Acceptor engineering of metallacycles with high phototoxicity indices for safe and effective photodynamic therapy

Dinuclear Dicationic Iridium Complexes for Highly Synergistic Photodynamic and Photothermal Therapy to Chemoresistant Cancer

A series of dinuclear Ir(III) complexes have been constructed for enhanced photodynamic and photothermal therapy (PDT and PTT) for cisplatin-resistant non-small-cell lung cancer. They enter cells via caveolar endocytosis, target mitochondria but not nuclear, generate both singlet oxygen and superoxide anion, and release heat when exposed to infrared (IR) irradiation, thus inducing reactive oxygen species (ROS)-associated cell disruption and thermal ablation. The IR-generated ROS can further activate caspases, triggering apoptosis. Additionally, the ROS deplete intracellular glutathione, lead to lipid peroxidation, and induce ferroptosis. The selected dinuclear Ir(III) complex Ir4 can completely eradicate cisplatin-resistant non-small-cell lung tumor in 75% of the phototreated mice with an inhibition rate of tumor growth above 96%. They have an extremely low toxicity to normal liver and kidney cells. After therapy, metal was not detected in the collected organs of mice except the tumor. A synergistic therapy consisting of potent IR-driven PDT and mild PTT accomplished by single-molecule dinuclear Ir(III) complexes is highly significant for the safe and effective PDT of large, deep-seated tumors as well as for overcoming the complicated drug resistance mechanisms of cancer.

Design of an anti-PD-L1-mediated MOF nanodrug delivery system using terpyridine-metal coordination for tumor theranostics

An anti-PD-L1 mediated nanodrug delivery system is developed by modifying the MOF surface and using Tpy-Gd3+-Tpy coordination chemistry, enabling the simultaneous delivery of chemotherapy and immunotherapy drugs. The platform enables regulated drug release and integrates multiple imaging modalities, promoting targeted delivery and facilitating tumor diagnosis through FL and MR imaging.

An Ultrasound-Activated Supramolecular Modulator Enhancing Autophagy to Prevent Ventricular Arrhythmias Post-Myocardial Infarction

Ventricular arrhythmias (VAs) triggered by myocardial infarction (MI) are the leading cause of sudden cardiac mortality worldwide. Current therapeutic strategies for managing MI-induced VAs, such as left stellate ganglion resection and ablation, are suboptimal, highlighting the need to explore safer and more effective intervention strategies. Herein, we rationally designed two supramolecular sonosensitizers RuA and RuB, engineered through acceptor modification to generate moderate reactive oxygen species (ROS) to modulate VAs. Both RuA and RuB demonstrated high ultrasound (US)-activated ROS production efficiency, with singlet oxygen (1O2) quantum yield (ΦΔ) of 0.70 and 0.88, respectively, surpassing ligand IR1105 and the conventional sonosensitizer ICG (ΦΔ=0.40). In vitro, RuB, at a modest concentration and under US intensity notably boosts pro-survival autophagy in microglia BV2 cell. To improve in vivo stability and biocompatibility, RuB was further encapsulated into DSPE-PEG5000 to prepare RuB nanoparticles (RuB NPs). In vivo studies after microinjection of RuB NPs into the paraventricular nucleus (PVN) and subsequent US exposure, demonstrated that RuB NPs-mediated US modulation effectively suppresses sympathetic nervous activity (SNA) and inflammatory responses, thereby preventing VAs. Importantly, no tissue injury was observed post RuB NPs-mediated US modulation. This work pioneers the design of long-wave emission supramolecular sonosensitizers, offering new insights into regulating cardiovascular diseases.

Molecular Engineering of Xanthene Dyes with 3D Multimodal-Imaging Ability to Guide Photothermal Therapy

Phototheranostics integrates light-based diagnostic techniques with therapeutic interventions, offering a non-invasive, precise, and swift approach for both disease detection and treatment. The efficacy of this approach hinges on the multimodal imaging potential and photothermal conversion efficiency (PCE) of phototheranostic agents (PTAs). Despite the promise, crafting multifunctional phototheranostic organic small molecules brims with challenges. In this research, four innovative xanthene-derived PTAs are synthesized by fine-tuning the donor-π-acceptor (D-π-A) system to strike a balance between radiative and nonradiative decay. The inherent robust photostability and intense fluorescence of the traditional xanthene core are preserved, meanwhile the addition of highly electron-withdrawing groups boosts the non-radiative decay rate to enhance PCE and photoacoustic imaging capabilities. Remarkably, one of the PTAs, DMBA, demonstrates an exceptional absolute fluorescence quantum yield of 2.46% in PBS, and when encapsulated into nanoparticles, it achieves a high PCE of 79.5%. Consequently, DMBA nanoparticles (DMBA-NPs) are effectively employed in fluorescence, 3D photoacoustic, and photothermal imaging-guiding tumor photothermal therapy. This represents the first instance of a multimodal phototheranostic xanthene agent achieving synergistic fluorescence and photoacoustic imaging for diagnostic purposes. Furthermore, this work paves the way for leveraging xanthene fluorophores as versatile tools in the development of multifunctional reagents.

Engineering Stimuli-Responsive Materials for Precision Medicine

Over the past decade, precision medicine has garnered increasing attention, making significant strides in discovering new therapeutic drugs and mechanisms, resulting in notable achievements in symptom alleviation, pain reduction, and extended survival rates. However, the limited target specificity of primary drugs and inter-individual differences have often necessitated high-dosage strategies, leading to challenges such as restricted deep tissue penetration rates and systemic side effects. Material science advancements present a promising avenue for these issues. By leveraging the distinct internal features of diseased regions and the application of specific external stimuli, responsive materials can be tailored to achieve targeted delivery, controllable release, and specific biochemical reactions. This review aims to highlight the latest advancements in stimuli-responsive materials and their potential in precision medicine. Initially, we introduce disease-related internal stimuli and capable external stimuli, elucidating the reaction principles of responsive functional groups. Subsequently, we provide a detailed analysis of representative pre-clinical achievements of stimuli responsive materials across various clinical applications, including enhancements in the treatment of cancers, injury diseases, inflammatory diseases, infection diseases, and high-throughput microfluidic biosensors. Finally, we discuss some clinical challenges, such as off-target effects, long-term impacts of nano-materials, potential ethical concerns, and offer insights into future perspectives of stimuli-responsive materials.

pH-Activatable Molecular Probe for COX-2 Imaging in Human Oral Squamous Carcinoma Cells and Patient-Derived Tissues

For developing a successful cancer therapeutic modality, the early precise detection of cancer cells in patient biopsies in oral squamous cell carcinoma (OSCC) is crucial. This could help researchers create new diagnostic and therapeutic tools and assist clinicians in recommending more effective treatment plans and improving patient survival. We have developed an SMPD, cyclooxygenase-2 (COX-2) targeting pH-activable fluorophore named CNP, combining a potent COX-2 inhibitor, celecoxib, linked to a naphthalimide fluorophore with an acidic microenvironment-responsive piperazine moiety for specific optical imaging of OSCC in cells and patient tissues. Compared to reference probe RNP lacking celecoxib, CNP selectively enters the COX-2 overexpressing oral cancer cells. Its acidity-responsive imaging response enhances selectivity over cancers with lower COX-2 expression levels and normal cells. Further, CNP is demonstrated in imaging OSCC cells in patient-derived biopsies. Thus, multifunctional CNP shows potential in exploring more reagents for fluorescence-based detection of OSCC cells in patient tissues with translational applications.

Targeted Delivery and ROS-Responsive Release of Lutein Nanoassemblies Inhibit Myocardial Ischemia-Reperfusion Injury by Improving Mitochondrial Function

Purpose

Myocardial ischemia-reperfusion injury (MI/RI) is associated with increased oxidative damage and mitochondrial dysfunction, resulting in an elevated risk of mortality. MI/RI may be alleviated by protecting cardiomyocytes from oxidative stress. Lutein, which belongs to a class of carotenoids, has proven to be effective in cardiovascular disease treatment due to its remarkable antioxidant properties, but its application is limited due to its poor stability and low bioavailability in vivo.

Methods

In this study, a delivery system was developed based on distearoyl phosphatidyl ethanolamine (DSPE)-thiol-ketone (TK)-PEG2K (polyethylene glycol 2000) (abbreviated as DTP) and PCM-SH (CWLSEAGPVVTVRALRGTGSW) to deliver lutein (abbreviated as lutein@DTPP) to damaged myocardium. First, lutein, lutein@DTP, or lutein@DTPP were injected through the tail vein once a day for 3 days and then MI/RI model rats were established by exposing rats to ischemia for 45 min and reperfusion for 6 h. We employed a range of experimental techniques including qRT-PCR, Western blotting, transmission electron microscopy, immunohistochemistry, immunofluorescence, flow cytometry, immunoprecipitation, molecular docking, and molecular dynamics simulations.

