The more common structures used for biosensors: (1) Aptamers; (2) DNAzyme;
(3) Riboswitch and Ribozymes; (4) XNA-based biosensors. Aptamers are single
strand oligomers, both DNA and RNA that can maintain the natural conformation
such as G-quadruplex or hairpin and stem-loop. The aptamer selection and production requires the application of the well established combinatorial SELEX
procedure [29] to obtain nucleic acid probe for a specific ligand.
Fig. 1 a DNA 4WJ (Hollyday Junction PDB 1P54); b RNA 3WJ (PDB 4JIY). The two images
has been obtained using PDB structural visualization tools. The figure shows the biological
assembly of two structure. This presentation gives a more intuitive view of the 3D structure
Fig. 2 Examples of G-quadruplex: a DNA G-quadruplex (PDB code 6GE1) The yellow residues
are modified nucleobase and the green ball are potassium ions; b RNA telomeric G-quadruplex
(PBD code 3MIJ) The yellow molecule is the ligand and the green ball mark the potassium ions
The images have been obtained by UCSF CHIMERA visualization tool (https://www.cgl.ucsf.edu/
chimera/)
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