Graphene Oxide Based Theranostic Platform for <i>T</i>₁‑Weighted Magnetic Resonance Imaging and Drug Delivery

Magnetic resonance imaging (MRI) is a powerful and widely used clinical technique in cancer diagnosis. MRI contrast agents (CAs) are often used to improve the quality of MRI-based diagnosis. In this work, we developed a positive <i>T</i>₁ MRI CA based on graphene oxide (GO)–gadolinium (Gd) complexes. In our strategy, diethylenetriaminepentaacetic acid (DTPA) is chemically conjugated to GO, followed by Gd­(III) complexation, to form a <i>T</i>₁ MRI CA (GO–DTPA–Gd). We have demonstrated that the GO–DTPA–Gd system significantly improves MRI <i>T</i>₁ relaxivity and leads to a better cellular MRI contrast effect than Magnevist, a commercially used CA. Next, an anticancer drug, doxorubicin (DOX), was loaded on the surface of GO sheets via physisorption. Thus-prepared GO–DTPA–Gd/DOX shows significant cytotoxicity to the cancer cells (HepG2). This work provides a novel strategy to build a GO-based theranostic nanoplatform with <i>T</i>₁-weighted MRI, fluorescence imaging, and drug delivery functionalities

Enhanced Proliferation and Osteogenic Differentiation of Mesenchymal Stem Cells on Graphene Oxide-Incorporated Electrospun Poly(lactic-<i>co</i>-glycolic acid) Nanofibrous Mats

Currently, combining biomaterial scaffolds with living stem cells for tissue regeneration is a main approach for tissue engineering. Mesenchymal stem cells (MSCs) are promising candidates for musculoskeletal tissue repair through differentiating into specific tissues, such as bone, muscle, and cartilage. Thus, successfully directing the fate of MSCs through factors and inducers would improve regeneration efficiency. Here, we report the fabrication of graphene oxide (GO)-doped poly­(lactic-<i>co</i>-glycolic acid) (PLGA) nanofiber scaffolds via electrospinning technique for the enhancement of osteogenic differentiation of MSCs. GO-PLGA nanofibrous mats with three-dimensional porous structure and smooth surface can be readily produced via an electrospinning technique. GO plays two roles in the nanofibrous mats: first, it enhances the hydrophilic performance, and protein- and inducer-adsorption ability of the nanofibers. Second, the incorporated GO accelerates the human MSCs (hMSCs) adhesion and proliferation versus pure PLGA nanofiber and induces the osteogenic differentiation. The incorporating GO scaffold materials may find applications in tissue engineering and other fields

Silicon Phthalocyanine Covalently Functionalized N‑Doped Ultrasmall Reduced Graphene Oxide Decorated with Pt Nanoparticles for Hydrogen Evolution from Water

To improve the photocatalytic activity of graphene-based catalysts, silicon phthalocyanine (SiPc) covalently functionalized N-doped ultrasmall reduced graphene oxide (N-usRGO) has been synthesized through 1,3-dipolar cycloaddition of azomethine ylides. The obtained product (N-usRGO/SiPc) was characterized by transmission electron microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, Raman spectra, X-ray photoelectron spectroscopy, fluorescence, and UV–vis spectroscopy. The results demonstrate that SiPc has been successfully grafted on the surface of N-usRGO. The N-usRGO/SiPc nanocomposite exhibits high light-harvesting efficiency covering a range of wavelengths from the ultraviolet to visible light. The efficient fluorescence quenching and the enhanced photocurrent response confirm that the photoinduced electron transfers from the SiPc moiety to the N-usRGO sheet. Moreover, we chose Pt nanoparticles as cocatalyst to load on N-usRGO/SiPc sheets to obtain the optimal H₂ production effect. The platinized N-usRGO/SiPc (N-usRGO/SiPc/Pt) demonstrates good hydrogen evolution performance under both UV–vis and visible light (λ>400 nm) irradiation. The apparent quantum yields are 1.3% and 0.56% at 365 and 420 nm, respectively. These results reveal that N-usRGO/SiPc/Pt nanocomposite, consolidating the advantages of SiPc, N-usRGO, and Pt NPs, can be a potential candidate for hydrogen evolution from water under UV–vis or visible light irradiation

Surface Plasmon Resonance Enhanced Light Absorption and Photothermal Therapy in the Second Near-Infrared Window

Enhanced near-field at noble metal nanoparticle surfaces due to localized surface plasmon resonance (LSPR) has been researched in fields ranging from biomedical to photoelectrical applications. However, it is rarely explored on nonmetallic nanomaterials discovered in recent years, which can also support LSPR by doping-induced free charge carriers, let alone the investigation of an intricate system involving both. Here we construct a dual plasmonic hybrid nanosystem Au–Cu₉S₅ with well controlled interfaces to study the coupling effect of LSPR originating from the collective electron and hole oscillations. Cu₉S₅ LSPR is enhanced by 50% in the presence of Au, and the simulation results confirm the coupling effect and the enhanced local field as well as the optical power absorption on Cu₉S₅ surface. This enhanced optical absorption cross section, high photothermal transduction efficiency (37%), large light penetration depth at 1064 nm, excellent X-ray attenuation ability, and low cytotoxicity enable Au–Cu₉S₅ hybrids for robust photothermal therapy in the second near-infrared (NIR) window with low nanomaterial dose and laser flux, making them potential theranostic nanomaterials with X-ray CT imaging capability. This study will benefit future design and optimization of photoabsorbers and photothermal nanoheaters utilizing surface plasmon resonance enhancement phenomena for a broad range of applications