A biologically active, high-strength tissue adhesive is needed for numerous medical applications in tissue engineering and regenerative medicine. Integration of biomaterials or implants with surrounding native tissue is crucial for both immediate functionality and long-term performance of the tissue. Here, we use the biopolymer chondroitin sulphate (CS), one of the major components of cartilage extracellular matrix, to develop a novel bioadhesive that is readily applied and acts quickly. CS was chemically functionalized with methacrylate and aldehyde groups on the polysaccharide backbone to chemically bridge biomaterials and tissue proteins via a twofold covalent link. Three-dimensional hydrogels (with and without cells) bonded to articular cartilage defects. In in vitro and in vivo functional studies this approach led to mechanical stability of the hydrogel and tissue repair in cartilage defects.

No abstract

To utilize carbon nanotubes (CNTs) in various commercial and scientific applications, the graphene sheets that comprise CNT surfaces are often modified to tailor properties, such as dispersion. In this article, we provide a critical review of the techniques used to explore the chemical and structural characteristics of CNTs modified by covalent surface modification strategies that involve the direct incorporation of specific elements and inorganic or organic functional groups into the graphene sidewalls. Using examples from the literature, we discuss not only the popular techniques such as TEM, XPS, IR, and Raman spectroscopy but also more specialized techniques such as chemical derivatization, Boehm titrations, EELS, NEXAFS, TPD, and TGA. The chemical or structural information provided by each technique discussed, as well as their strengths and limitations. Particular emphasis is placed on XPS and the application of chemical derivatization in conjunction with XPS to quantify functional groups on CNT surfaces in situations where spectral deconvolution of XPS lineshapes is ambiguous.

The effect of 500 eV electrons on nanometer scale thick films of trimethyl(methylcyclopentadienyl)platinum(IV) (MeCpPtIVMe3), were studied in situ, under ultrahigh vacuum conditions using a combination of temperature-programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS), mass spectrometry, and reflection absorption infrared spectroscopy. TPD results revealed the presence of a monolayer state, with a desorption energy >10 kJ mol−1 larger than the multilayer. XPS data indicate that electron beam induced decomposition of adsorbed MeCpPtIVMe3 produced a carbonaceous film that contained Pt atoms in an electronic state intermediate between metallic Pt and Pt(IV). In addition to Pt(IV) reduction, electron beam irradiation was also accompanied by the evolution of methane and hydrogen from the adsorbate layer and the loss of C−H groups. The rate of Pt(IV) reduction and methane production and the loss of C−H groups from the film were all proportional to the MeCpPtIVMe3 coverage and the incident electron flux. Rate constants for all three processes were comparable, yielding an average reaction cross section of 2.2 × 10−16 cm2 for 500 eV electrons. Changes in the chemical composition of the adsorbate layer as a result of electron beam irradiation were consistent with a process in which one carbon atom desorbs for each MeCpPtIVMe3 molecule that decomposes. A comparison of the gas-phase products observed during the electron irradiation of adsorbed MeCpPtIVMe3 and CpPtIVMe3 support the idea that electron-stimulated decomposition of these platinum precursors involves by Pt−CH3 bond cleavage.