Two cases of laparoscopic deroofing of giant liver cysts using indocyanine green fluorescence imaging

Laparoscopic deroofing (LD) for giant liver cysts using indocyanine green (ICG) fluorescence imaging was performed in two patients: a 53-year-old man with a 26-cm, symptomatic cyst and a 50-year-old woman with a 13-cm, symptomatic cyst. ICG fluorescence imaging can be used to easily identify the boundary between the liver parenchyma and the liver cyst. No postoperative bile leakage was observed in both patients. ICG fluorescence imaging is expected to become a desirable procedure in LD for giant liver cysts to reduce the occurrence of perioperative complications.

β-Galactosidase-activated near-infrared AIEgen for ovarian cancer imaging in vivo

Near-infrared (NIR) aggregation induced-emission luminogens (AIEgens) circumvent the noisome aggregation-caused quenching (ACQ) effect in physiological milieu, thus holding high promise for real-time and sensitive imaging of biomarkers in vivo. β-Galactosidase (β-Gal) is a biomarker for primary ovarian carcinoma, but current AIEgens for β-Gal sensing display emissions in the visible region and have not been applied in vivo. We herein propose an NIR AIEgen QM-TPA-Gal and applied it for imaging β-Gal activity in vitro and in ovarian tumor model. After being internalized by ovarian cancer cells (e.g., SKOV3), the hydrophilic nonfluorescent QM-TPA-Gal undergoes hydrolyzation by β-Gal to yield hydrophobic QM-TPA-OH, which subsequently aggregates into nanoparticles to turn NIR fluorescence "on" through the AIE mechanism. In vitro experimental results indicate that QM-TPA-Gal has a sensitive and selective response to β-Gal with a limit of detection (LOD) of 0.21 U/mL. Molecular docking simulation confirms that QM-TPA-Gal has a good binding ability with β-Gal to allow efficient hydrolysis. Furthermore, QM-TPA-Gal is successfully applied for β-Gal imaging in SKOV3 cell and SKOV3-bearing living mouse models. It is anticipated that QM-TPA-Gal could be applied for early diagnosis of ovarian cancers or other β-Gal-associated diseases in near future.

Dark-field imaging and fluorescence dual-mode detection of microRNA-21 in living cells by core-satellite plasmonic nanoprobes

The in situ precise quantification and simultaneous imaging of low abundance microRNAs (miRNAs) within living cells is critical for cancer diagnosis, yet it remains a significant challenge. Leveraging the excellent sensitivity and spatiotemporal resolution of dark-field microscopy (DFM) and fluorescence imaging, we have successfully devised a novel detection approach using dual-signal reporter probes (DSRPs). These probes allow for highly sensitive detection of miRNA-21 in living cells via toehold-mediated strand displacement cascades. The DSRPs were constructed by Au nanoparticles and Ag nanoclusters core-satellite nanostructures. After the recognition of miRNA-21, the strand displacement cascades were triggered, inducing the disassembly of the Au/Ag core-satellite nanostructure with apparent scattering intensity decrease and peak wavelength shifts. Additionally, the fluorescence of Ag clusters could be recovered and further enhanced when in close proximity to specific guanine-rich strands. The dual-signal response capability enables the accurate detection of miRNA-21 from 1 fM to 1 nM, with a limit of detection reached 0.75 fM. DFM and fluorescent imaging of living cells efficiently confirms the applicable detection of miRNA-21 in complex detection media. The biosensor based on DSRPs represents a promising nanoplatform for visual monitoring and imaging of biomolecules in living cells, even at the single particle level.

Advanced protein-embedded bimetallic nanocomposite optimized for in vivo fluorescence and magnetic resonance bimodal imaging

HYPOTHESIS

The development of bimodal imaging probes represents a hot topic of current research. Herein, we deal with developing an innovative bimodal contrast agent enabling fluorescence imaging (FI)/magnetic resonance imaging (MRI) and, simultaneously, consisting of biocompatible nanostructures. Optimized synthesis of advanced protein-embedded bimetallic (APEBM) nanocomposite containing luminescent gold nanoclusters (AuNC) and superparamagnetic iron oxide nanoparticles (SPION), suitable for in vivo dual-modal FI/MR imaging is reported.

EXPERIMENTS

The APEBM nanocomposite was prepared by a specific sequential one-pot green synthetic approach that is optimized to increase metals (Au, Fe) content and, consequently, the imaging ability of the resulting nanostructures. The protein matrix, represented by serum albumin, was intentionally chosen, and used since it creates an efficient protein corona for both types of optically/magnetically-susceptible nanostructures (AuNC, SPION) and ensures biocompatibility of the resulting APEBM nanocomposite although it contains elevated metal concentrations (approx. 1 mg·mL-1 of Au, around 0.3 mg·mL-1 of Fe). In vitro and in vivo imaging was performed.

FINDINGS

Successful in vivo FI and MRI recorded in healthy mice corroborated the applicability of the APEBM nanocomposite and, simultaneously, served as a proof of concept concerning the potential future exploitation of this new FI/MRI bimodal contrast agent in preclinical and clinical practice.

Multichannel-optical imaging for in vivo evaluating the safety and therapeutic efficacy of stem cells in tumor model in terms of cell tropism, proliferation and NF-κB activity

Stem cell-based cancer treatment has garnered significant attention, yet its safety and efficacy remain incompletely understood. The nuclear factor-kappa B (NF-κB) pathway, a critical signaling mechanism involved in tumor growth, angiogenesis, and invasion, serves as an essential metric for evaluating the behavior of stem cells in tumor models. Herein, we report the development of a triple-channel imaging system capable of simultaneously monitoring the tropism of stem cells towards tumors, assessing tumor proliferation, and quantifying tumor NF-κB activity. In this system, we generated a CRISPR-Cas9 gene-edited human glioblastoma cell line, GE-U87-MG, which provided a reliable readout of the proliferation and NF-κB activity of tumors by EF1α-RFLuc- and NF-κB-GLuc-based bioluminescent imaging, respectively. Additionally, near infrared-II emitting Tat-PEG-AgAuSe quantum dots were developed for tracking of stem cell tropism towards tumor. In a representative case involving human mesenchymal stem cells (hMSCs), multichannel imaging revealed no discernible effect of hMSCs on the proliferation and NF-κB activity of GE-U87-MG tumors. Moreover, hMSCs engineered to overexpress the necrosis factor-related apoptosis-inducing ligand were able to inhibit NF-κB activity and growth of GE-U87-MG in vivo. Taken together, our imaging system represents a powerful and feasible approach to evaluating the safety and therapeutic efficacy of stem cells in tumor models.

Dual biomarkers-activatable hollow MnO2-Based theranostic nanoplatform for efficient breast cancer-specific multisite fluorescence imaging and synergistic therapy

BACKGROUND

Theranostic nanoplatforms with integrated diagnostic imaging and multiple therapeutic functions play a vital role in precise diagnosis and efficient treatment for breast cancer, but unfortunately, these nanoplatforms are usually stuck in single-site imaging and single mode of treatment, causing unsatisfactory diagnostic and therapeutic efficiency. Herein, a dual biomarkers-activatable facile hollow mesoporous MnO2 (H-MnO2)-based theranostic nanoplatform, DNAzyme@H-MnO2-MUC1 aptamer (DHMM), was constructed for the simultaneous multi-site diagnosis and multiple treatment of breast cancer.

RESULTS

The DHMM acted as an integrated diagnostic and therapeutic nanoplatform that realizes multi-site fluorescence imaging-guided high-efficient photothermal/chemodynamic/gene synergistic therapy (PTT/CDT/GT) for breast cancer. The H-MnO2 exhibits high loading capacity for Cy5-MUC1 aptamer (3.05 pmoL μg-1) and FAM-DNAzyme (3.37 pmoL μg-1), and excellent quenching for the probes. In the presence of MUC1 on the cell membrane and GSH in the cytoplasm, Cy5-MUC1 aptamer and FAM-DNAzyme was activated triggering dual-channel fluorescence imaging at different sites. Moreover, the self-supplied Mn2+ was further supplied as DNAzyme cofactors to catalytic cleavage intracellular EGR-1 mRNA for high-efficient GT and stimulated the Fenton-like reaction for CDT. The H-MnO2 also showcases a favorable photothermal performance with a photothermal conversion efficiency of 44.16%, which ultimately contributes to multi-site fluorescence imaging-guided synergistic treatment with an apoptosis rate of 71.82%.

