Domino-like turn-on chemiluminescence amplification: Opening a gateway through proximal-imidazole species formation and metal-ligand complexation

Due to their extremely low background signal and high sensitivity, the chemiluminescence (CL) probes have received a great attention in various chemical and biological applications. However, the lack of selectivity is still a challenging task. As an innovative topic of research, in this work we developed a domino-like turn-on CL reaction through proximal-imidazole species for the first time. The oxidation reaction of N-(2H-[1,2,4]thiadiazolo[2,3-a]pyridine-2-ylidene)benzamide (1) by hydrogen peroxide found to promoted by a domino-like reaction between proximal imidazole species and the Co2+-1 complex formation which accompanied by a dramatically turn-on emission. In the way of explaining the possible mechanism, the application of density functional theory (DFT) studies revealed that there are three possible pathways for the reactions between precursor 1 and HOO- in the presence of imidazole to produce the oxidized isomers. The strongest interaction found to occur in pathway 3, in which the sulfur atom was oxidized, while there was some repulsion between HOO- and 1, due to the effects of two different charges in pathways 1 and 2. To confirm tits applicability, the CL system was successfully applied to highly selective quantification of vitamin B12 in some real samples. The linear dynamic range was achieved from 0.08 to 34 ng mL-1 and the detection limit was evaluated as 0.028 ng mL-1. This new method introduced fluorescence selectivity and CL sensitivity in single technique. It was finally anticipated that the CL amplification through proximal-imidazole species possesses a great potential on tuning various color-emissions based on different metal-ligand complex formations studied.

Surface-Defect-Involved Chemiluminescence Boosted by Gold-Silver Bimetallic Nanoclusters for Bioanalysis

Chemiluminescence (CL) as a powerful analytical tool has garnered increasing interest. However, traditional molecular-based CL luminophores suffer from low emission efficiency due to limited total CL photons emitted per luminophore, driving efforts to explore amplified strategies or novel probes to boost the emission. Although metal nanoclusters (NCs) as luminescent nanoprobes have been extensively studied for electrochemiluminescence and photoluminescence (PL) owing to their intriguing luminescent properties, the CL performance using metal NCs as emitters is often ignored. Herein, based on the synergistic effect within the bimetallic NCs, a series of glutathione-coated Au-Ag bimetallic NCs (GSH-AuAg NCs) were optimized by adjusting precursor ratios and achieved the maximum CL response at a Au:Ag molar ratio of 5:1. To our surprise, CL emission with GSH-AuAg NCs as emitters was triggered with oxidant reagents such as KMnO4, and bimetallic NCs display boosted CL emission (ca. 6.2-fold) compared to monometallic NCs owing to the synergistic effect on enhancing the emission efficiency. Surface-defect-involved CL was revealed by collecting the CL spectra with a maximum emission wavelength of around 750 nm and an obvious red shift of 140 nm compared to PL spectra. The mechanism reveals the KMnO4-injected hole into the valence band through redox reactions with GSH ligands, leading to CL emission by efficient radiative charge recombination with pre-existing electron. A sensing platform based on the GSH-AuAg NCs/oxidant system was constructed for sensing H2O2 and glucose, demonstrating the potential of GSH-AuAg NCs as CL emitters in analytical applications.

Ultrasensitive chemiluminescence detection based on titanium-doped spinel-structured nanoparticles with abundant oxygen vacancies

