The application of Baylis-Hillman methodology has afforded access to a range of β-hydroxypropionate ester-AZT conjugates as potential dual-action HIV-1 IN/RT inhibitors. Two families comprising a total of nine β-hydroxypropionate ester-AZT conjugates were synthesised. The first family was accessed using O-benzylated salicylaldehydes and methyl acrylate and the second from unprotected salicylaldehydes using tert-butyl acrylate as the activated alkene. Spectroscopic methods were employed to fully characterize the compounds. Propargylation of the respective Baylis-Hillman adducts was achieved via conjugate addition of propargylamine. The resulting products were then employed in Cu(I)-catalysed “click” reactions with azidothymidine (AZT) to yield the desired β-hydroxypropionate ester-AZT conjugates. Exploratory studies were also conducted to access 4-hydroxycoumarins from Baylis-Hillman derived adducts and to construct customized chiral Baylis-Hillman reaction sites. Many 4- hydroxycoumarins are known to exhibit a wide range of biological activities, and extending Baylis-Hillman methodology to access these systems is an important challenge. Two approaches were investigated. The first involved the formation of a 4-phthalimidocoumarin, aromatisation and hydrolysis of which was expected to lead to the 4-hydroxycoumarin target. The second, a variation of the first, involved the use of 4-(chrolomethyl)coumarin intermediates. Unfortunately, while various intermediates were prepared and characterised, neither approach led ultimately to the desired targets. N-substituted borneol-10-sulfonamides were constructed from camphor-10- sulfonyl chloride as chiral Baylis-Hillman reaction sites. In a preliminary study, however, none of the N-substituted borneol-10-sulfonamides exhibited Baylis-Hillman catalytic activity.

No description available.

Yes / We report a simple temperature-responsive bioconjugate system comprising superfolder green fluorescent protein (sfGFP) decorated with poly[(oligo ethylene glycol) methyl ether methacrylate] (PEGMA) polymers. We used amber suppression to site-specifically incorporate the non-canonical azide-functional amino acid p-azidophenylalanine (pAzF) into sfGFP at different positions. The azide moiety on modified sfGFP was then coupled using copper-catalyzed “click” chemistry with the alkyne terminus of a PEGMA synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization. The protein in the resulting bioconjugate was found to remain functionally active (i.e., fluorescent) after conjugation. Turbidity measurements revealed that the point of attachment of the polymer onto the protein scaffold has an impact on the thermoresponsive behavior of the resultant bioconjugate. Furthermore, small-angle X-ray scattering analysis showed the wrapping of the polymer around the protein in a temperature-dependent fashion. Our work demonstrates that standard genetic manipulation combined with an expanded genetic code provides an easy way to construct functional hybrid biomaterials where the location of the conjugation site on the protein plays an important role in determining material properties. We anticipate that our approach could be generalized for the synthesis of complex functional materials with precisely defined domain orientation, connectivity, and composition. / Engineering and Physical Sciences Research Council (EPSRC), University of Warwick, National Science Foundation (U.S.) (NSF), United States. Defense Advanced Research Projects Agency (DARPA), Seventh Framework Programme (European Commission) (FP7), European Research Council (ERC)

No description available.

