Novel Au-tetrahedral aptamer nanostructure for the electrochemiluminescence detection of acetamiprid

Conjugated polymer-boosted near-infrared electrochemiluminescence of organic dye for detecting acetamiprid

BACKGROUND

The near-infrared electrochemiluminescence (NIR-ECL) has excellent penetration and near zero background interference, and has shown unique advantages in clinical medicine and bioimaging. Among various types of NIR-ECL emitters, NIR organic dyes have arouse the concern of researchers due to their adjustable structure and diverse optical properties. However, the currently available NIR dyes usually have inherent self-quenching effect and poor photostability, so their ECL efficiency is low, and it is a great challenge to improve their ECL performance.

RESULT

Conjugated polymer-boosted NIR-ECL strategy was creatively developed to overcome ECL performance limitations of NIR dyes. IR 783, as one of heptamethine cyanine dyes, was performed a nanoprecipitation in the presence of poly[(9,9-dlhexyfluoren-2,7-dlyl)-co-(anthracen-9,10-dlyl)] (PFAD) to prepare IR polymer nanoparticles (IR PNPs). Due to resonance energy transfer (RET) from PFAD to IR 783 and encapsulation of IR 783 by PFAD, the resulting IR PNPs exhibited a strong and stable NIR-ECL emission with a maximum ECL wavelength of 802 nm under coreactant tripropylamine (TPrA) and H2O2 can effectively quench it. IR PNPs coupled proximity ligation assay (PLA)-induced DNA walker to achieve acetamiprid (ACE) analysis. ACE triggered PLA to form bipedal DNA walker, and further release G-rich secondary target (ST). With ST and hemin being captured on IR PNPs modified electrode, hemin/G-quadruplex was assembled to consume H2O2, thereby restoring ECL signal for ACE detection with a limit of detection of 4.74 × 10-15 M.

SIGNIFICANCE

This work opens up a new and simple way to boost NIR-ECL of organic dyes, and IR PNPs create a promising NIR-ECL platform for pesticide detection.

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 cross-linkable fluorescent probe with oriented antibody to enhance lateral immunoassay strip for the detection of acetamiprid

Time-resolved fluorescent lateral immunoassay strip (TRFLIS) is a reliable and rapid method for detecting acetamiprid. However, its sensitivity is often affected by the structural patterns and stability of the fluorescent probe. Researchers have shown significant interests in using goat anti-mouse IgG (GaMIgG) which is indirectly bound to time-resolved fluorescent microsphere (TRFM) and antibody. This allowed for oriented modification of the antibody. However, the stability of fluorescent probe in this binding mode remained unexplored. Herein, 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride was innovatively used as a cross-linking agent to enhance the binding of antibody to GaMIgG, which improved the stability of the fluorescent probe. Under optimal working conditions, this strategy exhibited a wide linear response range of 5-700 ng/mL. Its limit of detection (LOD) was 0.62 ng/mL, the visual LOD was 5 ng/mL, and the limit of quantification (LOQ) of 2.06 ng/mL. Additionally, under tomato matrix, leek matrix and Chinese cabbage matrix, the linear response ranges were 5-400, 5-300, and 5-700 ng/mL, with LODs of 0.16, 0.60, and 0.41 ng/mL, with LOQs of 0.53, 2.01 and 1.37 ng/mL, respectively. In conclusion, this strategy effectively reduced the dosage of acetamiprid antibody compared with TRFM directly linking acetamiprid antibody, and greatly increased the sensitivity of TRFLIS. Meanwhile, it demonstrated outstanding specificity and accuracy in acetamiprid detection and had been successfully applied to vegetable samples. This method enables rapid and accurate detection of large-volume samples by combining qualitative and quantitative methods. As such, it has great potential in the development of low-cost and high-performance immunochromatographic platforms.

Nanoporous Gold-Modified Screen-Printed Electrodes for the Simultaneous Determination of Pb2+ and Cu2+ in Water

In this study, nanoporous gold (NPG) was deposited on a screen-printed carbon electrode (SPCE) by the dynamic hydrogen bubble template (DHBT) method to prepare an electrochemical sensor for the simultaneous determination of Pb2+ and Cu2+ by square wave anodic stripping voltammetry (SWASV). The electrodeposition potential and electrodeposition time for NPG/SPCE preparation were investigated thoroughly. Scanning electron microscopy (SEM) and energy-dispersive X-ray diffraction (EDX) analysis confirmed successful fabrication of the NPG-modified electrode. Electrochemical characterization exhibits its superior electron transfer ability compared with bare and nanogold-modified electrodes. After a comprehensive optimization, Pb2+ and Cu2+ were simultaneously determined with linear range of 1-100 μg/L for Pb2+ and 10-100 μg/L for Cu2+, respectively. The limits of detection were determined to be 0.4 μg/L and 5.4 μg/L for Pb2+ and Cu2+, respectively. This method offers a broad linear detection range, a low detection limit, and good reliability for heavy metal determination in drinking water. These results suggest that NPG/SPCE holds great promise in environmental and food applications.

Label/immobilization-free Cas12a-based electrochemiluminescence biosensor for sensitive DNA detection

Electrochemiluminescence (ECL) is one of the most sensitive techniques in the field of diagnostics. However, they typically require luminescent labeling and electrode surface biological modification, which is a time-consuming and laborious process involving multiple steps and may also lead to low reaction efficiency. Fabricating label/modification-free biosensors has become one of the most attractive parts for simplifying the ECL assays. In this work, the ECL luminophores carbon dots (CDs) were encapsulated in DNA hydrogel in situ by a simple rolling circle amplification (RCA) reaction. Upon binding of the target DNA, active Cas12a induces a collateral cleavage of the hydrogel's ssDNA backbone, resulting in a programmable degradation of the hydrogel and the release of CDs. By directly measuring the released CDs ECL, a simple and rapid label/modification-free detection of the target HPV-16 was realized. It is noted that this method allowed for 0.63 pM HPV-16 DNA detection without any amplification step, and it could take only ∼60 min for a fast test of a human serum sample. These results showed that our label/modification-free ECL biosensor has great potential for use in simple, rapid, and sensitive point-of-care (POC) detection.

