Ferroptosis is an Fe2+-dependent and lipid peroxidation-mediated regulated cell death. Its early detection is critical for diagnosis and timely intervention. Lipid hydrogen abstraction is the initiation step of the "lipid peroxidation-ferroptosis" cascade and an ideal target for early detection of ferroptosis. We developed the first set of fluorogenic probes for lipid H-abstraction, i.e., LHA585 for red, LHA675 for deep-red, and LHA930 for near-infrared. The key to their design is the use of 4-phenyl-3-methylbut-2-enyl, a close mimic of the polyunsaturated lipid, to specifically detect the highly oxidative radicals involved in ferroptosis. Notably, LHA585 yielded a fluorescence turn-on ca. 8 h earlier than the current gold-standard probe in an in vitro OGD/R model, highlighting its superiority for early detection of ferroptosis. While LHA585/675 is intended for in vitro studies, LHA930 was feasible for in vivo ferroptosis detection. Collectively, these findings establish LHAs as a robust advance for ferroptosis sensing, enabling in-depth mechanistic studies of lipid-peroxidation-driven cell death.

The rational design of controlled carbon monoxide-releasing molecules (CORMs) represents a pivotal step toward harnessing the therapeutic benefits of CO. This review systematically analyzes the chemical design of organic CORMs, categorizing them into acyclic, monocyclic, and bridged systems. Key release mechanisms such as hydrolysis, cycloreversion, and radical- or photo-triggered pathways are detailed, with emphasis on stimuli-responsive designs enabling spatiotemporally controlled, biocompatible, and logic-gated CO delivery.

In vivo imaging is the key to the success of transformative biomedical technologies. Currently, robust dyes absorbing and emitting in the shortwave infrared (SWIR) spectral region, i.e., 1000 nm and beyond, as well as a standard protocol to evaluate their performance in in vivo imaging, are sought after. Here, we report the rational design of the tetrabenzannulated silicon-rhodamine dye (ESi7), following the three-step guideline of benzannulation for long wavelength, steric shielding for stability, and deep rigidification for brightness and its convergent synthesis. Compared to its carbon-bridged predecessor (EC7), the highlights of ESi7 are its increased ring strain, reduced vibrational freedom, and improved fluorescence lifetime. ESi7 exhibits a remarkable fluorescence quantum yield of 0.19% in CH2Cl2, the highest for a small-molecule fluorophore absorbing/emitting at 1176/1275 nm to the best of our knowledge. Endowed by its long spectral wavelength, robust photo/chemo-stability, and high fluorescence brightness, in vivo mouse imaging with ESi7 set up a "PEAK" standard, an acronym for "Penetration depth, Exposure time, Acquisition duration, and Contrast".

Methicillin-resistant Staphylococcus aureus (MRSA) represents a major clinical challenge as a predominant pathogen causing chronic and difficult-to-treat wound infections. Effective strategies that simultaneously combat bacterial infection and promote tissue regeneration are essential yet challenging for managing MRSA-related wound complications. Herein, we report the design of a novel integrated dual-gas release molecular platform, which enable the phototriggered simultaneous release of NO and CO within a single molecular entity, i.e., an acylhydrazine-caged rhodamine (AhCR565). Green light initiates the cascade release of NO and CO from AhCR565, with a synchronized fluorescent turn-on signal, serving as an intrinsic calibration mechanism for real-time tracking of the localization, kinetics of dual gas release. The photodriven simultaneous release of NO and CO from AhCR565 demonstrates a superior antimicrobial effect against MRSA, while exhibiting excellent biocompatibility. By harnessing the synergistic and complementary bioactivities of NO and CO, AhCR565 effectively eradicates bacterial infections and promotes wound healing in a marine MRSA-infected skin wound model. This work highlights a promising noninvasive strategy for multigas simultaneous release therapy, providing a potent approach to tackling resistant bacterial infections and addressing broader biomedical challenges.

