Research progress of near-infrared fluorescence probes based on indole heptamethine cyanine dyes in vivo and in vitro

Abstract

Near-infrared (NIR) fluorescence imaging is a noninvasive technique that provides numerous advantages for the realtime in vivo monitoring of biological information in living subjects without the use of ionizing radiation. Near-infrared fluorescent (NIRF) dyes are widely used as fluorescent imaging probes. These fluorescent dyes remarkably decrease the interference caused by the self-absorption of substances and autofluorescence, increase detection selectivity and sensitivity, and reduce damage to the human body. Thus, they are beneficial for bioassays. Indole heptamethine cyanine dyes are widely investigated in the field of near-infrared fluorescence imaging. They are mainly composed of indole heterocyclics, heptamethine chains, and N-substituent side chains. With indole heptamethine cyanine dyes as the parent, introducing reactive groups to the parent compounds or changing their structures can make fluorescent probes have different functions like labeling protein and tumor, detecting intracellular metal cations, which has become the hotspot in the field of fluorescence imaging of biological research. Therefore, this study reviewed the applications of indole heptamethine cyanine fluorescent probes to metal cation detection, pH, molecules, tumor imaging, and protein in vivo. The distribution, imaging results, and metabolism of the probes in vivo and in vitro were described. The biological application trends and existing problems of fluorescent probes were discussed.

Near‐infrared emissive polymer‐coated IR‐820 nanoparticles assisted photothermal therapy for cervical cancer cells

“…For the excitation source, light in the NIR spectral region (760-1100 nm) [15] with low scattering is more attractive than visible light (400-760 nm), as NIR light could penetrate deeply and excite the photothermal agents in the deep-tissue, which could improve the efficiency of the PTT. Also, NIR emission light endows fluorescence imaging [16] with high sensitivity, high contrast and clear observation [17][18][19][20][21]. Hence, NIR light has great potential in the diagnosis and treatment of cancer [22].…”

Emergent Biosensing Technologies Based on Fluorescence Spectroscopy and Surface Plasmon Resonance

“…The reactive oxygen radicals as hydrogen peroxide (H 2 O 2 ), superoxide anion radical (O 2 − ), hydroxyl radical (HO − ), peroxynitrite (ONOO − ), and nitric oxide (NO) play important roles in both physiological and pathological conditions, increasing in some diseases, such as cancer, and inflammation. The in vivo detection is difficult due to a short half-life, but different kinds of sensors have been also reported [212]. Genetically encoded sensors for ROS, in particular for H 2 O 2 (namely HyPer) consist of a circularly permuted yellow fluorescence protein (cpYFP) inserted into the regulatory domain of the Escherichia coli hydrogen peroxide-binding protein (OxyR).…”

Cancer and pH Dynamics: Transcriptional Regulation, Proteostasis, and the Need for New Molecular Tools

“…Work with other synthetic reporters has recently made improvements such that they are more compatible with long time-scale in vivo work. For example, indole heptamethine cyanine dyes represent another class of pH-sensitive dyes that are useful for tumor and tissue measurements due to their near infrared fluorescence properties; however, they suffer from poor stability and dim fluorescence [ 99 ]. Ionic liquids have also recently been developed as pH-sensitive tools compatible with live cell and in vivo imaging [ 100 ].…”