Detection Of Acetamiprid Research Articles

Visual aptasensor based on PtNPs/g-C3N4 and DNase I for the field detection of acetamiprid.

A visual aptasensor based on the combination of graphitic carbon nitride loaded with platinum nanoparticles (PtNPs/g-C3N4) and deoxyribonuclease I (DNase I) was developed for detecting acetamiprid. The prepared PtNPs/g-C3N4 exhibited excellent peroxidase (POD)-like activity, demonstrating the capacity to oxidize the colourless o-phenylenediamine (OPD) to produce the coloured product diaminophenazine (DAP) in the presence of hydrogen peroxide (H2O2). The DNA aptamer of acetamiprid can adsorb onto the surface of PtNPs/g-C3N4, thereby inhibiting its POD activity. The binding of acetamiprid to its aptamer results in the aptamer desorbing from the surface of PtNPs/g-C3N4 and subsequent digestion by DNase I. Ascribed to the synergistic effect of these factors, the aptasensor can achieve the rapid on-site detection of acetamiprid based on the acetamiprid-induced the colour change of the solution just with the smartphone. Furthermore, due to the remarkable fluorescence signal of DAP at 570nm, the aptasensor under fluorescence mode enables highly sensitive and quantitative detection of acetamiprid with a linear range of 1 ng/mL to 4µg/mL and a detection limit as low as 0.31 ng/mL.Theaptasensor has successfully realized the detection of acetamiprid in river water and cucumber samples, offering a novel perspective for the rapid assessment of environmental pollution and food safety risks associated with acetamiprid residues.

Dual signal amplification strategy-based electrochemical aptasensor utilizing redox molecule/MOF composites for multi-pesticide detection

Electrochemical aptasensor is a great tool for simultaneously assessing harmful pesticide residues in agricultural products and foods. This study ingeniously designed an electrochemical aptasensor based on dual signal amplification strategies for concurrent detection of various pesticide residues. Firstly, poly(diallyldimethylammonium chloride)-functionalized reduced graphene oxide (PR) and Au-Pt-Pd trimetallic nanoflowers supported on HP-UiO66-NH2 were creatively employed together as substrates to load more aptamers, ascribed to the improved conductivity, abundant sites and a large electrochemical effective surface area. Secondly, ferrocene-cysteine gold nanoparticles supported on CeMOF(Ⅲ, Ⅳ) and methylene blue-loaded MOF235 were innovatively engineered to build two distinctive signal labels, which displayed comparable large and stable signal currents among other redox molecule/MOF composites. Additionally, PR contributed further signal amplification. Consequently, the constructed aptasensor showed superior performance for simultaneous detection of acetamiprid (AD) and malathion (ML), with linear ranges from 10 pM to 0.1 μM and detection limits of 4.8 pM for AD and 0.51 pM for ML. Moreover, the aptasensor performed well in the assay of AD and ML in Chinese cabbage samples with high accuracy compared with a high-performance liquid chromatography-tandem mass spectrometry method. Overall, the strategies proposed herein provided a useful and potential route for general development of electrochemical aptasensors to simultaneously detect multiple pesticide residues.

One-step cascade amplification system based on entropy-driven catalysis and DNAzyme triggered DNA walker for label-free detection of acetamiprid

Herein, an electrochemical aptasensor for highly sensitive detection of acetamiprid (ACE) was constructed based on a one-step cascade amplification strategy. This innovative strategy integrated DNA walker containing DNAzyme sequence into entropy-driven catalysis (EDC) system. The trigger strand was released by aptamer-specific binding to ACE, initiating the EDC amplification circuit and delivering DNA walker strands. The dangling DNA walker continuously bound and cleaved hairpin substrate to form G-quadruplex fragments with the assistance of Mg2+. The G-quadruplex fragments folded and captured hemin to form multitudinous G-quadruplex/hemin complexes in the presence of K+, generating significantly enhanced current, enabling enzyme-free, label-free and highly sensitive detection of ACE, with a linear detection range of 100 fM to 50 nM and a detection limit of 68.36 fM (S/N = 3). The constructed aptasensor achieved the reliable detection of ACE in vegetable soil and cucumber samples, demonstrating its potential application prospects in environmental protection and food supervision.

