Electrochemical Detection of Nucleic Acids Using Three-Dimensional Graphene Screen-Printed Electrodes.

Electrochemical approaches, along with miniaturization of electrodes, are increasingly being employed to detect and quantify nucleic acid biomarkers. Miniaturization of the electrodes is achieved through the use of screen-printed electrodes (SPEs), which consist of one to a few dozen sets of electrodes, or by utilizing printed circuit boards. Electrode materials used in SPEs include glassy carbon (Chiang H-C, Wang Y, Zhang Q, Levon K, Biosensors (Basel) 9:2-11, 2019), platinum, carbon, and graphene (Cheng FF, He TT, Miao HT, Shi JJ, Jiang LP, Zhu JJ, ACS Appl Mater Interfaces 7:2979-2985, 2015). There are numerous modifications to the electrode surfaces as well (Cheng FF, He TT, Miao HT, Shi JJ, Jiang LP, Zhu JJ, ACS Appl Mater Interfaces 7:2979-2985, 2015). These approaches offer distinct advantages, primarily due to their demonstrated superior limit of detection without amplification. Using the SPEs and potentiostats, we can detect cells, proteins, DNA, and RNA concentrations in the nanomolar (nM) to attomolar (aM) range. The focus of this chapter is to describe the basic approach adopted for the use of SPEs for nucleic acid measurement.

Ti3C2 MXene/MoS2@AuNPs ternary nanocomposite for highly sensitive electrochemical detection of phoxim residues in fruits.

Phoxim, extensively utilized in agriculture as an organothiophosphate insecticide, has the potential to cause neurotoxicity and pose human health hazards. In this study, an electrochemical enzyme biosensor based on Ti3C2 MXene/MoS2@AuNPs/AChE was constructed for the sensitive detection of phoxim. The two-dimensional multilayer structure of Ti3C2 MXene provides a robust framework for MoS2, leading to an expansion of the specific surface area and effectively preventing re-stacking of Ti3C2 MXene. Additionally, the synergistic effect of self-reduced grown AuNPs with MoS2 further improves the electrical conductivity of the composites, while the robust framework provides a favorable microenvironment for immobilization of enzyme molecules. Ti3C2 MXene/MoS2@AuNPs electrochemical enzyme sensor showed a significant response to phoxim in the range of 1 × 10-13 M to 1 × 10-7 M with a detection limit of 5.29 × 10-15 M. Moreover, the sensor demonstrated excellent repeatability, reproducibility, and stability, thereby showing its promising potential for real sample detection.

Recent advances in electrochemical approaches for detection of nitrite in food samples.

Nitrite is a common ingredient in the industry and agriculture; it is everywhere, like water, food, and surroundings. Recently, several approaches have been developed to measure the nitrite levels. So, this review was presented as a summary of many approaches utilized to detect the nitrite. Furthermore, the types of information that may be acquired using these methodologies, including optic and electrical signals, were discussed. In electrical signal methods, electrochemical sensors are usually developed using different materials, including carbon, polymers, oxides, and hydroxides. At the same time, optic signals receiving techniques involve utilizing fluorescence chromatography, absorption, and spectrometry instruments. Furthermore, these methodologies' benefits, drawbacks, and restrictions are examined. Lastly, due to the efficiency and fast means of electrochemical detectors, it was suggested that they can be used for detecting nitrite in food safety. Futuristic advancements in the techniques used for nitrite determination are subsequently outlined.

A highly sensitive electrochemical sensor based on poly(3-aminobenzoic acid)/graphene oxide-gold nanoparticles modified screen printed carbon electrode for paraquat detection.

Herein, a modified screen printed carbon electrode (SPCE) based on a composite material, graphene oxide-gold nanoparticles (GO-AuNPs), and poly(3-aminobenzoic acid)(P3ABA) for the detection of paraquat (PQ) is introduced. The modified electrode was fabricated by drop casting of the GO-AuNPs, followed by electropolymerization of 3-aminobenzoic acid to achieve SPCE/GO-AuNPs/P3ABA. The morphology and microstructural characteristics of the modified electrodes were revealed by scanning electron microscopy (SEM) for each step of modification. The composite GO-AuNPs can provide high surface area and enhance electroconductivity of the electrode. In addition, the presence of negatively charged P3ABA notably improved PQ adsorption and electron transfer rate, which stimulate redox reaction on the modified electrode, thus improving the sensitivity of PQ analysis. The SPCE/GO-AuNPs/P3ABA offered a wide linear range of PQ determination (10-9-10-4 mol/L) and low limit of detection (LOD) of 0.45 × 10-9 mol/L or 0.116 µg/L, which is far below international safety regulations. The modified electrode showed minimum interference effect with percent recovery ranging from 96.5% to 116.1% after addition of other herbicides, pesticides, metal ions, and additives. The stability of the SPCE/GO-AuNPs/P3ABA was evaluated, and the results indicated negligible changes in the detection signal over 9 weeks. Moreover, this modified electrode was successfully implemented for PQ analysis in both natural and tapped water with high accuracy.

