MXene Ti₃C₂-AuNPs based all-fiber device for alkane degradation genes detection

MXene Ti 3 C 2 has emerged as a promising biosensing material due to the high surface area, excellent biocompatibility, tunable functional groups (-F, O, -OH), and outstanding electrical conductivity, effectively addressing issues such as low sensitivity and inadequate biocompatibility in sensors. This work, MXene Ti 3 C 2 -AuNPs are synthesized as functional materials through a one-step synthesis method. We propose the first all-fiber biosensor featuring a laterally offset SMF-MMF-SMF-MMF-SMF (SMSMS) interferometric structure functionalized with MXene Ti 3 C 2 -AuNPs as the substrate of the biosensor sensor device, for the detection of the alkane degradation (ALK) gene, to the best of our knowledge. The biosensor enables in-situ target DNA (tDNA) detection across 1 fM to 1 μM concentrations based on this nanoengineered interface, demonstrating 1755.95 nm/RIU sensitivity and a 1 fM limit of detection (LOD) – Two orders of magnitude lower than conventional optical DNA sensors (μM-level). The sensor exhibits a wavelength shift of 1.23 nm in response to complementary DNA, which is 8.2 times greater than that for non-complementary DNA, with a maximum wavelength shift error of 0.11 nm across three repeated experiments and a shift within 0.1 nm over 7 days for sensors with attached functional MXene Ti 3 C 2 , demonstrating excellent specificity, stability, and reproducibility. These advantages render the fiber optic device coated with MXene Ti 3 C 2 -AuNPs an effective solution for ALK gene monitoring and broaden its applicability for ultra-trace DNA detection in environmental and biomedical contexts