Multispectral Fluorescence Imaging Research Articles

Magnesium microspheres to enhance lipiodol-mediated transarterial chemo-embolization (TACE) of hepatocellular carcinoma: From bench to a pilot clinical study.

e16204 Background: Transarterial chemoembolization (TACE) has been extensively used in clinic to treat unresectable hepatocellular carcinoma (HCC). However, arterial embolization would worsen the hostile physicochemical features in the tumor microenvironment (TME) by further reducing its pH and increasing hypoxia, leading to immunosuppressive TME and drug resistance. Methods: Magnesium microspheres (Mg MSs), acting as H2 donors and pH modulators, were prepared via gas atomization pulverization. Characterization included inverted optical microscopy, SEM, and XRD analysis. Their H2 generation and acid neutralization capabilities were confirmed. The Lip-Mg dispersion (Mg MSs dispersed in lipiodol) was tested for therapeutic efficacy in H22 murine liver tumor-bearing mice, 4T1, and CT26 subcutaneous tumor models, as well as in vivo interventional TAE therapy for rabbit orthotopic liver tumors. The modulated capacities of Lip-Mg in H2 gas generation, acid neutralization, and promotion of antitumor immune response were investigated in vivo. Finally, a single-center, single-arm, open-label trial (ChiCTR2200064999) evaluated the safety and efficacy of TACE treatment with Lip-Mg (M-TACE) in Chinese HCC patients. Results: Inverted optical microscopy and SEM images confirmed uniform, smooth Mg microspheres (~60 μm) with a grayish-white color. In acidic buffer (pH 6.4), Mg microspheres rapidly increased pH, as measured by pH meter or fluorescent probe. Lip-Mg treatment significantly inhibited tumor growth compared to controls, prolonging mouse survival by ~2-fold, validated in 4T1 and CT26 models. Ultrasonic and multispectral fluorescence imaging demonstrated Lip-Mg's ability to release H2 and neutralize pH in vivo, reversing the immunosuppressive tumor microenvironment. Clinical study showed manageable treatment-related adverse events, with no unexpected toxicities and negligible impact on serum magnesium levels, confirming the safety of Mg microspheres for M-TACE. According to mRECIST, M-TACE exhibited high CR (61.5%), PR (38.5%), and ORR (100%) rates, with an overall response rate and CR rate of 90% and 60%, respectively. Conclusions: Metallic Mg microspheres (~60 μm) were developed to enhance lipiodol-mediated TAE/TACE for HCC. When combined with lipiodol and injected, they neutralized the acidic TME, triggered hydrogen therapy, and reversed immunosuppression, effectively inhibiting tumor growth. Lip-Mg showed superior outcomes to lipiodol alone for TAE therapy, with M-TACE treatment exhibiting higher ORR and CR rates than cTACE. Post-M-TACE, adverse events were managed well without treatment discontinuations. Our study introduces Mg microspheres as a promising embolic device for M-TACE therapy, potentially improving TACE benefits. Clinical trial information: ChiCTR2100050327.

Roadmap to a large area multispectral fluorescence imaging system

Roadmap to a large area multispectral fluorescence imaging system

Ultra-photostable small-molecule dyes facilitate near-infrared biophotonics

Long-wavelength, near-infrared small-molecule dyes are attractive in biophotonics. Conventionally, they rely on expanded aromatic structures for redshift, which comes at the cost of application performance such as photostability, cell permeability, and functionality. Here, we report a ground-state antiaromatic strategy and showcase the concise synthesis of 14 cationic aminofluorene dyes with mini structures (molecular weights: 299–504 Da) and distinct spectra covering 700–1600 nm. Aminofluorene dyes are cell-permeable and achieve rapid renal clearance via a simple 44 Da carboxylation. This accelerates optical diagnostics of renal injury by 50 min compared to existing macromolecular approaches. We develop a compact molecular sensing platform for in vivo intracellular sensing, and demonstrate the versatile applications of these dyes in multispectral fluorescence and optoacoustic imaging. We find that aromaticity reversal upon electronic excitation, as indicated by magnetic descriptors, not only reduces the energy bandgap but also induces strong vibronic coupling, resulting in ultrafast excited-state dynamics and unparalleled photostability. These results support the argument for ground-state antiaromaticity as a useful design rule of dye development, enabling performances essential for modern biophotonics.