Results

Lutein@DTPP exhibited good myocardial targeting and ROS-responsive release. Our data suggested that lutein@DTPP effectively suppresses ferroptosis in cardiomyocytes. Mechanistically, we observed an upregulation of mouse double minute-2 (MDM2) in the hearts of MI/RI models and cardiomyocytes exposed to hypoxia/reoxygenation (H/R) conditions. In addition, NADH-ubiquinone oxidoreductase 75 kDa Fe-S protein 1 (NDUFS1) translocation from the cytosol to the mitochondria was inhibited by MDM2 upregulation. Notably, no significant variation in the total NDUFS1 expression was observed in H/R-exposed cardiomyocytes following treatment with siMDM2. Further study indicated that lutein facilitates the translocation of NDUFS1 from the cytosol to mitochondria by directly binding and sequestering MDM2, thereby improving mitochondrial function and inhibiting ferroptosis.

Conclusion

Lutein@DTPP promoted the mitochondrial translocation of NDUFS1 to restore mitochondrial function and inhibited the ferroptosis of cardiomyocytes by directly binding and sequestering MDM2.

Development of a hybrid rhodamine-hydrazine NIR fluorescent probe for sensitive detection and imaging of peroxynitrite in necrotizing enterocolitis model

This study describes the synthesis and characterization of a novel near-infrared (NIR) fluorescent probe RBNE based on a hybrid rhodamine dye, which shows excellent optical capability for detecting and imaging ONOO- in necrotizing enterocolitis (NEC) mouse model. The probe RBNE undergoes hydrazine redox-process, and subsequently the spirocyclic structure's opening, resulting in a turn-on fluorescence emission with the presence of ONOO-, which exhibits several excellent features, including a significant Stokes shift of 108 nm, near-infrared emission at 668 nm, a lower detection limit of 56 nM, low cytotoxicity, and excellent imaging ability for ONOO- both in vitro and in vivo. The presented study introduces a novel optical tool that has the potential to significantly advance our understanding of peroxynitrite (ONOO-) behaviors in necrotizing enterocolitis (NEC).

Strategically Engineered Ru(II) Complexes with Enhanced ROS Activity Enabling Potent Sonodynamic Effect against Multidrug-Resistant Biofilms

Sonodynamic therapy (SDT) can generate reactive oxygen species (ROS) to combat multidrug-resistant biofilms, which pose significant challenges to human health. As the key to producing ROS in SDT, the design of sonosensitizers with optimal molecular structures for sufficient ROS generation and activity in complex biofilm matrix is essential. In this study, we propose a π-expansion strategy and synthesize a series of small-molecule metal Ru(II) complexes (Ru1-Ru4) as sonosensitizers (Ru1-Ru4) to enhance the efficacy of SDT. Among these complexes, Ru4 demonstrates remarkable ROS generation capability (∼65.5-fold) that surpasses most commercial sonosensitizers (1.3- to 6.7-fold). Through catalyzing endogenous H2O2 decomposition, Ru4 facilitates the production of abundant O2 as a resource for 1O2 and the generation of new ROS (i.e., •OH) for improving SDT. Furthermore, Ru4 maintains the sustained ROS activity via consuming the interferences (e.g., glutathione) that react with ROS. Due to these unique advantages, Ru4 exhibits potent biofilm eradication ability against methicillin-resistant Staphylococcus aureus (MRSA) both in vitro and in vivo, underscoring its potential use in clinical settings. This work introduces a new approach for designing effective sonosensitizers to eliminate biofilm infections, addressing a critical need in healthcare management.

