Enhanced Detection Sensitivity Research Articles

A simple SERS sensor based on antibody-modified Fe3O4@Au MNPs for the detection of CA19-9 in CRC patients.

This paper presents functionalized magnetic nanoparticles (Fe3O4@Au MNPs) combined with the surface-enhanced Raman spectroscopy (SERS) technique for sensitive detection of colorectal cancer (CRC) protein biomarker carbohydrate antigen 19-9 (CA19-9). Fe3O4@Au MNPs were constructed by the PEI-mediated seed growth method. Then, the signal molecule 5-5'-dithiobis (succinimidyl-2-nitrobenzoic acid) was used as a bridging agent to link CA19-9 antibody, and the SERS sensor was prepared. Using this sensor, detection of CA19-9 can be realized with only a one step sampling reaction. Fe3O4@Au MNPs combine the advantages of magnetic materials and noble metal nanoparticles, effectively amplifying the signal by creating numerous "hot spots" within the Au particle gaps and enhancing magnetic enrichment. Consequently, this approach lowers the detection limit (LOD) and enhances detection sensitivity. The ratio of characteristic peak intensities I1392/I1069 was selected for calculation, and a linear equation was constructed with a LOD as low as 0.27 U mL-1 by quantitative detections of the standard antigen. Finally, the sensor was used to analyze the clinical serum samples from CRC patients and healthy individuals, and the detection results were consistent with the actual results. This method exhibits notable advantages, including simplicity, high sensitivity, specificity, stability and reproducibility. It is expected to provide a new promising analytical method for clinical CA19-9 immunoassay.

Advances in Surface-Enhanced Raman Spectroscopy for Therapeutic Drug Monitoring.

Therapeutic drug monitoring (TDM) is pivotal for optimizing drug dosage regimens in individual patients, particularly for drugs with a narrow therapeutic index. Surface-enhanced Raman spectroscopy (SERS) has shown great potential in TDM due to high sensitivity, non-destructive analysis, specific fingerprint spectrum, low sample consumption, simple operation, and low ongoing costs. Due to the rapid development of SERS for TDM, a review focusing on the analytical method is presented to better understand the trends. This review examines the latest advancements in SERS substrates and their applications in TDM, highlighting the innovations in substrate design that enhance detection sensitivity and selectivity. We discuss the challenges faced by SERS for TDM, such as substrate signal reproducibility and matrix interference from complex biological samples, and explore solutions like digital colloid-enhanced Raman spectroscopy, enrichment detection strategies, microfluidic SERS, tandem instrument technologies, and machine learning-enabled SERS. These advancements address the limitations of traditional SERS applications and improve analytical efficiency in TDM. Finally, conclusions and perspectives on future research directions are presented. The integration of SERS with emerging technologies presents a transformative approach to TDM, with the potential to significantly enhance personalized medicine and improve patient outcomes.

Enhancement of Methane Detection in Tunable Diode Laser Absorption Spectroscopy Using Savitzky–Golay Filtering

In order to enhance gas absorption efficiency and improve the detection sensitivity of methane, a gas absorption cell with an effective optical path length of 29.37 m was developed, employing tunable diode laser absorption spectroscopy (TDLAS) and a distributed feedback (DFB) laser with a center wavelength of 1.654 μm as the light source. However, despite these advancements, the detection accuracy was still limited by potential signal interference and noise. To address these challenges, the Savitzky–Golay (S-G) filtering technique was implemented to optimize the TDLAS detection signal. Experimental results indicated a significant enhancement in detection performance. For a methane concentration of 92 ppm, the application of the S-G filter improved the signal-to-noise ratio by a factor of 1.84, resulting in a final device detection accuracy of 0.53 ppm. This improvement demonstrates the effectiveness of the S-G filter in enhancing detection sensitivity, supporting high-precision methane monitoring for atmospheric analysis and various industrial applications.

LRET-Based Simultaneous Detection of Dual miRNAs via Multitrap Optical Tweezers Assisted Suspension Array Tagged by Two Different Luminescent Quenchable UCNPs Combining CRISPR/Cas12a Amplification.

