For decades, the detection of nucleic acids and their interactions at low abundances has been a challenging task. Present nucleic acid diagnostics are primarily based on enzymatic reactions including sequencing, polymerase-chain reaction and microarrays. However, the use of enzymatic amplification interferes with the initial biomolecular system, is limited to in vitro assays, often time consuming and rather expensive. Therefore, there is interest in new amplification-free detection methods. A tremendous progress has been made in fluorescence based optical detection of biomolecules. In this work, we aimed at developing efficient tools for amplification-free nucleic acid detection. The result of simple and inexpensive polymerization in the presence of fluorescent dyes and additional functionalization reagents was ultra-bright fluorescent nanoparticles modified with additional groups for bioconjugation.