Polysuccinimide-based nanoparticle: A nanocarrier with drug release delay and zero burst release properties for effective theranostics of cancer

We have developed a novel pH-responsive delivery system consisting of oleylamine-modified polysuccinimide (PSI) nanoparticles (NPs) whereby NPs remained stable and started to release bioactive agents after 8.5 h with maximal release acquired after 36 h under physiological pH. Our NPs did not exhibit any burst release of drug, which is a key advantage in anti-cancer targeted drug delivery system. Here, the NPs function as a carrier for bioactive agents such as Curcumin and IR-780 dye whereby the former exerts its intrinsic anti-cancer abilities, the latter confers photothermal treatment application and bimodal imaging ability using photoacoustic and fluorescence imaging. In vitro and in vivo results establish that administration of folate receptors targeting PSI-NPs in U87MG model effected in a substantial decrease in tumour and photothermal laser exposure at 808 nm further ablated tumours to an almost total eradication. Our dual loaded targeted NPs demonstrated selectivity through enhanced accumulation and retention in tumours as indicated by multi-spectral optoacoustic tomography (MSOT) and fluorescence imaging (FI). Loading of Curcumin and IR-780 into PSI-NPs improved its bioavailability, allowing Curcumin to be administered into the circulation system and retention in tumours which led to the simultaneous application for a successful targeted, synergistic photothermal treatment and bimodal imaging using MSOT and FI.

Iterative prototyping based on lessons learned from the falloposcope in vivo pilot study experience.

High grade serous ovarian cancer is the most deadly gynecological cancer, and it is now believed that most cases originate in the fallopian tubes (FTs). Early detection of ovarian cancer could double the 5-year survival rate compared with late-stage diagnosis. Autofluorescence imaging can detect serous-origin precancerous and cancerous lesions in ex vivo FT and ovaries with good sensitivity and specificity. Multispectral fluorescence imaging (MFI) can differentiate healthy, benign, and malignant ovarian and FT tissues. Optical coherence tomography (OCT) reveals subsurface microstructural information and can distinguish normal and cancerous structure in ovaries and FTs. We developed an FT endoscope, the falloposcope, as a method for detecting ovarian cancer with MFI and OCT. The falloposcope clinical prototype was tested in a pilot study with 12 volunteers to date to evaluate the safety and feasibility of FT imaging prior to standard of care salpingectomy in normal-risk volunteers. In this manuscript, we describe the multiple modifications made to the falloposcope to enhance robustness, usability, and image quality based on lessons learned in the clinical setting. The diameter falloposcope was introduced via a minimally invasive approach through a commercially available hysteroscope and introducing a catheter. A navigation video, MFI, and OCT of human FTs were obtained. Feedback from stakeholders on image quality and procedural difficulty was obtained. The falloposcope successfully obtained images in vivo. Considerable feedback was obtained, motivating iterative improvements, including accommodating the operating room environment, modifying the hysteroscope accessories, decreasing endoscope fragility and fiber breaks, optimizing software, improving fiber bundle images, decreasing gradient-index lens stray light, optimizing the proximal imaging system, and improving the illumination. The initial clinical prototype falloposcope was able to image the FTs, and iterative prototyping has increased its robustness, functionality, and ease of use for future trials.

A starch-based implant as a controlled drug release system: Non-invasive in vivo characterization using multispectral fluorescence imaging.

