A dual-mode colorimetric–photothermal LFIA platform was successfully constructed for the detection of thrombosis-related biomarkers, including thrombomodulin and α2-plasmin inhibitor–plasmin complex, in clinical serum samples, enhancing analytical sensitivity and reliability.
Abstract
Lateral flow immunoassay (LFIA) using gold nanoparticles (AuNPs) as signal labels is widely utilized for point-of-care diagnostics. However, it is typically limited by a single colorimetric readout and insufficient sensitivity. To address these limitations, polydopamine nanoparticles (PDANs) were introduced as alternative signal labels to enhance LFIA sensitivity. Owing to their high molar extinction coefficient and broadband absorption spanning the ultraviolet to near-infrared region, PDANs provide strong visual contrast and efficient photothermal conversion capability. Based on these advantages, a dual-mode colorimetric–photothermal LFIA platform was successfully constructed for the detection of thrombosis-related biomarkers, including thrombomodulin (TM) and α2-plasmin inhibitor–plasmin complex (PIC), in clinical serum samples. Under optimized conditions, the visual limits of detection (vLOD) for TM and PIC were 5 ng mL−1 and 50 ng mL−1, respectively. Subsequently, a convenient photothermal readout was introduced, and photothermal signal amplification further improved the sensitivity by approximately 10-fold for TM and 2.5-fold for PIC, achieving dual-mode detection. Clinical validation using 48 serum samples demonstrated good agreement with the clinical method. Overall, this PDANs-based LFIA platform enhances analytical sensitivity and reliability, providing a feasible strategy for the advancement of LFIAs.
Lateral flow immunoassay (LFIA) has been widely used for rapid on-site analysis because of its simplicity, portability, and low cost. However, its performance in competitive assays, particularly for small molecule toxins, remains limited, as the properties of antibodies and the reliance on single-mode signal often lead to insufficient sensitivity and reliability. To address this challenge, we developed an enhanced colorimetric-photothermal LFIA by integrating linker-optimized bivalent nanobodies (BvNbs) and gold-liposome nanocomposites (Au-LNCs). Using tetrodotoxin (TTX) as a representative analyte, a series of BvNbs with different linker lengths were constructed. Molecular docking and molecular dynamics simulations further demonstrated that linker length modulates BvNbs detection performance by regulating conformational stability, local flexibility, and persistent interactions with free target molecules. In parallel, photothermal Au-LNCs were prepared, which exhibited broadband near-infrared absorption and a photothermal conversion efficiency as high as 78.06%. The resulting LFIA achieved a photothermal LOD of 1.89 ng/mL, corresponding to an approximately 10.7-fold improvement in sensitivity compared with conventional colloidal gold-based LFIA, while maintaining good reliability in real samples. Overall, this study provides mechanistic insight into the rational design of BvNbs and a promising strategy for improving LFIA performance.
Jinzhi Han, Hongzhi Liang, Lin Luo et al.· Biosensors & bioelectronics· 0 citations
A dual-aptamer-based, dual-mode FRET lateral flow strip is developed for the rapid and sensitive detection of thrombin in serum samples, achieving a fluorescence-based detection limit of 0.135 nM-twice as sensitive as the colorimetric method.
A preliminary evaluation using serum samples from five breast cancer patients and five healthy individuals showed clearly distinguishable colorimetric and fluorescent responses between the two groups, supporting the effectiveness of the proposed probe for miRNA-21 detection in real serum samples and indicating the potential of the dual-signal LFA platform for further clinical application.
Ruien Shi, Qian Xiang, Yajuan Chang et al.· Talanta: The International J...· 0 citations
BACKGROUND
Foodborne pathogens remain a major threat to public health and food safety, among which Salmonella typhimurium is a leading cause of bacterial foodborne illness. Conventional culture-, immunoassay-, and nucleic-acid-based methods are reliable but often require laboratory facilities, trained personnel, and relatively long processing times, limiting their use for rapid on-site screening. Lateral flow immunoassays are attractive for field detection but commonly suffer from limited sensitivity and subjective visual interpretation. This study addresses the need for a rapid, specific, and more sensitive on-site assay for S. typhimurium.
RESULTS
We developed a phage-assisted colorimetric-photothermal dual-readout lateral flow immunoassay using zeolitic imidazolate framework-67-aggregated gold nanoparticles (ZIF-67@AuNPs) as signal probes. The ZIF-67 scaffold promoted dense AuNP assembly and aggregation-induced localized surface plasmon resonance coupling, resulting in broadened visible absorption around 650 nm and enhanced photothermal conversion. ZIF-67@AuNPs achieved a photothermal conversion efficiency of 45.7%, markedly higher than that of AuNPs alone (22.7%). Phage-based capture and antibody-functionalized ZIF-67@AuNPs enabled selective recognition of S. typhimurium on the test strip. In the colorimetric mode, the assay showed a linear range of 3 × 104-1 × 107 CFU/mL with a visual limit of detection (LOD) of 3.0 × 104 CFU/mL. In the photothermal mode, the linear range was 103-106 CFU/mL and the LOD improved to 0.997 × 103 CFU/mL, giving approximately 30-fold higher sensitivity.
SIGNIFICANCE AND NOVELTY
This work introduces a MOF-assisted LFIA that integrates phage-based biorecognition with colorimetric screening and photothermal quantification in a single test strip. The strategy reduces reliance on subjective visual judgment while retaining operational simplicity. The platform provides a practical approach for rapid on-site detection of S. typhimurium and can be extended to other foodborne pathogens by changing the recognition elements.
Lun Luo, Renjie Zhou, Wenhai Wang et al.· Analytica Chimica Acta· 0 citations
A substrate-free dual-mode lateral flow immunoassay using intrinsically colored Prussian Blue nanoparticles (PB NPs) as multifunctional signal reporters is developed, providing a simple, rapid, and reliable approach for S. aureus detection with strong potential for point-of-care testing.
Wenchao Min, Zhengyi Cai, Jinrui Lu et al.· Spectrochimica Acta Part A -...· 0 citations
A compartmentalization-free electrochemiluminescence (ECL) digital immunoassay based on silica-coated gold nanorod (AuNR@SiO2) for detecting tumor necrosis factor-α secreted by activated T cells and demonstrates promising potential for clinical translation.
Yajuan Yan, Jialian Ding, Tengyu Li et al.· Analytical Chemistry· 1 citation