SIGNIFICANCE

This dual biomarker-activatable multiple therapeutic nanoplatform was realized multi-site fluorescence imaging-guided PTT/CDT/GT combination therapy for breast cancer with higher specificity and efficiency, which provides a promising theranostic nanoplatform for the precision and efficiency of breast cancer treatment.

Azoanthracene-core structure as Cu2+-assisted CO sensing probe: Characterization, performance, and bioimaging

Detection of endogenous CO (carbon monoxide) is an interesting topic in biology because it has been discovered as a messenger for signal transduction and therapeutic effects in vital biological activities. Fluorescence imaging has proven a powerful tool for detecting endogenous CO, which drives the development of low-cost and easy-to-use fluorescent probes. In this study, four azobenzene derivatives (A1, A2, A3, and A4) with various substituents were reported, including their geometric structures, photophysical parameters, and spectral responses to Cu2+ and CO. The relationship between substituent structure and performance was discussed along with Cu2+ quenching and CO sensing mechanisms. The optimal probe (A1), which had no substituent, efficiently quenched fluorescence in the presence of Cu2+, with its PLQY decreased from 0.33 to 0.02, PLQY = photoluminescence quantum yield. Upon CO deoxidization, A1's fluorescence could be recovered (PLQY recovered to 0.32) within 180 s. Its sensing mechanism was static by forming a non-fluorescent complex with Cu2+ (with a stoichiometric ratio of 1:1). The bioimaging performance of A1 for endogenous CO in HeLa cells was reported.

A novel lysosome-targeted fluorescent probe for precise formaldehyde detection in water samples, living cells and breast cancer tumors

This study investigated the potential ability of the fluorescent probe Ly-CHO to detect formaldehyde (FA) in living cells and tumor-bearing mice. Ly-CHO exhibited great selectivity, excellent sensitivity, and rapid response to FA, making it a valuable tool for tracking FA concentration changes. The probe was also found to target lysosomes specifically. Furthermore, Ly-CHO showed an obvious fluorescence increase in endogenous CHO detection after adding tetrahydrogen folic acid (THFA). This study validated Ly-CHO's possibility for FA imaging in vivo, with potential applications in understanding formaldehyde-related diseases.

An asymmetrical flavylium based probe with large Stokes shift and near infrared emission for highly sensitive detecting and visualizing cellular drug induced H2S fluctuations

Hydrogen sulfide (H2S) has been recognized as an important gaseous signaling molecule in living systems, and is of great significance in many pathological and physiological processes. Misregulation of endogenous H2S is implicated in various diseases in the neuronal, gastrointestinal, circulatory, and endocrine systems. Fluorescent probe with large Stokes shift and near infrared emission, is ideal candidate for imaging applications to prevent excitation scattering, autofluorescence interference, matrix absorption caused signal loss, and sample destruction. In this study, a dual-side expansion approach was performed to develop spectra tunable hydroxyl functional flavylium derivative named HN8 with enlarged Stokes shift of 81 nm, lengthened emission of 671 nm, satisfied quantum yield of 0.23, and good fluorescence enhancement factor of 14.3-fold. Moreover, based on HN8, the screened probe HN8DNP displayed 225-fold fluorescence enhancement containing linear correlations to H2S from 0 to 50 μM with good limit of detection (LOD) of 0.31 μM. Therefore, HN8DNP was then applied for imaging exogenous H2S and drug induced enzymatic H2S generation in living cells with satisfied results, revealing the relationship between intracellular H2S levels and related enzyme activities. In a word, the present work provided a potential fluorescence probe for highly selective and sensitive detecting H2S in vitro and in living cells. And the promising dual-side expansion strategy for regulation optical feature of traditional fluorophore may meet the increasing requirements of sensing and imaging applications.

Mitoxantrone encapsulated photosensitizer nanomicelle as carrier-free theranostic nanomedicine for near-infrared fluorescence imaging-guided chemo-photodynamic combination therapy on cancer

Combination therapy exhibits higher efficacy than any single therapy, inspiring various nanocarrier-assisted multi-drug co-delivery systems for the combined treatment of cancer. However, most nanocarriers are inert and non-therapeutic and have potential side effects. Herein, an amphiphilic polymer composed of a hydrophobic photosensitizer and hydrophilic poly(ethylene glycol) was employed as the nanocarriers and photosensitizers to encapsulate the chemotherapeutic drug mitoxantrone for chemo-photodynamic combination therapy. The resulting nanodrug consisted solely of pharmacologically active ingredients, thus avoiding potential toxicity induced by inert excipients. This multifunctional nanoplatform demonstrated significantly superior treatment performance compared to monotherapy for colorectal cancer, both in vitro and in vivo, achieving near-infrared fluorescence imaging-mediated chemo-photodynamic combined eradication of malignancy.

A Pyroglutamate Aminopeptidase 1 Responsive Fluorescence Imaging Probe for Real-Time Rapid Differentiation between Thyroiditis and Thyroid Cancer

Current diagnostic methods for thyroid diseases, including blood tests, ultrasound, and biopsy, always have difficulty diagnosing thyroiditis accurately, occasionally mistaking it for thyroid cancer. To address this clinical challenge, we developed Ox-PGP1, a novel fluorescent probe realizing rapid, noninvasive, and real-time diagnostic techniques. This is the first imaging tool capable of noninvasively distinguishing between thyroiditis and thyroid cancer. Ox-PGP1 was introduced as a fluorescent probe custom-built for the specific detection and quantification of pyroglutamate aminopeptidase 1 (PGP-1), a known pivotal biomarker of inflammation. Ox-PGP1 overcame the disadvantages of traditional enzyme-responsive fluorescent probes that relied on the intramolecular charge transfer (ICT) mechanism, including the issue of high background fluorescence, while offering exceptional photostability under laser irradiation. The spectral properties of Ox-PGP1 were meticulously optimized to enhance its biocompatibility. Furthermore, the low limit of detection (LOD) of Ox-PGP1 was determined to be 0.09 μg/mL, which demonstrated its remarkable sensitivity and precision. Both cellular and in vivo experiments validated the capacity of Ox-PGP1 for accurate differentiation between normal, inflammatory, and cancerous thyroid cells. Furthermore, Ox-PGP1 showed the potential to rapidly and sensitively differentiate between autoimmune thyroiditis and anaplastic thyroid carcinoma in a mouse model, achieving results in just 5 min. The successful design and application of Ox-PGP1 represent a substantial advancement in technology over traditional diagnostic approaches, potentially enabling earlier interventions for thyroid diseases.

Stable Super-Resolution Imaging of Cell Membrane Nanoscale Subcompartment Dynamics with a Buffering Cyanine Dye

Super-resolution fluorescence imaging is a crucial method for visualizing the dynamics of the cell membrane involved in various physiological and pathological processes. This requires bright fluorescent dyes with excellent photostability and labeling stability to enable long-term imaging. In this context, we introduce a buffering-strategy-based cyanine dye, SA-Cy5, designed to identify and label carbonic anhydrase IX (CA IX) located in the cell membrane. The unique feature of SA-Cy5 lies in its ability to overcome photobleaching. When the dye on the cell membrane undergoes photobleaching, it is rapidly replaced by an intact probe from the buffer pool outside the cell membrane. This dynamic replacement ensures that the fluorescence intensity on the cell membrane remains stable over time. Under the super-resolution structured illumination microscopy (SIM), the cell membrane can be continuously imaged for 60 min with a time resolution of 20 s. This extended imaging period allows for the observation of substructural dynamics of the cell membrane, including the growth and fusion of filamentous pseudopodia and the fusion of vesicles. Additionally, this buffering strategy introduces a novel approach to address the issue of poor photostability associated with the cyanine dyes.

