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.