Polymer‐based activatable optical probes for tumor fluorescence and photoacoustic imaging

Engineering Nanoplatforms for Theranostics of Atherosclerotic Plaques

Atherosclerotic plaque formation is considered the primary pathological mechanism underlying atherosclerotic cardiovascular diseases, leading to severe cardiovascular events such as stroke, acute coronary syndromes, and even sudden cardiac death. Early detection and timely intervention of plaques are challenging due to the lack of typical symptoms in the initial stages. Therefore, precise early detection and intervention play a crucial role in risk stratification of atherosclerotic plaques and achieving favorable post-interventional outcomes. The continuously advancing nanoplatforms have demonstrated numerous advantages including high signal-to-noise ratio, enhanced bioavailability, and specific targeting capabilities for imaging agents and therapeutic drugs, enabling effective visualization and management of atherosclerotic plaques. Motivated by these superior properties, various noninvasive imaging modalities for early recognition of plaques in the preliminary stage of atherosclerosis are comprehensively summarized. Additionally, several therapeutic strategies are proposed to enhance the efficacy of treating atherosclerotic plaques. Finally, existing challenges and promising prospects for accelerating clinical translation of nanoplatform-based molecular imaging and therapy for atherosclerotic plaques are discussed. In conclusion, this review provides an insightful perspective on the diagnosis and therapy of atherosclerotic plaques.

Activatable Probes for Ratiometric Imaging of Endogenous Biomarkers In Vivo

Dynamic variations in the concentration and abnormal distribution of endogenous biomarkers are strongly associated with multiple physiological and pathological states. Therefore, it is crucial to design imaging systems capable of real-time detection of dynamic changes in biomarkers for the accurate diagnosis and effective treatment of diseases. Recently, ratiometric imaging has emerged as a widely used technique for sensing and imaging of biomarkers due to its advantage of circumventing the limitations inherent to conventional intensity-dependent signal readout methods while also providing built-in self-calibration for signal correction. Here, the recent progress of ratiometric probes and their applications in sensing and imaging of biomarkers are outlined. Ratiometric probes are classified according to their imaging mechanisms, and ratiometric photoacoustic imaging, ratiometric optical imaging including photoluminescence imaging and self-luminescence imaging, ratiometric magnetic resonance imaging, and dual-modal ratiometric imaging are discussed. The applications of ratiometric probes in the sensing and imaging of biomarkers such as pH, reactive oxygen species (ROS), reactive nitrogen species (RNS), glutathione (GSH), gas molecules, enzymes, metal ions, and hypoxia are discussed in detail. Additionally, this Review presents an overview of challenges faced in this field along with future research directions.

Smart Biomimetic Nanozymes for Precise Molecular Imaging: Application and Challenges

New nanotechnologies for imaging molecules are widely being applied to visualize the expression of specific molecules (e.g., ions, biomarkers) for disease diagnosis. Among various nanoplatforms, nanozymes, which exhibit enzyme-like catalytic activities in vivo, have gained tremendously increasing attention in molecular imaging due to their unique properties such as diverse enzyme-mimicking activities, excellent biocompatibility, ease of surface tenability, and low cost. In addition, by integrating different nanoparticles with superparamagnetic, photoacoustic, fluorescence, and photothermal properties, the nanoenzymes are able to increase the imaging sensitivity and accuracy for better understanding the complexity and the biological process of disease. Moreover, these functions encourage the utilization of nanozymes as therapeutic agents to assist in treatment. In this review, we focus on the applications of nanozymes in molecular imaging and discuss the use of peroxidase (POD), oxidase (OXD), catalase (CAT), and superoxide dismutase (SOD) with different imaging modalities. Further, the applications of nanozymes for cancer treatment, bacterial infection, and inflammation image-guided therapy are discussed. Overall, this review aims to provide a complete reference for research in the interdisciplinary fields of nanotechnology and molecular imaging to promote the advancement and clinical translation of novel biomimetic nanozymes.

Polymeric agents for activatable fluorescence, self-luminescence and photoacoustic imaging

Numerous polymeric agents have been widely applied in biology and medicine by virtue of the facile chemical modification, feasible nano-engineering approaches and fine-tuned pharmacokinetics. To endow polymeric imaging agents with ability to monitor and measure subtle molecular or cellular alterations at diseased sites, activatable polymeric probes that can elicit signal changes in response to biomolecular interactions or the analytes of interest have to be developed. Herein, this review aims to provide a systemic interpretation and summarization of the design methodology and imaging utility of recently emerged activatable polymeric probes. An introduction of activatable probes allowing for precise imaging and classification of polymeric imaging agents is reported first. Then, we give a detailed discussion of the contemporary design approaches toward activatable polymeric probes in diverse imaging modes for the detection of various stimuli and their imaging applications. Finally, current challenges and future advances are discussed and highlighted.

