On Demand Electrospun Bandages for Orthopedic Wound Protection

The practice of orthopedics is focused on preventing, diagnosing, and treating diseases and injuries of the musculoskeletal system. This entails using surgery to operate on the bones, muscles, tendons, and ligaments. Orthopedic surgery can manage genetic disorders, age-related musculoskeletal issues, and nervous system complications associated with the spinal column. Orthopedic wounds tend to be large for surgeon access to some locations and are required for implantation of large bones. In addition, lack of blood flow to medical implants and low blood flow in bone make these structures particularly susceptible to infection when exposed during surgery. These issues result in a high incidence of infection in orthopedic surgeries.

In our work, we utilized a patented portable electrospinning (ES) system to fabricate reliable slow-release antibiotic bandages that were tested on Staphylococcus aureus lawns over ten days. In addition, efficacy of the bandages was evaluated by quantifying infection % in 3D tissue culture following S. aureus infection and bandage application. The patented ES device use has been termed the electrostatic air-driven (EStAD, patent no. US12031236B2) electrospinner and enables electrospun materials to be deposited by a mobile or hand-held device directly onto any surface regardless of charge. In the system, a spinneret is placed within a cylindrical tube in front of an air flow source. External and insulated from the spinneret is a ring electrode surrounding the tube and on the opposite end of the air flow source. As the electric voltage is initiated in the ring electrode, polymer from the spinneret tip is stretched toward the ring electrode. Airflow is then used to force the polymer jet away from the ring and through the center onto any surface at the end of the barrel. This system provides a completely encased electric field that can be transported on emergency medical vehicles, in surgical rooms, and used in manufacturing without a shock risk or deposition surface limitations.

In this work, we used the EStAD to directly deposit antibiotic-laced bandages onto S. aureus lawns grown on agar. The ES parameters used included an applied 11.7 kV voltage, a polymer flow rate of 0.1 mL/hr, an air flow rate of 3.3 m/s, a separation distance from spinneret to petri dish of 2.5 cm, and a spinneret of 22 gauge. The polymer used was a 3:1 PCL to PEG blend with and without 4.5 mg/mL vancomycin. Following observation over 10-days, the antibiotic-laced bandage prevented S. aureus growth while the control did not prevent growth. In a second demonstration, the same electrospun bandages were fabricated and applied to 3D tissue cultures. For this, we grew epithelial organoids (kidney, lung, keratinocytes) in 3D Corning® Matrigel® Matrix and infected them with S. aureus. Following growth, the organoids were removed from the matrix by dispase and disrupted via TrypLE before internally contained bacteria (infection) was quantified for organoids treated with control or antibiotic-containing bandages. Bacterial quantification was carried out by serial dilution methods and plating to determine colony forming units (CFUs). Results from 3D tissue culture studies are being compiled for presentation at the MRS Spring Meeting. We hope to develop methodologies and formulations that will enable orthopedic surgeons to deposit these bandages on open orthopedic wounds for both physical and antibiotic protection during the most critical days following surgery.