In Vivo Quantitative Photoacoustic Diagnosis of Gastric and Intestinal Dysfunctions with a Broad pH-Responsive Sensor

Abstract

Gastrointestinal diseases affect many people in the world and significantly impair life quality and burden the healthcare system. The functional parameters of the gastrointestinal tract such as motility and pH can effectively reflect the changes of gastrointestinal activity in physiological and pathological conditions. Thus, a noninvasive method for real-time and quantitative measurement of gastrointestinal functional parameters in vivo is highly desired. At present, there are many strategies widely used for the diagnosis of gastrointestinal diseases in clinic, including X-ray barium meal examination, ultrasound imaging, radionuclide examination, endoscopy, etc. However, these methods are limited in determining the gastrointestinal status and cannot provide comprehensive quantitative information. Photoacoustic imaging (PAI) is a rapid noninvasive real-time imaging technique in which multiple types of functional and quantitative information can be simultaneously obtained. Unfortunately, very few ratiometric PAI contrast agents have been reported for quantification of gastrointestinal functional parameters in vivo. In this work, a broad, pH-responsive ratiometric sensor based on polyaniline and Au triangular nanoplates was developed. Utilizing the sensor as a contrast agent, PAI served as an all-in-one technique, accurately measuring the gastrointestinal functional parameters in a single test. Notably, this sensor was examined to be ultrasensitive with pH responses as fast as 0.6 s and durability as long as 24 h, and was repeatable and reversible for longitudinal monitoring. The quantitative results demonstrated a significant disorder in motility and decrease in pH for gastric and duodenal ulcers. Collectively, the combination of PAI and this broad pH-responsive sensor might be a promising candidate for quantitative diagnosis of gastrointestinal diseases.

Quantitative Photoacoustic Diagnosis and Precise Treatment of Inflammation In Vivo Using Activatable Theranostic Nanoprobe

“…However, conventional PAI cannot accurately quantify H 2 O 2 in the complex inflammatory microenvironment. Ratiometric PAI is more accurate and sensitive compared to the absolute intensity mode, [ 15 ] and has been used in monitoring the pH range, [ 15a ] methylmercury ions, [ 16 ] and reactive oxygen species (ROS) in biological tissues. [ 15f ] Since H 2 O 2 is a biomarker of inflammation, [ 4 ] quantifying H 2 O 2 in situ can not only diagnose inflammatory diseases but also elucidate its underling mechanisms.…”

Nanoparticle‐Based Activatable Probes for Bioimaging

“…The NP was shown to be ultrasensitive to pH, and response time was as fast as 0.6 s and durability as long as 24 h, which was repeatable for longitudinal monitoring. [ 27 ] Similarly, a self‐assembled charge‐transfer nanocomplex, which can accurately respond to pH change in the physiological range, was designed to be a new class of pH‐sensitive photoacoustic contrast agent that operates in the NIR‐II window. [ 28 ] Oxazine‐containing poly‐heterocycles with aggregation‐induced emission characteristics display remarkable fluorescence changes to protonation and deprotonation.…”

Design, Development, and Multi-Characterization of an Integrated Clinical Transrectal Ultrasound and Photoacoustic Device for Human Prostate Imaging

“…The strong intrinsic optical absorption of oxyhemoglobin (HbO 2 ) and deoxyhemoglobin (Hb) enables label-free imaging of individual blood vessels, facilitating the detection of angiogenesis, tissue blood volume, and blood oxygen saturation. Furthermore, the sensitivity and specificity of PAI can be enhanced by labeling tumor cells with exogenous contrast agents [ 19 , 20 ]…”