Glen G. Briand

Bio: Glen G. Briand is an academic researcher from Dalhousie University. The author has contributed to research in topics: Bismuth & Coordination complex. The author has an hindex of 10, co-authored 13 publications receiving 855 citations.

Antimicrobial activities of synthetic bismuth compounds against Clostridium difficile.

Abstract: Clostridium difficile is a major nosocomial pathogen responsible for pseudomembranous colitis and many cases of antibiotic-associated diarrhea. Because of potential relapse of disease with current antimicrobial therapy protocols, there is a need for additional and/or alternative antimicrobial agents for the treatment of disease caused by C. difficile. We have synthesized a systematic series of 14 structurally simple bismuth compounds and assessed their biological activities against C. difficile and four other gastrointestinal species, including Helicobacter pylori. Here, we report on the activities of six compounds that exhibit antibacterial activities against C. difficile, and some of the compounds have MICs of less than 1 microgram/ml. Also tested, for comparison, were the activities of bismuth subcitrate and ranitidine bismuth citrate obtained from commercial sources. C. difficile and H. pylori were more sensitive both to the synthetic bismuth compounds and to the commercial products than were Escherichia coli, Pseudomonas aeruginosa, and Proteus mirabilis, and the last three species were markedly resistant to the commercial bismuth salts. Testing with human foreskin fibroblast cells revealed that some of the synthetic compounds were more cytotoxic than others. Killing curves for C. difficile treated with the more active compounds revealed rapid death, and electron microscopy showed that the bismuth of these compounds was rapidly incorporated by C. difficile. Energy dispersive spectroscopy X-ray microanalysis of C. difficile cells containing electron-dense material confirmed the presence of internalized bismuth. Internalized bismuth was not observed in C. difficile treated with synthetic bismuth compounds that lacked antimicrobial activity, which suggests that the uptake of the metal is required for killing activity. The nature of the carrier would seem to determine whether bismuth is transported into susceptible bacteria like C. difficile.

Coordination complexes of bismuth(III) involving organic ligands with pnictogen or chalcogen donors

Abstract: Publisher Summary The chapter presents an overview of the structural diversity demonstrated by complexes of bismuth(III) with organic-based ligands involving the elements of Groups 15 (pnictogens) and 16 (chalcogens) as donor sites, recognizing the potential for tailoring structure and reactivity by manipulation of the organic moiety. Although most complexes of bismuth obey standard valence guidelines, the high and variable coordination numbers accessible to bismuth are responsible for interesting and unpredictable structural arrangements. The formulas of well-defined bismuth compounds are presented to outline the type and extent of characterization data available for each, enabling assessment of the significance and relevance of the observations regarding synthesis and reactivity. Some of the structural features are described in detail to illustrate the novelty or generality of a particular arrangement. A diverse coordination chemistry is emerging for bismuth(III) made possible by a spacious and flexible coordination environment, allowing for coordination numbers in excess of 9.

Defining and Controlling the Aminoethanethiolate Chemistry of Bismuth(III): Synthesis and Comprehensive Characterization of the Homologous Thiolatobismuth Series

Abstract: Synthetic, spectroscopic (IR, Raman, NMR, APCI-MS), and X-ray crystallographic studies demonstrate that the highly favorable thiolation of bismuth can be controlled by manipulating stoichiometric c...

The structurally flexible bicyclic bis(2-hydroxyethanethiolato)bismuth(iii) complex: a model for asymmetric monoanionic chelation of bismuth(iii)

Abstract: Reaction of Bi(NO3)3 with 2-mercaptoethanol gives [Bi(SCH2CH2OH)2][NO3], 5(NO3), independent of stoichiometry. Other salts or derivatives of 5, 5(Cl) and 5(Br), are readily prepared by anion exchange reactions and can also be obtained by reaction of BiX3 (X = Cl, Br) with 2-mercaptoethanol. Reaction of Bi(CH3COO)3 with 2-mercaptoethanol gives the conjugate base of 5 which is readily protonated with glacial acetic acid to give the acetate salt 5(CH3COO). The compounds have been characterized by IR, Raman, and NMR spectroscopies and APCI mass spectrometry. X-ray crystallographic studies of 5(NO3) [crystal data: C4H10O5BiS2N·H2O, I41/a, a = 20.337(6) A, b = 20.337(6) A, c = 11.303(7) A, Z = 16], 5(Cl) [crystal data: C4H10O2BiS2Cl, P21/n, a = 8.653(2) A, b = 10.618(3) A, c = 10.564(2) A, β = 100.51(2)°, Z = 4], and 5(CH3COO) [crystal data: C6H13O4BiS2, P21/c, a = 8.089(2) A, b = 16.313(3) A, c = 8.708(2) A, β = 98.37(3)°, Z = 4] show them to each contain the bicyclic bis(2-hydroxyethanethiolato)bismuth fra...

