetric method into electrochemistry since it can exhibit several unique advantages (e.g., rapid responsiveness, high sensitivity and quantificational). Compared to the conventional electrochemical sensing methods for Hg²⁺, the designed HVC strategy can avoid the modification processes of electrode coupled with enhanced sensing performances. Therefore, we expect the as-proposed nanozyme-based HVC sensing strategy provides a new development direction for detecting Hg²⁺ and other heavy metals.

Constructing functional metal-organic frameworks by ligand design for environmental applications

Metal-organic frameworks (MOFs) with unique physical and chemical properties are composed of metal ions/clusters and organic ligands, including high porosity, large specific surface area, tunable structure and functionality, which have been widely used in chemical sensing, environmental remediation, and other fields. Organic ligands have a significant impact on the performance of MOFs. Selecting appropriate types, quantities and properties of ligands can well improve the overall performance of MOFs, which is one of the critical issues in the synthesis of MOFs. This article provides a comprehensive review of ligand design strategies for functional MOFs from the number of different types of organic ligands. Single-, dual- and multi-ligand design strategies are systematically presented. The latest advances of these functional MOFs in environmental applications, including pollutant sensing, pollutant separation, and pollutant degradation are further expounded. Furthermore, an outlook section of providing some insights on the future research problems and prospects of functional MOFs is highlighted with the purpose of conquering current restrictions by exploring more innovative approaches.

A pH-Stable TbIII-Based Metal-Organic Framework as a Turn-On and Blue-Shift Fluorescence Sensor toward Benzaldehyde and Salicylaldehyde in Aqueous Solution

A new polydentate tetracarboxylic acid with a benzothiadiazole unit (4',4'''-(benzo[c][1,2,5]thiadiazole-4,7-diyl)bis([1,1'-biphenyl]-3,5-dicarboxylic acid), H₄BTDBA) has been used to prepare a pH-stable three-dimensional Tb^III-based metal-organic framework (MOF) with the formula {[(CH₃)₂NH₂]_0.7[Tb₂(BTDBA)_1.5(lac)_0.7(H₂O)₂]·solvents}_n (Hlac = lactic acid, JXUST-19). JXUST-19 exhibits a new (4,4,12)-connected topology based on tetranuclear [Tb₄] clusters. JXUST-19 can remain stable when soaked in water for at least 1 week and in aqueous solutions with various pH values (2-12) for 24 h. Fluorescence study indicates JXUST-19 can be employed as a rare turn-on and blue-shift MOF sensor toward benzaldehyde (BZ) and salicylaldehyde (SA). To date, JXUST-19 represents the first Tb^III-based turn-on MOF sensor toward salicylaldehyde in aqueous solution, and the fluorescence enhancement and naked-eye detection of BZ have been rarely reported. In addition, JXUST-19 based fluorescent test papers, light-emitting diode lamp beads, and portable composite films were developed to realize naked-eye detection of BZ and SA, which has great potential in practical applications.

A nucleic acid dye-enhanced electrochemical biosensor for the label-free detection of Hg2+ based on a gold nanoparticle-modified disposable screen-printed electrode

In this paper, a nucleic acid dye-enhanced electrochemical biosensor based on a screen-printed carbon electrode (SPCE) modified with Au nanoparticles (AuNPs) was designed for the detection of Hg²⁺ in water. AuNPs were modified on the surface of the disposable SPCE through the electrodeposition of HAuCl₄. Subsequently, thiolated DNA probes were immobilized on the AuNP-modified electrode surface by Au-S reaction. After Hg²⁺ was bound with a DNA probe by thymine (T)-Hg²⁺-thymine (T) mismatch, the DNA probe was folded into a hairpin structure where positively charged GelRed molecules were embedded into the double-stranded part of the hairpin. Thus, the current of [Fe(CN)₆]^3-/4- increased significantly on account of the decreased electrostatic repulsion at the electrode surface. Under the optimized experimental conditions, the peak current of [Fe(CN)₆]^3-/4- exhibited a good linear relationship with lgC_Hg²⁺ in the concentration of Hg²⁺ linear range of 0.1 nM to 500 nM, and the limit of detection (S/N = 3) was calculated as 0.04 nM. The electrochemical sensor also exhibited excellent selectivity for Hg²⁺ in the presence of nine interfering ions, including Na⁺, Fe³⁺, Ni²⁺, Mg²⁺, Co²⁺, Pb²⁺, K⁺, Al³⁺ and Cu²⁺. Meanwhile, the developed electrochemical sensor was tested in the analysis of Hg²⁺ in tap water and river water samples, and the recoveries ranged from 81.0 to 114%. Therefore, this nucleic acid dye-enhanced electrochemical biosensor provided the advantages of simplicity, sensitivity, and specificity and is expected to be an alternative for Hg²⁺ detection in actual environmental samples.