Nowadays, optical tweezers play a vital role not only in optical manipulation but also in bioassay. As principal optical trapping objects, microbeads can combine optical tweezers with suspension array technology, with amply focused laser beams and adequately concentrated tags contributing to highly sensitive detection. In view of the inefficiency of conventional single-trap optical tweezers, multitrap systems are developed. Here, green- and blue-emitting core-shell-shell upconversion nanoparticles (UCNPs) are adopted to encode microbeads and determine dual miRNAs, with the internal shells leading the luminescence process to facilitate quenching through luminescence resonance energy transfer (LRET). Utilizing the trans cleavage of CRISPR/Cas12a, quenched luminescence signals are recovered and amplified, causing further enhanced detection sensitivity. Ultimately, limits of detection (LOD) of 17 and 22 aM are obtained with excellent specificities verified. Furthermore, dual miRNAs from MCF-7, A549, and MCF-10A cells are extracted and detected, with results consistent with those obtained by PCR. Notably, miR-155 in MCF-7 and A549 cells is detectable at the single-cell level. Thus, the differences in the measured miRNA levels between MCF-7 and MCF-10A cells imply the potential of this method to discriminate breast cancer cells from epithelial cells despite the difficulty in distinguishing different cancer cells due to similar miRNA levels.

Widening of Dynamic Detection Range in Real-Time Angular-Interrogation Surface Plasmon Resonance Biosensor Based on Anisotropic Van Der Waals Heterojunction.

Surface plasmon resonance (SPR) biosensors have experienced rapid development in recent years and have been widely applied in various fields. Angular-interrogation SPR biosensors play an important role in the field of biological detection due to their advantages of reliable results and high stability. However, angular-interrogation SPR biosensors also suffer from low detection sensitivity, poor real-time performance, and limited dynamic detection range, which seriously restricts their application and promotion. Therefore, we designed an angular-interrogation SPR biosensor based on black phosphorus (BP)/graphene two-dimensional (2D) van der Waals heterojunction (vdWhs). On the basis of using the angle-fixed method, this biosensor not only has good real-time performance but also detection sensitivity enhancement. The optical anisotropy characteristic of BP is used to widen the dynamic detection range of biosensors. The simulation results show that the maximum detection sensitivity of the proposed biosensor is 258.6 deg/RIU. Compared with the bare-Ag film structure biosensor, the detection sensitivity was enhanced by 209.2% by 2D vdWhs. The use of anisotropic 2D material BP can not only enhance the detection sensitivity but also widen the detection range. When the fixed incident angle is θ = 5 deg, a maximum dynamic detection range enhanced factor of 123.1% can be achieved, and a detection sensitivity of 185.2 deg/RIU in the corresponding interval can be obtained. The proposed biosensor in this study has potential broad application prospects in several fields, such as biological detection.

Transparent ultrasonic transducers based on relaxor ferroelectric crystals for advanced photoacoustic imaging

Photoacoustic imaging is a promising non-invasive functional imaging modality for fundamental research and clinical diagnosis. However, achieving capillary-level resolution, wide field-of-view, and high frame rates remains challenging. To address this, we propose a transparent ultrasonic transducer design using our developed transparent Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 crystals. Our fabrication technique incorporates quartz-glass-and-epoxy matching layers with low-resistance indium-tin-oxide electrodes through a brass-ring based structure, enabling a high frequency (28.5 MHz), wide bandwidth (78%), and enhanced pulse-echo sensitivity (2.5 V under 2-μJ pulse excitation). Our Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3-based transparent ultrasonic transducer demonstrates a four-fold enhancement in photoacoustic detection sensitivity when compared to the LiNbO3-based counterpart, leading to a 13 dB improvement of signal-to-noise ratio in microvascular photoacoustic imaging. This enables dynamic monitoring of mouse cerebral cortex microvasculature during seizures at 0.8 Hz frame rates over a 1.5 × 1.5 mm2 field-of-view. Our work paves the way for high-performance and compact photoacoustic imaging systems using advanced piezoelectric materials.

Electrophoresis and Quartz Crystal Microbalance Instrumentation to Sense Nanoplastics in Water.

