Modification Effect of Nano-Graphene Oxide on Properties and Structure of Polysulfone Ultrafiltration Membrane

In order to improve the purification properties of polysulfone (PSF) ultrafiltration membranes (UFM), nano-graphene oxide (nano-GO) was taken as modifier, and the physical blending process was adopted in our experiment. The microstructure, surface morphology and functional groups of modified UFM have been characterized respectively by scanning electron microscopy, atomic force microscopy and Fourier transform infrared spectroscopy, and the static contact angle between the membrane surface and the water droplet has also been detected to show the change of its hydrophilicity. Through experiments, it has been found that modified UFM has larger and more developed finger micro-pores, and there exist a large number of -OH groups on its surface, and also its hydrophilicity has been enhanced. The result of the experiments show that the modified UFM may keep rejection above 97% and its water flux can be reached at about 219.1 L/(m2·h) under pressure of 1 bar if 0.4 wt% of nano-GO was added. Additionally, the nano-GO can increase the flux recovery radio (FRR) of the membranes, and the maximum FRR was observed as 74.4% if 0.3 wt% of nano-GO was appended.

Poly(ethylene glycol) conjugated nano-graphene oxide for photodynamic therapy

A novel methoxy-poly(ethylene glycol) modified nano-graphene oxide(NGO-mPEG) was designed and synthesized as a photosensitizer(PS) carrier for photodynamic therapy of cancer.NGO with a size below 200 nm was prepared using a modified Hummers' method.NGO was observed by AFM to exhibit a structure with single-layer graphene oxide sheets down to a few nanometers in height.Hydrophilic mPEG conjugation of NGO(NGO-mPEG) was found to enhance solubility in cell culture media.No apparent cytotoxicity of the NGO-mPEG was observed towards MCF-7 carcinoma cell line.Zinc phthalocyanine(ZnPc),a photosensitizer for photodynamic therapy,was loaded in the NGO-PEG through π-π stacking and hydrophobic interactions,with the drug loading efficiency up to 14 wt%.Hydrophobic ZnPc was internalized in MCF-7 cells,exhibiting a pronounced phototoxicity in the cells under Xe light irradiation.The results indicate a great potential of NGO-mPEG for photodynamic therapy of cancer.

Let-7i miRNA and platinum loaded nano-graphene oxide platform for detection/reversion of drug resistance and synergetic chemical-photothermal inhibition of cancer cell

The drug resistance of chemotherapy is a major challenge to overcome for antineoplastic agents and the reverse of drug resistant is essential for cancer therapy. Herein, we developed a drug delivery system which can simultaneously detect/reverse the drug resistance and perform synergetic treatment of cancer. In this work, we integrated cyanine5(Cy5) modified mi RNA(let-7 i)(Cy5-mi RNA) and platinum onto nano-graphene oxide(NGO)(30-50 nm) platform to achieve simultaneously detection/reversion of drug resistance and synergetic treatment of cisplatin resistant SKOV3 cells(SKOV3 DDP cells). The Cy5-mi RNA adsorbed on NGO could selectively bind the drug resistance related m RNA follow by suppress the expression of drug resistance m RNA, and the binding simultaneously induced the release of Cy5-mi RNA from the NGO, thus the fluorescence signal of Cy5 recovered and could be used for drug resistance monitoring.Moreover, the mi RNA suppressed the Cyclin D1 protein expressions thus reversed the drug resistance. The loaded platinum(Ⅳ)(Pt(Ⅳ)) was converted to the therapeutic platinum(Ⅱ)(Pt(Ⅱ)) in both tumor acidic and reductive environment responsive behavior. NGO furtherly performed photothermal therapy under near infrared(NIR) laser irradiation and enhanced the therapeutic effect. All in all, this nanoplatform realized detection/reversion of the drug resistance as well as synergetic chemical-photothermal treatment of ovarian cancer cells, which holds great promise in the treatment of drug resistant cancer cells.

Theoretical Studies on the Electronic Structure of Nano-graphenes for Applications in Nonlinear Optics

In this work,azulene is introduced into nano-graphene with coronene center to enhance the second-order nonlinear optical(NLO)properties.The sum-over-states(SOS)model based calculations demonstrate that dipolar contributions are larger than octupolar contributions to the static first hyperpolarizability(〈β0〉)in most nano-graphenes except those with high symmetry(e.g.,a C2v nano-graphene has octupolar contributionsΦJ=3 up to 59.0%of the〈β0〉).Nano-graphenes containing two parallel orientating azulenes(i.e.,Out-P and Out-Ps)have large dipole moments,while their ground state is triplet.Introducing B/N/BN atoms into the positions with a high spin density transfers the ground state of Out-P and Out-Ps to closed-shell singlet,and the Out-Ps-2N has a large〈β0〉of 1621.67×10−30 esu.Further addition of an electron donor(NH2)at the pentagon end enhances the〈β0〉to 1906.22×10−30 esu.The two-dimensional second-order NLO spectra predicted by using the SOS model find strong sum frequency generations and difference frequency generations,especially in the near-infrared and visible regions.The strategies to stabilize the electronic structure and improve the NLO properties of azulene-defect carbon nanomaterials are proposed,and those strategies to engineer nano-graphenes to be semiconducting while maintaining theπ-framework are exten-dable to other similar systems.

Functionalized nanographene oxide/PEG/rhodamine B/gold nanocomposite for electrochemical determination of glucose

Diabetes,one of the most serious metabolism diseases,has continually plagued human beings so that timely monitored blood glucose level is very necessary.Gold nanoparticles(Au NPs)have been considered as potential substitutes for non-enzymatic sensors,due to their unusual physicochemical property and efficient catalytic activity.Herein,we prepared a facial platform for Au NPs to maintain good dispersity and inherent physicochemical property.In this special platform(SH-n GO-PEG-Rh B),nanographene oxide(n GO)was employed as an ideal base,which provided adequate carboxyls for conjugating with poly(ethylene glycol)(PEG),and enough epoxy groups for thiol active site.A functional dye(rhodamine B)with preferable fluorescence properties was also introduced into this platform.Au NPs were then aptly in situ grown on the platform via reduction of HAuCl_(4) under mild conditions,providing Au NPs@SHn GO-PEG-Rh B.The nanocomposite was cast on a glassy carbon electrode(GCE)conveniently,yielding GCE/Au NPs@SH-n GO-PEG-Rh B.Reasonably,as shown by cyclic voltammetry(CV)and ready-state amperometry,GCE/Au NPs@SH-n GO-PEG-Rh B was capable of electrochemical determination of glucose so as to provide an efficient sensor for glucose determination with dye tracer.