Attomole Level Research Articles

Revealr-Based Diagnostic Panel for Rapid Detection of Acute Respiratory Infections.

RNA-encoded viral nucleic acid analyte reporter (REVEALR) is a rapid and highly sensitive point-of-care diagnostic developed for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) detection, genotyping, and quantification. Here, we extend the breadth of this nucleic acid technology to include a viral respiratory panel that can detect low attomolar levels of influenza A (IAV), influenza B (IBV), SARS-CoV-2 (CoV2), and the respiratory syncytial virus (RSV). Of 39 clinical samples collected at the UCI Medical Center in Orange, California, the extended REVEALR panel showed a positive predictive agreement and negative predictive agreement of 100% for IAV, CoV2, and RSV in sequence-verified clinical samples, with 0 false positive results. Additionally, REVEALR was able to detect a synthetic IBV genome and precisely identify the viruses from clinical samples that were combined to simulate a patient infected with more than one virus. Together, these results demonstrate that the REVEALR respiratory panel provides a valuable diagnostic for identifying the pathogens responsible for causing lower respiratory infections that pose serious healthcare challenges in the United States.

Spherical Nucleic Acid Probes on Floating-Gate Field-Effect Transistor Biosensors for Attomolar-Level Analyte Detection.

Field-effect transistor (FET) sensors are attractive for the label-free detection of target biomolecules, offering ultrahigh sensitivity and a rapid response. However, conventional methods for modifying biomolecular probes on sensors often involve intricate and time-consuming procedures that require specialized training. Herein, we propose a simple and versatile approach to functionalize floating-gate (FG) FET sensors by exploiting the strong binding ability of polyvalent interactions and the three-dimensional structure of densely functionalized spherical nucleic acids (SNAs). Crucially, the SNAs can be easily deposited onto a dielectric layer under mild conditions, ensuring stable immobilization of the probes. Further, the SNAs show efficient and robust immobilization on various dielectric layers including Y2O3, Ta2O5, and HfO2, forming conjugates that resist denaturation by various agents. By modifying the DNA sequence within the SNAs, we achieved highly sensitive FG-FET biosensors for DNA, adenosine triphosphate, and viral nucleic acids at the attomolar level. For clinical samples detection, unamplified enterovirus 71 RNA at levels as low as 0.13 copies μL-1 was detected within 100 s. Moreover, the sensor attained 100% accuracy for analyte detection in both positive and negative samples. Our findings provide a general and simple method for fabricating FET-based biochemical sensors and demonstrate that the SNA-modified FG-FET biosensor is a versatile and reliable integrated platform for ultrasensitive biomarker detection.

Attomolar sensitivity of a redox capacitive and DNA-receptive interface attained by quantum-rate signal amplification concept

This study demonstrates the application of quantum capacitance (Cq) methods to develop highly sensitive genosensors. This is achieved by employing the quantum mechanical rate (ν∝e2/hCq) concept to enhance the signal response of a redox-active, DNA-receptive interface. In these DNA-receptive interfaces, electrons are transported through the redox-tagged component, enabling signal amplification by adding a redox probe to the sample containing the target DNA. This is effective provided the formal potential of the added redox probe aligns with the energy state E=e2/Cq of the redox-tagged interface. This signal amplification methodology allowed us to detect attomolar levels of DNA biomarkers for diagnosing head and neck squamous cell carcinomas, where amplification is advantageous due to the typically low concentrations of target DNA in biological samples.Designed redox-tagged and DNA-receptive interfaces exhibited a broad detection range, from 103 aM to 108 aM (without amplification) and 1 aM to 105 aM (with amplification), with limit-of-detections ranging from 1.5 fM (without amplification) to 2.2 aM (with amplification). This demonstrates the attomolar sensitivity of this quantum-mechanical signal amplification method for label-free and early clinical diagnosis of cancer, using a genomic receptive interface fabricated through well-established self-assembled monolayer approaches.

