Imaging of hydrogen peroxide (H2O2) during the ferroptosis process in living cancer cells with a practical fluorescence probe

A simple mitochondria-immobilized fluorescent probe for the detection of hydrogen peroxide

Hydrogen peroxide (H2O2), as one of reactive oxygen species (ROS) widely present in the human body, is involved in a variety of physiological activities. Many human diseases are associated with abnormal levels of H2O2 in the body. Mitochondria are the main organelles producing H2O2 in the human body, and monitoring the level of H2O2 in mitochondria can help to deepen the understanding of the detailed functions of H2O2 in physiological activities. However, due to the highly dynamic nature of the cells, real-time quantitative monitoring of H2O2 levels in mitochondria remains an ongoing challenge. Herein, a novel highly immobilized mitochondria-targeting fluorescent probe (QHCl) for detection of H2O2 was reasonably constructed based on quinolinium dye containing benzyl chloride moiety. Spectral experimental results demonstrated QHCl possessed outstanding selectivity toward H2O2 (λex/em = 380/513 nm). In addition, QHCl can quantitatively detect H2O2 in the concentration range of 0-20 μM with excellent sensitivity (LOD = 0.58 μM) under the PBS buffer solution (10 mM, pH = 7.4). Finally, bioimaging experiments demonstrated that the probe QHCl was able to be used for accurately detecting both endogenous and exogenous H2O2 in the mitochondria of living cells and zebrafish by its unique mitochondrial immobilization.

A novel near-infrared fluorescent probe for real-time monitoring of leucine aminopeptidase activity and metastatic tumor progression

This article discusses the importance of early tumor detection, particularly in liver cancer, and the role of leucine aminopeptidase (LAP) as a potential marker for liver cancer diagnosis and prognosis assessment. The article highlights the limitations of current tumor markers and the need for new markers and multi-marker approaches to improve accuracy. The authors introduce a novel near-infrared fluorescent probe, NTAP, designed for LAP detection. They describe the synthesis of the probe and evaluate its spectral properties, including the LOD was 0.0038 U/mL, and QY was 0.32 %. The kinetic properties of NTAP, such as the relationship between LAP concentration (0-0.08 U/mL), reaction time (3 min), and fluorescence excitation spectra (475 nm) and emission spectra (715 nm) are investigated. The article also discusses the stability and selectivity of the probe and its ability to detect LAP in complex samples. Cellular imaging experiments demonstrate the NATP specificity and selectivity in detecting LAP activity and its inhibition. Animal models of liver and lung metastasis are used to evaluate the probe's imaging capabilities, showing its ability to accurately locate and detect metastatic lesions. The article concludes by emphasizing the potential applications of the NTAP probe in early tumor diagnosis, treatment monitoring, and the study of tumor metastasis mechanisms.

A fluorescent probe for ultrarapid H2O2 detection during reagent-stimulated oxidative stress in cells and zebrafish

Hydrogen peroxide(H2O2), as a reliable signaling biomolecule for oxidative stress, its accurate detection during agent-stimulated oxidative stress plays a vital role in pathological and physiological mechanism exploration for disease theranostics. It's necessary to develop an efficient method for their detection. In view of the advantages of fluorescent probes, we rationally constructed a novel fluorescent probe Compound 2 based on 4-(Bromomethyl)benzeneboronic acid pinacol ester_Herein, a small molecule fluorescent probe was fabricated using isoflore nitrile as fluorescent group, phenylboronic acid pinacol ester as the response group, to detect H2O2. The probe Compound 2 has a strong fluorescence intensity at 575 nm, indicating that the structure of the probe molecule is reasonably designed, and the Stokes shift is up to 172 nm. While the detection time is as low as 30 s and the LOD of the probe for H2O2 is as low as 3.7 μmol/L,the quantum yield is Φ = 40.31 %. It has been successfully used for imaging detection of H2O2 in HepG2 cells and zebrafish for its low toxicity. It can be found that this small molecule fluorescent probe can identify H2O2 in tumor cells significantly and efficiently, which would realize the early diagnosis of tumor.

