Structure–Function Relationships in Membrane-Based Hydrocarbon Separations Using N‑Aryl-Linked Spirocyclic Polymers

The separation of crude oil into its many components by distillation is an energy-intensive process. Membrane-based separations that avoid the use of heat can significantly reduce these energy requirements but are not yet able to obtain sufficiently high levels of molecular discrimination. While we have recently demonstrated initial success in the ability of membranes to fractionate crude oil, a better understanding of the relationship of polymer structure to membrane function will be necessary to design the library of membranes necessary to reduce the energy intensity of separation systems. In this work, we explored structural changes to a polymer, SBAD-1, that has shown exemplary membrane performance. The results suggest that, while aromatic interactions between solute and polymer impart favorable separation properties, polymer backbone rigidity has a much greater effect on membrane performance in organic solvent reverse osmosis separations, and an intermediate degree of rigidity is likely to be optimal

Resin-Supported Catalysts for CuAAC Click Reactions in Aqueous or Organic Solvents

The copper-catalyzed azide–alkyne cycloaddition click reaction is a valuable process for the synthesis of libraries of drug candidates, derivatized polymers and materials, and a wide variety of other functional molecules. In some circumstances, the removal of the copper catalyst is both necessary and inconvenient. We describe here two immobilized forms of a Cu-binding ligand that has been shown to accelerate triazole formation under many different conditions, using different resin supports that are appropriate for aqueous or organic solvents. Copper leaching from these resins was modest, allowing them to be reused in many reaction/filtration cycles without recharging with metal ion. The utility of this catalyst form was demonstrated in the convenient synthesis of 20 <i>N</i>-acetylgalactosamine derivatives for biological testing

Oral Delivery of Nanoparticles Carrying Ancestral Uricase Enzyme Protects against Hyperuricemia in Knockout Mice

The therapeutic value of delivering recombinant uricase to human patients has been appreciated for decades. The development of therapeutic uricases has been hampered by the fact that humans do not encode an endogenous uricase and therefore most recombinant forms of the protein are recognized as foreign by the immune system and are therefore highly immunogenic. In order to both shield and stabilize the active enzyme, we encapsulated a functional ancestral uricase in recombinant, noninfectious Qβ capsid nanoparticles and characterized its catalytic activity. Oral delivery of the nanoparticles moderated key symptoms of kidney dysfunction in uricase-knockout mice by lowering uric acid levels. Histological kidney samples of the treated mice suggest that delivery of recombinant uricase had a protective effect against the destructive effects of uric acid that lead to renal failure caused by hyperuricemia

Albumin-Oxanorbornadiene Conjugates Formed <i>ex Vivo</i> for the Extended Circulation of Hydrophilic Cargo

Oxanorbornadiene dicarboxylate (OND) reagents were explored for the purpose of binding and releasing chemical cargos from endogenous circulating serum albumins. ONDs bearing gadolinium chelates as model cargos exhibited variable conjugation efficiencies with albumin in rat subjects that are consistent with the observed reactivity of each linker and their observed stability toward serum hydrolases <i>in vitro</i>. The terminal elimination rate from circulation was dependent on the identity of the OND used, and increased circulation time of gadolinium cargo was achieved for linkers bearing electrophilic fragments designed to react with cysteine-34 of circulating serum albumin. This binding of and release from endogenous albumin highlights the potential of OND linkers in the context of optimizing the pharmacokinetic parameters of drugs or diagnostic agents

