Recent advances of smart AIEgens for photoacoustic imaging and phototherapy

Recent advances in near-infrared organic photosensitizers for photodynamic cancer therapy

With the advancement of photodynamic therapy, various photosensitizers have been developed to enhance the efficacy of cancer treatment while minimizing side effects. Recently, near-infrared organic fluorophores have gained significant attention as promising photodynamic agents for cancer therapy due to their tunable photophysical properties, structural versatility, good biocompatibility, high biosafety, and synthetic flexibility. In particular, near-infrared organic photosensitizers offer several notable advantages, including deep tissue penetration, a low fluorescence background for bioimaging, and reduced damage to biological tissues compared to traditional visible-spectrum photosensitizers. In this minireview, we will discuss the current developments in near-infrared organic photosensitizers for photodynamic cancer therapy. Furthermore, we will briefly highlight the challenges and prospects in this field. This minireview aims to encourage more researchers to develop advanced near-infrared organic photosensitizers and facilitate their transition from laboratory research to preclinical studies and ultimately to clinical use.

Inflammation-reducing thermosensitive hydrogel with photothermal conversion for skin cancer therapy

Photothermal therapy (PTT) has widely been utilized for postoperative treatment of skin cancer, while high temperature, usually >50 °C, would induce damage to healthy tissue and increased wound inflammation. Herein, we developed an "all in one" hydrogel to enhance mild PTT for postoperative skin cancer treatment while circumventing photothermo-induced inflammation by loading quercetin (Que)-coated tannin‑iron (TA-Fe) nanoparticles with poly (N-acrylylglycine) amine (PNAGA) hydrogel (Que@TA-Fe@PNAGA). Exposure to near-infrared light, Que.@TA-Fe@PNAGA occurred a mild temperature increase (∼47 °C), which induces local mild PTT and disrupts the hydrogen bonds within the hydrogel, triggering a gel-to-sol phase transition and the release of Que.@TA-Fe nanoparticles. These released nanoparticles inhibit the expression of heat shock proteins in tumor cells by producing reactive oxygen species and enter inflammatory cells to release TA and Que. via acid hydrolysis, reducing tumor necrosis factor-α expression by 66.6 % and promoting M1-to-M2 macrophage conversion. Based on this integrated functionality, Que.@TA-Fe@PNAGA hydrogel achieves over 99.4 % tumor inhibition rate, effectively avoids photothermo-induced damage in normal tissue and inflammation, and thus represents a new approach for postoperative photothermal therapy in skin cancer treatment.

Stepwise Lighting Up Gold(I)-Thiolate Complexes from AIE Nanoaggregates to AIEE Nanoprobes with a ZIF-8 Shell for Glucose Biosensing

Aggregation-induced emission (AIE) or aggregation-induced emission enhancement (AIEE) has endowed gold species with responsive fluorescent properties, favoring their potential applications in sensing, imaging, and therapy. However, it remains an interesting challenge to fabricate fluorophores with both AIE and AIEE effects. Herein, we presented highly luminescent Au(I) thiolate nanocomplex-based biosensors with Zn2+ induced-AIE and zeolite imidazolate framework (ZIF-8) induced-AIEE effects. The nonemissive monovalent gold-glutathione complexes (AuI-SGs) were obtained to synthesize the core-shell Zn2+/AuI-SG@ZIF-8 composites with strong luminescence via the coordination-assisted self-assembly strategy. By immobilizing GOx on the surface of Zn2+/AuI-SG@ZIF-8, Zn2+/AuI-SG@ZIF-8/GOx biosensors exhibited effective responsiveness to glucose, showing a "turn-off" detection model. The mechanism study revealed that the robust luminescence of Zn2+/AuI-SG@ZIF-8 to glucose sensing was attributed to the acid-stimulated degradation of the probe facilitated by H+ generated from the glucose oxidase (GOx)-catalyzed oxidation process. To achieve noninvasive and intelligent blood glucose detection, the Zn2+/AuI-SG@ZIF-8/GOx-loaded microneedle (MN)-patch fluorescent platform was further developed. The MN-patch-based sensing platform had promising performance for on-needle capture and in situ glucose detection. This study demonstrated a universal and feasible protocol to construct luminescent biosensors for glucose detection and their potential for the development of MN-based analytical devices.