Electrochemical removal of nitrate in high-salt wastewater with low-cost iron electrode modified by phosphate.

Nitrate (NO3-) is a widespread pollutant in high-salt wastewater and causes serious harm to human health. Although electrochemical removal of nitrate has been demonstrated to be a promising treatment method, the development of low-cost electro-catalysts is still challenging. In this work, a phosphate modified iron (P-Fe) cathode was prepared for electrochemical removal of nitrate in high-salt wastewater. The phosphate modification greatly improved the activity of iron, and the removal rate of nitrate on P-Fe was three times higher than that on Fe electrode. Further experiments and density functional theory (DFT) calculations demonstrated that the modification of phosphoric acid improved the stability and the activity of the zero-valent iron electrode effectively for NO3- removal. The nitrate was firstly electrochemically reduced to ammonium, and then reacted with the anodic generated hypochlorite to N2. In this study, a strategy was developed to improve the activity and stability of metal electrode for NO3- removal, which opened up a new field for the efficient reduction of NO3- removal by metal electrode materials.

Support electron inductive effect of Pd-Mn/Ni foam catalyst for robust electrocatalytic hydrodechlorination.

Structural regulation of Pd-based electrocatalytic hydrodechlorination (EHDC) catalyst for constructing high-efficient cathode materials with low noble metal content and high atom utilization is crucial but still challenging. Herein, a support electron inductive effect of Pd-Mn/Ni foam catalyst was proposed via in-situ Mn doping to optimize the electronic structure of the Ni foam (NF), which can inductive regulation of Pd for improving the EHDC performance. The mass activity and current efficiency of Pd-Mn/NF catalyst are 2.91 and 1.34 times superior to that of Pd/NF with 2,4-dichlorophenol as model compound, respectively. The Mn-doped interlayer optimized the electronic structure of Pd by bringing the d-state closer to the Fermi level than Pd on the NF surface, which optimizied the binding of EHDC intermediates. Additionally, the Mn-doped interlayer acted as a promoter for generating H* and accelerating the EHDC reaction. This work presents a simple and effective regulation strategy for constructing high-efficient cathode catalyst for the EHDC of chlorinated organic compounds.

Exploring the impact of fulvic acid on electrochemical hydrogen-driven autotrophic denitrification system: Performance, microbial characteristics and mechanism.

In this study, the effect of modulating fulvic acid (FA) concentrations (0, 25 and 50 mg/L) on nitrogen removal in a bioelectrochemical hydrogen autotrophic denitrification system (BHDS) was investigated. Results showed that FA increased the nitrate (NO3--N) removal rate of the BHDSs from 37.8 to 46.2 and 45.2 mg N/(L·d) with a current intensity of 40 mA. The metagenomic analysis revealed that R2 (25 mg/L) was predominantly populated by autotrophic denitrifying microorganisms, which enhanced denitrification performance by facilitating electron transfer. Conversely, R3 (50 mg/L) exhibited an increase in genes related to the heterotrophic process, which improved the denitrification performance through the collaborative action of both autotrophic and heterotrophic denitrification pathways. Besides, the study also identified a potential for nitrogen removal in Serpentinimonas, which have been rarely studied. The interesting set of findings provide valuable reference for optimizing BHDS for nitrogen removal and promoting specific denitrifying genera within the system.

The portable stochastic sensor as a screening tool for simultaneous determination of HER-1 and CA 125 - a key factor in the rapid recognition of gastric cancer.

The significance of HER-1 and CA 125 lies in their ability to guide cancer diagnosis, treatment, and monitoring, improving personalized care and enhancing prognostic accuracy. The utilization of HER-1 and CA 125 as screening biomarkers for the anticipation of early-stage cancer and monitoring cancer progression is expanding due to the invasive and costly nature of present techniques. In this study, a novel stochastic sensor was developed for the simultaneous determination of HER-1 and CA 125 in whole blood, saliva, and gastric tumor tissue samples using a fast, easy, inexpensive, and portable method. The stochastic sensor was prepared by electropolymerization of cysteine on the surface of the Au-TiO2@rGO/SPCE sensor. The Au-TiO2@rGO nanocomposite was synthesized using a simple chemical reduction process. The proposed sensor showed wide linear concentration ranges and very low limits of quantification (LOQ). The concentration ranges were from 3.9 × 10-14 to 3.9 × 10-8 µg mL-1, with a LOQ of 3.9 × 10-14 µg mL-1 for HER-1. For CA 125, the concentration ranges were from 8.3 × 10-14 to 8.3 × 10-10 U mL-1, with a LOQ of 8.3 × 10-14 U mL-1. Both biomarkers exhibit precise discrimination in different biological samples, with recoveries above 96.78% and RSD values below 0.04%. With a confidence level of 99%, the Student t-test revealed that there is no statistically significant difference between the outcomes obtained by using the poly-Cys/Au-TiO2@rGO/SPCE sensor for screening examinations of biological samples. This was determined because the results were not significantly different from one another.

Label-free SELEX of aptamers for ultra-sensitive electrochemical aptasensor detection of amanitin in wild mushrooms.

BACKGROUND: Mushroom poisoning poses a significant global health concern, with high morbidity and mortality rates. The primary lethal toxins responsible for this condition are alpha-amanitin (ɑ-AMA) and beta-amanitin (ß-AMA). As a promising bio-recognition molecules in biosensors, aptamers, have been broadly used in the field of food detection. However, the current SELEX-based methods for screening aptamers for structurally similar small molecules were limited by the labelling or salt ion induction. In this study, we aimed to develop a novel label-free SELEX strategy for the screening of aptamers with high affinity and constructed new aptasensors for the detection of ɑ-AMA and ß-AMA. RESULTS: A novel label-free SELEX strategy based on the positively charged gold nanoparticles (AuNPs) was proposed to simultaneous screening of aptamers for ɑ-AMA and ß-AMA. Only 18 rounds of SELEX were required to obtain new aptamers. The candidate aptamers were analyzed by colloidal gold assay, and the sequences of ɑ-30 and ß-37 displayed great affinity with Kd values of 22.26 nM and 23.32 nM, respectively, without interference from botanical toxins. Notably, the truncated aptamers ɑ-30-2 (50 bp) and ß-37-2 (57 bp) exhibited higher affinity than their original counterpart (79 bp). Subsequently, the selected aptamers were utilized to construct recognition probes for electrochemical aptasensors based on hairpin cyclic cleavage of substrates by Cu2+ dependent DNAzyme and Exo I-triggered recycling cascades. The detection platform showed excellent analytical performance with limits of detection as low as 4.57 pg/mL (ɑ-AMA) and 8.49 pg/mL (ß-AMA). Moreover, the aptasensors exhibited superior performance in mushroom and urine samples. SIGNIFICANCE: This work developed a simple and efficient label-free SELEX method for screening new aptamers for ɑ-AMA and ß-AMA, which employed the positively charged AuNPs as the screening medium, without the need for chemical labelling of libraries or induction of salt ions. Furthermore, two novel electrochemical aptasensors were developed based on our newly obtained aptamers, which offer the new biosensing tool for ultrasensitive detection of the AMA poisoning, showing great potential in practical applications.

Ultrasonically assisted fabrication of electrochemical platform for tinidazole detection.

Based on sonochemistry, green synthesis methods play an important role in the development of nanomaterials. In this work, a novel chitosan modified MnMoO4/g-C3N4 (MnMoO4/g-C3N4/CHIT) was developed using ultrasonic cell disruptor (500 W, 30 kHz) for ultra-sensitive electrochemical detection of tinidazole (TNZ) in the environment. The morphology and surface properties of the synthesized MnMoO4/g-C3N4/CHIT electrode were characterized using X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM) and transmission electron microscope (TEM). Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques were utilized to assess the electrochemical performance of TNZ. The results indicate that the electrochemical detection performance of TNZ is highly efficient, with a detection limit (LOD) of 3.78 nM, sensitivity of 1.320 µA·µM-1·cm-2, and a detection range of 0.1-200 µM. Additionally, the prepared electrode exhibits excellent selectivity, desirable anti-interference capability, and decent stability. MnMoO4/g-C3N4/CHIT can be successfully employed to detect TNZ in both the Songhua River and tap water, achieving good recovery rates within the range of 93.0 % to 106.6 %. Consequently, MnMoO4/g-C3N4/CHIT's simple synthesis might provide a new electrode for the sensitive, repeatable, and selective measurement of TNZ in real-time applications. Using the MnMoO4/g-C3N4/CHIT electrode can effectively monitor and detect the concentration of TNZ in environmental water, guiding the sewage treatment process and reducing the pollution level of antibiotics in the water environment.

