Near-infrared Fluorescence Research Articles

NIR fluorescence of phenol-π-malononitrile derivatives achieved by extending π-bridge and unexpected intermolecular deprotonation

NIR fluorescent phenol-π-malononitrile derivatives were achieved by extending vinylene π-bridge through Wittig reaction and following Knoevenagel condensation. In addition to regular D-A effect, unexpected intermolecular deprotonation of phenol group triggered by an electron-withdrawing group on phenyl ring pushed emissions to 762 nm with a large Stokes shift up to 323 nm. The extending of π-bridge and unexpected intermolecular deprotonation of phenol group promised a feasible strategy for construction of low-molecular weight NIR fluorophores.

A pan-cancer dye for solid-tumour screening, resection and wound monitoring via short-wave and near-infrared fluorescence imaging.

The efficacy of fluorescence-guided surgery in facilitating the real-time delineation of tumours depends on the optical contrast of tumour tissue over healthy tissue. Here we show that CJ215-a commercially available, renally cleared carbocyanine dye sensitive to apoptosis, and with an absorption and emission spectra suitable for near-infrared fluorescence imaging (wavelengths of 650-900 nm) and shortwave infrared (SWIR) fluorescence imaging (900-1,700 nm)-can facilitate fluorescence-guided tumour screening, tumour resection and the assessment of wound healing. In tumour models of either murine or human-derived breast, prostate and colon cancers and of fibrosarcoma, and in a model of intraperitoneal carcinomatosis, imaging of CJ215 with ambient light allowed for the delineation of nearly all tumours within 24 h after intravenous injection of the dye, which was minimally taken up by healthy organs. At later timepoints, CJ215 provided tumour-to-muscle contrast ratios up to 100 and tumour-to-liver contrast ratios up to 18. SWIR fluorescence imaging with the dye also allowed for quantifiable non-contact wound monitoring through commercial bandages. CJ215 may be compatible with existing and emerging clinical solutions.

ImmunoPET imaging of EpCAM in solid tumours with nanobody tracers: a preclinical study.

Epithelial cell adhesion molecule (EpCAM) is a potential therapeutic target and anchoring molecule for circulating and disseminated tumour cells (CTC/DTC) in liquid biopsy. In this study, we aimed to construct EpCAM-specific immuno-positron emission tomography (immunoPET) imaging probes and assess the diagnostic abilities in preclinical cancer models. By engineering six single-domain antibodies (e.g., EPCD1 - 6) targeting EpCAM of different binding properties and labelling with 68Ga (T1/2 = 1.1 h) and 18F (T1/2 = 110 min), we developed a series of EpCAM-targeted immunoPET imaging probes. The probes' pharmacokinetics and diagnostic accuracies were investigated in cell-derived human colorectal (LS174T) and esophageal cancer (OE19) tumour models. Based on in vitro binding affinities and in vivo pharmacokinetics of the first three tracers ([68Ga]Ga-NOTA-EPCD1, [68Ga]Ga-NOTA-EPCD2, and [68Ga]Ga-NOTA-EPCD3), we selected [68Ga]Ga-NOTA-EPCD3 for tumour imaging which showed an average tumour uptake of 2.06 ± 0.124%ID/g (n = 3) in LS174T cell-derived tumour model. Development and characterisation of [18F]AIF-RESCA-EPCD3 showed comparable tumour uptake of 1.73 ± 0.0471%ID/g (n = 3) in the same tumour model. Further validation of [68Ga]Ga-NOTA-EPCD3 in OE19 cell-derived tumour model showed an average tumour uptake of 4.27 ± 1.16%ID/g and liver uptake of 13.5 ± 1.30%ID/g (n = 3). Near-infrared fluorescence imaging with Cy7-EPCD3 confirmed the in vivo pharmacokinetics and relatively high liver accumulation. We further synthesized another three 18F-labeled nanobody tracers ([18F]AIF-RESCA-EPCD4, [18F]AIF-RESCA-EPCD5, and [18F]AIF-RESCA-EPCD6) and found that [18F]AIF-RESCA-EPCD6 had the best pharmacokinetics with low background. [18F]AIF-RESCA-EPCD6 showed explicit uptake in the subcutaneously inoculated OE19 tumour model with an average uptake of 4.70 ± 0.26%ID/g (n = 3). In comparison, the corresponding tumour uptake (0.17 ± 0.25%ID/g, n = 3) in the EPCD6 blocking group was substantially lower (P < 0.001), indicating the targeting specificity of the tracer. We developed a series of 68Ga/18F-labeled nanobody tracers targeting human EpCAM. ImmunoPET imaging with [18F]AIF-RESCA-EPCD6 may facilitate better use of EpCAM-targeted therapeutics by noninvasively displaying the target's expression dynamics.