We successfully synthesized spinel-structured ternary nanocatalyst Ti-Co3O4/Fe3O4 nanoparticles (NPs) for the first time. Ti-Co3O4/Fe3O4 NPs exhibited superior catalytic performance compared to the synthesized binary catalysts Co3O4/Fe3O4. Moreover, Ti-Co3O4/Fe3O4 NPs can enhance the chemiluminescence (CL) intensity of the luminol/H2O2 system by over 3800-fold, attributed to the high density of oxygen vacancies (OVs) within the structure. OVs contribute to electron delocalization, improve conductivity, and are recognized as crucial active sites in the catalytic decomposition of H2O2. Based on the inhibitory effect of L-ascorbic acid (AA) on the luminol/H2O2 CL system, we developed a sensitive, rapid, effective, and highly selective AA CL assay with a linear range of 0.1 μmol/L to 100 μmol/L and a limit of detection (LOD, S/N = 3) of 0.044 μmol/L. The method was successfully applied to quantify AA in vitamin C tablets with recoveries ranging from 99.7 % to 106.3 %. This research provides a promising prospect for the application of spinel-structured nanoparticles in CL detection platforms and offers valuable insights into nanoparticle size modulation and OV engineering for catalytic optimization.

Persistent Chemiluminescence-Enabled Digital Bead Counting for Quantifying Attomolar MicroRNAs

Digital biosensing is the state-of-the-art technique for precisely quantifying low-abundance biomarkers but heavily limited to sophisticated fabrication of sealed microchambers and fluorescence signal readout. Herein, a novel persistent, enhanced-chemiluminescence (E-CL)-enabled microchamber-free digital counting strategy is proposed for miRNA analysis by using fully open microbeads (MBs) as independent microreactors and signaling units. The employment of a phenothiazine derivative enhancer efficiently transfers the flash-type CL of horseradish peroxidase (HRP)-H2O2-luminol into persistent and stable E-CL with more than 103-fold signal enhancement. More importantly, by leveraging single miRNA molecule-activated deposition of HRP, the driving power of E-CL, on the miRNA-loaded MBs, the long-lasting E-CL can be finely sustained on the MBs' surface, achieving CL-based binary MB counting for digital miRNA quantification at the aM level. This persistent E-CL-powered microchamber-free digital design may well complement prevalent fluorescence-based digital bioassays by effectively addressing their inherent drawbacks (photobleaching/quenching and scattering light background), thus expanding the digital biosensing toolbox.

ROS-Responsive Fluorinated Oxalate Nanomedicine for Dual Chemiluminescence/1⁹F MRI Imaging and Targeted Drug Release

In this study, we developed a novel theranostic nanomedicine formulation that integrates multimodal imaging with controlled drug release in reactive oxygen species (ROS)-rich microenvironments. A fluorinated oxalate compound (FOC) was synthesized through a one-step condensation reaction between 1,1,1,3,3,3-hexafluoro-2-propanol and oxalyl chloride, characterized by 1H, 13C, and 1⁹F NMR spectroscopy. The FOC and luminophore-incorporated nanomedicine formulations reacted rapidly with hydrogen peroxide via the peroxyoxalate chemiluminescence (POCL) mechanism, producing strong chemiluminescence and inducing a notable 19-fold increase in ratiometric 1⁹F NMR signal upon conversion to fluorinated alcohol (FAH), demonstrating promising potential for high-contrast 1⁹F MRI in deep tissue. Following ROS stimulation, the chemical conversion from hydrophobic FOC to hydrophilic FAH led to the degradation of the nanomedicines, facilitating payload release. In vitro experiments with A-431 cancer cells under hypoxic conditions confirmed ROS-responsive drug release, evidenced by enhanced fluorescence from model luminophores. Additionally, doxorubicin-loaded FOC nanomedicines reduced cell viability to 32% under hypoxia while remaining non-toxic in normoxic conditions. These results indicate that FOC-based nanomedicine formulations provide a promising platform for combined chemiluminescence and 1⁹F MRI with targeted therapeutic efficacy in ROS-rich inflammatory and cancerous tissues.

