Dual/Multi-Modal Image-Guided Diagnosis and Therapy Based on Luminogens with Aggregation-Induced Emission

The combination of multiple imaging methods has made an indelible contribution to the diagnosis, surgical navigation, treatment, and prognostic evaluation of various diseases. Due to the unique advantages of luminogens with aggregation-induced emission (AIE), their progress has been significant in the field of organic fluorescent contrast agents. Herein, this manuscript summarizes the recent advancements in AIE molecules as contrast agents for optical image-based dual/multi-modal imaging. We particularly focus on the exceptional properties of each material and the corresponding application in the diagnosis and treatment of diseases.

Nanoscale Covalent Organic Framework with Staggered Stacking of Phthalocyanines for Mitochondria-Targeted Photodynamic Therapy

Phthalocyanine photosensitizers (PSs) have shown promise in fluorescence imaging and photodynamic therapy (PDT) of malignant tumors, but their practical application is limited by the aggregation-induced quenching (AIQ) and inherent photobleaching of PSs. Herein, we report the synthesis of a two-dimensional nanoscale covalent organic framework (nCOF) with staggered (AB) stacking of zinc-phthalocyanines (ZnPc), ZnPc-PI, for fluorescence imaging and mitochondria-targeted PDT. ZnPc-PI isolates and confines ZnPc PSs in the rigid nCOF to reduce AIQ, improve photostability, enhance cellular uptake, and increase the level of reactive oxygen species (ROS) generation via mitochondrial targeting. ZnPc-PI shows efficient tumor accumulation, which allowed precise tumor imaging and nanoparticle tracking. With high cellular uptake and tumor accumulation, intrinsic mitochondrial targeting, and enhanced ROS generation, ZnPc-PI exhibits potent PDT efficacy with >95% tumor growth inhibition on two murine colon cancer models without causing side effects.

A deep-red xanthene-based highly sensitive fluorescent probe for detection of hypochlorite

As an oxidant, deodorant and bleaching agent, the hypochlorous acid (HClO) and hypochlorite (ClO- ) are widely used in corrosion inhibitors, textile dyes, pharmaceutical intermediates and in our daily lives. However, excess usage or aberrant accumulation of ClO- leads to tissue damage or some diseases and even cancer. Therefore, it is necessary to develop a fluorescent probe that specifically identifies ClO- . In this article, we synthesized a deep-red xanthene-based fluorescent probe (XA-CN). The strong electron deficient group dicyano endows the probe XA-CN deep-red fluorescent emission with high solubility, selectivity and sensitivity for ClO- detection. Studies showed that the probe demonstrated turn-off fluorescence (643 nm) at the presence of ClO- in dimethylsulfoxide/phosphate-buffered saline 1:1 (pH 9) solution with a limit of detection of 1.64 μM. Detection mechanism investigation revealed that the electron deficient group -CN and the hydroxyl group was oxidized into aldehyde or carbonyl groups at the presence of ClO- , resulting ultraviolet-visible absorption of the probe blue shifted and turned-off fluorescence. Furthermore, XA-CN was successfully used for the detection of ClO- in tap water samples.

A ratiometric fluorescent probe for the detection of biological thiols based on a new supramolecular design

A new ratiometric fluorescent probe is designed and prepared based on the concept of supramolecular encapsulation and dye competition. This supramolecular probe is based on two commercially-available dyes, one common guest and a simple-to-synthesize host. Fluorescence spectroscopy confirms that the supramolecular probe is capable of detecting thiols quantitatively with a broad linear region in phosphate buffered saline or fetal bovine serum. Mechanistic study shows a reaction between thiol specie and the guest to alter the distribution of encapsulated dyes. The supramolecular probes are demonstrated to quantitatively detect extracellular biological thiols by plate reader, which shows it keeps its effectiveness in complex buffered systems.

Exceedingly Small Magnetic Iron Oxide Nanoparticles for T1 -Weighted Magnetic Resonance Imaging and Imaging-Guided Therapy of Tumors

Magnetic iron oxide nanoparticles (MIONs) based T2 -weighted magnetic resonance imaging (MRI) contrast agents (CAs) are liver-specific with good biocompatibility, but have been withdrawn from the market and replaced with Eovist (Gd-EOB-DTPA) due to their inherent limitations (e.g., susceptibility to artifacts, high magnetic moment, dark signals, long processing time of T2 imaging, and long waiting time for patients after administration). Without the disadvantages of Gd-chelates and MIONs, the recently emerging exceedingly small MIONs (ES-MIONs) (<5 nm) are promising T1 CAs for MRI. However, there are rare review articles focusing on ES-MIONs for T1 -weighted MRI. Herein, the recent progress of ES-MIONs, including synthesis methods (the current basic synthesis methods and improved methods), surface modifications (artificial polymers, natural polymers, zwitterions, and functional protein), T1 -MRI visual strategies (structural remodeling, reversible self-assemblies, metal ions doped, T1 /T2 dual imaging modes, and PET/MRI strategy), and imaging-guided cancer therapy (chemotherapy, gene therapy, ferroptosis therapy, photothermal therapy, photodymatic therapy, radiotherapy, immuotherapy, sonodynamic therapy, and multimode therapy), is summarized. The detailed description of synthesis methods and applications of ES-MIONs in this review is anticipated to attract extensive interest from researchers in different fields and promote their participation in the establishment of ES-MIONs based nanoplatforms for tumor theranostics.

Achieving safe and high-performance gastrointestinal tract spectral CT imaging with small-molecule lanthanide complex

BACKGROUND

Non-intrusive imaging of gastrointestinal (GI) tract using computed tomography (CT) contrast agents is of the most significant issues in the diagnosis and treatment of GI diseases. Moreover, spectral CT, which can generate monochromatic images to display the X-ray attenuation characteristics of contrast agents, provides a better imaging sensitivity for diagnose inflammatory bowel disease (IBD) than convention CT imaging.

METHODS

Herein, a convenient and one-pot synthesis method is provided for the fabrication of small-molecule lanthanide complex Holmium-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid (Ho-DOTA) as a biosafe and high-performance spectral CT contrast agent for GI imaging with IBD. In vivo CT imaging was administered with both healthy mice and colitis mice induced by dextran sodium sulfate.

RESULTS

We found that Ho-DOTA accumulated in inflammation sites of large intestines and produced high CT contrast compared with healthy mice. Both in vitro and in vivo experimental results also showed that Ho-DOTA provided much more diagnostic sensitivity and accuracy due to the excellent X-ray attenuation characteristics of Ho-DOTA compared with clinical iodinate agent. Furthermore, the proposed contrast media could be timely excreted from the body via the urinary and digestive system, keeping away from the potential side effects due to long-term retention in vivo.

CONCLUSION

Accordingly, Ho-DOTA with excellent biocompatibility can be useful as a potential high-performance spectral CT contrast agent for further clinical imaging of gastrointestinal tract and diagnosis of intestinal system diseases.

