Near-infrared Fluorescent Dye Research Articles

A novel prostate cancer-specific fluorescent probe based on extracellular vesicles targeting STEAP1 applied in fluorescence guided surgery.

Radical prostatectomy with pelvic lymph node dissection is the best treatment for intermediate- to high-risk localized prostate cancer (PCa). However, conventional white light surgery has difficulties in identifying tumor boundary and micrometastases intraoperatively. Fluorescence guided surgery (FGS) can solve the above difficulties, but lacks tumor-specific near-infrared fluorescent (NIRF) probes in PCa. STEAP1 was an ideal target in PCa treatment and imaging. Here, we constructed a PCa specific fluorescent probe based on extracellular vesicles targeting STEAP1 (AS-EVs) loaded with NIRF dye S0456 and evaluated its preclinical profiles. In vitro and in vivo studies both showed S0456@AS-EVs was safe and showed strong targeting ability to PCa in various mice xenograft models. S0456@AS-EVs could clear rapidly from blood (half-time of 4.29 h) and retain in the STEAP1 positive tumor tissues for more than 72 h with the highest tumor background ratio (TBR) of 3:1, which was superior to ICG, free S0456, ICG@Ctrl-EVs and S0456@Ctrl-EVs (p < 0.01). Finally, S0456@AS-EVs was applied in FGS on intramuscular model, and the tumors were resected under white light and fluorescence respectively. Compared with white light surgery, mice undergoing FGS had lower positive margin rate and better postoperative survival (p = 0.0342).

Mechanistic Insights into HRP-Catalyzed Oxidation of the Near-Infrared Fluorescent Dye Sulfo-cyanine 7

Mechanistic Insights into HRP-Catalyzed Oxidation of the Near-Infrared Fluorescent Dye Sulfo-cyanine 7

Cancer-targeted pro-theranostic bi-metallic organo-coordination nanoparticles.

Rationale: Cancer remains a leading cause of mortality, with aggressive, treatment-resistant tumors posing significant challenges. Current combination therapies and imaging approaches often fail due to disparate pharmacokinetics and difficulties correlating drug delivery with therapeutic response. Methods: In this study, we developed radionuclide-activatable theranostic nanoparticles (NPs) comprising folate receptor-targeted bimetallic organo-nanoparticles (Gd-Ti-FA-TA NPs). Polyvalent tannic acid was used to coordinate titanium (Ti), a reactive oxygen species (ROS)-generating catalyst, gadolinium (Gd), a magnetic resonance imaging (MRI) contrast agent, and cypate, a near-infrared fluorescent dye. Results: The NPs exhibited higher magnetic field-dependent relaxivities (r 1 = 20.8 mM⁻¹s⁻¹, r 2 = 72.1 mM⁻¹s⁻¹) than Gd-DTPA (r 1 = 4.8 mM⁻¹s⁻¹, r 2 = 4.9 mM⁻¹s⁻¹) on a 3 T MRI scanner. Tannic acid coordination reduced the Ti band gap from 3.3 eV in TiO₂ NPs to 2.0 eV, tripling ROS generation under UV light exposure. In breast cancer models (4T1 and PyMT-Bo1), Cerenkov radiating radiopharmaceuticals activated Gd-Ti-FA-TA NPs in vitro and in vivo, generating cytotoxic ROS to inhibit tumor cell viability and prevent tumor progression. In vivo, the NPs selectively accumulated in 4T1 tumors and enhanced both T1 and T2 MRI contrast, highlighting a strategy to locally activate cytotoxic ROS generation with radiopharmaceuticals for cancer treatment, utilizing cross-modality PET/MRI and optical imaging for shallow and deep tissue visualization. Conclusion: The integrated nanoplatform allows direct imaging of drug delivery, providing guidance for the optimal timeline to activate therapeutic effects of pro-theranostic NPs via external triggers such as radionuclide-stimulated dynamic treatment.

A Three-In-One Heptamethine Cyanine Dye Induces Endoplasmic Reticulum Stress and Apoptosis in Colorectal Cancer.