Novel electrochemiluminescence platform utilizing AuNPs@Uio-66-NH2 bridged luminescent substrates and aptamers for the detection of pesticide residues in Chinese herbal medicines

A large number of Chinese herbal medicines (CHMs) are included in daily recipes, but their pesticide residues have aroused more and more concerns. In this paper, an electrochemiluminescence aptasensor was constructed for the trace detection of acetamiprid (ACE) in Angelica sinensis and Lycium barbarum. Possessing a large specific surface area, UiO-66 was modified with amino groups to improve biocompatibility, and the addition of AuNPs allowed UiO-66-NH2 to catalyze the formation of excited states of luminescent molecules (TPrA⁎; Ru(bpy)32+⁎), and AuNPs@UiO-66-NH2 was used to bridge the aptamer (Au–S) and luminescent substrate (peptide bond). The conventional luminescent reagent Ru(bpy)32+ was doped with multi-walled carbon nanotubes (MWCNTs) to obtain a more powerful and stable light signal. After optimizing the experimental parameters, the aptasensor could give results in 10 min with a detection range from 1×10−2-1×104 nM and a lower limit of detection (LOD) of 0.8 pM. The LOD of the study was at least one order of magnitude lower than that of the fluorescence detection method. Furthermore, the accuracy of the aptasensor was validated for spiked recovery experiments.

Signal amplification strategy based on target-controlled release of mediator for ultrasensitive self-powered biosensing of acetamiprid

Self-powered biosensors with high sensitivity have garnered significant interest for their potential applications in the realm of portable sensing. Herein, a self-powered biosensor with a novel signal amplification strategy was developed by integrating target-controlled release of mediator with an enzyme biofuel cell for the ultrasensitive detection of acetamiprid (ACE). Zeolitic imidazolate framework-67 was utilized as both a nanocontainer for capturing the electron mediator 2,2′-azidobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and a precursor for the synthesis of cobalt nanoparticles/nitrogen, sulfur-codoped carbon nanotubes (Co NPs/NS-CNTs), which were employed as the electrode material for constructing both the glucose oxidase-based bioanode and the laccase-based biocathode. The target analyte ACE can specifically bind to its aptamer, leading to the release of ABTS, which cyclically participates in the catalytic reaction of the biocathode, thereby amplifying the electrochemical signal. By leveraging the benefits of ABTS cyclic catalysis and the effective electrocatalysis of bioelectrodes based on Co NPs/NS-CNTs, the self-powered biosensor has a broad detection range of 0.1–1000 fM and a low detection limit of 25 aM toward ACE. The proposed signal amplification approach presents a promising strategy for enhancing sensitivity and enabling portable analysis in applications of food safety, environmental monitoring, and medical diagnostics.

Sensitive and selective fluorescence detection of acetamiprid using oxidized single-walled carbon nanohorns and cryonase-assisted signal amplification

To address the low accuracy of pesticide residue detection in traditional Chinese medicine, we developed a biosensor for acetamiprid detection. First, an oxidized single-walled carbon nanohorn capable of adsorbing and quenching fluorescence was prepared. Second, a novel fluorescence sensing system was constructed based on this nanomaterial. The detection performance of the sensor system was evaluated, which revealed that fluorescence quenching by the biosensor was primarily due to the adsorption of the aptamer by the nanomaterials. Optimal conditions were found to be a nanomaterial mass concentration of 800 ng/mL and an incubation time of 70 min, which resulted in the best fluorescence response. Under these optimal conditions, the system was used to detect acetamiprid residues in traditional Chinese medicine. The fluorescence intensity showed a strong linear relationship with acetamiprid concentration, with a correlation coefficient of 0.9985 and a detection limit of 6.33 ng/mL. In the sample test, the biosensor demonstrated high accuracy, with good average recovery rates and low relative standard deviation. The system showed excellent selectivity and detection performance, with no interference from other pesticides.