Functionalized Fluorescent Organic Nanoparticles Based AIE Enabling Effectively Targeting Cancer Cell Imaging

We report a fluorescent dye TM by incorporating the tetraphenylethylene (TPE) and cholesterol components into perylene bisimides (PBI) derivative. Fluorescence emission spectrum shows that the dye has stable red emission and aggregation-induced emission (AIE) characteristics. The incorporation of cholesterol components triggers TM to show induced chirality through supramolecular self-assembly. The cRGD-functionalized nanoparticles were prepared by encapsulating fluorescent dyes with amphiphilic polymer matrix. The functionalized fluorescent organic nanoparticles exhibit excellent biocompatibility, large Stokes' shift and good photostability, which make them effective fluorescent probes for targeting cancer cells with high fluorescence contrast.

Improved synthesis of DA364, an NIR fluorescence RGD probe targeting αvβ3 integrin

Optical imaging (OI) is gaining increasing attention in medicine as a non-invasive diagnostic imaging technology and as a useful tool for image-guided surgery. OI exploits the light emitted in the near-infrared region by fluorescent molecules able to penetrate living tissues. Cyanines are an important class of fluorescent molecules and by their conjugation to peptides it is possible to achieve optical imaging of tumours by selective targeting. We report here the improvements obtained in the synthesis of DA364, a small fluorescent probe (1.5 kDa) prepared by conjugation of pentamethine cyanine Cy5.5 to an RGD peptidomimetic, which can target tumour cells overexpressing integrin αvβ3 receptors.

Enhanced NIR-II Fluorescent Lateral Flow Biosensing Platform Based on Supramolecular Host-Guest Self-Assembly for Point-of-Care Testing of Tumor Biomarkers

Point-of-care detection of tumor biomarkers with high sensitivity remains an enormous challenge in the early diagnosis and mass screening of cancer. Fluorescent lateral flow immunoassay (LFA) is an attractive platform for point-of-care testing due to its inherent advantages. Particularly, a fluorescent probe is crucial to improving the analytical performance of the LFA platform. Herein, we developed an enhanced second near-infrared (NIR-II) LFA (ENIR-II LFA) platform based on supramolecular host-guest self-assembly for detection of the prostate-specific antigen (PSA) as a model analyte. In this platform, depending on the effective supramolecular surface modification strategy, cucurbit[7]uril (CB[7])-covered rare-earth nanoparticles (RENPs) emitting in the NIR-II (1000-1700 nm) window were prepared and employed as an efficient fluorescent probe (RENPs-CB[7]). Benefiting from its superior optical properties, such as low autofluorescence, excellent photostability, enhanced fluorescence intensity, and increased antibody-conjugation efficiency, the ENIR-II LFA platform displayed a wide linear detection range from 0.65 to 120 ng mL-1, and the limit of detection was down to 0.22 ng mL-1 for PSA, which was 18.2 times lower than the clinical cutoff value. Moreover, the testing time was also shortened to 6 min. Compared with the commercial visible fluorescence LFA kit (VIS LFA) and the previously reported NIR-II LFA based on a RENPs-PAA probe, this ENIR-II LFA demonstrated more competitive advantages in analytical sensitivity, detection range, testing time, and production cost. Overall, the ENIR-II LFA platform offers great potential for the highly sensitive, rapid, and convenient detection of tumor biomarkers and is expected to serve as a useful technique in the general population screening of the high-incidence cancer region.

Tumor Stimulus-Activatable Pretheranostic Agent: One Key to Three Locks

The uncontrollable distribution of antitumor agents remains a large obstacle for specific and efficient cancer theranostics; thus, efficient construction of tumor-specific systems is highly desirable. In this work, a general design of tumor stimulus-activatable pretheranostic agents was put forward via a series of structures-tunable triphenylamine derivatives (TPA-2T-FSQ, TPA-2T-BSZ, and TPA-2T-ML) with phenothiazine, benzothiazine, and thiomorpholine as identifying groups of hypochlorite (HClO), respectively. Notably, the sulfur atom in phenothiazine of TPA-2T-FSQ was more easily oxidized to sulfoxide groups by HClO, transforming into an electron acceptor to form an excellent push-pull electronic system, which was beneficial to a large redshift of absorbance and emission wavelengths. Based on this, TPA-2T-FSQ resorted to a key of overexpressed HClO in the tumor to open "three locks", viz, NIR fluorescence, photothermal, and photoacoustic signals for multimodal diagnostic and treatment of the tumor. This study provided an elegant design to adopt tumor stimulus-triggerable pretheranostic for improving theranostic accuracy and efficiency, which was regarded as a promising candidate for precision medicine.

Cuproptosis: Harnessing Transition Metal for Cancer Therapy

Transition metal elements, such as copper, play diverse and pivotal roles in oncology. They act as constituents of metalloenzymes involved in cellular metabolism, function as signaling molecules to regulate the proliferation and metastasis of tumors, and are integral components of metal-based anticancer drugs. Notably, recent research reveals that excessive copper can also modulate the occurrence of programmed cell death (PCD), known as cuprotosis, in cancer cells. This modulation occurs through the disruption of tumor cell metabolism and the induction of proteotoxic stress. This discovery uncovers a mode of interaction between transition metals and proteins, emphasizing the intricate link between copper homeostasis and tumor metabolism. Moreover, they provide innovative therapeutic strategies for the precise diagnosis and treatment of malignant tumors. At the crossroads of chemistry and oncology, we undertake a comprehensive review of copper homeostasis in tumors, elucidating the molecular mechanisms underpinning cuproptosis. Additionally, we summarize current nanotherapeutic approaches that target cuproptosis and provide an overview of the available laboratory and clinical methods for monitoring this process. In the context of emerging concepts, challenges, and opportunities, we emphasize the significant potential of nanotechnology in the advancement of this field.

A General Strategy Toward pH-Resistant Phenolic Fluorophores for High-Fidelity Sensing and Bioimaging Applications

Aryl alcohol-type or phenolic fluorophores offer diverse opportunities for developing bioimaging agents and fluorescence probes. Due to the inherently acidic hydroxyl functionality, phenolic fluorophores provide pH-dependent emission signals. Therefore, except for developing pH probes, the pH-dependent nature of phenolic fluorophores should be considered in bioimaging applications but has been neglected. Here we show that a simple structural remedy converts conventional phenolic fluorophores into pH-resistant derivatives, which also offer "medium-resistant" emission properties. The structural modification involves a single-step introduction of a hydrogen-bonding acceptor such as morpholine nearby the phenolic hydroxyl group, which also leads to emission bathochromic shift, increased Stokes shift, enhanced photo-stability and stronger emission for several dyes. The strategy greatly expands the current fluorophores' repertoire for reliable bioimaging applications, as demonstrated here with ratiometric imaging of cells and tissues.

