Acute myocardial infarction (AMI) is a serious health problem that must be identified in its early stages. Considerable progress has been made in understanding the condition of AMI through ascertaining the role of biomarkers, such as myoglobin, cardiac troponin proteins (T and I), creatine kinase-MB, and fatty acid-binding protein (FABP). A field-effect transistor (FET) is an effective platform; however, innovations are required in all layers of the FET for it to become robust and highly sensitive. For the first time, we made use of the synergistic combination of noble metal nanoparticles (AuNPs) with Co₃O₄ for the detection of cardiac troponin T (cTnT) in a FET platform. We determined the morphology of Au-decorated Co₃O₄ NRs and their electronic properties by characterizing the channel layer using electron microscopies and transient measurements. Subsequently, we performed the detection of cardiac troponin T by immobilizing its complementary biotinylated DNA aptamer on the channel surface using a drop-casting method. To understand the changes in drain current caused by this interaction, we probed our SWCNT–Co₃O₄ NR transistor with limited gate and drain bias (≤1 V), achieving a sensitivity of 0.5 μA μg⁻¹ mL⁻¹ for the Au-decorated NRs. A 250% increase in the sensitivity and a limit of detection (LOD) of 0.1 μg mL⁻¹ were achieved by using this device. Finally, selectivity studies proved that this synergistic combination works well in the FET configuration for the successful detection of cTnT.

Microcantilever-based sensor platform has attracted a lot of attention over the time in detection of a variety of molecules due to their miniaturized dimensions. Sensitivity enhancement is an important aspect of such sensors, especially when used for point-of-care diagnostic purpose. However, the major concern while operating these sensors in deflection mode is their sensitivity which mainly relies on selective chemical modification protocols employed on these sensor surfaces. One of the ways of getting better sensitivity is through asymmetric (one side) biofunctionalization of the sensor surface. In the presented work here, we have demonstrated a novel approach of asymmetric biofunctionalization of proteins in overall sensitivity enhancement of piezoresistive silicon nitride-oxide microcantilever sensor platform inside a flow chamber. Herein, using our developed surface chemistry, asymmetrically biofunctionalized microcantilevers first exhibited a greater electrical response in terms of piezoresistance change than their symmetric counterpart in the detection of human immunoglobulins (HIgGs) protein. Finally, these microcantilevers were employed to exhibit the enhanced sensitivity towards the detection of a crucial cardiac marker protein, i.e. Troponin-I (cTnI) down to 250 ng ml ⁻¹ using asymmetric biofunctionalization process. This study shows that the developed asymmetric biofunctionalization methodology may be used as a general protocol to detect other important biomarkers of clinical applications with improved sensitivity.

Binding configuration of ade novostapled peptide on SARS-CoV-2 spike protein, as predicted by molecular simulation. Stapled residues enhance peptide stability while interacting residues engage key amino acids on the protein receptor-binding domain.