TY - JOUR A1 - Ida, Jeunice A1 - Chan, Soo Khim A1 - Glökler, Jörn A1 - Lim, Yee Ying A1 - Choong, Yee Siew A1 - Lim, Theam Soon T1 - G-Quadruplexes as An Alternative Recognition Element in Disease-Related Target Sensing JF - Molecules N2 - G-quadruplexes are made up of guanine-rich RNA and DNA sequences capable of forming noncanonical nucleic acid secondary structures. The base-specific sterical configuration of G-quadruplexes allows the stacked G-tetrads to bind certain planar molecules like hemin (iron (III)-protoporphyrin IX) to regulate enzymatic-like functions such as peroxidase-mimicking activity, hence the use of the term DNAzyme/RNAzyme. This ability has been widely touted as a suitable substitute to conventional enzymatic reporter systems in diagnostics. This review will provide a brief overview of the G-quadruplex architecture as well as the many forms of reporter systems ranging from absorbance to luminescence readouts in various platforms. Furthermore, some challenges and improvements that have been introduced to improve the application of G-quadruplex in diagnostics will be highlighted. As the field of diagnostics has evolved to apply different detection systems, the need for alternative reporter systems such as G-quadruplexes is also paramount. KW - G-quadruplex KW - DNAzyme KW - colorimetric KW - fluorescence KW - luminescence KW - diagnostics Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-11438 SN - 1420-3049 VL - 24 IS - 6 ER - TY - JOUR A1 - Omar, Noorsharmimi A1 - Loh, Qiuting A1 - Tye, Gee Jun A1 - Choong, Yee Siew A1 - Noordin, Rahmah A1 - Glökler, Jörn A1 - Lim, Theam Soon T1 - Development of an Antigen-DNAzyme Based Probe for a Direct Antibody-Antigen Assay Using the Intrinsic DNAzyme Activity of a Daunomycin Aptamer JF - Sensors N2 - G-Quadruplex (G-4) structures are formed when G-rich DNA sequences fold into intra- or intermolecular four-stranded structures in the presence of metal ions. G-4-hemin complexes are often effective peroxidase-mimicking DNAzymes that are applied in many detection systems. This work reports the application of a G-rich daunomycin-specific aptamer for the development of an antibody-antigen detection assay. We investigated the ability of the daunomycin aptamer to efficiently catalyze the hemin-dependent peroxidase activity independent of daunomycin. A reporter probe consisting of biotinylated antigen and daunomycin aptamer coupled to streptavidin gold nanoparticles was successfully used to generate a colorimetric readout. In conclusion, the daunomycin aptamer can function as a robust alternative DNAzyme for the development of colorimetric assays. KW - G-quadruplex KW - DNAzyme KW - gold nanoparticle KW - antibody Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-6267 SN - 1424-8220 VL - 14 IS - 1 SP - 346 EP - 355 ER -