Detection of KRAS mutation by combination of polymerase chain reaction (PCR) and EIS sensor with new amino group functionalization

A capacitive electrolyte-insulator-semiconductor structure was introduced to quantify and distinguish point mutation from the corresponding PCR product of KRAS gene. Si₃N₄ surface with remote NH₃ plasma is proposed to form amino group for DNA probe immobilization. The sensing response was investigated by capacitance-voltage measurement. A linear relationship was found between the reference voltage and DNA concentration from 10^-6 to 10^-9 M. Non-complementary DNA was used for specificity testing, no DNA hybridized with DNA probes and the specificity of EIS structure with NH₃ treatment was confirmed. Compared with APTES silanization and NH₃ plasma treatment, the sample with NH₃ plasma treatment reveal excellent selectivity and specificity, even in the presence of non-complementary DNA. The NH₃ plasma treatment provided suitable method which compatible CMOS technology and could be improved accuracy of bio-sensing in clinical diagnosis.