High-sensitive colorimetric biosensing of PIK3CA gene mutation based on mismatched ligation-triggered cascade strand displacement amplification

The development of highly sensitive assay for low abundance cancer-related gene mutation is significant for early diagnosis and personalized medicine. In this work, we proposed a novel colorimetric strategy for sensitive and specific determination of PIK3CAH1047R gene mutation by combining mismatched ligation-triggered cascade strand displacement amplification (SDA) with G-quadruplex/hemin DNAzyme-catalyzed colorimetric biosensing. Mismatched base and mutation complementary location of ligation probes were detailedly optimized to obtain superior capacity for PIK3CAH1047R mutation determination. The mismatched ligation system selectively triggered downstream cascade SDA to produce a great abundance of G-quadruplex sequences. Subsequently, the numerous G-quadruplexes could combine with hemin to form G-quadruplex/hemin DNAzymes, catalyzing a colorimetric reaction for mutation detection. Based on this mismatched ligation-triggered cascade SDA, the developed method showed admirable capability for mutation determination and high-efficiency for signal amplification. The designed biosensing strategy could detect as low as 0.2% PIK3CAH1047R mutation. In addition, this biosensing strategy could be scalable for the analysis of low abundance mutation gene spiked into human serum samples. Thus, this colorimetric biosensor might become a potential alternative tool for genetic analysis and clinical molecular diagnostics.