Electroactive hybrid hydrogels, composed of single-walled carbon nanotubes, polypyrrole, and poly(ethylene glycol) diacrylate–polyacrylamide, were synthesized on titanium-mesh electrodes via interfacial polymerization. The modified electrodes can be used as controlled drug delivery system by applying an external electrical stimulation of cyclic voltammetry. Investigations revealed that single-walled carbon nanotubes acted as nucleators in the hybrid hydrogel and facilitated the formation of a continuous and uniform polypyrrole coating. Simultaneous incorporation of single-walled carbon nanotubes and polypyrrole improved not only the electrochemical performance but also the drug loading capacity of the hydrogel. Study of dexamethasone release triggered by cyclic voltammetry indicated that the hybrid hydrogel exhibited good electrochemical stability, a high drug loading capacity, and a linear and sustaining drug release profile, making the modified electrode a novel high-performance drug delivery device. Moreover, in vitro experiments demonstrated that dexamethasone released from the modified electrodes well retained its bioactivity, having the same effect on reducing lipopolysaccharide-induced macrophage activation as the intact commercially available dexamethasone. More important, the obtained modified electrodes possessed good biocompatibility with neural cells, demonstrated by in vitro cell culture.
CoganSF. Neural stimulation and recording electrodes. Annu Rev Biomed Eng2008; 10: 275–309.
2.
KahanJUrnerMMoranR. Resting state functional MRI in Parkinson’s disease: the impact of deep brain stimulation on “effective” connectivity. Brain2014; 137(4): 1130–1144.
3.
PinyonJLTadrosSFFroudKE. Close-field electroporation gene delivery using the cochlear implant electrode array enhances the bionic ear. Sci Transl Med2014; 6(233): 233ra54.
4.
MorrisGLGlossDBuchhalterJ. Evidence-based guideline update: vagus nerve stimulation for the treatment of epilepsy. Report of the Guideline Development Subcommittee of the American Academy of Neurology. Neurology2013; 81(16): 1453–1459.
5.
FrostCMCedernaPSMartinDC. Decellular biological scaffold polymerized with PEDOT for improving peripheral nerve interface charge transfer. In: 2014 36th annual international conference of the IEEE Engineering in Medicine and Biology Society (EMBC), Chicago, IL, 26–30 August 2014, pp. 422–425. Piscataway, NJ: IEEE.
6.
GrillWMNormanSEBellamkondaRV. Implanted neural interfaces: biochallenges and engineered solutions. Annu Rev Biomed Eng2009; 11: 1–24.
7.
WadhwaRLagenaurCFCuiXT. Electrochemically controlled release of dexamethasone from conducting polymer polypyrrole coated electrode. J Control Release2006; 110(3): 531–541.
8.
LeprinceLDogimontAMagninD. Dexamethasone electrically controlled release from polypyrrole-coated nanostructured electrodes. J Mater Sci Mater Med2010; 21(3): 925–930.
9.
KozaiTDYGugelZLiX. Chronic tissue response to carboxymethyl cellulose based dissolvable insertion needle for ultra-small neural probes. Biomaterials2014; 35(34): 9255–9268.
10.
PolikovVSTrescoPAReichertWM. Response of brain tissue to chronically implanted neural electrodes. J Neurosci Methods2005; 148(1): 1–18.
11.
McConnellGCReesHDLeveyAI. Implanted neural electrodes cause chronic, local inflammation that is correlated with local neurodegeneration. J Neural Eng2009; 6(5): 056003.
12.
AzemiELagenaurCFCuiXT. The surface immobilization of the neural adhesion molecule L1 on neural probes and its effect on neuronal density and gliosis at the probe/tissue interface. Biomaterials2011; 32(3): 681–692.
13.
Guiseppi-ElieAWilsonAMSujdakAR. Electroconductive hydrogels: novel materials for the controlled electrorelease of bioactive peptides. Polymer Prepr1997; 38(2): 608–609.
JustinGGuiseppi-ElieA. Electroconductive blends of poly (HEMA-co-PEGMA-co-HMMA-co-SPMA) and poly (Py-co-PyBA): in vitro biocompatibility. J Bioact Compat Polym2010; 25(2): 121–140.
16.
KimDHWilerJAAndersonDJ. Conducting polymers on hydrogel-coated neural electrode provide sensitive neural recordings in auditory cortex. Acta Biomater2010; 6(1): 57–62.
17.
RaoLZhouHLiT. Polyethylene glycol-containing polyurethane hydrogel coatings for improving the biocompatibility of neural electrodes. Acta Biomater2012; 8(6): 2233–2242.
18.
GreenRABaekSPoole-WarrenLA. Conducting polymer-hydrogels for medical electrode applications. Sci Technol Adv Mat2010; 11(1): 014107.
19.
NistorMTVasileCChiriacAP. Biocompatibility, biodegradability, and drug carrier ability of hybrid collagen-based hydrogel nanocomposites. J Bioact Compat Polym2013; 28(6): 540–556.
20.
WeaverCLLaRosaJMLuoX. Electrically controlled drug delivery from graphene oxide nanocomposite films. ACS Nano2014; 8(2): 1834–1843.
21.
BalintRCassidyNJCartmellSH. Conductive polymers: towards a smart biomaterial for tissue engineering. Acta Biomater2014; 10(6): 2341–2353.
22.
PillayVTsaiTSChoonaraYE. A review of integrating electroactive polymers as responsive systems for specialized drug delivery applications. J Biomed Mater Res A2014; 102(6): 2039–2054.
23.
CheongGLMLimKSJakubowiczA. Conductive hydrogels with tailored bioactivity for implantable electrode coatings. Acta Biomater2014; 10(3): 1216–1226.
24.
IndermunSChoonaraYEKumarP. An interfacially plasticized electro-responsive hydrogel for transdermal electro-activated and modulated (TEAM) drug delivery. Int J Pharm2014; 462(1): 52–65.
25.
ZhaoWGlavasLOdeliusK. Facile and green approach towards electrically conductive hemicellulose hydrogels with tunable conductivity and swelling behavior. Chem Mater2014; 26(14): 4265–4273.
26.
SvirskisDTravas-SejdicJRodgersA. Electrochemically controlled drug delivery based on intrinsically conducting polymers. J Control Release2010; 146(1): 6–15.
27.
AbidianMRKimDHMartinDC. Conducting-polymer nanotubes for controlled drug release. Adv Mater2006; 18(4): 405–409.
28.
PengCJinJChenGZ. A comparative study on electrochemical co-deposition and capacitance of composite films of conducting polymers and carbon nanotubes. Electrochim Acta2007; 53(2): 525–537.
29.
LuoXMatrangaCTanS. Carbon nanotube nanoreservior for controlled release of anti-inflammatory dexamethasone. Biomaterials2011; 32(26): 6316–6323.
30.
YueZMoultonSECookM. Controlled delivery for neuro-bionic devices. Adv Drug Deliv Rev2013; 65(4): 559–569.
XiaoYHeLCheJ. An effective approach for the fabrication of reinforced composite hydrogel engineered with SWNTs, polypyrrole and PEGDA hydrogel. J Mater Chem2012; 22(16): 8076–8082.