Ultrasensitive Electrochemiluminescence Biosensing Platform Based on Polymer Dots with Aggregation-Induced Emission for Dual-Biotoxin Assay

Multitarget assay has always been a hot topic in electrochemiluminescence (ECL) methods. Herein, a "on-off-on" ECL aptasensor was developed for the ultrasensitive and sequential detection of possible biological warfare agents, deoxynivalenol (DON) and abrin (ABR). As a luminophore, polymer dots (Pdots) with aggregation-induced emission exhibit high ECL efficiency in the aptasensor, i.e., the signal "on" state. The DON assays mainly depend on ECL quenching due to the efficient quenching effect between ferrocene-H2-ferrocene (Fc-H2-Fc) and Pdots, i.e., the signal "off" state. When the aptasensor is incubated with the oligonucleotide sequence S2 to replace Fc-H2-Fc, obvious ECL recovery occurs, i.e., the signal "on" state, which can be used to sequentially detect ABR. The limit of detection (LOD) for DON is 0.73 fg·mL-1 in the range of 5.0 to 50 ng·mL-1; and the LOD for ABR is ∼0.38 pg·mL-1 in the range of 1.25 pg·mL-1 to 1.25 μg·mL-1. The as-designed ECL aptasensor exhibits good stability and reproducibility, high specificity, and favorable practicality. Therefore, this work provides a new approach for assays of DON and ABR in food safety and can be used as a model to design an ultrasensitive ECL biosensor for multitarget detection.

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.

Electrochemical sensing mechanisms of neonicotinoid pesticides and recent progress in utilizing functional materials for electrochemical detection platforms

The excessive residue of neonicotinoid pesticides in the environment and food poses a severe threat to human health, necessitating the urgent development of a sensitive and efficient method for detecting trace amounts of these pesticides. Electrochemical sensors, characterized by their simplicity of operation, rapid response, low cost, strong selectivity, and high feasibility, have garnered significant attention for their immense potential in swiftly detecting trace target molecules. The detection capability of electrochemical sensors primarily relies on the catalytic activity of electrode materials towards the target analyte, efficient loading of biomolecular functionalities, and the effective conversion of interactions between the target analyte and its receptor into electrical signals. Electrode materials with superior performance play a crucial role in enhancing the detection capability of electrochemical sensors. With the continuous advancement of nanotechnology, particularly the widespread application of novel functional materials, there is paramount significance in broadening the applicability and expanding the detection range of pesticide sensors. This comprehensive review encapsulates the electrochemical detection mechanisms of neonicotinoid pesticides, providing detailed insights into the outstanding roles, advantages, and limitations of functional materials such as carbon-based materials, metal-organic framework materials, supramolecular materials, metal-based nanomaterials, as well as molecular imprinted materials, antibodies/antigens, and aptamers as molecular recognition elements in the construction of electrochemical sensors for neonicotinoid pesticides. Furthermore, prospects and challenges facing various electrochemical sensors based on functional materials for neonicotinoid pesticides are discussed, providing valuable insights for the future development and application of biosensors for simplified on-site detection of agricultural residues.

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 1333 cm-1 is in relation to the concentration of acetamiprid in the range 2.25 × 10-9-2.25 × 10-5 M, and the calculated limit of detection (LOD) was 2.87 × 10-10 M. 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 analyse real samples with fast detection speed, high sensitivity, and high selectivity.

Potential-Resolved Ratiometric Aptasensor for Sensitive Acetamiprid Analysis Based on Coreactant-free Electrochemiluminescence Luminophores of Gd-MOF and "Light Switch" Molecule of [Ru(bpy)2dppz]2

For conventional potential-resolved ratiometric electrochemiluminescence (ECL) systems, the introduction of multiplex coreactants is imperative. However, the undesirable interactions between different coreactants inevitably affect analytical accuracy and sensitivity. Herein, through the coordination of aggregation-induced emission ligands with gadolinium cations, the self-luminescent metal-organic framework (Gd-MOF) is prepared and serves as a novel coreactant-free anodic ECL emitter. By the intercalation of [Ru(bpy)2dppz]2+ with light switch effect into DNA duplex, one high-efficiency cathodic ECL probe is obtained using K2S2O8 as a coreactant. In the presence of acetamiprid, the strong affinity between the target and its aptamer induces the release of [Ru(bpy)2dppz]2+, resulting in a decreasing cathode signal and an increasing anode signal owing to the ECL resonance energy transfer from Gd-MOF to [Ru(bpy)2dppz]2+. In this way, an efficient dual-signal ECL aptasensor is constructed for the ratiometric analysis of acetamiprid, exhibiting a remarkably low detection limit of 0.033 pM. Strikingly, by using only one exogenous coreactant, the cross interference from multiple coreactants can be eliminated, thus improving the detection accuracy. The developed high-performance ECL sensing platform is successfully applied to monitor the residual level of acetamiprid in real samples, demonstrating its potential application in the field of food security.

Novel electrochemiluminescence aptasensor based on AuNPs-ABEI encapsulated TiO2 nanorod for the detection of acetamiprid residues in vegetables

Gold nanoparticles (AuNPs)@N-(4-aminobutyl)-N-ethylisoluminol (ABEI)@Titanium dioxide nanorods (TiO2NRs) were used as sensing materials to produce a unique encapsulated nanostructure aptasensor for the detection of acetamiprid residues in this work. ABEI, an analog of luminol, was extensively used as an electrochemiluminescence (ECL) reagent. The ECL mechanism of ABEI- hydrogen peroxide (H2O2) system had connections to a number of oxygen-centered free radicals. TiO2NRs improved ECL response with high electron transfer and a specific surface area. AuNPs were easy to biolabel and could catalyze H2O2 to enhance ECL signal. AuNPs were wrapped around TiO2NRs by utilizing the reduction property of ABEI to form wrapped modified nanomaterials. The sulfhydryl-modified aptamer bound to the nanomaterial by forming gold-sulfur (Au-S) bonds. The aptamer selectively bound to its target with the addition of acetamiprid, which caused a considerable decrease in ECL intensity and enabled quantitative detection of acetamiprid. The aptasensor showed good stability, repeatability and specificity with a broad detection range (1×10-2-1×103 nM) and a lower limit of detection (3 pM) for acetamiprid residues in vegetables. Overall, this aptasensor presents a simple and highly sensitive method for ECL detecting acetamiprid, with potential applications in vegetable safety monitoring.

