Recent Progress on Near-Infrared Photoacoustic Imaging: Imaging Modality and Organic Semiconducting Agents

Abstract

Over the past few decades, the photoacoustic (PA) effect has been widely investigated, opening up diverse applications, such as photoacoustic spectroscopy, estimation of chemical energies, or point-of-care detection. Notably, photoacoustic imaging (PAI) has also been developed and has recently received considerable attention in bio-related or clinical imaging fields, as it now facilitates an imaging platform in the near-infrared (NIR) region by taking advantage of the significant advancement of exogenous imaging agents. The NIR PAI platform now paves the way for high-resolution, deep-tissue imaging, which is imperative for contemporary theragnosis, a combination of precise diagnosis and well-timed therapy. This review reports the recent progress on NIR PAI modality, as well as semiconducting contrast agents, and outlines the trend in current NIR imaging and provides further direction for the prospective development of PAI systems.

Effective photoacoustic absorption spectrum for collagen-based tissue imaging

“…8 Additionally, to delineate transparent organs such as lymph nodes, gastrointestinal tracts, and bladders, labeled imaging has also been performed using several contrast agents, such as indocyanine green or methylene blue. [9][10][11][12] The second window of the NIR (NIR-II) region, also called short-wave infrared region (SWIR, defined here as 1100 to 2000 nm), is of current interest due to the relative low levels of scattering and the high-maximum permissible exposure compared with the NIR-I region. [12][13][14][15] Additionally, in the SWIR band, we find the optical absorption peaks of water, collagen, and lipids, three major molecules of human tissues.…”

“…[9][10][11][12] The second window of the NIR (NIR-II) region, also called short-wave infrared region (SWIR, defined here as 1100 to 2000 nm), is of current interest due to the relative low levels of scattering and the high-maximum permissible exposure compared with the NIR-I region. [12][13][14][15] Additionally, in the SWIR band, we find the optical absorption peaks of water, collagen, and lipids, three major molecules of human tissues. [15][16][17] Collagen is an important substance that is the basis of tissues such as the tendons, ligaments, and muscles in our body, and its imaging helps with the diagnosis and monitoring of treatments in a variety of fields, including orthopedics, dermatology, and cardiology.…”

Microporous Organic Polymers: A Synthetic Platform for Engineering Heterogeneous Carbocatalysts

“…However, additional investigation on other reactions such as multiplicative reactions or biological reactions can further characterize catalytic behavior of the materials [46,63] . Also, this conceptual study would advance the design of carbon materials, since microporous polymer networks can be obtained with heteroatoms (e. g., other non‐metals or metalloids) and their physical properties can be widely engineered, which thereby imparts specific activities to carbon materials to form functional additives or imaging agents [64–66] …”

“…[46,63] Also, this conceptual study would advance the design of carbon materials, since microporous polymer networks can be obtained with heteroatoms (e. g., other non-metals or metalloids) and their physical properties can be widely engineered, which thereby imparts specific activities to carbon materials to form functional additives or imaging agents. [64][65][66] Experimental Section Materials Syntheses of porous polymers: 1,3,5-Triethynylbenzene (50 mg, 0.33 mmol, 1.0 equiv. ), 2,5-diiodopyridine (110.16 mg, 0.33 mmol, 1.0 equiv.…”

Synthesis, characterization, and biological applications of semiconducting polythiophene‐based nanoparticles

“…Notably, the absorption of NIR light by PT‐NPs can also generate ultrasonic waves that, if received by acoustic detectors, produce high‐resolution images (mm) of deep tumors (cm) 128 . This makes PT‐NPs intrinsic contrast agents for PAI, that is, an emerging imaging technology with potential for preclinical biomedical research and clinical applications 129–132 …”