In vivo biocompatibility of porous and non-porous polypyrrole based trilayered actuators
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Trilayered polypyrrole (PPy) actuators have high stress density, low modulus and have wide potential biological applications including use in artificial muscles and in limb prosthesis after limb amputation. This article examines the in vivo biocompatibility of actuators in muscle using rabbit models. The actuators were specially designed with pores to encourage tissue in growth; this study also assessed the effect of such pores on the stability of the actuators in vivo. Trilayered PPy actuators were either laser cut with 150 µm pores or left pore-less and implanted into rabbit muscle for 3 days, 2 weeks, 4 weeks and 8 weeks and retrieved subsequently for histological analysis. In a second set of experiments, the cut edges of pores in porous actuator strips were further sealed by PPy after laser cutting to further improve its stability in vivo. Porous actuators with and without PPy sealing of pore edges were implanted intramuscularly for 4 and 8 weeks and assessed with histology. Pore-less actuators incited a mild inflammatory response, becoming progressively walled off by a thin layer of fibrous tissue. Porous actuators showed increased PPy fragmentation and delamination with associated greater foreign body response compared to pore-less actuators. The PPy fragmentation was minimized when the pore edges were sealed off by PPy after laser cutting showing less PPy debris. Laser cutting of the actuators with pores destabilizes the PPy. This can be overcome by sealing the cut edges of the pores with PPy after laser. The findings in this article have implications in future design and manufacturing of PPy actuator for use in vivo.
This work was funded through the Australian Orthopaedic Association (AOA) research foundation grant. The authors would like to acknowledge the Australian National Fabrication Facility (ANFF) Materials Node at Wollongong for use of their facilities
Compliance with ethical standards
Conflict of interest
The authors declare that they have no competing interests.
- 1.Dillingham TR, Pezzin LE, MacKenzie EJ. Limb amputation and limb deficiency: epidemiology and recent trends in the United States. South Med J. 2002;95(8):875–83.Google Scholar
- 5.Hollerbach JM, Hunter IW, Ballantyne J. A comparative analysis of actuator technologies for robotics. In: Khatib O, Craig JJ, Lozano-Pérez T editors. The robotics review 2. Cambridge, MA, USA: MIT Press; 1992. p. 299–342.Google Scholar
- 6.Samatham R, Kim KJ, Dogruer D, Choi HR, Konyo M, Madden JD et al. Active Polymers: An Overview. In: Kim KJ, Tadokoro S editors. Electroactive Polymers for Robotic Applications Artificial Muscles and Sensors. 1st edn.: London: Springer-Verlag; 2007. p. 1–36.Google Scholar
- 13.Kiefer R, Mandviwalla X, Archer R, Tjahyono SS, Wang H, MacDonald B et al., editors. The application of polypyrrole trilayer actuators in microfluidics and robotics2008Google Scholar
- 18.Stewart E, Kobayashi NR, Higgins MJ, Quigley AF, Jamali S, Moulton SE, et al. Electrical stimulation using conductive polymer polypyrrole promotes differentiation of human neural stem cells: a biocompatible platform for translational neural tissue engineering. Tissue Eng C, Methods. 2015;21(4):385–93. http://doi.org/10.1089/ten.TEC.2014.0338 CrossRefGoogle Scholar
- 21.Wang Z, Roberge C, Dao LH, Wan Y, Shi G, Rouabhia M, et al. In vivo evaluation of a novel electrically conductive polypyrrole/poly(D,L-lactide) composite and polypyrrole-coated poly(D,L-lactide-co-glycolide) membranes. J Biomed Mater Res A. 2004;70(1):28–38. http://doi.org/10.1002/jbm.a.30047 CrossRefGoogle Scholar
- 22.Schmidt CE, Shastri VR, Vacanti JP, Langer R. Stimulation of neurite outgrowth using an electrically conducting polymer. Proc Natl Acad Sci. 1997;94(17):8948-53Google Scholar