Solid-state Ru(bpy)32+ electrochemiluminescence sensor for trace detection of fenpropathrin using loofah sponge-like carbon nanofibers and CdS.

Loofah sponge-like carbon nanofibers (LF-Co,N/CNFs) were utilized as a carrier for Ru(bpy)32+, and then combined with CdS to create a novel solid-state electrochemiluminescence sensor capable of detecting trace amounts of fenpropathrin. LF-Co,N/CNFs, obtained through the high-temperature pyrolysis of ZIF-67 coaxial electrospinning fibers, were characterized by a loofah-like morphology and exhibited a significant specific surface area and porosity. Apart from serving as a carrier, LF-Co,N/CNFs also functioned as a luminescence accelerator, enhancing the system's luminescence efficiency by facilitating electron transmission and reducing the transmission distance. The inclusion of CdS in the luminescence reaction, in conjunction with Ru(bpy)32+, further boosted the sensor's luminescence signal. The resulting sensor demonstrated a satisfactory signal, with fenpropathrin causing significant quenching of the ECL signal. Under optimized conditions, a linear relationship between the signal quench value and fenpropathrin concentration in the range 1 × 10-12 to 1 × 10-6 M was observed, with a detection limit of 3.3 × 10-13 M (S/N = 3). This developed sensor is characterized by its simplicity, sensitivity, and successful application in detecting fenpropathrin in real samples. The study not only presents a straightforward detection platform for fenpropathrin but also introduces new avenues for the rapid determination of various food contaminants, thereby expanding the utility of carbon fibers in electrochemiluminescence sensors.

An electrochemical sensor based on porous heterojunction hollow NiCo-LDH/Ti3C2Tx MXenes composites for the detection of quercetin in natural plants.

Cubic hollow-structured NiCo-LDH was synthesized using a solvothermal method. Subsequently, clay-like Ti3C2Tx MXenes were electrostatically self-assembled with NiCo layered double hydroxides (NiCo-LDH) to form composites featuring three-dimensional porous heterostructures. The composites were characterized using SEM, TEM, XRD, XPS, and FT-IR spectroscopy. Ti3C2Tx MXenes exhibit excellent electrical conductivity and hydrophilicity, providing abundant binding sites for NiCo-LDH, thereby promoting an increase in ion diffusion channels. The formation of three-dimensional porous heterostructural composites enhances charge transport, significantly improving sensor sensitivity and response speed. Consequently, the sensor demonstrates excellent electrochemical detection capability for quercetin (Qu), with a detection range of 0.1-20 µM and a detection limit of 23 nM. Additionally, it has been applied to the detection of Qu in natural plants such as onion, golden cypress, and chrysanthemum. The recovery ranged from 97.6 to 102.28%.

Characterizing Mediated Extracellular Electron Transfer in Lactic Acid Bacteria with a Three-Electrode, Two-Chamber Bioelectrochemical System.

Many bacteria perform extracellular electron transfer (EET), whereby electrons are transferred from the cell to an extracellular terminal electron acceptor. This electron acceptor can be an electrode and electrons can be delivered indirectly via a redox-active mediator molecule. Here, we present a protocol to study mediated EET in Lactiplantibacillus plantarum, a probiotic lactic acid bacterium widely used in the food industry, using a bioelectrochemical system. We detail how to assemble a three-electrode, two-chambered bioelectrochemical system and provide guidance on characterizing EET in the presence of a soluble mediator using chronoamperometry and cyclic voltammetry techniques. We use representative data from 1,4-dihydroxy-2-naphthoic acid (DHNA)-mediated EET experiments with L. plantarum to demonstrate data analysis and interpretation. The techniques described in this protocol can open new opportunities for electro-fermentation and bioelectrocatalysis. Recent applications of this electrochemical technique with L. plantarum demonstrated an acceleration of metabolic flux towards producing fermentation end-products, which are critical flavor components in food fermentation. As such, this system has the potential to be further developed to alter flavors in food production or produce valuable chemicals.

Signal amplification in molecular sensing by imprinted polymers.

