Carbohydrates are central components of biological systems, with roles ranging from metabolism to immune signaling, and are utilized as antibiotics, anti-coagulants, and biomaterials. Carbohydrate polymers with ionic functionality, such as alginic acid and chitosan, are used in hydrogels, tissue engineering, drug delivery, and as nucleic acid vectors. The clinical translation of polysaccharide biomaterials is hindered by the poor chemical definition, poor batch-to-batch consistency, and demanding purification process of naturally-obtained material. Additionally, there are few synthetic methods yielding enantiopure, water-soluble carbohydrate polymers with high molecular weight. To address the need for translatable carbohydrate biomaterials, our group recently introduced bioinspired Poly-Amido-Saccharides (PASs) as enantiopure, water-soluble, and well- defined carbohydrate polymers. These previously reported PAS polymers, however, mimic polysaccharides with primarily metabolic roles due to the lack of charged functional groups important for biomaterial applications. In this thesis, I describe the synthetic methodology of a regioselectively amine-functionalized β-lactam carbohydrate monomer, the subsequent synthesis of enantiopure, water-soluble amine-functional PASs (AmPAS), an evaluation of AmPAS biocompatibility and mucoadhesivity for pharmaceutical formulations, and the use of AmPAS for biocompatible nanoparticulate delivery of nucleic acids. Protecting group choices and regioselective modification are key to the synthesis of the AmPAS monomer via [2+2] cycloaddition with electron-deficient isocyanates. The results of a combined experimental and theoretical study indicate that bulky protecting groups of the 6’-OH enforce a 5H4 glycal conformation and favorable overlap of ring σC-O* with the glycal allyloxocarbenium system that enhances negative hyperconjugation effects due to electron withdrawing protecting groups. These data inform AmPAS monomer synthesis, where bulky, electron-withdrawing groups are required for regioselective glycal functionalization and intermediate protecting group stability is necessary to obtain cationic, water-soluble AmPAS. These polymers exhibit minimal cytotoxicity and immunogenicity, and, through single molecule force spectroscopy and ex vivo methods, significant mucoadhesivity important for pharmaceutical application. AmPAS are obtained with tunable molecular weight distributions to allow for nanoscale size- and charge-matched supramolecular assemblies with single stranded RNA and DNA oligonucleotides. These nanoparticles are stable in high serum conditions, exhibit high cell uptake, and are shown to successfully deliver anti-miR-21 oligonucleotides to mediate miR-21 knockdown in vitro. These promising results motivate the future application of AmPAS in small molecule and antisense oligonucleotide delivery formulations. / 2022-01-28T00:00:00Z

Selectively permeable biological membranes composed of lipophilic barriers inspire the design of biomimetic carrier-mediated membranes for aqueous solute separation. This work imparts selective permeability to lipid-filled pores of silica thin film composite membranes using carrier molecules that reside in the lipophilic self-assemblies. The lipids confined inside the pores of silica are proven to be a more effective barrier than bilayers formed on the porous surface through vesicle fusion, which is critical for quantifying the function of an immobilized carrier. The ability of a lipophilic carrier embedded in the lipid bilayer to reversibly bind the target solute and transport it through the membrane is demonstrated. Through the functionalization of the silica surface with enzymes, enzymatic catalysis and biomimetic separations can be combined on this nanostructured composite platform. The successful development of biomimetic nanocomposite membrane can provide for efficient dilute aqueous solute upgrading or separations using engineered carrier/catalyst/support systems. While the carrier-mediated biomimetic membranes hold great potential, fully understanding of the transport processes in composite synthetic membranes is essential for improve the membrane performance. Electrochemical impedance spectroscopy (EIS) technique is demonstrated to be a useful tool for characterizing the thin film pore accessibility. Furthermore, the effect of lipid bilayer preparation methods on the silica thin film (in the form of pore enveloping, pore filling) on ion transport is explored, as a lipid bilayer with high electrically insulation is essential for detecting activity of proteins or biomimetic carriers in the bilayer. This study provides insights for making better barriers on mesoporous support for carrier-mediated membrane separation process. Porous silica nanoparticles (pSNPs) with pore sizes appropriate for biomolecule loading are potential for encapsulating dsRNA within the pores to achieve effective delivery of dsRNA to insects for RNA interference (RNAi). The mobility of dsRNA in the nanopores of the pSNPs is expected to have a functional effect on delivery of dsRNA to insects. The importance of pores to a mobile dsRNA network is demonstrated by the lack of measurable mobility for both lengths of RNA on nonporous materials. In addition, when the dsRNA could not penetrate the pores, dsRNA mobility is also not measurable at the surface of the particle. Thus, the pores seem to serve as a “sink” in providing a mobile network of dsRNA on the surface of the particle. This work successfully demonstrates the loading of RNA on functionalized pSNPs and identified factors that affects RNA loading and releasing, which provides basis for the delivery of RNA-loaded silica particles in vivo.