One of the most significant challenges for image-guided cancer-targeted therapy is to develop multifunctional optical contrast agents enabling simultaneous targeting and therapy. Herein, a feasible strategy is based on the incorporation of therapeutic moieties into the non-delocalized structure of polymethine indocyanines, known as the "structure-inherent targeting" concept. By possessing a rigid chloro-cyclohexenyl ring in the heptamethine cyanine backbone, a new type of multifunctional near-infrared fluorescent dye, Ph790H, that targets tumor without the need for additional targeting ligands is synthesized. Armed with a phthalimide pharmacophore holding a prominent position in medicinal chemistry, Ph790H simultaneously induces endoplasmic reticulum (ER) stress to exert targeted therapeutic effects on HT-29 colorectal cancer xenografts. In terms of molecular mechanism, the lipophilic cationic Ph790H can be actively internalized into HT-29 cells through clathrin-mediated endocytosis. Consequently, mitochondrial reactive oxygen species (ROS) overproduction further induces activation of ER stress, demonstrated by increased ROS concentration and decreased mitochondrial membrane potential, which contributes to cell apoptosis and inhibition of tumor growth. Overall, Ph790H represents an effective "three-in-one" agent for the integration of cancer targeting, imaging, and therapy, which may provide a practical strategy to develop multifunctional small molecule theranostic agents for simultaneous cancer diagnosis and therapy.

Application of indocyanine green–human serum albumin complex in fluorescence image-guided laparoscopic anatomical liver resection: study protocol for a randomized controlled trial

BackgroundIndocyanine green (ICG) is a near-infrared fluorescent dye widely used for intraoperative navigation during liver surgeries because of its non-radioactive nature, high safety, and minimal impact on liver function. However, variability in its dosage and concentration and its low imaging success rates have limited its widespread application. To address these issues, we developed a novel ICG–human serum albumin (ICG-HSA) complex to enhance fluorescence visualization during laparoscopic anatomical liver resection.MethodsThis prospective, double-blind, single-center, randomized controlled trial will compare the fluorescence navigation effects of the novel ICG-HSA complex with the guideline-recommended ICG administration scheme. The study will involve patients aged 18 to 75 years with malignant liver tumors. The participants will undergo evaluations at specified time points, and data will be collected using an internet-based electronic data capture system. The primary outcome will be the effectiveness of intraoperative fluorescence imaging, assessed by three independent experts. The secondary outcomes will be conversion to open surgery, the total operative time, intraoperative blood loss, and long-term survival rates.DiscussionThe aim of using this novel ICG-HSA complex will be to improve the success rate of fluorescence navigation in liver resection by ensuring better stability and a longer liver retention time compared with free ICG. This study seeks to validate the clinical value of ICG-HSA in enhancing surgical precision and outcomes, ultimately promoting its broader clinical application. The results are expected to provide high-level evidence supporting the safety and efficacy of this new fluorescence imaging agent.Trial registrationClinicalTrial.gov NCT06219096. Registered on 1 December 2024.

A Phthalimide-Functionalized Heptamethine Cyanine Dye for Tumor-Targeted Photothermal Therapy.

A phthalimide-functionalized heptamethine cyanine dye, named Ph790H, is used for targeted photothermal cancer therapy in vivo. We highlight that the chemical structure of Ph790H is newly designed and synthesized for the first time in this study. By possessing a rigid chloro-cyclohexenyl ring in the heptamethine cyanine backbone, the bifunctional near-infrared (NIR) fluorescent dye Ph790H can be preferentially accumulated in tumor without the need for additional targeting ligands, which is defined as the "structure-inherent tumor targeting" concept. The phototherapeutic effect of Ph790H is evaluated in HT-29 human colorectal cancer xenografts to be used as a cancer-targeting photothermal agent. The results reveal that the Ph790H shows enhanced tumor accumulation in HT-29 xenografts 48 h post-injection with a high tumor-to-background ratio. After determination of the optimal timing for photothermal therapy (PTT), the HT-29 tumor-possessing nude mice pretreated with Ph790H are subsequently irradiated with an 808 nm NIR laser for 5 min. The tumor-targeted PTT treatment can efficiently inhibit the tumor development compared with that of control groups. Moreover, no tumor regrowth or Ph790H-induced mortality occurs after the treatment of Ph790H and laser irradiation during a period of monitoring. Therefore, this work demonstrates that the bifunctional phototheranostic agent Ph790H can be utilized for targeted cancer imaging and fluorescence-guided phototherapy simultaneously.

