Starch-based labelling for electrochemical lateral flow immunoassays.

A bio-conjugated 2D photonic crystal hydrogel-based immunoassay for glycocholic acid.

Hepatocellular carcinoma (HCC) remains a leading cause of cancer-related mortality worldwide, underscoring an urgent need for reliable point-of-care testing (POCT) tools. Glycocholic acid (GCA), owing to its high specificity and sensitivity, has been recognised as a promising biomarker for HCC. Nevertheless, current GCA detection methodologies still suffer from drawbacks, including high cost, cumbersome procedures, prolonged assay times, and single-use formats. In this study, a novel label-free immunoassay based on a two-dimensional photonic crystal hydrogel (2D-PCH) has been reported, which enabled visual, quantitative, and reusable detection of GCA. Unlike conventional direct-detection strategies, the developed 2D-PCH employed antigen-antibody complexes as reversible non-covalent crosslinkers within the hydrogel network. Competitive binding between free GCA and the grafted antigen for the limited antibody sites disrupted these crosslinks, reducing the crosslinking density and triggering hydrogel swelling. This volumetric expansion increased the particle spacing of the embedded photonic crystal array, which was quantitatively reflected by an increase in the Debye diffraction ring diameter, accompanied by a visible structural colour shift. The 2D-PCH sensor achieved a limit of detection (LoD) of 3.66 µg mL-1 and a linear detection range spanning from 10 to 50 µg mL-1. Moreover, the developed 2D-PCH displayed excellent specificity, good reversibility and satisfactory recovery ranging from 93.02% to 106.07% towards spiked samples. Therefore, the developed 2D-PCH-based immunoassay provided a visual, label-free, convenient, quantitative and reusable POCT method for the biomarker GCA, with great potential for future HCC clinical screening applications.

A Magnetic Molecularly Imprinted Electrochemical Sensor for Glycoprotein Detection via the Glutaraldehyde Cross-Linking Strategy

Magnetic electrochemical sensors (MECs) are robust bioanalytical devices because of their high selectivity, strong antifouling ability, low cost, and simple operation properties. However, since many biomolecules are nonelectroactive, achieving their electrochemical determination is still a huge challenge. In this report, a sensitive electrochemical sensor was developed by glutaraldehyde cross-linking of electroactive tyrosine (Tyr) on the glycoprotein chains at the magnetic molecularly imprinted nanoparticle surface. Thus, the electrochemical detection of glycoproteins can be indirectly achieved by the determination of Tyr. The usefulness of the method was evaluated using the carcinoembryonic antigen (CEA) and ovalbumin (OVA) as model glycoproteins. The proposed method exhibited linear responses for OVA and CEA over concentration ranges of 10 ng mL–1 to 10 μg mL–1 and 10 ng mL–1 to 1 μg mL–1, with LODs (3σ) of 2.03 ng mL–1 and 1.56 ng mL–1, respectively. Consequently, the proposed signal conversion strategy provides new ideas for designing and preparing a novel magnetic electrochemical sensor.

Polydopamine nanoparticle-based colorimetric–photothermal dual-mode lateral flow immunoassay for thromboembolism diagnosis

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.

Graphdiyne oxide as a high-capacity biointerface for multiplexed electrochemical immunosensing of neutrophil biomarkers.

Electrochemical aptasensor based on DNA nanoflowers for the sensitive detection of acrylamide.

As a prevalent heat-induced byproduct, acrylamide (AA) is frequently generated during thermal food processing, particularly in baked and fried goods. It is a Group 2A carcinogen produced via the Maillard reaction and exhibits neurotoxicity as well as reproductive and developmental toxicity. In this work, DNA nanoflowers (DNF) with remarkable signal amplification were integrated with methylene blue (MB) to fabricate a novel, high-performance electrochemical signal probe. The high affinity and selective recognition of the aptamer toward AA effectively prevents the signal probe from attaching to the electrode surface, enabling ultrasensitive, quantitative electrochemical detection of AA. Under optimal conditions, the proposed sensor achieved an ultra-low limit of detection of 0.948 pM, with a linear response spanning from 0.005 to 500 nM. Moreover, the sensor exhibited exceptional anti-interference capacity, satisfactory reproducibility, favourable repeatability, and long-term operational stability. Detection of actual samples and quality-control samples confirms the reliability of the sensor, indicating promising applications for AA detection and providing a new approach in this field.

Fluorescent nanozyme-based biosensors: Classification, catalytic mechanisms, and emerging applications