Laser-Generated Au-Ag Nanoparticles For Plasmonic Nucleic Acid Sensing

The development of nanoplasmonic sensing approaches for DNA detection based on the localized plasmonic properties of different metallic NPs fabricated by femtosecond laser ablation with an application for synthetic oligonucleotides as specific probes for genetic sequence variations is presented. The planar surface plasmon resonance (SPR) technique has been used to test oligonucleotide probes specific to rpoB genes of Mycobacterium tuberculosis. Optimal experimental conditions providing efficiency of hybridization between immobilized probe and cDNA target and performance of the SPR method were obtained and applied to the nanoplasmonic biosensing based on colloidal nanoparticles. Gold and silver/gold alloy nanoparticles were fabricated by the pure laser ablation method and have shown faster conjugation to thiol-modified DNA and higher stability in hybridization buffer than nanoparticles produced by chemical synthesis. Nanoparticle-enhanced and spectral SPR methods were used to confirm the efficiency of DNA-modified laser-generated gold nanoparticles in biosensing. Numerical estimation shows a higher sensitivity of nanoalloy materials application in dimer aggregate configurations. The described approaches could be proposed as a basis for an optical biosensor for sensitive and real-time detection of nucleic acid samples, for example, nucleotide sequences related to drug-resistant tuberculosis.