PEGylate engineering for preparing water-soluble deep/near-infrared red type I/II photosensitizer and its efficient photodynamic therapy of cancer cells

Photodynamic therapy has still received more research attention because of its significant advantages of minimally invasive, high selectivity and non-drug-resistance. Photosensitizer is one of important compositions in the photodynamic therapy process, which could be divided into two categories of containing energy transfer dominant process (type II) and electron transfer dominant process (type I) from triplet state to oxygen. Usually, type I photosensitizers have the merit of low oxygen dependence, leading them to become a popular and important candidate for treating cancers because there is hypoxic environment in the solid tumor. However, poor water solubility and short emissive wavelength of reported type I photosensitizer make them suffer certain limitation in clinical application. Hence, it is urgent to develop water-soluble near-infrared red type I photosensitizer. Herein, choosing classical biocompatible macromolecule of polyethylene glycol to modify the designed ionic type I photosensitizer with aggregation-induced near-infrared red fluorescence to prepare a new water-soluble polymeric type I/II photosensitizer (named as PEG-MTPABZ-PyC). PEG-MTPABZ-PyC displays remarkable water solubility (37 µg/mL), and maximal fluorescent wavelength peaks at 670 nm and extends to 850 nm of tail of fluorescent spectrum in aqueous solution, which endows it better efficiency of labelling cells by the significant red fluorescence. Additionally, its superior type I/II reactive oxygen species provide better killing of cancer cells in vitro. This study provides an effective method to prepare water-soluble near-infrared red type I/II photosensitizer, which exhibits satisfactory photophysical property and biocompatibility as well as excellent efficiency for killing cancer cells under normoxia and hypoxia, offering great potential for clinical disease treatment.

Advances in Modern Microsurgery.

Background/Objectives: Microsurgery employs techniques requiring optical magnification and specialized instruments to operate on small anatomical structures, including small vessels. These methods are integral to plastic surgery, enabling procedures such as free tissue transfer, nerve reconstruction, replantation, and lymphatic surgery. This paper explores the historical development, advancements, and current applications of microsurgery in plastic surgery. Methods: The databases MEDLINE (via PubMed) and Web of Science were selectively searched with the term "(((microsurgery) OR (advances)) OR (robotic)) OR (AI)) AND (((lymphatic surgery) OR (peripheral nerve surgery)) OR (allotransplantation))" and manually checked for relevance. Additionally, a supplementary search among the references of all publications included was performed. Articles were included that were published in English or German up to June 2024. Results: Modern microsurgical techniques have revolutionized plastic surgery, enabling precise tissue transfers, improved nerve reconstruction, and effective lymphedema treatments. The evolution of robotic-assisted surgery, with systems like da Vinci and MUSA, has enhanced precision and reduced operative times. Innovations in imaging, such as magnetic resonance (MR) lymphography and near-infrared fluorescence, have significantly improved surgical planning and outcomes. Conclusions: The continuous advancements in microsurgery, including supermicrosurgical techniques and robotic assistance, have significantly enhanced the capabilities and outcomes of plastic surgery. Future developments in AI and robotics promise further improvements in precision and efficiency, while new imaging modalities and surgical techniques expand the scope and success of microsurgical interventions.

Near-Infrared Fluorescent Probe Reveals Elevated Mitochondrial Viscosity during Acute Alcoholic Liver Injury.

