<p>Lectin-functionalized, Poly [oligo(ethylene glycol) methyl ether methacrylate] (<em>POEGMA</em>) loaded with 3(R)-[(2(S)-pyrrolidinylcarbonyl)amino]-2-oxo-1-pyrrolidineacetamide (PAOPA) and poly(ethylene glycol)–block-poly(D,L-lactic-co-glycolic acid) (PEG-PLGA) nanoparticles loaded with haloperidol were prepared with narrow size distributions and sizes < 135 nm. The microgels and nanoparticles exhibited high <em>Solanum tuberosum </em>lectin (STL) conjugation efficiencies, encapsulation efficiencies, and drug loading capacities. The <em>in vitro</em> release of PAOPA and haloperidol was slow in physiological conditions over 96 hours, demonstrating minimal drug leakage and the potential for efficient drug transport to the targeted brain tissue. POAPA, POEGMA and the STL-functionalized POEGMA microgels were found to be non-toxic in both cell lines, indicating that they would not be toxic when administered intranasally or when they reach the brain. The nasal epithelial cell uptake of rhodamine-labelled microgels was higher in cells when the STL-functionalization was present. All haloperidol-loaded nanoparticle formulations were found to be highly effective at inducing catalepsy, while intranasal administration of STL-functionalized nanoparticles using the intranasal spray device increased the brain tissue haloperidol concentrations by 2-3.5 fold compared to STL-functionalized particles administered intranasally with a pipette. For the first time, brain tissue concentrations of rhodamine-labelled microgels confirmed that microgels are capable of passing the blood-brain barrier and that this uptake is size dependent. These formulations demonstrate promise in the reduction of the drug dose necessary to produce a therapeutic effect with antipsychotic drugs for the treatment of schizophrenia using a non-invasive route of administration.</p> / Master of Science (MSc)

Thrombin is the key protease that regulates hemostasis; the delicate balance between procoagulation and anticoagulation of blood. In clotting disorders, like deep vein thrombosis or pulmonary embolism, procoagulation is up-regulated, but propagation of clotting can be inhibited with drugs targeting the proteases involved, like thrombin. Such drugs however, have serious side effects (e.g., excessive bleeding) and some require monitoring during the course of treatment. The reason for these side effects is the mechanism by which the drugs’ act. The two major mechanisms are direct orthosteric and indirect allosteric inhibition, which will completely abolish the protease’s activity. Herein we sought an alternative mechanism called allosteric, partial inhibition, that has shown promise to truly regulate coagulation. Partial inhibition through allosteric mechanisms are well described for membrane-bound and oligomeric proteins. However proteases, specifically monomeric proteases (i.e., thrombin), have not shown this phenomenon until now. A small library of coumarin-based sulfated allosteric modulators (CSAMs) was synthesized to target a surface region called exosite 2; mainly composed of highly positively charged residues surrounded by hydrophobic patches. Studies revealed a non-competitive mechanism of binding with a range of IC50s between 0.2-58 µM combined with inhibitory efficacies (ΔY) between 22-73%; indicative of allosteric, partial inhibition. The KD was determined for the most potent compound (3g; IC50 = 0.2 µM, ΔY = 47%) at 0.15 µM. 3g was observed to bind at exosite 2 through unfractionated heparin competition and thrombin mutant studies. Additional computational studies were in agreement with the mutant and competition studies, showing the sulfate of 3g binding within a pocket containing R126 and R233. Fluorescence quenching and antithrombin inactivation rate studies described a conformational change to thrombin’s active site in the presence of 3g, supporting reduction of thrombin’s catalytic efficiency, without complete inhibition of thrombin’s proteolytic activities. Coupled enzyme assays and gel electrophoresis showed that in the presence of 3g, hydrolysis of fibrinogen (IC50 = 0.51 µM, ΔY = 94%) and protein C activation (IC50 = 1.7 µM, ΔY = 91%) is fully inhibited. Alternatively, FXIII activation was shown to be only partially inhibited by the presence of 3g, and FXI activation did not show any significant activation or inhibition. 3g was also shown to be active in human plasma and whole blood, but requiring much higher concentrations to induce an anticoagulant effect. Mice studies looking at the effects of 3g in vivo showed that even at high concentrations, showed no abnormal bleeding or any other irregularities. This work highlights a novel occurrence regarding thrombin’s allosteric functionality against multiple endogenous substrates. This library of compounds may be useful in the future development of allosteric inhibitors and probes that pose little to no risk of bleeding events by inducing partial inhibition.