In Vivo Ultrasonic Detection of Polyurea Crosslinked Silica Aerogel Implants

Abstract

BackgroundPolyurea crosslinked silica aerogels are highly porous, lightweight, and mechanically strong materials with great potential for in vivo applications. Recent in vivo and in vitro studies have demonstrated the biocompatibility of this type of aerogel. The highly porous nature of aerogels allows for exceptional thermal, electric, and acoustic insulating capabilities that can be taken advantage of for non-invasive external imaging techniques. Sound-based detection of implants is a low cost, non-invasive, portable, and rapid technique that is routinely used and readily available in major clinics and hospitals.MethodologyIn this study the first in vivo ultrasound response of polyurea crosslinked silica aerogel implants was investigated by means of a GE Medical Systems LogiQe diagnostic ultrasound machine with a linear array probe. Aerogel samples were inserted subcutaneously and sub-muscularly in a) fresh animal model and b) cadaveric human model for analysis. For comparison, samples of polydimethylsiloxane (PDMS) were also imaged under similar conditions as the aerogel samples.Conclusion/significancePolyurea crosslinked silica aerogel (X-Si aerogel) implants were easily identified when inserted in either of the regions in both fresh animal model and cadaveric model. The implant dimensions inferred from the images matched the actual size of the implants and no apparent damage was sustained by the X-Si aerogel implants as a result of the ultrasonic imaging process. The aerogel implants demonstrated hyperechoic behavior and significant posterior shadowing. Results obtained were compared with images acquired from the PDMS implants inserted at the same location.

Synthesis and biomedical applications of aerogels: Possibilities and challenges

“…61 through series of in-vitro [44,198] and in-vivo [42,43] analysis. However, more works are still required for aerogels with various formulations to be applied in biological systems.…”

“…Ability to image an implant located in the peripheral region of the body with minimum hurts to the patient is an important part of designing of implant based biomaterial [42]. The acoustic absorption of aerogels has been recently considered for non-invasive and rapid imaging of aerogel-based implants located in the peripheral region of the body, especially in peripheral nervous system.…”

“…In this regard, ultrasonic properties of strong and highly porous PCSA aerogel implant in various insertion depths of Dawley rat and human cadaver model have been investigated [42].…”

In Vivo X-Ray Imaging of Phosphor-Doped PDMS and Phosphor-Doped Aerogel Biomaterials

“…Crosslinked silica aerogels have been investigated recently for biocompatibility and their potential to serve as a nerve growth scaffold [10][11][12][13]. A recent in vivo ultrasound study of crosslinked silica aerogels [14] demonstrated a detectable and unique acoustic response compared to the surrounding tissue. Other non-invasive imaging modalities such as X-ray imaging can provide valuable information about material properties and have not been investigated for crosslinked silica aerogels to date.…”

Polymer-Encapsulated Phosphor Particles forIn VivoPhosphor Luminescence Applications

“…An advantage of phosphor-based thermometry is that temperature-dependent luminescence can be measured from a distance and even through intervening scattering or partially absorbing media [6]. Elastomers from the family of polydimethylsiloxane (PDMS) are flexible and inert polymers with tunable chemical, physical, and electrical properties used in some cases for biomedical and in vivo applications [7]. The ability to ''dope'' these polymers creates a unique and versatile ''carrier'' for active materials such as phosphor particles routinely used in phosphor thermography [8].…”