In the field of sensing, the development of sensors with high sensitivity, accuracy, selectivity, sustainability, simplicity, and low cost remains a key focus. Over the past decades, optical and electrochemical sensors based on molecular imprinting techniques have garnered significant attention due to the above advantages. Molecular imprinting technology utilizes molecularly imprinted polymers (MIPs) to mimic the specific recognition capabilities of enzymes or antibodies for target molecules. Recently, MIP-based sensors rooting in signal amplification techniques have been employed to enhance molecular detection level and the quantitative ability for environmental pollutants, biomolecules, therapeutic compounds, bacteria, and viruses. The signal amplification techniques involved in MIP-based sensors mainly cover nucleic acid chain amplification, enzyme-catalyzed cascade, introduction of high-performance nanomaterials, and rapid chemical reactions. The amplified analytical signals are centered around electrochemical, fluorescence, colorimetric, and surface-enhanced Raman techniques, which can effectively realize the determination of some low-abundance targets in biological samples. This review highlights the recent advancements of electrochemical/optical sensors based on molecular imprinting integrated with various signal amplification strategies and their dedication to the study of trace biomolecules. Finally, future research directions on developing multidimensional output signals of MIP-based sensors and introducing multiple signal amplification strategies are proposed.

Electrochemical Aptasensor with Antifouling Properties for Label-Free Detection of Oxytetracycline.

Oxytetracycline (OTC) is a widely employed antibiotic in veterinary treatment and in the prevention of infections, potentially leaving residues in animal-derived food products, such as milk, that are consumed by humans. Given the detrimental effects of prolonged human exposure to antibiotics, it has become imperative to develop precise and sensitive methods for monitoring the presence of OTC in food. Herein, we describe the development and results of a preliminary label-free electrochemical aptasensor with antifouling properties designed to detect OTC in milk samples. The sensor was realized by modifying a gold screen-printed electrode with α-lipoic acid-NHS and an amine-terminated aptamer. Different electrochemical techniques were used to study the steps of the fabrication process and to quantify OTC in the presence of the Fe(CN)64-/Fe(CN)63- redox couple The detectable range of concentrations satisfy the maximum residue limits set by the European Union, with an limit of detection (LOD) of 14 ng/mL in phosphate buffer (BP) and 10 ng/mL in the milk matrix, and a dynamic range of up to 500 ng/mL This study is a steppingstone towards the implementation of a sensitive monitoring method for OTC in dairy products.

Electrochemical Sensors for Antibiotic Detection: A Focused Review with a Brief Overview of Commercial Technologies.

Antimicrobial resistance (AMR) poses a significant threat to global health, powered by pathogens that become increasingly proficient at withstanding antibiotic treatments. This review introduces the factors contributing to antimicrobial resistance (AMR), highlighting the presence of antibiotics in different environmental and biological matrices as a significant contributor to the resistance. It emphasizes the urgent need for robust and effective detection methods to identify these substances and mitigate their impact on AMR. Traditional techniques, such as liquid chromatography-mass spectrometry (LC-MS) and immunoassays, are discussed alongside their limitations. The review underscores the emerging role of biosensors as promising alternatives for antibiotic detection, with a particular focus on electrochemical biosensors. Therefore, the manuscript extensively explores the principles and various types of electrochemical biosensors, elucidating their advantages, including high sensitivity, rapid response, and potential for point-of-care applications. Moreover, the manuscript investigates recent advances in materials used to fabricate electrochemical platforms for antibiotic detection, such as aptamers and molecularly imprinted polymers, highlighting their role in enhancing sensor performance and selectivity. This review culminates with an evaluation and summary of commercially available and spin-off sensors for antibiotic detection, emphasizing their versatility and portability. By explaining the landscape, role, and future outlook of electrochemical biosensors in antibiotic detection, this review provides insights into the ongoing efforts to combat the escalating threat of AMR effectively.

Magnetic Porous Hydrogel-Enhanced Wearable Patch Sensor for Sweat Zinc Ion Monitoring.

Wearable sensors for sweat trace metal monitoring have the challenges of effective sweat collection and the real-time recording of detection signals. The existing detection technologies are implemented by generating enough sweat through exercise, which makes detecting trace metals in sweat cumbersome. Generally, it takes around 20 min to obtain enough sweat, resulting in dallied and prolonged detection signals that cannot reflect the endogenous fluctuations of the body. To solve these problems, we prepared a multifunctional hydrogel as an electrolyte and combined it with a flexible patch electrode to realize real-time monitoring of sweat Zn2+. Such hydrogel has magnetic and porous properties, and the porous structure of hydrogel enables a fast absorption of sweat, and the magnetic property of the addition of fabricated Fe3O4 NPs not only improves the conductivity but also ensures the adjustable internal structures of the hydrogel. Such a sensing platform for sweat Zn2+ monitoring shows a satisfied linear relationship in the concentration range of 0.16-16 µg/mL via differential pulsed anodic striping voltammetry (DPASV) and successfully detects the sweat Zn2+ of four volunteers during exercise and resting, displaying a promising path for commercial application.