Targeted Drug Delivery via the Transferrin Receptor-Mediated Endocytosis Pathway

Abstract: The membrane transferrin receptor-mediated endocytosis or internalization of the complex of transferrin bound iron and the transferrin receptor is the major route of cellular iron uptake. This efficient cellular uptake pathway has been exploited for the site-specific delivery not only of anticancer drugs and proteins, but also of therapeutic genes into proliferating malignant cells that overexpress the transferrin receptors. This is achieved either chemically by conjugation of transferrin with therapeutic drugs, proteins, or genetically by infusion of therapeutic peptides or proteins into the structure of transferrin. The resulting conjugates significantly improve the cytotoxicity and selectivity of the drugs. The coupling of DNA to transferrin via a polycation or liposome serves as a potential alternative to viral vector for gene therapy. Moreover, the OX26 monoclonal antibody against the rat transferrin receptor offers great promise in the delivery of therapeutic agents across the blood-brain barrier to the brain.

Engineering BiOX (X = Cl, Br, I) nanostructures for highly efficient photocatalytic applications

Abstract: Heterogeneous photocatalysis that employs photo-excited semiconductor materials to reduce water and oxidize toxic pollutants upon solar light irradiation holds great prospects for renewable energy substitutes and environmental protection. To utilize solar light effectively, the quest for highly active photocatalysts working under visible light has always been the research focus. Layered BiOX (X = Cl, Br, I) are a kind of newly exploited efficient photocatalysts, and their light response can be tuned from UV to visible light range. The properties of semiconductors are dependent on their morphologies and compositions as well as structures, and this also offers the guidelines for design of highly-efficient photocatalysts. In this review, recent advances and emerging strategies in tailoring BiOX (X = Cl, Br, I) nanostructures to boost their photocatalytic properties are surveyed.

An X-ray computed tomography imaging agent based on long-circulating bismuth sulphide nanoparticles

Abstract: Nanomaterials have become increasingly important in the development of new molecular probes for in vivo imaging, both experimentally and clinically. Nanoparticulate imaging probes have included semiconductor quantum dots, magnetic and magnetofluorescent nanoparticles, gold nanoparticles and nanoshells, among others. However, the use of nanomaterials for one of the most common imaging techniques, computed tomography (CT), has remained unexplored. Current CT contrast agents are based on small iodinated molecules. They are effective in absorbing X-rays, but non-specific distribution and rapid pharmacokinetics have rather limited their microvascular and targeting performance. Here we propose the use of a polymer-coated Bi(2)S(3) nanoparticle preparation as an injectable CT imaging agent. This preparation demonstrates excellent stability at high concentrations (0.25 M Bi(3+)), high X-ray absorption (fivefold better than iodine), very long circulation times (>2 h) in vivo and an efficacy/safety profile comparable to or better than iodinated imaging agents. We show the utility of these polymer-coated Bi(2)S(3) nanoparticles for enhanced in vivo imaging of the vasculature, the liver and lymph nodes in mice. These nanoparticles and their bioconjugates are expected to become an important adjunct to in vivo imaging of molecular targets and pathological conditions.

Two-dimensional graphene analogues for biomedical applications.

Abstract: The increasing demand of clinical biomedicine and fast development of nanobiotechnology has substantially promoted the generation of a variety of organic/inorganic nanosystems for biomedical applications. Biocompatible two-dimensional (2D) graphene analogues (e.g., nanosheets of transition metal dichalcogenides, transition metal oxides, g-C3N4, Bi2Se3, BN, etc.), which are referred to as 2D-GAs, have emerged as a new unique family of nanomaterials that show unprecedented advantages and superior performances in biomedicine due to their unique compositional, structural and physicochemical features. In this review, we summarize the state-of-the-art progress of this dynamically developed material family with a particular focus on biomedical applications. After the introduction, the second section of the article summarizes a range of synthetic methods for new types of 2D-GAs as well as their surface functionalization. The subsequent section provides a snapshot on the use of these biocompatible 2D-GAs for a broad spectrum of biomedical applications, including therapeutic (photothermal/photodynamic therapy, chemotherapy and synergistic therapy), diagnostic (fluorescent/magnetic resonance/computed tomography/photoacoustic imaging) and theranostic (concurrent diagnostic imaging and therapy) applications, especially on oncology. In addition, we briefly present the biosensing applications of these 2D-GAs for the detection of biomacromolecules and their in vitro/in vivo biosafety evaluations. The last section summarizes some critical unresolved issues, possible challenges/obstacles and also proposes future perspectives related to the rational design and construction of 2D-GAs for biomedical engineering, which are believed to promote their clinical translations for benefiting the personalized medicine and human health.