Aerobic oxidation catalyst vanadyl acetylacetonate boosts luminol chemiluminescence for sensitive detection of alkaline phosphatase and ascorbic acid

Vanadyl acetylacetonate, VO(acac)2, is a well-known environmentally friendly catalyst for aerobic oxidations. It has been exploited as an efficient co-reactant of luminol chemiluminescence (CL) in aqueous media for the first time. The luminol-VO(acac)2 system generates an intense CL and ascorbic acid can quench its CL remarkably. Based on the strong quenching effect of ascorbic acid, the luminol-VO(acac)2 CL was used in the quantification of clinically important ascorbic acid and alkaline phosphatase (ALP) by enzymatic conversion of L-ascorbic acid 2-phosphate into ascorbic acid. The linear ranges for detecting ascorbic acid and alkaline phosphatase are 1 to 100 μM and 0.005 to 200 U/L, respectively. The limits of detection of ascorbic acid and alkaline phosphatase are 0.5 μM and 0.005 U/L, respectively. The proposed CL method has shown high selectivity for the ALP among the tested biomolecules and metal ions. It also shows good recoveries in human serum samples.

Present and future of smartphone-coupled chemiluminescence and electrochemiluminescence assays: a mini-review

The convergence of smartphones with chemiluminescence and electrochemiluminescence (CL/ECL) assays marks a transformative leap in the realm of sensing technologies. The traditional CL/ECL assays, known for their high sensitivity and versatility, find extensive applications in medical diagnostics, environmental monitoring, food safety, and forensic sciences. However, these techniques have long been constrained due to the requirement of expensive instrumentation and complex reagent handling and hence their accessibility within certain environments is limited. In an era where rapid, accurate, and routine analysis is critical, smartphone-enabled CL/ECL systems offer substantial advantages over conventional analytical methods. By leveraging the universal accessibility and technological sophistication of smartphones and combining them with CL/ECL-based sensing, the smartphone has evolved into a cost-efficient and accessible analytical platform. The ability of the combined platform to conduct on-site analysis in real-time with minimal effort has emerged as a game-changer, particularly in low-resource settings. This mini-review explores the rapid evolution of smartphone-coupled CL/ECL systems over the last five years. The article covers the areas where the combined platform has been implemented in recent years for various sensing applications. The review further identifies key challenges that are associated with such combined platforms and finally highlights the future perspectives of the present topic.

Enhanced Chemiluminescence Induced by Natural Light-Driven MIL-100(Fe)/TiO2 for Dopamine Detection

Luminol-based chemiluminescence (CL) systems, as a powerful tool for bioanalysis, are limited owing to their weak CL intensity and self-decomposition of the classic oxidant H2O2. Herein, we introduced a new luminol CL enhancer, the natural light-driven photocatalyst MIL-100(Fe)/TiO2, for the selective determination of dopamine (DA). By employing MIL-100(Fe)/TiO2 for the first time as an efficient enhancer, the MIL-100(Fe)/TiO2-luminol CL intensity was 100 times higher than that of the classical H2O2-luminol system. The CL spectrum, UV-vis absorption spectroscopy, radical scavenger experiments, and electron spin resonance spectroscopy were utilized to investigate the possible CL mechanism of the MIL-100(Fe)/TiO2-luminol system. All of the results indicated that MIL-100(Fe)/TiO2 can generate reactive oxygen species under mild natural light, which could react rapidly with the luminol anion radical and result in direct CL emission. The sensitive plate for DA was developed based on its inhibiting effect on CL intensity, and the linear range between CL intensity and DA concentration was 100 nM-1000 μM with a detection limit of 16.7 μM (S/N = 3). This study successfully achieved a stable reactant that can directly trigger the CL of luminol without the need for additional oxidizing agents under mild natural light and offers new possibilities for photoinduced amplification technology.

Near-Infrared Chemiluminescent Theranostics

Molecular chemiluminescence probes with near-infrared (NIR) emission offer promising benefits in deciphering complex pathological processes in a living system, as NIR chemiluminescence minimizes autofluorescence, enhances deep-tissue penetration, and improves signal-to-noise ratio. Molecular engineering using single-luminophore design and dual-luminophore design with intramolecular energy transfer provides ways to develop conventional chemiluminophore scaffolds into NIR chemiluminescence probes with ideal chemiluminescence quantum yield and half-life. By virtue of the structural diversity, 1,2-dioxetane-based NIR chemiluminophores with biomarker activity have been developed. This review summarizes the molecular design strategies of NIR chemiluminescence theranostic probes (NCTPs), followed by introducing activatable NCTPs with their biomedical applications for disease theranostics. Lastly, future perspectives and potential challenges of NIR chemiluminescence imaging in preclinical research and clinical translational potential are discussed.