Advances in biomimetic AIE nanoparticles for diagnosis and phototherapy

This minireview provides an overview of the recent advancements in the development of biomimetic Aggregation-Induced Emission (AIE) nanoparticles and their applications in disease diagnosis, phototherapy, and photoimmunotherapy. AIE nanoparticles can be engineered to enable efficient image-guided photodynamic and photothermal therapies, however, challenges related to immune defense and target specificity persist. To overcome these, coating biomimetic materials on the surface of AIE nanoparticles, which mimic the features and functions of native cells, have emerged as a promising solution. This minireview will highlight the synthesis strategies and discuss the biomedical application of biomimetic AIE nanoparticles.

A novel pH-activated AIEgen probe for dynamic lysosome tracking and high-efficiency photodynamic therapy

A novel AIEgen molecular probe (N-3QL) with typical AIE effects, good biocompatibility, lysosome targeting, pH activation, excellent photostability, and high brightness was synthesized using two simple synthetic steps. Spectroscopic and cytotoxicity experiments indicate that N-3QL can not only be used for the dynamic monitoring of cancer cell lysosomes, but also for photodynamic therapy (PDT) ablation of cancer cells.

Recent advances in DNA-based probes for photoacoustic imaging

Photoacoustic imaging(PAI) is a widely developing imaging modality that has seen tremendous evolvement in the last decade. PAI has gained the upper hand in the imaging field as it takes advantage of optical absorption and ultrasound detection that imparts higher resolution, rich contrast and elevated penetration depth. Unlike other imaging techniques, PAI does not use ionising radiation and is a better, cost-effective and healthier alternative to other imaging techniques. It offers greater specificity than conventional ultrasound imaging with the ability to detect haemoglobin, lipids, water and other light-absorbing chromophores. These properties of PAI have led to its extended applications in the biomedical field in the treatment of diseases such as cancer. This paper reviews how DNA probes have been used in PAI, the various techniques by which it has been modified, and their role in the process. We also focus on different nanocomposites containing DNA having PAI and photothermal therapy(PTT) properties for detection, diagnosis and therapy, its constituents and the role of DNA in it.

Photostable and high-brightness aggregation-induced emission of iridium luminogen achieving reliable and sensitive continuous luminescent quantification of molecular oxygen

Online continuous luminescent oxygen quantification requires both high-brightness luminescence and superior photobleaching resistance of luminogens to afford the requisite level of sensitivity and operational stability, which remains a challenge. Herein, a fluorine-free design strategy of incremental rotors for preparing iridium luminogens with excellent photobleaching resistance and high-brightness aggregation-induced emission (AIE) is presented. The incremental rotors gradually improve the rotational activity of substituents, efficaciously activating the AIE with synchronously improved aggregation-state luminescence efficiency, which is theoretically confirmed by the variations of dipole moments and experimentally verified by the luminescent lifetimes. Moreover, the introduction of triphenylamine significantly improves the photobleaching resistance of iridium luminogens. Subsequently, by optimizing the loading capacity of the iridium luminogen, the improvement of high-brightness AIE on the oxygen sensitivity of ethocel films is successfully observed. Thickness attenuation of ethocel films dramatically shortens the quenching/recovery response to 4.7 s. Importantly, owing to the exceptional photobleaching resistance of the iridium luminogen, distinguished photo-fatigue resistance with operational stability is exhibited by the ethocel film with no luminescence attenuation during 8000 s continuous oxygen quantification.