Electrochemical potential enhanced EC-SERS sensor for sensitive and label-free detection of acetamiprid

Label-free surface-enhanced Raman spectroscopy (SERS) holds promise for detecting pesticide residues, yet its broader application in food safety is limited by the weak affinity between pesticides and SERS substrates. This study introduces an electrochemical surface-enhanced Raman spectroscopy (EC-SERS) sensor that utilizes potential strengthened molecular interactions and Ag@SiO2 nanospheres as SERS substrates, significantly enhancing the detection sensitivity for acetamiprid (AAP). The dense distribution of silver nanoparticles (Ag NPs) on the SiO2 surfaces creates numerous “hot spots,” significantly improving the SERS performance for AAP detection. A potential of −0.5 V substantially boosts the SERS signal intensity for AAP compared to without applied potential, notably achieving a 4.3-fold increase at the 631 cm−1 signal peak. Under optimal conditions, the EC-SERS method achieved a limit of detection (LOD) for AAP at 0.046 μM, spanning a linear range from 0.05 μM to 0.1 mM, which is 185 times more sensitive than conventional SERS approaches. When applied to vegetable samples, the method showed recoveries between 95.56 % and 109.33 %, with results corroborated by HPLC-MS analysis. Thus, this study provides an effective and facile strategy for the detection of AAP in the food safety field.

Ultrasensitive Paper-Based Photoelectrochemical Biosensor for Acetamiprid Detection Enabled by Spin-State Manipulation and Polarity-Switching.

Efficient carrier separation is vitally crucial to improving the detection sensitivity of photoelectrochemical (PEC) biosensors. Here, we developed a facile strategy to efficiently regulate the carrier separation efficiency of the photoactive matrix BiOI and In2S3 signal label functionalized paper chip by manipulation of electrons spin-state and rational design of electron transport pathways. The spin-dependent electronic structures of BiOI and In2S3 were regulated via enhanced electron-spin parallel alignment induced by an external magnetic field, markedly retarding carrier recombination and extending their lifetime. Simultaneously, with the progress of the target-induced catalytic hairpin assembly process, the transfer path of photogenerated carriers was changed, leading to a switch in photocurrent polarity from cathode to anode. This reversed electron transport pathway not only boosted the separation ability of photogenerated electrons but also eliminated false-positive and false-negative signals, thereby further improving the detection sensitivity. As a proof of concept, the well-designed magnetic field-stimulated paper-based PEC biosensor showed highly selectivity and sensitivity for acetamiprid assay with a wide linear range of 1 fM to 20 nM and an ultralow detection limit of 0.73 fM. This work develops a universal strategy for improving the sensitivity of biosensors and exhibits enormous potential in the fields of bioanalysis and clinical diagnosis.

Low-temperature subcritical water dechlorination composites of waste PVC/coal fly ash with powerful sensing activity for chemiluminescent detection of acetamiprid and imidacloprid

Pesticide residues in agricultural products are serious threat to people's health. Real-time monitoring of pesticides residues in the environment and agricultural products posed challenges to sustainable methods with high analytical performance for pesticide detection. Herein, waste PVC/coal fly ash (the mass ratio of PVC and coal fly ash was 4:1) was dechlorinated in subcritical water at low temperature to achieve nearly 100 % dechlorination of PVC and obtain carbon-based composite materials (CM-Fe/Al/Si-dPVC) with strong sening activity. For CM-Fe/Al/Si-dPVC, CFe bonding resulted in strong electron migration, and nano/μm SiO2 and Al2O3 doping in the layered polyene C matrix provided large specific surface area, and silicon hydroxyl created good heterogeneous catalytic interfaces. CM-Fe/Al/Si-dPVC could strongly trigger luminol chemiluminescence (CL) reaction and produce intense CL signals. Neonicotinoid pesticides (acetamiprid and imidacloprid) bonded with CM-Fe/Al/Si-dPVC through coordination chelation and hydrogen bonding, which shielded the catalytic active site and increased the Fermi level of system, thus quenching CL reaction. Inspired by these, a cheap CL assay was constructed for detecting neonicotinoids combinations of acetamiprid and imidacloprid (NICs). The detection limits of NICs were 0.7 ng/L. Satisfactory recoveries were obtained for real agricultural products and environmental samples. The results of life cycle evaluation (LCA) revealed that the strategy had significantly small global warming potential (GWP). This work presented a sustainable method with environmental benefits for the detection of neonicotinoids, and also opened up new way for the recycling of organic solid wastes.