Unlocking ferroptosis in prostate cancer - the road to novel therapies and imaging markers

Ferroptosis is a distinct form of regulated cell death that is predominantly driven by the build-up of intracellular iron and lipid peroxides. Ferroptosis suppression is widely accepted to contribute to the pathogenesis of several tumours including prostate cancer. Results from some studies reported that prostate cancer cells can be highly susceptible to ferroptosis inducers, providing potential for an interesting new avenue of therapeutic intervention for advanced prostate cancer. In this Perspective, we describe novel molecular underpinnings and metabolic drivers of ferroptosis, analyse the functions and mechanisms of ferroptosis in tumours, and highlight prostate cancer-specific susceptibilities to ferroptosis by connecting ferroptosis pathways to the distinctive metabolic reprogramming of prostate cancer cells. Leveraging these novel mechanistic insights could provide innovative therapeutic opportunities in which ferroptosis induction augments the efficacy of currently available prostate cancer treatment regimens, pending the elimination of major bottlenecks for the clinical translation of these treatment combinations, such as the development of clinical-grade inhibitors of the anti-ferroptotic enzymes as well as non-invasive biomarkers of ferroptosis. These biomarkers could be exploited for diagnostic imaging and treatment decision-making.

Distinguishing the responsive mechanisms of fluorescent probes to hydrogen peroxide, proteins, and DNA/RNA

The responsive mechanisms of cationic quinolinium-vinyl-N,N-dimethylaniline boronate (QVD-B) derivative probes to hydrogen peroxide (H2O2), proteins and DNA/RNA are theoretically investigated in this study. The potential energy curves of QVD-B scanned on a dihedral angle (N+-C-CC) in the first singlet (S1) state exhibit large torsional energy barriers. Additionally, the energy of the lowest unoccupied molecular orbital (LUMO) of an acceptor moiety (-3.14 eV) is lower than that of a donor moiety (-1.13 eV) in QVD-B. This demonstrates that photoinduced electron transfer (PET) quenches the fluorescence of QVD-B, as opposed to the previous report of intramolecular single-bond rotation. After reacting with H2O2, the reaction product of quinoline-vinyl-N,N-dimethylaniline (QVD) turns off the PET pathway and turns on the fluorescence at 550 nm, which is consistent with the experimental results (580 nm). Among the possible configurations of QVD-B that forms with proteins and DNA, the calculated fluorescence values of corresponding twisted QVD-B-P (638 nm) and QVD-B-D (686 nm) are consistent with the experimental results (632 and 688 nm). The frontier molecular orbital and electron-hole analysis show that the charge transfer distance follows the order of QVD (1.88 Å) < QVD-B-P (4.49 Å) < QVD-B-D (6.39 Å), which induces the fluorescence red-shifts of QVD-B-P and QVD-B-D compared to that of QVD. The multi-detection mechanism of the fluorescent probe QVD-B is attributed to PET progress and different degrees of local charge transfer after photoexcitation.

Ferroptosis-Based Therapeutic Strategies toward Precision Medicine for Cancer

Ferroptosis is a type of iron-dependent programmed cell death characterized by the dysregulation of iron metabolism and the accumulation of lipid peroxides. This nonapoptotic mode of cell death is implicated in various physiological and pathological processes. Recent findings have underscored its potential as an innovative strategy for cancer treatment, particularly against recalcitrant malignancies that are resistant to conventional therapies. This article focuses on ferroptosis-based therapeutic strategies for precision cancer treatment, covering the molecular mechanisms of ferroptosis, four major types of ferroptosis inducers and their inhibitory effects on diverse carcinomas, the detection of ferroptosis by fluorescent probes, and their implementation in image-guided therapy. These state-of-the-art tactics have manifested enhanced selectivity and efficacy against malignant carcinomas. Given that the administration of ferroptosis in cancer therapy is still at a burgeoning stage, some major challenges and future perspectives are discussed for the clinical translation of ferroptosis into precision cancer treatment.