Precise Genotyping Via Surface‐Enhanced Raman Spectroscopy‐Based Optical Sensing Chip for Guiding Targeted Therapy in Lung Cancer

AbstractThe emergence of “precision medicine” marks a notable shift in cancer treatment, moving from a tumor type–oriented approach to a more targeted, gene‐oriented approach. Detecting low‐abundance mutant genes in blood is challenging but crucial for personalized treatment plans. Herein, a novel platform combining catalytic hairpin self‐assembly (CHA)‐mediated self‐calibrating surface‐enhanced Raman spectroscopy (SERS) with a high‐throughput Raman system (CCSPS) was designed. This platform enables ultrasensitive and rapid genotype analysis of gene mutations. The development of CCSPS specifically targets EGFR mutations, which serve as crucial therapeutic targets for precision therapy in lung cancer. This system shows excellent sensitivity and selectivity, capable of detecting multiple EGFR mutations (Del‐19, L858R, and T790M) with a detection limit as low as attomolar levels. Additionally, precise genotyping analysis was successfully conducted on 42 clinical samples using the CCSPS, yielding results consistent with those obtained through next‐generation sequencing. These results underscore the efficacy of the CCSPS in noninvasively identifying circulating tumor DNA (ctDNA) mutations, facilitating immediate therapeutic decision making at the bedside. In summary, the CCSPS is a fast, accurate, versatile, and compact testing system capable of precisely screening individuals who stand to benefit from targeted therapy, thus promoting personalized and precise healthcare.

Development of a Recombinase Polymerase Amplification-Coupled CRISPR/Cas12a Platform for Rapid Detection of Antimicrobial-Resistant Genes in Carbapenem-Resistant Enterobacterales.

The worldwide spread of carbapenemase-producing Enterobacterales (CPE) represents a significant threat owing to the high mortality and morbidity rates. Traditional diagnostic methods are often too slow and complex for rapid point-of-care testing. Therefore, we developed a recombinase polymerase amplification (RPA)-coupled CRISPR/Cas12a system (RCCS), a rapid, accurate, and simple diagnostic platform for detecting antimicrobial-resistant genes. The RCCS detected carbapenemase genes (blaKPC and blaNDM) within 50 min, including 10 min for DNA extraction and 30-40 min for RCCS reaction (a 20 min RPA reaction with a 10-20-min CRISPR/Cas12a assay). Fluorescence signals obtained from the RCCS platform were visualized using lateral-flow test strips (LFSs) and real-time and endpoint fluorescence. The LFS clearly displayed test lines while detecting carbapenemase genes. Furthermore, the RCCS platform demonstrated high sensitivity by successfully detecting blaKPC and blaNDM at the attomolar and picomolar levels, respectively. The accuracy of the RCCS platform was validated with clinical isolates of Klebsiella pneumoniae and Escherichia coli; a 100% detection accuracy was achieved, which has not been reported when using conventional PCR. Overall, these findings indicate that the RCCS platform is a powerful tool for rapid and reliable detection of carbapenemase-encoding genes, with significant potential for implementation in point-of-care settings and resource-limited environments.

Early-stage Alzheimer’s disease profiling in blood achieved by multiplexing aptamer-SERS biosensors

Neurological disorders are the second leading cause of death globally, with Alzheimer’s disease (AD) emerging as a significant contributor, responsible for 276 million cases in disability-adjusted life years. Conventional diagnostic methods are often invasive, costly, and place a considerable strain on global healthcare systems. In this study, we presented an innovative and efficient strategy for AD assessment through blood profiling using a multiwell glass chip integrated with aptamer-based surface-enhanced Raman scattering (SERS) biosensors. High-affinity aptamers were selected using capillary electrophoresis-based systematic evolution of ligands by exponential enrichment (CE-SELEX). A mouse brain injury model was employed to systematically investigate biomarkers indicative of physiological, vascular, and cellular damage, such as neurogranin (Nrgn), angiopoietin-2 (Angio-2), PRDX3, lactate dehydrogenase (L-LDH), and τ-441, which were quantified at atto-molar levels in blood samples. Additionally, with the aid of CT-scan imaging, an aptamer-SERS assay was developed to evaluate the dynamic regulation of AD biomarkers. The aptamer-SERS biosensor system was also applied to human samples, demonstrating its capability to multiplex AD biomarkers and establish a time-dependent correlation between percentage biomarker regulation and disease progression. The innovative design, fabrication of aptamer-SERS nanoprobes, and the bio-sensing outcomes illustrate the strong potential of this approach for selective, sensitive, and quantitative early-stage AD diagnosis in clinical applications.