Cell membrane targetable NIR fluorescent polarity probe for selective visualization of cancer cells and early tumor

The development of a sensitive method for early cancer diagnosis is very important because the early diagnosis of cancer is crucial in preventing the spread of cancer cells and improving patient survival rates. Recent studies showed that cancer cell membranes have lower polarity than normal cell membranes, which provides a new approach for cancer diagnosis at the cell membrane level. We developed herein a highly sensitive cell membrane polarity probe (Cal-M) for early diagnosis of cancer. This probe has low cytotoxicity, good photostability, near-infrared (NIR) fluorescence emission (>700 nm), large Stokes shift, high sensitivity for polarity, excellent cell membrane localization performance, and the ability to selectively light up cancer cells. Using this probe staining, the fluorescence of cancer cells is ∼63 times higher than that of normal cells, demonstrating excellent sensitivity and selectivity of Cal-M. This probe was also successfully used to detect polarity changes on cancer cell membranes and selectively visualize tumors in mice. Notably, the tumor could be visualized sensitively with a size as small as 1.37 mm3, indicating that Cal-M is promising for early diagnosis of tumors.

Spherical nucleic acids-based nanoplatforms for tumor precision medicine and immunotherapy

Precise diagnosis and treatment of tumors currently still face considerable challenges due to the development of highly degreed heterogeneity in the dynamic evolution of tumors. With the rapid development of genomics, personalized diagnosis and treatment using specific genes may be a robust strategy to break through the bottleneck of traditional tumor treatment. Nevertheless, efficient in vivo gene delivery has been frequently hampered by the inherent defects of vectors and various biological barriers. Encouragingly, spherical nucleic acids (SNAs) with good modularity and programmability are excellent candidates capable of addressing traditional gene transfer-associated issues, which enables SNAs a precision nanoplatform with great potential for diverse biomedical applications. In this regard, there have been detailed reviews of SNA in drug delivery, gene regulation, and dermatology treatment. Still, to the best of our knowledge, there is no published systematic review summarizing the use of SNAs in oncology precision medicine and immunotherapy, which are considered new guidelines for oncology treatment. To this end, we summarized the notable advances in SNAs-based precision therapy and immunotherapy for tumors following a classification standard of different types of precise spatiotemporal control on active species by SNAs. Specifically, we focus on the structural diversity and programmability of SNAs. Finally, the challenges and possible solutions were discussed in the concluding remarks. This review will promote the rational design and development of SNAs for tumor-precise medicine and immunotherapy.

Near-infrared photodynamic and photothermal co-therapy based on organic small molecular dyes

Near-infrared (NIR) organic small molecule dyes (OSMDs) are effective photothermal agents for photothermal therapy (PTT) due to their advantages of low cost and toxicity, good biodegradation, and strong NIR absorption over a wide wavelength range. Nevertheless, OSMDs have limited applicability in PTT due to their low photothermal conversion efficiency and inadequate destruction of tumor regions that are nonirradiated by NIR light. However, they can also act as photosensitizers (PSs) to produce reactive oxygen species (ROS), which can be further eradicated by using ROS-related therapies to address the above limitations of PTT. In this review, the synergistic mechanism, composition, and properties of photodynamic therapy (PDT)-PTT nanoplatforms were comprehensively discussed. In addition, some specific strategies for further improving the combined PTT and PDT based on OSMDs for cancer to completely eradicate cancer cells were outlined. These strategies include performing image-guided co-therapy, enhancing tumor infiltration, increasing H2O2 or O2 in the tumor microenvironment, and loading anticancer drugs onto nanoplatforms to enable combined therapy with phototherapy and chemotherapy. Meanwhile, the intriguing prospects and challenges of this treatment modality were also summarized with a focus on the future trends of its clinical application.

X-Ray-Induced Drug Release for Cancer Therapy

Drug delivery systems (DDSs) are designed to deliver therapeutic agents to specific target sites while minimizing systemic toxicity. Recent developments in drug-loaded DDSs have demonstrated promising characteristics and paved new pathways for cancer treatment. Light, a prevalent external stimulus, is widely utilized to trigger drug release. However, conventional light sources primarily concentrate on the ultraviolet (UV) and visible light regions, which suffer from limited biological tissue penetration. This limitation hinders applications for deep-tissue tumor drug release. Given their deep tissue penetration and well-established application technology, X-rays have recently received attention for the pursuit of controlled drug release. With precise spatiotemporal and dosage controllability, X-rays stand as an ideal stimulus for achieving controlled drug release in deep-tissue cancer therapy. This article explores the recent advancements in using X-rays for stimulus-triggered drug release in DDSs and delves into their action mechanisms.

A S-substituted Nile Blue-derived bifunctional near-infrared fluorescent probe for in vivo carboxylesterase imaging-guided photodynamic therapy of hepatocellular carcinoma

The development of theranostic probes that integrate both diagnostic and therapeutic functions still remains an intractable challenge in precise cancer treatment. Herein, a novel bifunctional near-infrared (NIR) fluorescent probe (CEP1) for carboxylesterase (CE) imaging and photodynamic therapy (PDT) of hepatocellular carcinoma (HCC) has been firstly developed and successfully applied in vitro and in vivo. The probe was constructed by introducing carbamate as both the recognition unit and the fluorescence quenching unit into the fluorophore S-substituted Nile Blue (ENBS) via a self-eliminating spacer with substituted chloride. It can be activated by CE and hydrolyzed into fluorescent ENBS, which recover fluorescence at about 700 nm, and can generate superoxide radical anions under NIR irradiation. Additionally, the probe could effectively distinguish tumor cells from normal cells by CE imaging of live cells. Furthermore, it could achieve CE imaging in vivo and significantly inhibits tumor growth by imaging-guided PDT. Therefore, this study offers a promising and attractive platform for activatable imaging-guided PDT of HCC.

A Tetrazine-Caged Carbon-Dipyrromethene as a Bioorthogonally Activatable Fluorescent Probe

A water-soluble 1,2,4,5-tetrazine-substituted carbon-dipyrromethene (C-DIPY) was synthesized from the previously reported carbonyl pyrrole dimer through a two-step procedure. Owing to the presence of a tetrazine moiety, the fluorescence emission of this compound was largely quenched in phosphate-buffered saline at pH 7.4. Upon addition of a bicyclo[6.1.0]non-4-yne (BCN) derivative, the tetrazine-based quenching component of the compound was disrupted through the inverse electron-demand Diels-Alder reaction to restore the fluorescence in up to 6.6-fold. This bioorthogonal activation was also demonstrated using U-87 MG human glioblastoma cells, in which the fluorescence intensity of this C-DIPY could be enhanced by 8.7-fold upon post-incubation with the BCN derivative. The results showed that this tetrazine-caged C-DIPY can serve as a bioorthogonally activatable fluorescent probe for bioimaging. The compound, however, was found to reside preferentially in the lysosomes instead of the mitochondria of the cells as predicted based on its cationic character, which could be attributed to its energy-dependent endocytic cellular uptake pathway, for which lysosomes are the end station.

Glycolysis-based drug delivery nanosystems for therapeutic use in tumors and applications

Tumor cells are able to use glycolysis to produce energy under hypoxic conditions, and even under aerobic conditions, they rely mainly on glycolysis for energy production, the Warburg effect. Conventional tumor therapeutic drugs are unidirectional, lacking in targeting and have limited therapeutic effect. The development of a large number of nanocarriers and targeted glycolysis for the treatment of tumors has been extensively investigated in order to improve the therapeutic efficacy. This paper reviews the research progress of nanocarriers based on targeting key glycolytic enzymes and related transporters, and combines nanocarrier systems with other therapeutic approaches to provide a new strategy for targeted glycolytic treatment of tumors, providing a theoretical reference for achieving efficient targeted treatment of tumors.