Computational Study of Drug Delivery Systems with Radionuclide and Fluorescence Imaging Modalities. I. Albumin-Based Systems for Doxorubicin Delivery

Molecular docking and molecular dynamics methodologies were employed to design and evaluate delivery systems for the antineoplastic agent doxorubicin (DOX) utilizing human serum albumin (HSA) as the carrier. To engineer a drug delivery system (DDS) with dual imaging modalities, complexes of the radionuclide technetium-99m (TCC) and near-infrared (NIR) fluorescent dyes, including indocyanine green (IG), methylene blue (MB), heptamethine cyanine dye AK7-5, and squaraine dye SQ1, were integrated into the protein nanocarriers. The highest binding affinities to the proteins were identified for TCC [99mTc]Tc-diisopropyl iminodiacetic acid (TcDIS), [99mTc]Tc-hydrazinonicotinic acid-H6F (TcHYN), [99mTc]Tc-Mebrofenin (TcMEB), as well as the fluorescent dyes IG and SQ1. Molecular docking analyses revealed that most technetium complexes (TCCs) bind to HSA domain I, with some exceptions showing affinity for domains I and III or domain III alone. Ternary and quaternary protein-ligand systems were explored using multiple ligand docking approaches. In ternary systems, DOX binding sites were identified either in domain I or in a region spanning multiple domains, depending on potential overlap with TCC binding sites. For quaternary systems incorporating NIR fluorophores, binding affinities decreased in the order: IG &gt; SQ1 &gt; AK7-5 &gt; MB. Molecular dynamics simulations of HSA-DOX-MB and HSA-DOX-IG complexes demonstrated stable associations between the components, with consistent center-of-mass distances and minimal perturbation of HSA structure. These findings support the potential of HSA as a suitable carrier for developing dual-modality imaging nanocarriers incorporating both radionuclide and fluorescence imaging capabilities.

Fully Bioactive Nanodrugs: Stem Cell-Derived Exosomes Engineered with Biomacromolecules to Treat CCl4- and Extreme Hepatectomy-Induced Acute Liver Failure.

Acute liver failure (ALF) is a serious global disease characterized by rapid onset and high mortality. Currently, the clinical treatment of ALF faces considerable hurdles due to limited medication options and the scarcity of liver transplants. Despite biomacromolecules such as hepatocyte growth factor (HGF) and glutathione (GSH) having been applied for ALF symptom relief in the clinic, they still face substantial challenges including poor stability, difficulty in acting on intracellular targets, and inadequate therapeutic outcome. In this work, by taking advantage of the innate targeting and regenerative capabilities of mesenchymal stem cells (MSCs), we harnessed MSC-derived exosomes as natural bioactive carriers for the simultaneous delivery of HGF and GSH, forming a fully bioactive nanodrug termed HG@Exo. Impressively, the HG@Exo demonstrated potent therapeutic effects against both carbon tetrachloride (CCl4)- and extreme hepatectomy-induced ALF through multiple mechanisms, including regulation of oxidative stress, reduction of inflammation, and promotion of hepatocyte regeneration, which were facilitated by its inflammation-targeting to damaged liver tissues. Furthermore, an FDA-approved near-infrared fluorescent dye, indocyanine green (ICG), has been incorporated into the exosomes (HGI@Exo) to endow them with real-time in vivo tracking capability, which showed favorable liver accumulation of the HGI@Exo in both CCl4- and surgery-induced ALF animal models, providing crucial insights into their biodistribution and therapeutic efficacy. Overall, the presented fully bioactive nanodrugs with targeting and theranostic abilities hold significant promise for potentiating the therapeutic efficacy of biomacromolecules for the improved treatment of ALF and other inflammatory diseases.

Nanoparticle-enhanced near-infrared fluorescence probes as a new frontier in cancer imaging

Recent advancements in nanotechnology have significantly enhanced the development of near-infrared fluorescence (NIRF) probes, positioning them as powerful tools in cancer imaging. This paper explores the unique advantages of nanoparticles incorporating NIR dyes, such as indocyanine green (ICG) and DiR, which exhibit deep tissue penetration and minimal background autofluorescence. The enhanced permeability and retention (EPR) effect facilitates selective accumulation in tumor tissues, enabling sophisticated imaging and precision-targeted drug delivery systems. This review highlights the remarkable potential of NIRF imaging techniques in molecular diagnostics, emphasizing their ability to differentiate malignant tissues at a molecular level. Additionally, we discuss various NIRF dye classifications, including cyanine and BODIPY-based probes, along with the development of multifunctional agents that enhance imaging specificity and therapeutic effectiveness. The integration of advanced targeting capabilities, including the use of antibodies and small molecules, further improves the precision of these imaging agents. While challenges remain regarding the pharmacokinetics and potential toxicity of nanoparticle-based probes, their capacity for real-time tumor tracking and the promise of multimodal imaging approaches underscore their transformative role in cancer diagnostics and treatment. By advancing the field of theranostics, nanoparticle-enhanced NIRF probes pave the way for personalized medicine and improved patient outcomes in oncology.