A colorimetric sensor array based on peroxidase activity nanozyme for the highly efficient differential sensing of tea polyphenols and Tieguanyin adulteration

Tieguanyin (TGY) is one of top ten famous teas in China, but in the process of brand building there is the phenomenon of falsehood, thus harming the interests of consumers. To solve theadulterate problem of TGY, a colorimetric sensor array (CSA) based onperoxidase activity of nanozyme was constructed. Nanozymes can catalyze 3,3',5,5'-tetramethylbenzidine (TMB) to 3,3',5,5'-tetramethyl -[1,1'-bis(cyclohexyl)]-2,2',5,5'-tetraene-4,4'-diimine (oxTMB), while the tea polyphenols (TPs) can inhibit this process, and the degree of inhibition varies significantly with the reaction time. We selected two nanozymesand three reaction time points to construct CSA. It can successfully distinguish TPsin TGY. The discriminative analysiscan achieve: (1)distinction between TGY and adulterated tea, (2)discrimination of TGY in various seasons and seasonal adulteration in different degrees. The method constructed in this work is promising for both the class and quality differentiation of TGY and other teas with TPs as the main activity.

Portable multichannel detection instrument based on time-resolved fluorescence immunochromatographic test strip for on-site detecting pesticide residues in vegetables

In this work, a portable multichannel detection instrument based on time-resolved fluorescence immunochromatographic test strip (TRFIS) was proposed for on-site detecting pesticide residues in vegetables. Its hardware consisted of a silicon photodiode and excitation light source array, a mainboard of the lower machine with STMicroelectronics 32 (STM32) and a linear stepping motor. While detecting, cardboard with 6-channel TRFIS was pulled into the cassette by the stepping motor. The peak area of the test (T) line and control (C) line of each TRFIS was sampled and calculated by software, then the concentration of the detected pesticide was obtained according to the ratio of the T to C value. This instrument could sample 6-channel TRFIS within 30 s simultaneously, and it exhibited excellent accuracy with a 2.5% average coefficient of variation for each channel (n = 12). In addition, the TRFIS was constructed by using europium oxide time-resolved fluorescent microspheres to label the monoclonal antibody against acetamiprid and form a fluorescent probe, which was fixed on the binding pad. The TRFIS was used for the detection of acetamiprid in celery cabbage, cauliflower and baby cabbage. This instrument was used to complete the qualitative and quantitative analysis of the TRFIS, so as to enhance the practical application of the detection method. This TRFIS possessed excellent linearity ranging from 0.25 mg kg-1 to 1.75 mg kg-1 for the detection of acetamiprid, and the limit of detection were 0.056-0.074 mg kg-1 in the different vegetable matrix. The platform combines the accuracy and portability of traditional test strips with the highly sensitive and efficient fluorescence intensity recognition function of detection equipment, which shows a great application prospect of multi-channel rapid detection of small molecule pollutants in the field.

Zeolitic imidazolate framework/aptamer-based fluorescence assay for the facile and high-sensitivity detection of acetamiprid

Accurate monitoring of trace pesticides in complex matrix remains a challenge in food safety supervision. Herein, we designed a facile zeolitic imidazolate framework (ZIF)-8/aptamer-based assay for the sensitive detection of acetamiprid. ZIF-8 efficiently adsorbs 6-carboxyfluorescein-labeled complementary DNA (cDNA-FAM) via electrostatic interaction, hydrogen bonding and Zn2+ coordination, which contributed to resistance to cDNA-FAM displacement by biological ligands. ZIF-8 serves as an "ion pump" that contains lots of Zn2+ who boosts cDNA-FAM adsorption and triggers the photoinduced electron transfer (PET) effect from FAM to ZIF-8, improving the sensing sensitivity. Acetamiprid could trigger the change in the adsorption state of cDNA-FAM, further tuning the PET effect and causing fluorescence conversion. The fluorescence assay showed a high sensitivity for monitoring acetamiprid with a detection limit of 0.05 ng mL-1 in the apple sample. This ZIF/DNA-based analytical platform provides a powerful tool for facile and low-cost screening of pesticide residues, with promising applications in food safety monitoring.

Emerging Insights into the Use of Advanced Nanomaterials for the Electrochemiluminescence Biosensor of Pesticide Residues in Plant-Derived Foodstuff

Pesticides have an important role in rising the overall productivity and yield of agricultural foods by eliminating and controlling insects, pests, fungi, and various plant-related illnesses. However, the overuse of pesticides has caused pesticide pollution of water bodies and food products, along with disruption of environmental and ecological systems. In this regard, developing low-cost, simple, and rapid-detecting approaches for the accurate, rapid, efficient, and on-site screening of pesticide residues is an ongoing challenge. Electrochemiluminescence (ECL) possesses the benefits of great sensitivity, the capability to resolve several analytes using different emission wavelengths or redox potentials, and excellent control over the light radiation in time and space, making it a powerful strategy for sensing various pesticides. Cost-effective and simple ECL systems allow sensitive, selective, and accurate quantification of pesticides in agricultural fields. Particularly, the development and progress of nanomaterials, aptamer/antibody recognition, electric/photo-sensing, and their integration with electrochemiluminescence sensing technology has presented the hopeful potential in reporting the residual amounts of pesticides. Current trends in the application of nanoparticles are debated, with an emphasis on sensor substrates using aptamer, antibodies, enzymes, and molecularly imprinted polymers (MIPs). Different strategies are enclosed in labeled and label-free sensing along with luminescence determination approaches (signal-off, signal-on, and signal-switch modes). Finally, the recent challenges and upcoming prospects in this ground are also put forward.

