A Novel Fluorescence Nanobiosensor based on Modified Graphene Quantum dots-HTAB for Early Detection of Fetal Sexuality with Cell Free Fetal DNA.

Recently, prenatal diagnosis with non-invasive insight is a progressive approach in clinical medicine to prevent the birth of infants with genetic abnormalities. Cell free fetal DNA (cffDNA) makes up approximately 3-6% of the bare DNA in the mother's bloodstream which is produced during pregnancy and can be used to detect fetal sex and disease in the early stages. SRY is a gene located on the chromosome Y which determines the sex of male infants. In this work, a new nanobiosensor based on the fluorescence property of r-GQD@HTAB (reduced graphene quantum dots modified with hexadecyl trimethyl ammonium bromide) was fabricated that can identify the SRY gene in cffDNA with high sensitivity and specificity. A detection limit of 0.082 nM and the linear response range of 0.16-1.5 nM was obtained for the method. It was able to discriminate the target sequence with high specificity from the non-target sequences. This biosensor includes a new graphene quantum dot modified with a surfactant, HTAB which leads to high fluorescence emission of it and then more precise differentiation between ssDNA and DsDNA in a solution. In conclusion, it provides a novel analytical tool for detection of small amount of DNA and fetal sex and genetic diseases in early stage with prenatal and noninvasive tests and applicable for clinical use.