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Issue 1, 2014
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“Turn-on-off-on” fluorescence switching of quantum dots–cationic porphyrin nanohybrid: a sensor for DNA

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Abstract

In this article, we describe a new platform for probing double stranded DNA (dsDNA) by tracing the “on-off-on” fluorescence signals of quantum dots–cationic porphyrin utilizing fluorescence and synchronous fluorescence measurements. Electrostatic interaction between the negatively charged thioglycolic acid capped CdTe quantum dots (CdTe-TGA QDs) and positively charged porphyrin surfaces leads to drastic quenching (turning off) of the donor by an effective electron transfer process. Interestingly, after the addition of calf thymus DNA (CtDNA), the porphyrins peel off from the quantum dot surface and bind to dsDNA, resulting in the restoration of fluorescence intensity of quantum dots (turning on). Consequently, this can be utilized for the selective sensing of dsDNA via optical responses. Experimental results show that the increase in fluorescence intensity is proportional to the concentration of CtDNA within the range of 6.5 × 10−9 M to 29.6 × 10−8 M under the optimized experimental conditions. Furthermore, the peel off mechanism was confirmed by atomic force measurement.

Graphical abstract: “Turn-on-off-on” fluorescence switching of quantum dots–cationic porphyrin nanohybrid: a sensor for DNA

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Publication details

The article was received on 03 Oct 2013, accepted on 08 Oct 2013 and first published on 08 Oct 2013


Article type: Paper
DOI: 10.1039/C3AN01871G
Citation: Analyst, 2014,139, 225-234
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    “Turn-on-off-on” fluorescence switching of quantum dots–cationic porphyrin nanohybrid: a sensor for DNA

    E. Vaishnavi and R. Renganathan, Analyst, 2014, 139, 225
    DOI: 10.1039/C3AN01871G

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