Covalent Modification of Reduced Graphene Oxide by Means of Diazonium Chemistry and Use as a Drug‐Delivery System

Abstract

Under acidic conditions, reduced graphene oxide (rGO) was functionalized with p-aminobenzoic acid, which formed the diazonium ions through the diazotization with a wet-chemical method. Surfactants or stabilizers were not applied during the diazotization. After the functionalized rGO was treated through mild sonication in aqueous solution, these functionalized rGO sheets were less than two layers, which was determined by atomic force microscopy (AFM) imaging. The water solubility of functionalized rGO after the introduction of polyethyleneimine (PEI) was improved significantly; it was followed by covalent binding of folic acid (FA) molecules to the functionalized rGO to allow us to specifically target CBRH7919 cancer cells by using FA as a receptor. The loading and release behaviors of elsinochrome A (EA) and doxorubicin (DOX) on the functionalized rGO sheets were investigated. The EA loading ratio onto rGO-C(6)H(4)-CO-NH-PEI-NH-CO-FA (abbreviated rGO-PEI-FA, the weight ratio of drug loaded onto rGO-PEI-FA) was approximately 45.56 %, and that of DOX was approximately 28.62 %. It was interesting that the drug release from rGO-PEI-FA was pH- and salt-dependent. The results of cytotoxicity (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and flow cytometry (FCM) assays, as well as cell morphology observations) clearly showed that the concentration of rGO-PEI-FA as the drug-delivery composite should be less than 12.5 mg L(-1). The conjugation of DOX and rGO-PEI-FA can enhance the cancer-cell apoptosis effectively and can also push the cancer cells to the vulnerable G2 phase of the cell cycle, which is most sensitive and susceptible to damage by drugs or radiation.

Long-Term High-Temperature Stability of Functionalized Graphene Oxide Nanoplatelets in Arab-D and API Brine

“…The aminostyrene groups permitted the use of diazonium chemistry [17][18][19][20] for producing covalent attachments of the polymer chain directly to the graphene basal plane. Although the use of diazonium species to covalently decorate the basal plane of graphene is well-established, we believe that the use of a diazonium containing polymer in a 'grafting-to' approach is particularly advantageous in covalently functionalizing graphene with a relatively high number of functional groups.…”

Engineering of carbon based nanomaterials by ring-opening reactions of a reactive azlactone graphene platform

“…The structures of the obtained compounds were supported by spectral and analytical data; in particular the FT-IR spectrum of APDMA shows the strong stretching bands at 2097 cm À1 (vNQNQN), 1818 cm À1 (vCQO), 1652 cm À1 (vCQN) and 1200 cm À1 (vC-O-C) (ESI, † Fig. 6 Thus, the surfaces of G-red were functionalized by attaching a p-(2-propylnyloxy)-benzene moiety using p-(2-propynyloxy)benzamine (5) and sodium nitrite under acid conditions (Scheme 2).The stability of suspensions in water of G-red and G-Alk was investigated; as expected a better dispersibility of G-Alk was observed (ESI, † Fig. The graphene substrate (G-red) was obtained by chemical oxidation of graphite, direct exfoliation of graphite oxide via ultra-sonication to graphene oxide (GO) and reduction with hydrazine under controlled conditions (ESI, † Fig.…”

30 years of advances in functionalization of carbon nanomaterials for biomedical applications: a practical review

“…Zhang, X. et al 150 have developed hybrid materials of graphene with porphyrin, namely, graphenetetraphenylporphyrin (graphene-TPP) and graphenepalladium tetraphenylporphyrin (graphene-PdTPP) 133 Yang et al, 134 Tian et al, 136 Hong et al 141 through a one-pot cycloaddition synthesis route, with potential applications in fluorescence imaging of cells and in sensors. Wei, G. et al 151 have used a wet-chemical diazotization method, to functionalize rGO with p-aminobenzoic acid. After the introduction of PEI and target molecule FA, they were able to load and deliver elsinochrome A (EA) and doxorubicin, which showed synergistic effect of enhanced chemotherapeutic efficacy by arresting cell cycle activity in the G2 phase.…”