A NIR-Activated and Mild-Temperature-Sensitive Nanoplatform with an HSP90 Inhibitor for Combinatory Chemotherapy and Mild Photothermal Therapy in Cancel Cells

Mild photothermal therapy (PTT) shows great potential to treat cancers while avoiding unwanted damage to surrounding normal cells. However, the efficacy of mild PTT is normally moderate because of the low hyperthermia temperature and limited light penetration depth. Chemotherapy has unlimited penetration but often suffers from unsatisfactory efficacy in view of the occurrence of drug resistance, suboptimal drug delivery and release profile. As a result, the combinatory of chemotherapy and mild PTT would integrate their advantages and overcome the shortcomings. Herein, we synthesized an NIR-activatable and mild-temperature-sensitive nanoplatform (BDPII-gel@TSL) composed of temperature-sensitive liposomes (TSL), heat shock protein 90 (HSP90) inhibitor (geldanamycin) and photothermal agent (BDPII), for dual chemotherapy and mild PTT in cancer cells. BDPII, constructed with donor-acceptor moieties, acts as an excellent near-infrared (NIR) photothermal agent (PTA) with a high photothermal conversion efficiency (80.75%). BDPII-containing TSLs efficiently produce a mild hyperthermia effect (42 °C) under laser irradiation (808 nm, 0.5 W cm-2). Importantly, the phase transformation of TSL leads to burst release of geldanamycin from BDPII-gel@TSL, and this contributes to down-regulation of the overexpression of HSP90, ensuring efficient inhibition of cancer cell growth. This research provides a dual-sensitive synergistic therapeutic strategy for cancer cell treatment.

New Advances in the Exploration of Esterases with PET and Fluorescent Probes

Esterases are hydrolases that catalyze the hydrolysis of esters into the corresponding acids and alcohols. The development of fluorescent probes for detecting esterases is of great importance due to their wide spectrum of biological and industrial applications. These probes can provide a rapid and sensitive method for detecting the presence and activity of esterases in various samples, including biological fluids, food products, and environmental samples. Fluorescent probes can also be used for monitoring the effects of drugs and environmental toxins on esterase activity, as well as to study the functions and mechanisms of these enzymes in several biological systems. Additionally, fluorescent probes can be designed to selectively target specific types of esterases, such as those found in pathogenic bacteria or cancer cells. In this review, we summarize the recent fluorescent probes described for the visualization of cell viability and some applications for in vivo imaging. On the other hand, positron emission tomography (PET) is a nuclear-based molecular imaging modality of great value for studying the activity of enzymes in vivo. We provide some examples of PET probes for imaging acetylcholinesterases and butyrylcholinesterases in the brain, which are valuable tools for diagnosing dementia and monitoring the effects of anticholinergic drugs on the central nervous system.

Photophysical Exploration of Alectinib and Rilpivirine: Insights from Theory and Experiment

Due to the excellent characteristics of fluorescence-based imaging, such as non-invasive detection of biomarkers in vitro and in vivo with high sensitivity, good spatio-temporal resolution and fast response times, it has shown significant prospects in various applications. Compounds with both biological activities and fluorescent properties have the potential for integrated diagnosis and treatment application. Alectinib and Rilpivirine are two excellent drugs on sale that represent a clinically approved targeted therapy for ALK-rearranged NSCLC and have exhibited more favorable safety and tolerance profiles in Phase III clinical trials, ECHO and THRIVE, respectively. The optical properties of these two drugs, Alectinib and Rilpivirine, were deeply explored, firstly through the simulation of molecular structures, electrostatic potential, OPA/TPA and emission spectral properties and experiments on UV-vis spectra, fluorescence and cell imaging. It was found that Alectinib exhibited 7.8% of fluorescence quantum yield at the 450 nm excited wavelength, due to a larger electronic transition dipole moment (8.41 Debye), bigger charge transition quantity (0.682 e) and smaller reorganization energy (2821.6 cm-1). The stronger UV-vis spectra of Rilpivirine were due to a larger electron-hole overlap index (Sr: 0.733) and were also seen in CDD plots. Furthermore, Alectinib possessed obvious active two-photon absorption properties (δmaxTPA* ϕ = 201.75 GM), which have potential TPA imaging applications in bio-systems. Lastly, Alectinib and Rilpivirine displayed green fluorescence in HeLa cells, suggesting the potential ability for biological imaging. Investigation using theoretical and experimental methods is certainly encouraged, given the particular significance of developing integrated diagnosis and treatment.

Small-molecule probes from bench to bedside: advancing molecular analysis of drug-target interactions toward precision medicine

Over the past decade, remarkable advances have been witnessed in the development of small-molecule probes. These molecular tools have been widely applied for interrogating proteins, pathways and drug-target interactions in preclinical research. While novel structures and designs are commonly explored in probe development, the clinical translation of small-molecule probes remains limited, primarily due to safety and regulatory considerations. Recent synergistic developments - interfacing novel chemical probes with complementary analytical technologies - have introduced and expedited diverse biomedical opportunities to molecularly characterize targeted drug interactions directly in the human body or through accessible clinical specimens (e.g., blood and ascites fluid). These integrated developments thus offer unprecedented opportunities for drug development, disease diagnostics and treatment monitoring. In this review, we discuss recent advances in the structure and design of small-molecule probes with novel functionalities and the integrated development with imaging, proteomics and other emerging technologies. We further highlight recent applications of integrated small-molecule technologies for the molecular analysis of drug-target interactions, including translational applications and emerging opportunities for whole-body imaging, tissue-based measurement and blood-based analysis.

Fluorescent dyes based on rhodamine derivatives for bioimaging and therapeutics: recent progress, challenges, and prospects

Since their inception, rhodamine dyes have been extensively applied in biotechnology as fluorescent markers or for the detection of biomolecules owing to their good optical physical properties. Accordingly, they have emerged as a powerful tool for the visualization of living systems. In addition to fluorescence bioimaging, the molecular design of rhodamine derivatives with disease therapeutic functions (e.g., cancer and bacterial infection) has recently attracted increased research attention, which is significantly important for the construction of molecular libraries for diagnostic and therapeutic integration. However, reviews focusing on integrated design strategies for rhodamine dye-based diagnosis and treatment and their wide application in disease treatment are extremely rare. In this review, first, a brief history of the development of rhodamine fluorescent dyes, the transformation of rhodamine fluorescent dyes from bioimaging to disease therapy, and the concept of optics-based diagnosis and treatment integration and its significance to human development are presented. Next, a systematic review of several excellent rhodamine-based derivatives for bioimaging, as well as for disease diagnosis and treatment, is presented. Finally, the challenges in practical integration of rhodamine-based diagnostic and treatment dyes and the future outlook of clinical translation are also discussed.

