Polydopamine-reduced Graphene Oxide Research Articles

A highly sensitive and selective electrochemical sensor based on polydopamine functionalized graphene and molecularly imprinted polymer for the 2,4-dichlorophenol recognition and detection

In this work, a sensitive and selective electrochemical sensor based on polydopamine-reduced graphene oxide (PDA-rGO) and molecular imprinted polymers (MIP) modified glassy carbon electrode for detection of 2,4-DCP was fabricated. The PDA-rGO was obtained through the auto polymerization of dopamine in graphene oxide solution at an alkaline environment. The MIP film was performed on the surface of the PDA-rGO modified electrode by electropolymerization the monomer of o-phenylenediamine (o-PD) with the template of 2,4-dichlorophenol (2,4-DCP). The bare hydroxyl and benzene rings of PDA-rGO could attract positive charged o-PD and provide π-π stacking effect with o-PD and 2,4-dichlorophenol, which made the compact imprinted film and more imprinted sites. The Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were used to character the MIP and NIP modified electrode in the presence of [Fe(CN)6]3-/[Fe(CN)6]4- as a probe for signal transduction. The relative current intensity of ferro/ferricyanide decreased linearly with increasing concentration of 2,4-DCP with a detection limit of 0.8 nM (S/N = 3). The MIP sensor had a much higher affinity towards 2,4-DCP than other analogues. The proposed method was successfully applied for the determination of 2,4-DCP in real water samples.

Dopamine constructing composite of Ni(HCO3)2-polydopamine-reduced graphene oxide for high performance electrode in hybrid supercapacitors

High performances, cost-effectiveness, and facile preparation of electrode materials are of utmost importance for supercapacitors in practical applications. Herein, Ni(HCO3)2 nanoparticles (NPs) of low cost and environmental friendliness were embedded into polydopamine-reduced graphene oxide (PDA-RGO) networks via cost-effective hydrothermal route. It is shown the conducting PDA can uniformly distributes and robustly immobilizes Ni(HCO3)2 NPs in the nanocomposite while the ionic channels are improved for electrolyte access. Consequently, the as-prepared Ni(HCO3)2-PDA-RGO composite offers the high Faradaic capacity of 870 C g−1 at 0.5 A g−1 and moderate rate capability. Furthermore, the assembled Ni(HCO3)2-PDA-RGO//activated carbon hybrid supercapacitor (HSC) delivers a specific capacity of 192 C g−1 at 0.5 A g−1 within operation voltage window of 1.7 V. The maximum energy density of the HSC reaches to 45.3 Wh kg−1 at a power density of 425 W kg−1, and the initial specific capacity maintains 90.5% after 3000 successive charge-discharge cycles. The high energy density and good cycleability certify the potential of the ternary Ni(HCO3)2-PDA-RGO composite in efficient and long lifetime energy storage systems.

Tumor targeting dual stimuli responsive controllable release nanoplatform based on DNA-conjugated reduced graphene oxide for chemo-photothermal synergetic cancer therapy.

In this research, a novel tumor targeting dual stimuli responsive nanoplatform was fabricated for the controllable delivery and release of a drug to realize chemo-photothermal synergetic cancer therapy by integrating a DNA aptamer with polydopamine reduced graphene oxide (rGO-PDA) nanosheets. The rGO-PDA nanosheets simultaneously acted as a near-infrared radiation (NIR) photothermal agent to generate hyperthermia for photothermal therapy and a nano-carrier for loading doxorubicin (DOX), and the specially designed DNA aptamer served as a supplementary carrier for DOX loading as well as targeting moiety/gatekeeper for specific cellular recognition and controllable release of DOX. The proposed nanoplatform possessed a good targeting ability, remarkable photothermal conversion ability and intelligent drug release with both pH and photothermal heating dual stimuli response. The nanoplatform was successfully used to selectively deliver DOX to protein tyrosine kinase 7 over-expressing cancer cells with a loading capacity of 1.56 mg mg-1 and controllable drug release, which responded to both acidic intracellular environments and NIR irradiation. The combination of the dual stimuli responsive controllable release and the dual nanocarrier for drug loading results in efficient chemo-photothermal synergetic therapy and holds great potential for multimodal cancer therapy.