Catalytic hairpin-assembled and DNAzyme-driven DNA walker integrated hybridization chain reaction to construct a label-free electrochemical aptasensor for the detection of acetamiprid

As a new type of nicotine pesticide, the excessive residue of acetamiprid (ACE) in food and the environment seriously poses human health. Hence, this article developed an electrochemical aptasensor for detecting ACE based on a cascaded amplification circuit composed of catalytic hairpin-assembled and DNAzyme-driven DNA walker and hybridization chain reaction. Through the target triggered catalytic hairpin assembly (CHA), the free travelling strand of DNA walker and intact catalytic core of DNAzyme were formed, and with the assistance of Mg2+, DNAzyme was activated, driving the travelling strand to walk autonomously, repeatedly cutting hairpin DNA substrates on the electrode surface, and obtaining abundant DNA fragments. These fragments contained the initiators of hybridization chain reaction (HCR) could trigger HCR and produce the long double-strand DNA (dsDNA) for loading methylene blue (MB). Owing to the fact that Ce(Ⅲ, Ⅳ)-MOF material with electrocatalytic activity, the electrochemical reduction of MB could be effectively catalyzed, obtain significantly enhanced current signals, and ultimately achieve label-free and sensitive detection of ACE, with a detection limit of 16.38 fM (S/N = 3). Moreover, the aptasensor demonstrated excellent selectivity, stability, and reproducibility, and exhibited good reliability for detecting ACE in the vegetable soil and tomato samples, providing a new idea for the detection of pesticide residues in the fields of food and environment.

Cauliflower-like super-hydrophobic SERS substrate via two-step laser processing for acetamiprid detection

Residues of organic pesticides continue to accumulate in the human body through the food chain, posing a serious threat to health. Therefore, the efficient and sensitive detection of pesticide residues is crucial. Surface-enhanced Raman scattering (SERS), as a powerful spectroscopic technique, holds great potential for the trace detection of pesticides. In this study, a cauliflower-like SERS substrate fabricated via a two-step laser processing is proposed for highly sensitive detection of acetamiprid. The cauliflower-like structure features a large surface area, providing numerous hotspots and abundant adsorption sites for the target molecules. Furthermore, the rich micro/nano structures on the surface confer super-hydrophobicity properties to the substrate, effectively enriching the analyte and greatly enhancing the SERS performance. As a result, the cauliflower-like super-hydrophobic substrate demonstrates a detection limit as 10-15 M for the typical dye analyte (R6G), with an enhancement factor of 2.6 × 108. Additionally, the substrate exhibits excellent signal reproducibility with a relative standard deviation of 8.33 %. In practical pesticide detection, the detection limit for acetamiprid on orange is 10-4 g/L, significantly surpassing the national standard. In conclusion, the cauliflower-like super-hydrophobic substrate enhances the sensitivity, uniformity, reproducibility, and reliability of SERS signals in detection process, showing tremendous potential in the field of food safety.

Xác định acetamiprid bằng phương pháp quang học sử dụng dung dịch nano vàng được ổn định bằng Polydiallyldimethylammoni clorua

On this research, the development of a simple, cost-efective and highly sensitive spectrophotometric method for acetamiprid detection based on the localized surface plasmon resonance of polydiallyldimethylammonium chloridestabilized gold nanoparticles. By naked eyes, one can detect acetamiprid by the visual change of gold solution color from red to purple, corresponding to the shift of maximum absorbance wavelength in the UV-Vis spectrum. Quantification of acetamiprid is possible through a linear relationship between the maximum absorbance wavelength and the acetamiprid concentrations in the range of 8×10-8 -2×10-6 M. Under the optimum conditions including pH 5, NaCl concentration of 0.02 M and incubation time 20 min, the present method has high precision (RSD < 5%), very low limit of detection (LOD) of 2.7×10-8 M, limit of quantification (LOQ) of 8.2×10-8 M. This method has been successfully applied to determine acetamiprid in several pesticide samples and vegetable samples. The measurement results of acetamiprid in the pesticide samples of the research method with the HPLC-UV method showed a difference of < 2%, while for the vegetable sample, the difference between the research method and the LC-MS/method method/ MS < 5% shows that the method has high accuracy and reliability.