Recent Advances on Integrating Porous Nanomaterials with Chemiluminescence Assays

Advanced porous nanomaterials have recently been the subject of considerable interest due to their high surface areas, tunable pore structures, high porosity, and ease of modification. In the chemiluminescence (CL) domain, the incorporation of additional pores into nanostructures not only enhances the loading capacity for signal amplification but also allows the confinement effect in a nanoscale microreactor and the controlled release of reaction agents. In light of this, increasing efforts have been made to fabricate various porous nanomaterials and explore their potential applications in CL assays. This review therefore aims to highlight the recent advances in preparation strategies and basic attributes of the CL-related porous nanomaterials. Moreover, it offers a comprehensive summary of the emerging CL sensing applications based on these materials. The key challenges and future perspectives of porous nanomaterials in CL assays are finally discussed.

Deep Learning-Enhanced Chemiluminescence Vertical Flow Assay for High-Sensitivity Cardiac Troponin I Testing

Democratizing biomarker testing at the point-of-care requires innovations that match laboratory-grade sensitivity and precision in an accessible format. Here, high-sensitivity detection of cardiac troponin I (cTnI) is demonstrated through innovations in chemiluminescence-based sensing, imaging, and deep learning-driven analysis. This chemiluminescence vertical flow assay (CL-VFA) enables rapid, low-cost, and precise quantification of cTnI, a key cardiac protein for assessing heart muscle damage and myocardial infarction. The CL-VFA integrates a user-friendly chemiluminescent paper-based sensor, a polymerized enzyme-based conjugate, a portable high-performance CL reader, and a neural network-based cTnI concentration inference algorithm. The CL-VFA measures cTnI over a broad dynamic range covering six orders of magnitude and operates with 50 µL of serum per test, delivering results in 25 min. This system achieves a detection limit of 0.16 pg mL-1 with an average coefficient of variation under 15%, surpassing traditional benchtop analyzers in sensitivity by an order of magnitude. In blinded validation, the computational CL-VFA accurately measures cTnI concentrations in patient samples, demonstrating a robust correlation against a clinical-grade FDA-cleared analyzer. These results highlight the potential of CL-VFA as a robust diagnostic tool for accessible, rapid cardiac biomarker testing that meets the needs of diverse healthcare settings, from emergency care to underserved regions.

Self-Sustained Biophotocatalytic Nano-Organelle Reactors with Programmable DNA Switches for Combating Tumor Metastasis

Metastasis, the leading cause of mortality in cancer patients, presents challenges for conventional photodynamic therapy (PDT) due to its reliance on localized light and oxygen application to tumors. To overcome these limitations, a self-sustained organelle-mimicking nanoreactor is developed here with programmable DNA switches that enables bio-chem-photocatalytic cascade-driven starvation-photodynamic synergistic therapy against tumor metastasis. Emulating the compartmentalization and positional assembly strategies found in living cells, this nano-organelle reactor allows quantitative co-compartmentalization of multiple functional modules for the designed self-illuminating chemiexcited PDT system. Within the space-confined nanoreactor, biofuel glucose is converted to hydrogen peroxide (H2O2) which enhances luminol-based chemiluminescence (CL), consequently driving the generation of photochemical singlet oxygen (1O2) via chemiluminescence resonance energy transfer. Meanwhile, hemoglobin functions as a synchronized oxygen supplier for both glucose oxidation and PDT, while also exhibiting peroxidase-like activity to produce hydroxyl radicals (·OH). Crucially, the nanoreactor keeps switching off in normal tissues, with on-demand activation in tumors through toehold-mediated strand displacement. These findings demonstrate that this nanoreactor, which is self-sufficient in light and oxygen and precise in striking tumors, presents a promising paradigm for managing highly metastatic cancers.