Second window indocyanine green localizes CNS lymphoma in real time in the operating room: report of two cases

Intraoperative distinction of lesional tissue versus normal brain parenchyma can be difficult in neurosurgical oncology procedures. We report the successful, real-time visualization of central nervous system (CNS) lymphoma using the 'Second Window Indocyanine Green' (SWIG) method for two patients who underwent craniotomy for pathology that was determined to be large B cell lymphoma. Indocyanine green (ICG), when administered intravenously the day prior to cranial surgery, is a re-purposed fluorophore that may afford safe, immediate visual confirmation of on-target tissue resection, thereby providing a valuable adjunct to intraoperative navigation and decreasing reliance on frozen pathology analysis. These first reported cases of SWIG for lymphoma in the CNS indicate that further study of fluorophores to improve biopsy targeting and yield is warranted.

A lysosomes and mitochondria dual-targeting AIE-active NIR photosensitizer: Constructing amphiphilic structure for enhanced antitumor activity and two-photon imaging

Development of lysosomes and mitochondria dual-targeting photosensitizer with the virtues of near-infrared (NIR) emission, highly efficient reactive oxygen generation, good phototoxicity and biocompatibility is highly desirable in the field of imaging-guided photodynamic therapy (PDT) for cancer. Herein, a new positively charged amphiphilic organic compound (2-(2-(5-(7-(4-(diphenylamino)phenyl)benzo[c][1,2,5]thiadiazol-4-yl)thiophen-2-yl)vinyl)-3-methylbenzo[d]thiazol-3-ium iodide) (ADB) based on a D-A-π-A structure is designed and comprehensively investigated. ADB demonstrates special lysosomes and mitochondria dual-organelles targeting, bright NIR aggregation-induced emission (AIE) at 736 ​nm, high singlet oxygen (¹O₂) quantum yield (0.442), as well as good biocompatibility and photostability. In addition, ADB can act as a two-photon imaging agent for the elaborate observation of living cells and blood vessel networks of tissues. Upon light irradiation, obvious decrease of mitochondrial membrane potential (MMP), abnormal mitochondria morphology, as well as phagocytotic vesicles and lysosomal disruption in cells are observed, which further induce cell apoptosis and resulting in enhanced antitumor activity for cancer treatment. In vivo experiments reveal that ADB can inhibit tumor growth efficiently upon light exposure. These findings demonstrate that this dual-organelles targeted ADB has great potential for clinical imaging-guided photodynamic therapy, and this work provides a new avenue for the development of multi-organelles targeted photosensitizers for highly efficient cancer treatment.

Accurate imaging in the processes of formation and inhibition of drug-induced liver injury by an activable fluorescent probe for ONOO. Mater Today Bio 2023;21:100689. [PMID: 37448665 PMCID: PMC10336156 DOI: 10.1016/j.mtbio.2023.100689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Herein, an activable fluorescent probe for peroxynitrite (ONOO^-), named NOP, was constructed for the accurate imaging in the processes of formation and inhibition of drug-induced liver injury induced by Acetaminophen (APAP). During the in-solution tests on the general optical properties, the probe showed advantages including good stability, wide pH adaption, high specificity and sensitivity in the monitoring of ONOO^-. Subsequently, the probe was further applied in the model mice which used APAP to induce the injury and used inhibiting agents (GSH, Glu, NAC) to treat the induced injury. The construction of the liver injury model was confirmed by the pathological staining and the serum indexes including ALT, AST, ALP, TBIL as well as LDH. During the formation of the drug-induced liver injury, the fluorescence in the red channel enhanced in both time-dependent and dose-dependent manners. In inhibition tests, the inhibition of the liver injury exhibited the reduction of the fluorescence intensity. Therefore, NOP could achieve the accurate imaging in the processes of formation and inhibition of drug-induced liver injury. The information here might be helpful for the early diagnosis and the screening of potent treating candidates in liver injury cases.

Engineering of a GSH activatable photosensitizer for enhanced photodynamic therapy through disrupting redox homeostasis

Although disrupted redox homeostasis has emerged as a promising approach for tumor therapy, most existing photosensitizers are not able to simultaneously improve the reactive oxygen species level and reduce the glutathione (GSH) level. Therefore, designing photosensitizers that can achieve these two aspects of this goal is still urgent and challenging. In this work, an organic activatable near-infrared (NIR) photosensitizer, CyI-S-diCF₃, is developed for GSH depletion-assisted enhanced photodynamic therapy. CyI-S-diCF₃, composed of an iodinated heptamethine cyanine skeleton linked with a recognition unit of 3,5-bis(trifluoromethyl)benzenethiol, can specifically react with GSH by nucleophilic substitution, resulting in intracellular GSH depletion and redox imbalance. Moreover, the activated photosensitizer can produce abundant singlet oxygen (¹O₂) under NIR light irradiation, further heightening the cellular oxidative stress. By this unique nature, CyI-S-diCF₃ exhibits excellent toxicity to cancer cells, followed by inducing earlier apoptosis. Thus, our study may propose a new strategy to design an activatable photosensitizer for breaking the redox homeostasis in tumor cells.

Synthesis and Characterization of Novel Thienothiadiazole-Based D-π-A-π-D Fluorophores as Potential NIR Imaging Agents

As fluorescence bioimaging has increased in popularity, there have been numerous reports on designing organic fluorophores with desirable properties amenable to perform this task, specifically fluorophores with emission in the near-infrared II (NIR-II) region. One such strategy is to utilize the donor-π-acceptor-π-donor approach (D-π-A-π-D), as this allows for control of the photophysical properties of the resulting fluorophores through modulation of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy levels. Herein, we illustrate the properties of thienothiadiazole (TTD) as an effective acceptor moiety in the design of NIR emissive fluorophores. TTD is a well-known electron-deficient species, but its use as an acceptor in D-π-A-π-D systems has not been extensively studied. We employed TTD as an acceptor unit in a series of two fluorophores and characterized the photophysical properties through experimental and computational studies. Both fluorophores exhibited emission maxima in the NIR-I that extends into the NIR-II. We also utilized electron paramagnetic resonance (EPR) spectroscopy to rationalize differences in the measured quantum yield values and demonstrated, to our knowledge, the first experimental evidence of radical species on a TTD-based small-molecule fluorophore. Encapsulation of the fluorophores using a surfactant formed polymeric nanoparticles, which were studied by photophysical and morphological techniques. The results of this work illustrate the potential of TTD as an acceptor in the design of NIR-II emissive fluorophores for fluorescence bioimaging applications.

