Browsing School, Graduate by Subject "Nanomedicine"
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From Nanoparticles to Zinc Finger Proteins to Electronic Nicotine Delivery Systems: The Clinical and Biomolecular Evaluation of Potentially Toxic Heavy MetalsPhysicochemical Properties of Sodium Ferric Gluconate There are concerns that differences in iron release between brand sodium ferric gluconate (SFG) (Ferrlecit) and generic SFG (generic SFG) intravenous (IV) iron nanoparticle drugs, which are used to treat chronic kidney disease can be caused by differences in the products’ physicochemical properties. However, a standardized, SFG product specific, physicochemical measurement regulatory guidance is not available. Iron core measurements including optical spectroscopy, ICP-MS, XRPD, 57Fe Mössbauer spectroscopy, and XAS, found both products’ cores to be similar ferric-iron-oxide structures. Measurements focused on the carbohydrate shell including forced acid degradation, concentration dependent DLS, AUC, and GPC found differences in particle size, acid stability/iron lability, and molecular weight distribution, that may impact iron release. Cadmium Targeting of Tristetraprolin Zinc finger (ZF) proteins regulate inflammation and are a potential target for cadmium. Zinc bound double Cys3His domain ZF protein tristetraprolin (TTP) regulates inflammation by binding to AU-rich cytokine mRNA. Using a TTP peptide (TTP-2D), Zn2-TTP-2D, cadmium was observed to displace Zn in a concentration dependent manner by spin-filter/ICP-MS coupled to native ESI-MS. Cadmium was also found to displace zinc from RNA bound Zn2-TTP-2D complex (Zn2-TTP-2D/RNA) by ESI in a concentration dependent manner, resulting in Cd1Zn1-TTP-2D/RNA and Cd2-TTP-2D/RNA complexes. Using fluorescence anisotropy cadmium displacement of zinc from Zn2-TTP-2D/RNA complex did not disrupt RNA binding. E-Cig E-liquid Matrix’s Effect on Metal Aerosolization Potentially toxic levels of metals, such as chromium, nickel, copper, and lead, have been reported in e-liquids (liquids composed primarily of a mixture of propylene glycol (PG), glycerol (G)) and nicotine, and generated aerosols of electronic nicotine delivery systems (ENDS). However, the variables that affect metal transfer from the e-liquid to the aerosols are unknown. Using a custom ENDS aerosolization device and aerosolization approach, following CORESTA 81 guidance, the aerosolization of metal spiked model e-liquids (PG and G) were measured. Using ICP-MS to measure aerosol metal content to determine the effect of e-liquid on chromium, nickel, copper, and lead, it was found that all four metals are more readily aerosolized in PG dominant e-liquids than G dominant e-liquids.
Mechanisms of Dendrimer-Mediated Oral Drug DeliveryOral administration of chemotherapeutics remains a challenge despite the benefits for both the patient and health care system. To overcome the poor solubility and low oral bioavailability of anti-cancer drugs, polymeric delivery systems have been investigated. Dendrimers, a class of highly branched polymers, have proven useful for drug delivery because of their compact, nanoscopic size. Specifically, poly(amidoamine) (PAMAM) dendrimers have been shown to permeate the intestinal epithelium indicating potential as oral drug delivery carriers. While studies in our laboratory have determined the effects of surface modification on dendrimer transport and uptake, a large gap in knowledge exists in the transport and cytotoxicity mechanisms of PAMAM dendrimers. Additionally, alternatives to PAMAM dendrimers such as biodegradable poly-L-lysine (PLL) dendrimers have yet to be investigated for use in oral delivery. In this work we report the mechanisms of tight junction modulation by PAMAM dendrimers. While anionic dendrimers modulated tight junction proteins, cationic dendrimers opened tight junctions through phospholipase C-mediated calcium signaling allowing for paracellular small molecule transport. In comparison, cationic PLL dendrimers also allowed for small molecule transport with similar decreases in transepithelial electrical resistance. Small generation PAMAM and PLL dendrimers (16 and 32 surface amines) activated Caspase-3 and -7 resulting in apoptosis. In contrast, PLL dendrimers showed less long term toxicity compared to PAMAM dendrimers illustrating the benefits of dendrimer biodegradability. We also investigated the mechanisms of PLL dendrimer internalization and subcellular trafficking and the impact conjugation had on these mechanisms. The pH and enzymes present vary within different intracellular vesicles. Knowledge of the environment a drug delivery system will encounter is crucial for proper drug release. While PLL dendrimers were internalized via cholesterol- and dynamin-mediated endocytosis and macropinocytosis, conjugation site impacted uptake and localization. By conjugating a model compound to either the dendrimer core or surface, the uptake and transport properties of the delivery system were modified. Core-conjugated dendrimers had higher uptake and localized to the lysosomes and nucleus while surface conjugation resulted in higher transport and less accumulation in lysosomes. This research provides important knowledge for designing an effective dendrimer-based oral drug delivery system.