Self-assembled peptide nanoparticles for photodynamic therapy: morphological and mechanical effects on hepatocellular carcinoma cells

Self-assembling peptides, offering favorable biocompatibility, high stability, and easy incorporation of various functionalities, have demonstrated enormous potential for the precise design of next-generation nanodrugs for non-invasive tumor therapy. Peptide-based supramolecular photodynamic therapy (PDT) has shown great promise as an emerging modality for cancer treatment, achieving substantially-enhanced photosensitizer delivery selectivity and treatment efficacy, based on peptide biological activity and self-assembly potential. Although considerable research has been conducted toward fabricating self-assembling peptide-based smart nanodrugs for PDT, few studies have investigated cellular biophysical responses as indicators of tumor function and metabolic state. Here, via atomic force microscopy (AFM)-based morphological and mechanical measurements, including optical microscopy and scanning electron microscopy, we observed, for the first time, variation in membrane stiffness of human liver (HepG2) cancer cells treated with self-assembling peptides serving as a PDT nanodrug. This biophysical information will help to establish a comprehensive understanding of the anticancer effect of peptide-based smart nanodrugs, and highlight the exceptional ability of AFM in determining cell-surface properties.