ONOO- Activatable Fluorescent Sulfur Dioxide Donor for a More Accurate Assessment of Cell Ferroptosis

Ferroptosis is critical in the treatment of tumor therapies. Thus, monitoring reactive oxygen species (ROS) is of great significance for accurate assessment in ferroptosis without any interference. However, current probes for monitoring ROS during ferroptosis suffer from a drawback in that the probes consume ROS during detection, which inhibits the ferroptosis process and thus affects the accuracy and effectiveness of monitoring the process of ferroptosis. Herein, a new fluorescent donor probe, TFMU-SO2D, with the combination of the moiety of the SO2 donor is designed and synthesized by introducing the aryl boronate moieties that could give it the ability to effectively recognize ONOO-. The released SO2 could consume excess glutathione and regulate oxidative stress by elevating ROS levels, which would offset the ROS depletion by TFMU-SO2D and ensure accuracy in monitoring the ferroptosis process. The experimental results demonstrated that TFMU-SO2D possessed satisfactory performance for monitoring ONOO- as well as simultaneously releasing SO2 in oxidative stress stimulated by monensin and ferroptosis stimulated by erastin and RSL3. Additionally, the capability of SO2 synergized with ferroptosis to inhibit the viability of cancer cells was demonstrated by the CCK8 assay, which may be due to the fact that SO2 can potentiate ferroptosis cell death by increasing the ROS level. Overall, these combined results indicated that TFMU-SO2D possesses the excellent ability to precisely monitor ONOO- during ferroptosis without interference, which is significant for accurately accessing ferroptosis, cancer treatment, and drug development.

Tumor microenvironment responsive nano-platform for overcoming sorafenib resistance of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a malignant tumor, which seriously jeopardizes human health. The 5-year relative survival rate of HCC is only about 18%. Sorafenib, a small molecule multi-targeted tyrosine kinase inhibitor (MTKI), has been classified as the first-line treatment scheme for HCC and has significantly extended the median survival time for patients with advanced HCC. Nevertheless, the emergence of sorafenib resistance has substantially hampered its further clinical application. Herein, the nano-platform based on phototherapy and small molecular targeted therapy (SMTT) was devised to overcome the sorafenib resistance and reduce the adverse effects. Hollow mesoporous manganese dioxide (H-MnO2) was prepared by hard template method, and the prepared H-MnO2 was used to load sorafenib and Chlorin e6 (Ce6). Subsequently, the nanoparticle (NPs) were modified with dopamine to optimize biocompatibility. The final prepared NPs (MCS NPs) exhibit regular spherical shape with a hydrated particle size of approximately 97.02 nm. MCS NPs can not only possess tumor microenvironment (TME) stimuli-responsive drug release performance but also can enhance the efficacy of photodynamic therapy and reverse sorafenib resistance by alleviating tumor hypoxia. Under the action of phototherapy (Ce6) combined with molecular targeted therapy (sorafenib), MCS NPs manifest a satisfactory antitumor effect for sorafenib-sensitive or sorafenib-resistant HCC cells, and retain the antiangiogenic properties of sorafenib. In the nude mouse subcutaneous tumor model constructed with sorafenib-resistant cells, MCS NPs demonstrated superior tumor imaging ability and excellent biocompatibility. The tumor inhibition rate of the MCS NPs group without laser irradiation was 53.4 %, while the MCS NPs group with laser irradiation was as high as 100 %. The novel smart TME-responsive nano-platform shows great potential for overcoming sorafenib resistance and realizes multimodality imaging and therapy of HCC.

Role of mitochondria in the regulation of ferroptosis and disease

Ferroptosis is a distinctive form of iron-dependent cell death characterized by significant ultrastructural changes in mitochondria. Given the crucial involvement of mitochondria in various cellular processes such as reactive oxygen species production, energy metabolism, redox status, and iron metabolism, mounting evidence suggests a vital role of mitochondria in the regulation and execution of ferroptosis. Furthermore, there exists a strong correlation between ferroptosis and various diseases. In this review, we aim to summarize the mechanisms underlying the induction and defense of ferroptosis, emphasizing the influence of mitochondria on this intricate process. Additionally, we provide an overview of the role of ferroptosis in disease, particularly cancer, and elucidate the mechanisms by which drugs targeting mitochondria impact ferroptosis. By presenting a theoretical foundation and reference point, this review aims to contribute to both basic cell biology research and the investigation of clinically relevant diseases.

