Deposition of zwitterionic polymer brushes in a dense gas medium.
Poly(sulfobetaine methacrylate) (PSBMA) films known for their resistance to nonspecific protein adsorption, cell/bacterial adhesion and biofilm formation were produced by surface initiated polymerization on a silicon surface via a batch reaction system in CO2 expanded liquid (CO2-EL) medium. Atom transfer radical polymerization (ATRP) was carried out using 2,2'-bipyridyl as ligand and CuBr as a catalyst in water/methanol mixture with trichloro[4-(chloromethyl)phenyl]silane (CMPS) used as the initiating species. The films were grown in the CO2-EL environment at a range of conditions and thickness up to 10nm. In contrast to films produced by conventional solvent systems at atmospheric pressure, the polymer films grown by the CO2-EL process showed uniform thickness and pin-hole free topography. Most importantly, the CO2-EL processed PSBMA films showed no trace of copper (used as the catalyst), thus obviating the need for post-deposition processing and avoiding adverse effects of the metal leaching during service. Finally, PSBMA films from both the conventional and CO2-EL processes were exposed to Human mesenchymal stem cells (hMSCs) and the results showed that, while in both the cases the cell proliferation rate was inhibited by the charged polymeric brush surface, the CO2-EL-processed brush exhibited inhibition to a larger extent due to the reduced occurrence of pinholes. The process can be easily exploited effectively when carrying out surface initiated polymerization on non-flat topographies, such as in trenches and nanostructured features with high aspect ratios.
Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602, Singapore. Electronic address: puniredds@imre.a-star.edu.sg.
Sreenivasa Reddy
SR
Puniredd
Environmental & Water Technology, Centre of Innovation, Ngee Ann Polytechnic, Singapore 599489, Singapore.
Sundaramurthy
S
Jayaraman
Center for Nanofibers and Nanotechnology, Nanoscience and Nanotechnology Initiative, National University of Singapore, Singapore 117576, Singapore.
Chinnasamy
C
Gandhimathi
Center for Nanofibers and Nanotechnology, Nanoscience and Nanotechnology Initiative, National University of Singapore, Singapore 117576, Singapore.
Seeram
S
Ramakrishna
Center for Nanofibers and Nanotechnology, Nanoscience and Nanotechnology Initiative, National University of Singapore, Singapore 117576, Singapore.
Jayarama Reddy
JR
Venugopal
Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117576, Singapore.
Tin Wei
TW
Yeo
Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602, Singapore.
Shifeng
S
Guo
Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602, Singapore.
Robert
R
Quintana
Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), 3 Research Link, Singapore 117602, Singapore; Laboratory of Technological Processes, Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland.
Dominik
D
Jańczewski
Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117576, Singapore. Electronic address: chesmp@nus.edu.sg.
M P
MP
Srinivasan
D001672:Biocompatible Materials / Q000737:chemistry* / Q000378:metabolism; D002245:Carbon Dioxide / Q000737:chemistry; D002460:Cell Line; D049109:Cell Proliferation; D002470:Cell Survival; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology; D008689:Methacrylates / Q000737:chemistry* / Q000378:metabolism; D058105:Polymerization; D013499:Surface Properties
D001672:Biocompatible Materials; D008689:Methacrylates; C521589:sulfobetaine methacrylate polymer; D002245:Carbon Dioxide
CO(2)-expanded liquid medium; Polymer brush; Zwitter ions