Fluorescence-Enhanced Inverse Opal Photonic Crystal Hydrogels Suspension Array Integrated with Aptamer-Antibody Dual-Recognition Sandwich Assay for Breast Cancer Subtypes Discrimination

Breast cancer remains one of the leading causes of cancer-related mortality among women worldwide, while accurate diagnosis and molecular subtype classification are crucial for effective treatment and prognosis. Herein, a fluorescence-enhanced biosensor integrating inverse opal photonic crystal hydrogels (IOPCHs) with an aptamer-antibody sandwich assay is presented for simultaneous detection of multiple breast cancer protein biomarkers. Silica nanoparticles (SiO₂) with controlled diameters are used to fabricate IOPCHs exhibiting distinct photonic band gaps (PBGs). By exploiting the strong spectral overlap between PBGs and fluorophore emission peaks, IOPCHs display remarkable fluorescence enhancement effects, which have been systematically demonstrated for the first time. The sensor effectively detects carcinoembryonic antigen (CEA), cancer antigen 15-3 (CA15-3), and human epidermal growth factor receptor 2 (HER2) in clinical serum samples, enabling precise discrimination of Luminal A, Luminal B, HER2-positive (HER2+), and triple negative breast cancer (TNBC) subtypes. Principal component analysis (PCA) further confirms the diagnostic potential. With high sensitivity and specificity, this biosensor offers a robust and versatile platform for early, rapid, and precise breast cancer diagnosis, as well as for delineating characteristic protein profiles in high-risk populations to inform individualized prevention and treatment strategies, warranting further validation in large-scale clinical investigation.