Laser-Induced graphene electrodes for highly sensitive detection of DNA hybridization via consecutive cytosines (polyC)-DNA-based electrochemical biosensors

[Display omitted] •Fabrication of a LIG electrode-based consecutive cytosines (polyC)-DNA for electrochemical DNA biosensor.•Cost-effective, amplification-free, and chemical treatment-free solution for carbonized nanomaterial biofunctionalization.•An enhanced response for the target DNA within a LOD down to 57 fM.•High selectivity with good recovery levels in diluted healthy human serum. Numerous carbon-based biosensors issued mechanical exfoliation, epitaxial growth, reduced graphene oxide, and chemical vapor deposition have been investigated for highly sensitive and specific detection of DNA. As a promising route for designing electrochemical biosensor-based flexible substrates, the laser-induced graphene technique, which provides a cheap, technologically simple, and highly robust sensing platform, has been widely adopted. However, DNA-based biosensors' efficiency is strongly dependent on how DNA probes are tethered to the nanomaterials. In view of this, poly-cytosine (poly-C) DNA has shown outstanding adsorption to multiple inorganic nanomaterials, including gold (Au), zinc oxide (ZnO), tungsten disulfide (WS2), graphene oxide (GO), and graphene. In this work, a poly C(15)-tailed diblock DNA probe is used to anchor to carbonized working electrode issued laser-induced method. Meanwhile, the second block modified with ferrocene (Fc) derivatives is lifted at the surface for DNA sequence recognition. Following this strategy, the developed biosensor leads to a limit of detection (LOD) of 57 fM, which was superior or comparable to some previously reported methods. Moreover, the proposed electrochemical DNA biosensor exhibits high specificity in differentiating the complementary DNA from non-complementary DNA (ncDNA), and mismatched DNAs (MM-DNA) sequences. Finally, the easily constructed laser-induced graphene electrode biosensor showed an ability to detect DNA in human serum as a complex environment, making our approach a promising avenue for disease diagnosis.