La squalénisation est une méthode de vectorisation sous forme nanoparticulaire qui consiste àcoupler de manière covalente un dérivé du squalène à des principes actifs hydrophiles tels que lesanalogues nucléosidiques. Les conjugués amphiphiles obtenus sont capables de s’auto-organiserspontanément dans l’eau en nanoparticules d’une centaine de nanomètres de diamètre etpossèdent des activités anticancéreuses ou antivirales remarquables. Notre objectif était d’étendrecette stratégie à différentes classes d’antitumoraux, comme les antimétabolites, les antimitotiqueset les agents alkylants. Différents dérivés du squalène ont ainsi été synthétisés puis couplés à cesprincipes actifs pour former les bioconjugués squalénisés correspondants. Il a été montré que cesprodrogues étaient capables de s’auto-assembler en nanoparticules spontanément en milieuaqueux, que le principe actif soit hydrophile ou hydrophobe. Les suspensions nanoparticulaires deces prodrogues se sont montrées actives in vitro sur différentes lignées cellulaires cancéreuseshumaines et murines et in vivo chez la Souris sur des modèles de cancer. La squalénisation a donc étéétendue à diverses familles de composés anticancéreux confirmant qu’il s’agit d’une méthodegénérale de vectorisation pourvue d’un fort potentiel thérapeutique. / Squalenoylation is a strategy of vectorization consisting in coupling squalene derivatives tohydrophylic drugs as nucleoside analogues. The amphiphilic conjugates obtained are able to selfassembleinto nanoparticles with a diameter of 100 nm in water. In addition those nanoparticleshave shown impressive anticancer and antiviral activities. Our objective was to extend this strategyto different anticancer drugs as antimetabolites, antimitotics and alkylating agents. Differentsqualenoyl derivatives have been synthesised and then coupled to drugs to furnish thecorresponding squalenoylated biconjugates. It has been shown that those prodrugs were able toself-assemble into nanoparticles in water. Nanoparticles of the bioconjugates are active in vitro ondifferent human cancer cell lines and in vivo in Mice on different cancer models. Squalenoylation hasfinally been extended to numerous anticancer drugs, proving that this strategy is a general methodof vectorization with a high therapeutic potential.

Thesis (Ph. D. in Chemistry)--Vanderbilt University, Dec. 2008. / Title from title screen. Includes bibliographical references.

This work reports on the conjugation of differently shaped Pt nanoparticles (PtNPs) with ClGa(III) 5,10,15,20-tetrakis-(4-carboxyphenyl) porphyrin (1) as well as chloro - (5,10,15,20-tetrakis (4- (4- carboxy phenycarbonoimidoyl) phenyl) porphyrinato) gallium(III) (2) The work also reports on platination of dihydroxosilicon octacarboxyphthalocyanine (OH)₂SiOCPc (3) to give dihydroxosilicontris(diaquaplatinum)octacarboxyphthalocyanine (OH)₂SiOCPc(Pt)₃ (4). The resulting conjugates were used for photodynamic antimicrobial chemotherapy against S. aureus, E. coli and C. albicans. The degree of photo-inactivation is dependent on concentration of the conjugates, light dose (fluence) and illumination time. The log reduction obtained for 1 when conjugated to cubic PtNPs was 4.64 log (which indicate 99.99 percent of the bacteria have been killed), which is much higher than 3.94 log unit for 1-hexagonal PtNPs and 3.31 log units for 1-unshaped PtNPs. Complex 2 conjugated to hexagonal PtNPs showed 18 nm red shift in the Soret band when compared to 2 alone. Complex 2 and 2-hexagonal PtNPs as well showed promising photodynamic antimicrobial chemotherapy (PACT) activity against S. aureus, E. coli and C. albicans in solution where the log reduction obtained was 4.92, 3.76, and 3.95 respectively for 2-hexagonal PtNPs. The singlet oxygen quantum yields obtained were higher at 0.56 for 2-hexagonl PtNPs in DMF while that of 2 was 0.52 in the same solvent. This resulted in improved PACT activity for 2-hexagonal PtNPs compared to 2. Complex 4 showed slight blue shifting of the absorption spectrum when compared to complex 3 The antimicrobial activity of 4 were promising as the highest log reduction value was observed when compared to the porphyrin conjugates.

