Targeted and modular architectural polymers employing bioorthogonal chemistry for quantitative therapeutic delivery

There remain several key challenges to existing therapeutic systems for cancer therapy, such as quantitatively determining the true, tissue-specific drug release profile in vivo, as well as reducing side-effects for an increased standard of care. Hence, it is crucial to engineer new materials that allow for a better understanding of the in vivo pharmacokinetic/pharmacodynamic behaviours of therapeutics. We have expanded on recent “click-to-release” bioorthogonal pro-drug activation of antibody-drug conjugates (ADCs) to develop a modular and controlled theranostic system for quantitatively assessing site-specific drug activation and deposition from a nanocarrier molecule, by employing defined chemistries. The exploitation of quantitative imaging using positron emission tomography (PET) together with pre-targeted bioorthogonal chemistries in our system provided an effective means to assess in real-time the exact amount of active drug administered at precise sites in the animal; our methodology introduces flexibility in both the targeting and therapeutic components that is specific to nanomedicines and offers unique advantages over other technologies. In this approach, the in vivo click reaction facilitates pro-drug activation as well as provides a quantitative means to investigate the dynamic behaviour of the therapeutic agent.

There remain several key challenges to existing therapeutic systems for cancer therapy, such as quantitatively determining the true, tissue-specific drug release profile in vivo, as well as reducing side-effects for an increased standard of care.     

Dichlorosilylene: Rate constant for reaction with carbon monoxide and nitrous oxide

The absolute rate constanss for the gas-phase reactions of 1,1-dichlorosilylene with carbon monoxide and nitrous oxide have been determined using the flash photolysts-kinetic absorpiton spectroscopy technique. The bimolecular rate constant values at 25° C are: $$\begin{gathered} k\left( {Cl_2 Si + CO} \right) = \left( {6.3 \pm 0.7} \right) \times 10^8 M^{ - 1} s^{ - 1} \hfill \\ k\left( {Cl_2 Si + N_2 O} \right) = \left( {5.7 \pm 0.3} \right) \times 10^8 M^{ - 1} s^{ - 1} \hfill \\ \end{gathered} $$      

Effects of ionizing radiation on linear aromatic polyesters

The influence of chemical structure on the response of aromatic polyesters to high-energy ionizing radiation was studied. Systematic variations of polymers related to poly(ethylene terephthalate) were subjected to γ radiation, and the competitive chain scission and crosslinking reactions were determined by measuring changes in intrinsic viscosity and molecular weights. It was found that an increase in the paraffinic glycol segment of polyterephthalates facilitated crosslinking, while the protective nature of aromatic groups was demonstrated by modifying the dibasic acid segments. The influence of substituents on the terephthalate moiety was mixed: electronegative groups led to chain scission (as evidenced by decreased viscosities), but electropositive substituents exerted a stabilizing effect on polymer viscosity. In almost all cases, number-average molecular weights were decreased by exposure to γ radiation, regardless of viscosity behavior. Crystalline melting temperatures of the polymers generally were decreased by the combined radiation effects of chain scission and crosslinking.     

The thermal decomposition of group iib metal halide complexes: Part II. N,N,N′,N′-tetramethylethylenediamine and 1,2-diphenylphosphinoethane complexes

The preparation and pyrolysis procedures for 1/1 complexes MX₂·L (where M = Group IIB metal, XCl, Br or I and LN,N,N′,N′-tetramethylethylene-diamine (TMED) or 1,2-diphenylphosphinoethane (DPE))is reported. The decomposition of the cadmium chloride and bromide TMED complexes afford intermediates of varying stability. From far infrared spectrophotometry we conclude that the chloride intermediate is a four coordinate polymeric complex. Differential scanning calorimetry has been used to determine selected latent heats of fusion.     

The effect of frequency on the plasma polymerization of ethane

The plasma polymerization of ethane has been studied in the frequency range of from 50 Hz to 13.56 MHz. The rate of polymer deposition is strongly dependent on frequency, with significantly higher rates being observed at frequencies below 6 MHz. The effects of frequency can be interpreted in terms of a mechanism that assumes that polymer is formed by the reaction of surface free radicals, created by the bombardment of the growing polymer by charged species, with gas phase free radicals, formed by collisions of energetic electrons with monomer molecules.     

Dianion metallation reactions of n,n-dimethylvanillylamine and n,n-dimethylisovanillylamine

The utility of dianion chemistry in the synthesis of polyfunctional aromatics is demonstrated by the direct lithiation of the vanillylamine 1 and by the metal-halogen exchange reaction of the bromo isovanillylamines 9 and 10.     