CRISPR/Cas12a-Mediated Aptasensor Based on Tris-(8-hydroxyquinoline)aluminum Microcrystals with Crystallization-Induced Enhanced Electrochemiluminescence for Acetamiprid Analysis

Improving the electrochemiluminescence (ECL) efficiency of luminophores has always been the goal of the ECL field. Herein, a novel crystallization-induced enhanced ECL (CIE ECL) strategy was exploited to significantly enhance the ECL efficiency of metal complex tris-(8-hydroxyquinoline)aluminum (Alq₃). Alq₃ monomers self-assembled and directionally grew to form Alq₃ microcrystals (Alq₃ MCs) in the presence of sodium dodecyl sulfate. The highly ordered crystal structure of Alq₃ MCs not only constrained the intramolecular rotation of Alq₃ monomers to decrease nonradiative transition but also accelerated the electron transfer between Alq₃ MCs and coreactant tripropylamine to increase radiative transition, thus leading to a CIE ECL effect. Alq₃ MCs exhibited brilliant anode ECL emission, which was 210-fold stronger than that of Alq₃ monomers. The exceptional CIE ECL performance of Alq₃ MCs coupled the efficient trans-cleavage activity of CRISPR/Cas12a assisted by rolling circle amplification and catalytic hairpin assembly to fabricate a CRISPR/Cas12a-mediated aptasensor for acetamiprid (ACE) detection. The limit of detection was as low as 0.79 fM. This work not only innovatively exploited a CIE ECL strategy to enhance the ECL efficiency of metal complexes but also integrated CRISPR/Cas12a with a dual amplification strategy for the ultrasensitive monitoring of pesticides such as ACE.

Dual-ratiometric aptasensor for simultaneous detection of malathion and profenofos based on hairpin tetrahedral DNA nanostructures

Due to the diversification and complexity of organophosphorus pesticide residues brings great challenges to the detection work. Therefore, we developed a dual-ratiometric electrochemical aptasensor that could detect malathion (MAL) and profenofos (PRO) simultaneously. In this study, metal ions, hairpin-tetrahedral DNA nanostructures (HP-TDN) and nanocomposites were used as signal tracers, sensing framework and signal amplification strategy respectively to develop the aptasensor. Thionine (Thi) labeled HP-TDN (HP-TDNThi) provided specific binding sites for assembling Pb2+ labeled MAL aptamer (Pb2+-APT1) and Cd2+ labeled PRO aptamer (Cd2+-APT2). When the target pesticides were present, Pb2+-APT1 and Cd2+-APT2 were dissociated from the hairpin complementary strand of HP-TDNThi, resulting in reduced oxidation currents of Pb²⁺ (I_Pb²⁺) and Cd²⁺ (I_Cd²⁺), respectively, while the oxidation currents of Thi (I_Thi) remained unchanged. Thus, I_Pb²⁺/I_Thi and I_Cd²⁺/I_Thi oxidation current ratios were used to quantify MAL and PRO, respectively. In addition, the gold nanoparticles (AuNPs) encapsulated in the zeolitic imidazolate framework (ZIF-8) nanocomposites (Au@ZIF-8) greatly increased the catch of HP-TDN, thereby amplifying the detection signal. The rigid three-dimensional structure of HP-TDN could reduce the steric hindrance effect on the electrode surface, which could greatly improve the recognition efficiency of the aptasensor for the pesticide. Under the optimal conditions, the detection limits of the HP-TDN aptasensor for MAL and PRO were 4.3 pg mL-1 and 13.3 pg mL-1, respectively. Our work proposed a new approach to fabricating a high-performance aptasensor for simultaneous detection of multiple organophosphorus pesticides, opening a new avenue for the development of simultaneous detection sensors in the field of food safety and environmental monitoring.

A convenient fluorescent/electrochemical dual-mode biosensor for accurate detection of Pb2+ based on DNAzyme cycle

The presence of heavy metals in the ecological environment is a serious threat to human health. Therefore, it is very important to establish a simple and sensitive method for the detection of heavy metals. Currently, most of the methods are single-channel sensing, and these methods are prone to false-positive signals, which reduces the accuracy. In this work, Pb²⁺-DNAzyme was immobilized on magnetic beads (MBs) using a linkage of biotin and streptavidin and successfully applied to the construction of a fluorescent/electrochemical dual-mode (DM) biosensor. The supernatant after magnetic separation formed a double strand on the electrode, which was combined with methylene blue (MB) for electrochemical detection (EC). At the same time, FAM-d was added to the precipitate, and after magnetic separation, the supernatant was subjected to fluorescent detection (FL). Under optimal conditions, the signal response of the constructed dual-mode biosensor showed a good linear relationship with the concentration of Pb²⁺. The DNAzyme-based dual-mode biosensor achieved sensitive and selective detection of Pb²⁺ with good accuracy and reliability, opening a new way for the development of biosensing strategies for the detection of Pb²⁺. More importantly, the sensor has high sensitivity and accuracy for the detection of Pb²⁺ in actual sample analysis.

Integration of Metallic Nanomaterials and Recognition Elements for the Specifically Monitoring of Pesticides in Electrochemical Sensing

Although all countries have been controlling the excessive use of pesticides, incidents of pesticide residues still existed. Electrochemical biosensors are extensively applied detection techniques to monitor pesticides with the help of different types of biorecognition components mainly including, antibodies, aptamers, enzymes (i.e., acetylcholinesterase, organophosphorus hydrolase, etc.), and synthetic molecularly imprinted polymers. Besides, the electrode materials mainly affected the sensitivity of electrochemical biosensors. Metallic nanomaterials with various structures and excellent electrical conductivity were desirable choice to construct electrochemical platforms to achieve the detection with high sensitivity and good specificity toward the target. This work reviewed the developed metallic materials including monometallic nanoparticles, bimetallic nanomaterials, metal atoms, metal oxides, metal molybdates, metal-organic frameworks, MXene, etc. Integration of recognition elements endowed the electrode materials with higher specificity toward the target pesticide. Besides, future challenges of metallic nanomaterials-based electrochemical biosensors for the detection of pesticides are also discussed and described.

