Optimization of Parameters of Saline Sodium Citrate Buffer for Stability of Colloidal Gold Nanoparticles Used in DNA Hybridization Biosensor

Background. The use of optical biosensors based on surface plasmon resonance (SPR) spectrometry have long been established as a viable alternative to the traditional molecular biological methods, such as immunostaining or ELISA. Its capacity to perform real-time quantitative measurements is complemented with the possibility for the enhancement of the sensor signal with the use of optically active colloidal nanoparticles. On the other hand, few such nanoparticle-containing DNA biosensors have been developed, owing to poor colloidal stability of nanoparticles in chemical conditions suitable for hybridization of nucleic acid sequences. Objective. This study investigates the possibility of using gold nanoparticles (AuNPs) modified with thiolated oligonucleotides, 6-mercapto-1-hexanol, and lipoic acid as part of a hybridization system for biosensor detection of DNA sequences in order to improve its main analytical characteristics. Methods. A study of the colloidal stability of nanoparticles in SSC (saline sodium citrate) media of different multiplicity before and after modification was carried out in order to select the best environment for the operation of the biosensor system. Aggregation of modified AuNPs was facilitated by their centrifugation, after which pelleted nanoparticles were resuspended and investigated by spectrophotometry. The conclusions regarding the colloidal stability of AuNPs were based on the drop in concentration of colloidal AuNPs after each centrifugation. Results. The possibility of using the studied NPs in biosensor analysis was shown, and 0.1×SSC buffer solution was determined to be the optimal medium for their operational stability. Approbation of the nanoparticle-containing DNA hybridization biosensor based on SPR spectrometry was carried out in 2.0×SSC medium. Conclusions. The prospective use of the studied NPs as components of DNA hybridization systems for the detection of genetic markers has been proven.