Tailor-made spider-eggcase-silk spheres for efficient lysosomal drug delivery

Area of Science:

• Biomaterials Science
• Drug Delivery Systems
• Biotechnology

Background:

• Spider silks possess remarkable mechanical properties and biomimetic potential, making them attractive for biopolymer applications.
• Optimizing electrostatic interactions is crucial for effective lysosomal drug delivery systems.
• Genetic engineering offers a route to tailor protein properties for specific biomedical functions.

Purpose of the Study:

• To engineer spider-eggcase-silk protein for enhanced electrostatic interaction in lysosomal drug delivery.
• To develop a rapid method for assembling silk spheres with improved mechanical properties.
• To evaluate the drug loading, release kinetics, biocompatibility, and cellular delivery of engineered silk spheres.

Main Methods:

• Genetic engineering of spider-eggcase-silk protein with 5× His Tag for a specific isoelectric point (4.8).
• Rapid assembly of silk spheres using a facile HFIP-on-oil method (10 s) followed by ethanol post-treatment.
• Atomic Force Microscopy (AFM) indentation to assess mechanical properties.
• Doxorubicin loading efficiency determination.
• In vitro drug release studies at different pH values (4.5 and 7.4).
• Cytotoxicity, platelet adhesion, and hemolysis assays for biocompatibility and hemocompatibility assessment.
• Cellular uptake and intracellular trafficking studies in Hela cells.

Main Results:

• Engineered silk spheres exhibited improved compressive modulus after ethanol post-treatment.
• Achieved a maximum of 35% and an average of 30% Doxorubicin loading efficiency.
• Demonstrated pH-responsive drug release, with release at pH 4.5 being 4.5-fold higher than at pH 7.4 after 96 h.
• Silk spheres showed intrinsic biocompatibility and good control of drug release in neutral conditions.
• Doxorubicin-loaded silk spheres exhibited good hemocompatibility.
• Efficient lysosomal delivery and subsequent nuclear release of Doxorubicin in Hela cells within 24 h.

Conclusions:

• Genetically engineered spider silk spheres are a promising platform for pH-responsive, targeted lysosomal drug delivery.
• The facile fabrication method and enhanced mechanical properties contribute to the potential of these silk spheres.
• The demonstrated biocompatibility and controlled drug release profile support their application in cancer therapy or other biomedical fields.