A highly effective polymerase chain reaction enhancer based on dendrimer-entrapped gold nanoparticles

In molecular biology, polymerase chain reaction (PCR) has played an important role but suffers a general problem of low efficiency and specificity. Development of suitable PCR additives to improve the specificity and efficiency still remains a great challenge. Here we report the use of dendrimer-entrapped gold nanoparticles (Au DENPs) as a novel class of enhancers to improve the specificity and efficiency of PCR. We show that the Au DENPs prepared using amine-terminated generation 5 poly(amidoamine) dendrimers (G5.NH(2)) as templates are much more effective than the same dendrimers without AuNPs entrapped in improving the specificity and efficiency of an error-prone two-round PCR system. With the increase of the molar ratio between Au atom and G5.NH(2) dendrimer in the Au DENPs, the optimum concentration of Au DENPs used to improve the PCR specificity and efficiency is decreased and can be as low as 0.37 nM when the Au atom/G5.NH(2) dendrimer molar ratio reaches 100:1. Our PCR results along with the dynamic light scattering data suggest that unlike the flexible soft dendrimers without NPs entrapped that may display a non-spherical shape when interacting with the PCR components, the Au DENPs with increasing Au atom/dendrimer molar ratio are able to reserve the spherical shape of dendrimers, enabling much more efficient interaction with the PCR components. Therefore, as a NP-based PCR enhancer, both the surface charge and the shape of the particles should be responsible for effective interaction with the PCR components for improving the PCR specificity and efficiency. Furthermore, the used Au DENPs were proved to be stable after the PCR process, enabling them to be potentially used for enhancing different PCR systems.