Ultra-sensitive facile CdS nanocrystals-based electrochemical biosensor to detect myocardial infarction marker troponin

•A new, simple, cost-effective, and rapid way was introduced for the synthesis monodispersed CdS QDs.•A novel immunosandwich biosensor was engineered to serve as a promissing tool for the detection of cardiac troponin marker.•The biosensor revealed a LOD of 2 ng L−1 and a LDR of 5–1000 ng L−1 compare to existing cut-off (13–20 ng L−1).