Achieving Cross Time-Domain Multiplexed Signal Cascade and Cancer Exosomes Identification by Bridging Long Lifetime Phosphor to NIR-II Lanthanide Energy Transfer

Designing lanthanide luminescence lifetime sensors in the second near-infrared (NIR-II) window holds great potentials for physiological studies. However, the single lifetime signal is confined to one or two orders of magnitude of signal variation, which limits the sensitivity of lifetime probes. In this study, a lifetime cascade system, i.e., ZGO:Mn, Eu-DNA-1/TCPP-PEI70K@Yb-AptEpCAM, with a variety of signals (τm, τn, τµ, τm/τn and τm/τµ) is constructed for exosome identification using time-domain multiplexing. The sensitized ligand TCPP acts as both target-modulated switch and a bridge for connecting long lifetime ZGO:Mn, Eu-DNA-1 emitter to lanthanide Yb3+. This drives successive dual-path energy transfer and forms two D(donor)-A(acceptor) pairs. The lifetime variation is dominantly modulated by arranging TCPP as energy intermediate relay to covert milliseconds to nanoseconds to microseconds. It enables a broad lifetime range of six orders of magnitude. The presence of exosome specifically recognizes aptamers on TCPP-PEI70K@Yb-AptEpCAM to impede D-A pairs and reverse multiplexed response signals of the lifetime cascade system. The ratio lifetime signals τm/τn and τm/τµ achieve prominent exosome quantification and exosome type differentiation attributed to signal amplification. The cascade system relying on lifetime criteria can realize precise quantization and provide an effective strategy for subsequent physiological study.

One-step synthesis of nitrogen-functionalized graphene aerogel for efficient removal of hexavalent chromium in water

The efficient removal of hexavalent chromium (Cr(VI)) with high toxicity has attracted widespread concern since it causes serious harm to ecological environment and public health. Herein, we report a novel nitrogen-functionalized graphene aerogel with stereoscopic structure through a simple hydrothermal method and freeze drying for Cr(VI) removal from water. Graphene oxide (GO) and nitrogenous organics polyethyleneimine (PEI) and pyrrole are used as raw materials for preparing PEI/polypyrrole/GO aerogel (PPGA) adsorbent. PEI and pyrrole act as nitrogen sources to introduce nitrogenous functional groups, and also take on the role of cross-linkers for helping GO sheets to form stereoscopic structure. The obtained PPGA has a fast adsorption rate, excellent reusability, and shows a remarkable adsorption capacity for Cr(VI) up to 458.24 mg/g under the optimal conditions (pH 2.0, 298 K, Cr(VI): 600 mg/L, dosage: 0.4 g/L). The adsorption process of Cr(VI) on PPGA can fit the pseudo-second-order kinetic model well. Analysis of intraparticle diffusion shows that the Cr(VI) removal process is a multi-step process. Adsorption thermodynamic and isotherm results demonstrate Cr(VI) adsorption on PPGA is a spontaneous endothermic process. The adsorption mechanism involves electrostatic attraction, redox, and chelation. In general, this work provides a simple and eco-friendly way to prepare PPGA, which has a great potential for actual application of Cr(VI) removal in effluent.

One-Step Synthesis of 3D Pore-Structured Adsorbent by Cross-Linked PEI and Graphene Oxide Sheets and Its Application in CO2 Adsorption

In this study, a one-step method of polyethylenimine (PEI) cross-linking graphene oxide (GO) was used to prepare a 3D pore-structured adsorbent with abundant amine groups for chemisorption of CO₂. The cross-linking of PEI with GO sheets and the vacuum freeze-drying step are the keys to the formation of the 3D pore structure. The results of characterization analysis revealed that the as-prepared adsorbent had a 3D porous structure rich in amine groups. Besides, the adsorption/desorption test showed that the prepared adsorbent has excellent and stable adsorption performance, and the maximum CO₂ adsorption capacity is 2.18 mmol/g at 343 K and 10 vol % CO₂. Moreover, the adsorption kinetics analysis indicated that the adsorption process was dominated by homogeneous adsorption, and the adsorbent had a strong affinity with CO₂. Finally, the correlation analysis shows that the kinetic constants obtained by the Avrami model simulation can be effectively used for the actual CO₂ adsorption process design.

Graphene Oxide/Polyethylenimine Aerogels for the Removal of Hg(II) from Water

This article reports the synthesis of an aerogel involving reduced graphene oxide (rGO) and polyethylenimine (PEI), and describes its potential application as an effective sorbent to treat Hg(II) contaminated water. The rGO/PEI sorbent was synthetized using a supercritical CO₂ method. N₂ physisorption, electron microscopy, and elemental mapping were applied to visualize the meso/macroporous morphology formed by the supercritical drying. The advantages of the synthetized materials are highlighted with respect to the larger exposed GO surface for the PEI grafting of aerogels vs. cryogels, homogeneous distribution of the nitrogenated amino groups in the former and, finally, high Hg(II) sorption capacities. Sorption tests were performed starting from water solutions involving traces of Hg(II). Even though, the designed sorbent was able to eliminate almost all of the metal from the water phase, attaining in very short periods of time residual Hg(II) values as low as 3.5 µg L⁻¹, which is close to the legal limits of drinking water of 1–2 µg L⁻¹. rGO/PEI exhibited a remarkably high value for the maximum sorption capacity of Hg(II), in the order of 219 mg g⁻¹. All of these factors indicate that the designed rGO/PEI aerogel can be considered as a promising candidate to treat Hg(II) contaminated wastewater.