We report a Technical Note on detecting nanoplastics in water samples through electrophoresis and quartz crystal microbalance (QCM) instrumentation. We conducted electrophoresis experiments by immersing a QCM in a sample of ultrapure water containing polyethylene (PE) nanoplastics. It was interesting to observe that nanoplastics were attracted toward the QCM and adhered to one side of the QCM electrode. The attached particles introduced mass loading to the QCM and were characterized by a decrease in resonance frequency of the crystal. Furthermore, when a small region around the center of electrode was alone exposed for direct contact in water and the rest of the electrode was masked using photoresist, the nanoplastics were concentrated only in the exposed electrode region, significantly enhancing detection sensitivity. To further investigate the applicability for real-life water samples, we experimented with the technique with readily available bottled drinking water and mineral water, where we spiked these water samples with nanoplastics. It was observed that the resonance frequency shifts were significantly larger for samples with nanoplastics compared to samples without nanoplastics. In addition, Raman spectroscopy and microscopy imaging were used to further confirm the presence and locations of nanoplastics on the electrode surface. This study highlights the combination of electrophoresis and QCM effectiveness in detecting nanoplastics across different water types and their potential for broader applications in environmental monitoring.

Integrated dual-biomarker detection: Transforming proteins and nucleic acids into ssDNA for enhanced disease diagnosis

Integrating information from protein and nucleic acid biomarkers enhances detection sensitivity and specificity, offering valuable insights for disease management compared to single biomarkers alone. Thus, there is an increasing demand for a unified diagnostic approach by introducing an innovative assay that simultaneously detects protein and nucleic acid biomarkers within a single test. Here we developed a method that uniquely transforms both protein and nucleic acid markers into single-stranded DNAs (ssDNAs), utilizing a novel combination of aptamers and the CRISPR/Cas9 system. Subsequent amplification of these ssDNAs through both linear and exponential rolling circle amplification enables simultaneous and efficient detection. This approach not only simplifies the diagnostic process but also conserves valuable sample volume, reduces the time required for detection, and minimizes the consumption of reagents and the need for extensive instrumentation. In a critical proof-of-concept application, we employed this assay to detect programmed cell death-ligand 1 (PD-L1) protein and epidermal growth factor receptor (EGFR) L858R circulating tumor DNA (ctDNA) in plasma of patients with non-small cell lung cancer (NSCLC), which helps to guide the selection of the most appropriate treatment for NSCLC patients, whether immunotherapy (based on PD-L1 expression) or targeted therapy (based on EGFR mutation). The remarkable results demonstrated high sensitivity (83.3% for EGFR L858R ctDNA and 88.2% for PD-L1) and specificity (100% for EGFR L858R ctDNA and 87.5% for PD-L1). These findings not only validate the effectiveness of our method but also underscore its potential as a transformative tool in the simultaneous monitoring of multiple types of biomarkers, paving the way for more nuanced and effective disease management strategies.

Nano-fuels-driven self-sacrificed ZIF-8@Apt integrated chip coupled with a DNAzyme system for the isolation and detection of glioblastoma-derived extracellular vesicles

Plasma extracellular vesicles (EVs) have emerged as promising biomarkers for the early diagnosis of glioblastoma. However, rapid and efficient isolation and detection of tumor-specific EV subsets from plasma remains challenging. To address this, we developed an innovative integrated chip based on self-sacrificial metal–organic frameworks and the epidermal growth factor receptor (EGFR) aptamers called ZIF-8@EGFR aptamer (ZIF-8@Apt), which further coupled with a “nano-fuels”-driven DNAzyme amplification strategy. The core functionality of the constructed chip lies in its ability to capture EVs with the ZIF-8@Apt module. Once captured, numerous DNA “nano-fuel” structures are in situ assembled on the EVs’ surfaces. Subsequently, the ZIF-8@Apt@EV@nano-fuels composites are lysed to release Zn2+, the EVs’ nucleic acids, and additional nano-fuels for subsequent detection. Finally, a DNAzyme detection system is introduced, where the released nano-fuels activate the DNAzyme, leading to multiple signal amplification aided by Zn2+ for highly sensitive detection of plasma EVs. This integrated approach effectively enriches and detects target EVs, achieving a significantly enhanced detection sensitivity of 500 particles/μL. In a clinical study involving glioblastoma patients, our chip demonstrated a remarkable ability to distinguish between cancer patients and healthy individuals, achieving an area under the curve (AUC) of 0.958. Moreover, the response signals of the chip can be conveniently read using fluorescence spectroscopy or microscope, offering a rapid, highly sensitive, and high-throughput analysis of plasma EVs for various application scenarios. Overall, this study introduces a comprehensive approach for the rapid isolation and accurate analysis of plasma EVs, holding significant promise for early diagnosis and disease monitoring.