Synthesis of lignin-based polyurethane/graphene oxide foam and its application as an absorbent for oil spill clean-ups and recovery

Superhydrophobic and superoleophilic foam-like materials are attracting significant interest as promising absorbent for oil spill clean-up from water bodies. In this work, we report the synthesis of lignin based polyurethane (LPU) foam and its surface modification to form a superhydrophobic and superoleophilic sorbent, for use in spill clean-ups. The interior matrix of the LPU foam substrate was grafted with adhesive polydopamine-reduced graphene oxide (rGO) and octadecylamine (ODA), which reacted to transform the LPU foam skeleton to a superhydrophobic and superoleophilic 3-D structure. The resulting foam (designated as LPU-rGO-ODA) was shown to retain the interconnected porous structure, with a water contact angle of 152°. Spectroscopic and microscopic analyses were conducted to investigate the structure and morphology of the foam. Sorption experiments with crude oil, engine oil, kerosene and chloroform showed that the LPU-rGO-ODA foam was an excellent oil sorbent with a sorption capacity of 26–68 times its own weight, which was much greater than that of a commercial non-woven polypropylene sorbent. The LPU-rGO-ODA foam also exhibited a high selectivity to oil sorption and excellent reusability over repeated sorption-squeezing cycles. The absorbed oils in the sorbent could be removed and collected simply by squeezing the oil-laden sponge, and the foam sorbent became ready for reuse in next sorption cycle. As such, LPU-rGO-ODA foam is expected to be a promising oil sorbent for potential applications in oil-spill clean-ups.

Amperometric sandwich immunoassay for the carcinoembryonic antigen using a glassy carbon electrode modified with iridium nanoparticles, polydopamine and reduced graphene oxide

The authors describe a sandwich-type electrochemical immunoassay for sensitive determination of the carcinoembryonic antigen (CEA). It is based on the use of iridium nanoparticles (Ir NPs) acting as electrochemical signal amplifier on the surface of a glassy carbon electrode. At first, polydopamine-reduced graphene oxide (PDA-rGO) was employed to immobilize primary antibody (Ab1) against CEA. Secondly, Ir-NPs were used as a support for the immobilization of secondary antibody (Ab2) to afford signal labels. The large surface area of PDA-rGO and the excellent electro-oxidative H2O2-sensing properties of Ir NPs result in a sensitive assay for CEA. Operated best at a working voltage of −0.6 V (vs. SCE), the assay has a linear range that extends from 0.5 pg⋅mL−1 to 5 ng·mL−1, and the lower detection limit is 0.23 pg⋅mL−1. The immunosensor displays satisfactory reproducibility and stability, thus demonstrating a reliable immunoassay strategy for tumor biomarkers. It was applied to the determination of CEA in spiked serum samples.

Electrochemical determination of hydrazine based on polydopamine-reduced graphene oxide nanocomposite

ABSTRACTIn this work, a simple and mild procedure was employed to synthesize polydopamine-reduced graphene oxide (PDA-RGO) nanocomposites, where the sheets of graphene oxide were functionalized firstly with PDA through self-polymerization. FTIR was used to confirm that the GO sheets had been functionalized successfully with PDA and reduced. Besides, UV-Vis and X-ray diffraction spectroscopy were employed to further demonstrate the formation of RGO. The electrochemical property of the PDA-RGO has been studied by the determination of hydrazine. The results indicated that the electrochemical oxidation of hydrazine was significantly improved by the obtained PDA-RGO nanocomposite due to the increased available surface area of electrode. A quick amperometric response was observed with the electrochemical sensor based on PDA-RGO nanocomposite for the hydrazine measurement in a wide linear range of 0.03–100 μM, where the limit of the detection was 0.01 μM.

Indocyanine Green-Loaded Polydopamine-Reduced Graphene Oxide Nanocomposites with Amplifying Photoacoustic and Photothermal Effects for Cancer Theranostics.

Photoacoustic (PA) imaging and photothermal therapy (PTT) as light-induced theranostic platforms have been attracted much attention in recent years. However, the development of highly efficient and integrated phototheranostic nanoagents for amplifying PA imaging and PTT treatments poses great challenges. Here, we report a novel phototheranostic nanoagent using indocyanine green-loaded polydopamine-reduced graphene oxide nanocomposites (ICG-PDA-rGO) with amplifying PA and PTT effects for cancer theranostics. The results demonstrate that the PDA layer coating on the surface of rGO could effectively absorb a large number of ICG molecules, quench ICG's fluorescence, and enhance the PDA-rGO's optical absorption at 780 nm. The obtained ICG-PDA-rGO exhibits stronger PTT effect and higher PA contrast than that of pure GO and PDA-rGO. After PA imaging-guided PTT treatments, the tumors in 4T1 breast subcutaneous and orthotopic mice models are suppressed completely and no treatment-induced toxicity being observed. It illustrates that the ICG-PDA-rGO nanocomposites constitute a new class of theranostic nanomedicine for amplifying PA imaging and PTT treatments.

Multifunctional Electrochemical Platforms Based on the Michael Addition/Schiff Base Reaction of Polydopamine Modified Reduced Graphene Oxide: Construction and Application.

