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A novel immunoassay platform is presented utilizing a cardiac troponin T antibody (Ab-cTnT) labelled with 5-carboxyfluorescein (5-FAM) integrated into a two-dimensional (2D) manganese dioxide nanosheet (MnO 2 NS) matrix. This strategy enables a turn-on response towards cTnT antigen within a mere 10-min incubation period, boasting an impressive lower detection limit of 0.038 ng/mL. Crucially, our probe demonstrates exceptional selectivity amidst the presence of coexisting biomolecules and ions, ensuring precise detection of cTnT. Moreover, the developed platform showcases promising utility in sensing cTnT from spiked human serum samples, yielding satisfactory recovery percentages ranging from 82 to 105%. Additionally, we introduce and easy-to-use and cost-effective test strip for point-of-care detection of cTnT, further enhancing accessibility to critical cardiovascular diagnostics., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

A "turn-on" photon up conversion nano couple based on NaYF 4 : Yb, Tm UCNPs quenched with MnO 2 nanosheet was developed for the rapid and selective detection of cTnT. Herein, MnO 2 nanosheet hold on the surface of Antibody cTnT (Ab-cTnT) conjugated blue emitting up conversion nanoprobe (λ em at 475 nm), which leads to quenching of fluorescence due to energy transfer from photon up conversion nanoparticles to MnO 2 nanosheets. On introducing cTnT antigen to the system, the energy transfer process is hindered due to strong antigen -antibody interface on the surface. This in turn, influences the nano-couples positions and effectively separates up conversion nanoprobe from MnO 2 nanosheets surface resulting in restriction to energy transfer process enabling fluorescence recovery. The developed probe shows a linear response towards cTnT in the range of 0.16-2.77 ng/mL with a Limit of Detection (LoD) of 0.025 ng/mL. The practical feasibility of the nanoprobe is performed with possible coexisting biomolecules. Biological study in human blood serum samples exhibited sufficient recovery percentage in the range of 92-103 % is obtained., Competing Interests: Declaration of competing interest The author declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Cardiovascular disease has remained the world's biggest killer for 30 years. To aid in the diagnosis and prognosis of patients suffering cardiovascular-related disease accurate detection methods are essential. For over 20 years, the cardiac-specific troponins, I (cTnI) and T (cTnT), have acted as sensitive and specific biomarkers to assist in the diagnosis of various types of heart diseases. Various cardiovascular complications were commonly detected in patients with COVID-19, where cTn elevation is detectable, which suggested potential prognostic value of cTn in COVID-19-infected patients. Detection of these biomarkers circulating in the bloodstream is generally facilitated by immunoassays employing cTnI- and/or cTnT-specific antibodies. While several anti-troponin assays are commercially available, there are still obstacles to overcome to achieve optimal troponin detection. Such obstacles include the proteolytic degradation of N and C terminals on cTnI, epitope occlusion of troponin binding-sites by the cTnI/cTnT complex, cross reactivity of antibodies with skeletal troponins or assay interference caused by human anti-species antibodies. Therefore, further research into multi-antibody based platforms, multi-epitope targeting and rigorous validation of immunoassays is required to ensure accurate measurements. Moreover, in combination with various technical advances (e.g. microfluidics), antibody-based troponin detection systems can be more sensitive and rapid for incorporation into portable biosensor systems to be used at point-of care., (Copyright © 2021 Elsevier B.V. All rights reserved.)