Controllable Ultrathin Nickel Nanoislands With Dense Discrete Space Charge Regions: Steering Hole Extraction for High-Performance Underwater Multispectral Weak-Light Photodetection.

Undersea optical communication (UOC) is vital for ocean exploration and military applications. In the dim-light underwater environment, photodetectors must maximize photon utilization by minimizing optical losses and carrier recombination. This can be achieved by integrating ultrathin metal nanostructures with photocatalysts to form Schottky junctions, which enhance charge separation and injection while mitigating metal-induced light shading. The strategic design of discrete metal nanostructures providing numerous high-depth space charge regions (SCRs) without overlap offers a promising approach to optimize hole transport paths and further suppress recombination. Here, a facile phase-separation lithography technique is explored to fabricate tunable ultrathin Ni nanoislands atop n-Si, yielding high-performance photoelectrochemical photodetectors (PEC PDs) tailored for underwater weak-light environments. This results indicate that key determinant of hole extraction behavior is the relationship between the spacing distance of adjacent Ni nanostructures (ds) and twice the SCR radius (Ws). PEC PDs with optimized 8nm ultrathin Ni nanostructures featuring closely but non-overlapping SCRs, exhibit a 55-fold increase in photoresponsivity (2.2mAW-1) and a 128-fold enhancement in detection sensitivity (3.2 × 1011 Jones) at 0V over Ni film, revealing the exceptional stability. Furthermore, this approach enables effective detection across UV-vis-near infrared spectrum, supporting reliable multispectral UOC and underwater imaging capabilities.

Synthesis of 2MP-CuNPs Fluorescent Probes and Their Application in Tetracycline Detection.

A fluorescent probe composed of 2-mercaptopyridine-copper nanoparticles (2MP-CuNPs) was synthesized through a hydrothermal method utilizing CuCl2 and 2-mercaptopyridine (2MP). The experimental results indicate that the 2MP-CuNPs probe exhibited an excellent fluorescence emission peak at 525 nm with an excitation wavelength of 200 nm. Furthermore, this emission peak was accompanied by a substantial Stokes shift of 325 nm, which effectively minimized the overlap between the excitation and emission spectra, thereby enhancing detection sensitivity. In tetracycline (TC) detection, the dimethylamino group on TC undergoes protonation in acidic conditions, resulting in a H+ ion. Consequently, the nitrogen atom within the pyridine moiety of the 2MP-CuNPs probe forms a coordination complex with H+ via multi-toothed n-bonding interactions, leading to a significant reduction in fluorescence intensity at 525 nm. Based on this mechanism, a quantitative detection method for TC was successfully established with a linear range spanning from 0.1 to 240 µM and an impressive detection limit of 120 nM. Furthermore, during actual sample analyses involving milk and chicken feed, this analysis method based on the 2MP-CuNPs probe achieved absolute recovery rates ranging from 94% to 98%, underscoring its considerable potential for practical applications.

Water-Soluble Bimodal Magnetic-Fluorescent Radical Dendrimers as Potential MRI-FI Imaging Probes.

Dual or multimodal imaging probes have become potent tools for enhancing detection sensitivity and accuracy in disease diagnosis. In this context, we present a bimodal imaging dendrimer-based structure that integrates magnetic and fluorescent imaging probes for potential applications in magnetic resonance imaging and fluorescence imaging. It stands out as one of the rare examples where bimodal imaging probes use organic radicals as the magnetic source, despite their tendency to entirely quench fluorophore fluorescence. Opting for organic radicals over metal-based contrast agents like gadolinium (Gd3+)-chelates is crucial to mitigate associated toxicity concerns. We utilized an amino-terminated polyamide dendrimer containing a 1,8-naphthalimide (Naft) fluorescent group, amino acid derivatives as linkers to enhance water solubility, and TEMPO organic radicals as terminal groups. The same dendrimer structure, featuring an equivalent number of branches but lacking the fluorophore group, was also functionalized with amino acid and terminal radicals to serve as a reference. Remarkably, we achieved a fully water-soluble dendrimer-based structure exhibiting both magnetic and fluorescent properties simultaneously. The fluorescence of the Naft group in the final structure is somewhat quenched by the organic radicals, likely due to photoinduced electron transfer with the nitroxyl radical acting as an electron acceptor, which has been supported by density functional theory calculations. Molecular dynamics simulations are employed to investigate how the dendrimers' structure influences the electron paramagnetic resonance characteristics, relaxivity, and fluorescence. In summary, despite the influence of the radicals-fluorophore interactions on fluorescence, this bimodal dendrimer demonstrates significant fluorescent properties and effective r1 relaxivity of 1.3 mM-1 s-1. These properties have proven effective in staining the live mesenchymal stem cells without affecting the cell nucleus.