Solid implants are parenteral depot systems that can provide a controlled release of drugs in the desired body area over a few days to months. Finding an alternative for the two most commonly used polymers in the production of parenteral depot systems, namely Poly-(lactic acid) (PLA) and Poly-(lactide-co-glycolide) (PLGA), is of great importance due to their certain drawbacks. Our previous study showed the general suitability of starch-based implants for controlled drug release system. In this study, the system is further characterized and the release kinetics are investigated in vitro and in vivo by fluorescence imaging (FI). ICG and DiR, two fluorescent dyes with different hydrophobicity serving as a model for hydrophilic and hydrophobic drugs, have been used. In addition to 2D FI, 3D reconstructions of the starch implant were also used to assess the release kinetics in 3D mode. The in vitro and in vivo studies showed a fast release of ICG and a sustained release of DiR over 30days from the starch-based implant. No treatment-related adverse effects were observed in mice. Our results indicate the promising potential of the biodegradable biocompatible starch-based implant for the controlled release of hydrophobic drugs.

Enhancing intraoperative tumor delineation with multispectral short-wave infrared fluorescence imaging and machine learning.

Fluorescence-guided surgery (FGS) provides specific real-time visualization of tumors, but intensity-based measurement of fluorescence is prone to errors. Multispectral imaging (MSI) in the short-wave infrared (SWIR) has the potential to improve tumor delineation by enabling machine-learning classification of pixels based on their spectral characteristics. Determine whether MSI can be applied to FGS and combined with machine learning to provide a robust method for tumor visualization. A multispectral SWIR fluorescence imaging device capable of collecting data from six spectral filters was constructed and deployed on neuroblastoma (NB) subcutaneous xenografts ( ) after the injection of a NB-specific NIR-I fluorescent probe (Dinutuximab-IRDye800). We constructed image cubes representing fluorescence collected from to 1450nm and compared the performance of seven learning-based methods for pixel-by-pixel classification, including linear discriminant analysis, -nearest neighbor classification, and a neural network. The spectra of tumor and non-tumor tissue were subtly different and conserved between individuals. In classification, a combine principal component analysis and -nearest-neighbor approach with area under curve normalization performed best, achieving 97.5% per-pixel classification accuracy (97.1%, 93.5%, and 99.2% for tumor, non-tumor tissue and background, respectively). The development of dozens of new imaging agents provides a timely opportunity for multispectral SWIR imaging to revolutionize next-generation FGS.

SUFI: an automated approach to spectral unmixing of fluorescent multiplex images captured in mouse and post-mortem human brain tissues

BackgroundMultispectral fluorescence imaging coupled with linear unmixing is a form of image data collection and analysis that allows for measuring multiple molecular signals in a single biological sample. Multiple fluorescent dyes, each measuring a unique molecule, are simultaneously measured and subsequently “unmixed” to provide a read-out for each molecular signal. This strategy allows for measuring highly multiplexed signals in a single data capture session, such as multiple proteins or RNAs in tissue slices or cultured cells, but can often result in mixed signals and bleed-through problems across dyes. Existing spectral unmixing algorithms are not optimized for challenging biological specimens such as post-mortem human brain tissue, and often require manual intervention to extract spectral signatures. We therefore developed an intuitive, automated, and flexible package called SUFI: spectral unmixing of fluorescent images.ResultsThis package unmixes multispectral fluorescence images by automating the extraction of spectral signatures using vertex component analysis, and then performs one of three unmixing algorithms derived from remote sensing. We evaluate these remote sensing algorithms’ performances on four unique biological datasets and compare the results to unmixing results obtained using ZEN Black software (Zeiss). We lastly integrate our unmixing pipeline into the computational tool dotdotdot, which is used to quantify individual RNA transcripts at single cell resolution in intact tissues and perform differential expression analysis, and thereby provide an end-to-end solution for multispectral fluorescence image analysis and quantification.ConclusionsIn summary, we provide a robust, automated pipeline to assist biologists with improved spectral unmixing of multispectral fluorescence images.