Migration from Lysosome to Nucleus: Monitoring Lysosomal Alkalization-Related Biological Processes with an Aminofluorene-Based Probe

Aberrant lysosomal alkalization is associated with various biological processes, such as oxidative stress, cell apoptosis, ferroptosis, etc. Herein, we developed a novel aminofluorene-based fluorescence probe named FAN to monitor the lysosomal alkalization-related biological processes by its migration from lysosome to nucleus. FAN possessed NIR emission, large Stokes shift, high pH stability, and high photostability, making it suitable for real-time and long-term bioimaging. As a lysosomotropic molecule, FAN can accumulate in lysosomes first and then migrate to the nucleus by right of its binding capability to DNA after lysosomal alkalization. In this manner, FAN was successfully used to monitor these physiological processes which triggered lysosomal alkalization in living cells, including oxidative stress, cell apoptosis, and ferroptosis. More importantly, at higher concentrations, FAN could also serve as a stable nucleus dye for the fluorescence imaging of the nucleus in living cells and tissues. This novel multifunctional fluorescence probe shows great promise for application in lysosomal alkalization-related visual research and nucleus imaging.

Fluorescent probes for ferroptosis bioimaging: advances, challenges, and prospects

Ferroptosis is a form of regulatory cell death distinct from caspase-dependent apoptosis and plays an important role in life entities. Since ferroptosis involves a variety of complex regulatory factors, the levels of certain biological species and microenvironments would change during this process. Thus, the investigation of the level fluctuation of key target analytes during ferroptosis is of great significance for disease treatment and drug design. Toward this aim, multiple organic fluorescent probes with simple preparation and non-destructive detection have been developed, and research over the past decade has uncovered a vast array of homeostasis and other physiological characteristics of ferroptosis. However, this significant and cutting-edge topic has not yet been reviewed. In this work, we aim to highlight the latest breakthrough results of fluorescent probes for monitoring various bio-related molecules and microenvironments during ferroptosis at the cellular, tissue and in vivo levels. Accordingly, this tutorial review has been organized according to the target molecules identified by the probes including ionic species, reactive sulfur species, reactive oxygen species, biomacromolecules, microenvironment, and others. In addition to providing new insights into the findings of each fluorescent probe in ferroptosis studies, we also discuss the defects and limitations of the probes developed, and highlight the potential challenges and further prospects in this domain. We anticipate that this review will convey profound implications for designing powerful fluorescent probes to decrypt changes in key molecules and microenvironments during ferroptosis.

Bioinorganic Modulators of Ferroptosis: A Review of Recent Findings

Ferroptosis was first reported as a separate modality of regulated cell death in 2008 and distinguished under its current name in 2012 after it was first induced with erastin. In the following decade, multiple other chemical agents were researched for their pro- or anti-ferroptotic properties. Complex organic structures with numerous aromatic moieties make up the majority of this list. This review fills a more overlooked niche by gathering, outlining and setting out conclusions regarding less prominent cases of ferroptosis induced by bioinorganic compounds and reported on within the last few years. The article contains a short summary of the application of bioinorganic chemicals based on gallium, several chalcogens, transition metals and elements known as human toxicants used for the purpose of evoking ferroptotic cell death in vitro or in vivo. These are used in the form of free ions, salts, chelates, gaseous and solid oxides or nanoparticles. Knowledge of how exactly these modulators promote or inhibit ferroptosis could be beneficial in the context of future therapies aimed against cancer or neurodegenerative diseases, respectively.

Recent advances in small-molecule fluorescent probes for studying ferroptosis

Ferroptosis is an iron-dependent, non-apoptotic form of programmed cell death driven by excessive lipid peroxidation (LPO). Mounting evidence suggests that the unique modality of cell death is involved in the development and progression of several diseases including cancer, cardiovascular diseases (CVDs), neurodegenerative disorders, etc. However, the pathogenesis and signalling pathways of ferroptosis are not fully understood, possibly due to the lack of robust tools for the highly selective and sensitive imaging of ferroptosis analytes in complex living systems. Up to now, various small-molecule fluorescent probes have been applied as promising chemosensors for studying ferroptosis through tracking the biomolecules or microenvironment-related parameters in vitro and in vivo. In this review, we comprehensively reviewed the recent development of small-molecule fluorescent probes for studying ferroptosis, with a focus on the analytes, design strategies and bioimaging applications. We also provided new insights to overcome the major challenges in this emerging field.

