# Highly Sensitive Biosensor for the Detection of Cardiac Troponin I in Serum via Surface Plasmon Resonance on Polymeric Optical Fiber Functionalized with Castor Oil-Derived Molecularly Imprinted Nanoparticles

## TL;DR

A new biosensor using castor oil-based nanoparticles and fiber optics detects heart attack biomarkers in blood with high sensitivity.

## Contribution

A novel biosensor using castor oil-derived molecularly imprinted nanoparticles and POF-SPR for rapid and sensitive cTnI detection.

## Key findings

- The sensor detects cardiac troponin I with a limit of detection of 3.53 × 10−15 M.
- The sensor works effectively in both buffer and serum matrices within 10 minutes.
- The cTnI_nanoMIP-SPR outperforms existing sensor platforms in sensitivity and selectivity.

## Abstract

In this work, we report the development of a highly sensitive optical sensor for the detection of cardiac troponin I (cTnI), a key biomarker for early-stage myocardial infarction diagnosis. The sensor combines castor oil-derived biomimetic receptors, called GreenNanoMIPs and prepared via the molecular imprinting technology using as a template an epitope of cTnI (i.e., the NR10 peptide), with a portable multimode plastic optical fiber surface plasmon resonance (POF-SPR) transducer. For sensing, gold SPR chips were functionalized with GreenNanoMIPs as proven by refractive index changes and confirmed by means of XPS. Binding experiments demonstrated the cTnI_nanoMIP-SPR sensor’s ability to detect both the NR10 peptide epitope and the full-length cTnI protein within minutes (t = 10 min), with high sensitivity and selectivity in buffer and serum matrices. The cTnI_nanoMIP-SPR showed an LOD of 3.53 × 10−15 M, with a linearity range of 1 pM–100 pM, outperforming previously reported sensor platforms and making it a promising tool for early-stage myocardial infarction detection.