Liquid- and solid-state high-resolution NMR methods for the investigation of aging processes of silicone breast implants

To investigate aging processes of silicone gel breast implants, which nay include migration of free unreacted material from the gel and rubber to local (e.g. connective tissue capsule) or distant sites in the body, chemical alteration of the polymer and infiltration of body compounds, various approaches of multinuclear nuclear magnetic resonance (NMR) experiments (Si-29, C-13, H-1) were evaluated. While Si-29, C-13, and H-1 solid-state magic angle spinning (MAS) NMR techniques performed on virgin and explanted envelopes of silicone prostheses provided only limited information, high-resolution liquid-state NMR techniques of CDCl3 extracts were highly sensitive analytical tools for the detection of aging related changes in the materials. Using 2D H-1, H-1 correlation spectroscopy (COSY) and Si-29, H-1 heteronuclear multiple bond coherence (HMBC) experiments with gradient selection, it was possible to detect lipids (mainly phospholipids) as well as silicone oligomer species in explanted envelopes and gels. Silicone oligomers were also found in connective tissue capsules, indicating that cyclic polysiloxanes can migrate from intact implants to adjacent and distant sites. Furthermore, lipids can permeate the implant and modify its chemical composition. (C) 2002 Elsevier Science Ltd. All rights reserved.