A single-pot electrochemical sensing platform that enables rapid and ultrasensitive quantitative detection of AD biomarkers directly from untreated blood or plasma within 20 min of collection, without sample preparation, washing, or using additional reagents is reported.
Abstract
Blood-based biomarkers have great potential for the early diagnosis of Alzheimer’s disease (AD); however, their implementation in primary healthcare screening remains largely limited owing to their reliance on sophisticated instruments and complex procedures. Furthermore, the complexity of the biological matrix poses a significant challenge to detection without washing and the use of reagents. Herein, we report a single-pot electrochemical sensing platform that enables rapid and ultrasensitive quantitative detection of AD biomarkers directly from untreated blood or plasma within 20 min of collection, without sample preparation, washing, or using additional reagents. This platform integrated high-affinity antibodies with an electric field-driven sensing mechanism based on a molecular pendulum. Upon the application of a potential, a negatively charged DNA scaffold moved directionally toward the electrode, enabling the real-time dynamic detection of surface-confined redox reporters and precise biomarker quantification. We validated the platform in 80 clinical plasma samples using Aβ42 and p-tau217 as representative biomarkers. We found that combined biomarker analysis outperformed single-analyte detection and achieved an area under the curve of 0.9475, with 82.5% sensitivity and 92.5% specificity. This work establishes a truly wash-free and reagentless electrochemical sensing strategy, showing great potential for early diagnosis of AD in community or home settings.
Alzheimer's disease (AD) is a progressive neurodegenerative disorder requiring early diagnosis for effective intervention. The combination of blood Aβ42/Aβ40 ratio and p-tau-181 is recognized as a promising core biomarker panel for AD diagnosis. However, conventional detection methods suffer from limitations including time-consuming procedures, lack of multiplexing capability, and insufficient sensitivity. Herein, we developed a magnetic surface-enhanced Raman scattering (SERS)-encoded tags-based lateral flow immunoassay (LFIA) for simultaneous detection of Aβ42, Aβ40, and p-tau-181 on a single test line. Magnetic Fe3O4@Au nanoparticles were synthesized and modified with three distinct Raman reporters (DTNB for Aβ42, 4-MBA for Aβ40, and 2-MPY for p-tau-181) and corresponding detection antibodies. Under optimal conditions, the assay achieved rapid detection (∼28 min) and high sensitivity, with limits of detection of 93.33 fg/mL for Aβ42, 218.78 fg/mL for Aβ40, and 56.23 fg/mL for p-tau-181. The method exhibited excellent specificity against interfering substances (BSA, human IgG) and closely related species (Aβ38, p-tau-217), as well as good reproducibility (RSD <5%) and stability (≥4 weeks). In clinical plasma samples (n = 40), the combined score (p-tau-181/(Aβ42/Aβ40)) progressively increased with disease severity and correlated well with MMSE scores and MRI MTA grades, capturing both cognitive decline and hippocampal atrophy. This magnetic SERS-encoded LFIA platform offers a rapid, sensitive, user-friendly, and multiplex-capable approach for early AD diagnosis and progression monitoring, showing promise for future point-of-care applications.