Multiple organelle-targeted 1,8-naphthyridine derivatives for detecting the polarity of organelles

Four 1,8-naphthyridine derivatives (1a-1d) with different organelle targeting abilities were obtained using the Knoevenagel condensation reaction of 1,8-naphthyridine with 4-(N,N-diethylamino)benzaldehyde (2a), 4-(N,N-diphenylamino)benzaldehyde (2b), 4-(piperazin-1-yl)benzaldehyde (2c) and 4-(ethyl(4-formylphenyl)amino)-N-(2-((4-methylphenyl)sulfonamido)ethyl)butanamide (2d), respectively. The maximal absorption bands of dyes 1a-1d were observed at 375-447 nm, while their maximum emission peaks were situated at 495-605 nm. The optical properties showed that the fluorescence emission of dyes 1a-1d is shifted toward greater wavelengths as the system polarity (Δf) increased. Meanwhile, with increasing polarity of the mixed 1,4-dioxane/H₂O system, the fluorescence intensity of dyes 1a-1d gradually decreased. Furthermore, the fluorescence intensity of 1a-1d enhanced by 12-239 fold as the polarity of 1,4-dioxane/H₂O mixtures declined. 1a-1d had a large Stokes shift (up to 229 nm) in polar solvents in comparison to nonpolar solvents. The colocalization imaging experiments demonstrated that dyes 1a-1d (3-10 μM) were located in mitochondria, lipid droplets, lysosomes and the endoplasmic reticulum in living HeLa cells, respectively; and they could monitor the polarity fluctuation of the corresponding organelles. Consequently, this work proposes a molecular design idea with different organelle targeting capabilities based on the same new fluorophore, and this molecular design idea may provide more alternatives for polarity-sensitive fluorescent probes with organelle targeting.

Investigation of the Relationship between Electronic Structures and Bioactivities of Polypyridyl Ru(II) Complexes

Ruthenium (Ru)-based organometallic drugs have gained attention as chemotherapeutic and bioimaging agents due to their fewer side effects and excellent physical optical properties. Tuning the electronic structures of Ru complexes has been proven to increase the cytotoxicity of cancer cells and the luminescent efficiency of the analytical probes. However, the relationship between electronic structures and bioactivities is still unclear due to the potential enhancement of both electron donor and acceptor properties. Thus, we investigated the relationship between the electronic structures of Ru(II) complexes and cytotoxicity by optimizing the electron-withdrawing (complex 1), electron-neutral (complex 2), and electron-donating (complex 3) ligands through DFT calculations, bioactivities tests, and docking studies. Our results indicated that it was not sufficient to consider only either the effect of electron-withdrawing or electron-donating effects on biological activities instead of the total electronic effects. Furthermore, these complexes with electron-donating substituents (complex 3) featured unique "off-on" luminescent emission phenomena caused by the various "HOMO-LUMO" distributions when they interacted with DNA, while complex with electron-withdrawing substituent showed an "always-on" signature. These findings offer valuable insight into the development of bifunctional chemotherapeutic agents along with bioimaging ability.

Polysiloxane-based hyperbranched fluorescent probe for dynamic visualization of HClO in lysosomes and vivo

As a type of reactive oxygen species, hypochlorous acid (HClO) is associated with inducing oxidative stress in lysosomes. Once its concentration is abnormal, it may lead to lysosomal rupture and subsequent apoptosis. Meanwhile, this may provide new inspiration for cancer treatment. Therefore, it is crucial to visualize HClO in lysosomes at the biological level. So far, numerous fluorescent probes have emerged to identify HClO. However, fluorescent probes that combine low biotoxicity with lysosome-targetable properties are scarce. In this paper, hyperbranched polysiloxanes were modified by embedding perylenetetracarboxylic anhydride red fluorescent cores with naphthalimide derivative green fluorophores to synthesize novel fluorescent probe (PMEA-1). PMEA-1 was a lysosome-targetable fluorescent probe with unique dual emission, high biosafety, and good response speed. PMEA-1 exhibited excellent sensitivity and responsiveness to HClO in PBS solution and could dynamically visualize HClO fluctuations in cells and zebrafish. Simultaneously, PMEA-1 also had monitoring ability for HClO produced in the process of cellular ferroptosis. In addition, the bioimaging results indicated that PMEA-1 was capable of accumulating within the lysosomes. We anticipate that PMEA-1 will broaden the application of silicon-based fluorescent probes in the field of fluorescence imaging.

NIR C-Myc Pu22 G-quadruplex probe as a photosensitizer for bioimaging and antitumor study

Despite the fact that C-Myc G-quadruplex in the oncogene promoter regions is one of the crucial targets of antitumor drugs, the selectivities and proliferation inhibitions of its probes towards tumor cells remain a big challenge. Until now, no effective C-Myc G-quadruplex probes have been reported as a photosensitizer to increase their antitumor activities. Here, the first NIR C-Myc G-quadruplex probe PDS-SQ has been designed, comprising a G-quadruplex binder PDS and a squaraine dye SQ as a photosensitizer. Conjugate PDS-SQ could selectively NIR image C-Myc Pu22 G-quadruplex in tumor cells, and show stronger antitumor activity in the irradiation by a chemo-photodynamic method than in the dark. The study provides a new way to develop the novel NIR C-Myc G-quadruplex probes with more potent antitumor activities.

Combining a protein-targeting small molecule and a thiol-targeting small molecule for detecting a serum risk marker of liver tumor recurrence

This work proposes a novel bioassay designed to detect the 2B receptor of serotonin in serum samples, which can serve as a risk marker for cancer recurrence after surgical resection. Traditional methods for detecting this marker are often costly and time-consuming, requiring specialized reagents and equipment. The new bioassay is designed to enable direct and reagent-less detection of the 2B receptor in serum samples, without the need of antibodies or enzymes. The assay uses a small molecule ligand for the 2B receptor combined with a thiol-targeting fluorescent dye on a compact peptide-based molecular frame. This design allows for a rapid and specific readout of the fluorescent signal upon probe-protein interaction. In addition, the covalent biosensing process used in the assay allows for signal enhancement by electrochemical cross-linking of serum proteins. The bioassay was successfully used to detect the 2B receptor in serum samples from hepatocarcinoma patients, indicating its potential as a powerful tool for early cancer detection and monitoring.

A long-wavelength mitochondria-targeted fluorescent probe for imaging of peroxynitrite during dexamethasone treatment

Peroxynitrite (ONOO^-), as a strong oxidizing reactive nitrogen substance (RNS), is generated endogenously by cells. Its visualization research is crucial to understand relevant disease processes. Herein, we reported a long-wavelength mitochondria-targeted fluorescence "turn on" probe TL. The probe TL could react with ONOO^- by using 4-(Bromomethyl)benzeneboronic as a reactive site, which exhibited outstanding characteristics for detection of ONOO^-, thus improving response time (about 50 s), sensitivity (DL, 10.1 nM), and emission wavelength (667 nm). Besides, TL displayed well mitochondria targeting and biological visualizing of exogenous and endogenous ONOO^- in biological systems. Finally, TL was used to monitor high concentration of dexamethasone-induced an up-regulation of ONOO^-. This indicated that TL has excellent potential to study the fluctuation of ONOO^- in the physiological and pathological system.