State-of-the-art developments in carbon quantum dots (CQDs): Photo-catalysis, bio-imaging, and bio-sensing applications

Carbon quantum dots (CQDs), the intensifying nanostructured form of carbon material, have exhibited incredible impetus in several research fields such as bio-imaging, bio-sensing, drug delivery systems, optoelectronics, photovoltaics, and photocatalysis, thanks to their exceptional properties. The CQDs show extensive photonic and electronic properties, as well as their light-collecting, tunable photoluminescence, remarkable up-converted photoluminescence, and photo-induced transfer of electrons were widely studied. These properties have great advantages in a variety of visible-light-induced catalytic applications for the purpose of fully utilizing the energy from the solar spectrum. The major purpose of this review is to validate current improvements in the fabrication of CQDs, characteristics, and visible-light-induced catalytic applications, with a focus on CQDs multiple functions in photo-redox processes. We also examine the problems and future directions of CQD-based nanostructured materials in this growing research field, with an eye toward establishing a decisive role for CQDs in photocatalysis, bio-imaging, and bio-sensing applications that are enormously effective and stable over time. In the end, a look forward to future developments is presented, with a view to overcoming challenges and encouraging further research into this promising field.

Biomarker based biosensors: An opportunity for diagnosis of COVID-19

Early diagnosis and treatment of diseases are crucial research areas of human health. For early diagnosis, one method that has proven efficient is the detection of biomarkers which can provide real-time and accurate biological information. Most biomarker detection is currently carried out at localised dedicated laboratories using large and automated analysers, increasing waiting time and costs. Smaller, faster, and cheaper devices could potentially replace these time-consuming laboratory analyses and make analytical results available as point-of-care diagnostics. Innovative biosensor-based strategies could allow biomarkers to be tested reliably in a decentralised setting. Early diagnosis of COVID-19 patients has a key role in order to use quarantine and treatment strategies in a timely manner. Raised levels of several biomarkers in COVID-19 patients are associated with respiratory infections or dysfunction of various organs. Through clinical studies of COVID-19 patient biomarkers such as ferritin, Interleukins, albumin and …are found to reveals significant differences in their excretion ranges from healthy patients and patients with SARS-CoV-2, in addition to the development of biomarkers based biosensor such as stated biomarkers can be used and to investigate more specific biomarkers further proteomic analysis can be performed. This review presents several biomarker alterations in COVID-19 patients such as salivary, circulatory, coagulation, cardiovascular, renal, liver, C-reactive protein (CRP), immunological and inflammatory biomarkers. Also, biomarker sensors based on electrochemical, optical, and lateral flow characteristics which have potential applications for SARS-COV-2 in the recent COVID-19 pandemic, will be discussed.

Fabrication of Au/Fe3O4/RGO based aptasensor for measurement of miRNA-128, a biomarker for acute lymphoblastic leukemia (ALL)

Due to their high sensitivity, simplicity, portability, self-contained, and low cost, the development of electrochemical biosensors is a beneficial way to diagnose and anticipate many types of cancers. An electrochemical nanocomposite-based aptasensor is fabricated for the determination of miRNA-128 concentration as the acute lymphoblastic leukemia (ALL) biomarker for the first time. The aptamer chains were immobilized on the surface of the glassy carbon electrode (GCE) through gold nanoparticles/magnetite/reduced graphene oxide (AuNPs/Fe3O4/RGO). Fast Fourier transform infrared (FTIR), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), and transmission electron microscopy (TEM) were used to characterize synthesized nanomaterials. Cyclic voltammetry (CV), square wave voltammetry (SWV), and electrochemical impedance spectroscopy (EIS) were used to characterize the modified GCE in both label-free and labeled methods. The results indicate that the modified working electrode has high selectivity and for miRNA-128 over other biomolecules. The hexacyanoferrate redox system typically operated at around 0.3 V (vs. Ag/AgCl), and the methylene blue redox system ran at about 0 V, were used as an electrochemical probe. The detection limit and linear detection range for hexacyanoferrate and methylene blue are 0.05346 fM, 0.1-0.9 fM, and 0.005483 fM, 0.01-0.09 fM, respectively. The stability and diffusion control analyses were performed as well. In both label-free and labeled methods, the modified electron showed high selectivity for miRNA-128. The use of methylene blue as a safer redox mediator caused miRNA-128 to be detected with greater accuracy at low potentials in PBS media. The findings also show the substantial improvement in detection limit and linearity by using reduced graphene oxide-magnetite-gold nanoparticles that can be verified by comparing with previous studies on the detection of other miRNAs.

Enhancing hydrogen peroxide activation of CuCo layered double hydroxide by compositing with biochar: Performance and mechanism

In this study, CuCo layered double hydroxide/biochar composite (CuCo LDH/BC) was prepared and employed for activating H₂O₂ to degrade ciprofloxacin (CIP), a common fluroquinolone antibiotic detected in water environment. The as-synthesized catalysts were also comprehensively characterized to study the physiochemical properties. For the catalytic activity, the degradation rate of CuCo LDH/BC to CIP was approximately 1.5 times higher than that of CuCo LDH. The improved catalytic activity can be ascribed to the synergistic effect between CuCo LDH and BC, such as more functional groups, accelerated electron transfer, and varied charge distribution. Meanwhile, CuCo LDH/BC/H₂O₂ could degrade CIP efficiently in a wider pH range comparing with CuCo LDH/H₂O₂, and the efficiency was approximately 84.7% at neutral pH within 90 min. The generation of OH, O₂^- and ¹O₂ in CuCo LDH/BC/H₂O₂ system were then verified by electron spin resonance (ESR) technology. The quenching experiments indicated that both non-radical pathway (¹O₂) and radical pathway (OH, O₂^-) led to CIP degradation, in which O₂^- and ¹O₂ made major contribution. Then, the intermediate products of CIP during catalytic reaction were monitored by high-performance liquid chromatography-mass spectrometry (HPLC-MS), and the environmental risk of these degradation intermediates was tested through seed germination experiments. This study tends to provide valuable information for LDH/BC application in heterogeneous Fenton-like reaction.