The shortwave infrared (SWIR) region is an ideal spectral window for next-generation bioimaging to harness improved penetration and reduced phototoxicity. SWIR spectral activity may also be accessed via supramolecular dye aggregation. Unfortunately, development of dye aggregation remains challenging. We propose a crystal-aided aggregate synthesis (CAASH) approach to introduce a layer of rationality for the development of J-aggregate and the successful development of a water-soluble SWIR JV-aggregate with a bisbenzannulated silicon rhodamine scaffold (ESi5). The resulting SWIR-aggregates exhibit excellent stabilities toward organic solvents, pH, sonication, photobleaching, thiols, and endogenous oxidative species. Notably, the aggregates have a high structure-dependent melting temperature of ca. 330-335 K. In fact, the heating/annealing process can be exploited to reduce aggregation disorder. The aggregates are biocompatible and have broad potential in in vivo fluorescence and photoacoustic imaging and more. While the shortwave infrared (SWIR) region has potential for bioimaging applications, stable and biocompatible SWIR absorbers/emitters are challenging to access. Here, the authors report the approach of crystal-aided aggregate synthesis for the development of J-aggregates for in vivo bioimaging.

With the rapid advancements in the field of fluorescent dyes, accurate prediction of optical properties and efficient retrieval of dye-related data are essential for effective dye design. However, there is a lack of tools for comprehensive data integration and convenient data retrieval. Moreover, existing prediction models mainly focus on a single property of fluorescent dyes and fail to account for the diverse fluorophores and solutions in a systematic manner. To address this, we proposed Fluor-predictor, a multitask prediction model for fluorophores. This study integrates multiple dye databases and develops an interpretable graph neural network-based multitask regression model to predict four key optical properties of fluorescent dyes. We thoroughly examined the impact of factors such as data quality and the number of solvents on model performance. By leveraging atomic weight contributions, the model not only predicts these properties but also provides insights to guide structural modifications. In addition, we compiled and built a comprehensive database containing 36,756 records of fluorescence properties. To address the limitations of existing models in accurate prediction of Xanthene and Cyanine dyes, we then compiled 1148 Xanthene dye records and 1496 Cyanine dye records from the literature, comparing direct training with transfer learning approaches. The model achieved mean absolute errors (MAE) of 11.70 nm, 15.37 nm, 0.096, and 0.091 for predicting absorption wavelength (λabs), emission wavelength (λem), quantum yield (Φ) and molar extinction coefficient (Log(ε)), respectively. We integrated this work into a tool, Fluor-predictor, which supports comprehensive retrieval methods and multiproperty prediction. Fluor-predictor will facilitate data retrieval, prescreening, and structural modification of dyes.

Near-infrared (NIR) triplet dyes are the cornerstones of cutting-edge biomedical and material applications. The difficulty in rational development of triplet dyes increases exponentially as the absorption wavelength shifts deeper into the NIR range. Although classical H-/J-typed packing of NIR dyes has the potential to enhance intersystem crossing (ISC) compared with that in single-chromophore dyes, the triplet state quantum yields remain limited in such strategy. Herein, proximal oblique-packed (V-shaped) heptamethine cyanines ( SZ780 ) through spiro-connection were achieved. Multi-channel ultrafast ISC were direct observed in SZ780 and a record high ISC rate constant (up to ~10 11  s −1 ) is registered among all the reported NIR triplet dyes. SZ780 exhibits a triplet state quantum yield of 18.9 % upon excitation at 750 nm, which is almost an order of magnitude higher than that of the monomer ( IR780 , 2.1 %) and nearly threefold increase compared to that of the H-packed dimer ( SC780 ) (6.7 %). Moreover, SZ780 efficiently generates singlet oxygen under 808 nm light irradiation, inducing cancer cell apoptosis in vivo. These findings demonstrate that constructing V-aggregated dyes system by spiro-connection offers a powerful approach for the design of high-performance NIR triplet sensitizers.

Fluorescence probes of reactive oxygen species in the near‐infrared (NIR) spectral region, i.e., 800 nm and beyond, are desired for in vivo biosensing, diagnosis, and pharmacology. However, the NIR dyes are typically prone to oxidative destruction, and the probes based on these dyes exhibit a poor fluorescence turn‐on ratio and a low detection sensitivity. EC5 is a bright and stable NIR fluorochromic scaffold and yet has not been exploited for probe design. Despite the structural analogy of EC5 to xanthene dyes, the classic spiro‐cyclization at the central methine carbon was surprisingly not applicable to EC5 . Here, we report the rational development of a novel probe design strategy for EC5 dye, i.e., asymmetric conjugative addition at the quinone‐methide carbon. EC5 ‐ H3 via this approach is a robust probe for highly oxidative species. Its merits include an ultrahigh turn‐on ratio of ca. 200‐fold and high resistance of the detection product toward ONOO − ‐mediated destruction. The feasibility of EC5 ‐ H3 for practical applications was showcased by in vivo biosensing of drug‐induced oxidative injuries to the liver. The high turn‐on ratio and high brightness of the probe allow tissue injuries to be imaged with confocal microscopy to reveal the heterogeneity in oxidative injuries to different liver cells.