A mitochondria-targeted ratiometric fluorescent sensor based on naphthalimide derivative-functionalized silica-based nanodots for imaging formaldehyde in living cells and zebrafish

A mitochondria-targeted ratiometric fluorescent sensor (Mito-Si-NA) for formaldehyde (FA) has been constructed by functionalizing silica-based nanodots (silica-based ND). As the fluorescence reference and carrier, the silica-based ND conjugate with small molecule probe for FA via covalent. Further modifying with mitochondria targeting moiety enables the sensor to specifically target mitochondria. In the presence of FA, the emission of silica-based ND remain constant to act as an internal reference (445 nm) while the response signal of small molecule probe was gradually enhanced (545 nm). This sensor exhibits excellent selectivity towards FA with great changes of fluorescence intensity ratio values (I545/I445). The FA ratiometric fluorescence imaging in mitochondria was achieved successfully. In addition, the sensor was also successfully used for imaging FA in zebrafish. The good performance of Mito-Si-NA for FA bioimaging confirms that Mito-Si-NA is an appealing imaging tool to monitor FA in mitochondria and shows great potential to study the functions of FA on mitochondria.

"Zero" Intrinsic Fluorescence Sensing-Platforms Enable Ultrasensitive Whole Blood Diagnosis and In Vivo Imaging

Abnormal physiological processes and diseases can lead to content or activity fluctuations of biocomponents in organelles and whole blood. However, precise monitoring of these abnormalities remains extremely challenging due to the insufficient sensitivity and accuracy of available fluorescence probes, which can be attributed to the background fluorescence arising from two sources, 1) biocomponent autofluorescence (BCAF) and 2) probe intrinsic fluorescence (PIF). To overcome these obstacles, we have re-engineered far-red to NIR II rhodol derivatives that possess weak BCAF interference. And a series of "zero" PIF sensing-platforms were created by systematically regulating the open-loop/spirocyclic forms. Leveraging these advancements, we devised various ultra-sensitive NIR indicators, achieving substantial fluorescence boosts (190 to 1300-fold). Among these indicators, 8-LAP demonstrated accurate tracking and quantifying of leucine aminopeptidase (LAP) in whole blood at various stages of tumor metastasis. Furthermore, coupling 8-LAP with an endoplasmic reticulum-targeting element enabled the detection of ERAP1 activity in HCT116 cells with p53 abnormalities. This delicate design of eliminating PIF provides insights into enhancing the sensitivity and accuracy of existing fluorescence probes toward the detection and imaging of biocomponents in abnormal physiological processes and diseases.

Activity-Based Fluorescence Diagnostics for Cancer

Fluorescence imaging is one of the most promising approaches to achieve intraoperative assessment of the tumor/normal tissue margins during cancer surgery. This is critical to improve the patients' prognosis, and therefore various molecular fluorescence imaging probes have been developed for the identification of cancer lesions during surgery. Among them, "activatable" fluorescence probes that react with cancer-specific biomarker enzymes to generate fluorescence signals have great potential for high-contrast cancer imaging due to their low background fluorescence and high signal amplification by enzymatic turnover. Over the past two decades, activatable fluorescence probes employing various fluorescence control mechanisms have been developed worldwide for this purpose. Furthermore, new biomarker enzymatic activities for specific types of cancers have been identified, enabling visualization of various types of cancers with high sensitivity and specificity. This Review focuses on recent advances in the design, function and characteristics of activatable fluorescence probes that target cancer-specific enzymatic activities for cancer imaging and also discusses future prospects in the field of activity-based diagnostics for cancer.

Towards developing a matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) compatible tissue expansion protocol

Mass spectrometry imaging (MSI) visualizes spatial distribution of molecules in a biological tissue. However, compared with traditional microscopy-based imaging, conventional MSI is limited to its spatial resolution, resulting in difficulties in identifying detailed tissue morphological characters, such as lesion boundary or nanoscale structures. On the other hand, expansion microscopy, a tissue expansion method widely used in optical imaging to improve morphological details, has great potential to solve insufficient spatial resolution in mass spectrometry imaging (MSI). However, expansion microscopy was not originally designed for MSI, resulting in problems while combining expansion microscopy and MSI such as expanded sample fragility, vacuum stability and molecule loss during sample preparation. In this research we developed a MALDI MSI compatible expansion protocol by adjusting sample preparation methods during tissue expansion, successfully combining expansion microscopy with MSI. After tissue expansion the expanded sample can be readily applied to MALDI MSI sample preparation and further data acquisition. The MALDI MSI compatible expansion protocol has great potential to be widely applied in MALDI MSI sample preparation to facilitate improvement of MSI spatial resolution.

Optical imaging reveals chemotherapy-induced metabolic reprogramming of residual disease and recurrence

Fewer than 20% of triple-negative breast cancer patients experience long-term responses to mainstay chemotherapy. Resistant tumor subpopulations use alternative metabolic pathways to escape therapy, survive, and eventually recur. Here, we show in vivo, longitudinal metabolic reprogramming in residual disease and recurrence of triple-negative breast cancer xenografts with varying sensitivities to the chemotherapeutic drug paclitaxel. Optical imaging coupled with metabolomics reported an increase in non-glucose-driven mitochondrial metabolism and an increase in intratumoral metabolic heterogeneity during regression and residual disease in resistant MDA-MB-231 tumors. Conversely, sensitive HCC-1806 tumors were primarily reliant on glucose uptake and minimal changes in metabolism or heterogeneity were observed over the tumors' therapeutic life cycles. Further, day-matched resistant HCC-1806 tumors revealed a higher reliance on mitochondrial metabolism and elevated metabolic heterogeneity compared to sensitive HCC-1806 tumors. Together, metabolic flexibility, increased reliance on mitochondrial metabolism, and increased metabolic heterogeneity are defining characteristics of persistent residual disease, features that will inform the appropriate type and timing of therapies.

Second Near-Infrared Macrophage-Biomimetic Nanoprobes for Photoacoustic Imaging of Neuroinflammation

Neuroinflammation is a significant pathological event involving the neurodegenerative process associated with many neurological disorders. Diagnosis and treatment of neuroinflammation in its early stage are essential for the prevention and management of neurological diseases. Herein, we designed macrophage membrane-coated photoacoustic (PA) probes (MSINPs), with targeting specificities based on naturally existing target-ligand interactions for the early diagnosis of neuroinflammation. The second near-infrared dye, IR1061, was doped into silica as the core and was encapsulated with a macrophage membrane. In vitro as well as in vivo, the MSINPs could target inflammatory cells via the inflammation chemotactic effect. PA imaging was used to trace the MSINPs in a neuroinflammation mouse model and showed a great targeted effect of MSINPs in the prefrontal cortex. Therefore, the biomimetic nanoprobe prepared in this study offers a new strategy for PA molecular imaging of neuroinflammation, which can enhance our understanding of the evolution of neuroinflammation in specific brain regions.

A near-infrared AIE fluorescent probe for accurate detection of sulfur dioxide derivatives and visualization of fingerprints

In most biophysiological processes, sulfur dioxide (SO2) is an important intracellular signaling molecule that plays an important role. The change of SO2 in cells are closely related to various diseases such as neurological disorders and lung cancer, so it is necessary to develop fluorescent probes with the ability to accurately detect SO2 during physiological processes. In this work, we designed and synthesized a multifunctional fluorescent probe TIS. TIS has excellent properties such as near-infrared emission, large stokes shift, excellent SO2 detection capabilities, low detection limit, high specificity and visualization of color change before and after reaction. Simultaneously, TIS has low cytotoxicity, good biocompatibility, clear cell imaging capability and mitochondrial targeting ability. In addition, the ability of TIS to be applied to different material surfaces for latent fingerprint fluorescence imaging was also explored. TIS provides an excellent method for the accurate detection of SO2 derivatives and shows great potential applications in near-infrared cellular imaging and latent fingerprint fluorescence imaging.

