# Ultrasensitive Microfiber Biosensor with Synergistic Sensitization of Gold Nanoparticles and Two-Dimensional Material Black Phosphorus for Detection of BRCA1 Gene Synthetic Sequence

## TL;DR

A new ultra-sensitive biosensor was developed using gold nanoparticles and black phosphorus to detect a breast cancer-related gene sequence at very low concentrations.

## Contribution

The synergistic combination of black phosphorus and gold nanoparticles for enhanced biosensing of BRCA1 gene sequences is novel.

## Key findings

- The sensor achieved a sensitivity of 0.793 nm/lgM and a detection limit of 20.27 fM.
- BP-functionalized sensors showed superior dynamic range and lower detection limits compared to traditional methods.
- The AuNPs amplified the signal, while BP enhanced the interfacial sensitization for improved performance.

## Abstract

Sensitive quantitative detection of breast cancer gene synthetic sequences is crucial for related biosensing research. To address the limitations of traditional sensors for detecting ultra-low concentrations, this study developed a novel fiber-optic biosensor by combining nanomaterial sensitization with nanoparticle signal amplification strategies. A fiber optic sensor based on single-mode fiber-thin-core fiber-multimode fiber-single-mode fiber structure was fabricated and functionalized with black phosphorus (BP) nano-interface. The Au@cDNA complex was prepared by covalently immobilizing sulfhydryl-modified complementary DNA (cDNA) on the surface of gold nanoparticles (AuNPs). The complex specifically hybridized with the probe DNA (pDNA) immobilized on the surface of the sensor. The experimental results show that this sensor has a sensitivity of 0.793 nm/lgM and a detection limit of 20.27 fM in the concentration range of 100 fM to 100 nM. Specifically, the BP-functionalized sensor exhibits superior dynamic range, higher sensitivity, and lower detection limits for detecting Au@cDNA. The synergistic effect of interfacial sensitization by BP and signal amplification by AuNPs significantly enhances detection performance, providing a promising platform for ultra-sensitive biosensing applications.