An Activatable Chemiluminescent Self-Reporting Sulfur Dioxide Donor for Inflammatory Response and Regulation of Gaseous Vasodilation

Sulfur dioxide (SO2), being a novel gaseous signaling molecule, exhibits significant potential for application in the field of cardiovascular diseases. SO2 donors serve as crucial tools for the transportation and regulation of SO2 in vivo, facilitating the investigation of physiological roles associated with this molecule. However, the current therapeutic SO2 donors lack the capability to monitor the real-time release of SO2, thereby hindering accurate assessment of their therapeutic efficacy and target localization. Herein, we present an activatable chemiluminescent self-reporting SO2 donor (CL-SO2D) that can be selectively activated by peroxynitrite (ONOO-) to release SO2 and enable real-time visualization of the extent of release through chemiluminescent imaging. In vitro and cellular experiments demonstrate that CL-SO2D exhibits high selectivity and signal-to-noise ratio toward ONOO- and effectively facilitates the SO2 release process. Finally, CL-SO2D successfully achieved the response to the mouse inflammatory model and relieved vasoconstriction in zebrafish by releasing SO2 stimulated by ONOO-. The findings suggest that CL-SO2D exhibits impressive attributes in the diagnosis and treatment of SO2-related diseases, opening the gateway for developing low-background and high-sensitivity self-reporting SO2 donors.

Molecular probes for in vivo optical imaging of immune cells

Advancing the understanding of the various roles and components of the immune system requires sophisticated methods and technology for the detection of immune cells in their natural states. Recent advancements in the development of molecular probes for optical imaging have paved the way for non-invasive visualization and real-time monitoring of immune responses and functions. Here we discuss recent progress in the development of molecular probes for the selective imaging of specific immune cells. We emphasize the design principles of the probes and their comparative performance when using various optical modalities across disease contexts. We highlight molecular probes for imaging tumour-infiltrating immune cells, and their applications in drug screening and in the prediction of therapeutic outcomes of cancer immunotherapies. We also discuss the use of these probes in visualizing immune cells in atherosclerosis, lung inflammation, allograft rejection and other immune-related conditions, and the translational opportunities and challenges of using optical molecular probes for further understanding of the immune system and disease diagnosis and prognosis.

A silicon rhodamine 1,2-dioxetane chemiluminophore for in vivo near-infrared imaging

Near-infrared (NIR) chemiluminescent probes have attracted increasing attention in recent years due to their attractive properties for in vivo imaging. Herein, we developed a NIR chemiluminophore silicon rhodamine (SiRCL-1) based on the intramolecular energy transfer process from excited state benzoate to a silicon rhodamine emitter under aqueous conditions. SiRCL-1 exhibited dual emission peaks at 540 nm and 680 nm with a high signal penetration through tissue at 680 nm (>30 mm) and long-lasting in vivo luminescence (>50 min), demonstrating its significance as a chemiluminescence scaffold for biological application.

A steric hindrance-regulated probe with single excitation dual emissions for self-adaptive detection of biothiols and H2S in human urine samples and living cells