Self-Assembly Induced Photosensitization of Long-Tailed Heavy-Atom-Free BODIPY Derivatives for Photodynamic Therapy

Type I photosensitizers (PSs) are a promising approach for photodynamic therapy (PDT) since they can generate radicals that are tolerant to hypoxia. Thus, the development of highly efficient type I PSs is essential. Self-assembly is a promising strategy for developing novel PSs with desirable properties. Here, a simple and effective approach is developed to create heavy-atom-free PSs for PDT by self-assembling long-tailed boron dipyrromethene dyes (BODIPYs). The resulting aggregates BY-I16 and BY-I18 can efficiently convert their excited energy to the triplet state, producing reactive oxygen species that are essential for PDT. Furthermore, the aggregation and PDT performance can be regulated by adjusting the length of the tailed alkyl chains. As proof of concept, the efficacy of these heavy-atom-free PSs both in vitro and in vivo under both normoxic and hypoxic conditions is demonstrated.

Recent Progress of Preparation Strategies in Organic Nanoparticles for Cancer Phototherapeutics

Phototherapy has the advantages of being a highly targeted, less toxic, less invasive, and repeatable treatment, compared with conventional treatment methods such as surgery, chemotherapy, and radiotherapy. The preparation strategies are significant in order to determine the physical and chemical properties of nanoparticles. However, choosing appropriate preparation strategies to meet applications is still challenging. This review summarizes the recent progress of preparation strategies in organic nanoparticles, mainly focusing on the principles, methods, and advantages of nanopreparation strategies. In addition, typical examples of cancer phototherapeutics are introduced in detail to inform the choice of appropriate preparation strategies. The relative future trend and outlook are preliminarily proposed.

Vascular disruption agent and phototherapeutic assembled nanoparticles for enhanced tumor inhibition

Vascular disruption agent (combretastatin A-4 phosphate) and phototherapeutic (IEICO-4F) assembled nanoparticles (IFC NPs) were prepared for the first time. The IFC NPs have a high photo energy utilization efficiency of up to 96.1%, and could significantly inhibit tumor growth by photodynamic and photothermal therapy enhanced tumor vascular disruption.

"Trojan Horse" Phototheranostics: Fine-Engineering NIR-II AIEgen Camouflaged by Cancer Cell Membrane for Homologous-Targeting Multimodal Imaging-Guided Phototherapy

Multimodal phototheranostics on the basis of a single molecule with one-for-all characteristics represents a convenient approach for effective cancer treatment. In this report, a versatile molecule featured by aggregation-induced emission, namely DHTDP, synchronously enabling second near-infrared (NIR-II) fluorescence emission and efficient photothermal conversion is developed by elaborate structural modulation. By camouflaging DHTDP nanoparticles with cancer cell membrane, the resultant biomimetic nanoparticles exhibit significantly both facilitated delivery efficiency and homologous targeting capability, and afford precise imaging guidance and maximize therapeutic outcomes in form of NIR-II fluorescence imaging (FLI)-photoacoustic imaging (PAI)-photothermal imaging (PTI) trimodal imaging-guided photothermal therapy (PTT). This study presents the first example of biomimetic multimodal phototheranostics loaded by homogeneity-targeting cell membrane, thus brings a new insight into the exploration of superior phototheranostics for practical cancer theranostics.

Recent development of photoacoustic imaging in dentistry: A review on studies over the last decade

Background

This work performs a literature review of photoacoustic imaging (PAI) in dentistry and discusses the development of PAI in relation to oral health.

Methods

A search method was used to locate papers published between 2011 and 2023 in Google Scholar and PubMed databases, and 25 studies were selected. Reports on PAI in dentistry were included. Articles not written in English or whose full text could not be accessed were excluded. The remaining publications were checked and evaluated to determine whether they contain supportive materials for PAI in dentistry.

