In view of preparing effective nitric oxide gas carriers, a fluorinated poly(ethylene glycol) (F-PEG) was non-covalently conjugated with acid-treated graphene oxide (GO) to prepare the composite of F-PEG@GO. When the persistence of NO gas doped on GO and F-PEG@GO was investigated for 3 h, the conserved NO gas decreased from 49.00±7.06 to 2.17±1.36 nmol/mg carrier and from 58.51± 6.02 to 4.58±2.22 nmol/mg carrier, respectively. The adsorption of F-PEG on GO and the doping of NO on GO and F-PEG@GO were declarative by the increase of distance between GO sheets, and the NO-doping was also clarified by infrared absorption and X-ray photoelectron spectroscopies. The anti-bacterial effect was higher for NO-conserved F-PEG@GO than for NO-conserved GO and more effective against Staphylococcus aureus than against Escherichia coli. It is evident that the coating of F-PEG on GO is preferable for advancing the loading efficiency, the stability and the biomedical efficacy of NO gas.
Graphene oxide (GO), single-walled carbon nanohorn (CNHox), and nitrogen-doped CNH (N-CNH) were functionalized with fluorinated poly(ethylene glycol) (F-PEG) and/or with a fluorinated dendrimer (F-DEN) to prepare a series of assembled nanocomposites (GO/F-PEG, CNHox/F-PEG, N-CNH/F-PEG, N-CNH/F-DEN, and N-CNH/F-DEN/F-PEG) that provide effective multisite O 2 reservoirs. In all cases, the O 2 uptake increased with time and saturated after 10−20 min. When graphitic carbons (GO and CNHox) were coated with F-PEG, the O 2 uptake doubled. The O 2 loading was slightly higher in N-CNH compared to CNHox. Notably, coating N-CNH with F-DEN or F-PEG, or with both F-DEN and F-PEG, was more effective. The best performance was obtained with the N-CNH/F-DEN/F-PEG nanocomposite. The O 2 uptake kinetics and mechanisms were analyzed in terms of the Langmuir adsorption equation based on a multibinding site assumption. This allowed the precise determination of multiple oxygen binding sites, including on the graphitic structure and in the dendrimer, F-DEN, and F-PEG. After an initial rapid, relatively limited release, the amount of O 2 trapped in the nanomaterials remained high (>95%). This amount was marginally lower for the functionalized composites, but the oxygen stored was reserved for longer times. Finally, it is shown that these systems can generate singlet oxygen after irradiation by a light-emitting diode, and this production correlates with the amount of O 2 loaded. Thus, it was anticipated that the present nanocomposites hierarchically assembled from components with different characters and complementary affinities for oxygen can be useful as O 2 reservoirs for singlet oxygen generation to kill bacteria and viruses and to perform photodynamic therapy.
Combination therapy for cancer is expected for the synergetic effect of different treatments, and the development of promising carrier materials is demanded for new therapeutics. In this study, nanocomposites including functional nanoparticles (NPs) such as samarium oxide NP for radiotherapy and gadolinium oxide NP as a magnetic resonance imaging agent were synthesized and chemically combined with iron oxide NP-embedded or carbon dot-coating iron oxide NP-embedded carbon nanohorn carriers, where iron oxide NP is a hyperthermia reagent and carbon dot exerts effects on photodynamic/photothermal treatments. These nanocomposites exerted potential for delivery of anticancer drugs (doxorubicin, gemcitabine, and camptothecin) even after being coated with poly(ethylene glycol). The co-delivery of these anticancer drugs played better drug-release efficacy than the independent drug delivery, and the thermal and photothermal procedures enlarged the drug release. Thus, the prepared nanocomposites can be expected as materials to develop advanced medication for combination treatment.
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