A NIR-Light-Activated and Lysosomal-Targeted Pt(II) Metallacycle for Highly Potent Evoking of Immunogenic Cell Death that Potentiates Cancer Immunotherapy of Deep-Seated Tumors

Though platinum (Pt)-based complexes have been recently exploited as immunogenic cell death (ICD) inducers for activating immunotherapy, the effective activation of sufficient immune responses with minimal side effects in deep-seated tumors remains a formidable challenge. Herein, we propose the first example of a near-infrared (NIR) light-activated and lysosomal targeted Pt(II) metallacycle (1) as a supramolecular ICD inducer. 1 synergistically potentiates immunomodulatory response in deep-seated tumors via multiple-regulated approaches, involving NIR light excitation, boosted reactive oxygen species (ROS) generation, good selectivity between normal and tumor cells, and enhanced tumor penetration/retention capabilities. Specifically, 1 has excellent depth-activated ROS production (~7 mm), accompanied by strong anti-diffusion and anti-ROS quenching ability. In vitro experiments demonstrate that 1 exhibits significant cellular uptake and ROS generation in tumor cells as well as respective multicellular tumor spheroids. Based on these advantages, 1 induces a more efficient ICD in an ultralow dose (i.e., 5 μM) compared with the clinical ICD inducer-oxaliplatin (300 μM). In vivo, vaccination experiments further demonstrate that 1 serves as a potent ICD inducer through eliciting CD8+/CD4+ T cell response and Foxp3+ T cell depletion with negligible adverse effects. This study pioneers a promising avenue for safe and effective metal-based ICD agents in immunotherapy.

NIR-II Responsive Fe-Doped Carbon Nanoparticles for Photothermal-Enhanced Chemodynamic Synergistic Oncotherapy

Phototherapy has demonstrated substantial development because in the second near-infrared (NIR-II) window it has a larger tissue penetration and fewer adverse consequences. In this work, a particular kind of NIR-II responsive Fe-doped carbon nanoparticles (FDCNs) is synthesized using a one-pot hydrothermal method for combined photothermal and chemodynamic therapy. The mesoporous nanostructure of FDCN, which has a size distribution that exceeds 225 nm, allows for effective acidification. The iron ions released from these nanoparticles can catalyze the decomposition of hydrogen peroxide (H2O2) into hydroxyl radical (•OH) for chemodynamic therapy (CDT). In addition to their CDT utility, FDCN can effectively adsorb and transform 1064 nm light into local heat, achieving a photothermal conversion efficacy (PCE) of 36.3%. This dual functionality not only allows for the direct eradication of cancer cells through photothermal therapy (PTT) but also enhances the chemodynamic reaction, creating a synergistic effect that amplifies the therapeutic outcome. The FDCN has demonstrated remarkable anticancer activity in both cellular and animal tests without incurring major systemic toxicity. This suggests that the compound has great promise for use in clinical cancer therapy.

A novel NIR-II fluorescent probe for hydrogen peroxide detection in drug-induced liver injury

The synthesis of H2O2-activatable small molecules in the second near-infrared (NIR-II) window remains challenging. We present the NIR-II probe Z-1065 for real-time detection of H2O2. Z-1065 demonstrates high sensitivity and selectivity towards H2O2in vitro and effectively monitors H2O2 generation in drug-induced liver injury (DILI) mouse models.

Mitochondria-targeted sonodynamic modulation of neuroinflammation to protect against myocardial ischemia‒reperfusion injury

Sympathetic hyperactivation and inflammatory responses are the main causes of myocardial ischemia‒reperfusion (I/R) injury and myocardial I/R-related ventricular arrhythmias (VAs). Previous studies have demonstrated that light-emitting diodes (LEDs) could modulate post-I/R neuroinflammation, thus providing protection against myocardial I/R injury. Nevertheless, further applications of LEDs are constrained due to the low penetration depth (<1 cm) and potential phototoxicity. Low-intensity focused ultrasound (LIFU), an emerging noninvasive neuromodulation strategy with deeper penetration depth (∼10 cm), has been confirmed to modulate sympathetic nerve activity and inflammatory responses. Sonodynamic therapy (SDT), which combines LIFU with sonosensitizers, confers additional advantages, including superior therapeutic efficacy, precise localization of neuronal modulation and negligible side effects. Herein, LIFU and SDT were introduced to modulate post-myocardial I/R neuroinflammation to protect against myocardial I/R injury. The results indicated that LIFU and SDT inhibited sympathetic neural activity, suppressed the activation of astrocytes and microglia, and promoted microglial polarization towards the M2 phenotype, thereby attenuating myocardial I/R injury and preventing I/R-related malignant VAs. These insights suggest that LIFU and SDT inspire a noninvasive and efficient neuroinflammatory modulation strategy with great clinical translation potential thus benefiting more patients with myocardial I/R in the future. STATEMENT OF SIGNIFICANCE: Myocardial ischemia-reperfusion (I/R) may cause I/R injury and I/R-induced ventricular arrhythmias. Sympathetic hyperactivation and inflammatory response play an adverse effect in myocardial I/R injury. Previous studies have shown that light emitting diode (LED) can regulate I/R-induced neuroinflammation, thus playing a myocardial protective role. However, due to the low penetration depth and potential phototoxicity of LED, it is difficult to achieve clinical translation. Herein, we introduced sonodynamic modulation of neuroinflammation to protect against myocardial I/R injury, based on mitochondria-targeted nanosonosensitizers (CCNU980 NPs). We demonstrated that sonodynamic modulation could promote microglial autophagy, thereby preventing myocardial I/R injury and I/R-induced ventricular arrhythmias. This is the first example of sonodynamic modulation of myocardial I/R-induced neuroinflammation, providing a novel strategy for clinical translation.