Min Peng, Lei Shao, Jiangkun Zhai et al.· Talanta: The International J...· 0 citations
Differentiating overlapping dementia pathologies, such as frontotemporal dementia and Alzheimer’s disease, calls for the simultaneous measurement of several blood biomarkers, yet electrochemical sensors remain predominantly single-target and dependent on labels and sample preparation. Here we report SMART-NeuroDx, a reagent-free electrochemical array that quantifies pTau217, GFAP, pTau181, and NfL directly from unprocessed plasma and serum in under 35 minutes. Four surface-confined redox-active molecularly imprinted polymer and aptamer-MIP recognition matrices are electropolymerized onto a four-working-electrode porous-gold printed-circuit array, using potential-assisted electrostatic gating keyed to each target’s isoelectric point to prevent cross-channel template contamination during synthesis. Label-free Faradaic responses from the redox-active polymer backbone are acquired on a custom battery-powered STM32G4 handheld potentiostat and converted to concentration from five voltammetric features using cross-validated Random Forest and XGBoost regressors. The handheld unit reproduced the baseline fidelity of a commercial benchtop workstation and resolved sub-picogram pTau217 (limit of detection 0.087 pg mL⁻¹) across marker-appropriate dynamic ranges, with inter-chip relative standard deviation at or below 5.34% and coefficients of determination of 0.94 to 0.99 against reference concentrations. Each channel retained selectivity in plasma and serum against competing neurological and inflammatory proteins, with non-specific signal deviation held below 10% by the hydrated PyPEG interfacial shell. The platform establishes reagent-free, simultaneous four-analyte neurodegeneration sensing on a single point-of-care device.
S. Deshpande, Krzysztof Pawlak, M. Prathap et al.· bioRxiv· 0 citations
Early diagnosis of Alzheimer’s disease (AD) can facilitate the establishment and implementation of therapeutic interventions. The currently used diagnosis methods for AD mainly include cerebrospinal fluid analysis and positron emission tomography imaging. Due to their high invasiveness, high cost, and limited accessibility, these technologies are difficult to meet the needs of large-scale population screening, grading diagnosis, and treatment, thereby limiting the popularization of early diagnosis of AD. The detection of blood biomarkers has become an important breakthrough in early screening and diagnosis of different diseases due to its non-invasive, low-cost, and easy-to-operation advantages. Recently, blood proteins such as amyloid-beta (Aβ), total and phosphorylated Tau, light chain neurofilaments (NFL), and glial fibrillary acidic protein (GFAP) have been considered promising biomarkers for the diagnosis of AD. However, there is currently no effective, minimally invasive, and easily accessible detection method for clinical diagnosis and risk prediction of AD. Electrochemical and electrical biosensors are highly sensitive, simple, fast, and cost-effective analytical tools for disease monitoring, drug development, and target detection. In this work, we comprehensively and systematically overview the progress of various electrochemical and electrical techniques for determining AD-related blood protein biomarkers, mainly including electrochemistry, electrochemiluminescence, photoelectrochemistry, quartz crystal microbalance, field-effect transistor, and organic electrochemical transistor. This work can provide guidance for researchers to develop novel electrochemical and electrical biosensors for early and accurate diagnosis of AD.
Fengli Gao, Lin Liu, Jun-Yue Li et al.· Biosensors· 0 citations
Alzheimer’s disease (AD) is a progressive neurodegenerative disorder characterized by the accumulation of amyloid-beta (Aβ) plaques in the brain. Recent clinical studies indicate that the ratio of Aβ42 to Aβ40 in blood plasma is a more reliable biomarker for early AD screening than individual peptide concentrations, as it reflects the brain's Aβ sequestration. However, detecting these biomarkers in blood remains challenging due to their ultra-low abundance and the structural similarity between Aβ42 and Aβ40.
In this work, we developed an electrochemical biosensor using laser-induced graphene (LIG) electrodes, fabricated via one-step CO
2
laser scribing on polyimide. To optimize the interface for antibody immobilization, a low-damage plasma treatment (LDPT) was strategically employed to introduce nitrogen-containing functional groups (e.g., amine groups) onto the LIG surface. This plasma-assisted modification creates highly reactive sites that facilitate the stable and high-density covalent bonding of specific Aβ42 and Aβ40 antibodies via their carboxyl groups, ensuring a robust bio-interface without compromising the structural integrity of the graphene lattice. The resulting LIG-based biosensors demonstrated exceptional sensitivity, achieving a limit of detection (LOD) at sub-picomolar concentrations. To validate the clinical diagnostic potential, we examined the sensor's specificity by preparing a series of samples with predefined Aβ42/Aβ40 concentration ratios. These samples were tested on Aβ42 and Aβ40-antibody-modified sensors, respectively. The results indicated that the detected concentration ratios were highly consistent with the known concentrations, confirming the platform's high fidelity and cross-reactivity resistance for the precise determination of the Aβ42 to Aβ40 ratio in complex analytical scenarios.
