*2.1. Materials*

Anhydrous dichloromethane (DCM), triethylamine (TEA), poly (ethylene glycol) Mn = 530 g mol−<sup>1</sup> , sodium chloride (NaCl), hydroxyethyl methacrylate (HEMA), diphenyl (2,4,6-trimethylbenzoyl)phosphine oxide (TPO), 2-tert-butyl-6(5-chloro-2H-benzo-triazol-2 yl)-4-methylphenol (BLS-1326), methacryloyl chloride, Solutol-HS 15, phosphate-buffered saline (0.01 M PBS, pH 7.4), HPLC-grade acetonitrile, water, and chloroform were purchased from Sigma Aldrich (St. Louis, MO, USA). Poly(ε-caprolactone) (PCL) (3 mm OD) string was purchased from Lactel absorbable polymers (Birmingham, Al, USA), and was made from poly (ε-caprolactone) ester terminated (Mn = 68 kDa). Cotton strings (1 mm OD) were kindly provided by Dr. Dellon. The therapeutic drug fluticasone propionate (FTS) was purchased from Letco medical (Decatur, Al, USA). All materials were stored as directed by the supplier and used as received.

HeLa (ATCC® CCL-2™) cells were kindly provided by Dr. Chris Luft, University of North Carolina, Chapel Hill. HeLa cells were cultured in Dulbecco's Modified Eagle's Medium from Gibco Gaithersberg MD, USA) with 10% fetal calf serum from Gibco (Gaithersberg, USA) and 100 units/mL each of penicillin and streptomycin from Life Technologies (Grand Island, NY, USA). Cell lines were maintained at 37 ◦C in a humidified atmosphere containing 5% CO2, and ATCC guidelines were used for sub-culturing cells. For quantification of fluticasone in pig serum and esophageal homogenate in in vivo and ex vivo studies, pig plasma (K2EDTA anti-coagulant was purchased from BioIVT (Hicksville, NY, USA), fluticasone propionate, dimethylsulfoxide, and zinc sulfate solution were purchased from Sigma (St. Louis, MO, USA); d5-fluticasone propionate was purchased from Toronto Research Chemicals (North York, ON, CA); ammonium hydroxide, methanol, and acetonitrile were purchased from VWR (Radnor, PA, USA); and HLB µElution plates were purchased from Waters (Milford, MA, USA)