Acute alcoholic liver injury (AALI) has become an important cause of liver disease worldwide, and there is an urgent need to develop noninvasive and sensitive methods to detect and evaluate AALI. We report herein three novel but readily available mitochondrial targeting fluorescence probes (ICR, ICJ, and ICQ) for AALI detection. These probes contain different electron-donating groups, among which ICQ exhibits NIR fluorescence (740 nm), a large Stokes shift (110 nm), and a sensitive response to viscosity (73-fold enhancement in fluorescence from water to glycerol), making it suitable for in vivo imaging. ICQ also exhibits an excellent ability to image mitochondrial viscosity changes in cells. More importantly, ICQ can target the liver selectively and image the viscosity changes in the liver noninvasively. Through establishing an AALI mouse model, ICQ was successfully applied to the in situ imaging changes in liver viscosity during the AALI process. The results showed a significant increase in liver viscosity in AALI mice, indicating that viscosity can serve as a marker for AALI, and ICQ is a promising noninvasive and sensitive tool for detecting and evaluating AALI.

Recent Advancement of Indocyanine Green Based Nanotheranostics for Imaging and Therapy of Coronary Atherosclerosis.

Atherosclerosis is a vascular intima condition in which any part of the circulatory system is affected, including the aorta and coronary arteries. Indocyanine green (ICG), a theranostic compound approved by the FDA, has shown promise in the treatment of coronary atherosclerosis after incorporation into nanoplatforms. By integration of ICG with targeting agents such as peptides or antibodies, it is feasible to increase its concentration in damaged arteries, hence increasing atherosclerosis detection. Nanotheranostics offers cutting-edge techniques for the clinical diagnosis and therapy of atherosclerotic plaques. Combining the optical properties of ICG with those of nanocarriers enables the improved imaging of atherosclerotic plaques and targeted therapeutic interventions. Several ICG-based nanotheranostics platforms have been developed such as polymeric nanoparticles, iron oxide nanoparticles, biomimetic systems, liposomes, peptide-based systems, etc. Theranostics for atherosclerosis diagnosis use magnetic resonance imaging (MRI), computed tomography (CT), near-infrared fluorescence (NIRF) imaging, photoacoustic/ultrasound imaging, positron emission tomography (PET), and single photon emission computed tomography (SPECT) imaging techniques. In addition to imaging, there is growing interest in employing ICG to treat atherosclerosis. In this review, we provide a conceptual explanation of ICG-based nanotheranostics for the imaging and therapy of coronary atherosclerosis. Moreover, advancements in imaging modalities such as MRI, CT, PET, SPECT, and ultrasound/photoacoustic have been discussed. Furthermore, we highlight the applications of ICG for coronary atherosclerosis.

Parathyroid gland identification and angiography classification using simple machine learning methods.

Near-infrared indocyanine green angiography allows experienced surgeons to reliably evaluate parathyroid gland vitality during thyroid and parathyroid operations in order to predict postoperative function. To facilitate equal performance between surgeons, we developed an automatic computational quantification method using computer vision that portrays expert interpretation of visualized parathyroid gland near-infrared indocyanine green angiographic fluorescence signals. Near-infrared indocyanine green-parathyroid gland angiography video recordings (Fluobeam® LX, Fluoptics, Grenoble-part of Getinge-Göteborg) from patients undergoing endocrine cervical surgery in a high-volume unit were used for model development. Computation (MATLAB, Mathworks, Ireland) included segmentation-identification of the parathyroid gland (by autofluorescence), image stabilization (by linear translation) and adjusted time-fluorescence intensity profile generation. Relative upslope and maximum intensity ratios then trained a simple logistic regression model based on expert interpretation and outcome (including hypoparathyroidism), with subsequent unseen testing for validation. The model was trained on 37 patient videos (45 glands, 29 judged well perfused by parathyroid gland angiography experts), achieving feature data separation with 100% accuracy, and tested on 22 unseen videos (27 glands, 15 judged well perfused), including four in real time. Segmentation-guided parathyroid gland detection correctly identified all parathyroid glands during unseen testing along with three additional non-parathyroid gland regions (90% positive predictive value). Subsequent time-fluorescence intensity profile extraction with vitality prediction was shown feasible in all cases within 5 min, with a 96.3% model accuracy (sensitivity and specificity were 93.3 and 100% respectively) when compared with expert judgement. Automatic parathyroid gland perfusion quantification using simple machine learning computational methods discriminates parathyroid gland perfusion in concordance with expert surgeon interpretation, providing a means for near-infrared indocyanine green-parathyroid gland signal evaluation.

