464 Full Paper wileyonlinelibrary.com Macromolecular Chemistry and Physics DOI: 10.1002/macp.201200464 Temperature-Responsiveness and Antimicrobial Properties of CNT–PNIPAM Hybrid Brush Films Katrina D. Pangilinan, Catherine M. Santos, Nicel C. Estillore, Debora F. Rodrigues,* Rigoberto C. Advincula* Temperature-responsive carbon nanotube (CNT)/poly( N-isopropylacrylamide) (PNIPAM) hybrid brush films were prepared by combining the layer-by-layer and surface-initiated polymeri- zation (LbL-SIP) techniques. Atom transfer radical polymerization (ATRP) is employed for the preparation of PNIPAM polymer brushes. Antibacterial activity of the CNT/PNIPAM films are investigated against Exiguobacterium sp. AT1b and Exiguobacterium sibiricum strains. Dead assay results show high microbial inactivation on coated surfaces with CNT films, while very low microbial inactivation is observed in PNIPAM films at all temperatures tested. The CNT–PNIPAM films, on the other hand, have antibacterial properties below 32 °C, which is below the lower critical solution temperature (LCST), but allows biofilm formation above the LCST. K. D. Pangilinan, Prof. R. C. Advincula Department of Macromolecular Science and Engineering, Case Western Reserve University, Cleveland, OH 44106, USA E-mail: rca41@case.edu Dr. C. M. Santos, Prof. D. F. Rodrigues Department of Civil and Environmental Engineering, University of Houston, Houston, TX 77204-5003, USA E-mail: dfrigiro@central.uh.edu Dr. N. C. Estillore Department of Chemistry, University of Houston, Houston, TX 77204-5003, USA A most common approach for the incorporation of antimicrobial properties onto surfaces is through incor- poration of drugs on the coating that are slowly released by diffusion. [3–5] The main problem with this approach is that as the drug is released, the concentration gradient of the drug to the biological device decreases. Therefore, the resistance of the device to microbial adherence may be compromised over time. [6] In addition, there are applications (e.g., corrosion and drug delivery) where antimicrobial property is desired only when specific conditions arises. Although the direct application of an antimicrobial coating on the surface can prevent bacterial colonization, there is a no guarantee that the effectiveness of antimicrobial action will be maintained nor that the coating will remain stable on the surface at the time that antimicrobial action is needed. Given that the surface will be exposed to various external and environmental factors all the time, there is a prob- able chance that the surface may not remain as equally effective by the time that antibacterial action is needed. Therefore, a coating where antimicrobial property can be controlled is highly preferred. The development of bioma- terials, which uses physicochemical stimulus to trigger 1. Introduction Over the last few years, the development of new materials with unique physicochemical characteristics for the pre- vention of bacterial colonization on biomedical devices and surfaces has been an integral part of synthetic coating strat- egies adopted by many investigators. [1,2] The conventional way of addressing this issue is to either create a microbial anti-adherent coating [1,2] or to incorporate antimicrobial properties onto surfaces [2] with the latter approach being more effective in preventing bacterial colonization. Macromol. Chem. Phys. 2013, 214, 464−469 © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim