The present invention relates to a novel integrated PCR-free signal amplification polynucleotide detection system which combines a specific receptor, an optical transducer, and an amplification mechanism. This novel detection system is based on different electrostatic interactions and confirmations between a cationic polythiophene (i.e., polymer 1) and single-stranded or double-stranded polynucleotides (such as ss-DNA or ds-DNA), and the efficient energy transfer between the triplex (complexation between the cationic polythiophene and ds-DNA) and neighboring fluorophores attached to ss-DNA or ds-DNA probes. It is to be understood that in the case of ss-DNA, triplex formation occurs via the hybridization of complementary ss-DNA strands, combined with complexation and with the cationic polythiophene. The present detection system allows for the detection of single nucleotide polymorphisms (SNPs) from samples in only a few minutes, without the need for nucleic acid amplification.