Alkyl-Doping Enables Significant Suppression of Conformational Relaxation and Intermolecular Nonradiative Decay for Improved Near-Infrared Fluorescence Imaging.

Despite various efforts to optimize the near-infrared (NIR) performance of perylene diimide (PDI) derivatives for bio-imaging, convenient and efficient strategies to amplify the fluorescence of PDI derivatives in biological environment and the intrinsic mechanism studies are still lacking. Herein, we propose an alkyl-doping strategy to amplify the fluorescence of PDI derivative-based nanoparticles for improved NIR fluorescence imaging. The developed PDI derivative, OPE-PDI, shows much brighter in n-Hexane (HE) compared with that in other organic media, and the excited state dynamics investigation experimentally elucidates the solvent effect-induced suppression of intermolecular energy transfer and intramolecular nonradiative decay as the underlying mechanism for the fluorescence improvement. Theoretical calculations reveal the lowest reorganization energies of OPE-PDI in HE among various solvents, indicating the effectively suppressed conformational relaxation to support the strongest radiative decay. Inspired by this, an alkyl atmosphere mimicking HE is constructed by incorporating the octadecane into OPE-PDI-based nanoparticles, permitting up to 3-fold fluorescence improvement compared with the counterpart nanoparticles. Owing to the merits of high brightness, anti-photobleaching, and low biotoxicity for the optimal nanoparticles, they have been employed for probing and long-term monitoring of tumor. This work highlights a facile strategy for the fluorescence enhancement of PDI derivative-based nanoparticles.

Interstitial Optical Fiber-Mediated Multimodal Phototheranostics Based on an Aggregation-Induced NIR-II Emission Luminogen for Orthotopic Breast Cancer Treatment.

One-for-all phototheranostics based on a single molecule is recognized as a convenient approach for cancer treatment, whose efficacy relies on precise lesion localization through multimodal imaging, coupled with the efficient exertion of phototherapy. To unleash the full potential of phototheranostics, advancement in both phototheranostic agents and light delivery methods is essential. Herein, an integrated strategy combining a versatile molecule featuring aggregation-induced emission, namely tBuTTBD, with a modified optical fiber to realize comprehensive tumor diagnosis and "inside-out" irradiation in the orthotopic breast tumor, is proposed for the first time. Attributed to the intense donor-acceptor interaction, highly distorted conformation, abundant molecular rotors, and loose intermolecular packing upon aggregation, tBuTTBD can synchronously undergo second near-infrared (NIR-II) fluorescence emission, photothermal and photodynamic generation under laser irradiation, contributing to a trimodal NIR-II fluorescence-photoacoustic (PA)-photothermal imaging-guided phototherapy. The tumor treatment is further carried out following the insertion of a modified optical fiber, which is fabricated by splicing a flat-end fiber with an air-core fiber. This configuration aims to enable effective in situ phototherapy by maximizing energy utilization for therapeutic benefits. This work not only enriches the palette of NIR-II phototheranostic agents but also provides valuable insight for exploring an integrated phototheranostic protocol for practical cancer treatment.