Multiple signal-enhanced electrochemiluminescence aptamer sensors based on carboxylated ruthenium (II) complexes for acetamiprid detection

BackgroundRapid and sensitive detection for acetamiprid, a kind of widely used neonicotinoid insecticide, is very meaningful for the development of modern agriculture and the protection of human health. Highly stable electrochemiluminescence (ECL) materials are one of the key factors in ECL sensing technology. ECL materials prepared by porous materials (e.g., MOFs) coated with chromophores have been used for ECL sensing detection, but these materials have poor stability because the chromophores escape when they are in aqueous solution. Therefore, the development of highly stable ECL materials is of great significance to improve the sensitivity of ECL sensing technology. ResultsIn this work, by combining etched metal-organic frameworks (E-UIO-66-NH2) as carrier with Tris(4,4′-dicarboxylic acid-2,2′-bipyridine)Ru(II) chloride (Ru(dcbpy)32+) as signal probe via amide bonds, highly stable nanocomposites (E-UIO-66-NH2-Ru) with excellent ECL performance were firstly prepared. Then, using MoS2 loaded with AuNPs as substrate material and co-reactant promoter, a signal off-on-off ECL aptamer sensor was prepared for sensitive detection of acetamiprid. Due to the excellent catalytic activity of E-UIO-66-NH2-Ru and MoS2@Au towards K2S2O8, the ECL signals can be enhanced by multiple signal enhancement pathways, the prepared ECL aptamer sensor could achieve sensitive detection of acetamiprid in the linear range of 10−13 to10−7 mol L−1, with the limit of detection (LOD) of 2.78ⅹ10−15 mol L−1 (S/N = 3). After the evaluation of actual sample testing, this sensing platform was proven to be an effective method for the detection of acetamiprid in food and agricultural products. Significance and noveltyThe E-UIO-66-NH2-Ru prepared by linking Ru(dcbpy)32+ to E-UIO-66-NH2 via amide bonding has very high stability. The synergistic catalytic effect of MoS2 and AuNPs enhanced the ECL signal. By exploring the sensing mechanism and evaluating the actual sample tests, the proposed signal "on-off" ECL sensing strategy was proved to be an effective and excellent ECL sensing method for sensitive and stable detection of acetamiprid.

Metal-organic framework-based aptasensor utilizing a novel electrochemiluminescence system for detecting acetamiprid residues in vegetables

The work was based on N-(4-Aminobutyl)-N-ethylisoluminol (ABEI)-functionalized Fe-MIL-101 and gold nanoparticles (AuNPs) as sensing materials, and an electrochemiluminescence (ECL) aptasensor was constructed for detecting acetamiprid. As a metal-organic framework (MOF) material, Fe-MIL-101, was renowned for its unique three-dimensional network structure and efficient catalytic capability. ABEI, a common ECL reagent, was widely applied. ABEI was introduced into the Fe-MIL-101 structure as a luminescence functionalization reagent to form Fe-MIL-101@ABEI. This approach avoided limitations on the loading capacity of luminescent reagents imposed by modification and encapsulation methods. With character of excellent catalytic activity and ease of bioconjugation, AuNPs offered significant advantages in biosensing. Leveraging the reductive properties of ABEI, AuNPs were reduced around Fe-MIL-101@ABEI, resulting in the modified luminescent functionalized material denoted as Fe-MIL-101@ABEI@AuNPs. An aptamer was employed as a recognition element and was modified accordingly. The aptamer was immobilized on Fe-MIL-101@ABEI@AuNPs through gold-sulfur (Au–S) bonds. After capturing acetamiprid, the aptamer induced a decrease in the ECL signal intensity within the ABEI-hydrogen peroxide (H2O2) system, enabling the quantitative detection of acetamiprid. The aptasensor displayed remarkable stability and repeatability, featured a detection range of 1×10−3-1×102 nM, and had a limit of detection (LOD) of 0.3 pM (S/N=3), which underscored its substantial practical application potential.

Development of aptamer surface-enhanced Raman spectroscopy sensor based on Fe3O4@Pt and Au@Ag nanoparticles for the determination of acetamiprid.

