Ultrasound Luminescence Chemical Imaging: A Tool for Detection of Implant Infection via Monitoring of pH Changes at Implant Surface

Abstract

<p>Using ultrasound luminescent chemical imaging (ULCI) technique we<i> </i>imaged changes in the luminescence spectra of the ultrasound luminescent film modulated by a pH sensitive dye coating in different pH environments through a light scattering media. Our results show that high resolution images can be obtained through scattering media, and that the ultrasound luminescent film could be modulated by the pH sensitive dye.</p>

Development of pH‐Sensitive Film for Detection of Implant Infection via Ultrasound Luminescent Chemical Imaging

“…After initial excitation with 395 nm light, ultrasound excitation produces a ≈23x increase in luminescence intensity compared to when the ultrasound is switched OFF. [22] mechanoluminescence can be turned ON and OFF by pulsing the ultrasound beam as a function of time, as shown in Video S1 (Supporting Information). When the ultrasound is turned ON, a visible bright spot is observed on the film indicating a higher emission intensity, and when it is switched OFF, the emission decreases, and the spot is no longer visible to the naked eye.…”

“…Importantly, the spatially separated reference region on the implant accounts for most of these optical transmission issues as long as Vertical lines evident in these images are due to ultrasound modulation at 2 Hz (1 mm s −1 scan rate). [22] the tissue is relatively uniform between the reference and sensor regions. Our previous studies also demonstrate that optical absorption at 620 and 700 nm could be detected through 1 cm of skin and tissue in both live rabbits and a human cadaveric leg.…”

“…The function generator was programmed to output a 5 V square wave with a frequency of 2 Hz. [22] Pre-Processing of Data: Data included videos, spectra, and ULCI images. The videos and photos used the standard camera settings; the spectra were normalized as follows: In Figure 4a, spectra were normalized to 700 nm from pH 4.…”

“…[21] Herein we introduce Ultrasound Luminescent Chemical Imaging (ULCI), a technique to monitor local pH at the sur-face of a modified implant during infection (Figure 1). [22] Specifically, to image or map a target area via a point-by-point raster scanning with the ULCI system, we modified the X-ray Excited Luminescent Chemical Imaging (XELCI) [12,19,23,24] system that has been successfully used to image pH in human cadaveric tibia [19] and live rabbits. [25] The XELCI system produces high resolution images, but uses a relatively expensive focused X-ray source, and the associated radiation dose that limits repeated measurements.…”

“…d) Spectra from SrAl 2 O 4 :Eu, Dy film as ultrasound is pulsed ON and OFF. After initial excitation with 395 nm light, ultrasound excitation produces a ≈23x increase in luminescence intensity compared to when the ultrasound is switched OFF [22].…”