The main objectives of the research presented in this thesis were to understand mechanistic aspects of the photochemistry of ferritin (Ftn) and bioconjugates that consisted of Ftn linked to gold nanoparticles (AuNPs). The photochemistry investigated in this thesis repurposed Ftn from its role in biological systems as an iron-sequestration protein to potential applications in photocatalysis and nanobiomedicine. The first phase of the thesis research developed a mechanistic understanding of the underlying mechanisms involved in the photochemistry of Ftn with relevance to photocatalysis. In particular, research was designed to determine whether the light-induced bandgap excitation of the semiconductor core of horse-spleen ferritin (HSFtn) resulted in electron transfer from the inorganic core to aqueous redox active reactant via electron transport through the 2 nm thick shell of HSFtn. To investigate this mechanistic pathway, 4-5 nm copper (hydr)oxide nanoparticles were mineralized within the internal volume of HSFtn (CuFtn). It was shown that, unlike the native iron oxyhydroxide-bearing (Ferrihydrite; Fh) Ftn, the visible light photoexcitation of the inorganic core of CuFtn (measured optical bandgap to be 3.65 eV) did not exhibit any release of redox-active metal cation from the HSFtn cage into solution. By photoexciting CuFtn in the presence of aqueous chromate (Cr(VI)) it was shown that the Cr(VI) underwent reduction to Cr(III) in solution. The research strategy eliminated the possibility that metal cations escaping from the HSFtn during photoexcitation could be responsible for Cr(VI) reduction. Hence, the research showed for the first time that electrons resulting from a photoexcited metal oxide core of Ftn could transfer through the protein shell to reduce an aqueous redox active reactant. The research also investigated the wavelength-dependent photochemistry of CuFtn to show that bandgap excitation was indeed responsible for the electrons that transfer across the protein shell. In a second project, the research investigated the bioconjugation of anisotropic AuNPs—gold nanorods (AuNRs) and gold nanostars (AuNSs)—to human H-type ferritin (HFtn). After attaching the AuNRs or AuNSs to HFtn, it was shown that the near-infrared (NIR) radiation excitation of the localized surface plasmon resonance (LSPR) of the AuNR or AuNS conjugated to HFtn led to the activation of the Fh core of the protein. This NIR photochemistry (λ = 850 nm light) resulted in the release of Fe(II) from the Ftn and also led to the reduction of Cr(VI) when it was present in the aqueous phase. The novel synthetic protocols to synthesize the bioconjugates focused on attaching the AuNRs and AuNSs to the solvent-exposed cysteines (Cys) on HFtn. The research also developed techniques for the removal of colloidal stabilizing surfactants, such as cetyltrimethyl ammonium bromide (CTAB), and TritonX-100 (TX-100), from anisotropic AuNPs (AuNR/AuNS) before their attachment to HFtn. The removal of the surfactant was not only important for attachment to the HFtn, but it also removed a cytotoxic species so that the bioconjugates could be used in research that had applications to biomedicine. Research also investigated synthetic strategies to form bioconjugates that consisted of spherical gold nanoparticles (AuNSps) attached to HSFtn. In contrast to HFtn, HSFtn contains a few solvent exposed Cys groups. Hence, a challenge that was overcome in this research was to populate the outer surface of HSFtn with thiol groups (-SH) so that AuNSps could be attached. To meet this challenge, the surface primary amine-containing amino acids (Lysine) in HSFtn were modified to active Cys using N-succinimidyl S-acetylthioacetate (SATA). After this chemical modification of HSFtn, it was shown that a relatively high density of AuNSps could be attached to HSFtn. This SATA-modified HSFtn bioconjugate system (AuNSp-HSFtn) exhibited the release of Fe(II) at wavelengths of light where λ > 475 nm. In the absence of AuNSp, HSFtn released Fe(II) during exposure to light at wavelengths of light where λ < 475 nm. The activation of the bandgap at longer wavelengths of light (λ > 475 nm) was due to the excitation of the 532 nm plasmon resonance of AuNSp and the presumed transfer of hot electrons to the inner Fh core of HSFtn. A final project investigated the use of the AuNR-HFtn bioconjugates as a photodynamic strategy utilizing NIR to suppress the growth of cancer cells with the expectation that this process will occur through the mechanism of ferroptosis. We carried out experiments that exposed prostate cancer cells (PC3) to AuNR-HFtn, and during NIR irradiation, they showed the ability to limit the growth of the cells compared to experiments where the cells were exposed to just HFtn or AuNRs. The results suggested that Fe(II) released from the HFtn led to cancer cell death through a process that might be ferroptosis. Future studies will need to investigate this possibility and whether the bioconjugates developed in this thesis will offer a novel therapeutic strategy for cancer/tumor suppression. / Chemistry

No description available.

Conjugates of soybean trypsin inhibitor (SBTI) and potato serine protease inhibitor (PSPI) immobilized on metal oxide particles of ~100nm diameter were prepared. Inhibition of trypsin hydrolysis of BAPA by these conjugates was measured and enzyme kinetics constants kcat, KM, kcat/KM and ki were determined. Metal oxide particles presented an inhibitory effect similar to that of a competitive inhibitor, noticed through the increase value of the K M constant. Furthermore, PSPI conjugates had the highest inhibition of trypsin, illustrated by the significantly higher value of KM relative to the value for particles only.