Electric Field-Induced Specific Preconcentration to Enhance DNA-Based Electrochemical Sensing of Hg2+ via the Synergy of Enrichment and Self-Cleaning

Efficient preconcentration is critical for sensitive and selective electrochemical detection of metal ions, but rapid specific enrichment with depressed absorption of interfering ions at the electrode is challenging. Here, we proposed an electric field-induced specific preconcentration to boost the analytical performance of DNA-based electrochemical sensors for Hg²⁺ detection. As for such preconcentration, a positive external electric field was first used to enrich Hg²⁺ at an electrode assembled with T-rich DNA, thus boosting T-Hg²⁺-T recognitions. The following applied inverse electric field strips the nonspecifically absorbed Hg²⁺ and other interfering ions, thus depressing matrix interferences via self-cleaning. Based on this principle, we designed a portable device to realize programmable control of electric fields; a T-Hg²⁺-T recognition-based electrochemical sensor was thus fabricated as a model platform to assess the feasibility of electric field-induced preconcentration. The experimental results revealed that such a strategy decreased the time of T-Hg²⁺-T-based recognition from 60 to 20 min and led to detection with better reproducibility by depressing the influence of free Hg²⁺ as well as interfering ions. This strategy offered Hg²⁺ detection limits of 0.01 pM─three-fold better than that without preconcentration─within 22 min. The proposed preconcentration strategy offers a new way to enhance the analytical performance of sensing at the solid-liquid interface.

A novel method based on Ag-Au nanorings with tunable plasmonic properties for the sensitive detection of amantadine

To prevent the toxic effect of amantadine (AMD) on humans, a sensitive and direct detection method is required. The conventional enzyme-linked immunosorbent assay (ELISA) usually shows a monochromatic gradient color variation with the concentration of the target; hence, it is not a sensitive method for naked-eye detection. In this work, Ag-Au nanorings with highly tunable plasmon properties were synthesized as colorimetric nanosensors. The growth of Ag on the hollow nanorings led to rich color variations. Ag-Au nanorings were integrated into ELISA for the sensitive detection of AMD with the naked eye. The proposed method showed high sensitivity for the qualitative and quantitative detection of AMD, the visible cut-off value (0.2 ng mL^-1) and limit of detection (0.071 ng mL^-1) were 10-fold and 4.7-fold lower, respectively, than those of conventional ELISA. This method showed a linear range of 0.08-2 ng mL^-1 and 4-12 ng mL^-1. The detection results of this method on 100 samples (food samples and municipal water) agreed well with those of liquid chromatography-tandem mass spectrometry. The proposed plasmonic ELISA has high sensitivity, easy operation, and naked-eye readout.

Novel Carboxylic Acid-Capped Silver Nanoparticles as Antimicrobial and Colorimetric Sensing Agents

The present work reports the synthesis, characterization, and antimicrobial activities of adipic acid-capped silver nanoparticles (AgNPs@AA) and their utilization for selective detection of Hg2+ ions in an aqueous solution. The AgNPs were synthesized by the reduction of Ag+ ions with NaBH4 followed by capping with adipic acid. Characterization of as-synthesized AgNPs@AA was carried out by different techniques, including UV-Visible spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Dynamic Light Scattering (DLS), and zeta potential (ZP). In the UV-Vis absorption spectrum, the characteristic absorption band for AgNPs was observed at 404 nm. The hydrodynamic size of as-synthesized AgNPs was found to be 30 ± 5.0 nm. ZP values (-35.5 ± 2.4 mV) showed that NPs possessed a negative charge due to carboxylate ions and were electrostatically stabilized. The AgNPs show potential antimicrobial activity against clinically isolated pathogens. These AgNPs were found to be selectively interacting with Hg2+ in an aqueous solution at various concentrations. A calibration curve was constructed by plotting concentration as abscissa and absorbance ratio (AControl - AHg/AControl) as ordinate. The linear range and limit of detection (LOD) of Hg2+ were 0.6-1.6 μM and 0.12 μM, respectively. A rapid response time of 4 min was found for the detection of Hg2+ by the nano-probe. The effect of pH and temperature on the detection of Hg2+ was also investigated. The nano-probe was successfully applied for the detection of Hg2+ from tap and river water.

Tetrahedral DNA-directed core-satellite assembly as SERS sensor for mercury ions at the single-particle level

To monitor the deteriorating mercury emissions, it is imperative to propose methods for detecting mercury ions (Hg²⁺) with sensitivity and selectivity. The SERS spectral-resolved single-particle detection approach can be carried out using dark-field optical microscopy (DFM) combined with Raman spectroscopy. Herein, we have designed a novel yet convenient single-particle detection assay for quantifying Hg²⁺ using DFM-correlated Raman spectroscopy. In the assay, a tetrahedral DNA-directed core-satellite nanostructure is used as the SERS probe. Especially, one edge of the tetrahedron is made up of a single-stranded DNA containing a Hg²⁺ aptamer, which reconfigures upon the specific recognition of Hg²⁺. As a result, the interparticle distance reduces from 4.5 to 1.2 nm, thus generating Raman signal enhancement. As a proof of concept, Hg²⁺ was detected in a linear range from 1 to 100 nM based on the variation in SERS intensity. Furthermore, the experimental results were supported by the finite difference time domain (FDTD) calculations. Owing to its high sensitivity and selectivity, this method was further employed to detect Hg²⁺ in practical tap water and lake water samples, revealing that the single-particle detection strategy holds great promise for Hg²⁺ analysis in real environment analysis.

