Multilayered Thin Films from Boronic Acid-Functional Poly(amido amine)s as Drug-Releasing Surfaces

Purpose To evaluate the potential of poly(amido amine)-based multilayered thin films in surface mediated drug release. Methods Multilayered thin films were prepared from copolymers of phenylboronic acid-functional poly(amido amine)s and chondroitin sulfate (ChS) in the presence of Alizarin Red S (ARS) as a reporter molecule. Multilayer buildup and ARS incorporation were evaluated with UV–vis spectroscopy. Glucose responsiveness of the multilayers was investigated. Finally, cellular uptake of ARS by COS-7 cells grown on the films was assessed. Results Multilayers based on alcohol containing polymers (ABOL-BA-PAA#ChS + ARS) displayed higher ARS incorporation than multilayers based on amine-containing polymers (DAB-BA-PAA#ChS + ARS). At physiological pH, a swift initial release of up to ~40% of the ARS content was observed during the first 12 h of incubation, followed by a much slower, gradual release of ARS. The multilayers were further evaluated by culturing COS-7 cells on top of multilayer-coated well plates. Cellular uptake of the fluorescent ARS-boronate ester was quantified through flow cytometry, and a maximum uptake of up to 30% was observed. Confocal microscopy confirmed the presence of ARS-boronate ester-containing particles in the nuclei of cells. Conclusions The investigated multilayered thin films are effective in surface-mediated delivery of the model compound ARS. These multilayered surfaces are promising as drug-releasing delivery surface for coating stents, prostheses, and other implants.