In this paper, a green one-step strategy is developed to fabricate three-dimensional (3D) graphene-based multifunctional material with the aid of tannic acid. Tannic acid (TA), a typical plant polyphenol widely present in woods, reduced GO and induced the self-assembly of reduced graphene oxide into graphene hydrogel. The preparation process was carried out in aqueous media under atmosphere pressure without using any toxic reducing agent or special instrument, which is a facile, green, and low-cost method. The as-prepared monolithic 3D graphene exhibits high porosity, low density, hydrophobicity, good mechanical performance, and thermal stability. In addition, it shows excellent adsorption toward dyes, oils, and organic solvent, which should be a promising candidate for efficient adsorbents in water purification. Moreover, the tannic acid retained in the skeleton of 3D graphene functions as a biofunctional component, which endows the TA-GH with good antibacterial capability.

Extracellular vesicles (EVs) are emerging as one of the many new and promising biomarkers for liquid biopsy of cancer due to their loading capability of some specific proteins and nucleic acids that are closely associated with cancer states. As such, the isolation and detection of cancer-derived EVs offer important information in noninvasive diagnosis of early-stage cancer and real-time monitoring of cancer development. In light of the importance of EVs, over the last decade, researchers have made remarkable innovations to advance the development of EV isolation and detection methods by taking advantage of microfluidics, biomolecule probes, nanomaterials, surface plasmon, optics, and so on. This review introduces the basic properties of EVs and common cancer-derived EV ingredients, and provides a comprehensive overview of EV isolation and detection strategies, with emphasis on liquid biopsies of EVs for cancer diagnostics.

Molecular imprinting at nanomaterial surfaces has shown good prospects to extract templates easily and to achieve excellent performances such as large binding capacity and fast adsorption. In this work, we describe a onestep approach to synthesize a novel surface protein-imprinted nanomaterial employing graphene as the supporting substrate and dopamine as the polymerizing monomer. By simply immersing graphene oxide (GO) in a weak alkaline solution of dopamine (DA) containing bovine hemoglobin (BHb), GO nanosheet was readily converted to reduced GO (RGO) by dopamine with simultaneous capping by a thin polydopamine film imprinted with BHb leading to the BHb imprinted PDA@RGO nanomaterials. Fourier transform infrared (FT-IR), ultraviolet−visible (UV−vis), Raman spectra, X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption experiments have been used to characterize the resulting imprinted PDA@RGO. The whole reaction process was conducted in aqueous solution at ambient temperature, which is easy to scale up at a low cost without pollution. In addition, because of the unique properties of graphene (large surface area, high surface-to-volume ratio) and polydopamine (high biocompatibility and controllable thickness), the prepared imprinted PDA@RGO not only possessed high binding capacity (198 mg/g) but also exhibited a fast adsorption kinetics (adsorb 89% of the maximum amount within 5 min) and good selectivity toward template protein (the imprinting factor α is 4.95). The outstanding recognizing behavior coupled to the low production cost and facile, quick, green preparation procedure makes the imprinted PDA@RGO attractive in specific protein recognition and separation, biosensors, and biochips.

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