Albumin-seeking near-infrared-II probe evaluating blood–brain barrier disruption in stroke

BackgroundBlood-brain barrier (BBB) disruption after stroke is closely associated with brain tissue edema and neuronal injury, which requires accurate assessment. However, there is a lack of appropriate BBB imaging modality in vivo. As albumin in the blood could cross the damaged BBB into brain tissue after stroke, it serves as a biomarker for BBB disruption. Therefore, we aimed to develop an albumin-seeking near-infrared (NIR) probe to assess BBB disruption in stroke.ResultsWe proposed a chemoselective strategy for seeking albumin with NIR dyes and identified an optimal probe to evaluate BBB disruption in stroke. The probe combined a NIR fluorescent dye with inherent albumin-targeting moieties and exhibited high affinity and selectivity for binding to albumin. Using a mouse stroke model, the probe displayed a high-resolution visualization of the location and extent of BBB disruption in vivo and correlated well with BBB leakage measured by Evans blue ex vivo. A dual-channel NIR-II imaging was successfully used to simultaneously assess BBB disruption and cerebral perfusion after stroke. Furthermore, we applied this method to dynamically evaluate the BBB disruption process and reperfusion of thrombolytic therapy in a stroke model in real time, which showed excellent application value.ConclusionsWe developed an albumin-seeking NIR probe that accurately evaluated BBB disruption in a safe, non-invasive and real-time manner in various stroke models, and has a great potential guiding stroke treatment in a real-time manner.Graphical

Production, Characterization, and Application of Hydrophobin-Based IR780 Nanoparticles for Targeted Photothermal Cancer Therapy and Advanced Near-Infrared Imaging.

As a promising approach for breast cancer treatment, photothermal therapy (PTT) features high spatial selectivity, noninvasiveness, and minimal drug resistance. IR780 (a near-infrared fluorescent dye) serves as an effective photosensitizer in PTT cancer therapy. However, the clinical application of IR780 in PTT has been hindered by its poor water solubility and unstable photostability. In this study, a genetically engineered dual-functional fusion protein tLyP-1-MGF6 is successfully constructed and expressed, which presents a novel use of hydrophobin MGF6 for its amphiphilicity combined with the tumor-penetrating peptide tLyP-1 to create an innovative carrier for IR780. These results show this fusion protein serving as a biodegradable and biocompatible carrier, significantly improves the water solubility of IR780 when formulated into nanoparticles. These studies demonstrate that the IR780@tLyP-1-MGF6 nanoparticles significantly enhance tumor targeting and photothermal therapeutic efficacy in comparison with control in vitro and in vivo. These advancements highlight the potential of the unique combination hydrophobin-based IR780 delivery system as a multifunctional nanoplatform for integrated imaging and targeted photothermal treatment of breast cancer.

Synthesis and evaluation of a novel BODIPY fluorescent probe targeting integrin αvβ3 for cancer diagnosis

A series of integrin αvβ3 targeting BODIPY-RGD conjugate were designed and synthesized. Their in vitro and in vivo fluorescence imaging behaviors were investigated. The small molecule compound was designed as an optical imaging near-infrared fluorescent dye which was combined RGD peptide with the meso-amide BODIPYs using succinic moiety as a spacer. The construction alleviated the traditional BODIPY problems including poor water solubility, aggregate caused quench (ACQ) effect, low biocompatibility, etc. In cellular research, BDP-RGD-2 showed rapid, selective uptake in 3 highly expressing integrin αvβ3 cell lines MDA-MB-231, A549, U87MG at different extent rather than an integrin αvβ3 low level expression cell MCF-7. In animal study, fluorescence imaging of U87MG model targeted by BDP-RGD-2 displayed a highest tumor uptake level and T/N ratio up to 6 h after tail-intravenous injection, which demonstrated BDP-RGD-2 was a promising probe for tracing integrin αvβ3 overexpressing tumors.

