Colorimetric Detection of HER2‐Overexpressing‐Cancer‐Derived Exosomes in Mouse Urine Using Magnetic‐Polydiacetylene Nanoparticles

Abstract

AbstractBreast cancer (BC) is a major global health problem, with ≈20–25% of patients overexpressing human epidermal growth factor receptor 2 (HER2), an aggressive marker, yet access to early detection and treatment varies across countries. A low‐cost, equipment‐free, and easy‐to‐use polydiacetylene (PDA)‐based colorimetric sensor is developed for HER2‐overexpressing cancer detection, designed for use in low‐ and middle‐income countries (LMICs). PDA nanoparticles are first prepared through thin‐film hydration. Subsequently, hydrophilic magnetic nanoparticles and HER2 antibodies are sequentially conjugated to them. The synthesized HER2‐MPDA can be concentrated and separated by a magnetic field while inheriting the optical characteristics of PDA. The specific binding of HER2 antibody in HER2‐MPDA to HER2 receptor in HER2‐overexpressing exosomes causes a blue‐to‐red color change by altering the molecular structure of the PDA backbone. This colorimetric sensor can simultaneously separate and detect HER2‐overexpressing exosomes. HER2‐MPDA can detect HER2‐overexpressing exosomes in the culture medium of HER2‐overexpressing BC cells and in mouse urine samples from a HER2‐overexpressing BC mouse model. It can selectively isolate and detect only HER2‐overexpressing exosomes through magnetic separation, and its detection limit is found to be 8.5 × 108 particles mL−1. This colorimetric sensor can be used for point‐of‐care diagnosis of HER2‐overexpressing BC in LMICs.