Performance Evaluation of New Chalcone Oxime Functionalized Graphene Oxide as a Corrosion Inhibitor for Carbon Steel in a Hydrochloric Acid Solution

This study aims to synthesize new chalcone oxime functionalized graphene oxide (CO-GO) and investigate the enhancement in corrosion protection. The morphology and structure of the synthesized CO-GO have been characterized by elemental analysis: Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), and scanning electron microscopy (SEM). Moreover, the effectiveness of corrosion inhibition was investigated by utilizing electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP). The results of the above analyses demonstrate that CO-GO has an outstanding corrosion inhibitor performance of up to 94% and acts as a mixed-type inhibitor with a primarily anodic action. The effect of temperature on a carbon steel surface indicates that the tested composites are chemisorbed. A few techniques were able to provide surface characterization such as scanning electron microscopy and ultraviolet (UV)-visible spectroscopy to confirm inhibitor adsorption on the carbon steel surface.

A stable and easily regenerable solid amine adsorbent derived from a polyethylenimine-impregnated dialdehyde-cellulose/graphene-oxide composite

A DAC-GO composite adsorbent with high CO2 adsorption capacity and low regeneration energy consumption was prepared through oxidation-gelation and crosslinking-amination.

Efficient antimony removal by self-assembled core-shell nanocomposite of Co3O4@rGO and the analysis of its adsorption mechanism

Co₃O₄@rGO were facilely prepared by template free self-assemble in this study. The morphology of Co₃O₄@rGO was actiniaria-like core-shell structural nanocomposites. The formation mechanism of Co₃O₄@rGO core-shell nanocomposite was discussed according to its significant time-dependent morphology evolution course. To evaluate the application potential of Co₃O₄@rGO, its adsorption performance toward highly toxic antimony ions were studied. The Co₃O₄@rGO nanocomposite exhibit high anti-interference ability and high adsorption ability. The maximum adsorption capacities towards Sb(III) and Sb(V) are 151.04 and 165.51 mg/g, respectively. River water samples containing antimony violating the limit were used to evaluate the practical application of Co₃O₄@rGO, and high performance was achieved. The EU and China limits for antimony in drinking water can be met by using mesoporous Co₃O₄@rGO treating the actual river water samples with original antimony concentration lower than 50 μg/L. Adsorption isotherm, adsorption kinetics, pH and co-existing ions effects were also studied in details. The results indicate that mesoporous Co₃O₄@rGO is an excellent adsorbent for antimony removal. Mesoporous Co₃O₄@rGO nanocomposite is a potential candidate for antimony removal from waste water.

3D Graphene-Based Macrostructures for Water Treatment

Recently, 3D graphene-based macrostructures (3D GBMs) have gained increased attention due to their immense application potential in water treatment. The unique structural features (e.g., large surface area and physically interconnected porous network) as well as fascinating properties (e.g., high electrical conductivity, excellent chemical/thermal stability, ultralightness, and high solar-to-thermal conversion efficiency) render 3D GBMs as promising materials for water purification through adsorption, capacitive deionization, and solar distillation. Moreover, 3D GBMs can serve as scaffolds to immobilize powder nanomaterials to build monolithic adsorbents and photo-/electrocatalysts, which significantly broadens their potential applications in water treatment. Here, recent advances in their synthesis and application toward water purification are highlighted. Remaining challenges and future perspectives are elaborated to highlight future research directions.

Enhanced electron transfer mediated detection of hydrogen peroxide using a silver nanoparticle–reduced graphene oxide–polyaniline fabricated electrochemical sensor

The current study aims at the development of an electrochemical sensor based on a silver nanoparticle–reduced graphene oxide–polyaniline (AgNPs–rGO–PANI) nanocomposite for the sensitive and selective detection of hydrogen peroxide (H₂O₂).

Pyridine-based functionalized graphene oxides as a new class of corrosion inhibitors for mild steel: an experimental and DFT approach

Two functionalized graphene oxides, diazo pyridine functionalized graphene oxide and diamino pyridine functionalized graphene oxide, were synthesised and evaluated as corrosion inhibitors on mild steel in 1 M hydrochloric acid.

A novel macroporous polymer–inorganic nanocomposite as a sorbent for pertechnetate ions

A novel magnetic macroporous poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) (mPGME) was prepared by suspension copolymerization and functionalized with diethylenetriamine (mPGME-deta).

Synthesis and characterization of rGO/ZrO2 nanocomposite for enhanced removal of fluoride from water: kinetics, isotherm, and thermodynamic modeling and its adsorption mechanism

A nanocomposite of rGO/ZrO₂ prepared by a simple hydrothermal method using GO and ZrOCl₂·8H₂O has been successfully utilized for the removal of fluoride from aqueous solutions by adsorption.