Multimodal probes for the detection of bone cancer-related disease in biological systems: Recent advances and future prospects

Bone cancer can be broadly categorized into primary bone cancer and metastatic bone cancer. Primary bone cancer, such as osteosarcoma and Ewing's sarcoma, is not only highly malignant but also tends to occur in younger age groups. Metastatic bone cancer typically originates from highly malignant diseases like prostate cancer, breast cancer, and lung cancer. The presence of bone metastasis usually indicates a poor prognosis. Therefore, early detection and treatment of bone lesions are crucial for improving patient prognosis and quality of life. Commonly used conventional detection methods, such as bone imaging, computed tomography (CT), and magnetic resonance imaging (MRI), suffer from limitations in resolution or penetration depth. As a result, the detection rate for small early bone metastases is often poor. Positron emission tomography (PET) and single-photon emission computed tomography (SPECT) utilize radionuclide-labeled imaging agents to perform functional imaging. These techniques improve the specificity of detection and provide information about tissue metabolism based on the concentration of different components in various tissues. However, PET and SPECT are susceptible to interference from factors like infection and necrosis, which may lead to false-positive results. Chemical probes have largely compensated for the lack of specificity and sensitivity of conventional methods, especially Near-Infrared (NIR) and photoacoustic (PA) imaging, which not only increase the depth of detection but also do not have radiological hazards. In this review, we will discuss the importance of probes for the early detection of bone-associated cancers. Specifically, we will examine probe-associated markers, recognition modalities, and imaging modalities in the context of probes used for metastatic bone cancers originating from breast and prostate cancers, as well as for primary osteosarcoma. The use of targeted probes enables the identification of cancerous lesions in bone through binding to biomarkers expressed in cancer cells. Different probe designs allow for various recognition strategies and imaging techniques to visualize the probes after they have bound to cancer cells. Understanding current probe technologies is critical for improving early diagnosis and treatment of bone cancers.