Rapid electrochemical quantification of trace Hg2+ using a hairpin DNA probe and quantum dot modified screen-printed gold electrodes

Rapid, simple, sensitive and specific approaches for mercury(ii) (Hg²⁺) detection are essential for toxicology assessment, environmental protection, food analysis and human health. In this study, a ratiometric hairpin DNA probe based electrochemical biosensor, which relies on hairpin DNA probes conjugated with water-soluble and carboxyl functionalized quaternary Zn–Ag–In–S quantum dot (QD) on screen-printed gold electrodes (SPGE), referred to as the HP-QDs-SPGE electrochemical biosensor in this study, was developed for Hg²⁺ detection. Based on the “turn-off” reaction of a hairpin DNA probe binding with a mismatched target and Hg²⁺ through the formation of T–Hg²⁺–T coordination, the HP-QDs-SPGE electrochemical biosensor can rapidly quantify trace Hg²⁺ with high ultrasensitivity, specificity, repeatability and reproducibility. The conformational change of the hairpin DNA probe caused a significant decrease in electrochemical intensity, which could be used for the quantification of Hg²⁺. The linear dynamic range and high sensitivity of the HP-QDs-SPGE electrochemical biosensor for the detection of Hg²⁺ was studied in vitro, with a broad linear dynamic range of 10 pM to 1 μM and detection limits of 0.11 pM. In particular, this HP-QDs-SPGE electrochemical biosensor showed excellent selectivity toward Hg²⁺ ions in the presence of other metal ions. More importantly, this biosensor has been successfully used to detect Hg²⁺ in deionized water, tap water, groundwater and urine samples with good recovery rate and small relative standard deviations. In summary, the developed HP-QDs-SPGE electrochemical biosensor exhibited promising potential for further applications in on-site analysis.

A ratiometric hairpin DNA probe based electrochemical biosensor, which relies on hairpin DNA probes conjugated with water-soluble and carboxyl functionalized quantum dot on screen-printed gold electrodes, was developed for Hg²⁺ detection.

Recent Trends and Future Perspectives of Emergent Analytical Techniques for Mercury Sensing in Aquatic Environments

Environmental emissions of mercury from industrial waste and natural sources, even in trace amounts, are toxic to organisms and ecosystems. However, industrial-scale mercury detection is limited by the high cost, low sensitivity/specificity, and poor selectivity of the available analytical tools. This review summarizes the key sensors for mercury detection in aqueous environments: colorimetric-, electrochemical-, fluorescence-, and surface-enhanced Raman spectroscopy-based sensors reported between 2014-2021. It then compares the performances of these sensors in the determination of inorganic mercury (Hg²⁺ ) and methyl mercury (CH₃ Hg⁺ ) species in aqueous samples. Mercury sensors for aquatic applications still face serious challenges in terms of difficult deployment in remote areas and low robustness, reliability, and selectivity in harsh environments. We provide future perspectives on the selective detection of organomercury species, which are especially toxic and reactive in aquatic environments. This review is intended as a valuable resource for scientists in the field of mercury sensing.

Achieving Ultrasensitive Point-of-Care Assay for Mercury Ions with a Triple-Mode Strategy Based on the Mercury-Triggered Dual-Enzyme Mimetic Activities of Au/WO3 Hierarchical Hollow Nanoflowers

The exploration of new strategies for portable detection of mercury ions with high sensitivity and selectivity is of great value for biochemical and environmental analyses. Herein, a straightforward, convenient, label-free, and portable sensing platform based on a Au nanoparticle (NP)-decorated WO₃ hollow nanoflower was constructed for the sensitive and selective detection of Hg(II) with a pressure, temperature, and colorimetric triple-signal readout. The resulting Au/WO₃ hollow nanoflowers (Au/WO₃ HNFs) could efficaciously impede the aggregation of Au NPs, thus significantly improving their catalytic activity and stability. The sensing mechanism of this new strategy using pressure as a signal readout was based on the mercury-triggered catalase mimetic activity of Au/WO₃ HNFs. In the presence of the model analyte Hg(II), H₂O₂ in the detection system was decomposed to O₂ fleetly, resulting in a detectable pressure signal. Accordingly, the quantification of Hg(II) was facilely realized based on the pressure changes, and the detection limit could reach as low as 0.224 nM. In addition, colorimetric and photothermal detection of Hg(II) using the Au/WO₃ HNFs based on their mercury-stimulated peroxidase mimetic activity was also investigated, and the detection limits were calculated to be 78 nM and 0.22 μM for colorimetric and photothermal methods, respectively. Hence, this nanosensor can even achieve multimode determination of Hg(II) with the concept of point-of-care testing (POCT). Furthermore, the proposed multimode sensing platform also displayed satisfactory sensing performance for the Hg(II) assay in actual water samples. This promising strategy may provide novel insights on the fabrication of a multimode POCT platform for sensitive, selective, and accurate detection of heavy metal ions.

