Hydroxyl-Terminated Saponified Natural Rubber Based on the H2O2/P25-TiO2 Powder/UVC-Irradiation System

Natural rubber (NR), a long-chain hydrocarbon polymer mostly consisting of cis-1,4-polyisoprene units, has a high molecular weight (MW) and viscosity, enabling it to show excellent physical properties. However, NR has no reactive functional group, making it difficult to react with other molecules, especially in manufacturing processes. The functionalized low-molecular-weight NR (FLNR) is a requirement to disperse ingredients into the rubber adequately. Here, the FLNR was prepared by a photochemical degradation process under UVC-irradiation in the presence of H2O2 using P25-titanium oxide (TiO2) powder as a photocatalyst. The optimum condition for the preparation of FLNR was the use of 2.0 g of TiO2 powder per 100 g of rubber and H2O2 at 20% w/w under UVC-irradiation for 5 h. The hydroxyl groups were found on the NR chains due to the chain-scission of polyisoprene chains and hydroxyl radicals in the system. The weight average MW of NR decreased from 12.6 × 105 to 0.6 × 105 gmol−1, while the number average MW decreased from 3.3 × 105 to 0.1 × 105 gmol−1.

Studies and synthetic methodology of Nampt inhibition

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] The purpose of this research is to study and synthesize an array of a highly potent pharmaceuticals that can selectively cause apoptosis in various cancer cells and to synthesize click chemistry components to be used in drug delivery systems. Utilizing hydrophobic properties of carboranes, an array of drug derivatives were synthesized as potential Nampt inhibitors. These drugs selectively bind to nicotinamide Phosphoribosyl transferase (Nampt), preventing cancer cells from replenishing nicotinamide adenine dinucleotide (NAD) through the salvage pathway which leads to apoptosis. The association constants of unsubstituted o-, m-, and p-carborane, adamantane, and their derivatives with [beta]-cyclodextrin ([beta]-CD) are reported for the first time using displacement binding in an aqueous solution. Although hydrophobicity plays a major role in the association with [beta]-CD, unsubstituted o-carborane which is the least hydrophobic carborane derivative, exhibits the highest Ka' of 2690 M[subscript -1]. The Ka' values for the m-, and p-carborane isomers decrease with decreasing dipole moment (1830 M-1 and 1560 M[subscript -1] respectively). Adamantane exhibits a Ka' value lower than each of the three carborane isomers at 1410 M[subscript -1]. These studies indicate that cyclodextrin inclusion complexes could be well suited as a drug delivery vehicle for our carborane containing drug derivatives. Click chemistry linkers functionalized with azide or alkyne functional groups were synthesized for use in a peptide drug conjugate. These linkers also utilized an amine reactive functional group to allow for reaction with amines found in peptides.

Direct subphthalocyanine conjugation to bombesin vs. indirect conjugation to its lipidic nanocarrier

Azido-liposomes give fluorophores/contrast agents with no reactive functional group available on their backbone a second chance to be (indirectly) bioconjugated (with bombesin).

Amine-decorated nanocrystalline cellulose surfaces: synthesis, characterization, and surface properties

In this present work, terminal amino-functionalized nanocrystalline cellulose derivatives were prepared using a simple two-step protecting group-free protocol under aqueous reaction conditions at room temperature. Carboxylate groups were first introduced onto the surface of nanocrystalline cellulose (NCC) via a TEMPO-mediated oxidation. Then, reaction of surface-carboxylated NCC with bifunctional amines of small alkyl chain length by EDC/NHS-mediated coupling furnished the desired aminated NCC via an amide linkage. Surface covalent functionalization was confirmed by Fourier transform infrared spectroscopy, elemental analysis, and X-ray photoelectron spectroscopy. Size, surface charge, morphology, and thermal properties were obtained by various techniques. STEM images revealed no change in structure and morphology of the materials after TEMPO-mediated oxidation but a slight agglomeration was observed after surface covalent functionalization with diamines. While amide linkage confers stability, terminal primary amine groups on the surface of NCC represent a versatile reactive functional group for bioconjugation with other biomolecules for potential biomedical applications.

Functionalization of porphyrins: towards the synthesis of bifunctional chelates for bismuth coordination

We report the condensation of 3-chloromethyl-benzoyl chloride with two atropisomers ααββ and αβαβ of meso-5,10,15,20-tetrakis-(2-amino)phenylporphyrin (TAPP), followed by the reaction of the anion of either cyano-acetic acid ethyl ester or (4-nitro-phenyl)-acetic acid ethyl ester to prepare various pre-organized strapped porphyrins. These two reagents were selected as both allow the easy formation of the anion in the α position of the ester group while their electron-withdrawing group (EWG) can be further transformed in a reactive functional group. In the ααββ series, this reaction leads to three isomeric porphyrins differing only by the location of their ethoxycarbonyl groups, oriented either towards the center of the porphyrin or maintained outside of the cavity. In the αβαβ series, as expected, a single porphyrin is obtained in which both straps bear an ethoxycarbonyl group, precursor of a hanging carboxylic function and a cyano or a 4-nitro-phenyl group, which can be reduced to an amine function, suitable for the coupling on a biomolecule.

Construction of Nonbiofouling Biofunctional Glass Surface by Self-Assembled Monolayer and Graft Hydrophilic Polymer

This paper introduces a new method of surface modification by self-assembled monolayer (SAM) and polymer monolayer grafting. Since most of the glass surfaces lack the reactive functional group, an activation process with 3-(trimethoxysilyl)propyl methacrylate(TPM) is used in our experiment to generate the vinyl reactive sites on the substrate surface for further graft polymerization. The TPM saline layer acts as the “anchor” part to link the functional part onto the surface of substrate. The paper summarizes the surface modifications by the polymerizations of PEGMA, AA(Acrylic acid) and NVP(Nitrogen-vinyl-2-pyrrolidone) respectively and their applications for protein adsorption and cell adhesion through a series of measurements. In previous research, AA and NVP had also been adopted for surface treatment and had achieved good results. The substrate can be glass, alumina, silicon, metals or stainless steel. We choose glass as our substrate during the experiment.

Biomedical Applications of Gold Nanoparticles Functionalized Using Hetero-Bifunctional Poly(ethylene glycol) Spacer

ABSTRACTTo increase the targeting potential, circulation time, and the flexibility of surface-attached biomedically-relevant ligands on gold nanoparticles, hetero-bifunctional poly(ethylene glycol) (PEG, MW 1, 500) was synthesized having a thiol group on one terminus and a reactive functional group on the other. Coumarin, a model fluorescent dye, was conjugated to the PEG spacer and gold nanoparticles were modified with coumarin-PEG-thiol. Surface attachment of coumarin through the PEG spacer decreases the fluorescence quenching effect of gold nanoparticles. The results of cellular cytotoxicity and fluorescence confocal analyses showed that the PEG spacer modified nanoparticles were essentially non-toxic and could be efficiently internalized in the cells within one hour of incubation.