A novel hydrogen peroxide fluorescent probe for bioimaging detection and enables multiple redox cycles

In this subject, a novel hydrogen peroxide (H₂O₂) fluorescent probe (MNG) was designed and developed using naphthalimide derivatives and selenomorpholine. In PBS buffer (10 mM, pH = 7.4, 1 %DMSO), the selenomorpholine on the probe is capable of qualitatively and quantitatively detecting (H₂O₂) at a small amount under a detection limit of 61 nM. The probe follows a mechanism that Se (Ⅱ) in selenomorpholine is transformed to Se (Ⅳ), thus changing the spectra of the probe MNG. It is noteworthy that MNG can continuously make a cyclic response to H₂O₂ and glutathione (GSH), so it can potentially achieve redox process imaging in vivo. Moreover, this subject verified the redox process of the probe's continuous redox response in the Gaussian 09 programme through simulation calculation and mass spectrometry. The probe exhibits high biocompatibility. Moreover, it can detect H₂O₂ in MCF-7 cells and Argentine Bloodfin.

Mitochondrial-Targeted Ratiometric Fluorescent Probe to Monitor ClO- Induced by Ferroptosis in Living Cells

Ferroptosis is a type of iron-dependent programmed cell death. Once such kind of death occurs, an individual cell would undergo a series of changes related to reactive oxygen species (ROS) in mitochondria. A mitochondrial-targeted ratiometric fluorescent probe (MBI-OMe) was developed to specifically detect ferroptosis-induced ClO⁻, whose recognition group is p-methoxyphenol, and the mitochondrial-targeted group is benzimidazole. The fluorescence of MBI-OMe was first quenched by 30 μM of Fe³⁺, and then MBI-OMe appeared as a ratiometric signal at 477 nm and 392 nm in response to ferroptosis-induced ClO⁻ in living cells. MBI-OMe was successfully used to evaluate changes in ClO⁻ induced by ferroptosis.

Recent Advances of Fluorescence Probes for Imaging of Ferroptosis Process

Ferroptosis is an iron−dependent form of regulated cell death. It has attracted more and more research interests since it was found because of its potential physiological and pathological roles. In recent years, many efforts have been made for the developments and applications of selective fluorescence probes for real−time and in situ tracking of bioactive species during ferroptosis process, which is necessary and significant to further study the modulation mechanisms and pathological functions of ferroptosis. In this review, we will focus on summarizing the newly developed fluorescence probes that have been applied for ferroptosis imaging in the recent years, and comprehensively discussing their design strategies, including the probes for iron, reactive oxygen species, biothiols and intracellular microenvironmental factors.

Photoelectrochemical sensing and mechanism investigation of hydrogen peroxide using a pristine hematite nanoarrays

In this paper, a facile hydrothermal combined with subsequent two-step post-calcination method was used to fabricate hematite (α-Fe₂O₃) nanoarrays on fluorine-doped SnO₂ glass (FTO). The morphology, crystalline phase, optical property and surface chemical states of the fabricated α-Fe₂O₃ photoelectrode were characterized by scanning electron microscopy, X-ray diffraction, ultraviolet visible spectroscopy and X-ray photoelectron spectroscopy correspondingly. The α-Fe₂O₃ photoelectrode exhibits excellent photoelectrochemical (PEC) response toward hydrogen peroxide (H₂O₂) in aqueous solutions, with a low detection limit of 20 μM (S/N = 3) and wide linear range (0.01-0.09, 0.3-4, and 6-16 mM). Additionally, the α-Fe₂O₃ photoelectrode shows satisfying reproducibility, stability, selectivity and good feasibility for real samples. Mechanism analysis indicates, comparing with H₂O, H₂O₂ possesses much more fast reaction kinetics over α-Fe₂O₃ surface, thus the recombination of photogenerated charges are reduced, followed by much more photogenerated electrons are migrated to the counter electrode via external circuit. The insight on the enhanced photocurrent, which is corelative to the concentration of H₂O₂ in aqueous solution, will stimulate us to further optimize the surface structure of α-Fe₂O₃ to gain highly efficient α-Fe₂O₃ based sensors.