With the rapid advancement of fluorescent dye research, there is an urgent need for tools capable of accurately predicting dye optical properties while facilitating structural modification. However, the field currently lacks reliable and user-friendly tools for this purpose. To address this gap, we have developed Fluor-tools—an integrated platform for dye property prediction and structural optimization. The platform comprises two core modules: (1) Fluor-pred, a dye property prediction model that integrates domain-specific knowledge of fluorophores with a label distribution smoothing (LDS) reweighting strategy and an advanced residual lightweight attention (RLAT) architecture. This model achieves state-of-the-art performance in predicting four key photophysical properties of dyes. (2) Fluor-opt, a structural optimization module that employs a matched molecular pair analysis (MMPA) method enhanced with symmetry-aware and environment-adaptive modifications. This module derives 1579 structural transformation rules, enabling the directional optimization of non-NIR (non-near-infrared) dyes to NIR properties. In summary, Fluor-tools provides robust computational support for research in biomedical imaging and optical materials. The platform is freely accessible at https://lmmd.ecust.edu.cn/Fluor-tools/.

Dysfunction of subcellular organelles initiates complex pathophysiological cascades and underlies numerous diseases, underscoring the need for organelle-specific therapeutic interventions. Precise spatiotemporal control of reactive oxygen species (ROS) generation within organelles offers a promising intervention approach. Herein, we report the design and synthesis of a novel series of organelle-targeted, photoactivatable acetylperoxyl radical donors (ACR575s) based on an acetyl-caged rhodamine scaffold. Blue light irradiation triggered the release of highly oxidative acetylperoxyl radicals, concomitantly generating a rhodamine dye for real-time monitoring. In vitro studies demonstrated the organelle-specific delivery of acetylperoxyl radicals, which subsequently induced concentration-dependent oxidative stress within specific subcellular compartments. Notably, this resulted in membrane damage and the modulation of macrophage polarization, providing clear evidence of the therapeutic potential of acetylperoxyl radicals in regulating redox balance and inflammatory responses. The ACR575 series provides a novel toolset for acetylperoxyl radical biology and subcellular redox regulation, enabling precise spatiotemporal control of acetylperoxyl radical-mediated oxidative stress and showing potential for applications in precise cancer therapy.

Hypoxia bioimaging attracts tremendous attention due to its profound implications in diagnosis of a range of pathological conditions. Nitroaromatics-based fluorescent probes are the most popular approach to tackle this problem. Despite intensive efforts of the field over the past 15 years and the development of a range of such probes, three challenges are still not addressed, i.e., highly sensitive probes necessitating a one-electron reduction, real-time monitoring probes with reversible sensing capability, and near-infrared probes with in vivo imaging potentials. Three groups have recently reported notable progresses regarding these challenges, which may spur another wave of development along this line of research and meet the need of real-world applications from researchers and doctors.

Peroxynitrite (ONOO-) is central to both physiological signaling and diverse pathological processes. Its dual nature underscores the need for precise tools to investigate its spatiotemporal dynamics and biological functions. However, the controlled generation and real-time tracking of ONOO- remain challenging due to its short half-life and high reactivity. Current small-molecule ONOO- donors often suffer from limitations such as slow release, low efficiency, and off-target effects. To overcome these challenges, here we report a new class of photo-triggered ONOO- donors (O-PND and Si-PND) based on a single rhodamine-derived scaffold, enabling precise ONOO- release with built-in fluorescence calibration. These molecular tools facilitate efficient ONOO- generation under blue light irradiation, as confirmed in PBS and live cells, and exhibit excellent cell membrane permeability. Upon intracellular activation, O-PND and Si-PND induced a marked increase in oxidative stress. However, further studies reveal that the rapid transient ONOO- burst in RAW264.7 cells was insufficient to significantly modulate macrophage polarization. Collectively, these robust self-reporting ONOO- donors provide a powerful single-molecule platform for investigating ONOO--mediated biological mechanisms with spatiotemporal precision.

