Abstract: The field of solid state nanopores presents nearly limitless customizability in both the types of molecules that can be studied as well as the aspects of their structures which can be examined. Following an introduction to solid-state nanopores, their operating principles, and their trajectory as a biosensing technology, this dissertation presents their use in the single-molecule resolution characterization of the structures of transfer ribonucleic acid (tRNA) and cytochrome c (cyt c) protein. It then examines conjugates of lipid nanoparticles (LNPs) with messenger RNA (mRNA) payloads. In the case of tRNA, it investigates the effects of both point mutation A14G and post-transcriptional methylation m1G on the translocation signals of human mitochondrial tRNALeu(UAA), and found that each combination of these modifications affects the molecule’s dwell time and blockade behavior. From this, the relative structural stabilities of each variant can be inferred. In the case of cyt c, this work demonstrates the identification of configuration changes during translocation and assembles a statistical model determining the number of unique states measured, the favorability of transitions among the states detected, and basic characteristics inferred from their respective translocation behaviors. Finally, it presents methods for measuring the size of mRNA-laden LNPs to determine the efficiency of mRNA filling processes for drug delivery applications, using unprocessed LNPs as controls. The methods employed and experimental results of each case, the biomedical relevance of the results, as well as their respective implications on biosensing technology, are discussed.