Flexible gold nanoparticle SERS tape for rapid, label-free and ultrasensitive detection and differentiation of Shiga toxin variants

Corrigendum to “Flexible gold nanoparticle SERS tape for rapid, label-free and ultrasensitive detection and differentiation of Shiga toxin variants” [Biosens. Bioelectron. X 27 (2025) 100696

Electrochemical biosensors utilizing hybridization chain reaction (E-HCR) have witnessed substantial advancement over the past two decades, yet achieving simultaneous rapid and ultrasensitive detection remains a challenge with current strategies. Herein, we report a portable, wireless E-HCR biosensor that leverages S9.6 antibody-mediated bivalent capture for ultrasensitive nucleic acid detection, achieving a record-fast assay completion time. The detection mechanism involves target nucleic acid-triggered opening of a hairpin probe, followed by hybridization with a preassembled HCR/HRP amplifier. The resulting target/hairpin/HCR/HRP complex contains two segments of DNA/RNA heteroduplex, enabling efficient capture by an S9.6 antibody-modified screen-printed carbon electrode (SPCE) through bivalent S9.6 antibody-heteroduplex interactions. The bivalent capture strategy demonstrates a 1.6-fold enhancement over single-site S9.6 antibody-heteroduplex binding and a 3.1-fold improvement in capture efficiency compared to monovalent hybridization. This one-pot strategy offers three unique advantages. First, the integration of bivalent capture, homogeneous hybridization, and preformed HCR/HRP amplifiers enables the heterogeneous E-HCR assay to be completed within 34 min, significantly faster than conventional methods. Second, optimization of HCR amplifier and background signal suppression achieves a high signal-to-noise ratio, facilitating ultrasensitive nucleic acid detection. Third, the biosensor features wireless signal output and utilizes low-cost SPCE, making it suitable for point-of-care applications. Collectively, these unique merits enable the bivalent capture biosensor to achieve portable, one-pot, rapid, and ultrasensitive nucleic acid detection, addressing limitations in current E-HCR biosensing platforms.

Surface-enhanced Raman spectroscopy (SERS) microfluidic chips for label-free and ultrasensitive detection are fabricated by integrating a plasmonic supercrystal within microfluidic channels. This plasmonic platform allows the uniform infiltration of the analytes within the supercrystal, reaching the so-called hot spots. Moreover, state-of-the-art simulations performed using large-scale supercrystal models demonstrate that the excellent SERS response is due to the hierarchical nanoparticle organization, the interparticle separation (IPS), and the presence of supercrystal defects. Proof-of-concept experiments confirm the outstanding performance of the microfluidic chips for the ultradetection of (bio)molecules with no metal affinity. In fact, a limit of detection (LOD) as low as 10-19 M was reached for crystal violet. The SERS microfluidic chips show excellent sensitivity in the direct analysis of pyocyanin secreted by Pseudomonas aeruginosa grown in a liquid culture medium. Finally, the further integration of a silica-based column in the plasmonic microchip provides charge-selective SERS capabilities as demonstrated for a mixture of positively and negatively charged molecules.

Metal-organic frameworks (MOFs) have attracted widespread interest due to their unique and unprecedented advantages in microstructures and properties. Besides, surface-enhanced Raman scattering (SERS) technology has also rapidly developed into a powerful fingerprint spectroscopic technique that can provide rapid, non-invasive, non-destructive, and ultra-sensitive detection, even down to single molecular level. Consequently, a considerable amount of researchers combined MOFs with the SERS technique to further improve the sensing performance and broaden the applications of SERS substrates. Herein, representative synthesis strategies of MOFs to fabricate SERS-active substrates are summarized and their applications in ultra-sensitive biomedical trace detection are also reviewed. Besides, relative barriers, advantages, disadvantages, future trends, and prospects are particularly discussed to give guidance to relevant researchers.

An ultrasensitive dual-mode stagey for 17β-estradiol assay: Photoelectrochemical and colorimetric biosensor based on a WSe2/TiO2-modified electrode coupled with nucleic acid amplification

Rapid and ultra-sensitive trace metals detection of water by partial Leidenfrost superhydrophobic array surface enhanced laser-induced breakdown spectroscopy

Label-free detection technologies, such as surface plasmon resonance (SPR), have emerged as powerful tools for biomarker detection due to their unique capabilities. However, their widespread adoption has been hindered by challenges such as complex biochip fabrication, cumbersome optical systems, and limited sensitivity. To address these limitations, we present a novel large-core biconical-fiber embedded optofluidic biochip (LBOB) that innovatively integrates multimode interference (MMI), Fresnel reflection, and a large-core biconical fiber biosensor. The LBOB eliminates complex noble-metal coatings and precise optical alignment in traditional label-free biosensors through employing a large-core biconical fiber sensor and all-fiber optical architecture. These advancements confer exceptional sensitivity, superior biocompatibility, facile functionalization, cost-effectiveness (<$0.25 per sample), and portability. Leveraging multimodal signal enhancement mechanisms, the LBOB achieves an outstanding sensitivity of 1.8 × 10-6 RIU. The use of the large-core biconical fiber biosensor significantly increases the number of biomolecules immobilized on the biosensing surface and enhances light-matter interactions, further boosting sensitivity. Beyond biomolecular interaction analysis, the LBOB demonstrates remarkable utility in the rapid (<10 min) and ultrasensitive detection of hepatitis biomarkers, achieving detection limits of 0.0008 IU/mL for HBsAg and 0.12 ng/mL for cholyglycine in serum. The LBOB represents a transformative tool for biomarker detection, establishing a novel paradigm for label-free biomolecular detection and interaction analysis.