The scarcity of high-performance fluorophores remains a formidable bottleneck in the rapidly advancing field of NIR-II imaging, as existing candidates suffer from low light absorptivity, poor emission efficiency, and cumbersome synthesis. Herein, we propose a straightforward 2-step cyclization strategy to construct an innovative highly bright NIR-II dye family designated as BM-engineering from readily available materials. BM dyes featured a fully rigid and coplanar skeleton, exhibiting superior molar extinction coefficient (εDCM = 1.9-3.7 × 105 M-1 cm-1), high fluorescence quantum yields (ΦF = 10.4-18.0% in DCM), and remarkable photochemical robustness. Notably, BM3 redefines the optical landscape with its exceptional NIR-II optical performance (ε = 3.7 × 105 M-1 cm-1, ΦF = 18.4%), solidifying its status as the brightest NIR-II fluorophore reported to date. Leveraging this advantage, BM3 achieves high-resolution bioimaging at ultralow doses, not only illuminating cerebral vasculature (3 nmol) and lymphatic vessels (75 pmol), but also accurately detecting subtle cerebral capillary damage in ischemia-reperfusion models. More strikingly, BM3 provides the first precise real-time tracking of inflamed lymphatic system triggered by both chemical and bacterial stimuli, unveiling distinct pathophysiological patterns that were previously elusive. Beyond experimental validation, computational analysis further deciphers the intricate relationship between molecular architecture and optical performance, offering new insight into the rational design of next-generation NIR-II fluorophores. This study not only pioneers a streamlined synthesis strategy toward ultrabright NIR-II fluorophores but also expands the frontiers of bioimaging precision and disease diagnostics, unlocking immense potential for biomedical innovations and clinical applications.

Parkinson's disease (PD) is a debilitating neurodegenerative disease, with current treatments primarily focusing on improving dopaminergic activity, providing symptomatic relief but failing to halt disease progression. Ferroptosis drives PD pathogenesis and is a potential therapeutic target. Herein, we introduce a novel peroxide-activated carbon monoxide (CO) donor, PCOD, featuring a streamlined structure designed to potentially enhance blood-brain barrier (BBB) penetration and optimize therapeutic outcomes. PCOD releases CO upon activation by nucleophilic peroxides, e.g., ONOO- and H2O2. This mechanism provides a potent strategy against ferroptosis: first, scavenging peroxides that generate oxidative radicals involved in ferroptosis, and second, CO is proposed to inhibit Fenton chemistry through coordination to Fe2+. In MPTP-treated mice, PCOD prevents dopaminergic neuron loss in the substantia nigra and alleviates PD symptoms. This peroxide-triggered CO release offers a promising and innovative strategy to combat ferroptosis and neurodegeneration in PD.

Bright near-infrared (NIR) dyes are the cornerstones of high-resolution imaging of scattering media and will transform biology, diagnosis, and surgery. Given that NIR fluorescence quantum yields are intrinsically low as dictated by the energy gap law, improving their molar absorptivity is the only alternative strategy to enhance the brightness of NIR fluorophores. Unfortunately, molar absorptivity still remains a gifted rather than an engineerable photophysical property throughout the long course of synthetic dye chemistry. Through an extensive review of the photophysical, structural, and environmental factors governing the molar absorptivity, we envisioned that the site-specific installation of optimized steric groups along the longitudinal axis can significantly enhance the molar absorptivity, along with stability, i.e., the quantum confinement effect. With an iterative structure-property relationship study of a total of 46 cyanine dyes, both the viability and broad scope of this strategy were established. Unprecedented superabsorbing cyanine dyes (ε > 4 × 105 cm-1 M-1) are commonplace in this library, and three Cy7/Cy9 dyes even exhibit molar absorptivity higher than 5 × 105 cm-1 M-1. NIR dyes as bright as fluorescein/rhodamine have been made available. This is a milestone in synthetic dye chemistry and paves the way for high-resolution NIR confocal imaging of intricate biological ultrastructures, e.g., hierarchical nephron structures, and more demanding bioimaging applications.

