Poly(ethylene terephthalate) films coated with antimicrobial gelatin/chondroitin sulfate polyelectrolyte multilayers containing ionic liquids

Abstract

Gelatin (GE) and chondroitin sulfate (CS) polyelectrolyte multilayers (PEMs) with or without ionic liquids (ILs) are assembled on oxidized poly(ethylene terephthalate) (PET), using the layer-by-layer (LbL) approach. The ILs associated with the PEMs include 1-n-hexadecyl-3-methylimidazolium chloride (C16MImCl), 1-n-hexadecyl-3-methylimidazolium methanesulfonate (C16MImMeS), and 1-n-hexadecyl pyridinium chloride monohydrate (C16PyrCl.H2O). The ILs are associated with PEMs for the first time. The ILs are dissolved in an aqueous GE solution and then associated with CS by the layer-by-layer approach. The alternating deposition of GE or GE/ILs and CS multilayers on the oxidized PET results in durable surface coatings. The oxidized PET and PEMs are characterized by atomic force microscopy (AFM), scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS), spectroscopic ellipsometry, and water contact angle (WCA) measurements. The GE/CS IL PEM coatings reveal higher wettability (WCA between 41 and 45°) and roughness (root mean square, Rq, values between 74.5 and 89.1 nm) than the unmodified PET (WCA of 90.9° and surface roughness of 26.9 nm). The PEMs are homogeneous surface coatings with durability after exposure to phosphate-buffered saline (pH 7.4) for 24 h. The ILs impart low minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) against Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa). The MIC and MBC are lower than 0.625 μg/mL against P. aeruginosa. The CS and GE and the GE/CS PEM do not provide any antimicrobial effect. However, the GE/CS IL PEMs show high antimicrobial capacity, preventing the attachment and growth of microbial cells. The GE/CS IL PEMs are durable, bactericidal, and anti-adhesive surfaces for PET.