Perpustakaan Digital ITB

Carbon dots (CDS) are materials that gave been widely explored because of its optical ability as well as its ability to be conjugated with another molecules such as protein and DNA. Until now, CDS has been developed and applied well for bioimaging and as biosensor. Previous studies have proved the effectivity of CDS with additional pyrrole as raw material as an antivirus for SARS-CoV2 as well as immunosensor for COVID-19. However, application of conjugated CDS with DNA as biosensor has not been reported. Therefore, we tested and modified some methods to conjugate CDS with DNA in this research to develop a DNA probe with FRET system. The target of the DNA probe synthesized was dengue virus genome, the virus responsible for the endemic dengue fever in Indonesia. Four methods were designed, modified, and tested with combining reactant such as EDC, NHS, and imidazole to facilitate the conjugation reaction as well as combining the concentration of reactants used. The conjugation process was confirmed by measuring the change in CDS’ fluorescence, FTIR test to confirm the reaction between the surface groups of CDS and ssDNA, and fluorescence spectrum check. Then, the probes were added with graphene oxide (GO), a material with the ability to quench fluorescence emission, so that DNA probes with FRET system were obtained. The probes activity was observed by measuring the fluorescence recovered after the probes were incubated with control solutes containing plasmid with part of dengue virus genome. The fluorescence of the probes can be restored due to the stronger affinity of target sequence for the probes than for GO as the quencher and cause GO to be released from the probes. The results showed a similar trend in fluorescence fluctuation across four conjugation methods tested where the fluorescence of CDS was increased after the reactants were added and then decreased after conjugation with DNA and purification. Moreover, fluorescence recovery after incubation was observed in two of the four probes synthesized, in which one used EDC/NHS and other used EDC/imidazole for conjugation. Around 55,86% and 38,42% (p<0,001; p<0,05) fluorescence were recovered for the two probes. The result showed that the probes synthesized have potential to be applied as a biosensor for diagnostic test.