Visible light-triggered NIR ratiometric fluorescent metal-free CO-releasing molecule for self-monitoring of CO delivery and effective cancer therapy

Cancer is a serious global health issue, and exploring effective treatment methods is of great significance for cancer prevention and control. Carbon monoxide (CO), as an important gas signaling molecule in the life system, has been proven to have good anti-cancer effects. However, how to controllably, safely, and effectively deliver CO to the tumor site for clinical treatment remains a challenge. Herein, a new metal-free CO-releasing molecule COR-XAC was developed for controlling CO release and cancer therapy. COR-XAC is based on the hybrid of 3-hydroxyl flavone and oxanthracene fluorophores, showing visible light-controlled CO-releasing properties and near-infrared (NIR) ratiometric fluorescence changes at 690 and 760 nm. COR-XAC shows low cytotoxicity and can be successfully applied to release CO in cells and tumors, and the CO-releasing and delivery process could be monitored by its own NIR ratiometric fluorescence changes. More importantly, the anti-cancer performance of COR-XAC was evaluated in 4T1 tumor mice, and it was found that COR-XAC plus light illumination showed excellent tumor inhibition effect, which provided a promising new effective method for cancer treatment.

Mitochondria-targeted NIR molecular probe for detecting viscosity of gland damage and SO2 in actual samples

Glandular damage can be caused by various factors, including disease, trauma, or other abnormalities within the organism. The viscosity of the gland is one of the important indicators to measure the degree of damage. Sulfur dioxide (SO2) is widely used as an important food additive due to its preservative and bleaching properties, but its overuse has serious negative impacts on the environment, so it is urgent to develop a simple detection method. Herein, we designed and synthesized a mitochondria-targeted near-infrared (NIR) fluorescence probe (BDC) for the detection of viscosity and SO2. BDC consisted of a donor-π-acceptor (D-π-A) structure and extended double bonds bridging rotor, which enabled sensitive response to viscosity and intense fluorescence emission. The TICT (twisted intramolecular charge transfer) of BDC was inhibited with an increase in viscosity, accompanied by a significant enhancement of red fluorescence signal with emission wavelength beyond 800 nm. Notably, BDC was able to noninvasively and sensitively monitor the viscosity changes in the glands of non-obese diabetic (NOD) mice model. BDC was utilized for monitoring SO2 in food and environmental samples through Michael addition reactions, providing a straightforward tool for SO2 detection in food safety and environmental monitoring.

Azaindole-based asymmetric pentamethine cyanine dye for mitochondrial pH detection and near-infrared ratiometric fluorescence imaging of mitophagy

Azaindole-based asymmetric pentamethine cyanine dye for mitochondrial pH detection and near-infrared ratiometric fluorescence imaging of mitophagy

Blood perfusion assessment by near-infrared fluorescence angiography of epiploic appendages in prevention of anastomotic leakage after laparoscopic intersphincteric resection for ultra-low rectal cancer: a case-matched study.

The role of intraoperative near-infrared fluorescence angiography with indocyanine green in reducing anastomotic leakage (AL) has been demonstrated in colorectal surgery, however, its perfusion assessment mode, and efficacy in reducing anastomotic leakage after laparoscopic intersphincteric resection (LsISR) need to be further elucidated. Aim was to study near-infrared fluorescent angiography to help identify bowel ischemia to reduce AL after LsISR. A retrospective case-matched study was conducted in one referral center. A total of 556 consecutive patients with ultra-low rectal cancer including 140 patients with fluorescence angiography of epiploic appendages (FAEA)were enrolled. Perfusion assessment by FAEA in the monochrome fluorescence mode. Patients were divided into two groups based on perfusion assessment by FAEA. The primary endpoint was the AL rate within 6 months, and the secondary endpoint was the structural sequelae of anastomotic leakage (SSAL). After matching, the study group (n = 109) and control group (n = 190) were well-balanced. The AL rate in the FAEA group was lower before (3.6% vs. 10.1%, P = 0.026) and after matching (3.7% vs. 10.5%, P = 0.036). Propensity scores matching analysis (OR 0.275, 95% CI 0.035-0.937, P 0.039), inverse probability of treatment weighting (OR 0.814, 95% CI 0.765-0.921, P 0.002), and regression analysis (OR 0.298, 95% CI 0.112-0.790, P = 0.015), showed that FAEA was an independent protector factor for AL. This technique can significantly shorten postoperative hospital stay [9 (6-13) vs. 10 (8-13), P = 0.024] and reduce the risk of SSAL (1.4% vs. 6.0%, P = 0.029). Perfusion assessment by FAEA can achieve better visualization in LsISR and reduce the incidence of AL, subsequently avoiding SSAL after LsISR.