Weakly acidic pH, low oxygen and high glutathione levels are the main characteristics of tumor cells. Taking advantage of the unique acidic microenvironment of tumor cells, acid-responsive mesoporous organosilica nanoparticles (AMON) were designed for nitric oxide (NO)-sensitized chemotherapy of tumors. AMON served as a nanocarrier co-loaded with a nitric oxide donor (NOD) and chemotherapeutic drug doxorubicin (DOX). Transferrin (Tf) was modified on the surface as a targeting ligand to form NOD&DOX@AMON. In vitro experiments showed that AMON could be completely degraded under acidic conditions (pH 5.0) after 48h. NOD&DOX@AMON entered cells via transferrin receptor-mediated internalization and degraded in the acidic microenvironment to release its payloads. NOD released NO in presence of one-electron reducing substances like Glutathione (GSH) and ascorbic acid, inhibiting P-glycoprotein(P-gp) function and thereby increasing the intracellular concentration of DOX. In vivo distribution studies revealed that the nanohybrids accumulated maximally in tumor tissue 12h after intravenous injection and exhibited significant inhibitory effects on HepG2 xenograft tumors. Western blot experiments demonstrated that NOD&DOX@AMON could inhibit the expression of drug resistance-associated proteins and was expected to be employed as a therapeutic approach for drug-resistant ttumors.

Organic chromophores, especially those absorbing/emitting in the deep near-infrared region (deep-NIR, i.e., 800 nm and beyond), have prominent potentials in photothermal cancer therapy due to the deep tissue penetration and good biocompatibility. Although many cyanine/DAD-based photothermal agents have been successfully used in clinical and preclinical trials, they are limited to poor photostability and poor molar absorptivity. There is still an imperative demand for robust deep-NIR photothermal agents exhibiting high photostability and high molar absorptivity. We previously invented a bright push-pull fluorochromic scaffold (EC5) absorbing and emitting in the deep-NIR spectral region. In this work, EC5 was rationally tailored to suppress its fluorescence emission and promote its photothermal conversion efficiency. This led to the design and synthesis of EC5PM and EC5DP by changing two or four of its N-alkyl groups of the push-pull headgroups of EC5 into phenyl groups, respectively. The fluorescence intensities of EC5PM and EC5DP are completely quenched due to the TICT effect associated with the N-Ph bonds. In particular, EC5DP maximally absorbs at a longer wavelength of 879 nm with a superior photostability, a high photothermal conversion efficiency of 54.8%, and a superior molar extinction coefficient of 224,000 M(-1 )cm(-1). Upon encapsulation in DSPE-mPEG2000 micelles, the phototoxicity of EC5DP was showcased in 4T1 cells and a remarkable therapeutic effect of tumors was showcased with a 4T1 tumor-bearing mouse model. This work provides a rational strategy to design ultraphotostable and highly deep-NIR absorbing organic chromophores for photothermal therapy.

Photoimmunotherapy is a promising cancer treatment modality. While potent 1-e − oxidative species are known to induce immunogenic cell death (ICD), they are also associated with unspecific oxidation and collateral tissue damage. This difficulty may be addressed by post-generation radical reinforcement. Namely, non-oxidative radicals are first generated and subsequently activated into powerful oxidative radicals to induce ICD. Here, we developed a photo-triggered molecular donor ( NPCD565 ) of nitrosoperoxycarbonate (ONOOCO 2 − ), the first of its class to our knowledge, and further evaluated its feasibility for immunotherapy. Upon irradiation of NPCD565 by light within a broad spectral region from ultraviolet to red, ONOOCO 2 − is released along with a bright rhodamine dye ( RD565 ), whose fluorescence is a reliable and convenient build-in reporter for the localization, kinetics, and dose of ONOOCO 2 − generation. Upon photolysis of NPCD565 in 4T1 cells, damage-associated molecular patterns (DAMPs) indicative of ICD were observed and confirmed to exhibit immunogenicity by induced maturation of dendritic cells. In vivo studies with a bilateral tumor-bearing mouse model showcased the potent tumor-killing capability of NPCD565 of the primary tumors and growth suppression of the distant tumors. This work unveils the potent immunogenicity of ONOOCO 2 − , and its donor ( NPCD565 ) has broad potential for photo-immunotherapy of cancer.