Development of an activatable Lysosome-targeted fluorescent probe for the detection of endogenous ONOO- levels

The liver plays a crucial role in several important processes in the human body, including metabolism, detoxification, and immune function. When the liver experiences acute injury, it can cause significant harm and requires prompt detection. Traditional biomarkers lack specificity and cannot detect changes in real-time, making them unsuitable for monitoring pathological processes. Recent studies have shown that acute liver injury (ALI) is closely related to oxidative stress, with peroxynitrite (ONOO-) being a vital byproduct of liver metabolism and become a critical biomarker for detecting liver damage. As a result, this research developed an activatable near-infrared fluorescent probe W-3a that can be used to detect endogenous ONOO- in a mouse model of ALI induced by lipopolysaccharides (LPS). The probe has high selectivity and anti-interference ability, with a reaction time <10 min and a detection limit of 85 nM. It was successfully utilized in detecting endogenous ONOO- in cells and live imaging of ALI mice.

Multimodal Theranostic Nanoparticles for Necrosis Targeting, Fluorescence/SPECT Imaging, and Radiotherapy of Residual Tumors after Hepatocellular Carcinoma Ablation

Thermal ablation has been commonly used as an effective treatment for hepatocellular carcinoma; however, peri-necrotic tumor residues after ablation play a significant role in tumor recurrence and poor prognosis. Therefore, developing agents that can effectively target and eliminate residual tumors is critically needed. Necrosis targeting strategies have potential implications for evaluating tumor necrosis areas and treating the surrounding residual tumors. To address this issue, we have developed a biodegradable nanoparticle with necrosis avidity that is compatible with fluorescence imaging, single photon emission computed tomography (SPECT) imaging, and necrosis targeted radiotherapy. The nanoparticles were synthesized using iodine-131-labeled hypericin (131I-Hyp) as the core and amphiphilic copolymer poly(ethylene glycol)-block-poly(ε-caprolactone) (PEG-PCL) as the shell. The developed nanoparticle, PNP@(131I-Hyp), has a uniform spherical morphology with a size of 33.07 ± 3.94 and 45.93 ± 0.58 nm determined by cryogenic transmission electron microscopy (cryo-TEM) and dynamic light-scattering analysis (polydispersity index = 0.19 ± 0.01), respectively, and having a good stability and blood compatibility in vitro. In mouse subcutaneous ablated-residual tumor models, fluorescence and SPECT imaging demonstrated that PNP@(131I-Hyp) prominently accumulated in the tumor and was retained for as long as 168 h following intravenous injection. Moreover, ex vivo analyses showed that PNP@(131I-Hyp) mainly gathered in the necrotic zones of subcutaneous tumors and inhibited residual tumors by radiotherapy. In addition, histological examination of harvested organs and hematological analysis demonstrated that intravenous injection of 5 mCi/kg nanoparticles caused no gross abnormalities. This multifunctional nanoparticle, therefore, has necrosis imaging and targeted therapeutic effects on residual tumors after thermal ablation of hepatocellular carcinoma, showing potential for clinical application.

Advances in Bio-Optical Imaging Systems for Spatiotemporal Monitoring of Intestinal Bacteria

Vast and complex intestinal communities are regulated and balanced through interactions with their host organisms, and disruption of gut microbial balance can cause a variety of diseases. Studying the mechanisms of pathogenic intestinal flora in the host and early detection of bacterial translocation and colonization can guide clinical diagnosis, provide targeted treatments, and improve patient prognosis. The use of in vivo imaging techniques to track microorganisms in the intestine, and study structural and functional changes of both cells and proteins, may clarify the governing equilibrium between the flora and host. Despite the recent rapid development of in vivo imaging of intestinal microecology, determining the ideal methodology for clinical use remains a challenge. Advances in optics, computer technology, and molecular biology promise to expand the horizons of research and development, thereby providing exciting opportunities to study the spatio-temporal dynamics of gut microbiota and the origins of disease. Here, this study reviews the characteristics and problems associated with optical imaging techniques, including bioluminescence, conventional fluorescence, novel metabolic labeling methods, nanomaterials, intelligently activated imaging agents, and photoacoustic (PA) imaging. It hopes to provide a valuable theoretical basis for future bio-intelligent imaging of intestinal bacteria.

Spatial nonstationarity of image noise in widefield optical imaging and its effects on cluster-based inference for resting-state functional connectivity

BACKGROUND

Resting-state functional connectivity (RSFC) analysis with widefield optical imaging (WOI) is a potentially powerful tool to develop imaging biomarkers in mouse models of disease before translating them to human neuroimaging with functional magnetic resonance imaging (fMRI). The delineation of such biomarkers depends on rigorous statistical analysis. However, statistical understanding of WOI data is limited. In particular, cluster-based analysis of neuroimaging data depends on assumptions of spatial stationarity (i.e., that the distribution of cluster sizes under the null is equal at all brain locations). Whether actual data deviate from this assumption has not previously been examined in WOI.

NEW METHOD

In this manuscript, we characterize the effects of spatial nonstationarity in WOI RSFC data and adapt a "two-pass" technique from fMRI to correct cluster sizes and mitigate spatial bias, both parametrically and nonparametrically. These methods are tested on multi-institutional data.

RESULTS AND COMPARISON WITH EXISTING METHODS

We find that spatial nonstationarity has a substantial effect on inference in WOI RSFC data with false positives much more likely at some brain regions than others. This pattern of bias varies between imaging systems, contrasts, and mouse ages, all of which could affect experimental reproducibility if not accounted for.

CONCLUSIONS

Both parametric and nonparametric corrections for nonstationarity result in significant improvements in spatial bias. The proposed methods are simple to implement and will improve the robustness of inference in optical neuroimaging data.

Mechanistic analysis of the sub chronic toxicity of La and Gd in Daphnia magna based on TKTD modelling and synchrotron X-ray fluorescence imaging

The release of lanthanides (Ln) into the environment has increased in recent decades due to their expanding applications in society. Studying their toxicity in aquatic ecosystems is urgent and challenging, with contradictory evidence presented in the literature. This study compared the biodistribution of La and Gd in Daphnia magna exposed to sub-chronic conditions and developed the first Toxicokinetic-Toxicodynamic (TKTD) model for these lanthanides with this model crustacean. D. magna were initially exposed for 7 days to concentrations close to the LC50 of La (2.10 mg L-1) and Gd (1.70 mg L-1). After exposure, half of the live daphnids were introduced in a clean media to allow depuration over 24 h, while the other organisms were directly prepared for synchrotron imaging measurements. Synchrotron X-ray fluorescence analysis revealed that metal distribution in the organisms was similar for both La and Gd, predominantly localized in the intestinal tract, even after the depuration process. These results indicate that ingested metal can adversely affect organisms under sub-chronic exposure conditions, highlighting the importance of using nominal concentrations as a more suitable indicator of metal bioavailability for risk assessment. The General Unified Threshold Model of Survival (GUTS) TKTD framework, in its reduced form (GUTS-RED), was developed for La and Gd using dissolved and nominal concentrations. D. magna were exposed for 7 days to concentrations from 0.5 to 5 mg L-1 of La or Gd and mortality monitored daily. The mechanistic model revealed a faster toxicokinetics for La than Gd and a higher toxicity for Gd than La in the organism. This study confirmed, despite similar chemical properties, the variation in both toxicity and toxicokinetics between these two metals.

Micropolarity governs the structural organization of biomolecular condensates

Membraneless organelles within cells have unique microenvironments that play a critical role in their functions. However, how microenvironments of biomolecular condensates affect their structure and function remains unknown. In this study, we investigated the micropolarity and microviscosity of model biomolecular condensates by fluorescence lifetime imaging coupling with environmentally sensitive fluorophores. Using both in vitro and in cellulo systems, we demonstrated that sufficient micropolarity difference is key to forming multilayered condensates, where the shells present more polar microenvironments than the cores. Furthermore, micropolarity changes were shown to be accompanied by conversions of the layered structures. Decreased micropolarities of the granular components, accompanied by the increased micropolarities of the dense fibrillar components, result in the relocation of different nucleolus subcompartments in transcription-stalled conditions. Our results demonstrate the central role of the previously overlooked micropolarity in the regulation of structures and functions of membraneless organelles.