Nanomaterials-Based Electrochemiluminescence Biosensors for Food Analysis: Recent Developments and Future Directions

Developing robust and sensitive food safety detection methods is important for human health. Electrochemiluminescence (ECL) is a powerful analytical technique for complete separation of input source (electricity) and output signal (light), thereby significantly reducing background ECL signal. ECL biosensors have attracted considerable attention owing to their high sensitivity and wide dynamic range in food safety detection. In this review, we introduce the principles of ECL biosensors and common ECL luminophores, as well as the latest applications of ECL biosensors in food analysis. Further, novel nanomaterial assembly strategies have been progressively incorporated into the design of ECL biosensors, and by demonstrating some representative works, we summarize the development status of ECL biosensors in detection of mycotoxins, heavy metal ions, antibiotics, pesticide residues, foodborne pathogens, and other illegal additives. Finally, the current challenges faced by ECL biosensors are outlined and the future directions for advancing ECL research are presented.

Novel colorimetric aptasensor based on MOF-derived materials and its applications for organophosphorus pesticides determination

For the visual detection of four organophosphorus pesticides (OPs), a colorimetric aptasensor was developed based on aptamer-mediated bimetallic metal-organic frameworks (MOFs) nano-polymers. Fe-Co magnetic nanoparticles (MNPs) and Fe-N-C nanozymes were prepared based on pyrolytic reaction, and were labeled with broad spectrum aptamers and complementary chains of organophosphorus pesticides respectively. The hybridization of aptamers and complementary chains led to the formation of nano-polymers. In the presence of target pesticides, they competed with complementary chains for aptamers on Fe-Co MNPs, resulting in a large number of Fe-N-C nanozymes signal labels being released into the supernatant. Fe-N-C nanozymes showed similar activity to peroxidase and catalyzed the 3,3',5,5'-tetramethylbenzidine-hydrogen peroxide (TMB-H₂O₂) color system to turn the solution blue-green under mild conditions. The magnetic probes had good selectivity and sensitivity, and were easily separated by magnetic absorption. The sensor functioned well under optimal conditions, demonstrating good stability and specificity for four pesticides: phorate, profenofos, isocarbophos and omethoate, and the detection limits of four pesticides were as low as 0.16 ng/mL, 0.16 ng/mL, 0.03 ng/mL and 1.6 ng/mL respectively, and the recovery rate of OPs residue in vegetable samples was satisfactory. The work described here provided a simple, rapid and sensitive way to construct a biosensor.

A novel conductive nanocomposite-based biosensor for ultrasensitive detection of microRNA-21 in serum, using methylene blue as mediator

MicroRNA-21 (miRNA-21) is a common biomarker with high expression in breast tumors. Therefore, sensitive detection of miRNA-21 is of great significance for clinical breast tumor diagnosis. A TH/rGO/CMK-3/AuNPs nanocomposite is composed of thionine (TH), reduced graphene oxide (rGO), ordered mesoporous carbon (CMK-3), and gold nanoparticles (AuNPs), which help to increase the specific surface area of a glassy carbon electrode (GCE) and to amplify the DPV signal. Meanwhile, methylene blue (MB) was combined with the capture probe guanine and absorbed by the composite material to mediate the differential pulse voltammetry (DPV) of the obtained miRNA biosensor. The current response decreased with increasing miRNA-21 concentration under optimal conditions. The biosensor responds to miRNA-21 in the 0.1fM-1 pM concentration range, and the detection limit (LOD) was 0.046 fM. Moreover, human serum samples were effectively detected utilizing the miRNA-21 biosensor with satisfactory results.

Electrochemical determination of acetamiprid using PEDOT sensing coating functionalized with carbon quantum dots and Prussian blue nanoparticles

A dual-mode electrochemical biosensor for acetamiprid detection was proposed for the first time based on carbon quantum dots/Prussian blue (CQDs/PB)-functionalized poly(3,4-ethylenedioxythiphene) (PEDOT) nanocomposite. The nanocomposite with spherical stacking nanostructure showed high surface area, excellent catalytic ability, and cycling stability. The biosensor can be effortlessly constructed after the immobilization of acetamiprid aptamer. The concentration of acetamiprid can be determined by differential pulse voltammetry (DPV) based on its signal change deduced from the pristine PB. With the capture of acetamiprid, the response current (I-T) signal generated by hydrogen peroxide catalysis from the biosensor can also been used to establish the method for monitoring acetamiprid. The dual-mode biosensor showed a wide linear range from 10^-12 g mL^-1 to 10^-6 g mL^-1, low detection limits of 6.84 × 10^-13 g mL^-1 and 4.99 × 10^-13 g mL^-1, and ultrafast detection time of 25 s and 5 s through DPV and I-T mode, respectively. The biosensor possessed excellent selectivity and stability. More importantly, the biosensor was successfully applied to detect acetamiprid residues in vegetables, proving a promising approach for routine detection of pesticide in real samples. The biosensor based on PEDOT/CQDs/PB for acetamiprid can be effortlessly constructed through both the increase of differential pulse voltammetry (DPV) signal change deduced by the pristine PB and the decrease of the response current (I-T) signal of the reduction of hydrogen peroxide catalyzed by PEDOT/CQDs/PB.

