Oxidative stress is closely related to the physiopathology of numerous diseases. Reactive oxygen species (ROS), reactive nitrogen species (RNS), and reactive sulfur species (RSS) are direct participants and important biomarkers of oxidative stress.

Schizophrenia is a common type of serious mental illness with an unclear etiology. Recently, the excessive production of hydrogen sulfide in the brain has been considered to be one of the pathophysiological bases of schizophrenia. However, due to the existence of the blood–brain barrier (BBB), almost no fluorescent probe has been successfully used for the sensing and detection of H2S in the brain. Herein, we designed and synthesized a series of near-infrared fluorescent probes SiR-Bs based on a hemicyanine and Si-rhodamine structure. Among them, Mindo-SiR presented a good penetration ability of the BBB, a high brain uptake (transport: 4.95% ID/g at 5 min), and good response to H2S in vitro and in vivo. For the first time, a fluorescent probe was used to image the changes of H2S in the brains of schizophrenic (SZ) mouse models, and it was successfully proven that there was an abnormally high level of H2S in the brains of SZ mice. Moreover, the therapeutic effect of risperidone for the treatment of SZ could be evaluated by the changes of SiR-Bs’ fluorescence imaging.

The construction of organelle-targeting nanomaterials is an effective way to improve tumor imaging and treatment. Here, a new type of composite nanomaterial named as PTTPB is developed. PTTPB is composed of organelle-targeting aggregation-induced emission photosensitizer TTPB and polydopamine nanomaterials. With the functional modification of TTPB, PTTPB can recognize sialic acid on the cell membrane and present mitochondrial targeted capabilities. The intake of PTTPB in cancerous cells can be increased by the recognition process of cell membrane. PTTPB can generate singlet oxygen for photodynamic therapy (PDT), and present good photothermal conversion ability with irradiation. The PTTPB with organelle-targeting imaging-guided can realize the tumor ablation with the synergistic effect of PDT and photothermal therapy.

Semiconducting polymer has a high extinction coefficient and a long band absorption and can be used as a photoacoustic imaging contrast agent. However, nonbiodegradable semiconducting polymers may cause biosafety issues due to being retained in the body. Therefore, developing degradable semiconducting polymers is necessary for in vivo imaging. Herein, we developed three degradable semiconducting polymers with unique optical properties. We adjusted the optical properties of semiconducting polymers by designing the molecular structure of semiconducting polymers. Polymers with a donor−π−acceptor structure could easily improve the optical properties through adjusting the donor or acceptor units. Through adjusting the electron-donor and -acceptor units, three diketopyrrolopyrrole derivative polymers (DPPTz, DPPQu, and DPPWu) were synthesized and converted into nanosize particles. By introducing the degradable chemical groups in the main chain structure of semiconducting polymers, diketopyrrolopyrrole polymers could be degraded by ClO − . Among these nanosize particles, DPPTz NPs and DPPQu NPs were used to achieve the in vivo photoacoustic imaging of λ-carrageenan-induced arthritis mouse model. This work provides a novel design idea for the designing of red-shifted semiconducting polymer with degradable properties.

Various functional chemical materials have been widely used in imaging and tumor therapy. Targeted ligands such as antibodies, peptides, and small molecules have been combined with functional materials to enhance cellular uptake and are used for active targeting of cancer cells and tumors. Among them, phenylboronic acid (PBA), as a small molecular ligand, has the characteristics of low cytotoxicity and easy modification. PBA improves the cancer cell imaging and tumor treatment effect by binding to glycans on the surface of cancer cells. In this Mini-Review, we introduced the modification strategy and targeting strategy of PBA. We focused on the applications of PBA-based functional materials in fluorescence imaging and tumor therapy. For fluorescence imaging, the potential of PBA-based functional chemical materials in cancer diagnosis and tumor targeting was proved by cell imaging and in vivo imaging. For tumor therapy, we mainly discussed the applications of PBA-based functional chemical materials in chemotherapy, gene therapy, phototherapy, and immunotherapy. PBA-based functional chemical materials provide a useful method for cancer diagnosis and treatment.