Synthesis and anti-fouling properties of zwitterionic poly( l -glutamic acid)

Zwitterionic polymers are frequently used as non-fouling materials for surface modification with following application in medical devices, implants or areas of our lives such as food, water, and energy. Here, authors report the synthesis of zwitterionic poly( l -glutamic acid) copolymer bearing sulfobetaine via combining the ring-opening polymerization of N -carboxyanhydride of γ-benzyl- l -glutamate and grafting reaction of propargylamine, tyramine, and 3-(dimethylamino)-1-propylamine to the polymer backbone with subsequent reaction of 1,3-propanesultone leading to the formation of zwitterionic poly( l -glutamic acid) containing sulfobetaine groups. Zwitterionic properties of the copolymer are represented by positively charged quaternary ammonium groups and negatively charged sulfobetaine moieties. The chemical structure of the synthesized zwitterionic poly( l -glutamic acid) was characterized by 1 H NMR, FTIR, and UV/Vis spectroscopy. The zwitterionic abilities of copolymer were confirmed by zeta potential measurements. The zeta potential of zwitterionic polymer decreased from + 15 mV to − 19 mV upon stepwise pH increases from 2 to 11. The surface properties such as hydrophilicity and non-fouling abilities were tested by contact angle analysis and surface plasmon resonance technique, respectively. The prepared material indicates the formation of highly hydrophilic surfaces with relatively low contact angle (26°) and remarkable anti-protein adsorption functions reflected in lower resonance wavelength shifts from SPR sensogram. Results of this work show the importance of the developed biodegradable zwitterionic poly( l -glutamic acid)-based coatings for applications in various biomedical fields. Graphical abstract Novel zwitterionic sulfobetaine poly( l -glutamic acid)-based copolymer is prepared by the ring-opening polymerization of N -carboxyanhydride with following grafting reaction and subsequent introducing of the sulfobetaine groups. The developed biocompatible material indicates outstanding anti-fouling abilities and high hydrophilicity. The observed properties are promising for the development of non-fouling materials with biomedical applications