Rod-Shaped Au@Ce Nano-Platforms for Enhancing Photodynamic Tumor Collaborative Therapy

Tumor photodynamic therapy (PDT) relies on intratumoral free radicals, while the limited oxygen source and the depletion of tissue oxygen may exacerbate the hypoxia. As the treatment progresses, there will eventually be a problem of insufficient free radicals. Here, it is found that Au@CeO2 nano-rods (Au@Ce NRs), assembled by gold nano-rods (Au NRs) and ceria nanoparticles (CeO2 NPs), can efficaciously absorb near-infrared light (NIR) to promote the release of oxygen and free radicals. Au@Ce NRs exhibit a higher proportion of Ce3+ (Ce2O3) after oxygen release, while Ce3+ is subsequently oxidized to Ce4+ (CeO2) by trace H2O2. Interestingly, Au@Ce NRs re-oxidized by trace H2O2 can re-releasing oxygen and free radicals again upon NIR treatment, achieving oxygenation/oxygen evolution, similar to charging/discharging. This loop maximizes the conversion of limited oxygen source into highly cytotoxic free radicals. As a result, when B16-F10 cells are treated by NIR/Au@Ce NRs, more tumor cells undergo apoptosis, consistent with the higher level of free radicals. Importantly, NIR/Au@Ce NRs successfully suppresses tumor growth and promotes the generation of epidermal collagen fibers in the transplanted tumor model. Therefore, the rod-shaped Au@Ce NRs provide an ideal platform for maximizing the utilization of intratumoral oxygen sources and improving the treatment of melanoma.

Rationally Designed Benzobisthiadiazole-Based Covalent Organic Framework for High-Performance NIR-II Fluorescence Imaging-Guided Photodynamic Therapy

Although being applied as photosensitizers for photodynamic therapy, covalent organic frameworks (COFs) fail the precise fluorescence imaging in vivo and phototherapy in deep-tissue, due to short excitation/emission wavelengths. Herein, this work proposes the first example of NIR-II emissive and benzobisthiadiazole-based COF-980. Comparing to its ligands, the structure of COF-980 can more efficiently reducing the energy gap (ΔES1-T1) between the excited state and the triplet state to enhance photodynamic therapy efficiency. Importantly, COF-980 demonstrates high photostability, good anti-diffusion property, superior reactive oxygen species (ROS) generation efficiency, promising imaging ability, and ROS production in deep tissue (≈8 mm). Surprisingly, COF-980 combined with laser irradiation could trigger larger amount of intracellular ROS to high efficiently induce cancer cell death. Notably, COF-980 NPs precisely enable PDT guided by NIR-II fluorescence imaging that effectively inhibit the 4T1 tumor growth with negligible adverse effects. This study provides a universal approach to developing long-wavelength emissive COFs and exploits its applications for biomedicine.

Metal-organic framework (MOF)-based materials for pyroptosis-mediated cancer therapy

Pyroptosis is regarded as a promising strategy to modulate tumor immune microenvironments for anticancer therapy. Although pyroptosis inducers have been extensively explored in the biomedical field, their drug resistance, off-targeting capacity, and adverse effects do not fulfill the growing demands of therapy. Nowadays, metal-organic frameworks (MOFs) with unique structures and facile synthesis/functionalization characteristics have shown great potential in anticancer therapy. The flexible choices of metal ions and ligands endow MOFs with inherent anti-cancer efficiency, whereas the porous structures in MOFs make them ideal vehicles for delivering various chemodrug-based pyroptosis inducers. In this review, we provide the latest advances in MOF-based materials to evoke pyroptosis and give a brief but comprehensive review of the different types of MOFs for pyroptosis-mediated cancer therapy. Finally, we also discuss the current challenges of MOF-based pyroptosis inducers and their future prospects in this field.

