Preparation and characterization of a iRGD-modified recombinant spider silk particles for antitumor polypeptide drug delivery into cancer cells.

Spider silk is highly attractive material because of its superior mechanical properties and excellent biocompatibility, enabling it to self-assemble into a wide range of morphological structures for drug delivery system. However, most spider silk particles developed as drug carriers are based on complex repetitive domains of spider silk proteins and exhibit relatively large particle sizes (> 300 nm), which limits their biomedical applications. In this study, we engineered a novel recombinant spider silk protein (NC-iRGD) by integrating terminal domains derived from major ampullate silk and the tumor-penetrating peptide iRGD. The silk particles were generated by mixing with a high-concentration potassium phosphate buffer and exhibited an average particle size of approximately 170 nm, which is smaller than that of other reported spider silk particles. Under incubation of silk particles in the drug solution, a 90% loading efficiency for the peptide drug (ChMAP-28) were determined. The cytotoxicity result showed that NC-iRGD particles displayed excellent biocompatibility and high drug loading efficiency in the neutral pH and low ionic strength. The release of ChMAP-28 was shown to be dependent on the ionic strength and pH of the release buffer. Additionally, NC-iRGD demonstrated enhanced tumor penetration and greater cytotoxicity against cancer cells compared to NC particles due to its iRGD sequence. Overall, the high drug loading capacity, controlled-release capability, and improved tumor penetration of NC-iRGD particles make them a promising novel drug delivery system for targeting polypeptide therapeutics to tumor microenvironments.