Activation of persulfate by swine bone derived biochar: Insight into the specific role of different active sites and the toxicity of acetaminophen degradation pathways

Recently, persulfate (PS) activation system has grown up as a primary branch of advanced oxidation processes, and biochar has been recognized as a potential nonmetal material in this field. However, few studies have focused on the corresponding relationship between actives sites on biochar and active species in AOPs. To pave this way, similar biochar (obtained from different pyrolysis temperature) with different functional structures were involved. In this study, biochar derived from swine bone (BBC) was applied in PS activation system to degrade acetaminophen (ACT). The results showed that both radical and non-radical pathway worked in the PS/BBCs systems, and the degradation rate (from 0.1042 to 0.4364 min^-1) climbed with the increase of pyrolysis temperature (from 700 to 900 °C). To probe into the corresponding relationship between functional structure and active species, the effect of pyrolysis temperature on functional structure was analyzed. It came out that 1) defects could act as active sites for various active species; 2) persistent free radicals could do favor to the generation of ¹O₂ and O₂^-; 3) hydroxyapatite in swine bone only served as hard templet for the porous structure. ACT degradation process was measured by Liquid chromatograph-mass spectrometer, and Scendesmus obliquus was applied to investigate the toxicity of PS/BBCs system. It illustrated that the existence of SO₄^- mainly contributed to the generation of high toxic intermediates (such as biphenyl and diphenyl ether) in the PS/BBCs system. Furthermore, the enhancement of adsorption capacity would mitigate the toxicity of PS/BBCs systems to some extent.

Rapid and sensitive detection of Hg2+ with a SERS-enhanced lateral flow strip

A SERS-LFS strategy was designed and applied for the direct detection of target Hg2+ with greatly improved sensing performance by SERS measurements on the T line of the LFS, which did not change the intrinsic simplicity of the LFS.

Mimetic peroxidase based on a gold amalgam for the colorimetric sensing of trace mercury(ii) in water samples

A simple and effective AuNPs/H-rGO/CC colorimetric sensing interface was constructed for the sensitive, selective, and facile determination of Hg2+ in water samples.

Biothiol-Functionalized Cuprous Oxide Sensor for Dual-Mode Sensitive Hg2+ Detection

Hg²⁺ ions are one of the highly poisonous heavy metal ions in the environment, so it is urgent to develop rapid and sensitive detection platforms for detecting Hg²⁺ ions. In this work, a novel electrochemical and photoelectrochemical dual-mode sensor (l-Cys-Cu₂O) was successfully fabricated, and the sensor exhibits a satisfactory detection limit (0.2 and 0.01 nM) for the detection of Hg²⁺, which is far below the dangerous limit of the U.S. Environmental Protection Agency. The linear ranges of dual-mode Hg²⁺ detections were 0.33-3.3 and 0.17-1.33 μM, respectively. Moreover, the sensor shows desirable stability, selectivity, and reproducibility for detecting Hg²⁺ ions. For river water samples, the recoveries of 96.6-101.4% (electrochemical data) and 93.0-105.6% (photoelectrochemical data) were obtained, indicating that the sensor could be successfully applied in the determination of Hg²⁺ ions in environmental water. Therefore, the designed sensor has a potential in the trace-level detection of Hg²⁺ ions.

Detection of hazardous mercury ion using [5]helicene-based fluorescence probe with "TurnON" sensing response for practical applications

A new fluorescence probe based on [5]helicene derivative (MT) was designed and synthesized. The chemical structure of the probe was fully characterized by NMR, mass spectrometry and X-ray crystallography. MT which is the combination of thioamide[5]helicene with Schiff base-thiophene moiety, exhibited a high selectivity to detect Hg²⁺ through irreversible desulfurization reaction with "TurnON" fluorescence response and large Stokes shift of 110 nm in aqueous methanol solution. The detection limit of MT was 1.2 ppb (6.0 × 10^-3 µM), which is lower than the limit of Hg²⁺ level in drinking water, as specified by WHO (6.0 ppb) and U.S. EPA (2.0 ppb). The Hg²⁺ detection range of the probe was 0.07-1.6 µM with good linearity. Under UV irradiation, MT possessed the capability to detect Hg²⁺ in diverse context of real samples, including drinking and sea waters, vegetable tissue and brain tumor cell. In addition, MT could be used as a paper test strip for monitoring and screening of Hg²⁺ contamination in environment.

Wide-field determination of aqueous mercury(II) based on tail-extensible DNA fluorescent probe with tunable dynamic range

Mercury (Hg) is one of the most hazardous pollutants, widely distributed in water, atmosphere, and soil, while the Hg contents from different sources are greatly different. Until now, numerous reported methods are only suitable for a kind of sample because they cannot reconcile sensitivity and linear range. In this work, a tail-extensible DNA fluorescent probe for "turn on" detection of Hg²⁺ with tunable dynamic range and high sensitivity was developed, which was based on segmental hybridization between silver nanoclusters (AgNCs)-covered DNA and different guanine-rich DNAs. By adding adenine-guanine-cytosine (AGC) base repeats as a tail of the guanine-rich DNA, the formation constant of T-Hg²⁺-T complex was effectively modulated within two orders of magnitude. Based on it, a tunable dynamic range from 0.035 to 0.2 pM to 8.0-120.0 pM was achieved by combining four fluorescent probes with different tail lengths. The Hg²⁺contents from different sources were successfully measured. This evidenced the proposed sensor's application toward wide-field detection, which is useful for the direct and objective comparison of results from different sources, and therefore providing a way for solving the shortcomings of reported methods for Hg²⁺ detection. Additionally,this present method is simple, cost-effective and time-saving, ultrasensitive and highly selective, which is favorable for expanding its applications and subsequent mercury pollution control.