Recent advances in combatting bacterial infections via well-designed metallacycles/metallacages

Bacterial infections can lead to the development of large-scale outbreaks of diseases that pose a serious threat to human life and health. Also, conventional antibiotics are prone to producing resistance and allergic reactions, and their therapeutic effect is dramatically diminished when bacterial communities form biofilms. Fortunately, well-designed supramolecular coordination complexes (SCCs) have been used as antibacterials or anti-biofilms in recent years. SCCs can kill bacteria by directly engaging with the bacterial surface through electrostatic interactions or by penetrating the bacterial membrane through the auxiliary effect of cell-penetrating peptides. Furthermore, scientists have engineered fluorescent SCCs that can produce reactive oxygen species (ROS) to eliminate bacteria when exposed to laser irradiation, and they also demonstrate outstanding performance in in vivo imaging, enabling integrated diagnosis and treatment. In this review, we summarize the design strategy and applications of SCCs in antibacterials or anti-biofilms and provide an outlook on future research.

Platelet membrane-based biochemotactic-targeting nanoplatform combining PDT with EGFR inhibition therapy for the treatment of breast cancer

Presently, the commonly used anti-tumor drugs lack targeting ability, resulting in a limited therapeutic efficacy and significant side effects. In this view, platelet membranes (PMs) not only exhibit specific binding of its P-selectin protein with CD44, which is highly expressed on breast cancer cells, to promote tumor-active targeting by PM biomimetic nanoplatforms, but also respond to vascular damage, thus inducing biochemotactic targeting to further facilitate the aggregation of these nanoplatforms. Therefore, in this study, a PM was applied to construct a biochemotactic-targeting nanotherapeutic platform based on dendritic large pore mesoporous silica nanoparticles (DLMSNs) co-loaded with chlorin e6 (Ce6) and lapatinib (LAP) to achieve the combination of photodynamic therapy (PDT) and EGFR inhibition therapy for breast cancer. Under laser irradiation, PM@DLMSN/Ce6/Lap could not only effectively kill breast tumor cells by the PDT, but also damage blood vessels. By combining the EGFR inhibition of LAP, PM@DLMSN/Ce6/Lap could better inhibit the migration and movement of tumor cells. In vitro and in vivo results showed that PM@DLMSN/Ce6/Lap could achieve active-targeting drug delivery to breast tumors and further recruit more nanoparticles to accumulate at tumor sites after the PDT-induced damage of blood vessels through biochemotactic targeting, achieving continuous EGFR inhibition to prevent tumor proliferation and metastasis. In conclusion, this study not only provides a new strategy for the clinical treatment of breast cancer, but also provides a design idea for improving the targeted delivery of anti-tumor drugs.

Cucurbit[8]uril Confinement-Based Secondary Coassembly for High-Efficiency Phosphorescence Energy Transfer Behavior

Aqueous supramolecular long-lived near-infrared (NIR) material is highly attractive but still remains great challenge. Herein, we report cucurbit[8]uril confinement-based secondary coassembly for achieving NIR phosphorescence energy transfer in water, which is fabricated from dicationic dodecyl-chain-bridged 4-(4-bromophenyl)-pyridine derivative (G), cucurbit[8]uril (CB[8]), and polyelectrolyte poly(4-styrene-sulfonic sodium) (PSS) via the hierarchical confinement strategy. As compared to the dumbbell-shaped G, the formation of unprecedented linear polypseudorotaxane G⊂CB[8] with nanofiber morphology engenders an emerging phosphorescent emission at 510 nm due to the macrocyclic confinement effect. Moreover, benefiting from the following secondary assembly confinement, such tight polypseudorotaxane G⊂CB[8] can further assemble with anionic polyelectrolyte PSS to yield uniform spherical nanoparticle, thereby significantly strengthening phosphorescence performance with an extended lifetime (i.e., 2.39 ms, c.f., 45.0 μs). Subsequently, the organic dye Rhodamine 800 serving as energy acceptor can be slightly doped into the polyelectrolyte assembly, which enables the occurrence of efficient phosphorescence energy transfer process with efficiency up to 80.1% at a high donor/acceptor ratio, and concurrently endows the final system with red-shifted and long-lived NIR emission (710 nm). Ultimately, the as-prepared assembly is successfully exploited as versatile imaging agent for NIR window labeling and detecting in living cells.