[Intraoperative stimulated Raman histology for personalized brain tumor surgery]

BACKGROUND

In brain tumor surgery a personalized surgical approach is crucial to achieve a maximum safe tumor resection. The extent of resection decisively depends on the histological diagnosis. Stimulated Raman histology (SRH), a fiber laser-based optical imaging method, offers the possibility for evaluation of an intraoperative diagnosis in a few minutes.

OBJECTIVE

To provide an overview on the applications of SRH in neurosurgery and transference of the technique to other surgical disciplines.

METHODS

Description of the technique and review of the current literature on SRH.

RESULTS

The SRH technique was successfully used in multiple neuro-oncological tumor entities. Initial pilot projects showed the potential for analysis of extracranial tumors.

CONCLUSION

The use of SRH provides a near real-time diagnosis with high diagnostic accuracy and provides further developmental potential to improve personalized tumor surgery.

A bubble-enhanced lanthanide-doped up/down-conversion platform with tumor microenvironment response for dual-modal photoacoustic and near-infrared-II fluorescence imaging

As an important tumor diagnosis strategy in precision medicine, multimodal imaging has been widely studied. However, the weak imaging signal with low spatial resolution and the constant signal of lack of specific activation severely limit its disease diagnosis. Herein, a bubble-enhanced lanthanide-based up/down-conversion platform with tumor microenvironment response for dual-mode imaging, LDNP@DMSN-Au@CaCO3 nanoparticles (named as LDAC NPs) were successfully developed. Combining the advantages of photoacoustic imaging (PAI) and the second near-infrared window (NIR-II) fluorescence imaging (FI), significantly improved the accuracy of diseases diagnosis. LDAC NPs with flower-like structure were synthesized through the encapsulation of uniform lanthanide-doped nanoparticles (NaYbF4:Ce,Er@NaYF4 named LDNPs) with dendritic mesoporous silica (DMSN). The gold nanoparticles (Au NPs) were then in situ grown on the surface of DMSN and the surface were finally coated with a layer of calcium carbonate (CaCO3). Under the excitation of the 980 nm laser, LDNPs showed strong emission of NIR-II at 1550 nm due to the doping of Ce and Er ions, showcasing excellent spatial resolution and deep tissue penetration characteristics, while the resulting visible light emission (540 nm) enables Au NPs to generate PAI signals with the aid of LDNPs via the fluorescence resonance energy transfer effect. In acidic tumoral environment, CaCO3 layer could produce CO2 microbubbles, and the PAI signals of LDAC NPs could be further enhanced with the generation of CO2 bubbles due to the bubble cavitation effect. Simultaneously, the NIR-II FI of LDAC NPs was self-enhanced with the degradation of the CaCO3. This intelligent nanoparticle with stimulus-activated dual-mode imaging capability holds great promise in future precision diagnostics.

A novel fluorescent probe for cascade detection of hydrogen sulfide and hypochlorous acid and its application in bioimaging

Herein we developed a cascade detection mode for the detection of HS- and ClO- by the novel probe NM-Cl bearing a conjugating naphthalene-dicyanoisophorone unit. The probe displayed sensitive and remarkable fluorescent enhancement in response to HS-, but not to other analytes. The mixture of probe and HS- constructed a specific sensing system for ClO- by fluorescent quenching response. The mechanism studies indicated that the successive reacting of HS- substitution Cl atom in probe and then addition of ClO- facilitation a thiofuran ring-forming induced differentiated fluorescence emission. This study provides a novel mechanism for the detection of HS- and ClO-, the imaging of cell and living animal further indicating the good application prospects of the probe in biosensing and bioimaging.

In Vivo Imaging of Liver Spheroids Engrafted in the Anterior Chamber of the Mouse Eye

Biomedical studies of the liver in mammals are hindered by the lack of methods for in vivo noninvasive longitudinal imaging at cellular resolution. Until now, optical imaging of the liver in situ is possible by intravital imaging, which offers high-resolution imaging at the cellular level but cannot be performed multiple times and, therefore, longitudinally in the same animal. Noninvasive imaging methods, such as bioluminescence, allow repeated imaging sessions on the same animal but do not achieve cell resolution. To address this methodology gap, we have developed a platform for noninvasive in vivo imaging of liver spheroids engrafted in the anterior chamber of the mouse eye. In the workflow described in this study, primary mouse liver spheroids are generated in vitro and transplanted into the anterior chamber of the eye of recipient mice, where they engraft on the iris. The cornea acts as a natural body window through which we can image the engrafted spheroids by conventional confocal microscopy. The spheroids survive for months in the eye, during which the cells can be studied in contexts of health and disease, as well as being monitored in response to different stimuli over repeated imaging sessions using appropriate fluorescent probes. In this protocol, we provide a breakdown of the necessary steps to implement this imaging system and explain how to best harness its potential.

The Monitoring and Cell Imaging of Fe3+ Using a Chromone-Based Fluorescence Probe

A new structurally simple fluorescent CP probe based on chromone was designed and synthesized, and its structure was fully characterized using various analytical techniques. The CP probe displays a high selectivity and sensitivity for sensing Fe3+ with a "turn-off" fluorescence response over other metal ions in a DMSO/H2O (4:1, v/v) solution. The experiment results show that the CP probe is stable over a wide pH range of 2.0-12.0. The detection limit for Fe3+ was calculated to be 0.044 μmol•L-1. The molar ratio method indicated that the binding mode between the CP probe and Fe3+ is a 1:1 complex formation. HR-MS and density functional theory (DFT) calculations were also performed to further confirm the recognition mechanism. Both fluorescence imaging experiments and the MTT assay demonstrated that the CP probe was suitable for detecting intracellular Fe3+ and no significant cytotoxicity in living cells.

Optical imaging of the intrinsic signal as a tool to characterize orientation sensitivity in the primary visual cortex of the young mouse

We employed intrinsic signal optical imaging (ISOI) to investigate orientation sensitivity bias in the visual cortex of young mice. Optical signals were recorded in response to the moving light gratings stimulating ipsi‑, contra‑ and binocular eye inputs. ISOI allowed visualization of cortical areas activated by gratings of specific orientation and temporal changes of light scatter during visual stimulation. These results confirmed ISOI as a reliable technique for imaging the activity of large populations of neurons in the mouse visual cortex. Our results revealed that the contralateral ocular input activated a larger area of the primary visual cortex than the ipsilateral input, and caused the highest response amplitudes of light scatter signals to all ocular inputs. Horizontal gratings moved in vertical orientation induced the most significant changes in light scatter when presented contralaterally and binocularly, surpassing stimulations by vertical or oblique gratings. These observations suggest dedicated integration mechanisms for the combined inputs from both eyes. We also explored the relationship between point luminance change (PLC) of grating stimuli and ISOI time courses under various orientations of movements of the gratings and ocular inputs, finding higher cross-correlation values for cardinal orientations and ipsilateral inputs. These findings suggested specific activation of different neuronal assemblies within the mouse's primary visual cortex by grating stimuli of the corresponding orientation. However, further investigations are needed to examine this summation hypothesis. Our study highlights the potential of optical imaging as a valuable tool for exploring functional‑anatomical relationships in the mouse visual system.

