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Improving the specificity and efficiency of polymerase chain reaction using polyethyleneimine-based derivatives and nanocomposites

Weiwei Tong, Xueyan Cao, Shihui Wen, Xiangyang Shi*

 

Abstract: Polymerase chain reaction (PCR) has been identified as a fundamental technique in molecular biology and clinical medicine. Improvements of the specificity and efficiency of PCR are always required and the understanding of the PCR enhancing mechanism still remains a great challenge. Here we report the use of branched polyethyleneimine (PEI)-based derivatives and nanocomposites as a novel class of enhancing reagents to improve the specificity and efficiency of PCR. We show that the surface charge polarity of PEI and PEI derivatives plays a major role in their effectiveness to improve the PCR specificity and efficiency. Positively charged amine-terminated pristine PEI, partially (50%) acetylated PEI (PEI-Ac50), and completely acetylated PEI (PEI-Ac) are able to improve the PCR efficiency and specificity with an optimum concentration order of PEI < PEI-Ac50 < PEI-Ac, whereas negatively charged carboxyl-terminated PEI (PEI-SAH) and neutralized PEI modified with both PEG and acetylation (PEI-PEG-Ac) are unable to improve the PCR specificity and efficiency with the concentrations of 3 orders of magnitude more than that of PEI. In addition, multiwalled carbon nanotubes (MWCNTs) modified with PEI is also able to improve the PCR specificity and efficiency with an optimum concentration much less than that of the MWCNTs without PEI modification. Our data clearly suggests that the PCR enhancing effect is primarily based on the interaction between the PCR components and the PEI derivatives or PEI-based nanocomposites, where electrostatic interaction should play a major role to locally concentrate the PCR components on the backbones of the branched PEI or PEI-based nanocomposites, enabling enhanced PCR specificity and efficiency.

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