Tumor microenvironment signaling and therapeutics in cancer progression

Tumor development and metastasis are facilitated by the complex interactions between cancer cells and their microenvironment, which comprises stromal cells and extracellular matrix (ECM) components, among other factors. Stromal cells can adopt new phenotypes to promote tumor cell invasion. A deep understanding of the signaling pathways involved in cell-to-cell and cell-to-ECM interactions is needed to design effective intervention strategies that might interrupt these interactions. In this review, we describe the tumor microenvironment (TME) components and associated therapeutics. We discuss the clinical advances in the prevalent and newly discovered signaling pathways in the TME, the immune checkpoints and immunosuppressive chemokines, and currently used inhibitors targeting these pathways. These include both intrinsic and non-autonomous tumor cell signaling pathways in the TME: protein kinase C (PKC) signaling, Notch, and transforming growth factor (TGF-β) signaling, Endoplasmic Reticulum (ER) stress response, lactate signaling, Metabolic reprogramming, cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) and Siglec signaling pathways. We also discuss the recent advances in Programmed Cell Death Protein 1 (PD-1), Cytotoxic T-Lymphocyte Associated Protein 4 (CTLA4), T-cell immunoglobulin mucin-3 (TIM-3) and Lymphocyte Activating Gene 3 (LAG3) immune checkpoint inhibitors along with the C-C chemokine receptor 4 (CCR4)- C-C class chemokines 22 (CCL22)/ and 17 (CCL17), C-C chemokine receptor type 2 (CCR2)- chemokine (C-C motif) ligand 2 (CCL2), C-C chemokine receptor type 5 (CCR5)- chemokine (C-C motif) ligand 3 (CCL3) chemokine signaling axis in the TME. In addition, this review provides a holistic understanding of the TME as we discuss the three-dimensional and microfluidic models of the TME, which are believed to recapitulate the original characteristics of the patient tumor and hence may be used as a platform to study new mechanisms and screen for various anti-cancer therapies. We further discuss the systemic influences of gut microbiota in TME reprogramming and treatment response. Overall, this review provides a comprehensive analysis of the diverse and most critical signaling pathways in the TME, highlighting the associated newest and critical preclinical and clinical studies along with their underlying biology. We highlight the importance of the most recent technologies of microfluidics and lab-on-chip models for TME research and also present an overview of extrinsic factors, such as the inhabitant human microbiome, which have the potential to modulate TME biology and drug responses.

FRET-based fluorescent probe with favorable water solubility for simultaneous detection of SO2 derivatives and viscosity

The intracellular viscosity is an important parameter of the microenvironment and SO₂ is a vital gas signal molecule. At present, some dual-response fluorescence probes for simultaneous measurements of viscosity and SO₂ derivatives (HSO₃^-/SO₃^2-) possessed poor water solubility. In this work, we developed a water-soluble fluorescence probe CIJ (0.0864 g/100 mL of water at 20 °C) for simultaneous measurements of viscosity and SO₂ derivatives. CIJ exhibited a sensitive fluorescence enhancement to environmental viscosity from 0.97 to 28.04 cP based on a twisted intramolecular charge transfer mechanism and was applied to effective measurement of viscosity in vitro and in vivo. CIJ could also respond to SO₂ derivatives with a low detection limit (44 nM) and a fast response time (5 min) based on the nucleophilic addition reaction. Furthermore, CIJ was applied to monitor SO₂ derivatives in ratiometric response manner in living cells.

Selective Visualization of Tumor Cell Membranes and Tumors with a Viscosity-Sensitive Plasma Membrane Probe

Cancer is a worldwide health problem. Revealing the changes in the microenvironment after cell carcinogenesis is helpful to understand cancer and develop sensitive methods for cancer diagnosis. We developed herein a viscosity-responsive plasma membrane probe (TPA-S) that was successfully used to probe the viscosity difference between normal and tumor cell plasma membranes for the first time. The probe shows AIE properties with good water solubility, significant near-infrared (NIR) fluorescence responses to viscosity with high sensitivity, and excellent cell membrane location performance. With these features, our experiments showed that TPA-S could selectively visualize cancer cell plasma membranes, revealing that the plasma membrane of tumor cells is more viscous than that of normal cells. In addition, TPA-S was successfully applied to specifically light up tumors. Altogether, this work explored the changes of cell membrane viscosity after canceration, provided a new method for selective visualization of tumor cells, and opened up a new approach for cancer diagnosis.

Design and Synthesis of a Novel ICT Bichromophoric pH Sensing System Based on 1,8-Naphthalimide Fluorophores as a Two-Input Logic Gate and Its Antibacterial Evaluation

The synthesis, sensor activity, and logic behavior of a novel 4-iminoamido-1,8-naphthalimide bichromophoric system based on a "fluorophore-receptor" architecture with ICT chemosensing properties is reported. The synthesized compound showed good colorimetric and fluorescence signaling properties as a function of pH and proved itself as a promising probe for the rapid detection of pH in an aqueous solution and base vapors in a solid state. The novel dyad is able to work as a two-input logic gate with chemical inputs H⁺ (Input 1) and HO^- (Input 2) executing INHIBIT logic gate. The synthesized bichromophoric system and the corresponding intermediates demonstrated good antibacterial activity toward Gram (+) and Gram (-) bacteria when compared with the Gentamycin standard.

A novel GSH-activable theranostic probe containing kinase inhibitor for synergistic treatment and selective imaging of tumor cells

Theranostic probe is becoming a powerful tool for diagnosis and treatment of cancer. Although some theranostic probes have been successfully developed, there is still a great room for improvement in sensitive diagnosis and efficient treatment. Herein, we developed a novel GSH-activable theranostic probe NC-G, which uses 1,8-naphthalimide-4-sulfonamide as a fluorescence imaging group and crizotinib as a highly toxic kinase inhibitor to tumor cells. The probe not only has high sensitivity (DL = 74 nM) and specificity, but also can detect GSH sensitively in cells and zebrafish. In addition, probe NC-G can not only show more obvious fluorescence in tumor cells to achieve sensitive diagnosis of tumor cells, but also release the inhibitor crizotinib to achieve high toxicity to tumor cells. It is worth noting that the consumption of GSH can cause oxidative stress response of cells and the release of SO₂ can induce cell apoptosis during the recognition process of the probe and GSH. Thus, the synergistic effect of crizotinib, GSH depletion, and SO₂ release provides a highly effective therapeutic feature for tumor cells. Therefore, probe NC-G can serve as an excellent theranostic probe for sensitive imaging and highly effective treatment of tumor cells.

Homogeneous, Simple, and Direct Analysis of Exosomal PD-L1 via Aptamer-Bivalent-Cholesterol-Anchor Assembly of DNAzyme (ABCzyme) for Tumor Immunotherapy

Breakthroughs in immune checkpoint inhibitor (ICI) therapy have revolutionized clinical tumor therapy. Immunohistochemistry (IHC) analysis of PD-L1 in tumor tissue has been used to predict the response to tumor immunotherapy, but the results are not reproducible, and IHC is invasive and cannot be used to monitor the dynamic changes in PD-L1 expression during treatment. Monitoring the expression level of the PD-L1 protein on exosomes (exosomal PD-L1) is promising for both tumor diagnosis and tumor immunotherapy. Here, we established an aptamer-bivalent-cholesterol-anchor assembly of DNAzyme (ABCzyme) analytical strategy that can directly detect exosomal PD-L1 with a minimum lower limit of detection of 5.21 pg/mL. In this way, we found that the levels of exosomal PD-L1 are significantly elevated in the peripheral blood of patients with progressive disease. The precise analysis of exosomal PD-L1 by the proposed ABCzyme strategy provides a potentially convenient method for the dynamic monitoring of tumor progression in patients who receive immunotherapy and proves to be a potential and effective liquid biopsy method for tumor immunotherapy.