High-sensitivity label-free electrochemical genosensors for carbon nanotube plasmon-assisted detection of somatic mutations in nucleic acids from formalin-fixed paraffin-embedded tissues

Currently, molecular genetic testing of somatic point mutations in the genome of cancer tumors for targeted therapy requires high-performance tools for studies of spatial gene expression and spatial genome profiling in formalin-fixed paraffin-embedded (FFPE) tissue samples. We offer new high-performance label-free electrochemical impedimetric deoxyribonucleic-acid (DNA) nanosensors. The sensors based on a platform of crystalline carbon nanotube plasmonic assemblies are fabricated by the Langmuir–Blodgett deposition technique. The carbon-nanotube assemblies are suspended on nanoporous supports. Incorporation of fast Fourier transforms in the impedance spectroscopy led to the introduction of a new information parameter, the integral value of capacitance changes. The allele-sensitive assay based on plasmon-assisted effects in the assemblies of electrically active conjugates between DNA and few-walled carbon nanotubes has been used for discrimination of allele single-nucleotide polymorphisms (SNPs) of Kirsten Rat Sarcoma viral oncogene homologue (KRAS gene). Using 19- and 20-mer single-stranded (ss) probe oligonucleotides and 35- and 47-mer toehold probes, we explored the probe length and the target location. The genotyping technology allows discrimination of single-nucleotide variations in the target 35-base oligonucleotide at the attomolar concentration level. Human genomic DNAs were isolated from FFPE colorectal cancer tumor tissue samples. The KRAS-gene exon 2, codon 12, c.35G>A mutation has been successfully discriminated in the genomic DNAs with a significance level, P, of 0.001–0.02. The assay has a sensitivity with 0.33-ng/ml limit of detection (LOD) for native genomic DNA.

Ball-in-hole 3D nanoarchitectonics based on nanoporous Au film: Ultrasensitive, highly reliable, and reusable plasmonic platform

Hotspots have a locally enhanced electromagnetic field, effectively created by nanogaps in plasmonic metal nanostructures. The formation of uniform nanogaps, smaller than a few nanometers, allows for the detection of analytes at low concentrations and ensures reliable measurements across entire surface-enhanced Raman scattering (SERS) substrates. Despite the demand for SERS substrates in recent optical sensing applications, challenges remain in developing new techniques to maximize the number and optimize the size of nanogaps on large-area substrates. To address this issue, this study introduces a new ball-in-hole technique based on metal nanoarchitecture utilizing 3D nanoporous gold film (NPGF) and 0D gold nanoparticles (AuNPs). Using the ball-in-hole technique, 23 nm AuNPs are placed within the ∼ 28 nm mesopores of the metal film, creating uniform nanogaps of just a few nanometers that ensure consistent SERS signals across a large substrate area due to effective hotspots. The 23nmNP@NPGF substrate exhibited an enhancement factor (EF) of 1014 for 4-aminophenol (4-ATP), enabling detection at the attomole level. Moreover, the substrate retained its performance after five washing and reuse cycles, demonstrating excellent recyclability Finally, the substrate successfully detected femtomolar concentrations of key neurotransmitters like dopamine and glutamate, without requiring Raman reporters. This study presents a promising strategy for constructing metal nanoarchitectures with numerous hotspots, offering new possibilities for developing more efficient SERS substrates.

A Multiplexed Digital Platform Enables Detection of Attomolar Protein Levels with Minimal Cross-Reactivity.

