Noninvasive Prenatal Genetic Screening of Cell-Free Fetal DNA for Early Prediction of β-Thalassemia Using Fiber Optic Nanogold-Linked Sorbent Assay

β-Thalassemia is a prevalent type of severe inherited chronic anemia, primarily identified in developing countries. The identification of single nucleotide polymorphisms (SNPs) plays a vital role in the early diagnosis of genetic diseases. Here, we reported the development of an amplification-free fiber optic nanogold-linked sorbent assay method using a fiber optic particle plasmon resonance (FOPPR) biosensor for rapid and ultrasensitive detection of SNPs. Herein, MutS protein was selected as the biorecognition capture probe and immobilized on the sensing region to capture the target mutant DNA, which was hybridized with a single-base mismatched single-stranded DNA labeled by a gold nanoparticle (AuNP). The AuNP acts as a signaling agent to be detected by the FOPPR biosensor when it is bound on the fiber core surface. The method effectively differentiates mismatched double-stranded DNA by MutS protein from perfectly matched/complementary dsDNA. It exhibits an impressively low detection limit for the detection of SNPs at approximately 10^-16 M using low-cost sensor chips and devices. By determination of the ratio of mutant DNA to normal DNA in cell-free genomic DNA from blood samples, this method is promising for diagnosing β-thalassemia in fetuses without invasive testing techniques.