X-ray, multispectral and chlorophyll fluorescence images: innovative methods for evaluating the physiological potential of rice seeds

Abstract: Image analysis techniques are expanding in agriculture and, for being fast, simple, and not destroying samples, they are interesting alternatives in the detection of immature rice seeds. Therefore, the aim of this study was to evaluate the quality of rice seeds using X-ray, multispectral and chlorophyll fluorescence image analysis techniques. Initially, with the seeds identified and numbered, radiographic images were obtained to determine the free space (area between the endosperm + embryo and the glumes). Subsequently, with the same seeds used in the X-ray, multispectral and chlorophyll fluorescence images were acquired, and then the computerized seedling analysis was performed with the SVIS® software. It was concluded that rice seeds that do not germinate or originate abnormal seedlings have free space equal to or greater than 18.68%, higher reflectance in the spectral bands with wavelength from 590 nm to 780 nm (41.46% to 64.21%, respectively) and in the band of 970 nm (75.65%), in addition to having chlorophyll fluorescence values equal to or greater than 40.58 and 112.92 at excitation/emission energies of 630/700 nm and 645/700 nm, respectively.

Evaluation of phenotypic and photosynthetic indices to detect water stress in perennial grass species using hyperspectral, multispectral and chlorophyll fluorescence imaging

Evaluation of phenotypic and photosynthetic indices to detect water stress in perennial grass species using hyperspectral, multispectral and chlorophyll fluorescence imaging

Smartphone-Based Snapshot Fluorescence Multispectral Imaging

Smartphone-Based Snapshot Fluorescence Multispectral Imaging

Study of High-Temperature-Induced Morphological and Physiological Changes in Potato Using Nondestructive Plant Phenotyping.

Potato (Solanum tuberosum L.) is vulnerable to high temperatures, which are expected to increase in frequency and duration due to climate change. Nondestructive phenotyping techniques represent a promising technology for helping the adaptation of agriculture to climate change. In this study, three potato cultivars (Agria, Bellarosa and Desiree) were grown under four temperature treatments: 20/15 °C (T1), 25/20 °C (T2), 30/25 °C (T3), and 35/30 °C (T4). Multispectral and chlorophyll fluorescence imaging, 3D multispectral scanning, and gas exchange analysis were used to study the effect of moderate heat stress on potato morphology and physiology and select phenotypic traits most responsive to increased temperatures. The most responsive morphological traits to increased temperatures are related to decreased leaf area, which were detected already at T2. Increased temperatures (already T2) also changed leaf spectral characteristics, indicated by increased red, green, and blue reflectance and decreased far-red reflectance and anthocyanin index (ARI). Regarding chlorophyll fluorescence, increasing temperatures (T2) caused an increase in minimal fluorescence of both dark-adapted (F0) and light-adapted (F0') plants. Stomatal conductance, transpiration rate, photosynthetic rate, instantaneous water use efficiency (WUE), and intrinsic water use efficiency increased from T1 to T3 and decreased again in T4. Using recursive partitioning analysis, the most responsive potato phenotypic traits to increased temperature were leaf area projected (LAP), ARI, F0, and WUE. These traits could be considered marker traits for further studying potato responses to increased temperatures.

Abstract IA019: Molecular pathological epidemiology of tumor microbiota and immunity can give etiologic insights

