Temperature controlled cellular internalization of hybrid peptides

This study examined various hybrid peptides that possess both collagen [(POG)n] and cell penetrating peptides (CPP) [(RRG)n or Rn] sequences. The hybrid peptides were able to fold into triple helical conformation when the surrounding temperature was lower than their transition temperature (Tm) which resulted in cellular internalization. The peptide that lacked collagen [(POG)n] domain failed to penetrate the cell. The hybrid peptide under study, FL7V1, was shown to have the ideal Tm (17.3°C) for the potential purpose as a drug carrier. In vitro study of FL6V1 with temperature gradient showed cellular internalization at low temperatures (10°C-20°C) while no uptake was achieved at high temperatures (24°C-32°C). In vivo study of FL7V1 with P. leidyi corresponded with the results of in vitro study at constant and gradient temperature.