Carbon dots assisted formation of DNA hydrogel for sustained release of drug

The construction of DNA-carbon dot (CD) hybrid hydrogel for targeted and sustained release of drug molecules is reported here. Amine functionalized carbon dots were conjugated to 5'-phosphate termini of Cytosine (C) rich ssDNA by phosphoramidate linkage. As a prototype, chemotherapeutic drug Doxorubicin (Dox) was loaded and enclosed in hydrogel that acts as a container for sustained release of the drug. Apart from acting as a cross linker for network formation, CDs also participate in encapsulating the drug by electrostatic interaction along with DNA. Moreover, photophysical properties of CD potentially enable tracking of hydrogel dissolution and drug cargo loading in hydrogel. The visually detectable solgel transition of CD-DNA hybrid hydrogel was achieved by varying the pH of the solution from alkaline to neutral. The in vitro time and pH dependent release profile of the drug from hydrogel was studied. While hydrogel was found to be stable for a month at normal physiological pH, complete dissolution and sustained release of the drug molecules were achieved over 10-11 days in acidic pH, relevant to tumor microenvironxnent. The cell viability assay performed on HeLa cells shows their effective slow killing in presence of Dox loaded hydrogel owing to favorable acidic pH for hydrogel disruption. (C) 2016 Elsevier Ltd. All rights'reserved.