In this paper, a new strategy for the construction of multifunctional electrochemical detection platforms based on the Michael addition/Schiff base reaction of polydopamine modified reduced graphene oxide was first proposed. Inspired by the mussel adhesion proteins, 3,4-dihydroxyphenylalanine (DA) was selected as a reducing agent to simultaneously reduce graphene oxide and self-polymerize to obtain the polydopamine-reduced graphene oxide (PDA-rGO). The PDA-rGO was then functionalized with thiols and amines by the reaction of thiol/amino groups with quinine groups of PDA-rGO via the Michael addition/Schiff base reaction. Several typical compounds containing thiol and/or amino groups such as 1-[(4-amino)phenylethynyl] ferrocene (Fc-NH2), cysteine (cys), and glucose oxidase (GOx) were selected as the model molecules to anchor on the surface of PDA-rGO using the strategy for construction of multifunctional electrochemical platforms. The experiments revealed that the composite grafted with ferrocene derivative shows excellent catalysis activity toward many electroactive molecules and could be used for individual or simultaneous detection of dopamine hydrochloride (DA) and uric acid (UA), or hydroquinone (HQ) and catechol (CC), while, after grafting of cysteine on PDA-rGO, simultaneous discrimination detection of Pb(2+) and Cd(2+) was realized on the composite modified electrode. In addition, direct electron transfer of GOx can be observed when GOx-PDA-rGO was immobilized on glassy carbon electrode (GCE). When glucose was added into the system, the modified electrode showed excellent electric current response toward glucose. These results inferred that the proposed multifunctional electrochemical platforms could be simply, conveniently, and effectively regulated through changing the anchored recognition or reaction groups. This study would provide a versatile method to design more detection or biosensing platforms through a chemical reaction strategy in the future.

Facile synthesis of uniform Pt nanoparticles on polydopamine-reduced graphene oxide and their electrochemical sensing

In this report, a facile and general approach was developed to prepare uniform Pt nanoparticles (NPs) on reduced graphene oxide (RGO) nanosheets, previously coated with a layer of polydopamine (PDA). The novel composites were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), and electrochemical technique, which had high electrochemically active surface area of 63.3m2g−1 and high electrocatalytic activity toward the reduction of O2. Furthermore, the Pt/PDA/RGO modified electrode exhibited a low detection limit of 0.4μM (S/N=3) and a high sensitivity of 13.3μAμM−1cm−2 for the detection of H2O2 as a model analyte.

Facile preparation of polydopamine-reduced graphene oxide nanocomposite and its electrochemical application in simultaneous determination of hydroquinone and catechol

A polydopamine (PDA)-reduced graphene oxide (RGO) nanocomposite was prepared by a one-step procedure and was characterized by Fourier transform infrared spectra (FTIR), electrochemical impedance spectra (EIS), and atomic force microscopy (AFM). The characterizations confirm the successful reduction of graphene oxide to RGO in the PDA-RGO nanocomposite. The application of PDA-RGO nanocomposite in simultaneous determination of hydroquinone (HQ) and catechol (CC) was investigated. The ΔEp between HQ and CC was 103 mV, which was wide enough to discriminate the dihydroxybenzene isomers. The peak current of HQ was linear to its concentration in the range of 1.0 × 10−6 to 2.3 × 10−4 M and the peak current of CC was linear to its concentration in the range of 1.0 × 10−6 to 2.5 × 10−4 M.

Solar simulator

A series of composite phase change materials (cPCMs) are fabricated through the one-pot method with the epoxidized methoxy polyethylene glycol (EmPEG) as the thermal energy unit and polydopamine-reduced graphene oxide (PDA-rGO) nanosheets as the interfacial enhancement. Structure and thermal properties such as phase change enthalpy, thermal repeatability, and light-to-thermal conversion capacity of EmPEG/PDA-rGO cPCMs with PDA-rGO content varying from 0.5 to 4 wt% have been detailed discussed. A superior stabilization performance of EmPEG/PDA-rGO cPCMs to pristine EmPEG is demonstrated based on the interfacial action from the incorporated PDA-rGO nanosheets. EmPEG/PDA-rGO-3 presents good structure-stabilized behavior after 100 heating-cooling cycles, and no liquid leakage appears up to 105 °C. In the meantime, EmPEG/PDA-rGO-3 illustrates a stable thermal reliability and thermal charging/discharging rate, and the light-to-thermal conversion efficiency reaches 96% under the 100 mW/cm2 irradiation. Thus, the structure-stabilized EmPEG/PDA-rGO cPCMs tuned by the interfacial interaction demonstrates the promising application in the field of the thermal energy storage and solar energy conversion.