Results

The majority of articles about PAI in dentistry are associated with caries studies. Photoacoustic microscopy is the most commonly utilized PAI system. PAI studies generally focus on ex-vivo investigations using extracted human teeth. The acoustic signal obtained from carious teeth is greater than that obtained from normal teeth. In addition to imaging oral soft tissues from animal models and the periodontal pocket depth in human volunteers, PAI is applied to evaluate dental implants and oral biofilms.

Conclusion

There have been numerous investigation on PAI in dentistry, but it is not yet applicable in dental practice. In the future, PAI studies are expected to contribute to the invention of an alternative non-ionizing imaging technology that is comfortable for patients, user friendly, and capable of providing reliable information at a reasonable cost.

Near-infrared metal agents assisting precision medicine: from strategic design to bioimaging and therapeutic applications

Metal agents have made incredible strides in preclinical research and clinical applications in recent years, but their short emission/absorption wavelengths continue to be a barrier to their distribution, therapeutic action, visual tracking, and efficacy evaluation. Nowadays, the near-infrared window (NIR, 650-1700 nm) provides a more accurate imaging and treatment option. Thus, there has been ongoing research focusing on developing multifunctional NIR metal agents for imaging and therapy that have deeper tissue penetration. The design, characteristics, bioimaging, and therapy of NIR metal agents are covered in this overview of papers and reports published to date. To start with, we focus on describing the structure, design strategies, and photophysical properties of metal agents from the NIR-I (650-1000 nm) to NIR-II (1000-1700 nm) region, in order of molecular metal complexes (MMCs), metal-organic complexes (MOCs), and metal-organic frameworks (MOFs). Next, the biomedical applications brought by these superior photophysical and chemical properties for more accurate imaging and therapy are discussed. Finally, we explore the challenges and prospects of each type of NIR metal agent for future biomedical research and clinical translation.

Recent progress in metal complexes functionalized nanomaterials for photodynamic therapy

Metal complexes have shown promise as photosensitizers for cancer diagnosis and therapeutics. However, the vast majority of metal photosensitizers are not ideal and associated with several limitations including pharmacokinetic limitations, off-target toxicity, fast systemic clearance, poor membrane permeability, and hypoxic tumour microenvironments. Metal complex functionalized nanomaterials have the potential to construct multifunctional systems, which not only overcome the above defects of metal complexes but are also conducive to modulating the tumour microenvironment (TME) and employing combination therapies to boost photodynamic therapy (PDT) efficacy. In this review, we first introduce the current challenges of photodynamic therapy and summarize the recent research strategies (such as metal coordination bonds, self-assembly, π-π stacking, physisorption, and so on) used for preparing metal complexes functionalized nanomaterials in the application of PDT.

Recent Organic Photosensitizer Designs for Evoking Proinflammatory Regulated Cell Death in Antitumor Immunotherapy

In the past decades, immunotherapy has achieved a series of clinical successes in the field of cancer. However, existing therapeutic options usually show a low immune response to solid tumors caused by immunosuppressive "cold" tumor microenvironment (TME). Several types of proinflammatory regulated cell death (RCD), mainly including ferroptosis and pyroptosis, have been studied recently, which can provide proinflammatory signals and immunogenicity necessary for remodeling TME and activating an antitumor immune response. A variety of chemotherapeutic drugs are proven to be effective in the proinflammatory RCD induction of tumor cells, but several adverse effects and intrinsic drug resistance usually occur in the therapeutic process, greatly hindering their further clinical application. The emerging organic photosensitizer (PS)-based materials open new possibilities to effectively activate proinflammatory RCD through precise spatiotemporal regulation of intracellular reactive oxygen species-associated signaling pathways, which can overcome many challenges encountered in current proinflammatory RCD-mediated immunotherapy. In this review, the recent design strategies of PS probes are detailly summarized and their potential advantages for tumor-specific proinflammatory RCD induction are discussed. Moreover, the representative examples in cancer immunotherapy are highlighted and future perspectives in this emerging field are proposed.