Migration and chemical modification of silicone in women with breast prostheses

Chemical and physicochemical properties of the high cohesive silicone gel from Poly Implant Prothèse (PIP) breast prostheses after explantation: a preliminary, comparative analytical investigation

Aim of this work was to gain a deeper insight into the analytical profile of the macromolecular and LMW fractions of polymeric silicones present in breast implants. The study was conducted on silicone gel samples from (i) breast prostheses (Poly Implant Prothèse, PIP) explanted from a patient that needed their therapeutical removal, (ii) from a virgin Mc Ghan 410 MX prosthesis and (iii) from a sample of technical-grade non-cohesive silicone. The gels were analysed using rheological techniques, attenuated total reflectance infrared spectroscopy (ATR-FT-IR), nuclear magnetic resonance ((1)H NMR), gas chromatography coupled to mass spectrometry (GC-MS) and flow injection electrospray mass spectrometry (FI-ESI-MS). Our results demonstrate that, compared to the virgin McGhan gel, the silicone present the PIP prostheses lacks a significant part of the cross-linking sites necessary for the high-cohesive properties of the gel, significant amounts of cholesterol have been absorbed from the breast tissue by the silicone material, demonstrating the lack of impermeability of its elastomer shell. The potential implications and consequences of these analytical results are discussed.

Assessment of silicone gel breast implant biodurability by NMR and EDS techniques

In a study using explanted gel breast implants and appropriate nonimplanted controls, we examined silicone biodurability after long-term implantation. Using NMR spectroscopy, as well as NMR relaxometry measurements (T(2)), no evidence of hydrolysis or other chemical degradation of the cross-linked silicone matrix was observed in specimens from an early breast implant model (Cronin) explanted after 32 years in vivo or a more recent Silastic II model after 13 years in vivo. In addition, no appreciable differences were seen in T(2) relaxation times comparing explanted breast implants to suitably-matched nonimplanted controls, further underscoring the biostability of the cross-linked silicone shell and gel. Our T(2) data and resultant interpretations differ from a 2004 report by the NMR lab at the University of Münster, highlighting the importance of suitable nonimplanted controls and sample preparation. Energy dispersive spectroscopy (EDS) was also performed, confirming the persistence of a fluorosilicone layer inside the elastomer shells of Silastic II implants.

Limits of detection of polydimethylsiloxane in (29)Si NMR spectroscopy

Limits of detection for neat poly(dimethylsiloxane) (PDMS), as detected via (29)Si NMR spectroscopy, were determined by the IUPAC, graphical, and propagation of errors methods from calibration curves obtained using a 7.05 Tesla superconducting magnet equipped with a magic angle spinning (MAS) NMR probe. Under conditions permitting full relaxation of the nuclear spins (recycle time >150 sec), the limit of detection with 128 transients was 1.7, 2.2, and 3.7 mg PDMS (23, 30, and 50 micromoles elemental Si) for the IUPAC, graphical, and propagation of errors methods, respectively. A higher limit of detection results when additional sources of uncertainty are considered. From the strict dependence of the limit of detection on the inverse of the square root of the number of transients signal-averaged, it is possible to extrapolate to a limit of detection of 183 microg PDMS (2.47 micromoles elemental Si) for a 24-hr signal averaging period. This limit of detection is 3 orders of magnitude higher than silicon levels found in human blood.