Conductive and Piezoelectric Materials

Piezoelectric (Aebischer et al. 1987) materials have also been shown to enhance neural cell function without any external electrical stimulation. Conductive polymers, typically PPy, have been shown to be a permissive substrate for axonal growth in vitro and in vivo. However, studies have shown that an electrical stimulus applied to the conducting polymer was needed to enhance axon outgrowth to levels beyond that which would be expected on an inert, biocompatible polymer (Schmidt et al. 1997; Zhang et al. 2006). NGCs fabricated from an electrically conductive, biodegradable polymer of PPy and poly(D,L-lactide-co-epsilon-caprolactone) (PDLLA/ CL) were comparable to nonconductive NGCs made of PDLLA/CL alone (Zhang et al. 2006). A current intensity of 1.7-8.4 mA/cm led to the greatest enhancement of neurite outgrowth on the conductive PDLLA/CL and PPy surfaces. Interestingly, the authors comment on the challenges associated with developing a power supply for the application of such an electrical stimulus. Piezoelectric materials produce a transient electrical response when they are mechanically deformed. As a result, an electrical stimulus may be possible without direct connection to a voltage source. Though an electrical stimulus is a known stimulatory cue for neural development, few studies have investigated neural tissue engineering applications of piezoelectric materials. A study investigating the piezoelectric properties of a piezoelectric PVDF polymer measured a 1,200 Hz oscillating voltage with a peak of 2.5 mV (Valentini et al. 1992). Voltage output was due to the mechanical stress caused by vibrations of the incubator shelf on which the measurements were taken. This piezoelectric response enhanced neural cell (Nb2a) differentiation and neurite outgrowth compared to non-piezoelectric controls. In another study regarding electrically active materials, a high voltage (8-24 kV) was applied to PLGA films and NGCs prior to cell culture experiments or implantation to produce a surface charge on the polymer (Bryan et al. 2004). The number of cells with neurites and the number of myelinated axons was significantly increased.

Diabetes 2

Diabetes 2

Diabetes is a disease that affects the way your body uses food. Normally, your body converts sugars, starches and other foods into a form of sugar called glucose. Your body uses glucose for fuel. The cells receive the glucose through the bloodstream. They then use insulin a hormone made by the pancreas to absorb the glucose, convert it into energy, and either use it or store it for later use. Learn more...

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