title: Fluorescent graphene oxide via polymer grafting: an efficient nanocarrier for both hydrophilic and hydrophobic drugs.
abstract: Functionalized graphene-based drug delivery vehicles have conquered a significant position because functionalization improves its biocompatibility and stability in cell medium, leaving sufficient graphitic basal plane for drug loading through π-π stacking. In this study, poly(N-isopropylacrylamide) (PNIPAM) is covalently grafted from the surface of graphene oxide (GO) via a facile, eco-friendly and an easy procedure of free radical polymerization (FRP) using ammonium persulfate initiator. Various spectroscopic and microscopic studies confirm the successful grafting of PNIPAM from GO surface. PNIPAM-grafted GO (GPNM) exhibits enhanced thermal stability, improved dispersibility both in aqueous and cell medium, and better biocompatibility and cell viability compared to GO. Interestingly, GPNM displays an exciting fluorescence property in aqueous medium, which is a hike of intensity at 36 °C due to the lower critical solution temperature (LCST) of PNIPAM chains (32 °C). Moreover both hydrophilic (doxorubicin (DOX)) and hydrophobic (indomethacin (IMC)) drugs loaded on the surface of GPNM hybrid exhibits its efficacy as an efficient carrier for both types of drugs. Cellular uptakes of free DOX and DOX-loaded GPNM (GPNM-DOX) are evidenced both from optical and fluorescence imaging of live cells, and the efficiency of drug is significantly improved in the loaded system. The release of DOX from GPNM-DOX was achieved at pH 4, relevant to the environment of cancer cells. The pH-triggered release of hydrophobic drug was also studied using UV-vis spectroscopy via alginate encapsulation, showing a great enhancement at pH = 7.4. The IMC is also found to be released by human serum albumin using dialysis technique. The GPNM nanomaterial shows the property of simultaneous loading of DOX and IMC as well as pH-triggered simultaneous release of both of the drugs.
authors.affiliation: Polymer Science Unit, Indian Association for the Cultivation of Science , Jadavpur, Kolkata 700 032, India.
authors.forename: Aniruddha
authors.initials: A
authors.lastname: Kundu
authors.forename: Sudipta
authors.initials: S
authors.lastname: Nandi
authors.forename: Pradip
authors.initials: P
authors.lastname: Das
authors.forename: Arun K
authors.initials: AK
authors.lastname: Nandi
mesh_terms: D004317:Doxorubicin / Q000737:chemistry* / Q000494:pharmacology; D004337:Drug Carriers / Q000138:chemical synthesis / Q000737:chemistry*; D016503:Drug Delivery Systems / Q000295:instrumentation*; D005453:Fluorescence; D006108:Graphite / Q000737:chemistry*; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D007213:Indomethacin / Q000737:chemistry* / Q000494:pharmacology; D053758:Nanoparticles / Q000737:chemistry; D010087:Oxides / Q000737:chemistry*; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry*
chemical_list: D004337:Drug Carriers; D010087:Oxides; D011108:Polymers; D006108:Graphite; D004317:Doxorubicin; D007213:Indomethacin
keywords: cellular uptake; doxorubicin; drug delivery; fluorescence; free radical polymerization