What Are The Optimal Processing Conditions And Co-polymer Ratios For Electrospinning A Biodegradable Poly(lactic-co-glycolic Acid) (PLGA) Nanofiber Scaffold That Can Be Used To Deliver A Sustained Release Of A Growth Factor, Such As Vascular Endothelial Growth Factor (VEGF), To Enhance Angiogenesis In Tissue-engineered Vascular Grafts?

by ADMIN 338 views

To determine the optimal conditions for electrospinning PLGA nanofibers for VEGF delivery, consider the following organized approach:

PLGA Co-Polymer Ratios and Properties:

  1. Co-Polymer Ratios: Use ratios like 50:50, 75:25, or 85:15 PLGA. These balances provide moderate degradation rates suitable for sustained VEGF release.
  2. Molecular Weight: Opt for a molecular weight range of 50,000 to 100,000 Da to ensure appropriate degradation and mechanical properties.

Solvent and Solution Preparation:

  1. Solvent Selection: Use a mixture of dichloromethane (DCM) and dimethylformamide (DMF) for better fiber formation and solvent properties.
  2. Polymer Concentration: Maintain a concentration of 10-20% w/v to facilitate smooth fiber formation without bead defects.

Electrospinning Parameters:

  1. Voltage: Apply 10-25 kV to achieve optimal fiber diameters, avoiding extremes that cause fiber breaking.
  2. Flow Rate: Set a flow rate of 1-5 mL/h for a stable jet and consistent fiber formation.
  3. Collector Distance: Use a 10-20 cm distance to allow fiber stretching and proper deposition.
  4. Collector Type: Consider a rotating drum for fiber alignment, enhancing mechanical properties and cell orientation.

Environmental Conditions:

  1. Temperature and Humidity: Control these to prevent moisture absorption and degradation during electrospinning.

Surface Modification and VEGF Incorporation:

  1. Surface Treatment: Use oxygen plasma or coat with collagen/gelatin to improve cell adhesion.
  2. VEGF Incorporation: Blend VEGF into the polymer solution or use a coaxial setup for core-shell fibers to protect the protein.

Stabilization and Testing:

  1. Crosslinking: Apply genipin for less toxic stabilization or physical methods if protein denaturation isn't a concern.
  2. In Vitro Testing: Evaluate mechanical properties, VEGF release profiles using ELISA, and bioactivity through cell proliferation and angiogenesis assays.
  3. In Vivo Testing: Conduct histological analysis post-implantation to assess graft integration and vascular formation.

Conclusion:

By systematically evaluating these factors and testing different conditions, you can optimize PLGA nanofiber scaffolds for effective VEGF delivery and enhanced angiogenesis in vascular grafts.