In vivo near-infrared fluorescence imaging of gastric cancer in an MKN-45 gastric cancer xenograft mouse model using intraoperative ureteral identification agent ASP5354

Accurate intraoperative identification of gastric cancer lesions and determination of the extent of resection are important for curability and function preservation. This study aimed to investigate the potential of the near-infrared fluorescence (NIRF) imaging agent ASP5354 for in vivo fluorescence imaging of gastric cancer. The capability of ASP5354 was evaluated using an MKN-45 human gastric cancer xenograft mouse model. A single dose of ASP5354 was intravenously administered to the mice at a concentration of 120 nmol (0.37 mg)/kg body weight. In vivo NIRF images of the mouse backs were obtained using an NIRF camera system. Moreover, the cancer tissues were dissected, and the NIRF intensity in the tissue sections was measured using the NIRF camera system. ASP5354 uptake in MKN-45 cells was assessed in vitro using the NIRF microscope. The NIRF signal of ASP5354 was selectively detected in gastric cancer tissues immediately after the intravenous administration of ASP5354. The cancer tissues emitted stronger NIRF signals than adjacent normal tissues. The difference in the NIRF intensity between the normal and cancer tissues was clearly observed at the boundary between them in the macrolevel NIRF images. Cancer tissues can be distinguished from normal tissues based on the measurement of the NIRF of ASP5354, using an NIRF camera system. ASP5354 is a promising agent for NIRF imaging of gastric cancer tissues.

Imaging of a novel ratio γ-glutamyl transpeptidase fluorescent probe in living cells and biopsies

Herein, a novel fluorescent probe, GTP, was developed for monitoring the GGT (γ-glutamyl transpeptidase) level in living cells and biopsies. It consisted of the typical recognition group γ-Glu (γ-Glutamylcysteine) and the fluorophore (E)-4-(4-aminostyryl)-1-methylpyridin-1-ium iodide. With a ratio response between the signal intensity at 560 nm and 500 nm (R_I560/_I500), it could be important complement for the turn-on ones. With the linear range of 0-50 U/L, the limit of detection was calculated as 0.23 μM. The detection system showed the strongest response near pH 7.4, and exhibited steady fluorescence signals for at least 48 h. With high selectivity, good anti-interference and low cytotoxicity, GTP was suitable for physiological applications. By monitoring the GGT level with the ratio values in the green and blue channels, the probe GTP could distinguish cancer cells from normal cells. Furthermore, in the mouse tissues and humanization tissue samples, the probe GTP could also recognize the tumor tissues from the normal ones.

Activatable dual-functional molecular agents for imaging-guided cancer therapy

Theranostics has attracted great attention due to its ability to combine the real-time diagnosis of cancers with efficient treatment modalities. Activatable dual-functional molecular agents could be synthesized by covalently conjugating imaging agents, therapeutic agents, stimuli-responsive linkers and/or targeting molecules together. They could be selectively activated by overexpressed physiological stimuli or external triggers at the tumor sites to release imaging agents and cytotoxic drugs, thus offering many advantages for tumor imaging and therapy, such as a high signal-to-noise ratio, low systemic toxicity, and improved therapeutic effects. This review summarizes the recent advances of dual-functional molecular agents that respond to various physiological or external stimuli for cancer theranostics. The molecular designs, synthetic strategies, activatable mechanisms, and biomedical applications of these molecular agents are elaborated, followed by a brief discussion of the challenges and opportunities in this field.

Development of an Au nanoclusters based activatable nanoprobe for NIR-II fluorescence imaging of gastric acid

Gastric acid is an important functional substance secreted by the stomach of the living organisms, reflecting the gastric physiological condition. The sensing of gastric acid in vivo is of great significance for evaluation of gastric function, diagnosis and treatment of gastric diseases and maintenance of organism health but remains challenging due to the harsh acid and digestive environment of stomach. This study developed an activatable nanoprobe based on Au nanoclusters (Au NCs) for sensitive and real-time noninvasive near-infrared II (NIR-II) fluorescence imaging detection of gastric acid in vivo for the first time. The Au NCs were encapsulated by polydopamine to have enhanced NIR-II luminescence and high stability and combined with methylene blue to possess the pH responsiveness for gastric acid imaging. The developed nanoprobe could not only monitor gastric acid secretion in vivo but also imaging the changes of gastric acid caused by feeding, acid-inhibition drugs and gastric ulcer disease. This study provides a promising avenue for the improvement of the application performance of Au NCs and imaging analysis of gastric acid and related gastric diseases.

Ultrasensitive Urinary Diagnosis of Organ Injuries Using Time-Resolved Luminescent Lanthanide Nano-bioprobes

Urinary sensing of synthetic biomarkers that are released into urine after specific activation in an in vivo disease environment is an emerging diagnosis strategy to overcome the insensitivity of a previous biomarker assay. However, it remains a great challenge to achieve sensitive and a specific urinary photoluminescence (PL) diagnosis. Herein, we report a novel urinary time-resolved PL (TRPL) diagnosis strategy by exploiting europium complexes of diethylenetriaminepentaacetic acid (Eu-DTPA) as synthetic biomarkers and designing the activatable nanoprobes. Notably, TRPL of Eu-DTPA in the enhancer can eliminate the urinary background PL for ultrasensitive detection. We achieved sensitive urinary TRPL diagnosis of mice kidney and liver injuries by using simple Eu-DTPA and Eu-DTPA-integrated nanoprobes, respectively, which cannot be realized by traditional blood assays. This work demonstrates the exploration of lanthanide nanoprobes for in vivo disease-activated urinary TRPL diagnosis for the first time, which might advance the noninvasive diagnosis of diverse diseases via tailorable nanoprobe designs.

Cytotoxicities of Tumor-Seeking Dyes: Impact on Future Clinical Trials

Heptamethine (Cy7) dyes with meso-Cl substituents injected intravenously (iv) into mice accumulate in tumors and persist there over several days. We believe this occurs via meso-Cl displacement by the only free cysteine residues of albumin; therefore, conjugating tumor-seeking dyes with fragments can increase selective therapeutic delivery to tumors and drug residence. This strategy has elevated significance recently because the first tumor-seeking dye-drug conjugate has moved into clinical trials. Options for further clinical research include modifying the dye, and use of preformed albumin adducts instead of dyes alone. Herein we show correlations of cytotoxicities, lipophilicities, organelle localization, apoptosis, cell-cycle arrest, wound healing/migration assays, and reactivities/affinities with human serum albumin are difficult to observe. However, our studies arrived at an important conclusion: preformed dye-drug-HSA adducts are less cytotoxic, and therefore preferable for subsequent clinical work, relative to direct injection of meso-Cl-containing forms.