Abstract This lecture discusses the integration of tumor microbiology and immunology into evolving/expanding molecular pathological epidemiology (MPE) research framework (Ogino et al. Gut 2011; Ogino et al. Annu Rev Pathol 2019; Inamura et al. Gut 2022; etc.), which will open new opportunities. Neoplasms represent heterogeneous pathological processes due to interactive influences of the exposome (including the microbiome), the immune system, and neoplastic cells. Hence cancers should be regarded as not only microenvironmental diseases but also environmental and systemic diseases (Inamura et al. Gut 2022). To address this complexity, we investigate influences of exposures on microbial-tumor-immune interactions in tumor microenvironment. Colorectal cancer (CRC) provides an ideal model, as the colorectum is the most microbial rich organ and there are many established or putative risk factors for CRC. In our proof-of-principle studies that used the Nurses’ Health Study and Health Professionals Follow-up Study along with tumor tissue biobanks having 1700 CRC cases, we can provide evidence for influences of prudent diets (Mehta et al. JAMA Oncol 2017), inflammatory diets (Liu et al. Clin Gastroenterol Hepatol 2018), and western diets (Arima et al. Gastroenterology 2022) on developments of cancer subtypes with intratumor bacteria such as Fusobacterium nucleatum and pks+ Escherichia coli. We have also gain insights into interactions between microbes and immune cells. We have discovered an inverse relationship between F. nucleatum and T cell infiltrates (Mima et al. JAMA Oncol 2015), especially CD3+CD4+CD45RO+ memory helper T cells (Borowsky et al. Clin Cancer Res 2021). In situ spatial single cell analyses using multispectral fluorescence imaging and machine learning can shed light on the roles of microbes as well as various immune cell infiltrates in CRC (Vayrynen et al. Cancer Immunol Res 2021; Vayrynen et al. J. ImmunoTher Cancer 2021; Vayrynen et al. Cancer Immunol Res 2022; Akimoto et al. Front Immunol 2022). The integrative MPE approach is also expected to advance research on early-onset cancers (Akimoto et al. Nat Rev Clin Oncol 2021; Ugai et al. Nat Rev Clin Oncol, in press). Our new research paradigm to integrate microbial and immune assays on archival tumor tissue in large-scale population studies can provide not only etiological insights but also possible paths for precision medicine and prevention. Citation Format: Shuji Ogino. Molecular pathological epidemiology of tumor microbiota and immunity can give etiologic insights [abstract]. In: Proceedings of the AACR Special Conference on Colorectal Cancer; 2022 Oct 1-4; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;82(23 Suppl_1):Abstract nr IA019.

First Clinical Investigation of Near-Infrared Window IIa/IIb Fluorescence Imaging for Precise Surgical Resection of Gliomas.

The near-infrared window II (NIR-II, 1000-1700 nm) imaging, including NIR-IIa (1300-1400 mm) and NIR-IIb (1500-1700 mm), outperforms the near-infrared window I (NIR-I, 700-900 nm) imaging in biological researches. However, the advantages of NIR-IIa/IIb imaging in human study are ambiguous. This study aims to apply the NIR-IIa/IIb imaging to glioma resection and evaluate their performance by using the developed imaging instrument and intraoperative image fusion method. A multispectral fluorescence imaging instrument that integrated NIR-I/II/IIa/IIb fluorescence imaging and an intraoperative image fusion method have been developed. Seven patients with grade III/IV glioma have been enrolled. NIR-I/II images of the tumor and NIR-I/II/IIa/IIb images of cerebral vessels were acquired with the administration of indocyanine green. Images were fused using the specialized fusion method to synchronously provide the distribution of the vessels and the surgical boundaries. The NIR-IIa/IIb imaging was successfully applied to the clinic. High imaging resolution and contrast have been attained in the NIR-IIa/IIb spectra. Besides, capillaries with an apparent diameter as small as 182 μm were acquired using NIR-IIb imaging. Tumor-feeding arteries were precisely blocked and tumors were excised to the maximum extent for all patients. The blood loss volume during surgery was significantly reduced compared with the control group. The multispectral fluorescence imaging showed high performance, which led to a significant reduction in blood loss volume. The novel multispectral fluorescence imaging technology can assist surgeons in other vascular surgeries in the future.

Clinical Response to Anti-CD47 Immunotherapy Is Associated with Rapid Reduction of Exhausted Bystander CD4+ BTLA+ T Cells in Tumor Microenvironment of Mycosis Fungoides.