Applications of an Electrochemical Sensory Array Coupled with Chemometric Modeling for Electronic Cigarettes.

This study investigates the application of an eNose (electrochemical sensory array) device as a rapid and cost-effective screening tool to detect increasingly prevalent counterfeit electronic cigarettes, and those to which potentially hazardous excipients such as vitamin E acetate (VEA) have been added, without the need to generate and test the aerosol such products are intended to emit. A portable, in-field screening tool would also allow government officials to swiftly identify adulterated electronic cigarette e-liquids containing illicit flavorings such as menthol. Our approach involved developing canonical discriminant analysis (CDA) models to differentiate formulation components, including e-liquid bases and nicotine, which the eNose accurately identified. Additionally, models were created using e-liquid bases adulterated with menthol and VEA. The eNose and CDA model correctly identified menthol-containing e-liquids in all instances but were only able to identify VEA in 66.6% of cases. To demonstrate the applicability of this model to a commercial product, a Virginia Tobacco JUUL product was adulterated with menthol and VEA. A CDA model was constructed and, when tested against the prediction set, it was able to identify samples adulterated with menthol 91.6% of the time and those containing VEA in 75% of attempts. To test the ability of this approach to distinguish commercial e-liquid brands, a model using six commercial products was generated and tested against randomized samples on the same day as model creation. The CDA model had a cross-validation of 91.7%. When randomized samples were presented to the model on different days, cross-validation fell to 41.7%, suggesting that interday variability was problematic. However, a subsequently developed support vector machine (SVM) identification algorithm was deployed, increasing the cross-validation to 84.7%. A prediction set was challenged against this model, yielding an accuracy of 94.4%. Altered Elf Bar and Hyde IQ formulations were used to simulate counterfeit products, and in all cases, the brand identification model did not classify these samples as their reference product. This study demonstrates the eNose's capability to distinguish between various odors emitted from e-liquids, highlighting its potential to identify counterfeit and adulterated products in the field without the need to generate and test the aerosol emitted from an electronic cigarette.

Pd Nanoparticles Loaded on Cu Nanoplate Sensor for Ultrasensitive Detection of Dopamine.

The detection of dopamine is of great significance for human health. Herein, Pd nanoparticles were loaded on Cu nanoplates (Pd/Cu NPTs) by a novel liquid phase reduction method. A novel dopamine (DA) electrochemical sensor based on the Pd NPs/Cu/glass carbon electrode (Pd/Cu NPTs/GCE) was constructed. This sensor showed a wide linear range of 0.047 mM to 1.122 mM and a low limit of detection (LOD) of 0.1045 µM (S/N = 3) for DA. The improved performance of this sensor is attributed to the obtained tiny Pd nanoparticles which increase the catalytic active sites and electrochemical active surface areas (ECSAs). Moreover, the larger surface area of two-dimensional Cu nanoplates can load more Pd nanoparticles, which is another reason to improve performance. The Pd/Cu NPTs/GCE sensor also showed a good reproducibility, stability, and excellent anti-interference ability.

An Electrochemical Nucleic Acid Biosensor for Triple-Negative Breast Cancer Biomarker Detection.

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer, affecting younger women and women of minorities. The nomenclature "triple negative" is derived from the absence of the three most common breast cancer biomarkers: progesterone receptor (PR), estrogen receptor (ER), and human epidermal growth factor receptor 2 (HER2). It derives its name from testing negative for these three most common breast cancer biomarkers. Currently, TNBC is diagnosed at advanced stages, necessitating the need for a diagnostic tool or method to identify this malignancy at an early stage prior to metastasis. In this study, a novel electrochemical biosensor was developed, optimized, and evaluated for the detection of microRNA-10b (miRNA-10b), marking the first use of this biomarker for the early diagnosis of TNBC. The biosensor demonstrated the ability to detect concentrations as low as 10 pM. Furthermore, the biosensor was specific toward the target biomarker, distinguishing non-target miRNAs of similar size. The efficacy of the biosensor for TNBC early diagnosis was further validated using human serum samples.