Multilayered Mesoporous Composite Nanostructures for Highly Sensitive Label-Free Quantification of Cardiac Troponin-I

Abstract

Cardiac troponin-I (cTnI) is a well-known biomarker for the diagnosis and control of acute myocardial infarction in clinical practice. To improve the accuracy and reliability of cTnI electrochemical immunosensors, we propose a multilayer nanostructure consisting of Fe3O4-COOH labeled anti-cTnI monoclonal antibody (Fe3O4-COOH-Ab1) and anti-cTnI polyclonal antibody (Ab2) conjugated on Au-Ag nanoparticles (NPs) decorated on a metal–organic framework (Au-Ag@ZIF-67-Ab2). In this design, Fe3O4-COOH was used for separation of cTnI in specimens and signal amplification, hierarchical porous ZIF-67 extremely enhanced the specific surface area, and Au-Ag NPs synergically promoted the conductivity and sensitivity. They were additionally employed as an immobilization platform to enhance antibody loading. Electron microscopy images indicated that Ag-Au NPs with an average diameter of 1.9 ± 0.5 nm were uniformly decorated on plate-like ZIF-67 particles (with average size of 690 nm) without any agglomeration. Several electrochemical assays were implemented to precisely evaluate the immunosensor performance. The square wave voltammetry technique exhibited the best performance with a sensitivity of 0.98 mA mL cm−2 ng−1 and a detection limit of 0.047 pg mL−1 in the linear range of 0.04 to 8 ng mL−1.

Efficient electrochemical CO2 conversion by cobalt-based metal organic frameworks modified by bimetallic gold–silver nanostructures

“…This finding confirms more favorable conditions for Au electrodeposition, in agreement with previous reports. 6 In contrast to Ag@ZIF-67 and Au@ZIF-67, the concurrent electrodeposition of Au–Ag NPs on the MOF/GC electrode resulted in the homogeneous formation of Au–Ag alloys (23 ± 4 nm) on the surface of the ZIF-67 particles (Fig. 1d and S2c†).…”

“…The polyhedral shape of the MOF was retained during electrodeposition, which effectively prevented agglomeration of the Au–Ag alloy. 6…”

“…ZIF-67 was synthesized according to the literature. 6 Briefly, 520 mg CoCl 2 was dissolved in 40 mL methanol. A solution of 600 mg PVP and 2.63 g 2-methylimidazole in 40 mL methanol was prepared.…”

“…The organic linkers connecting metallic cores in MOFs play a crucial role in species adsorption. 5 ZIF-67 is a cobalt-based MOF with a significant SSA (around 1700 cm 2 g −1 ) 6 and an acceptable electroactivity. 7 Co ions provide ideal catalytic sites due to their various valence states and partially occupied 3d orbitals.…”

Toward waterborne protozoa detection using sensing technologies

“…The importance of food and water safety in various industries has led to the mining and improvement of nanoscale analytical devices known as nanobiosensors. Due to the numerous advantages of these devices such as portability, low cost, rapid assay time, ease of use, and high selectivity and sensitivity (Terry et al, 2005;Ahmadi et al, 2022;Khoshfetrat et al, 2022;Saeidi et al, 2022), particularly for the detection of infectious agents and pollutants in the environment (Pejcic et al, 2006;Sin et al, 2014;Ahmadi et al, 2021c), focus on the fabrication of biosensors as a diagnostic technology for the detection of different analytes in food, water, and environmental samples has intensely increased (Terry et al, 2005;Pejcic et al, 2006;Metkar and Girigoswami, 2018;Salouti and Khadivi derakhshan, 2020) (Figure 1).…”