Sulfur-containing small molecules, mainly including cysteine (Cys), homocysteine (Hcy), glutathione (GSH), and hydrogen sulfide (H2S), are crucial biomarkers, and their levels in different body locations (living cells, tissues, blood, urine, saliva, etc.) are inconsistent and constantly changing. Therefore, it is highly meaningful and challenging to synchronously and accurately detect them in complex multi-component samples without mutual interference. In this work, we propose a steric hindrance-regulated probe, NBD-2FDCI, with single excitation dual emissions to achieve self-adaptive detection of four analytes. This probe was meticulously designed and constructed from a pKa-tuned 2FDCI fluorophore and a thiol-specific recognition moiety NBD. Except for 661 nm fluorescence for indicating the total biothiols and H2S, Cys and Hcy could trigger an additional 550 nm fluorescence. Utilizing the distinctive responses, the probe NBD-2FDCI exhibited exclusive linear ranges for GSH, Cys/Hcy, and H2S to avoid high-level component interference. Thus, the probe was then applied for sulfur compound measurements in urine samples, indicating metabolic disorder of Cys and H2S in bladder cancer patients. Moreover, adaptive imaging of probe NBD-2FDCI in cells was performed with the results being consistent with in vitro testing. In a word, spatial hindrance strategy-guided probes may exhibit broader prospects in the detection of similar components in complex samples.

Near-infrared AIE chemiluminescence probe for monitoring and evaluating singlet oxygen in vivo

The incorporation a "singlet oxygen (1O2) battery" into photodynamic therapy (PDT) could overcome the deficiency of tumor hypoxia in PDT and enhance its effect. However, real-time monitoring the 1O2 release efficiency of the 1O2 battery still presents a significant challenge in vivo. To address this issue, we have developed a bright aggregation-induced emission (AIE) chemiluminescence (CL) probe (DTLum), which conjugates a luminol unit with a donor-acceptor structured diketopyrrolopyrrole fluorophore, for the specific detection of 1O2. Subsequently, the DTLum nanoparticles (DTLum NPs) were prepared using PEO100-PPO65-PEO100 (Pluronic F127) as the surfactant. The DTLum NPs can detect 1O2 in aqueous solution with a bright near-infrared (NIR) CL signal (651 nm) and great tissue penetration (12.5 mm), making them suitable for the detection of 1O2 both in vitro (quantitative) and in vivo (qualitative). Notably, by utilizing the DTLum NPs, the process of 1O2 release in 1O2 batteries with different release rates can be visually monitored in cells and in vivo. This NIR CL probe provides a powerful platform for real-time monitoring and evaluating the release efficiency of 1O2 battery.

Intensive and Persistent Chemiluminescence from Orderly Arranged Ligands within Metal-Organic Frameworks for Inflammation Imaging

Chemiluminescence offers ultrasensitive imaging for the diagnosis of a variety of diseases by removing the interference from excitation light sources. Here, we prepared two chemiluminescent metal-organic frameworks (Mn-ADA and Zn-ADA) by using (2E,2'E)-3,3'-(anthracene-9,10-diyl)diacrylic acid (ADA) as a ligand. In Mn-ADA and Zn-ADA, the Mn atoms and Zn atoms are six-coordinated and eight-coordinated, respectively, and their frameworks are different in spatial structure. Due to the orderly arrangement of the fluorescence ligands and one-dimensional channel control of the diffusion of the reactant, Mn-ADA exhibits superstrong intensity and persistent chemiluminescence compared to ADA. The intensity of Mn-ADA is 43 times higher, and the lifetime is two times longer than that of ADA. Furthermore, different coordination also causes the chemiluminescence intensity of Mn-ADA to be stronger than that of Zn-ADA. It is established that Mn-ADA can detect H2O2 and image inflammation in mice without the excitation light. This methodology demonstrates the potential of metal-organic frameworks (MOFs) to enhance chemiluminescence and offers a new avenue for the development of MOF materials intended for biomedical application.

Unprecedented Photoinduced-Electron-Transfer Probe with a Turn-ON Chemiluminescence Mode-of-Action

