A simple method to improve the reliability of iontophoretic administration of tracer substances

Microiontophoresis is a widely used technique for depositing tracer materials into the central nervous system for neuroanatomical experiments. However, the reliability of iontophoretic injection is often less than optimal. Coating the lumen of glass micropipettes with silicone to reduce surface tension reduced the incidence of failure for iontophoretic deposition of wheat germ agglutinin-horseradish peroxidase (WGA-HRP) from 40% to zero. Similar results were observed with other tracer substances. Siliconizing the internal surface of glass micropipettes can significantly improve the reliability of iontophoretic deposition.