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Considering the close association between cardiac troponin I (cTnI) level and various cardiovascular diseases, it becomes essential to explore sensitive and accurate detection methods for monitoring their levels in the early stages of disease. In this work, a magnetic dual-aptamer electrochemical sensor for cTnI detection was constructed in the first utilizing MOF-on-MOF-derived electrocatalyst as a signal amplifier in collaboration with high-efficient separation of magnetic beads (MBs). Employing zeolitic imidazolate framework-67 (ZIF-67) with high surface area as host MOF, MOF-on-MOF heterostructure (ZIF-67@PBA) was facilely prepared by in-situ growth of conductive prussian blue analogue (PBA) as guest MOF onto the surface of ZIF-67 with a simple ion-exchange method. After low-temperature calcination, N doped derived electrocatalyst (N-ZIF-67@PBA) was obtained with intact skeletons and pore structures of MOFs. This not only integrated bimetallic active centers with various valence states and diversiform nanostructures of dual MOF, but endowed N-ZIF-67@PBA 8.3-fold increase of electrocatalytic activity for catalytic amplification. Further using aptamer-modified MBs as capture carriers for recognizing and separating cTnI from complex samples with high specificity, the magnetic dual-aptamer sensor successfully achieved the sensitive detection of cTnI with a low detection limit of 0.31 fg/mL. This work provided a new viewpoint on the use of MOF-on-MOF-derived electrocatalyst for ultrasensitive electrochemical sensing analysis., Competing Interests: Declaration of competing interest The authors 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.)

Programmed cell death protein 1 (PD-1) is one of the coinhibitory checkpoints upon T cell activation, the abnormal expression of which severely threatens host immune modulatation for chronic infection. Thus, fast and sensitive monitoring of PD-1 is of vital importance for early diagnosis and cancer treatment. The current detection methods largely based on enzyme-linked immunosorbent assay (ELISA) require time-consuming incubation and complicated washing steps. Herein, we designed a simple and portable nanofiber paper (NFP)-based fluorescence "off-on" immunosensor for PD-1 rapid determination. Molybdenum disulfide (MoS 2 ) nanosheets modified NFP (MoS 2 -NFP) was employed for adsorbing and immobilizing CdSe/ZnS quantum dots-antibody (QDs-Ab) complex to construct a ready-to-use fluorescent immunosensor. The fluorescent signal of QDs-Ab was initially quenched by MoS 2 under the Förster resonance energy transfer (FRET) effect. When the PD-1 target was specifically captured onto NFP by immunization, the QDs-Ab-PD-1 complex was promptly desorbed from the MoS 2 -NFP surface, resulting in FRET impediment and fluorescence recovery. As an alternative quenching agent, graphene oxide (GO) served as a contrast to investigate NFP-based sensing performance. Owing to superior quenching and desorption efficiency, the MoS 2 -NFP-based fluorescence immunosensor exhibited nearly 2-fold lower detection limit (85.5 pg/mL) than GO-NFP-based sensor (151 pg/mL) for PD-1 monitoring. Excellent selectivity and satisfactory recovery in PD-1 mouse cell culture supernatant samples were confirmed as well. In addition, the comparable detectability of the MoS 2 -NFP-based immunosensor was accurately evaluated by a standard PD-1 mouse ELISA kit. This study displayed a simple, rapid, low-cost, and portable point-of-care PD-1 assay, indicating its broad application prospect toward clinical diagnoses.