Nucleotides are essential biomolecules involved in all cellular processes as building blocks of nucleic acids, energy storage, cellular communication mediators and cofactors for many enzymatic reactions. Furthermore, nucleotide analogues have a broad range of applications in molecular biology and medicine. As examples, modified nucleotides are used to label nucleic acids in PCR , for fluorescent in situ hybridization (FISH) or microarray applications. In addition, they improve nuclease stability of aptamers and small interfering RNAs. The importance of nucleoside 5'-triphosphates (NTPs) is also evident in mRNA vaccines, which have become increasingly important in the current Corona pandemic. By incorporating modified NTPs such as N1-methylpseudouridine triphosphates or pseudouridine triphosphates into therapeutic mRNAs significantly less activation of the innate immune response compared to uridine is induced. In addition, there is evidence that modified mRNA is translated more efficiently than unmodified mRNA.