A novel NIR-activatable and photodegradable mitochondria-targeted nano-photosensitizer for superior photodynamic therapy

Photodynamic therapy (PDT) has garnered significant interest as a promising approach for cancer treatment due to its effectiveness, versatility, and non-invasiveness. However, its clinical application is hindered by several factors, such as suboptimal efficacy, poor targeting capabilities, shallow penetration depth, and safety concerns. Herein, we introduce B-SQ, a novel nano-photosensitizer that addresses these challenges. B-SQ is a self-assembling, cancer mitochondria-targeting agent that is both activatable and photodegradable, designed by strategically modifying a near-infrared fluorescent squaraine dye. We extensively assessed the PDT potential of B-SQ in various cancer cell models and explored the molecular mechanisms of PDT-induced cell death. Importantly, B-SQ demonstrated high specificity for cancer cells, and its PDT efficiency was activatable, with near-infrared fluorescence to distinguish cancer cells from normal cells. This work provides the first evidence of B-SQ inducing the intrinsic mitochondrial apoptosis pathway and cell cycle arresting in cancer cells via PDT. Additionally, its photodegradable nature is likely to minimize side effects after treatment. This research introduces an innovative class of nano-photosensitizers that are activatable, targeting cancer mitochondria, and are photodegradable with near-infrared fluorescence. These qualities present new possibilities for safer and more effective clinical cancer treatments in the future.

Evaluation of a targeted anti-αvβ3 integrin near-infrared fluorescent dye for fluorescence-guided resection of naturally occurring soft tissue sarcomas in dogs

PurposeComplete resection is a key prognostic factor for survival in patients with soft tissue sarcoma (STS), in humas and companion animals alike. Fluorescence-guided surgery could improve resection accuracy. As dogs are frequently affected by STS, they serve as a model to test an anti-αvβ3 integrin targeting near-infrared fluorescent (NIRF) dye (AngiostampTM800) for fluorescence-guided surgery in STS to evaluate its safety and feasibility in dogs, and if it translates into a clinically relevant benefit compared to the standard of care with regards to completeness of surgery and local recurrence. Furthermore, we aimed to correlate target expression and NIRF-signal intensity.MethodsTwenty dogs with STS were randomly allocated to either receive Angiostamp™ (NIRF group) or physiologic saline (control group) preoperatively. The researchers were blinded for treatment, and resections were adapted based on the NIRF-signal, if needed. Margin status was histologically determined at the 1 and 3 cm margin. The tumor-to-background ratio was measured in native tissue biopsies and formalin-fixed tissue. The fluorescent area was compared to the corresponding tumor areas as confirmed by histology using the Dice coefficient. Target expression was quantified by immunohistochemistry and correlated to NIRF-signal ratios.ResultsA fluorescent signal was detected in all 10 tumors of the NIRF group, with a tumor-to-background ratio of 7.4 ± 5.8 in native biopsies and 13.5 ± 10.9 in formalin-fixed tissue. In the NIRF group, resection margins were adapted in 5/10 cases, leading to complete resection and preventing R1 in four of these cases. In the NIRF and control group 9/10 and 8/10 resections were R0, with one local recurrence in each group and one sarcoma-related death in the NIRF group. The NIRF-signal correlated with the histologically confirmed tumor area (Dice coefficient 0.75 ± 0.17). Target expression was higher in tumor compared to peritumoral tissue (p < 0.0003) and showed a moderate correlation with the NIRF-signal (r = 0.6516, p < 0.0001).ConclusionFluorescence-guided surgery using Angiostamp™ can pinpoint residual disease in the tumor bed and contributes to an improved resection accuracy in canine STS.

Structural Engineering of Cationic Block Copolymer Architectures for Selective Breaching of Prokaryotic and Eukaryotic Biological Species.