PeT-based fluorescent probes were demonstrated to be powerful tools for detection and imaging, owing to their significant fluorescence enhancement in response to specific targets. While numerous examples of fluorescence-based PeT have been frequently reported, there is not even a single example of a PeT probe that operates via a chemiluminescence mode. Here we report the first PeT-based turn-on probe that acts via a chemiluminescent operation mode. We designed, synthesized, and evaluated a novel chemiluminescent probe, featuring a PeT-based turn-on mechanism. The probe consists of a phenoxy-1,2-dioxetane, linked to an azide unit that acts as a PeT quencher. Upon cycloaddition of a strained cycloalkyne with the azide, a triazole-dioxetane is formed, which undergoes relatively slow chemiexcitation, resulting in a measurement window with an exceptionally high signal-to-noise ratio (over 5000-fold). The PeT-dioxetane probe could effectively detect and image two model proteins labeled with strained cycloalkyne units (Myc-DBCO and Max-DBCO) through either NHS or maleimide conjugations. Comparative analysis shows that our PeT-based chemiluminescent probe significantly outperforms a commercially available fluorescent analog. We anticipate that the insights gained from this study will facilitate the development of additional chemiluminescent probes utilizing various PeT-quenching pathways.

Recent advances and design strategies for organic afterglow agents to enhance autofluorescence-free imaging performance

Long-lasting afterglow luminescence imaging that detects photons slowly being released from chemical defects has emerged, eliminating the need for real-time photoexcitation and enabling autofluorescence-free in vivo imaging with high signal-to-background ratios (SBRs). Organic afterglow nano-systems are notable for their tunability and design versatility. However, challenges such as unsatisfactory afterglow intensity, short emission wavelengths, limited activatable strategies, and shallow tissue penetration depth hinder their widespread biomedical applications and clinical translation. Such contradiction between promising prospects and insufficient properties has spurred researchers' efforts to improve afterglow performance. In this review, we briefly outline the general composition and mechanisms of organic afterglow luminescence, with a focus on design strategies and an in-depth understanding of the structure-property relationship to advance afterglow luminescence imaging. Furthermore, pending issues and future perspectives are discussed.

HClO-Activated Near-Infrared Chemiluminescent Probes with a Malononitrile Group for In-Vivo Imaging

Chemiluminescence (CL) imaging has emerged as a powerful approach to molecular imaging that allows exceptional sensitivity with virtually no background interference because of its unique capacity to emit photons without an external excitation source. Despite its high potential, the application of this nascent technique faces challenges because the current chemiluminescent agents have limited reactive sites, require complex synthesis, are insufficiently bright, and lack near-infrared emission. Herein, a series of HClO-activated chemiluminescent probes that exhibit robust near-infrared emission are studied. Specifically engineered to respond to HClO, a known biomarker of acute inflammation, these probes achieve high-contrast in vivo imaging by eliminating the need for constant external excitation. Comprehensive experimental and theoretical investigations demonstrate that the CL of the probes depends on the reactivity of the vinylene bonds, following a concerted decomposition of the oxidized chemiluminescent molecule. The application of these chemiluminescent nanoparticles in vivo facilitates high-contrast imaging of acute inflammation, providing real-time, high-contrast visualization of inflammatory conditions. This advancement signifies a leap forward for chemiluminescent nanoplatforms in biomedical imaging and expands the available methodologies in this field.

Triplet Electron Exchange in Carbon Nanodots-assisted Long-persistent near-infrared Chemiluminescence for Oncology Synergistic Imaging and Therapy

In classical photodynamic therapy, tumor cells are killed by the cytotoxic species via type-I/II photochemical reactions, seriously limited by the external photoexcitation and hypoxia. Herein, the electron transfer mechanism between fluorophores and peroxalate-H2O2 reaction is investigated and the singlet/triplet electron exchange is utilized to achieve long-persistent chemiluminescence imaging and synergistic type-I/II/III photodynamic therapy. As a proof-of-concept, the photosensitizers of carbon nanodots (CDs)-loaded chlorin e6 (CDs-Ce6) are designed and integrated with the peroxalate molecules, and the as-prepare polymer carbon nanodots (p-CDs) exhibit novel tumor microenvironment (TME)-responsive long-persistent near-infrared CL and photochemical reactions, evoking the in vivo imaging and synergistic dynamic therapy in tumor tissue. Mechanistically, the excess reactive oxygen species in TME can trigger the chemically initiated singlet/triplet electron exchange between the hydrophobic CDs-Ce6 and peroxalate-derived 1,2-dioxetanes and thus the excess excited singlet/triplet electron of the CDs-Ce6 can ensure the long-persistent near-infrared CL, type I/II photochemical production of hydroxyl radicals, superoxide radical and singlet oxygen, and type III photochemical damage of maladjusted biomacromolecules, enabling the long-persistent near-infrared biological imaging and enhanced cancer therapy. These results shed a new sight into the energy transfer mechanism in chemiluminescence and pave a new sight into the architecture of multifunctional theragnostic nanoplatforms.

