Spidroin-based nanoparticles derived from spider aggregate gland glue for efficient peptide drug delivery

Spiders can produce a wide variety of silk types for daily functions, each exhibiting unique mechanical properties and biological roles. Among all silk types, aggregate silk is distinctive in that it is a viscoelastic, amorphous, and wet adhesive material, rather than a solid fibrous structure. However, unlike other spider fibroins (spidroins), studies on the biomedical applications of aggregate spidroin (AgSp) remain scarce, particularly in the context of drug delivery systems. Here, we designed and produced three recombinant AgSp (rAgSp) proteins (rAgSp2R, rAgSp4R, and rAgSp6R) with different molecular weights, and fabricated them into nanoparticles (rAgSp-NPs) using the gallic acid (GA)-induced self-assembly method. The physical properties of these particles were characterizaed using scanning electron microscopy, fourier-transform infrared spectroscopy, and zeta potential measurements. As the molecular weight of recombinant proteins increases, the colloidal stability of rAgSp-NPs improves. The rAgSp-NPs exhibit high β-sheet content and show no cytotoxicity toward normal cells. Upon incubation of the silk particles with a positively charged ChMAP-28 solution, which possesses antitumor activity, can be effectively loaded onto all three types of rAgSp-NPs via electrostatic interactions. Significantly, drug-loaded rAgSp6R-NPs exhibited a higher efficiency in restraining tumor progression compared to free peptide drugs. Overall, these novel silk particles provide insights into the self-assembly of aggregate spidroins and represent a promising new drug delivery system for peptide therapeutics.