[Effect of dual fluorescence imaging in identifying central lymph nodes and parathyroid glands during thyroid cancer surgery]

Objective: To investigate the effect of dual fluorescence imaging in identifying central lymph nodes and parathyroid glands during thyroid cancer surgery. Methods: This study was a cross-sectional study. Patients who underwent surgery for papillary thyroid cancer (PTC) at the Department of Head and Neck Surgery, Beijing Tongren Hospital, Capital Medical University between January 2022 and September 2023 were included. All patients underwent thyroid lobectomy or total resection, and central lymph node dissection was performed at the same time. During the operation, tracing injection of mitoxantrone hydrochloride and 785 nm and 660 nm dual fluorescence imaging technique were used to measure the fluorescence intensity (FI) of parathyroid glands, central lymph nodes and background. After correcting to obtain the standardized FI, the paired t-test was used to compare the standardized FI of the parathyroid glands and central lymph nodes, and the Spearman's rank correlation analysis was used to analyze the relationship between the standardized FI and various clinical indicators. Results: The study included 30 patients (8 males and 22 females), with a mean age of (41.8±10.4) years. A total of 76 parathyroid glands and 234 central lymph nodes were identified under dual fluorescence imaging, and the standardized FI of parathyroid glands was less than that of central lymph nodes (44.7±16.8 vs 99.5±28.4, P<0.001). The visualization rate, false rate and miscut rate of parathyroid glands under 785 nm wavelength excitation light were 98.7% (76/77), 0 (0/77) and 1.3% (1/77), respectively (one case with no visualization and miscutting parathyroid gland was the encapsulated type). The visualization rate of central lymph nodes under 660 nm wavelength excitation light was 98.7% (234/237). There was no significant correlation between FI and clinical indicators such as gender, age, height, weight, body mass index, preoperative thyroid stimulating hormone, thyroglobulin antibody, thyroid microsomal antibody, serum calcium, parathyroid hormone level and surgical procedure (all P>0.05). Conclusion: Dual fluorescence imaging of central lymph nodes and parathyroid glands can improve the ability to identify parathyroid gland while assisting central lymph node dissection.

Tumor Microenvironment Activatable Nanoprodrug System for In Situ Fluorescence Imaging and Therapy of Liver Cancer

The development of new imaging and treatment nanoprodrug systems is highly demanded for diagnosis and therapy of liver cancer, a severe disease characterized by a high recurrence rate. Currently, available small molecule drugs are not possible for cancer diagnosis because of the fast diffusion of imaging agents and low efficacy in treatment due to poor water solubility and significant toxic side effects. In this study, we report the development of a tumor microenvironment activatable nanoprodrug system for the diagnosis and treatment of liver cancer. This nanoprodrug system can accumulate in the tumor site and be selectively activated by an excess of hydrogen peroxide (H2O2) in the tumor microenvironment, releasing near-infrared solid-state organic fluorescent probe (HPQCY-1) and phenylboronic acid-modified camptothecin (CPT) prodrug. Both HPQCY-1 and CPT prodrugs can be further activated in tumor sites for achieving more precise in situ near-infrared (NIR) fluorescence imaging and treatment while reducing the toxic effects of drugs on normal tissues. Additionally, the incorporation of hydrophilic multivalent chitosan as a carrier effectively improved the water solubility of the system. This research thus provides a practical new approach for the diagnosis and treatment of liver cancer.

Longitudinal intravital imaging of mouse placenta

Studying placental functions is crucial for understanding pregnancy complications. However, imaging placenta is challenging due to its depth, volume, and motion distortions. In this study, we have developed an implantable placenta window in mice that enables high-resolution photoacoustic and fluorescence imaging of placental development throughout the pregnancy. The placenta window exhibits excellent transparency for light and sound. By combining the placenta window with ultrafast functional photoacoustic microscopy, we were able to investigate the placental development during the entire mouse pregnancy, providing unprecedented spatiotemporal details. Consequently, we examined the acute responses of the placenta to alcohol consumption and cardiac arrest, as well as chronic abnormalities in an inflammation model. We have also observed viral gene delivery at the single-cell level and chemical diffusion through the placenta by using fluorescence imaging. Our results demonstrate that intravital imaging through the placenta window can be a powerful tool for studying placenta functions and understanding the placental origins of adverse pregnancy outcomes.

NIR-II Ratiometric Fluorescence Probes Enable Precise Determination of the Metastatic Status of Sentinel Lymph Nodes

Accurately determining the metastatic status of sentinel lymph nodes (SLNs) through noninvasive imaging with high imaging resolution and sensitivity is crucial for cancer therapy. Herein, we report a dual-tracer-based NIR-II ratiometric fluorescence nanoplatform combining targeted and nontargeted moieties to determine the metastatic status of SLNs through the recording of ratio signals. Ratiometric fluorescence imaging revealed approximately 2-fold increases in signals in tumor-draining SLNs compared to inflamed and normal SLNs. Additionally, inflamed SLNs were diagnosed by combining the ratio value with the enlarged size outputted by NIR-II fluorescence imaging. The metastatic status diagnostic results obtained through NIR-II ratiometric fluorescence signals were further confirmed by standard H&E staining, indicating that the ratiometric fluorescence strategy could achieve distant metastases detection. Furthermore, the superior imaging quality of ratiometric probes enables visualization of the detailed change in the lymphatic network accompanying tumor growth. Compared to clinically available and state-of-the-art NIR contrast agents, our dual-tracer-based NIR-II ratiometric fluorescence probes provide significantly improved performance, allowing for the quick assessment of lymphatic function and guiding the removal of tumor-infiltrating SLNs during cancer surgery.

Iterative nanoparticle bioengineering enabled by x-ray fluorescence imaging

Nanoparticles (NPs) are currently developed for drug delivery and molecular imaging. However, they often get intercepted before reaching their target, leading to low targeting efficacy and signal-to-noise ratio. They tend to accumulate in organs like lungs, liver, kidneys, and spleen. The remedy is to iteratively engineer NP surface properties and administration strategies, presently a time-consuming process that includes organ dissection at different time points. To improve this, we propose a rapid iterative approach using whole-animal x-ray fluorescence (XRF) imaging to systematically evaluate NP distribution in vivo. We applied this method to molybdenum-based NPs and clodronate liposomes for tumor targeting with transient macrophage depletion, leading to reduced accumulations in lungs and liver and eventual tumor detection. XRF computed tomography (XFCT) provided 3D insight into NP distribution within the tumor. We validated the results using a multiscale imaging approach with dye-doped NPs and gene expression analysis for nanotoxicological profiling. XRF imaging holds potential for advancing therapeutics and diagnostics in preclinical pharmacokinetic studies.

Highly robust reconstruction framework for three-dimensional optical imaging based on physical model constrained neural networks

Objective. The reconstruction of three-dimensional optical imaging that can quantitatively acquire the target distribution from surface measurements is a serious ill-posed problem. Traditional regularization-based reconstruction can solve such ill-posed problem to a certain extent, but its accuracy is highly dependent ona priorinformation, resulting in a less stable and adaptable method. Data-driven deep learning-based reconstruction avoids the errors of light propagation models and the reliance on experience and a prior by learning the mapping relationship between the surface light distribution and the target directly from the dataset. However, the acquisition of the training dataset and the training of the network itself are time consuming, and the high dependence of the network performance on the training dataset results in a low generalization ability. The objective of this work is to develop a highly robust reconstruction framework to solve the existing problems.Approach. This paper proposes a physical model constrained neural networks-based reconstruction framework. In the framework, the neural networks are to generate a target distribution from surface measurements, while the physical model is used to calculate the surface light distribution based on this target distribution. The mean square error between the calculated surface light distribution and the surface measurements is then used as a loss function to optimize the neural network. To further reduce the dependence ona prioriinformation, a movable region is randomly selected and then traverses the entire solution interval. We reconstruct the target distribution in this movable region and the results are used as the basis for its next movement.Main Results. The performance of the proposed framework is evaluated with a series of simulations andin vivoexperiment, including accuracy robustness of different target distributions, noise immunity, depth robustness, and spatial resolution. The results collectively demonstrate that the framework can reconstruct targets with a high accuracy, stability and versatility.Significance. The proposed framework has high accuracy and robustness, as well as good generalizability. Compared with traditional regularization-based reconstruction methods, it eliminates the need to manually delineate feasible regions and adjust regularization parameters. Compared with emerging deep learning assisted methods, it does not require any training dataset, thus saving a lot of time and resources and solving the problem of poor generalization and robustness of deep learning methods. Thus, the framework opens up a new perspective for the reconstruction of three-dimension optical imaging.