Oxidation of perfluoroaromatics

3,4,5,6-Tetrafluoro-2-nitroaniline (I), 2,3,5,6-tetrafluoro-4-nitroaniline (IV) and 2,5,6-trifluoro-4-nitro-1,3-phenylenediamine (VI) react with nitrous acid to give 3,4,5-trifluoro-6-nitro-1,2-diazo-oxide (III), 3,5,6-trifluoro-4-nitro-1,2-diazo-oxide and (V) 5-fluoro-6-nitro-bis-1,2:3,4-diazo-oxide (VII), respectively. Reduction of the diazo-oxide (III) with hypophosphorous acid gives 4,5,6-trifluoro-3-nitrophenol (VIII). Treatment of 2,3,4,6-tetrafluoroacetanilide with nitric acid affords trifluoro-p-benzoquinone (X), the reduction of which gives trifluorohydroquinone (XI). Proton and fluorine chemical shifts and coupling constants of the new compounds are reported.     

2-fluoro-3-nitroaniline and 2-fluoro-1,3-phenylenediamine

2-Fluoro-3-nitroaniline (I), erroneously reported in the literature, has been synthesized by partial reduction of 2-fluoro-1,3-dinitrobenzene (II). Total reduction of (II) gives 2-fluoro-1,3-phenylenediamine (V). The NMR parameters of 1-fluoro-2,4-dinitrobenzene (IV), 2-fluoro-5-nitroaniline (III) and compounds (I), (II) and (V) are reported.     

pH as a trigger of peptide beta-sheet self-assembly and reversible switching between nematic and isotropic phases

The hierarchical self-assembly of rationally designed synthetic peptides into beta-sheet tapes, ribbons, fibrils, and fibers opens up potentially useful routes to soft-solidlike materials such as hydrogels, organogels, or liquid crystals. Here, it is shown how incorporation of Glu (-CH(2)CH(2)COOH) or Orn (-CH(2)CH(2)CH(2)NH(2)) into the primary structure of an 11 amino acid peptide enables self-assembly to be rapidly (seconds) and reversibly controlled by simply changing pH. Solutions of monomeric peptide, typically at concentrations in excess of 0.003 v/v, can be switched within seconds to, for example, nematic gel states comprised of interconnected orientationally ordered arrays of fibrils or vice versa. This is to be compared with the lyophilized peptide dissolution route to nematic fluids and gels which is impracticably long, taking many hours or even days. An important design principle, that stabilization of fibrillar dispersions requires of the order of one unit of net positive or negative charge per peptide molecule, is first demonstrated and then used to design an 11 amino acid peptide P(11)-3 (CH(3)CO-Gln-Gln-Arg-Phe-Gln-Trp-Gln-Phe-Gln-Gln-Gln-NH(2)) whose self-assembly behavior is independent of pH (1 < pH < 10). pH control is then incorporated by appropriately positioning Glu or Orn side chains so that the peptide-peptide free energy of interaction in the tapelike substructure is strongly influenced by direct electrostatic forces between gamma-COO(-) in Glu(-) or delta-NH(3)(+) in Orn(+), respectively. This design principle is illustrated by the behavior of two peptides: P(11)-4 (CH(3)CO-Gln-Gln-Arg-Phe-Glu-Trp-Glu-Phe-Glu-Gln-Gln-NH(2)) which can be switched from its nematic to its isotropic fluid state by increasing pH and P(11)-5 (CH(3)CO-Gln-Gln-Orn-Phe-Orn-Trp-Orn-Phe-Gln-Gln-Gln-NH(2)) designed to exhibit the converse behavior. Acid-base titrations of fibrillar dispersions reveal deprotonation of the gamma-COOH of Glu or of the delta-NH(3)(+) of Orn(+) occurs over wide bands of up to 5 pH units, a feature of polyelectrolytes. The values of the energy parameters controlling self-assembly can therefore be smoothly and continuously varied by changing pH. This enables isotropic fluid-to-nematic transitions to be triggered by relatively small additions of acid or base, typically 1 part in 10(3) by volume of 1 M HCl or NaOH.     

Preparation and Characterization of Binder for Inorganic Composites Made from Amorphous Mineral Raw Material

The preparation and characterization of a composite binder made through a sol-gel route from an amorphous mineral raw material has been studied. The amorphous mineral raw material is alumino-silicate based but contains also alkaline earth and some transition metal oxides. A stable sol can be prepared by dissolving the raw materials in formic acid. The drying and heat treatment of the subsequent gel has been studied by thermogravimetry, nuclear magnetic resonance, infrared spectroscopy as well as X-ray diffraction studies. The different constituents of the raw material have shown to play a major role during the drying and heat treatment of the gels. The binding effect of the binder was evaluated to be good by studying paper-binder composites as well as wetting properties.