504. SENTINEL LYMPH NODE NAVIGATED SURGERY IN ESOPHAGOGASTRIC JUNCTION ADENOCARCINOMA USING INDOCYANINE GREEN AND FLUORESCENCE IMAGING

Abstract Background Sentinel lymph node navigated surgery (SNNS) has been adopted for various cancers to reduce the negative impact of lymphadenectomy. Limited lymph node dissection using SNNS might be employed in the management of clinically lymph node negative early esophagogastric junction adenocarcinoma (EGJAC). However, it must be sure that sentinel lymph nodes (SLNs) reflect the patient's overall pN status. The aim of this study was to determine the feasibility and safety of SNNS using near-infrared fluorescence imaging and to obtain preliminary data about sensitivity of prediction of lymph node metastasis using SNNS. Methods Patients with cT1-2cN0 EGJAC without neoadjuvant therapy were prospectively included. One patient was enrolled after non-radical endoscopic resection of a high-risk pT1 tumor. Solution of indocyanine green (ICG) and 10% human serum albumin (ICG concentration 1,25mg/mL) was injected endoscopically into the submucosal layer at four quadrants (á 0.5mL) around the tumor or endoscopic resection scar just before the surgery. Subsequently, SLNs were identified and removed laparoscopically using fluorescence imaging. Then, esophagectomy or gastrectomy with radical lymphadenectomy were performed in all patients. Results A total of nine patients underwent SNNS followed by radical surgery. Histopathology revealed pT0pN0 in 1 patient, pT1bN0 in 3 patients, pT1bN3 in 1 patient, pT2pN1 in 2 patients, pT3pN0 in 1 patient and pT3pN2 in 1 patient. Overall, 62 SLNs were detected (median 7 SLNs per patient, range 1-16). Metastases in SLNs were found in four patients. All patients with pathologically positive lymph nodes had at least one SLN positive for metastasis. Sensitivity of prediction of pN positive status was 100%, false negative rate was 0%. There were no ICG-related adverse events or complications associated with SNNS procedure. Conclusion These results suggest that SNNS using ICG and fluorescence imaging in early EGJAC is feasible and safe. Our pilot data show promising diagnostic accuracy of predicting pathological lymph node status using SNNS. However, further studies with a larger number of patients are needed before introducing SNNS into clinical practice.

Dual-Modal Near-Infrared Organic Nanoparticles: Integrating Mild Hyperthermia Phototherapy with Fluorescence Imaging.

Our study seeks to develop dual-modal organic-nanoagents for cancer therapy and real-time fluorescence imaging, followed by their pre-clinical evaluation on a murine model. Integrating NIR molecular imaging with nanotechnology, our aim is to improve outcomes for early-stage cutaneous melanoma by offering more effective and less invasive methods. This approach has the potential to enhance both photothermal therapy (PTT) and Sentinel Lymph Node Biopsy (SLNB) procedures for melanoma patients. NIR-797-isothiocyanate was encapsulated in poly(D,L-lactide-co-glycolide) acid (PLGA) nanoparticles (NPs) using a two-step protocol, followed by thorough characterization, including assessing loading efficiency, fluorescence stability, and photothermal conversion. Biocompatibility and cellular uptake were tested in vitro on melanoma cells, while PTT assay, with real-time thermal monitoring, was performed in vivo on tumor-bearing mice under irradiation with an 808 nm laser. Finally, ex vivo fluorescence microscopy, histopathological assay, and TEM imaging were performed. Our PLGA NPs, with a diameter of 270 nm, negative charge, and 60% NIR-797 loading efficiency, demonstrated excellent stability and fluorescence properties, as well as efficient light-to-heat conversion. In vitro studies confirmed their biocompatibility and cellular internalization. In vivo experiments demonstrated their efficacy as photothermal agents, inducing mild hyperthermia with temperatures reaching up to 43.8 °C. Ex vivo microscopy of tumor tissue confirmed persistent NIR fluorescence and uniform distribution of the NPs. Histopathological and TEM assays revealed early apoptosis, immune cell response, ultrastructural damage, and intracellular material debris resulting from combined NP treatment and irradiation. Additionally, TEM analyses of irradiated zone margins showed attenuated cellular damage, highlighting the precision and effectiveness of our targeted treatment approach. Specifically tailored for dual-modal NIR functionality, our NPs offer a novel approach in cancer PTT and real-time fluorescence monitoring, signaling a promising avenue toward clinical translation.