Near-Infrared Perylenecarboximide Fluorophores for Live-Cell Super-Resolution Imaging

Organic near-infrared (NIR) photoblinking fluorophores are highly desirable for live-cell super-resolution imaging based on single-molecule localization microscopy (SMLM). Herein we introduce a novel small chromophore, PMIP, through the fusion of perylenecarboximide with 2,2-dimetheylpyrimidine. PMIP exhibits an emission maximum at 732 nm with a high fluorescence quantum yield of 60% in the wavelength range of 700-1000 nm and excellent photoblinking without any additives. With resorcinol-functionalized PMIP (PMIP-OH), NIR SMLM imaging of lysosomes is demonstrated for the first time in living mammalian cells under physiological conditions. Moreover, metabolically labeled nascent DNA is site-specifically detected using azido-functionalized PMIP (PMIP-N3) via click chemistry, thereby enabling the super-resolution imaging of nascent DNA in phosphate-buffered saline with a 9-fold improvement in spatial resolution. These results indicate the potential of PMIP-based NIR blinking fluorophores for biological applications of SMLM.

Bioorthogonal Labeling Enables In Situ Fluorescence Imaging of Expressed Gas Vesicle Nanostructures

Gas vesicles (GVs) are proteinaceous nanostructures that, along with virus-like particles, encapsulins, nanocages, and other macromolecular assemblies, are being developed for potential biomedical applications. To facilitate such development, it would be valuable to characterize these nanostructures' subcellular assembly and localization. However, traditional fluorescent protein fusions are not tolerated by GVs' primary constituent protein, making optical microscopy a challenge. Here, we introduce a method for fluorescently visualizing intracellular GVs using the bioorthogonal label FlAsH, which becomes fluorescent upon reaction with the six-amino acid tetracysteine (TC) tag. We engineered the GV subunit protein, GvpA, to display the TC tag and showed that GVs bearing TC-tagged GvpA can be successfully assembled and fluorescently visualized in HEK 293T cells. Importantly, this was achieved by replacing only a fraction of GvpA with the tagged version. We used fluorescence images of the tagged GVs to study the GV size and distance distributions within these cells. This bioorthogonal and fractional labeling approach will enable research to provide a greater understanding of GVs and could be adapted to similar proteinaceous nanostructures.

High resolution fluorescence imaging of the alveolar scaffold as a novel tool to assess lung injury

Acute lung injury (ALI) represents an aetiologically diverse form of pulmonary damage. Part of the assessment and diagnosis of ALI depends on skilled observer-based scoring of brightfield microscopy tissue sections. Although this readout is sufficient to determine gross alterations in tissue structure, its categorical scores lack the sensitivity to describe more subtle changes in lung morphology. To generate a more sensitive readout of alveolar perturbation we carried out high resolution immunofluorescence imaging on 200 μm lung vibratome sections from baseline and acutely injured porcine lung tissue, stained with a tomato lectin, Lycopersicon Esculentum Dylight-488. With the ability to resolve individual alveoli along with their inner and outer wall we generated continuous readouts of alveolar wall thickness and circularity. From 212 alveoli traced from 10 baseline lung samples we established normal distributions for alveolar wall thickness (27.37; 95% CI [26.48:28.26]) and circularity (0.8609; 95% CI [0.8482:0.8667]) in healthy tissue. Compared to acutely injured lung tissue baseline tissue exhibited a significantly lower wall thickness (26.86 ± 0.4998 vs 50.55 ± 4.468; p = 0.0003) and higher degree of circularityϕ≤ (0.8783 ± 0.01965 vs 0.4133 ± 0.04366; p < 0.0001). These two components were subsequently combined into a single more sensitive variable, termed the morphological quotient (MQ), which exhibited a significant negative correlation (R2 = 0.9919, p < 0.0001) with the gold standard of observer-based scoring. Through the utilisation of advanced light imaging we show it is possible to generate sensitive continuous datasets describing fundamental morphological changes that arise in acute lung injury. These data represent valuable new analytical tools that can be used to precisely benchmark changes in alveolar morphology both in disease/injury as well as in response to treatment/therapy.

Reversible Dual Fluorescence-Lifetime Imaging of Mitochondrial GSH and Microviscosity: Real-Time Evaluation of Ferroptosis Status

Ferroptosis, as a new form of regulated cell death, is implicated in various physiological and pathological processes. Developing a single probe for an independent analysis of multiple analytes related to ferroptosis can provide more accurate information and simplify the detection procedures, but it faces great challenges. In this work, we develop a fluorescent probe for the simultaneous detection of GSH through ratiometric fluorescence response and microviscosity via a fluorescence lifetime model. Based on the reversible Michael addition reaction between GSH and unsaturated C═C bond, the probe responds reversibly to GSH with a ratiometric fluorescence variation and a fast response time (t1/2 = 4.7 s). At the same time, the probe is sensitive to environmental viscosity by changing its fluorescence lifetimes. The probe was applied to monitor the drug-induced ferroptosis process through both the classical Xc-/GSH/GPX4- and DHODH-mediated defense mechanisms. We hope that the probe will provide a useful molecular tool for the real-time live-cell imaging of GSH dynamics, which is benefit to unveiling related physiological and pathological processes.

Nanoscale engineering of gold nanostars for enhanced photoacoustic imaging

Photoacoustic (PA) imaging is a diagnostic modality that combines the high contrast resolution of optical imaging with the high tissue penetration of ultrasound. While certain endogenous chromophores can be visualized via PA imaging, many diagnostic assessments require the administration of external probes. Anisotropic gold nanoparticles are particularly valued as contrast agents, since they produce strong PA signals and do not photobleach. However, the synthesis of anisotropic nanoparticles typically requires cytotoxic reagents, which can hinder their biological application. In this work, we developed new PA probes based on nanostar cores and polymeric shells. These AuNS were obtained through one-pot synthesis with biocompatible Good's buffers, and were subsequently functionalized with polyethylene glycol, chitosan or melanin, three coatings widely used in (pre)clinical research. Notably, the structural features of the nanostar cores strongly affected the PA signal. For instance, despite displaying similar sizes (i.e. 45 nm), AuNS obtained with MOPS buffer generated between 2 and 3-fold greater signal intensities in the region between 700 and 800 nm than nanostars obtained with HEPES and EPPS buffers, and up to 25-fold stronger signals than spherical gold nanoparticles. A point source analytical model demonstrated that AuNS synthesized with MOPS displayed greater absorption coefficients than the other particles, corroborating the stronger PA responses. Furthermore, the AuNS shell not only improved the biocompatibility of the nanoconstructs but also affected their performance, with melanin coating enhancing the signal more than 4-fold, due to its own PA capacity, as demonstrated by both in vitro and ex vivo imaging. Taken together, these results highlight the strengths of gold nanoconstructs as PA probes and offer insights into the design rules for the nanoengineering of new nanodiagnostic agents.

A structural optimized fluorescent probe for monitoring hydrogen sulfide in cells and zebrafish

In this work, we reported a fluorescent probe Fur-SH, a derivative of benzofuranone, which was used to detect H2S in living cells and zebrafish. Based on the three structural characteristics of the probe, the effects of different structural modifications on the optical properties of the fluorophore were compared. Then, the fluorophore Fur-OH was synthesized by modifying diethylamino group with benzofuranone as the main skeleton. With 2,4-dinitrofluorobenzene as the recognition group and diethylamino as the electron donor, the push-pull electron effect occurred with nitro group, which led to fluorescence quenching, and an openable fluorescent probe Fur-SH was formed. The probe Fur-SH (λex = 510 nm; λem = 570 nm) had the advantages of smaller full width at half maxima, rapid response (5 min) and wide pH window. The quantitative properties of the probe were excellent, reaching saturation at 50 equivalents of substrate. The probe Fur-SH showed high sensitivity to H2S, with LOD of 48.9 nM and LOQ of 50 nM. At present, the probe Fur-SH had been applied to fluorescence imaging of MCF-7 cells and zebrafish. By comparing the effects of different structures on the optical properties of fluorophores, this work was expected to be helpful to the development of fluorescent probes in the future.

