Morphology Transition of Tripeptides from Porous Spherical to Rod-like Nanostructures for Small-Molecule Adsorption

Peptides possess a remarkable propensity to adopt distinct morphologies, ranging from simple aggregates to complex structures such as fibrils and nanotubes. Morphology transformation in peptides is intricately linked to the physicochemical properties of peptides and external factors such as pH, temperature, and solvent conditions. Thus, it is more complex. Herein, we present four tripeptides, Boc-LVL-OMe (LVL), Boc-IVI-OMe (IVI), Boc-LVI-OMe (LVI), and Boc-IVL-OMe (IVL), which undergo direct morphological transformation (except for Boc-IVL-OMe) with time. The morphological transformation from nanospheres to rod-like structures was verified using electron microscopic studies (FESEM and FETEM). Dynamic light scattering (DLS) studies further supported the results and are in good agreement with the observed phenomena. CD and FTIR studies were conducted for conformational analysis, suggesting a mixture of unordered and β-sheet conformations. Except for IVL, all other tripeptides are mesoporous and adsorb N₂ gas. Another important application of our designed tripeptides is that they can encapsulate the low-molecular-weight biologically active drug molecule curcumin. The encapsulation property and its sustained release after being treated with salt were studied by using fluorescence spectroscopy and fluorescence microscopy. Therefore, understanding the dynamics of these interactions and their impact on peptide morphology is crucial for harnessing their functional diversity in applications, such as drug delivery, tissue engineering, and nanotechnology.