Exploring the role of graphene-metal hybrid nanomaterials as Raman signal enhancers in early stage cancer detection

Molecular diagnosis plays a significant role in detection of biomolecules linked to early stage cancer since it offers greater sensitivity and reliability for identification of biomarker level changes as the disease progresses. The application of vibrational spectroscopy in biomarker detection is defined by the fingerprint spectrum of a molecule originating from single-molecule vibrations. This characteristic makes surface enhanced Raman spectroscopy (SERS) a promising tool for identification of biomarkers. The performance of the SERS technique largely depends on the material being used as the SERS substrate. Graphene, with its large surface area and abundance of aromatic regions, is considered advantageous as SERS substrate. Combining graphene with metal nanomaterials considerably increases SERS signal intensity, thereby enhancing detection sensitivity. Therefore, this review emphasizes the significance of selecting graphene-metal nanohybrids as suitable SERS substrates for signal amplification. The detail understanding of the mechanism of graphene-metal hybrid in SERS based detection of early stage cancer is also presented. Furthermore, several examples demonstrated the application of graphene-metal hybrid nanomaterials in detecting biomarkers and cancer cell differentiation using SERS imaging.

Biocompatible Flash Chemiluminescent Assay Enabled by Sterically Hindered Spiro-Strained-Oxetanyl-1,2-Dioxetane.

Chemiluminescence is the emission of light that occurs as a result of a chemical reaction. Depending on the rate of chemiexcitation, light emission can occur as a long-lasting, low-intensity, glow-type reaction or a rapid, highly intense flash-type reaction. Assays using a flash-type mode of action provide enhanced detection sensitivity compared to those using a glow-type mode. Recently, our group discovered that applying spiro-strain to 1,2-dioxetanes significantly increases their chemiexcitation rate, thereby transforming glow-type chemiluminescence into flash-type chemiluminescence. However, further examination of the structure-activity relationships revealed that the spiro-strain severely compromises the chemical stability of the 1,2-dioxetanes. We hypothesized that a combination of spiro-strain, steric hindrance, and an electron-withdrawing effect, will result in a chemically stable spiro-strained dioxetane with an accelerated chemiexcitation rate. Indeed, spiro-fused tetramethyl-oxetanyl exhibited a 128-fold faster chemiexcitation rate compared to adamantyl while maintaining similar chemical stability, with a half-life of over 400 hours in PBS 7.4 buffer at room temperature. Turn-on probes composed of tetramethyl-oxetanyl spiro-dioxetane exhibited significantly improved chemical stability in bacterial and mammalian cell media compared to previously developed dioxetane probes fused to a cyclobutyl unit. The superior chemical stability enables a tetramethyl-oxetanyl dioxetane probe to detect β-Galactosidase (β-gal) activity with enhanced sensitivity in Escherichia coli (E. coli) bacterial assays and leucine aminopeptidase activity in tumoral cell lines. Overall, the development of the tetramethyl-oxetanyl dioxetane luminophore enables us to enhance the detection sensitivity of chemiluminescent probes while maintaining high chemical stability. The results obtained in this study should assist in designing improved chemiluminescent probes and underscore the significance of strain-release techniques in enhancing the detection sensitivity of chemiluminescence assays.

