I was trying to compare the fluorescence emission spectra of Graphene quantum dots (GQDs), peptide-functionalized GQDs (pGQDs) and DNA-pGQDs at same excitation wavelength. Emission peak for GQDs, pGQDs, and DNA-pGQDs was observed at 446 nm, 453 nm (red shited by 7 nm) and 412 nm (blue shifted by 34 nm) respectively. Also, intensity increased significantly after addition of DNA to the pGQDs complex. One reason could be change in size of the GQDs since the peptide that I used is graphene binding peptide. The increase in intensity with the addition of DNA could be decrease in core size of the GQDs. Could there be any better explanation?
The change in shift indicates the alteration in the properties of your GQD. blue shift means GQD property is reduced slightly and red indicates improvement in the property.
The other reason may be due to the color change in your GQD when you add DNA and peptide to the GQD.
@ Sanjay, are you referring the fluorescence property of GQDs by alteration in properties? But with the addition of the DNA increase in intensity as well as blue shift in emission maximum was observed.
I agree change in color could be one of the reasons. I am thinking increase in intensity could be due to decrease in core size of the GQDs upon binding of DNA on the surface of pGQDs. Does that make sense to you?
@ bedanga, The increase in the intensity of the emission peak is either due to increase in the particle size after adding DNA or may be due to aggregation. The change in shift is purely a property change only.
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