Improving the performance of a photonic PCR system using TiO2 nanoparticles

Nucleic acid amplification using polymerase chain reaction (PCR) method has been widely used in different fields such as agricultural science, medicine, pathogen identification, and forensics to name a few. Today, it seems inevitable to have a robust, simple PCR system for diagnostics at the point-of-care (POC) level. Many photonic PCR systems have been proposed in the literature that benefit from plasmonic photothermal heating to achieve the common PCR thermal cycling. However, non-homogeneous temperature distribution is a challenge in some of them. In the present work, to achieve more efficient gene amplification, the effect of adding TiO2 nanoparticles has been investigated in a photonic PCR benefiting from plasmonic photothermal heating. The system enjoys higher heating and cooling rates than those of conventional PCR systems while having much lower energy consumption. The average heating and cooling rates are 4.44 °C/s and 2.65 °C/s, respectively. The system demonstrates acceptable temperature stability and accuracy with negligible deviation from the set points. Furthermore, the system is capable of amplifying eight gene samples simultaneously which makes it a viable choice for POC diagnostics. A part of the Alcohol Oxidase gene has been amplified using the plasmonic thermal cycler. It is demonstrated that adding TiO2 nanoparticles with a proper concentration to the sample provides a more specific band that can be ascribed to more homogeneous temperature distribution owing to enhanced thermal conductivity. The best amplification of the target gene has been achieved with a concentration of 0.4 nM of nanoparticles.