Biomedical polymers: synthesis, properties, and applications

Biomedical polymers have been extensively developed for promising applications in a lot of biomedical fields, such as therapeutic medicine delivery, disease detection and diagnosis, biosensing, regenerative medicine, and disease treatment. In this review, we summarize the most recent advances in the synthesis and application of biomedical polymers, and discuss the comprehensive understanding of their property-function relationship for corresponding biomedical applications. In particular, a few burgeoning bioactive polymers, such as peptide/biomembrane/microorganism/cell-based biomedical polymers, are also introduced and highlighted as the emerging biomaterials for cancer precision therapy. Furthermore, the foreseeable challenges and outlook of the development of more efficient, healthier and safer biomedical polymers are discussed. We wish this systemic and comprehensive review on highlighting frontier progress of biomedical polymers could inspire and promote new breakthrough in fundamental research and clinical translation.

A bioactivated in vivo assembly nanotechnology fabricated NIR probe for small pancreatic tumor intraoperative imaging

Real-time imaging of the tumour boundary is important during surgery to ensure that sufficient tumour tissue has been removed. However, the current fluorescence probes for bioimaging suffer from poor tumour specificity and narrow application of the imaging window used. Here, we report a bioactivated in vivo assembly (BIVA) nanotechnology, demonstrating a general optical probe with enhanced tumour accumulation and prolonged imaging window. The BIVA probe exhibits active targeting and assembly induced retention effect, which improves selectivity to tumours. The surface specific nanofiber assembly on the tumour surface increases the accumulation of probe at the boundary of the tumor. The blood circulation time of the BIVA probe is prolonged by 110 min compared to idocyanine green. The assembly induced metabolic stability broaden the difference between the tumor and background, obtaining a delayed imaging window between 8-96 h with better signal-to-background contrast (>9 folds). The fabricated BIVA probe permits precise imaging of small sized (<2 mm) orthotopic pancreatic tumors in vivo. The high specificity and sensitivity of the BIVA probe may further benefit the intraoperative imaging in a clinical setting.

Intelligent Tumor Microenvironment-Activated Multifunctional Nanoplatform Coupled with Turn-on and Always-on Fluorescence Probes for Imaging-Guided Cancer Treatment

Intrinsic tumor microenvironment (TME)-related therapeutic resistance and nontumor-specific imaging have limited the application of imaging-guided cancer therapy. Herein, a TME-responsive MnO₂-based nanoplatform coupled with turn-on and always-on fluorescence probes was designed through a facile biomineralization method for imaging-guided photodynamic/chemodynamic/photothermal therapy (PDT/CDT/PTT). After the tumor-targeting delivery of the AuNCs@MnO₂-ICG@AS1411 (AMIT) nanoplatform via aptamer AS1411, the TME-responsive dissociation of MnO₂ generated sufficient O₂ and Mn²⁺ with the consumption of GSH for improving PDT efficacy and Fenton-like reaction-mediated CDT. Simultaneously, the released small-sized ICG and AuNCs facilitated PDT and PTT efficacy via the deep tumor penetration. Moreover, the turn-on fluorescence of AuNCs revealed the real-time TME-responsive MnO₂ degradation process, and the always-on ICG fluorescence enabled the in situ monitoring of the payload distribution in vitro and in vivo. The AMIT NPs also provided magnetic resonance and thermal imaging guidance for the enhanced PDT, CDT, and PTT. Therefore, this all-in-one nanosystem provides a simple and versatile strategy for multiple imaging-guided theranostic applications.

Hemicyanine-Based Near-Infrared Activatable Probes for Imaging and Diagnosis of Diseases

Molecular activatable probes with near-infrared (NIR) fluorescence play a critical role in in vivo imaging of biomarkers for drug screening and disease diagnosis. With structural diversity and high fluorescence quantum yields, hemicyanine dyes have emerged as a versatile scaffold for the construction of activatable optical probes. This Review presents a survey of hemicyanine-based NIR activatable probes (HNAPs) for in vivo imaging and early diagnosis of diseases. The molecular design principles of HNAPs towards activatable optical signaling against various biomarkers are discussed with a focus on their broad applications in the detection of diseases including inflammation, acute organ failure, skin diseases, intestinal diseases, and cancer. This progress not only proves the unique value of HNAPs in preclinical research but also highlights their high translational potential in clinical diagnosis.

Achievement in active agent structures as a power tools in tumor angiogenesis imaging

According to World Health Organization (WHO) cancer is the second most important cause of death globally. Because angiogenesis is considered as an essential process of growth, proliferation and tumor progression, within this review we decided to shade light on recent development of chemical compounds which play a significant role in its imaging and monitoring. Indeed, the review gives insight about the current achievements of active agents structures involved in imaging techniques such as: positron emission computed tomography (PET), magnetic resonance imaging (MRI) and single photon emission computed tomography (SPECT), as well as combination PET/MRI and PET/CT. The review aims to provide the journal audience with a comprehensive and in-deep understanding of chemistry policy in tumor angiogenesis imaging.