Functionalizing of magnetic nanoparticles as nano-architecture towards bioimaging and colorimetric recognition of MCF-7 cells: dual opto-sensing and fluorescence monitoring for early-stage diagnosis of breast cancer

Considering the high incidence of breast cancer, a sensitive and specific approach is crucial for its early diagnosis and follow-up treatment. Folate receptors (FR), which are highly expressed on the epithelial tissue such as breast cancer cells (e.g., MCF-7), have been used in cancer diagnosis and bioimaging. This study presents an innovative colorimetric and fluorescence bioimaging platform towards MCF-7 using folic acid (FA)-conjugated iron-oxide magnetite silica-based nanocomposite (Fe₃O₄@SiO₂-3-aminopropyl)triethoxysilane (APTES-NH₂)@cysteine (Cyt)-Cyt@FA). For identification of MCF-7, the polyvinylpyrrolidone (PVP)-capped-platinum (Pt) nanoparticle was utilized as a nanozyme to catalyze the reaction between 3,3′,5,5′-tetramethylbenzidine (TMB) and H₂O₂ for visual detection of MCF-7 cells. Colorimetric changes are detectable by the naked eye and spectrophotometry at the wavelength of 450 nm, with a linear range of 50–5000 cells/mL and a detection limit of 30 cells/mL. The Fe₃O₄@SiO₂-APTES-NH₂@Cyt-Cyt@FA complex was modified with rhodamine B as a fluorescence bioimaging probe to monitor FR-overexpressed MCF-7 cells. The nanocomposite is biocompatible with a toxicity threshold of about 800 µg/mL. These methodologies facilitate bioimaging and colorimetric assays without sophisticated instrumentation, offering high specificity, sensitivity, repeatability, and stability, making them suitable as versatile methods for detecting and bioimaging cancer cells.

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