Simple SummaryThe identification of the events that accompany cancer progression is essential for developing new therapies. We have used mycosis fungoides, the most common type of cutaneous lymphoma, as a model for our study. We have shown that cancer progression is accompanied by the expansion of exhausted immune cells around malignant cells. Those exhausted cells prevent immune activation, blocking cancer clearance by the immune system. Furthermore, we have demonstrated that novel anti-CD47 immunotherapy with mycosis fungoides leads to the reduction of exhausted T cells accompanied by the expansion of NK and CD8+ T cells. These therapeutic benefits of CD47 blockade were further facilitated by interferon-α, which stimulates cytotoxic cells. Thus, we showed that CD47 might serve as an effective therapeutic target in treating mycosis fungoides.Cancer progression in mycosis fungoides, the most common form of cutaneous T-cell lymphoma, occurs in a predictable, sequential pattern that starts from patches and that evolves to plaques and later to tumors. Therefore, unlocking the relationship between the microarchitecture of mycosis fungoides and the clinical counterparts of that microstructure represents important steps for the design of targeted therapies. Using multispectral fluorescent imaging, we show that the progression of mycosis fungoides from plaque to tumor parallels the cutaneous expansion of the malignant CD4+ T cells that express TOX. The density of exhausted BTLA+ CD4+ T cells around malignant CD4+TOX+ cells was higher in tumors than it was in plaques, suggesting that undesired safeguards are in place within the tumor microenvironment that prevent immune activation and subsequent cancer eradication. Overriding the CD47 checkpoint with an intralesional SIRPαFc fusion decoy receptor induced the resolution of mycosis fungoides in patients that paralleled an amplified expansion of NK and CD8+ T cells in addition to a reduction of the exhausted BTLA+ CD4+ T cells that were engaged in promiscuous intercellular interactions. These therapeutic benefits of the CD47 blockade were further unleashed by adjuvant interferon-α, which stimulates cytotoxic cells, underscoring the importance of an inflamed microenvironment in facilitating the response to immunotherapy. Collectively, these findings support CD47 as a therapeutic target in treating mycosis fungoides and demonstrate a synergistic role of interferon-α in exploiting these clinical benefits.

Handheld Multispectral Fluorescence Imaging System to Detect and Disinfect Surface Contamination.

Contamination inspection is an ongoing concern for food distributors, restaurant owners, caterers, and others who handle food. Food contamination must be prevented, and zero tolerance legal requirements and damage to the reputation of institutions or restaurants can be very costly. This paper introduces a new handheld fluorescence-based imaging system that can rapidly detect, disinfect, and document invisible organic residues and biofilms which may host pathogens. The contamination, sanitization inspection, and disinfection (CSI-D) system uses light at two fluorescence excitation wavelengths, ultraviolet C (UVC) at 275 nm and violet at 405 nm, for the detection of organic residues, including saliva and respiratory droplets. The 275 nm light is also utilized to disinfect pathogens commonly found within the contaminated residues. Efficacy testing of the neutralizing effects of the ultraviolet light was conducted for Aspergillus fumigatus, Streptococcus pneumoniae, and the influenza A virus (a fungus, a bacterium, and a virus, respectively, each commonly found in saliva and respiratory droplets). After the exposure to UVC light from the CSI-D, all three pathogens experienced deactivation (> 99.99%) in under ten seconds. Up to five-log reductions have also been shown within 10 s of UVC irradiation from the CSI-D system.

GeTe Nanosheets as Theranostic Agents for Multimodal Imaging and Therapy of Inflammatory Bowel Disease

AbstractRecently, 2D nanomaterials have received considerable attention in nanomedicine due to their intrinsic optical properties, biocompatibility, and therapeutic effect. Here, 2D germanium telluride (GeTe) nanosheets coated with polyvinylpyrrolidone (PVP) (GeTe‐PVP NSs) developed as theranostic agents are reported that can be used for multispectral optoacoustic tomography (MSOT) and fluorescence imaging and therapy of inflammatory bowel disease (IBD). GeTe‐PVP NSs, fabricated by simple sonication in ethanol and PVP, show broad optical absorption in visible and near‐infrared (NIR) ranges (400–1200 nm) and have intrinsic fluorescence properties. Thus, they provide deeper ex vivo and in vivo MSOT tissue images than gold nanorods or indocyanine green with strong optical absorption in the first NIR window (700–900 nm). In addition, when orally administered to IBD mice, GeTe‐PVP NSs exhibit therapeutic efficacy similar to or higher than sulfasalazine, with strong accumulation at inflammatory colon sites. This demonstrates that oral administration of GeTe‐PVP NSs may be used to treat inflammatory diseases in the gastrointestinal tract.