Mitigating toxicity of acetamiprid removal techniques - Fe modified zeolites in focus

All remediation pathways in aqueous solutions come down to three dominant ones - physical, chemical, and combinations thereof. Materials proposed for adsorption and oxidative degradation can induce positive or negative effects on cells compared to the pollutants themselves. Present research deals with the effects different methods for pesticide remediation have and how they impact cytotoxicity. With this particular intention, Fe-modified zeolites (obtained via citrate/oxalate complexes) of three zeotypes (MFI, BEA and FAU) were prepared and tested as adsorbents and Fenton catalysts for the removal of the acetamiprid pesticide. The materials are characterized by AFM, FTIR spectroscopy and ICP-OES. A different effect of the zeolite framework and modification route was found among the samples, which leads to pronounced adsorption (FAU), efficient Fenton degradation (MFI) or synergistic effect of both mechanisms (BEA). The cytotoxic effects of acetamiprid in the presence of zeolites, in pristine and modified forms, were tested on the MRC-5 human fibroblast cell line. A complete survey of the toxicity effect behind different pesticide removal methods is presented. Since neither adsorption nor catalytic degradation is the best option for pesticide removal, the focus is shifted to a combination of these methods, which proved to be optimal for pesticide toxicity reduction.

Interference-resistant aptasensor with tetrahedral DNA nanostructure for profenofos detection based on the composites of graphene oxide and polyaniline

In this work, an interference-resistant electrochemical aptasensor that could detect profenofos in vegetables was constructed based on complexes of graphene oxide and polyaniline (GO@PANI) and gold nanoparticles-tetrahedral DNA nanostructure (Au-TDN). Compared with a single chain aptamer, the tetrahedral DNA nanostructure is highly stable and allows the aptamer on this structure to stand in a highly ordered position on an electrode surface. Moreover, the AuNPs are biocompatible and can protect the activity of the aptamer, which can improve the assembly success rate of Au-TDN. Besides, the conductivity of PANI had been tremendously enhanced thanks to the existence of GO, which improved the dispersion of PANI. The GO@PANI was prepared by a chemical synthesis method, which had a large surface area and was able to adsorb many Au-TDN. Under optimal working parameters, the constructed aptasensor exhibited good electrochemical sensing performance with a detection limit of 10.50 pg/mL and a linear range of 1.0 × 10²-1.0 × 10⁷ pg/mL. In addition, it was employed in detecting profenofos in vegetables with a good recovery rate of 90.41-116.37 %. More importantly, the aptasensor also has excellent stability and high selectivity. This study provides a promising method to avoid interference in the detection of profenofos by sensors.

Dual-Target Electrochemical Sensor Based on 3D MoS2-rGO and Aptamer Functionalized Probes for Simultaneous Detection of Mycotoxins

A dual-target aptamer functionalized probes (DTAFP) was applied for the detection of aflatoxin B1 (AFB1) and zearalenone (ZEN) simultaneously, which has not been reported. Meanwhile, two functional materials for signal amplification of the DTAFP were synthesized: 1) a three-dimensional molybdenum disulfide-reduced graphene oxide (MoS₂-rGO) as a favorable loading interface; 2) a double-probes gold nanoparticles (AuNPs) modified by Thionin (Thi) and 6-(Ferrocenyl) hexanethiol (FC6S) as distinguishable and non-interfering signals. Mycotoxins on the electrode surface release into solution under the function of the DTAFP, leading a reduction of the differential peak impulse in signal response. Under the optimum conditions, the aptasensor exhibited a detection range of 1.0 pg mL⁻¹–100 ng mL⁻¹ for AFB1 and ZEN, with no observable cross reactivity. In addition, the aptasensor performed excellent stability, reproducibility, specificity, and favorable recovery in the detection of edible oil. This work demonstrated a novel method for the construction of a simple, rapid, and sensitive aptasensor in the detection of multiple mycotoxins simultaneously.

Advanced screening and tailoring strategies of pesticide aptamer for constructing biosensor

The rapid development of aptamers has helped address the challenges presented by the wide existed pesticides contaminations. Screening of aptamers with excellent performance is a prerequisite for successfully constructing biosensors, while further tailoring of aptamers with enhanced activity greatly improved the assay performance. Firstly, this paper reviewed the advanced screening strategies for pesticides aptamers, including immobilization screening that preserves the native structures of targets, non-immobilized screening based on nanomaterials, capillary electrophoresis-systematic evolution of ligands by exponential enrichment (CE-SELEX), virtual screening in silico, high-throughput selection, and rational secondary library generation methods, which contributed significantly to improve the success rate of screening, reduce the screening time, and ensure aptamer binding affinity. Secondly, the precise tailoring strategies for pesticides aptamers were modularly elaborated, containing deletion, splitting, elongation, and fusion, which provided various advantages like cost-efficiency, enhanced binding affinity, and new derived functional motifs. Thirdly, the developed aptamer-based biosensors (aptasensors) for pesticide detection were systematically reviewed according to the different signal output modes. Finally, the challenges and future perspectives of pesticide detection are discussed comprehensively.

Effective Electrochemiluminescence Aptasensor for Detection of Atrazine Residue

According to the chemiluminescence characteristics of the luminol-hydrogen peroxide (H₂O₂) system, this work designed a novel and effective electrochemiluminescence (ECL) aptasensor to detect atrazine (ATZ) rapidly. Silver nanoparticles (AgNPs) could effectively catalyze the decomposition of H₂O₂ and enhance the ECL intensity of the luminol-H₂O₂ system. Once ATZ was modified on the aptasensor, the ECL intensity was significantly weakened because of the specific combination between ATZ and its aptamer. Therefore, the changes in ECL intensity could be used to detect the concentration of ATZ. Under optimal detecting conditions, the aptasensor had a wide linear range from 1 × 10⁻³ ng/mL to 1 × 10³ ng/mL and a low limit of detection (3.3 × 10⁻⁴ ng/mL). The designed aptasensor had the advantages of good stability, reproducibility, and specificity. The aptasensor could be used to detect the ATZ content of tap water, soil, and cabbage and had satisfactory results. This work effectively constructs a novel, effective, and rapid ECL aptasensor for detecting ATZ in actual samples.