Multimodal Therapeutic Platforms Based on Self-Assembled Metallacycles/Metallacages for Cancer Radiochemotherapy

Discrete organometallic complexes with defined structures are proceeding rapidly in combating malignant tumors due to their multipronged treatment modalities. Many innovative superiorities, such as high antitumor activity, extremely low systemic toxicity, active targeting ability, and enhanced cellular uptake, make them more competent for clinical applications than individual precursors. In particular, coordination-induced regulation of luminescence and photophysical properties of organic light-emitting ligands has demonstrated significant potential in the timely evaluation of therapeutic efficacy by bioimaging and enabled synergistic photodynamic therapy (PDT) or photothermal therapy (PTT). This review highlights instructive examples of multimodal radiochemotherapy platforms for cancer ablation based on self-assembled metallacycles/metallacages, which would be classified by functions in a progressive manner. Finally, the essential demands and some plausible prospects in this field for cancer therapy are also presented.

Hemicyanine-based sensor for mitochondrial viscosity imaging in BV2 cells

Mitochondrial viscosity is a critical factor affecting numerous physiological processes, including phagocytosis. Abnormal viscosity in mitochondria is related to some pathological activities and diseases. Evaluating and detecting the changes in mitochondrial viscosity in vivo is crucial. Thus, a mitochondria-targeted red-emitting fluorescent probe (VP) was prepared, and can be used to detect viscosity with high selectivity and sensitivity. The synthesis of probe VP was as simple as two steps and the cost was low. In addition, the fluorescence intensity (log I615) exhibited an excellent relationship with viscosity (log η) in the range of 0.5 - 2.5 (R2 = 0.9985) in water/glycerol mixture. It is noteworthy that the probe VP displayed the highest signal-to-noise ratio (about 50-fold) for viscosity in water and glycerol system. The probe VP can visualize the mitochondrial viscosity change in living cells. More importantly, phagocytic test for BV2 cells further demonstrated that phagocytosis decreased with increased viscosity. Furthermore, VP was successfully used for monitoring the mitophagy process induced by starvation, and mitochondrial viscosity exhibited enhancement during mitophagy. The probe was a potential tool for studying viscosity and phagocytosis.

Recent advances on the construction of long-wavelength emissive supramolecular coordination complexes for photo-diagnosis and therapy

Recently, metal-based drugs have attracted relentless interest in the biomedical field. However, their short excitation/emission wavelengths and unsatisfactory therapeutic efficiency limit their biological applications in vivo. Currently, the second near-infrared window (NIR-II, 1000-1700 nm) provides more accurate imaging and therapeutic options. Thus, there has been a constant focus on developing multifunctional NIR metal agents for imaging and therapy that have deeper tissue penetration. Fortunately, supramolecular coordination complexes (SCCs) formed by the coordination-driven self-assembly of NIR-II emissive ligands can address the above issues. Importantly, metal receptors with chemotherapeutic properties in SCCs can bind to luminescent ligands, thus becoming a versatile therapeutic platform for chemotherapy, imaging and phototherapy. In this context, we systematically summarize the evolution of NIR-II emissive SCCs for biomedical applications and discuss future challenges and prospects.

Enzyme-Instructed Aggregation/Dispersion of Fluorophores for Near-Infrared Fluorescence Imaging In Vivo

Near-infrared (NIR) fluorescence is a noninvasive, highly sensitive, and high-resolution modality with great potential for in vivo imaging. Compared with "Always-On" probes, activatable NIR fluorescent probes with "Turn-Off/On" or "Ratiometric" fluorescent signals at target sites exhibit better signal-to-noise ratio (SNR), wherein enzymes are one of the ideal triggers for probe activation, which play vital roles in a variety of biological processes. In this review, we provide an overview of enzyme-activatable NIR fluorescent probes and concentrate on the design strategies and sensing mechanisms. We focus on the aggregation/dispersion state of fluorophores after the interaction of probes and enzymes and finally discuss the current challenges and provide some perspective ideas for the construction of enzyme-activatable NIR fluorescent probes.

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.