Protein-based biomarkers are essential for disease diagnostics, yet their low abundance in biofluids often presents significant detection challenges for traditional enzyme-linked immunosorbent assay (ELISA) techniques. While various ultrasensitive methods such as digital ELISA have improved sensitivity, multiplex assays still suffer from considerable cross-reactivities that can compromise result accuracies. To address this challenge, we have developed barcoded Molecular On-bead Signal Amplification for Individual Counting (barcoded MOSAIC), a multiplexed digital ELISA technology that markedly reduces cross-reactivity by pairing barcoded detection antibodies with specific bead types. This approach enables the simultaneous detection of eight analytes from less than 9 μL of blood, with sensitivities ranging from midpicomolar to low-attomolar levels and a collective dynamic range exceeding seven logs across multiple analytes within a single multiplex assay. Additionally, barcoded MOSAIC is compatible with standard immunoassay reagents and workflows, utilizing a rapid, automatable flow cytometric readout for quantification, which makes it a highly accessible benchtop platform that is readily adoptable by both research and clinical laboratories, setting the stage for future translation into point-of-care applications.

Quantitative Analysis of Cell-Free RNA at Attomolar Level Using CRISPR/Cas Digital Imaging Platform.

Quantitative analysis of cell-free RNA (cfRNA) in plasma sample can be used for screening, diagnosing, and prognosticating of multiple diseases. Here, we report a quantitative CRISPR/Cas digital imaging platform (qCasdip) for the detection of various cfRNAs, including circular RNAs and miRNAs, in clinical samples at the attomolar (aM) level without the need for preamplification. Digital counting strategy provides qCasdip quantitative ability with a linear detection range of 102-106 aM. Meanwhile, qCasdip demonstrated cfRNA profiling in clinical plasma samples, improving the diagnosis of breast cancer. These data highlight the potential of qCasdip to quantitatively assess the molecular patterns of specific cfRNA panels in plasma, thereby providing a novel liquid biopsy solution to enhance disease diagnosis.

Development of ultrasensitive genosensor targeting pathogenic Leptospira DNA detection in artificial urine

In the last decades, to access the stages of leptospirosis pathogenicity, site of infection, progression, monitor disease, and after-treatment were required especially non-invasive techniques. This becomes one of the significant goals for researchers. In this study, we developed a highly sensitive DNA-based electrochemical sensor to detect pathogenic leptospires in urine samples using a gold screen-printed electrode. The gold working electrode was electrodeposited with diazonium salt (CMA) with external carboxylic acid from the surface, and the specific Loa22 single-stranded DNA (ssDNA) probe to Leptospira interrogans was immobilized through a carbodiimide chemical reaction. The modified working electrode was characterized by contact angle measurement, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). After that, targeted DNA testing showed the EIS change in the range of 5 ag mL-1 - 16 fg mL-1 with a correlation R2 of 0.9638. The high sensitivity electrochemical sensor indicated a lower limit of detection to the attomolar level specifically 5 ag mL-1. Additionally, the developed genosensor exhibited high specificity without crossing other bacteria present in urine such as Escherichia coli, Staphylococcus aureus, and S. typhi as well as non-pathogenic leptospires L. biflexa serovar Patoc. Leptospires DNA was analyzed in both buffer solution and diluted artificial urine and detection in diluted artificial urine 1:1,000 was possible despite salt interferences. This study provides a highly sensitive lower detection platform for leptospirosis, offering potential for further development as a portable and point-of-care testing tool.

Enhanced CRISPR/Cas-Based Immunoassay through Magnetic Proximity Extension and Detection.