A "turn-on" fluorescent probe with high selectivity and large stokes shift for the detection of hydrogen peroxide and its bioimaging applications

Hydrogen peroxide (H₂O₂) plays pivotal roles in various biological functions and pharmacological activities. High selectivity and sensitivity remain challenges for fluorescent probes to detection of H₂O₂ with a large stokes shift. Herein, a new "turn-on" fluorescent probe (DCM-C) was designed based on the mechanism of intramolecular charge transfer (ICT). In PBS buffer (10 mM, pH 7.4, with 20% DMSO, v/v), DCM-C exhibited high selectivity and sensitivity for H₂O₂ over other interfering analytes with a large stokes shift (187 nm), and the detection limit was as low as 35.5 nM. In addition, the probe was effective for detecting exogenous and endogenous H₂O₂ in living cells, and identifying stained in cytoplasm. Moreover, the probe has been used successfully for determining H₂O₂ in zebrafish by fluorescence imaging.

Carbon dot based nucleus targeted fluorescence imaging and detection of nuclear hydrogen peroxide in living cells

Investigation of the intracellular generation of H₂O₂, one of the most important reactive oxygen species (ROS), is crucial for preventing various diseases since it is closely linked with different physiological and complex cell signaling pathways. Despite the development of various fluorescent probes, the majority of the fluorescent probes cannot move across the nuclear membrane. However, detection of the nuclear level of H₂O₂ is very important since it can directly cause oxidative DNA damage which ultimately leads to various diseases. Therefore, in this study, p-phenylenediamine based carbon quantum dots (B-PPD CDs) have been synthesized and integrated with 4-formylbenzeneboronic acid as a doping agent for the detection of H₂O₂. The detection mechanism showed that, upon exposure to H₂O₂, the fluorescence of the B-PPD CDs was immediately quenched. Further investigation has been done in the in vitro RAW 264.7 cell line by both exogenous and endogenous exposure of H₂O₂ to demonstrate the feasibility of the method. It is shown successfully that the exogenous presence and endogenous generation of H₂O₂ in RAW 264.7 cells can be detected using B-PPD CDs. The limit of detection (LOD) was determined to be 0.242 μM. The development of such imaging probes using carbon quantum dots will lead to live-cell imaging as well as ROS detection.

A novel fluorescent probe for the detection of peroxynitrite and its application in acute liver injury model

Realizing the early diagnosis of acute liver injury has become a hotspot in recent years. Since the current indexes are not specific, developing novel probes with new recognition group remains a necessity. In this work, we developed a novel fluorescent probe, NNP, for the detection of ONOO⁻ in acute liver injury (ALI). The in vitro evaluation of NNP indicated the advantages including high sensitivity (LOD = 0.13 μM), rapid response (<25 s), naked-eye (red to yellow), and stability under various pH (4–10) and time (>48 h) conditions. Accordingly, NNP achieved the dose-dependent detection of ONOO⁻ in human hepatic stellate LX-2 cells. Further, in the ALI model mice, NNP could monitor the ONOO⁻ level in the occurrence of ALI in situ (in the liver region) with a steady performance. Subsequent immunohistochemical and imaging studies confirmed that NNP could achieve the detection of endogenous ONOO⁻ in ALI liver tissues. This work introduced a practical implement for the ONOO⁻ detection in ALI as well as a referable example for the establishment of molecular indexes in pre-clinical diagnosis.

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A novel fluorescent probe, NNP, for the detection of ONOO⁻ in acute liver injury model.

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High sensitivity, high selectivity, rapid response and steadiness for over 48 h.

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Applications in human hepatic stellate cell line for cellular imaging of ONOO⁻ level.

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Achieving the detection of endogenous ONOO⁻ in mice and liver tissues.