Enhanced tumor targeting and penetration of fluorophores via iRGD peptide conjugation: a strategy for the precision targeting of lung cancer.

Accurate real-time tumor delineation is essential for achieving curative resection (R0 resection) during non-small cell lung cancer (NSCLC) surgery. The unique characteristics of lung tissue structure significantly challenge the use of video-assisted thoracoscopic surgery in the identification of lung nodules. This difficulty often results in an inability to discern the margins of lung nodules, necessitating either an expansion of the resection scope, or a transition to open surgery. Due to its high spatial resolution, ease of operation, and capacity for real-time observation, near-infrared fluorescence (NIRF) navigation in oncological surgery has emerged as a focal point of clinical research. Targeted NIRF probes, which accumulate preferentially in tumor tissues and are rapidly cleared from normal tissues, enhance diagnostic sensitivity and surgical outcomes. The imaging effect of the clinically approved NIRF probe indocyanine green (ICG) varies significantly from person to person. Therefore, we hope to develop a new generation of targeted NIRF probes targeting lung tumor-specific targets. First, the peptide iRGD (sequence: CRGDKGPDC) fluorescent tracer was synthesized, and characterized through mass spectrometry (MS), proton nuclear magnetic resonance (1H NMR), and high-performance liquid chromatography (HPLC). Fluorescence properties were tested subsequently. Safety was performed in vitro using both human normal liver cells and human normal breast cells. Second, Metabolism and optimal imaging time were determined by tail vein injection of iRGD fluorescent tracer. Finally, Orthotopic and metastatic lung tumor models were used to evaluate the targeting properties of the iRGD fluorescent tracer. We successfully synthesized an iRGD fluorescent tracer specifically designed to target NSCLC. The molecular docking analyses indicated that this tracer has receptor affinity comparable to that of iRGD for αvβ3 integrin, with a purity ≥98%. Additionally, the tracer is highly soluble in water, and its excitation and emission wavelengths are 767 and 799 nm, respectively, positioning it within the near-infrared spectrum. The cellular assays confirmed the tracer's minimal cytotoxicity, underscoring its excellent biosafety profile. In vivo studies further validated the tracer's capacity for specific NSCLC detection at the cellular level, alongside a prolonged imaging window of 6 days or more. Notably, the tracer demonstrated superior specificity in localizing very small lung nodules, which are otherwise clinically indiscernible, outperforming non-targeted ICG. Fluorescence intensity analyses across various organs revealed that the tracer is predominantly metabolized by the liver and kidneys, with excretion via bile and urine, and exhibits minimal toxicity to these organs as well as the lungs. The iRGD fluorescent tracer selectively accumulates in NSCLC tissues by specifically targeting αvβ3 receptors, which are overexpressed on the surface of tumor cells. This targeted approach facilitates the real-time intraoperative localization of NSCLC, presenting an improved strategy for intraoperative tumor identification with significant potential for clinical application.