Clustered regularly interspaced short palindromic repeats (CRISPR)/Cas-associated systems have recently emerged as a focal point for developing next-generation molecular diagnosis, particularly for nucleic acid detection. However, the detection of proteins is equally critical across diverse applications in biology, medicine, and the food industry, especially for diagnosing and prognosing diseases like cancer, Alzheimer's and cardiovascular conditions. Despite recent efforts to adapt CRISPR/Cas systems for protein detection with immunoassays, these methods typically achieved sensitivity only in the femtomolar to picomolar range, underscoring the need for enhanced detection capabilities. To address this, we developed CRISPR-AMPED, an innovative CRISPR/Cas-based immunoassay enhanced by magnetic proximity extension and detection. This approach combines proximity extension assay (PEA) with magnetic beads that converts protein into DNA barcodes for quantification with effective washing steps to minimize non-specific binding and hybridization, therefore reducing background noise and increasing detection sensitivity. The resulting DNA barcodes are then detected through isothermal nucleic acid amplification testing (NAAT) using recombinase polymerase amplification (RPA) coupled with the CRISPR/Cas12a system, replacing the traditional PCR. This integration eliminates the need for thermocycling and bulky equipment, reduces amplification time, and provides simultaneous target and signal amplification, thereby significantly boosting detection sensitivity. CRISPR-AMPED achieves attomolar level sensitivity, surpassing ELISA by over three orders of magnitude and outperforming existing CRISPR/Cas-based detection systems. Additionally, our smartphone-based detection device demonstrates potential for point-of-care applications, and the digital format extends dynamic range and enhances quantitation precision. We believe CRISPR-AMPED represents a significant advancement in the field of protein detection.

Nanoparticle-Supported, Rapid, and Electronic Detection of SARS-CoV-2 Antibodies and Antigens at Attomolar Level.

A gold nanoparticle (AuNP)-supported rapid, electronic detection (NasRED) platform is demonstrated with high specificity to differentiate SARS-CoV-2 from human coronaviruses while achieving high sensitivity. Uniquely, active fluidic force is exerted on AuNPs in a microcentrifuge tube, through engineered centrifugation and vortex agitation, to accelerate signal transduction from biochemical protein binding to physical AuNP aggregation and precipitation and finally to electronic signals in a customized, stabilized circuitry. The limits of detection are found <80 aM (12 fg/mL) and ∼700 aM (105 fg/mL) to detect antibodies in human pooled serum and 20% diluted whole blood, and <900 aM (45 fg/mL) and 4.1 fM (200 fg/mL) to detect nucleocapsid proteins in human saliva and nasal fluid, respectively. With a small test volume (6 µL), a rapid turnaround time (as fast as <15 min), low reagent cost (estimated ∼$2), and a small system footprint, this novel digital platform can be utilized for accurate diagnosis and screening of a wide range of infectious and chronic diseases.

Ultrasensitive Raman Detection of Biomolecular Conformation at the Attomole Scale using Chiral Nanophotonics.

Understanding the function of a biomolecule hinges on its 3D conformation or secondary structure. Chirally sensitive, optically active techniques based on the differential absorption of UV-vis circularly polarized light excel at rapid characterisation of secondary structures. However, Raman spectroscopy, a powerful method for determining the structure of simple molecules, has limited capacity for structural analysis of biomolecules because of intrinsically weak optical activity, necessitating millimolar (mM) sample quantities. A breakthrough is presented for utilising Raman spectroscopy in ultrasensitive biomolecular conformation detection, surpassing conventional Raman optical activity by 15 orders of magnitude. This strategy combines chiral plasmonic metasurfaces with achiral molecular Raman reporters and enables the detection of different conformations (α-helix and random coil) of a model peptide (poly-L/D-lysine) at the ≤attomole level (monolayer). This exceptional sensitivity stems from the ability to detect local, molecular-scale changes in the electromagnetic (EM) environment of a chiral nanocavity induced by the presence of biomolecules using molecular Raman reporters. Further signal enhancement is achieved by incorporating achiral Au nanoparticles. The introduction of the nanoparticles creates highly localized regions of extreme optical chirality. This approach, which exploits Raman, a generic phenomenon, paves the way for next-generation technologies for the ultrasensitive detection of diverse biomolecular structures.

Quantification of HPV16 E7 Oncoproteins in Urine Specimens from Women with Cervical Intraepithelial Neoplasia.