As a common chlorinated nicotinic pesticide with high insecticidal activity, acetamiprid has been widely used for pest control. However, the irrational use of acetamiprid will pollute the environment and thus affect human health. Therefore, it is crucial to develop a simple, highly sensitive, and rapid method for acetamiprid residue detection. In this study, the capture probe (Fe3O4@Pt-Aptamer) was connected with the signal probe (Au@DTNB@Ag CS-cDNA) to form an assembly with multiple SERS-enhanced effects. Combined with magnetic separation technology, a SERS sensor with high sensitivity and stability was constructed to detect acetamiprid residue. Based on the optimal conditions, the SERS intensity measured at 1333cm-1 is in relation to the concentration of acetamiprid in the range 2.25 × 10-9-2.25 × 10-5M, and the calculated limit of detection (LOD) was 2.87 × 10-10M. There was no cross-reactivity with thiacloprid, clothianidin, nitenpyram, imidacloprid, and chlorpyrifos, indicating that this method has good sensitivity and specificity. Finally, the method was applied to the detection of acetamiprid in cucumber samples, and the average recoveries were 94.19-103.58%, with RSD < 2.32%. The sensor can be used to analysereal samples with fast detection speed, high sensitivity, and high selectivity.

Potential powered EC-SERS for sensitive detection of acetamiprid

Surface-enhanced Raman spectroscopy (SERS) is a powerful tool for rapid and sensitive detection of pesticide residues in food, and the applied potential regulated SERS technique can be endowed with a higher sensitivity. In this work, we developed an electrochemical-surface enhanced Raman spectroscopy (EC-SERS) sensor for the rapid detection of acetamiprid (AAP) in vegetables. AuNPs/ITO were prepared via in-situ electrodeposition of gold nanoparticles (AuNPs) on an indium tin oxide (ITO) both as a SERS substrate and working electrode. By adding AAP into an in-situ Raman electrolytic cell with an applied electrochemical potential (+0.3 V), the SERS intensity was enhanced by 4-fold and the characteristic signal was linearly related to the concentration of AAP. Under the optimal conditions, the EC-SERS method exhibited a linear detection range from 0.05 to 50 μM, with a limit of detection (LOD, 3S/M) of 0.02 μM. Simultaneously, based on density functional theory (DFT), the adsorption characteristics of AAP on AuNPs/ITO were studied in the presence of electric field. The method was finally confirmed by HPLC-MS for the detection of real samples, revealing its potential application in food safety.

Detection of acetamiprid residues in vegetables by a self-enhanced bimetallic luminescent MOF-based electrochemiluminescence-electrochemistry dual-mode aptasensor

In this study, a dual-mode aptasensor based on the competition mechanism was constructed to detect acetamiprid (ACE) residues in vegetables. With 3,5-dicarboxyphenylboronic acid (5-bop) as a ligand, a bimetallic RuZn-based metal-organic framework (RuZn-MOF) was synthetized by applying a hydrothermal method to achieve efficient electrochemiluminescence (ECL) and electrochemistry (EC) dual-mode detection of ACE. Compared with the monometallic Zn-based metal-organic framework (Zn-MOF) of the same structure, the bimetallic RuZn-MOF exhibited a greater ability to transfer electrons due to the synergistic effect between different metal and the 5-bop ligand. Meanwhile, the complementary DNA (cDNA) probe for bonding the ACE aptamer was modified with ferrocene (Fc) and methylene blue (MB). When the target pesticide of ACE was present, ACE competed with the cDNA probe, so that the ECL achieved the "signal on" and the EC achieved the "signal off". ECL and EC detection being combined, the results showed that the two detection methods corroborated each other and worked synergistically, i.e., they effectively reduced the systematic errors and background signals, and improved the reliability of the detection. The linear ranges of the ECL and EC aptasensors were 1 pg/mL-1 μg/mL with the limit of detection (LOD) of 0.33 pg/mL, and 1 fg/mL-1 ng/mL with LOD of 0.33 fg/mL (S/N=3), respectively. The dual-mode strategy had good stability and specificity, providing some valuable support for the detection and analysis of other substances.

"Four-In-One" Multifunctional Dandelion-Like Gold@platinum Nanoparticles-Driven Multimodal Lateral Flow Immunoassay.