Evaluating Japanese dace (Tribolodon hakonensis) fish freshness during storage using multispectral images from visible and UV excited fluorescence

This research aimed at providing a quick, and non-destructive method for estimating freshness of intact Japanese dace (Tribolodon hakonensis) fish refrigerated below 5 °C using multispectral imaging technique coupled with multivariate analysis techniques. The fluorescence excitation-emission matrices (EEMs) for outside parts of the fish (eyeball, scales) were taken to establish the proper excitation wavelengths. Afterwards, four lighting devices; white, 395 nm, 365 nm and 280 nm LEDs were used to illuminate the sample for capturing images using both the UV camera and a common color camera. Biochemical analysis (electrophoresis measurement) was carried out to examine fish freshness and then expressed using a reference method as K values. Both EEM and imaging data were modelled with the measured K value using partial least square (PLS) regression. A novel algorithm based on multispectral imaging data was proposed as a potential fish freshness indicator during storage. From the results, R2 of 0.94 and RMSE of 2.42% were achieved. This research demonstrated that the fluorescence multispectral imaging technique is a powerful tool with great potential in non-destructive monitoring and examining fish freshness during storage.

In-vitro and in-vivo characterization of CRANAD-2 for multi-spectral optoacoustic tomography and fluorescence imaging of amyloid-beta deposits in Alzheimer mice

The abnormal deposition of fibrillar beta-amyloid (Aβ) deposits in the brain is one of the major histopathological hallmarks of Alzheimer’s disease (AD). Here, we characterized curcumin-derivative CRANAD-2 for multi-spectral optoacoustic tomography and fluorescence imaging of brain Aβ deposits in the arcAβ mouse model of AD cerebral amyloidosis. CRANAD-2 showed a specific and quantitative detection of Aβ fibrils in vitro, even in complex mixtures, and it is capable of distinguishing between monomeric and fibrillar forms of Aβ. In vivo epi-fluorescence microscopy and optoacoustic tomography after intravenous CRANAD-2 administration demonstrated higher cortical retention in arcAβ compared to non-transgenic littermate mice. Immunohistochemistry showed co-localization of CRANAD-2 and Aβ deposits in arcAβ mouse brain sections, thus verifying the specificity of the probe. In conclusion, we demonstrate suitability of CRANAD-2 for optical detection of Aβ deposits in animal models of AD pathology, which facilitates mechanistic studies and the monitoring of putative treatments targeting Aβ deposits.

Multichromatic fluorescence towards aberrant proteinaceous aggregates utilizing benzimidazole-based ICT fluorophores

The pathological origin of Alzheimer’s disease (AD) remains uncharted terrain, despite intensive investigation. Discriminating aberrant proteinaceous deposits, such as β-amyloid (Aβ) and (hyperphosphorylated) tau protein by imaging methods, is a vital tool to support investigations towards the network of interacting features that results in AD pathology. In this context, multispectral fluorescence imaging (MSFI) has drawn much attention enabling the distinction of several analytes with merely a single fluorophore emitting a multichromatic fluorescent signal. Herein, we developed three kinds of benzimidazole-derived fluorescent dyes, BZ1–BZ3. The photophysical properties and intramolecular charge transfer (ICT) characteristics of the probes were evaluated in various solvents. Furthermore, a benzimidazole-associated polar-sensitivity displayed multichromatic behavior and enabled the visualization of minute differences in microenvironmental polarity between Aβ and tau aggregates, resulting in different maximal fluorescent emission wavelengths. Indeed, BZ2 demonstrated an approximately 30 nm bathochromic shift in maximal fluorescent emission. All these observations offer a potential for the development of a future generation of benzimidazole-derived ICT-based fluorescent probes.