Ratiometric fluorescent biosensor for detection and real-time imaging of nitric oxide in mitochondria of living cells

Nitric oxide (NO), a ubiquitous gaseous messenger, plays critical roles in various pathological and physiological progresses. The abnormal levels of NO in organisms are closely related to a large number of maladies. Mitochondria are the main area that produce NO in mammalian cells. Thus, detecting and real-time imaging of NO in mitochondria is of great significance for exploring the biological functions of NO. Herein, a ratiometric fluorescent biosensor (Mito-GNP-pNO520) is developed for sensitive and selective detection and real-time imaging of NO in mitochondria of living cells. The detection is achieved through the fluorescence off-on response of Mito-GNP-pNO520 toward NO. This biosensor shows excellent characteristics, such as high sensitivity toward NO with a low detection limit of 0.25 nM, exclusive selectivity to NO without interference from other substances, good biological stability and low cytotoxicity. More importantly, the biosensor is specifically located in mitochondria, enabling the detection and real-time imaging of endogenous and exogenous NO in mitochondria of living cells. Therefore, our biosensor offers a new approach for dynamic detecting and real-time imaging of NO in subcellular organelles, providing an opportunity to explore new biological effects of NO.

Construction of a super large Stokes shift near-infrared fluorescent probe for detection and imaging of superoxide anion in living cells, zebrafish and mice

As one of the major reactive oxygen species (ROS), superoxide anion (O2•-) is engaged in maintaining redox homeostasis in the cell microenvironment. To identify the pathological roles in related disorders caused by abnormal expression of O2•-, it is of great significance to monitor and track the fluctuation of O2•- concentration in vivo. However, the low concentration of O2•- and the interference caused by tissue autofluorescence make the development of an ideal detection methodology full of challenges. Herein, a "Turn-On" chemical response near-infrared (NIR) fluorescence probe Dcm-Cu-OTf for O2•- detection in inflamed models, was constructed by conjugating the NIR fluorophore (dicyanisophorone derivative) with an O2•- sensing moiety (trifluoromethanesulfonate). Dcm-Cu-OTf exerted about 140-fold fluorescence enhancement after reacting 200 μM O2•- with an excellent limited of detection (LOD) as low as 149 nM. Additionally, Dcm-Cu-OTf exhibited a super large Stokes shift (260 nm) and high selectivity over other bio-analytes in stimulated conditions. Importantly, Dcm-Cu-OTf showed low toxicity and enabled imaging of the generation of O2•- in the Lipopolysaccharide (LPS)-stimulated HeLa cells, zebrafish, and LPS-induced inflamed mice. The present study provided a potential and reliable detection tool to inspect the physiological and pathological progress of O2•- in living biosystems.

Tumor Microenvironment-Regulating Two-Photon Probe Based on Bimetallic Post-Coordinated MOF Facilitating the Dual-Modal and Deep Imaging-Guided Synergistic Therapies

The intricate tumor microenvironment (TME) always brings about unsatisfactory therapeutic effects for treatments, although nanomedicines have been demonstrated to be highly beneficial for synergistic therapies to avoid the side effects caused by the complexity and heterogeneity of cancer. Developing nanotheranostics with the functionalities of both synergistic therapies and TME regulation is a good strategy but is still in its infancy. Herein, an "all-in-one" nanoplatform for integrated diagnosis and treatment, namely, Carrier@ICG@DOX@FA (CIDF), is constructed. Benefiting from the bimetallic coordination of Eu3+-HTHA (4,4,4-trifluoro-1-(9-hexylcarbazol-3-yl)-1,3-butanedione) and Fe3+ with the ligands in UiO-67, CIDF can simultaneously achieve two-photon fluorescence imaging, fluorescent lifetime imaging in deep tumors, and regulation of TME. Owing to its porosity, CIDF can encapsulate indocyanine green as photosensitizers and doxorubicin as chemotherapeutic agent, further realizing light-controlled drug release. Moreover, CIDF exhibited good biocompatibility and tumor targeting by coating with folic-acid-modified polymers. Both in vitro and in vivo experiments demonstrate the excellent therapeutic efficacy of CIDF through dual-modal-imaging-guided synergistic photothermal-, photodynamic-, and chemotherapy. CIDF provides a new paradigm for the construction of TME-regulated synergistic nanotheranostics and realizes the complete elimination of tumors without recurrence.

Renal-clearable nanoprobes for optical imaging and early diagnosis of diseases

Optical imaging has played an indispensable role in clinical diagnostics and fundamental biomedical research due to its high sensitivity, high spatiotemporal resolution, cost-effectiveness, and easy accessibility. However, the issues of light scattering and low tissue penetration make them effective only for superficial imaging. To overcome these issues, renal-clearable optical nanoprobes have recently emerged, which are activated by abnormal disease-associated biomarkers and initiate a pharmacokinetic switch by undergoing degradation and eventually releasing signal reporters into urine, for simple imaging and sensitive optical in vitro urinalysis. In this review, we focus on the advancements of renal-clearable organic nanoprobes for optical imaging and remote urinalysis. The versatile design strategies of these nanoprobes are discussed along with their sensing mechanisms toward biomolecules of interest as well as their unique biological applications. Finally, challenges and perspectives are discussed to further advance the next-generation renal-clearable nanoprobes for in vivo imaging and in vitro urinalysis.

Biocompatible Folic-Acid-Strengthened Ag-Ir Quantum Dot Nanozyme for Cell and Plant Root Imaging of Cysteine/Stress and Multichannel Monitoring of Hg2+ and Dopamine

To boost the enzyme-like activity, biological compatibility, and antiaggregation effect of noble-metal-based nanozymes, folic-acid-strengthened Ag-Ir quantum dots (FA@Ag-Ir QDs) were developed. Not only did FA@Ag-Ir QDs exhibit excellent synergistic-enhancement peroxidase-like activity, high stability, and low toxicity, but they could also promote the lateral root propagation of Arabidopsis thaliana. Especially, ultratrace cysteine or Hg2+ could exclusively strengthen or deteriorate the inherent fluorescence property with an obvious "turn-on" or "turn-off" effect, and dopamine could alter the peroxidase-like activity with a clear hypochromic effect from blue to colorless. Under optimized conditions, FA@Ag-Ir QDs were successfully applied for the turn-on fluorescence imaging of cysteine or the stress response in cells and plant roots, the turn-off fluorescence monitoring of toxic Hg2+, or the visual detection of dopamine in aqueous, beverage, serum, or medical samples with low detection limits and satisfactory recoveries. The selective recognition mechanisms for FA@Ag-Ir QDs toward cysteine, Hg2+, and dopamine were illustrated. This work will offer insights into constructing some efficient nanozyme sensors for multichannel environmental analyses, especially for the prediagnosis of cysteine-related diseases or stress responses in organisms.

A Self-Sustaining Near-Infrared Afterglow Chemiluminophore for High-Contrast Activatable Imaging

Afterglow imaging holds great promise for ultrasensitive bioimaging due to its elimination of autofluorescence. Self-sustaining afterglow molecules (SAMs), which enable all-in-one photon sensitization, chemical defect formation and afterglow generation, possess a simplified, reproducible, and efficient superiority over commonly used multi-component systems. However, there is a lack of SAMs, particularly those with much brighter near-infrared (NIR) emission and structural flexibility for building high-contrast activatable imaging probes. To address these issues, this study for the first time reports a methylene blue derivative-based self-sustaining afterglow agent (SAN-M) with brighter NIR afterglow chemiluminescence peaking at 710 nm. By leveraging the structural flexibility and tunability, an activatable nanoprobe (SAN-MO) is customized for simultaneously activatable fluoro-photoacoustic and afterglow imaging of peroxynitrite (ONOO- ), notably with a superior activation ratio of 4523 in the afterglow mode, which is at least an order of magnitude higher than other reported activatable afterglow systems. By virtue of the elimination of autofluorescence and ultrahigh activation contrast, SAN-MO enables early monitoring of the LPS-induced acute inflammatory response within 30 min upon LPS stimulation and precise image-guided resection of tiny metastatic tumors, which is unattainable for fluorescence imaging.