Plastic nanoparticles (PNPs) ranging from nanometers to micrometers pose significant risks to biological membranes and proteins by disrupting peptide structure and function. While ensemble and theoretical studies suggest that PNPs can denature peptides, the nanoscale mechanisms remain poorly understood. To address this, single-molecule Förster Resonance Energy Transfer (smFRET) and circular dichroism (CD) spectroscopy were combined to investigate the conformational dynamics of small model peptides exposed to various PNPs. Using a custom Total Internal Reflection Fluorescence (TIRF) microscope, both α-helical and β-sheet peptides were studied—particularly focusing on α-helices due to their relevance in key proteins like hemoglobin, insulin, and α-synuclein. We observed that hydrophobic PNPs induce structural distortions, likely through interactions with nonpolar amino acids in the peptides. This thesis explores the kinetics and mechanisms of these peptide-PNP interactions, offering new insights into how PNP pollution can impair protein structure at the molecular level.