Gold nanoparticles-modified MnFe2O4 with synergistic catalysis for photo-Fenton degradation of tetracycline under neutral pH

To decrease the adverse environmental and health-related effects of antibiotics, a series of MnFe₂O₄-Au (MFO-Au) composites were prepared by simple co-precipitation and photoreduction methods for efficient photo-Fenton degradation of tetracycline (TC). The synergistic effect of MFO and gold nanoparticles (AuNPs) with high absorption of visible light and strong photogenerated carrier separation efficiency endowed MFO-Au₃ an outstanding photo-Fenton catalytic performance for TC degradation in neutral condition. The surface hydroxyl of MFO profited to generation of •OH, and negative charged or partially polarized AuNPs benefited to adsorption of H₂O₂, which had a synergistic effect on enhancing the photo-Fenton catalytic performance of MFO-Au. 88.3% of TC was efficiently removed and about 51.9% of TOC decreased within 90 min. The electron spin resonance and quenching tests suggested that h⁺ and e^- were responsible for the high catalytic degradation and •OH and •O₂^- participated in the photo-Fenton reaction. The toxicity assessment by seed germination experiments showed efficient toxicity reduction of this system. Besides, MFO-Au exhibited high stability, good cycle, relatively economical and practical application performance, which is expected to provide potential guidance for the design and combination of noble nanoparticles with high stability and spinel bimetallic oxides with high catalytic activity in photo-Fenton reactions.

Boron nitride nanosheet modified label-free electrochemical immunosensor for cancer antigen 125 detection

In this presented study, a new boron nitride nanosheets modified label-free electrochemical immunosensors were prepared for early detection of cancer antigen 125 (CA125). To aim for, boron nitride (BN) nanosheets were synthesized by conventional sonication-assisted method and then characterized. BN nanosheets were used for the surface modification of the working electrode of the screen-printed electrode (SPE). Anti CA125 antibody was then directly immobilized onto the electrode surface due to its natural affinity towards BN nanosheets. Modified electrodes were blocked with BSA and finally protected with Nafion. The newly synthesized label-free immunosensor demonstrated good detection properties to CA125 with a linear range of 5-100 U and a detection limit of 1.18 U/mL. The developed immunosensor also showed excellent reproducibility, selectivity, and stability profiles. Additionally, this immunosensor was successfully used for the detection of CA125 in artificial human serum samples along with the interfering agents. Also, it is expected that the prepared immunosensor should carry the good potential for point-of-care diagnosis in real cases.

Facile one-pot synthesis of carbon self-doped graphitic carbon nitride loaded with ultra-low ceric dioxide for high-efficiency environmental photocatalysis: Organic pollutants degradation and hexavalent chromium reduction

In the present study, an innovative carbon self-doped g-C₃N₄ (CCN) loaded with ultra-low CeO₂ (0.067-0.74 wt%) composite photocatalyst is successfully synthesized via a facile one-pot hydrothermal and calcination method. The CeO₂/CCN exhibits superior photocatalytic performance for tetracycline degradation (78.9% within 60 min), H₂O₂ production (151.92 μmol L^-1 within 60 min), and Cr(VI) reduction (99.5% within 40 min), which much higher than that of g-C₃N₄, CCN, CeO₂, and CeO₂/g-C₃N₄. The enhanced photocatalytic performance is originated from the fact that the doping of C can efficaciously broaden the utilization range of solar light and improve the reduction ability of photogenerated electrons. Meanwhile, the ultra-low loading of CeO₂ can effectually promote the migration of photogenerated electrons and enhance the specific surface area. Besides, the experiments of pH effect and cycle ability indicate that CeO₂/CCN has excellent durability and stability. Finally, the photocatalytic mechanism of CeO₂/CCN is systematically discussed. This work proves that combining element doping and semiconductor coupling is a promising strategy to design high-efficiency g-C₃N₄-based photocatalysts.

An ultrasensitive disposable sandwich-configuration electrochemical immunosensor based on OMC@AuNPs composites and AuPt-MB for alpha-fetoprotein detection

Early finding and diagnosis are critical for prevention and treatment of hepatocellular carcinoma (HCC). Alpha-fetoprotein (AFP) is a typical biomarker of HCC. Since AFP level can reflect the severity of HCC, it is essential to ensure the accurate detection of AFP. In this study, through a combination of the advantages exhibited by ordered mesoporous carbon (OMC)@gold nanoparticles (AuNPs) composites and AuPt-methylene blue (AuPt-MB), a disposable ultrasensitive sandwich-configuration electrochemical immunosensor for determination of AFP was designed. Characterized by excellent conductivity, highly ordered pore distribution and great surface area, OMC can be effective in promoting electron transfer and loading a large number of AuNPs. In the meantime, AuNPs can also immobilize AFP-Ab₁ through Au-N bonds. As a new redox-active species, rod-like AuPt-MB demonstrates high conductivity, uniform morphology and excellent biocompatibility, which makes it capable not only to fix AFP-Ab₂, but also to release electrochemical signals. A wide linearity of 10 fg mL^-1-100 ng mL^-1 and a low detection limit of 3.33 fg mL^-1 (S/N = 3) were obtained. Moreover, the proposed immunosensor exhibited acceptable selectivity, high stability and reproducibility. The excellent performance in detecting serum samples endows the proposed immunosensor with broad prospects of extensive application in the detection of disease biomarkers.

