Fatima Mumtaz,Chaoshi Chen,Haikun Zhu,Chao Pan,Yanmei Wang
In this work, poly(2-methyl-2-oxazoline-random-glycidyl methacrylate) (PMOXA-r-GMA) and poly(acrylic acid)-block-poly(glycidyl methacrylate) (PAA-b-PGMA) copolymers were synthesized via cationic ring-opening polymerization (CROP) of 2-methyl-2-oxazoline (MOXA) and reversible addition-fragmentation chain transfer (RAFT) polymerization of acrylic acid (AA) followed by their random and block copolymerization with glycidyl methacrylate (GMA), respectively, and then characterized carefully. PMOXA/PAA based coatings were then prepared by simply spin coating the mixture of PMOXA-r-GMA and PAA-b-PGMA copolymer solutions onto silicon/glass substrates followed by annealing at 110 °C. The coatings were rigorously characterized by using X-ray photoelectron spectroscopy (XPS), the static water contact angle (WCA) test, ellipsometry and atomic force microscopy (AFM). The results demonstrated that the coating based mixed PMOXA/PAA brushes with desired surface composition could be attained by simply maintaining their percentage in the mixture of PMOXA-r-GMA and PAA-b-PGMA copolymer solutions. Finally, the switchable behavior of PMOXA/PAA based coatings toward bovine serum albumin (BSA) adsorption was investigated by fluorescein isothiocyanate-labelled BSA (FITC-BSA) assay and quartz crystal microbalance with dissipation monitoring (QCM-D), which indicated that the coating based mixed PMOXA/PAA brushes could control BSA adsorption/desorption from very low to high amount (>90% desorption) through adjusting the composition of PMOXA-r-GMA and PAA-b-PGMA solution used in preparing PMOXA/PAA based coatings upon pH and ionic strength change. Furthermore, PMOXA/PAA based coatings displayed efficient repeatability of reversible BSA adsorption/desorption cycles.
In this study we report design of stimuli-responsive coating based on poly(2-methyl-2-oxazoline-random-glycidyl methacrylate) (PMOXA- r -GMA) comb copolymer and poly(acrylic acid)-block-poly(glycidyl methacrylate) (PAA- b -PGMA) block copolymers and scrutinize its ability to control protein adsorption. Firstly, PMOXA/PAA based coatings were prepared by simply spin coating the mixture of PMOXA- r -GMA and PAA- b -PGMA copolymer solutions onto silicon substrates followed by annealing at 110 °C. Then coatings were rigorously characterized by X-ray photoelectron spectroscopy (XPS), the static water contact angle (WCA) test, ellipsometry and atomic force microscopy (AFM). After that, the relationship of switchable behavior of PMOXA/PAA based coatings with PAA content and chain length was investigated through the change of thickness and WCA upon pH and ionic strength ( I ) trigger, which indicated that the change in thickness and WCA was triggered when PAA contents were increased as well as by increasing chain length of PAA in PMOXA/PAA based coatings. Finally, real-time adsorption/desorption of lysozyme (Lyso) on PMOXA/PAA based coatings was monitored using quartz crystal microbalance with dissipation monitoring (QCM-D). The results showed that the Lyso adsorption amount was increased upon increasing chain length and contents of PAA in PMOXA/PAA based coatings. The adsorbed Lyso was then efficiently desorbed by changing pH and I of medium with the maximum desorption (> 90% desorption percentage) observed for the suitable ratio of PMOXA and PAA while chain length of PAA was kept longer than that of PMOXA. Furthermore, the prepared coatings were found to repeatedly adsorb and desorb Lyso for four successive cycles of adsorption/desorption, which confirmed the stability of prepared coatings.