A novel label-free electrochemiluminescence aptasensor using a tetrahedral DNA nanostructure as a scaffold for ultrasensitive detection of organophosphorus pesticides in a luminol-H2O2 system

In this work, a new type of Au-tetrahedral DNA nanostructure (Au-TDN) was originally proposed and successfully applied in an electrochemiluminescence aptasensor to detect organophosphorus pesticides (Ops). The aptamers modified with -SH could be covalently bonded with gold nanoparticles (AuNPs) to form a tetrahedron structure, and there were independent probes at each vertex of the tetrahedron, which could increase the probability of specific binding with Ops. The originally designed structure could not only maintain a stable tetrahedral configuration, but also combined with the target to improve the sensitivity of the sensor. Meanwhile, silver nanoparticles (AgNPs) could catalyze the chemical reaction between luminol and H₂O₂ to generate a variety of intermediates called reactive oxygen species (ROS) for signal enhancement. Factors that had important influences on the aptasensor, such as the concentration of Au-TDN, the incubation time, and the pH value of the buffer, were optimized in this trial. According to the final results, the limit of detection (LOD) of 3 pg mL^-1 (S/N = 3) for methyl parathion, the LOD of 0.3 pg mL^-1 (S/N = 3) for parathion and the LOD of 0.03 pg mL^-1 (S/N = 3) for phoxim were obtained, respectively. Moreover, the novel tetrahedral structure could be replaced by different types of aptamers to expand its application range and lay a foundation for the development of portable rapid detection devices for pesticide residues.

A gold nanoparticle-based visual aptasensor for rapid detection of acetamiprid residues in agricultural products using a smartphone

Based on the colorimetric analysis of gold nanoparticles and a smartphone readable strategy, a stable, sensitive, and visual method was established for rapid detection of acetamiprid residues in agricultural products. By optimizing the key parameters, the detection process only took 40 minutes with good specificity. The acetamiprid aptamer can help AuNPs to resist salt-induced aggregation. Conversely, in the presence of acetamiprid, the anti-protection is weakened and the AuNPs aggregated with the color change of the solution. The photographs of the solution are recorded by the smartphone and analyzed through image processing. In the range from 25 to 300 μM the method can realize a quantitative analysis of acetamiprid, and the detection limit is about 3.81 μM. Excellent recoveries are taken in samples of cucumber, cabbage, and river water, ranging from 96.78% to 129.95%. These results show no significant difference from the results obtained by the microplate reader. What's more, the method employs a smartphone to read without the assistance of professional equipment, which greatly reduces the cost of detection, and shows a promising application prospect for on-site rapid detection of acetamiprid.

A novel electrochemiluminescence aptasensor based on copper-gold bimetallic nanoparticles and its applications

In this work, a novel electrochemiluminescence (ECL) aptasensor was structured for the detection of four organophosphorus pesticides (OPs). Firstly, multi-walled carbon nanotubes (MWCNTs) were used to create a favorable loading interface for the fixation of tris (2, 2'-bipyridyl) ruthenium (II) (Ru (bpy)₃²⁺). At the same time, copper (core)-gold (shell) bimetallic nanoparticles (Cu@Au NPs) were synthesized in the aqueous phase for the sensor construction. Gold nanoparticles (Au NPs) could promote the electrochemiluminescence intensity of Ru (bpy)₃²⁺ with high efficiency by catalyzing the oxidation process of tri-n-propylamine (TPrA). Compared with the Au NPs, Cu@Au NPs increased the solid loading of Au NPs by virtue of the large specific surface area of copper nanoparticles (Cu NPs), which could further improve the sensitivity of aptasensor. When OPs were added, the ECL intensity was significantly reduced, and the concentration of OPs could be detected through the ECL intensity. Under the optimum conditions, the aptasensor had a wider dynamic range and ultra-low detection limit for the detection of four pesticides: profenofos, isocarbophos, phorate, and omethoate, and their detection limits were 3 × 10^-4 ng/mL, 3 × 10^-4 ng/mL, 3 × 10^-3 ng/mL, and 3 × 10^-2 ng/mL respectively (S/N = 3). The aptasensor had the merits of good stability, reproducibility, and specificity, and had a favorable recovery rate in detecting OPs residues in vegetables. This work provided an effective method for the construction of a simple, rapid, and sensitive biosensor.

A Simple and Novel Sensor for the Determination of Acetamiprid Based on Its Reducing Effect on the Chemiluminescence of S, N-CQDs in CH3CN-H2O2 System

A simple and novel method for the determination of acetamiprid in water samples is suggested. The method is based on the reducing effect of acetamiprid on the chemiluminescence intensity of new sulfur and nitrogen co-doped carbon dots (S, N-CQDs) in an acetonitrile-hydrogen peroxide (CH₃CN-H₂O₂) system. The possible mechanism was investigated, and it was found that S, N-CQDs react with (¹O₂)₂*, produced from the CH₃CN-H₂O₂ reaction, leading to excited state S, N-CQDs, which deactivate to the ground state by photon emission. Acetamiprid diminishes the chemiluminescence (CL) intensity by competing with S, N-CQDs. The CL intensity reduction is proportional to the concentration of acetamiprid. S, N-CQDs were easily prepared by a hydrothermal method. Under the optimal conditions, a linear range of 2.5 - 25.0 μg L^-1 with a detection limit (3σ) of 0.4 μg L^-1 was obtained. This method was successfully applied to the determination of trace amounts of residual pesticides in water samples.

Human-like performance umami electrochemical biosensor by utilizing co-electrodeposition of ligand binding domain T1R1-VFT and Prussian blue

Over the past decades, due to the desire for artificial umami flavors, apparatuses for detecting the umami taste have constantly been developed. Nevertheless, most information on umami is still acquired through human sensory assessment, which makes it difficult to establish an umami standard or quantify the umami flavor. In this study, the ligand binding domain called venus flytrap (VFT) domain of the umami taste receptor protein T1R1 was used as a recognition element, and an electrochemical biosensor based on a double-signal amplification strategy was constructed using single-walled carbon nanotubes (SWCNTs) and Prussian blue (PB). Moreover, the umami taste of four representative umami substances, inosine-5'-monophosphate (IMP), monosodium L-glutamate (MSG), beefy meaty peptide (BMP), and sodium succinate (WSA), were successfully quantitatively measured using differential pulse voltammetry (DPV) at an electrochemical workstation. Based on an equation (S/N = 3), the low detection limits (LODs) of IMP, MSG, BMP, and WSA were 0.1, 0.1, 0.1, and 0.01 pM, respectively. Meanwhile, a normalized signal intensity of more than 90% was kept for 4 days. The results showed that the biosensor could be used to detect umami substances with high sensitivity and selectivity, and was shown to have human-like performance. To develop the T1R1-VFT biosensor using the above-mentioned method, we utilized the ligand binding domain of the human umami receptor, rather than the entire umami receptor protein, which had a complex structure, having the following advantages: volume reduction, simplicity, and stability. This method has great potential for the detection of umami tastes, instead of using sensory evaluation, and for the development of new artificial flavorings.

