Near-infrared Cyanine Dye Photoacoustic Probe And Its Application In Animal And Plant Detection

Photoacoustic imaging?PAI?combined with the high specificity of optical imaging and the deep penetration characteristics of ultrasound imaging has become an emerging structural and functional imaging technology in the biomedical field.PAI utilizes ultrasound signals as an information carrier to capture information about the physiology and pathology associated with optical absorption characteristics within the tissue.The basic process is summarized as follows:?1?tissue absorbs light energy from visible or near-infrared light;?2?adiabatic expansion of contrast agent produces photoacoustic signal;?3?sensor receive the signal;?4?The data is storage by photoacoustic system and used for analysis and construction of images.Since the scattering of sound in biological tissue is less than light,PAI can provide higher resolution imaging at depths that are not possible with pure optical methods,effectively overcoming the limitations of optical imaging in terms of penetration depth.Today,PAI-based detection methods have been widely used for the detection of specific analytes in vivo,such as the internal environment?biomolecules and metal ions.However,the development of high sensitivity and high selectivity photoacoustic probes remains a major challenge for photoacoustic detection.Near-infrared absorbing organic dyes,such as cyanine dyes,polyethylene diimine derivatives,and semiconducting polymers,have good biodegradability and biocompatibility,can be made into the stable photoacoustic probe with good selectivity by rational design modification and further used for the detection of specific analytes in animals and plants or the monitoring of secretion status.Based on organic cyanine dyes,this master's thesis designed and prepared two organic near-infrared photoacoustic probes for the detection of analytes in animals and plants under guidance of PAI.The main research contents are as follows:1.Near-infrared organic cyanine dye photoacoustic probe for detection of copper ions(Cu²⁺)in plants and animals:preparation of novel heptamethine cyanine dye?IR823?by Kevangeloid condensation reaction,and ligand dipyridylamine?metal ion chelate The mixture?reacts to synthesize an activatable photoacoustic probe LET-2.When the present of Cu²⁺,LET-2 chelate with Cu2+,resulting in absorption red shift and photoacoustic signal enhancement,thereby achieving the photoacoustic detection of Cu²⁺.LET-2 has a significant photoacoustic opening effect on low concentrations of Cu²⁺and has good selectivity for potentially competitive analytes.In vitro calculation of LET-2 has a very low detection limit for photoacoustic detection of Cu²⁺?about 10.8×10-9 M?.Finally,we successfully monitored Cu²⁺in bean sprouts and mouse liver tissue by photoacoustic imaging.The results show that the designed chemoselective Cu²⁺photoacoustic probe has great potential in environmental monitoring and disease diagnosis.2.Near-infrared organic cyanine dye photoacoustic nanoprobe for monitoring and evaluation of gastric acid secretion in mice:synthesizing acid-responsive small organic molecules with cyanine dye?IR1061?and ligand 3-butene-1-amine.After modificated by amphoteric copolymerization DSPE-PEG2000,the nanomaterial LET-4 with good biocompatibility is obtained.Under acidic conditions,the absorption of LET-4 in the near-infrared region is significantly enhanced and produces a distinct photoacoustic signal.Through PAI,we successfully observed the process of gastric acid secretion?gastric emptying,gastric acid secretion,and probe metabolism?in mice after intragastric administration.Through 3D modeling,we successfully constructed 3D PAI of gastric acid secretion,which effectively reduced signal interference from background and other tissues,and finally realized the monitoring and evaluation of gastric acid status under the guidance of 3D PAI.In this master's thesis,we designed and synthesized two photoacoustic probes with organic cyanine dye as the main structure,and used it for Cu²⁺detection and gastric acid status monitoring under the guidance of PAI.The results of this study have potential applications in the design of photoacoustic probes on organic cyanine dyes and their applications in biomedical applications.