By leveraging LDPT for surface functionalization, we have developed a robust and sensitive LIG-based electrochemical biosensing platform of electrochemical biosensors. This approach provides a scalable and cost-effective solution for the simultaneous detection of Aβ biomarkers, supporting the development of portable point-of-care devices for early Alzheimer’s intervention.
Alzheimer’s disease (AD) is the most common neurodegenerative disorder worldwide. Early diagnosis of AD is crucial for delaying disease progression and improving patients’ quality of life. Blood biomarkers, particularly amyloid-beta (Aβ) and Tau proteins along with their phosphorylated isoforms, show advantages such as convenient sampling, minimal invasiveness, and excellent repeatability. However, the extremely low concentrations of AD biomarkers in blood impose stringent requirements on the sensitivity, specificity, and anti-interference capability of detection methods. Optical methods provide promising analytical platforms to address these challenges in view of their intrinsic merits of high sensitivity and selectivity; rapid response; and potential for miniaturization. This review systematically summarizes the latest advances in optical methods for the detection of the two core AD blood biomarkers (Aβ and Tau), covering techniques such as colorimetry, fluorescence, chemiluminescence, surface plasmon resonance (SPR), and surface-enhanced Raman scattering (SERS). The sensing principles, design strategies, and analytical performances of these methods are discussed, with special emphasis on different signal amplification strategies. In addition, several challenges and future prospects are provided with a primary focus on single-molecule detection, insufficient sensitivity and stability, lack of validation with large clinical cohorts, and absence of standardization. This review aims to provide researchers with guidance for the rational development of high-performance optical methods to achieve early diagnosis of AD.
Ning Xia, Fengli Gao, Chu-Ye Zheng· Biosensors· 0 citations
Neuroinflammation plays a major role in the development of numerous neurological disorders, yet conventional immunoassays are restricted by large sample volume requirements, limited multiplexing capability and insufficient analytical sensitivity.
To develop and evaluate a continuous, low-volume and high-performance diagnostic platform for multiplex neuroinflammatory biomarker detection.
A countercurrent microfluidic immunoaffinity platform was developed incorporating antibody-functionalised serpentine microchannels, nanocomposite-based electrochemical immunosensors and real-time computational analysis. Antigen–antibody interaction was enhanced by countercurrent laminar flow, while enzymatic redox amplification enabled ultrasensitive electrochemical quantification.
The system achieved a capture efficiency of 89.2%, representing a 2.3-fold improvement over single-pass flow and an enrichment factor of 18.4 for interleukin-6 in cerebrospinal fluid (CSF). Electrochemical detection reached a limit of detection of 0.05 pg/mL, providing approximately 40-fold higher sensitivity than the enzyme-linked immunosorbent assay (ELISA) with strong linearity (
R
> 0.99). Clinical CSF samples demonstrated successful multiplexed detection of 12 biomarkers, all with coefficients of variation < 8% and strong correlation with ELISA (
R
= 0.91–0.98). The technology achieved 92.3% accuracy in identifying neuroinflammatory disease subtypes while reducing sample volume ten-fold and total assay time to 22 min.
This countercurrent microfluidic immunoaffinity platform offers a low-volume, high-sensitivity and clinically feasible method for multiplex neuroinflammatory biomarker detection. Its integration of continuous-flow enrichment with advanced electrochemical sensing positions it as a promising next-generation diagnostic tool for point-of-care neurological assessment.
S. Alshahrani, Maya Saeed Baselim, Faisal Shuayl Alkathiri et al.· Journal of Advanced Trends i...· 0 citations