Modular Degradable Hydrogels Based on Thiol-Reactive Oxanorbornadiene Linkers

Oxanorbornadiene dicarboxylate (OND) reagents are potent Michael acceptors, the adducts of which undergo fragmentation by retro-Diels–Alder reaction at rates that vary with the substitution pattern on the OND moiety. Rapid conjugate addition between thiol-terminated tetravalent PEG and multivalent ONDs yielded self-supporting hydrogels within 1 min at physiological temperature and pH. Erosion of representative hydrogel formulations occurred with predictable and pH-independent rates on the order of minutes to weeks. These materials could be made non-degradable by epoxidation of the OND linkers without slowing gelation. Hydrogels prepared with OND linkers of equal valence had comparable physical properties, as determined by equilibrium swelling behavior, indicating similar internal network structure. Diffusion and release of entrained cargo varied with both the rate of degradation of PEG-OND hydrogels and the hydrodynamic radius of the entrained species. These results highlight the utility of OND linkers in the preparation of degradable network materials with potential applications in sustained release

Antitumor Humoral and T Cell Responses by Mucin‑1 Conjugates of Bacteriophage Qβ in Wild-type Mice

Mucin-1 (MUC1) is one of the top ranked tumor associated antigens. In order to generate effective anti-MUC1 immune responses as potential anticancer vaccines, MUC1 peptides and glycopeptides have been covalently conjugated to bacteriophage Qβ. Immunization of mice with these constructs led to highly potent antibody responses with IgG titers over one million, which are among the highest anti-MUC1 IgG titers reported to date. Furthermore, the high IgG antibody levels persisted for more than six months. The constructs also elicited MUC1 specific cytotoxic T cells, which can selectively kill MUC1 positive tumor cells. The unique abilities of Qβ-MUC1 conjugates to powerfully induce both antibody and cytotoxic T cell immunity targeting tumor cells bode well for future translation of the constructs as anticancer vaccines

Synthesis of Biologically Active <i>N</i>- and <i>O</i>‑Linked Glycans with Multisialylated Poly‑<i>N</i>‑acetyllactosamine Extensions Using <i>P. damsela</i> α2‑6 Sialyltransferase

Sialosides on <i>N</i>- and <i>O</i>-linked glycoproteins play a fundamental role in many biological processes, and synthetic glycan probes have proven to be valuable tools for elucidating these functions. Though sialic acids are typically found α2-3- or α2-6-linked to a terminal nonreducing end galactose, poly-LacNAc extended core-3 <i>O</i>-linked glycans isolated from rat salivary glands and human colonic mucins have been reported to contain multiple internal Neu5Acα2-6Gal epitopes. Here, we have developed an efficient approach for the synthesis of a library of <i>N</i>- and <i>O</i>-linked glycans with multisialylated poly-LacNAc extensions, including naturally occurring multisialylated core-3 <i>O</i>-linked glycans. We have found that a recombinant α2-6 sialyltransferase from <i>Photobacterium damsela</i> (Pd2,6ST) exhibits unique regioselectivity and is able to sialylate internal galactose residues in poly-LacNAc extended glycans which was confirmed by MS/MS analysis. Using a glycan microarray displaying this library, we found that Neu5Acα2-6Gal specific influenza virus hemagglutinins, siglecs, and plant lectins are largely unaffected by adjacent internal sialylation, and in several cases the internal sialic acids are recognized as ligands. Polyclonal IgY antibodies specific for internal sialoside epitopes were elicited in inoculated chickens

Glycomimetic Ligands for the Human Asialoglycoprotein Receptor

The asialoglycoprotein receptor (ASGPR) is a high-capacity galactose-binding receptor expressed on hepatocytes that binds its native substrates with low affinity. More potent ligands are of interest for hepatic delivery of therapeutic agents. We report several classes of galactosyl analogues with varied substitution at the anomeric, C2-, C5-, and C6-positions. Significant increases in binding affinity were noted for several trifluoromethylacetamide derivatives without covalent attachment to the protein. A variety of new ligands were obtained with affinity for ASGPR as good as or better than that of the parent <i>N</i>-acetylgalactosamine, showing that modification on either side of the key C3,C4-diol moiety is well tolerated, consistent with previous models of a shallow binding pocket. The galactosyl pyranose motif therefore offers many opportunities for the attachment of other functional units or payloads while retaining low-micromolar or better affinity for the ASGPR