Positively charged antimicrobial polymers are known to cause severe damage to biological systems, and thus synthetic strategies are urgently required to design next-generation nontoxic cationic macromolecular architectures for healthcare applications. Here, we report a structural-engineering strategy to build cationic linear and star-block copolymer nanoarchitectures having identical chemical composition, molar mass, nanoparticle size, and positive surface charge, yet they differ distinctly in their biological action in breaching prokaryotic species such as E. coli (Gram-negative bacteria) without affecting eukaryotic species like red-blood and mammalian cells. For this purpose, linear and star-block structures are built on a polycaprolactone biodegradable platform having an imidazolium positive handle. Under physiological conditions, the linear architecture exhibits toxicity indiscriminately to all biological species, whereas its star counterpart is remarkably selective in membrane breaching action toward bacteria while maintaining inertness toward eukaryotic species. Confocal microscopy analysis of HPTS fluorescent dye-loaded star-polymer nanoparticles substantiated their antimicrobial action in E. coli. Tissue-penetrable near-infrared fluorescent dye (IR-780) loaded NP aided the in vivo biodistribution analysis and ex vivo quantification of cationic species' accumulations in vital organs in mice. Azithromycin, a clinical water-insoluble macrolide, is delivered from the star platform to accomplish synergistic antimicrobial activity by the combination of bactericidal-bacteriostatic action of the polymer carrier and drug together in a single system.

Pre-clinical study of IR808 dye for cervical cancer in vitro and in vivo imaging.

There is an urgent need for improved methods for early screening and rapid diagnosis of cervical cancer since current conventional screening methods are plagued by operator subjectivity and unnecessary biopsies. IR808 is a tumour-targeting near-infrared (NIR) fluorescent dye that permits NIR imaging without the requirement of chemical conjugation. Our study investigates an IR808-based strategy for real-time monitoring of the cervix in vivo and rapid assessment of cervical specimens in vitro. We investigated the uptake of IR808 in vitro using normal cervical epithelial cells and three cervical cancer cell lines. The biodistribution of IR808 was examined in vivo via intravenous injection into tumour-bearing mice. Additionally, in vitro tissues were stained with IR808 to simulate the identification of cervical tumors in the clinical setting. Biocompatibility of the dye in both cellular and animal models was also examined. IR808 exhibited significant tumour-to-background ratios in fluorescence molecular imaging of in vivo tumors in nude mice. The application of NIR fluorescent dye IR808 in specific imaging screening, safe and non-invasive real-time monitoring, and rapid identification of cervical tumors from tissue specimens is expected to improve current screening methods for cervical cancer.

Micelle-encapsulated IR783 for enhanced photothermal therapy in mouse breast cancer

BackgroundPhotothermal therapy, an emerging cancer treatment, selectively eliminates lesions using photothermal compounds that convert light into heat. IR783, a near-infrared fluorescent heptamethine cyanine dye, has been used to achieve selective hyperthermic effects in target tissues via near-infrared irradiation. To implement IR783 as a photothermal agent, IR783 biodistribution must be calibrated to achieve a constant and uniform concentration in target cells. Accordingly, we developed micelle-encapsulated IR783 (IR783 micelles) and evaluated their effectiveness as photothermal drugs. MethodsIn vitro, the photothermic effects of free IR783 and IR783 micelle solutions induced by near-infrared light irradiation were analyzed. Additionally, we investigated the mechanism of cell death mediated by photothermal therapy using free IR783 and IR783 micelles in mouse breast cancer (EMT6) cells. In vivo, the efficacy of photothermal therapy with both free IR783 and IR783 micelles was examined in EMT6-bearing mice. ResultsIn vitro, the temperature of free and micelle-encapsulated IR783 solutions increased after near-infrared irradiation. Near-infrared irradiation with free IR783 and IR783 micelles induced cytotoxicity in cancer cells by generating heat. In vivo, IR783 micelles elicited more preferential tumor tissue uptake and enhanced the antitumor effects of photothermal therapy at a lower light dose relative to free IR783. ConclusionsOverall, these results suggest that IR783 micelles could accumulate in mouse breast cancer tissues and exhibit enhanced antitumor effects when used as a photothermal therapy, with superior effects obtained at 2.1 W/cm2 (252 J/cm2) compared with that of free IR783.

Incorporation of pre- and intra-operative sentinel lymph node mapping techniques in dogs with apocrine gland anal sac adenocarcinoma