Two birds with one stone: The detection of nerve agents and AChE activity with an ICT-ESIPT-based fluorescence sensor

Nerve agents are among the world's deadliest poisons, and the target enzyme is acetylcholinesterase (AChE). To better diagnosis nerve agent poisonings, a reliable diagnostic method for both nerve agents and AChE is desirable. Herein, we synthesized a series of fluorescent sensors for both real nerve agents and acetylcholinesterase activity detection. Among these sensors, HBQ-AE exhibited a fast response rate (within 10 s for nerve agent and 8 min for AChE), good sensitivity (the limit of detection is 6 nM and 0.2 U/mL) and a high off/on contrast. To the best of our knowledge, HBQ-AE is the first fluorescence sensor for nerve agents and AChE activity detection. The fluorescent change of HBQ-AE from nonfluorescence to blue fluorescence (nerve agent) or orange fluorescence (AChE) by excitation at 365 nm can be easily observed with the naked eye. HBQ-AE was successfully applied to image nerve agents and AChE activity in living cells. Moreover, HBQ-AE is the vital member to construct a test paper that can be employed to detect and diagnose chemical warfare agents.

Fabrication of porous carbon derived from cotton/polyester waste mixed with oyster shells: Pore-forming process and application for tetracycline removal

Porous carbon was fabricated from cotton/polyester-based textile wastes as a carbon source coupled with oyster shells for tetracycline removal. The preparation conditions were optimized and detailed characterization was conducted to study the effects of oyster shells on cotton/polyester pyrolysis. The optimal pyrolysis temperature (900 °C), pyrolysis time (1 h) and mass ratio (OS/CPW of 1:1) were determined using the Box-Behnken experiment. The best porous carbon reached a surface area of 645.05 m²/g. Oyster shells acted as templates to produce cotton/polyester-based porous carbon and a possible pore-forming process was proposed. CaO was converted from CaCO₃, which played the dominant role in developing the mesoporous structure. CO₂ gas released from CaCO₃ promoted the creation of micropore structure. In addition, the impurites of oyster shells acted as the dispersing agent inhibiting CaCO₃ and CaO aggregation and growth. Fe₂O₃ and K₂O from impurities reacted with the carbon skeleton to increase microporosity. Finally, the well-developed and uniform porous carbon was obtained. The first-pseudo order model and Langmuir isotherms were suitable. The maximum adsorption capacity of PC-OS-900 was 515.17 mg/g which competed with other waste-based adsorbents. The TET adsorption mechanism was related to pore distribution, hydrogen bonds, π-π EDA interactions and electrostatic interactions.

Colorimetric detection of Hg(II) by γ-aminobutyric acid-silver nanoparticles in water and the assessment of antibacterial activities

In this work, we report the synthesis of silver nanoparticles (AgNPs) via a wet-chemical reduction procedure using citrate (Cit) and γ-aminobutyric acid (GABA) as stabilizers. The formation of GABA-Cit@AgNPs was confirmed by UV-vis spectroscopy with a surface plasmon resonance band at 393 nm clearly confirming the formation of silver nanoparticles. AgNPs were characterized using UV-vis spectroscopy, attenuated total reflectance-fourier transform infrared spectroscopy (ATR-FTIR), transmission electron microscope (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), dynamic light scattering (DLS), and zeta potential. The as-prepared AgNPs can be used for the detection of hazardous mercury ions (Hg²⁺) in water by colorimetric method with a limit of detection (LOD) and limit of quantitation (LOQ) of 2.37 μM and 3.99 μM, respectively. The linear working range for Hg²⁺ detection is 5-35 μM and the sensor probe was applied to investigate Hg²⁺ in real drinking water samples with satisfied results. Rapid response to Hg²⁺ is also observed when the nanoparticles are composited within hydrogels. Moreover, GABA-Cit@AgNPs shows antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The fast and sensitive response of the proposed Hg²⁺ sensor, together with its antibacterial activities, makes GABA-Cit@AgNPs potentially applicable for the development of cheap, portable, colorimetric sensors in fieldwork.

A double signal amplification-based homogeneous electrochemical sensor built on catalytic hairpin assembly and bisferrocene markers

A facile, sensitive and unmodified Hg²⁺ homogeneous electrochemical sensor based on bisferrocene signal markers and catalytic hairpin self-assembly (CHA) was built on a gold disk electrode. Three hairpin probes were designed, in which thiol was labeled at both ends of the hairpin probe 1(HP1), while bisferrocene, a redox signal marker, was labeled at both ends of the hairpin probe 2(HP2) and hairpin probe 3(HP3). Due to the Hg²⁺ mediated thymine-Hg (II)-thymine (T-Hg²⁺-T) structure, when Hg²⁺ is introduced, the T-Hg²⁺-T that occurred between the probe DNA and helper DNA could open the hairpin structure of probe DNA and form a rigid DNA triangles structure by CHA. Simultaneously, four bisferrocene signal markers also reached the surface of the electrode and built potential-assisted Au-S self-assembly to achieve signal amplification. Under the optimized condition, the sensor can achieve good electrochemical response Hg²⁺detection, and the detection limit is as low as 0.6 pM. furthermore, this sensor has high selectivity for Hg²⁺ detection.