In Situ Construction of Polypyrrole–Silver Composite Conductive Phase in High‐Performance Polyimide Sponge and Study of Sensing Behavior Under Microstress

Composites comprising conductive polymers and metal particles have garnered considerable interest in sensor technology due to their excellent electrical conductivity. However, producing controllable pressure sensors that retain high sensitivity under microstress remains challenging. Polyimide (PI) sponge exhibits excellent chemical and thermal stability and a porous structure that facilitates considerable deformation under low stress levels and results in good sensitivity to external forces. Herein, a conductive polymer–metal composite conductive phase, polypyrrole–silver (PPy–Ag), is directly fabricated on the PI surface through incipient network conformal growth. This method ensures that the PPy–Ag composite maintains optimal performance within its original temperature range, thereby enhancing detection sensitivity at low stress levels. The maximum conductivity of the fabricated PPy–Ag/PI composite sponge‐based flexible piezoresistive sensor is 2.42 × 10−4 S m−1, and the sensitivity is recorded at 16.31 kPa−1 within a stress range of 0–80 Pa. After undergoing 1000 compression cycles, the sensor exhibits commendable stability and reproducibility.

Development of an Improved Thiosulfate-Utilizing Denitrifying Bacteria-Based Ecotoxicity Test with High Detection Sensitivity and Reproducibility.

Microorganism-based ecotoxicity assessment has been widely used as a reliable tool showing direct biochemical impacts of contaminants on ecosystems and the environment. The present study aimed at developing a thiosulfate-utilizing denitrifying bacteria (TUDB)-based ecotoxicity test with high detection sensitivity and favorable reproducibility. To achieve this goal, existing TUDB toxicity tests were improved by employing a pure culture of Thiobacillus thioparus ATCC 8158 and optimizing test conditions, particularly in terms of inoculated microbial biomass, incubating temperature, and operational pH. From control tests, it was found that 4 h is a sufficient processing time for TUDB test kits. As a result of optimization, 20 mg VSS/L of initial bacterial biomass, 25 °C of incubating temperature, and 6 of operational pH were determined as the most favorable test conditions, providing enhanced detection sensitivity and reproducibility. Under these optimal test conditions, I conducted toxicity tests for diverse toxic metals and obtained 0.65 ± 0.03, 1.09 ± 0.04, 1.21 ± 0.07, 0.13 ± 0.01, 0.56 ± 0.04, 1.42 ± 0.03, 0.98 ± 0.02, and 2.12 ± 0.05 mg/L of 4 h EC50 values for Ag+, As3+, Cd2+, Cr6+, Cu2+, Hg2+, Ni2+, and Pb2+, respectively. These EC50 values are substantially lower than those from earlier TUDB tests, demonstrating the high detection sensitivity of the current TUDB tests. Moreover, the present TUDB tests attained very low coefficient of variation (CV) values (1.6-6.3%) for the EC50, showing favorable reproducibility of the test methodology. In addition, the current TUDB toxicity tests offer numerous advantages for ecotoxicity assessment, including versatility for diverse test samples, no requirement for advanced equipment, and no distortion of end-point measurement. These refinements render the TUDB tests a favorable ecotoxicity assessment with enhanced sensitivity and reproducibility.

Distance-Based Fluorescent Immunosensor for Point-of-Care Test of Illegal Additives through the Gas-Producing Nanozyme.

The colorimetric point-of-care test (POCT) offers a rapid and efficient method for detecting specific targets in real samples. However, traditional colorimetric methods often rely on complex signal amplification techniques or electronic devices to enhance detection sensitivity, which can inadvertently increase both cost and time, thus contradicting the fundamental goals of visual detection methods. Here, we presented a distance-based fluorescent immunosensor that utilized a gas-producing nanozyme for continuous gas production reaction as a signal. Specifically, the SOM-ZIF-8@Pt nanozyme catalyzed the production of O2 from H2O2 to cause an obvious increase in the pressure within a sealed chamber, thus driving the production of H2S to quench the fluorescence of CsPbBr3 on the walls of the capillaries. Based on the competitive immunoassay, the fluorescence quenching lengths were relative with the concentration of aminopyrine in the range from 0.2 to 20 ng/L; thus, the fluorescent POCT-based homemade device was realized through the amplification of distance-based signals facilitated by the continuous gas production reaction. This strategy provides an effective way to realize POCT assays in resource-limited areas by transforming pressure variations into directly observable signals. Furthermore, distinguished by its high sensitivity, ease of operation, and portability, it also represents a significant advancement in biomedical diagnostics, particularly within home healthcare and clinical POCT.

