DNA methylation is epigenetic events commonly occurs in mammalian genome starting from formation of embryo to the end of life. Especially, hypermethylation in tumor suppressor genes, corresponds the cancer growth and detection of DNA methylation in these genes crucial for the diagnosis of cancer. Water soluble polythiophenes are frequently used for the detection of biomolecules through the optoelectronic properties. In this study, detection of DNA methylation of multiple tumor suppressor p16INK4A gene via polythiophene based optical sensor was achieved. Newly designed, synthesized and characterized poly(1-(3-((4-methylthiophen-3-yl) oxy) propyl)-1,4- diazabicyclo [2.2.2] octan-1-ium bromide) was used during characterization of DNA sequences and detection of DNA methylation. The target sequence position is +137 to +156 in p16INK4A gene which have three potential CG dinucleotide to be methylated. Detection of DNA methylation based on sodium bisulfite treatment, complementary sequence of unmethylated ssDNA and the conformational change of water soluble polythiophene. In our fluorometric analysis, unmethylated sequence/complementary successfully hybridized and dsDNA Io/I ratio is under the 1.40 while the methylated sequence/complementary hybridization failed due to different base content and remain as ssDNA and, Io/I ratio is higher than 1,60. The novelty of work is detection mechanism is PCR and FRET free with a range of 300 ng to 700 ng sample requirement. Characterization of homopurines, homopyrimidines, methylated and unmethylated sequence with cationic polythiophenes also accomplished. PolyG (10), polyG (20) and polyA (10) yielded a no signal in UV-VIS region while the polyA (20) yielded a 100 nm red shift. Furthermore, PolyC (10), PolyC (20), PolyT (10), PolyT (20) yielded three vibrionic peaks at 505 nm, 545 nm and 595 nm with different intensities and unique isosbestic points. All 10 bases long homopyrimidine and homopurine have a unique quencher character with cationic polythiophene. Lastly, conformational change of polythiophene investigated with computational methods and heptamer used as a model.