We present the validity of using an ultrasensitive enzyme-linked immunosorbent assay (ELISA) for quantifying high-risk human papillomavirus (HPV) 16 E7 oncoproteins in urine specimens as a noninvasive method of analyzing the oncogenic activity of HPV. Some reports claim that the oncogenic activity of HPV is a more relevant clinical indicator than the presence of HPV DNA for estimating malignant potential. In the present study, urine containing HPV16 and related types were selected by uniplex E6/E7 polymerase chain reaction and classified according to the pathologic diagnosis of cervical intraepithelial neoplasia (CIN) in cervical biopsy specimens. Our ultrasensitive ELISA was able to detect attomole levels of HPV16 E7 oncoproteins, and it detected HPV16-positive SiHa cells at >500 cells/mL without detecting HPV18-positive cells. Our ELISA results showed E7 oncoproteins in 80% (4/5) of urine specimens from women with HPV16-positive CIN1, 71% (5/7) of urine specimens from CIN2 patients, and 38% (3/8) of urine specimens from CIN3 patients. Some urine specimens with undetectable E7 oncoproteins were thought to be negative for live HPV 16-positive cells or in an inactivated state of infection. These results provide the basis for assessing oncogenic activity by quantifying E7 oncoproteins in patient urine.

Ultrasensitive Detection Strategy of Norovirus Based on a Dual Enhancement Strategy: CRISPR-Responsive Self-Assembled SNA and Isothermal Amplification.

Spherical nucleic acids (SNAs) have been used to construct various nanobiosensors with gold nanoparticles (AuNPs) as nuclei. The SNAs play a critical role in biosensing due to their various physical and chemical properties, programmability, and specificity recognition ability. In this study, CRISPR-responsive self-assembled spherical nucleic acid (CRISPR-rsSNA) detection probes were constructed by conjugating fluorescein-labeled probes to the surface of AuNPs to improve the sensing performance. Also, the mechanism of ssDNA and the role of different fluorescent groups in the self-assembly process of CRISPR-rsSNA were explored. Then, CRISPR-rsSNA and reverse transcription-recombinase polymerase amplification (RT-RPA) were combined to develop an ultrasensitive fluorescence-detection strategy for norovirus. In the presence of the virus, the target RNA sequence of the virus was transformed and amplified by RT-RPA. The resulting dsDNA activated the trans-cleavage activity of CRISPR cas12a, resulting in disintegrating the outer nucleic acid structure of the CRISPR-rsSNA at a diffusible rate, which released reporter molecules. Norovirus was quantitated by fluorescence detection. This strategy facilitated the detection of the norovirus at the attomolar level. An RT-RPA kit for norovirus detected would be developed based on this method. The proposed method would be used for the detection of different viruses just by changing the target RNA and crRNA of the CRISPR cas12a system which provided a foundation for high-throughput detection of various substances.

Amplification-Free Digital Immunoassay down to the Attomolar Level by Synergistic Sedimentation of Brownian Motion Suppression and Dehydration Transfer.

Amplification-free digital immunoassays (DIAs) typically utilize optical nanoparticles to enhance single immunocomplex molecule detection. The efficiency and uniformity of transferring the nanoparticles from a bulk solution to a solid surface determine the limit of detection (LOD) and the accuracy of DIAs. Previous methods suffer from issues like low efficiency, nonuniform distribution, and particle aggregation. Here, we present a novel technique named synergistic sedimentation of Brownian motion suppression and dehydration transfer (SynSed) for nanoparticles using water-soluble polymers. The efficiency of transferring quantum dots (QDs) was increased from 10.7 to 91.4%, and the variation in QD distribution was restricted to 8.8%. By incorporating SynSed into DIAs, we achieved a remarkable reduction in the LOD (down to 3.9 aM) for carcinoembryonic antigen and expanded the dynamic range to cover 3 orders of magnitude in concentration, ranging from 0.01 to 10 fM. DIAs enhanced with SynSed possess ultrahigh sensitivity, advanced accuracy, and specificity, offering a great premise in early disease diagnostics, risk stratification, and treatment response monitoring.