The traditional lateral flow immunoassay (LFIA) with a single signal output mode may encounter challenges such as low sensitivity, poor detection range, and susceptibility to external interferences. These limitations hinder its ability to meet the growing demand for advanced LFIA. To address these issues, the rational development of multifunctional labels for multimodal LFIA emerges as a promising strategy. Herein, this study reports a multimodal LFIA using "four-in-one" multifunctional dandelion-like gold@platinum nanoparticles (MDGP). The inherent properties of MDGP, such as the broad absorption spectrum, porous dandelion-like nanostructure, and bimetallic composition with gold and platinum, endow them with capacities in dual spectral-overlapped fluorescence quenching, optical readout, catalytic activity, and photothermal effect. Benefiting from their multifunctional properties, the MDGP-LFIA enables multimodal outputs including fluorescent, colorimetric, and photothermal signals. This multimodal MDGP-LFIA allows for the detection of acetamiprid at a range of 0.01-50ngmL-1, with the lowest qualitative and quantitative detection results of 0.5 and 0.008ngmL-1, respectively, significantly better than the traditional gold nanoparticles-based LFIA. The diversity, complementarity, and synergistic effect of integrated output signals in this multimodal MDGP-LFIA improve the flexibility, practicability, and accuracy of detection, holding great promise as a point-of-care testing platform in versatile application scenarios.

An applied potential powered screen-printed electrode for sensitive EC-SERS detection of acetamiprid

Acetamiprid (AAP) is a common neonicotinoid pesticide and their residues have emerged as a widely concerned issue on vegetables and fruits. In this work, a facile electrochemical surface-enhanced Raman spectroscopy (EC-SERS) method with one step of “mixing and detection” was proposed for detection of AAP. Wherein, screen printed electrode (SPE) was modified by dropping silver nanoparticles (AgNPs) onto the SPE surface. Compared to the normal SERS detection, the EC-SERS had a 5-fold enhancement in SERS signal with an applied potential at –0.7 V. Under the optimal applied potential, a wide linear range from 0.1 μM to 1000 μM was achieved with a low limit of detection (LOD, 0.04 μM), about 7-fold lower than that of the normal SERS method (LOD, 0.31 μM). Density functional theory (DFT) calculation revealed that the van der Waals force between AAP molecules and AgNPs was greatly enhanced. Besides, the EC-SERS method was successfully applied for the detection of AAP in Brassica chinensis L., and the results correlated well (R2 =0.9760) with those obtained from liquid chromatography-tandem mass spectrometry (HPLC-MS). The proposed method featured in easy operation, rapid detection and high sensitivity, which can act as a promising tool for monitoring pesticide residues in food samples.

Fluorescent aptasensor mediated with multiple ssDNA for sensitive detection of acetamiprid in vegetables based on magnetic Fe3O4/C-assisted separation.

Acetamiprid (ACE) is a highly effective broad-spectrum insecticide, and its widespread use is potentially harmful to human health and environmental safety. In this study, magnetic Fe3O4/carbon (Fe3O4/C), a derivative of metal-organic framework MIL-101 (Fe), was synthesized by a two-step calcination method. And a fluorescent sensing strategy was developed for the efficient and sensitive detection of ACE using Fe3O4/C and multiple complementary single-stranded DNA (ssDNA). By using aptamer with multiple complementary ssDNA, the immunity of interference of the aptasensor was improved, and the aptasensor showed high selectivity and sensitivity. When ACE was present, the aptamer (Apt) combined with ACE. The complementary strand of Apt (Cs1) combined with two short complementary strands of Cs1, fluorophore 6-carboxyfluorescein-labeled complementary strand (Cs2-FAM) and the other strand Cs3. The three strands formed a double-stranded structure, and fluorescence would not be quenched by Fe3O4/C. In the absence of ACE, Cs2-FAM would be in a single-chain state and would be adsorbed by Fe3O4/C, and the fluorescence of FAM would be quenched by Fe3O4/C via photoelectron transfer. This aptasensor sensitively detected ACE over a linear concentration range of 10-1000nM with a limit of detection of 3.41nM. The recoveries of ACE spiked in cabbage and celery samples ranged from 89.49% to 110.76% with high accuracy.