Synergistic signal amplification for HER2 biosensing using tetrahedral DNA nanostructures and 2D transition metal carbon/nitride@Au composites via ARGET ATRP

The rising incidence of breast cancer underscores the critical need for accurate and early detection methods, particularly for key biomarkers like human epidermal growth factor receptor 2 (HER2). Here, a synergistic signal amplification electrochemical biosensor was developed for HER2 detection that utilizes tetrahedral DNA nanostructures (TDN), 2D transition metal carbon/nitride@Au (MXene@Au) composites, and activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP). Specifically, TDN serves as the substrate, with the aptamer anchored by the MXene@Au composite support matrix. This design facilitates the generation of electrochemical currents through the ARGET ATRP signal amplification strategy. The robustness and high affinity of TDN minimize surface effects on the electrode and enhance target binding. Additionally, the high conductivity of the MXene@Au composites improves the detection sensitivity of the biosensor. The use of the ARGET ATRP strategy further enhances detection sensitivity. The biosensor exhibits a wide detection range from 10 pg·mL−1 to 10 µg·mL−1 with a remarkable detection limit of 0.39 pg·mL−1, verified under optimal experimental conditions. The designed biosensor offers a significant advancement in the field of oncological diagnostics, providing a highly sensitive, low-cost, and simple method for early HER2 detection, thereby potentially improving treatment outcomes for breast cancer patients.

Tailoring glassy carbon electrode surface with FeBiO3 for electrochemical detection of dinitrophenol isomers

ABSTRACT This study presents a simultaneous, rapid, and highly sensitive electrochemical detection of 2,4- and 2,5-dinitrophenol isomers using an iron bismuth oxide (FeBiO3)-modified glassy carbon electrode (GCE). The FeBiO3-modified GCE exhibited superior electrochemical performance over bare GCE, Bi2O3-modified GCE, and Fe2O3-modified GCE, as demonstrated by electrochemical impedance spectroscopy (EIS) with the potassium ferricyanide (Fe(CN6)3-/4-) standard. The synthesised electrocatalyst FeBiO3 exhibited strong absorption both in the visible and UV regions of the spectrum, attributed to band gap transitions and charge transfer transitions linked to its Bi2O3 and Fe2O3 components. The morphology and the structure of the FeBiO3 were characterised using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD), while Fourier transform infrared spectroscopy (FTIR) was employed to analyse the functional groups attached to the surface of FeBiO3. Cyclic voltammetry (CV) clearly demonstrated an increased current and improved peak resolution for the reduction of 2,4- and 2,5-dinitrophenols at the FeBiO3/GCE, compared to the bare GCE. The mechanism shows that the reduction of 2,4- and 2,5-dinitrophenols occurs through interactions with the surface oxygen functional groups of FeBiO3, resulting in the stepwise reduction of their NO2 groups to hydroxyamino compounds and then to nitrosophenols. Using square wave voltammetry (SWV), the reduction peak currents were significantly improved, enhancing detection sensitivity beyond that reported in previous works. A linear range from 1 µM to 1 mm for the dinitrophenol isomers was established, with detection limits of 0.07 µM for 2,4-dinitrophenol and 0.09 µM for 2,5-dinitrophenol. The FeBiO3/GCE electrode showed interferences with mono-nitrophenols and mono-/di-chlorophenols in solution but maintained excellent long-term stability and reproducibility, allowing it to effectively detect dinitrophenol isomers in drinking water, tap water, and wastewater samples.

DNA Origami Incorporated into Solid-State Nanopores Enables Enhanced Sensitivity for Precise Analysis of Protein Translocations.

The rapidly advancing field of nanotechnology is driving the development of precise sensing methods at the nanoscale, with solid-state nanopores emerging as promising tools for biomolecular sensing. This study investigates the increased sensitivity of solid-state nanopores achieved by integrating DNA origami structures, leading to the improved analysis of protein translocations. Using holo human serum transferrin (holo-hSTf) as a model protein, we compared hybrid nanopores incorporating DNA origami with open solid-state nanopores. Results show a significant enhancement in holo-hSTf detection sensitivity with DNA origami integration, suggesting a unique role of DNA interactions beyond confinement. This approach holds potential for ultrasensitive protein detection in biosensing applications, offering advancements in biomedical research and diagnostic tool development for diseases with low-abundance protein biomarkers. Further exploration of origami designs and nanopore configurations promises even greater sensitivity and versatility in the detection of a wider range of proteins, paving the way for advanced biosensing technologies.