A novel automated multiplex immunoassay for the ultrasensitive detection of blood‐based biomarkers for neurodegenerative diseases

AbstractBackgroundEfforts to identify accurate blood biomarkers for neurodegenerative disease hallmarks have been hampered by the lack of a proteomic tool that has the required sensitivity to detect very low concentrations of brain‐derived proteins in plasma or serum and the ability to multiplex many analytes in a single assay. Here we evaluated NULISA™, a recently developed novel immunoassay with attomolar level sensitivity and high multiplex capability1, for its ability to detect serum biomarkers associated with Alzheimer’s disease.MethodSerum samples from 31 Alzheimer’s disease (AD) patients and 31 non‐AD controls were analyzed using NULISA with a 200plex inflammation panel targeting a broad spectrum of inflammation‐related cytokines, chemokines and other proteins. Five samples failed quality control and were excluded from further analysis, resulting in 28 AD and 29 control samples in the final dataset. Linear model analysis, including age and sex as covariates, was performed for each target for differential expression between AD patients and controls.ResultTwo significant proteins were identified. The level of glial fibrillary acidic protein (GFAP) was 1.84‐fold higher in AD patients (adjusted p‐value = 0.00014), whereas the level of S100 calcium‐binding protein A12 (S100A12) was 2‐fold higher in non‐AD controls (adjusted p‐value = 0.031). GFAP serum levels correlated strongly with total tau (Spearman rho = 0.69, p = 1.7e‐09), p‐tau181 (rho = 0.69, p = 1.7e‐09) and amyloid beta 42 (rho = ‐0.71, p = 4.7e‐10) levels in cerebrospinal fluid (CSF). S100A12 levels also correlated significantly with total tau (rho = ‐0.39, p = 0.0031), p‐tau181 (rho = ‐0.36, p = 0.0053) and amyloid beta 42 (rho = 0.38, p = 0.0067) CSF levels. Receiver operating characteristic analysis demonstrated that GFAP strongly discriminated AD from controls with an area under the curve (AUC) of 0.93 (95% CI 0.87‐1.0), and S100A12 also exhibited good discrimination with an AUC of 0.72 (95% CI 0.59‐0.86).ConclusionThis exploratory study identified serum GFAP levels as a strong discriminatory biomarker for AD, consistent with previous studies. S100A12 also demonstrated significant associations with AD and CSF biomarkers and thus warrants further study. NULISA holds great promise for the discovery and validation of blood‐based biomarkers for the early detection and monitoring of neurodegenerative diseases.1. Feng, W. et al. bioRxiv 2023.04.09.536130 (2023) https://doi.org/10.1101/2023.04.09.536130.

NULISA: a proteomic liquid biopsy platform with attomolar sensitivity and high multiplexing

The blood proteome holds great promise for precision medicine but poses substantial challenges due to the low abundance of most plasma proteins and the vast dynamic range of the plasma proteome. Here we address these challenges with NUcleic acid Linked Immuno-Sandwich Assay (NULISA™), which improves the sensitivity of traditional proximity ligation assays by ~10,000-fold to attomolar level, by suppressing assay background via a dual capture and release mechanism built into oligonucleotide-conjugated antibodies. Highly multiplexed quantification of both low- and high-abundance proteins spanning a wide dynamic range is achieved by attenuating signals from abundant targets with unconjugated antibodies and next-generation sequencing of barcoded reporter DNA. A 200-plex NULISA containing 124 cytokines and chemokines and other proteins demonstrates superior sensitivity to a proximity extension assay in detecting biologically important low-abundance biomarkers in patients with autoimmune diseases and COVID-19. Fully automated NULISA makes broad and in-depth proteomic analysis easily accessible for research and diagnostic applications.

Attomole Electrochemical Detection of MicroRNAs Based on Surface-Initiated Enzymatic Polymerization Coupled with Copper Enhancement

The sensitive and effective detection of microRNAs (miRNAs) is of great significance since miRNAs have been proven to have undeniable importance in participating in many biological processes. Herein, we present a novel, sensitive, label-free electrochemical miRNA detection method. Three signal amplification techniques are incorporated in this method, including the efficient conjugate of primer-modified polystyrene spheres (PS) with magnetic beads (MBs) triggered by target miRNA, template-free surface-initiated enzymatic polymerization (SIEP) on the primers, and the use of copper ions in square wave voltammetry (SWV) for detecting acidically depurinated primers. Cooperating with the electrochemical approach, this method was able to achieve a detection limit of 120 aM. With an attomole level of sensitivity and easiness of manipulation, this novel method is suitable for miRNA routine detection in both research and clinical aspects.