Luqman A. Adams

NEW SYNTHESES OF THE MARINE ALKALOIDS EUDISTOMINS D AND U

Abstract Short and convergent syntheses of eudistomins U and D are reported. The approach is based on a convergent methodology which involves such reactions as metalation and heteroring cross-coupling.

Carbolines, Part VIII. An Original Synthesis of the Antibiotic Eudistomin T

Abstract An original and short synthesis of Eudistomin T is reported. The approach is based on a convergent methodology which involves such reactions as metalation, heteroring cross-coupling and cyclization.

Bioactivity of quaternary glass prepared from bentonite clay

Alkoxysilane precursors are the most widely used silica source for sol–gel preparation of silicate-based bioactive glass. However, due to their high cost, alternative sources such as bentonite clay are desirable. In the present work, bentonite clay was reacted with sodium hydroxide (NaOH) to extract sodium metasilicate (Na2SiO3). The obtained Na2SiO3 was converted to gel which was then sintered at 950 ℃ for 3 h to give the bioactive glass in the quaternary composition SiO2–NaO–CaO–P2O5. The resulting glass was incubated in simulated body fluid (SBF) for 0–7 days to evaluate the bioactivity. Furthermore, glass samples were characterized before and after SBF study by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). Results obtained showed the presence of Na2Ca2Si3O9 (combeite) crystal as the major crystalline phase and the formation of hydroxyapatite (HA) and hydroxycarbonated apatite (HCA) on the surface of the glass after immersion in SBF. The material showed potentials for application as scaffold in bone tissue repair.

Evaluation of Baylis–Hillman Routes to 3-(Aminomethyl)coumarin Derivatives

Abstract The relative merits of two different Baylis–Hillman approaches toward the preparation of coumarin derivatives, containing peptide-like side chains, have been explored. In one approach, use of methyl acrylate as the activated alkene requires a protecting group strategy, an approach that is not necessary when using tert-butyl acrylate. [Supplementary materials are available for this article. Go to the publishers online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.] GRAPHICAL ABSTRACT

A new route to sol-gel crystalline wollastonite bioceramic

ABSTRACT Artificial bone graft materials formed from wollastonite have been extensively used in bone repair because of their high degree of bioactivity and biocompatibility, thereby justifying the development of a protocol for large-scale production. This work reports a novel route for preparing wollastonite via the sol-gel process using bentonite clay as a cheap silica source. The obtained wollastonite was characterized for morphology, elemental composition, phase composition and bioactivity using scanning electron microscopy, energy dispersive X-ray analysis, X-ray diffraction and Fourier transform infrared spectroscopy. Results obtained revealed that wollastonite phase was successfully formed in the material and it showed ability to induce formation of apatite within 0.5 day in biological fluid, an indicator for bone-bonding capability. Overall, the wollastonite prepared from the bentonite clay exhibited properties comparable to that synthesized from commercially obtained sodium metasilicate. Hence, our synthetic route may be useful for commercial-scale preparation of wollastonite.

Bioactivity and mechanical characterization of porous glass scaffold derived from sand

A such as Tetraethyl orthosilicate (TEOS) and trimethyl orthosilicate (TMOS) are expensive precursors to silicate-based sol-gel-derived bioactive glasses. Facile approaches involving low cost substitutes are desirable for bioactive glass implants in bone regeneration therapy. Quaternary system SiO2-Na2O-CaO-P2O5 bioactive glass was prepared by the sol-gel method from sand as precursor. The glass monolith was sintered at 950 oC, before carrying out immersion studies in simulated body fluid (SBF) for 28 days. The monolith was characterized by SEM-EDX, FTIR, XRD and compression testing. The surface morphology of the sintered monolith from SEM revealed prominent macropores with interconnected micropores and evidently dense pore struts. Porosity determined was about 82 %. After immersion the surface became heterogeneous showing agglomeration of hydroxyapatite. EDX analysis determined before and after immersion in SBF indicated an increase in Ca, P and C concentration with immersion time, attributed to the formation of carbonated hydroxyapatite (HCA). The Ca/P atomic ratio reached a value of 1.56 after immersion in SBF for 14 days tending towards 1.67 for non-stoichiometric hydroxyapatite. pH of the SBF gradually increased from 7.4 to 8.7 over the first 9 days. Result of the FTIR analysis gave bands at 872, 604 and 554 cm-1 diagnostic for HCA. Compression test indicated strength of 0.37 MPa which falls in range for cancellous bone. XRD analysis further confirmed presence of (HCA). The bioactive material obtained from locally sourced precursor in this study shows promising properties that can be explored as porous scaffold for bone repair. Luqman A. Adams, J Tissue Sci Eng 2013, 4:2 http://dx.doi.org/10.4172/2157-7552.S1.012