Silk reservoir implants for sustained drug delivery

Area of Science:

• Biomaterials Science
• Drug Delivery Systems
• Regenerative Medicine

Background:

• Biomaterial implants for sustained drug delivery offer an alternative to daily oral medications.
• Current systems often require secondary surgeries for removal and may use harsh solvents in fabrication.
• There is a need for bioresorbable, easily fabricated drug delivery systems.

Purpose of the Study:

• To develop a biodegradable drug reservoir system using regenerated silk fibroin.
• To investigate the drug release kinetics and mechanical properties of the fabricated systems.
• To explore the potential for additive manufacturing of these silk-based devices.

Main Methods:

• Fabrication of tubular silk fibroin systems (< 250µm wall thickness) using an all-aqueous solution-gel-solid phase transition.
• In vitro release studies of two clinically relevant therapeutics over 30 days.
• Mechanical testing including radial compression and cyclic compression.
• Analysis of protein secondary structure (beta sheet content).

Main Results:

• Sustained release of therapeutics (> 100µg/day) for 30 days.
• Silk fibroin devices exhibited mechanical properties similar to cancellous bone (100-250 MPa Young's modulus).
• Devices showed good recovery under cyclic compression and could be fabricated into complex shapes.

Conclusions:

• A novel, all-aqueous fabrication process for biodegradable silk fibroin drug delivery systems was successfully developed.
• These silk-based devices demonstrate sustained therapeutic release and favorable mechanical properties, suitable for implantation.
• The additive molding capability opens possibilities for broader applications in tissue engineering and diagnostics.