Dual-catalytic hairpin amplification strategy as a highly efficient signal amplifier cooperative with COF@Au for ultrasensitive SERS detection of miRNA-21.

Label free, electrochemical detection of atrazine using electrospun Mn2O3 nanofibers: Towards ultrasensitive small molecule detection

Ultra-sensitive and selective label free electrochemical DNA detection at layer-by-layer self-assembled graphene oxide and vesicle liposome nano-architecture

Ultra-sensitive and rapid detection of Salmonella enterica and Staphylococcus aureus to single-cell level by aptamer-functionalized carbon nanotube field-effect transistor biosensors

Label-free, ultrasensitive and rapid detection of FDA-approved TBI specific UCHL1 biomarker in plasma using MWCNT-PPY nanocomposite as bio-electrical transducer: A step closer to point-of-care diagnosis of TBI

Asymmetric polymerase chain reaction and loop-mediated isothermal amplification (AP-LAMP) for ultrasensitive detection of microRNAs

The detection of monoamine neurotransmitters has become a vital research subject due to their high correlations with nervous system diseases, but insufficient detection precisions have obstructed diagnosis of some related diseases. Here, we focus on four monoamine neurotransmitters, dopamine, norepinephrine, epinephrine, and serotonin, to conduct their rapid and ultrasensitive detection. We find that the low-frequency (<200 cm-1) Raman vibrations of these molecules show some sharp peaks, and their intensities are significantly stronger than those of the high-frequency side. Theoretical calculations identify these peaks to be from strong out-of-plane vibrations of the C-C single bonds at the joint point of the ring-like molecule and its side chain. Using our surface enhanced low-frequency Raman scattering substrates, we show that the detection limit of dopamine as an example can reach 10 nM in artificial cerebrospinal fluid. This work provides a useful way for ultrasensitive and rapid detection of some neurotransmitters.

Background: The detection and quantification of low frequency circulating tumor DNA (ctDNA) variants in plasma are essential for early cancer diagnosis and monitoring but remain challenging at variant allele frequencies (VAFs) below 1%. This study combines the clinically relevant reference standards to simulate low frequency ctDNA variants with the high sensitivity of the PacBio Onso sequencing system, which utilizes highly accurate sequencing by binding (SBB) chemistry, and nRichDX’s large-volume extraction capabilities. Together, these advancements aim to improve detection accuracy, enhance diagnostic reliability, and facilitate earlier intervention in oncology by overcoming the limitations of low plasma volumes. Methods: Spike in experiments were conducted using SeraCare ctDNA reference v4 material in plasma from healthy patients, with VAFs of 0.1% and 0.01%selected to represent challenging low-frequency levels common in clinical ctDNA detection as well as 0% (wild type control). Experiments were performed with 5 mL and 20 mL plasma volumes, with three replicates per condition. cfDNA was extracted using both nRichDX and Qiagen kits for comparison. Extracted cfDNA underwent library preparation, hybridization capture, library conversion, quality control, equimolar pooling, and sequencing on the Onso platform. Variant calling and data analysis were conducted to assess extraction sensitivity and detection performance at these low VAF levels. Results: The study demonstrated that detecting low frequency variants at 0.1% and 0.01% VAF was challenging in 5 mL plasma samples, regardless of the extraction method, due to the inherent difficulty of capturing such low variant frequencies in smaller volumes. In contrast, the nRichDX system successfully detected these low frequency variants in 20 mL plasma samples, whereas the Qiagen kit showed limited recovery at these levels. Additionally, the nRichDX workflow was more streamlined and efficient compared to Qiagen, further emphasizing the advantages of nRichDX for larger sample volumes and low frequency variant detection. Conclusions: These findings emphasize the critical importance of using larger plasma volumes to detect lower VAFs effectively and increase overall sensitivity in liquid biopsy applications. The nRichDX system’s strong performance with 20 mL samples, combined with its no-transfer process that leaves no targets behind, suggests its potential for improved sensitivity in early cancer detection. Combining the nRichDX system with the increased sequencing accuracy of SBB on the PacBio Onso resulted in maximum recovery for low-frequency variants. This can inform clinical practices to optimize sample volume and extraction methods as well as sequencing performance for accurate identification of low-frequency ctDNA variants. Citation Format: Mayer Saidian, Alex Sockell, Dan Nasko, Ian McLauglin, Jason Saenz, Carlos Hernandez, Andrew Dunnigan, Leila Aghili, Nafiseh Jafari. Ultra sensitive detection and quantification of low frequency variants in plasma using nRichDX extraction and PacBio SBB sequencing [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 4571.