Interaction of Carbon nanoparticles with lipid bilayers

Abstract

We herein synthesized differently emissive carbon dots (CDs) and studied their interaction with DMPC lipid bilayer membrane. We synthesized the CDs via hydrothermal method using three isomers of henylenediamine (PDA). The synthesized oCD, mCD and pCD, from the precursors oPDA, mPDA, pPDA, respectively were of the sizes around 2-6 nm. These CDs were characterized by UV-Visible absorption spectra, FT-IR spectroscopy and Atomic Force Microscopy (AFM). We found that the synthesized CDs were fluorescent in nature and we confirmed this by steady-state and time-resolved fluorescence spectroscopy. These oCD, mCD and pCDs emit yellow, green and red colors, respectively under single-wavelength UV irradiation (λ= 365 nm). Further, we studied the utility of CD as a probe for bilayer dynamics and the efficiency of CDs as fluorescent acceptors. We established a FRET pair between the donor lipid-PRODAN and the acceptor CDs. We observed that the different CDs synthesized from the isomers of PDA interact with lipid membrane in a different manner. The oCDs were observed to interact more efficiently than mCD and pCDs. The spectroscopic and imaging studies reveal that the oCDs are embedded inside the lipid bilayers, whereas mCD and pCDs induce aggregation in the bilayer membrane by being located on the interfacial region. These observations are attributed to the isomeric precursors and their hydration features and further to the different location of the CDs in the bilayer membrane. Therefore, among all the three CDs, oCDs are potential candidates for bioimaging applications.