Cobalt metal-organic framework modified carbon cloth/paper hybrid electrochemical button-sensor for nonenzymatic glucose diagnostics

In the growing pandemic, family healthcare is widely concerned with the increase of medical self-diagnosis away from the hospital. A cobalt metal-organic framework modified carbon cloth/paper (Co-MOF/CC/Paper) hybrid button-sensor was developed as a portable, robust, and user-friendly electrochemical analytical chip for nonenzymatic quantitative detection of glucose. Highly integrated electrochemical analytical chip was successfully fabricated with a flexible Co-MOF/CC sensing interface, effectively increasing the specific area and catalytic sites than the traditional plane electrode. Based on the button-sensor, rapid quantitative detection of glucose was achieved in multiple complex bio-matrixes, such as serum, urine, and saliva, with desired selectivity, stability, and durability. With the advantages of low cost, high environment tolerance, ease of production, our nanozyme-based electrochemical analytical chip achieved reliable nonenzymatic electrocatalysis, has great potential for the application of rapid on-site analysis in personalized diagnostic and disease prevention.

Transcription profiling-guided remodeling of sulfur metabolism in synthetic bacteria for efficiently capturing heavy metals

Heavy metal contamination is becoming a global problem threatening human health. Heavy metal removal by engineered microbes by cellular adsorption and uptake is a promising strategy for treatment of heavy metal contamination. However, this strategy is confronted with limited heavy metal-capturing elements. In this study, we performed a transcription profiling-guided strategy for construction of heavy metal-capturing synthetic bacteria. Transcription profiling of a heavy metal-tolerating Cupriavidus taiwanensis strain revealed up-regulation of sulfur metabolism-related operons (e.g., iscSAU and moaEDAB) by Pb²⁺ and Cd²⁺. A synthetic Escherichia coli strain, EcSSMO, was constructed by design of a synthetic sulfur metabolism operon (SSMO) based on iscSAU/moaEDAB. Biochemical analysis and X-ray photoelectron spectroscopy (XPS) revealed that the synthetic bacteria had remodeled sulfur metabolism and enhanced heavy metal-tolerating capacity, with higher surviving EcSSMO cells than the surviving control cells Ec0 (not containing SSMO) at 50 mg/L of Pb²⁺ and Cd²⁺ (>92 % versus <10 %). Moreover, EcSSMO exhibited much higher heavy metal-capturing capacity than Ec0, removing>90 % of Pb²⁺ and Cd²⁺ at 5 mg/L of Pb²⁺ and Cd²⁺, and >40 % of both heavy metals even at 50 mg/L of Pb²⁺ and Cd²⁺. This study reveals emphasizes feasibility of transcription profiling-guided construction of synthetic organisms by large-scale remodeling metabolic network.

From Small Molecules Toward Whole Cells Detection: Application of Electrochemical Aptasensors in Modern Medical Diagnostics

This paper focuses on the current state of art as well as on future trends in electrochemical aptasensors application in medical diagnostics. The origin of aptamers is presented along with the description of the process known as SELEX. This is followed by the description of the broad spectrum of aptamer-based sensors for the electrochemical detection of various diagnostically relevant analytes, including metal cations, abused drugs, neurotransmitters, cancer, cardiac and coagulation biomarkers, circulating tumor cells, and viruses. We described also possible future perspectives of aptasensors development. This concerns (i) the approaches to lowering the detection limit and improvement of the electrochemical aptasensors selectivity by application of the hybrid aptamer-antibody receptor layers and/or nanomaterials; and (ii) electrochemical aptasensors integration with more advanced microfluidic devices as user-friendly medical instruments for medical diagnostic of the future.

Reusable, facile, and rapid aptasensor capable of online determination of trace mercury

Herein, we reported a homemade waveguide-based evanescent wave aptasensor for the facile online monitoring of mercury pollution. The aptasensor exploited the high selectivity of hairpin structure-based thymidine-Hg²⁺-thymidine coordination chemistry (T-T mismatch) for Hg²⁺ recognition and the stably regenerable capability of DNA-functionalized waveguide surfaces. The presence of Hg²⁺ caused the T-T mismatch of Cy5.5-labeled T-rich single-stranded DNA sequences. The formed hairpin structures blocked the further hybridization of T-rich single-stranded DNA sequences with the complementary DNA strands that are modified on the waveguide surface; this phenomenon was accompanied by the decrease in the fluorescent signals excited by the evanescent wave. The limit of detection in real water samples was determined to be 0.2 μg/L, which was comparable with that of 0.4 μg/L in an ultrapure water under controlled conditions. And the linear range was observed from 1.4 µg/L to 240.7 µg/L. The negligible environmental matrix effect on the performance ensured the reliability of the proposed aptasensor. Moreover, the cross reactivity of this method toward other investigated metal ions was negligible. Through the delicate surface modification with DNA molecules covalently, the chip was reused at least 31 times with a relative standard deviation (RSD) of less than 19%. A Hg²⁺ pollution accident was successfully detected within 30 min, shedding new light in pollution monitoring, environment restoration, and emergency treatment.