The effect of physiologic aqueous solutions on the perovskite material lead-lanthanum-zirconium titanate (PLZT): potential retinotoxicity

Abstract

Context: Perovskite compounds, including lead-lanthanum-zirconium titanate (PLZT), have wide technological application because of their unique physical properties. The use of PLZT in neuro-prosthetic systems, such as retinal implants, has been discussed in a number of publications. Since inorganic lead is a retinotoxic compound that produces retinal degeneration, the long-term stability of PLZT in aqueous biological solutions must be determined.

Objective: We evaluated the stability and effects of prolonged immersion of a PLZT-coated crystal in a buffered balanced salt solution.

Materials and methods: Scanning Electron Microscopy and Electron Dispersive Spectroscopy (EDS) using a JEOL JSM 5410 microscope equipped with EDS were utilized to evaluate the samples before and after prolonged immersion.

Results: We found that lead and other constituents of PLZT leached into the surrounding aqueous medium.

Discussion: By comparing the unit cell of PLZT with that of CaTiO₃, which has been found to react with aqueous fluids, Lead is in the same site in PLZT as Ca is in CaTiO₃. It is thus reasonable that PLZT will react with aqueous solutions.

Conclusion: The results suggest that PLZT must either be coated with a protective layer or is not appropriate for long-term in vivo or in vitro biological applications.

Keywords::

• Lead
• retina
• toxicity
• aqueous