Intravascular ICG-enhanced NIRF-IVUS imaging to assess progressive atherosclerotic lesions in excised human coronary arteries

Indocyanine green (ICG)-enhanced intravascular near-infrared fluorescence (NIRF) imaging enhances the information obtained with intravascular ultrasound (IVUS) by visualizing pathobiological characteristics of atherosclerotic plaques. To advance our understanding of this hybrid method, we aimed to assess the potential of NIRF-IVUS to identify different stages of atheroma progression by characterizing ICG uptake in human pathological specimens. After excision, 15 human coronary specimens from 13 adult patients were ICG-perfused and imaged with NIRF-IVUS. All specimens were then histopathologically and immunohistochemically assessed. NIRF-IVUS imaging revealed colocalization of ICG-deposition to plaque areas of lipid accumulation, endothelial disruption, neovascularization and inflammation. Moreover, ICG concentrations were significantly higher in advanced coronary artery disease stages (p < 0.05) and correlated significantly to plaque macrophage burden (r = 0.67). Current intravascular methods fail to detect plaque biology. Thus, we demonstrate how human coronary atheroma stage can be assessed based on pathobiological characteristics uniquely captured by ICG-enhanced intravascular NIRF.

Monitoring cysteine changes and assessing ferroptosis in diabetic mice with a lysosome-targeted near-infrared fluorescence probe

Diabetes, characterized by elevated blood sugar levels, often leads to various complications. Cysteine (Cys), a biomarker of oxidative stress, is crucial in the progression of diabetes and its complications. Unfortunately, up until now, fluorescent probes for imaging lysosomal Cys in diabetic mouse models have not been available. Ferroptosis, linked to antioxidant damage in the lysosomal Cys/GPX4 axis, plays a significant role in diabetes. Visualizing lysosomal Cys is vital for assessing ferroptosis and understanding diabetes. We introduce a new near-infrared (NIR) fluorescent probe, NIR-Lys-Cys, designed to detect lysosomal Cys in living cells and diabetic mouse models. This probe shows exceptional selectivity and sensitivity towards Cys, along with superior fluorescence characteristics, enabling detection of Cys in living cells. NIR-Lys-Cys can monitor ferroptosis and its inhibition by measuring lysosomal Cys levels and has been used to detect ferroptosis in glucose-induced diabetic cells. It revealed significantly lower Cys concentrations in the livers of diabetic mice compared to healthy controls. Administering antidiabetic medication increased Cys production in diabetic mice. These findings highlight the potential of NIR-Lys-Cys as a tool for elucidating the role of Cys in lysosome-related diseases, providing critical insights into diagnosis and treatment strategies for diabetes and its complications.

Activatable near-infrared fluorescence probe for real-time imaging of PD-L1 expression in tumors.

In clinical practice, determining programmed death-ligand 1 (PD-L1) expression is crucial for selecting patients and monitoring immune checkpoint blockade therapies. Currently, PD-L1 expression is quantified using immunohistochemistry (IHC). However, IHC-based methods do not capture the heterogeneous and dynamic nature of PD-L1 expression. Thus, there is a pressing need for a rapid and efficient method for monitoring PD-L1 expression both in vitro and in vivo, which would considerably aid in prognosis and treatment selection. In this study, we present for the first time an activatable near-infrared (NIR) fluorescence imaging probe (Q-Atezol) for the real-time monitoring of PD-L1 expression in vitro and in vivo. The ability of Q-Atezol to detect PD-L1 expression quickly and in real-time was evaluated in both tumor spheroid and lung cancer xenograft models. An always-on optical probe (ON-Atezol) was synthesized and tested for comparison. In vivo NIR fluorescence imaging studies were conducted on A549 and H1975 tumor-bearing mice, and their tumor-to-background ratios (TBRs) were analyzed. The quenched NIR fluorescence of Q-Atezol is activated upon binding to PD-L1 proteins on the surface of cancer cells, thereby enabling PD-L1 detection in the three-dimensional (3D) tumor spheroids without a washing step. Notably, PD-L1-positive H1975 tumors were clearly visualized with a high TBR 6 hours after Q-Atezol injection, whereas ON-Atezol treatment could not detect H1975 tumors even 24 hours post-injection. The activatable fluorescence probe Q-Atezol demonstrated great potential as an exceptional sensor for assessing PD-L1 expression in 3D cell structures and for in vivo applications.