Aptamer Recognition-Driven Homogeneous Electrochemical Strategy for Simultaneous Analysis of Multiple Pesticides without Interference of Color and Fluorescence

Credible and simultaneous determination of multiple pesticides is highly desirable for guaranteeing food safety. However, the current methods are limited to significant interference of color and fluorescence or electrode's modification and mainly focus on the analysis of a single pesticide. Herein, we proposed a novel aptamer-based homogeneous electrochemical system for highly sensitive and simultaneous analysis of multiple pesticides based on target pesticide-switched exonuclease III (Exo III)-assisted signal amplification. The recognition of hairpin probes by target pesticides impels the production of pesticide-DNA complexes, which hybridize with electroactive dye-labeled DNA to form double-stranded DNA, subsequently initiating an Exo III-assisted digestion reaction to generate abundant electroactive dye-tagged mononucleotides. In comparison with pesticide deficiency, two higher differential pulse voltammetry (DPV) currents are measured, which rely on the amount of target pesticides. Therefore, simultaneous analysis of two pesticides is realized with limits of detection of 0.0048 and 0.0089 nM, respectively, comparable or superior to those of known methods that focused on a single pesticide. Moreover, the proposed system is successfully employed to simultaneously evaluate the residual level of acetamiprid and profenofos in Brassica chinensis and thus will find more useful applications for pesticide-related food safety.

An electrochemical platform based on a hemin-rGO-cMWCNTs modified aptasensor for sensitive detection of kanamycin

Kanamycin (KANA) residue in meat is particularly harmful to public health and there is an urgent need to establish a fast, accurate and low-cost method to determinate KANA in food quality control. In this paper, hemin-reduced graphene oxide-carboxylated multiwalled carbon nanotubes (hemin-rGO-cMWCNTs) were designed and prepared, and the characteristics of hemin-rGO-cMWCNTs are presented. After that, an aptamer/hemin-rGO-cMWCNTs sensor for determination of KANA was developed. The electrochemical characteristics were studied by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). Under optimal conditions, the sensitive response of the aptasensor towards KANA presented a wide concentration range of 10-9 to 10-6 M and a low detection limit of 0.36 nM (S/N = 3). Meanwhile, the aptasensor showed prominent selectivity, high stability and acceptable reproducibility in the application of KANA detection. In addition, the aptasensor detection in real samples correlated well with that obtained by liquid chromatograph mass spectrometer (LCMS).

Determination of acetamiprid using electrochemiluminescent aptasensor modified by MoS2QDs-PATP/PTCA and NH2-UiO-66

A novel aptasensor has been fabricated based on the resonance energy transform (RET) system from MoS₂QDs-PATP/PTCA (donor) to NH₂-UiO-66 (acceptor). The electrochemiluminescence (ECL) signal of PTCA was greatly amplified due to the decoration of MoS₂QDs-PATP, and the NH₂-UiO-66 was utilized to label the signal probe DNA (pDNA), which hybridizes with the exposed aptamer anchored on the surface of MoS₂QDs-PATP/PTCA. With the target acetamiprid, the specific binding of acetamiprid to aptamer causes the connection between the donor and the acceptor to be interrupted and produce an "on" ECL signal. Thus, an "off-on" ECL sensing platform for sensitive and selective acetamiprid assay was designed. Under the optimal condition, the ECL signal of the aptasensor was found to be linearly related to the logarithm of the acetamiprid concentration ranging from 0.1 fM to 0.1 μM with a detection limit of 0.064 fM. More importantly, the recovery rate of the ECL aptasensor was calculated to be 98.7 ~ 106% with a RSD lower 5.1% for the residual acetamiprid assay in real food samples, which indicated that the aptasensor has high potential for practical applications.

Point-of-Care Diagnoses and Assays Based on Lateral Flow Test

Analytical devices for point-of-care diagnoses are highly desired and would improve quality of life when first diagnoses are made early and pathologies are recognized soon. Lateral flow tests (LFTs) are such tools that can be easily performed without specific equipment, skills, or experiences. This review is focused on the use of LFT in point-of-care diagnoses. The principle of the assay is explained, and new materials like nanoparticles for labeling, new recognition molecules for interaction with an analyte, and new additional instrumentation like signal scaling by a smartphone camera are described and discussed. Advantages of the LFT devices as well as their limitations are described and discussed here considering actual papers that are properly cited.

Electrochemical sensor based on glassy carbon electrode modified by polymelamine formaldehyde/graphene oxide nanocomposite for ultrasensitive detection of oxycodone

Polymelamine formaldehyde/graphene oxide (PMF/GO) nanocomposite was used, for the first time, to study the ultrasensitive and selective electrochemical detection of oxycodone (OXC). The successful characterization of PMF/GO was verified based on scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), and Raman spectroscopy. The modified GCE (PMF/GO-GCE) proved its electrocatalytic effect on OXC determination according to cyclic, linear sweep, and differential pulse voltammetry (CV, LSV, and DPV) and electrochemical impedance spectroscopy (EIS) studies. The developed sensor under optimal conditions offered a linear relationship in a limited range of  0.01 to 45 μmol L^-1 with the limit of detection (LOD) of 2.0 nmol L^-1. The proposed PMF/GO-GCE sensor was effectively employed for the OXC detection in human urine and serum samples. Graphical abstract.