A biotin-guided two-photon fluorescent probe for detection of hydrogen peroxide in cancer cells ferroptosis process

Hydrogen peroxide (H₂O₂) plays a vital role in organism due to its strong oxidizability, especially in resisting the invasion of pathogens. Cancer cells have abnormal concentrations of hydrogen peroxide due to their disordered reproduction. In complex biological systems, however, conventional fluorescent probes based solely on their fluorescent response to abnormal H₂O₂ overexpression in cancer cells are not enough to distinguish cancer cells from other unhealthy or immune cells. Therefore, it is necessary to develop other methods to allow the probe to selectively enter the cancer cells and perform fluorescence imaging of the hydrogen peroxide in the cancer cells. Herein, we developed a biotin-guided, two-photon fluorescent probe (BT-HP) for sensitive detection of H₂O₂ in cancer cells. Through the study on the properties of the probe, it was found that the probe can selectively enter cancer cells. The depth penetration imaging of H₂O₂ in cancer cells and tumor tissues by two-photon microscope proves the potential of the probe BT-HP as a tumor targeting H₂O₂ biosensor. The probe was further applied to detect hydrogen peroxide in cancer cells during the ferroptosis process.

Stimuli-Responsive Multifunctional Phenylboronic Acid Polymers Via Multicomponent Reactions: From Synthesis to Application

Stimuli-responsive polymers undergo changes under different environmental conditions. Among them, phenylboronic acid (PBA) containing polymers (PBA-polymers) are unique, because they can selectively react with diols to generate borates that are sensitive to pH, sugars, and H₂ O₂ , and can be effectively used to synthesize smart drug carriers and self-healing hydrogels. Recently, multifunctional PBA-polymers (MF-PBA-polymers) have been developed using multicomponent reactions (MCRs) to introduce PBA groups into polymer structures. These MF-PBA-polymers have features similar to those of traditional PBA-polymers; moreover, they exhibit additional properties, such as fluorescence, antimicrobial activity, and antioxidant capability, when different MCRs are used. In this mini review, the preparation of these MF-PBA-polymers are summarized and the new properties/functions that have been introduced into these polymers using different MCRs are discussed. The uses of these MF-PBA-polymers as fluorescent cell anticoagulants, drug carriers, and gelators of functional self-healing hydrogels have been discussed. Additionally, the challenges encountered during their preparation are discussed and also the future developments in this field are touched upon.

Designing an ESIPT-based fluorescent probe for imaging of hydrogen peroxide during the ferroptosis process

Hydrogen peroxide (H₂O₂), depending on its levels, plays a crucial role in either modulating various biological processes as a signal molecule, or mediating oxidative damage as a toxin. Therefore, monitoring intracellular H₂O₂ levels is pivotal for exploring its physiological and pathological roles. Using a modified 2-(2'-hydroxyphenyl) benzothiazole (HBT) as the fluorophore, and a pinacol phenylborate ester as the responsive group, herein we developed an excited-state intramolecular proton transfer (ESIPT)-based probe BTFMB. The probe exhibited turn-on fluorescence response, large Stokes shift (162 nm) and low detection limit (109 nM) toward H₂O₂, and was successfully applied for monitoring exogenous and endogenous production of H₂O₂, and identifying accumulation of H₂O₂ during the ferroptosis process.

Nanostructured manganese dioxide for anticancer applications: preparation, diagnosis, and therapy

Nanostructured manganese dioxide (MnO₂) has attracted extensive attention in the field of anticancer applications. As we all know, the tumor microenvironment is usually characterized by a high glutathione (GSH) concentration, overproduced hydrogen peroxide (H₂O₂), acidity, and hypoxia, which affect the efficacy of many traditional treatments such as chemotherapy, radiotherapy, and surgery. Fortunately, as one kind of redox-active nanomaterial, nanostructured MnO₂ has many excellent properties such as strong oxidation ability, excellent catalytic activity, and good biodegradability. It can be used effectively in diagnosis and treatment when it reacts with some harmful substances in the tumor site. It can not only enhance the therapeutic effect but also adjust the tumor microenvironment. Therefore, it is necessary to present the recent achievements and progression of nanostructured MnO₂ for anticancer applications, including preparation methods, diagnosis, and treatment. Special attention was paid to photodynamic therapy (PDT), bioimaging and cancer diagnosis (BCD), and drug delivery systems (DDS). This review is expected to provide helpful guidance on further research of nanostructured MnO₂ for anticancer applications.

A new chloro-substituted dicyanoisophorone-based near-infrared fluorophore with a larger Stokes shift and its application for detecting cysteine in cells and in vivo

Many dicyanoisophorone-based fluorophores with an optical hydroxyl group have been explored to meet different imaging needs along with the rapid and wide development of molecular fluorescence bioimaging in recent years.