The high incidence of nodal metastasis, variable lymphatic drainage patterns, and prognostic significance of nodal metastasis in dogs with apocrine gland anal sac adenocarcinoma (AGASACA) highlight the need for development of standardized techniques for lymph node staging in canine AGASACA. The aim of this study was to develop and describe the utility of pre- and intra-operative sentinel lymph node (SLN) mapping techniques for subsequent nodal extirpation and histologic assessment in dogs with AGASACA. A prospective clinical trial was performed as a pilot study. Eight client-owned dogs with unilateral AGASACA were enrolled. Preoperative contrast-enhanced ultrasound (CEUS) via transrectal ultrasound (TRUS) and CT-lymphography (CTL) was followed by intraoperative SLN mapping within 7 days utilizing a visible dye (methylene blue [MB]) and a near-infrared (NIR) fluorescent dye (indocyanine green [ICG]) with subsequent nodal extirpation and routine anal sacculectomy. In all dogs, preoperative CTL and intraoperative SLN mapping identified at least one SLN. Pre- and intra-operative findings differed in 4/8 dogs. Preoperative CEUS identified a SLN in 7/8 dogs, but the exact location of the SLN was indeterminate. Extirpated lymph nodes were metastatic in 2/8 dogs. Preoperative CTL and intraoperative MB and ICG were an effective combination of SLN mapping techniques in dogs with AGASACA. These techniques each provided unique advantages. Combined, they identified and guided extirpation of early metastatic lymph nodes. Large-scale, prospective studies utilizing the techniques described are needed to accurately determine the incidence and significance of early/occult nodal metastasis in canine AGASACA.

An intelligent NIR fluorescent dye with dual response to pH and viscosity for investigating the interactions between LDs and mitochondria

The interaction between lipid droplets and mitochondria plays a pivotal role in biological processes including cellular stress, metabolic homeostasis, cellular autophagy and apoptosis. Deciphering the complex interplay between lipid droplets and mitochondria is essential for gaining insights into the fundamental workings of the cell and can have broad implications for the development of therapeutic strategies for various diseases, including metabolic disorders, neurodegenerative diseases, and cancer. In this study, we develop a pH and viscosity-responsive near-infrared (NIR) fluorescent probe PTOH to investigate the interaction between lipid droplets and mitochondria. This probe demonstrates a significant enhancement in fluorescence intensity at 470 nm when the pH increases, while under acidic conditions, its fluorescence intensity at 730 nm intensifies by a factor of 35 with rising system viscosity. Cell imaging experiments revealed that PTOH can effectively discriminate between normal and cancerous cells, as well as detect intracellular pH and viscosity alterations induced by drugs. Additionally, PTOH is utilized to visualize the interaction between lipid droplets and mitochondria and to differentiate between cellular autophagy and apoptosis phenomena, providing a valuable tool for elucidating the mechanisms underlying lipid droplet-mitochondria interactions and their associated diseases.

Collagen-targeted protein nanomicelles for the imaging of non-alcoholic steatohepatitis

In vivo molecular imaging tools hold immense potential to drive transformative breakthroughs by enabling researchers to visualize cellular and molecular interactions in real-time and/or at high resolution. These advancements will facilitate a deeper understanding of fundamental biological processes and their dysregulation in disease states. Here, we develop and characterize a self-assembling protein nanomicelle called collagen type I binding – thermoresponsive assembled protein (Col1-TRAP) that binds tightly to type I collagen in vitro with nanomolar affinity. For ex vivo visualization, Col1-TRAP is labeled with a near-infrared fluorescent dye (NIR-Col1-TRAP). Both Col1-TRAP and NIR-Col1-TRAP display approximately a 3.8-fold greater binding to type I collagen compared to TRAP when measured by surface plasmon resonance (SPR). We present a proof-of-concept study using NIR-Col1-TRAP to detect fibrotic type I collagen deposition ex vivo in the livers of mice with non-alcoholic steatohepatitis (NASH). We show that NIR-Col1-TRAP demonstrates significantly decreased plasma recirculation time as well as increased liver accumulation in the NASH mice compared to mice without disease over 4 hours. As a result, NIR-Col1-TRAP shows potential as an imaging probe for NASH with in vivo targeting performance after injection in mice. Statement of significanceDirect molecular imaging of fibrosis in NASH patients enables the diagnosis and monitoring of disease progression with greater specificity and resolution than do elastography-based methods or blood tests. In addition, protein-based imaging probes are more advantageous than alternatives due to their biodegradability and scalable biosynthesis. With the aid of computational modeling, we have designed a self-assembled protein micelle that binds to fibrillar and monomeric collagen in vitro. After the protein was labeled with near-infrared fluorescent dye, we injected the compound into mice fed on a NASH diet. NIR-Col1-TRAP clears from the serum faster in these mice compared to control mice, and accumulates significantly more in fibrotic livers.This work advances the development of targeted protein probes for in vivo fibrosis imaging.