The inhibition of neuronal calcium ion channels by trace levels of yttrium released from carbon nanotubes.

LORIN M. JAKUBEK; SPIRO MARANGOUDAKIS; JESICA RAINGO; XINYUAN LIU; DIANE LIPSCOMBE; ROBERT H. HURT

BIOMATERIALS

ELSEVIER SCI LTD

Lugar: Amsterdam; Año: 2009 vol. 30 p. 6351 - 6357

0142-9612

a b s t r a c tCarbon nanotubes (CNTs) are used with increasing frequency in neuroengineering applications. CNTscaffolds are used to transmit electrical stimulation to cultured neurons and to control outgrowth andbranching patterns of neurites. CNTs have been reported to disrupt normal neuronal function includingalterations in endocytotic capability and inhibition of ion channels. Calcium ion channels regulatenumerous neuronal and cellular functions including endo and exocytosis, neurite outgrowth, and geneexpression. Strong CNT interactions with neuronal calcium ion channels would have profound biologicalimplications. Here we show that physiological solutions containing CNTs inhibit neuronal voltage-gatedcalcium ion channels in a dose-dependent and CNT sample-dependent manner with IC50 as low as1.2 mg/ml. Importantly, we demonstrate that the inhibitory activity does not involve tubular graphene aspreviously reported, but rather very low concentrations of soluble yttrium released from the nanotubegrowth catalyst. Cationic yttrium potently inhibits calcium ion channel function with an inhibitoryefficacy, IC50, of 0.07 ppm w/w. Because of this potency, unpurified and even some reportedly ‘‘purified’’CNT samples contain sufficient bioavailable yttrium to inhibit channel function. Our results haveimportant implications for emerging nano-neurotechnology and highlight the critical role that tracecomponents can play in the biological response to complex nanomaterials.2009 Elsevier Ltd. All rights reserved.