Novel manufacturing systems for cancer diagnosis using ultra-sensitive photonic crystal fiber biosensor with dual-functionalized aptamer-nanocavity

Early detection of cancer significantly improves treatment outcomes and survival rates. Conventional diagnostic methods often lack the sensitivity and specificity required for early-stage detection. To address this, proposed work developed an enhanced sensitivity photonic crystal fiber (PCF) biosensor incorporating a novel dual-functionalized aptamer-nanocavity technique based on surface plasmon resonance (SPR). The sensor design integrates advanced PCF structures with a plasmonic layer of gold nanoparticles (AuNPs) and nanocavities functionalized with specific aptamers to selectively capture cancer biomarkers.Methodologically, the PCF was fabricated using the stack-and-draw technique, with precise control over the air hole diameter (2 μm), pitch (5 μm), and core diameter (10 μm). A plasmonic layer of AuNPs was deposited on the inner walls of the air holes, and nanocavities were etched into the PCF structure. These nanocavities awere coated with a secondary layer of aptamers, creating dual-binding sites to enhance biomarker capture. Simulations using the Finite Element Method (FEM) and Finite-Difference Time-Domain (FDTD) techniques optimized the design. Experimental results demonstrated a detection limit of 10 femtomolar (fm) for cancer biomarkers, significantly surpassing traditional SPR-based sensors with detection limits in the nanomolar range. Specificity tests with non-target molecules showed minimal cross-reactivity, confirming the high selectivity of the sensor. In tests with clinical samples, the biosensor reliably detected biomarkers, indicating its potential for practical application in early cancer diagnostics.