Multi-level structured nanoparticles prepared by microfluidics control method for efficient and sensitive chemiluminescence immunoassay

The properties of nanomaterials are heavily influenced by their size effects. Utilizing the self-assembly principle offers a promising avenue for crafting innovative nanomaterials, yet controlling this process at the microscopic level presents significant challenges, hindering effective regulation of nanomaterial morphology. Microfluidic technology, however, offers precise control over fluid velocities within microchannels, enabling micro-level manipulation. In this study, we synthesized amphiphilic molecules HP (Hematin@NH2-PEG-COOH) through hematin modification, leveraging microfluidic techniques to encapsulate luminol within HP molecules, resulting in the formation of highly efficient chemiluminescence (CL) HPL (HP@Luminol) nanoparticles. The size effects and intricate multi-level structures achieved during encapsulation endowed these nanoparticles with enhanced catalytic capabilities for CL. Finally, we used HPL nanoparticles as luminescent markers to develop a CL immunosensor for the sensitive detection of the tumor marker carcinoembryonic antigen (CEA), achieving satisfactory results. This innovative approach not only expands the repertoire of nanomaterial design and synthesis but also offers a practical solution for sensitive biomarker detection. Overall, this research introduces a novel strategy for designing and fabricating advanced nanomaterials, underscoring the potential of microfluidic technology in nanoscience and biosensing applications.

Recent Advances in Strategies to Enhance Photodynamic and Photothermal Therapy Performance of Single-Component Organic Phototherapeutic Agents

Photodynamic therapy (PDT) and photothermal therapy (PTT) have emerged as promising treatment options, showcasing immense potential in addressing both oncologic and nononcologic diseases. Single-component organic phototherapeutic agents (SCOPAs) offer advantages compared to inorganic or multicomponent nanomedicine, including better biosafety, lower toxicity, simpler synthesis, and enhanced reproducibility. Nonetheless, how to further improve the therapeutic effectiveness of SCOPAs remains a challenging research area. This review delves deeply into strategies to improve the performance of PDT or PTT by optimizing the structural design of SCOPAs. These strategies encompass augmenting reactive oxygen species (ROS) generation, mitigating oxygen dependence, elevating light absorption capacity, broadening the absorption region, and enhancing the photothermal conversion efficiency (PCE). Additionally, this review also underscores the ideal strategies for developing SCOPAs with balanced PDT and PTT. Furthermore, the potential synergies are highlighted between PDT and PTT with other treatment modalities such as ferroptosis, gas therapy, chemotherapy, and immunotherapy. By providing a comprehensive analysis of these strategies, this review aspires to serve as a valuable resource for clinicians and researchers, facilitating the wider application and advancement of SCOPAs-mediated PDT and PTT.

Rapid, Non-Invasive, Accurate Diagnosis and Efficient Clearance of Metastatic Lymph Nodes

Sentinel lymph node (SLN) biopsy is currently the standard procedure for clinical cancer diagnosis and treatment, but still faces the risks of false negatives and tumor metastasis, as well as time-consuming pathological evaluation procedure. Herein, we proposed a near-infrared-II (NIR-II, 1000-1700 nm) theranostic nanosystem (FLAGC) for rapid, non-invasive, accurate diagnosis and efficient clearance of metastatic lymph nodes in breast cancer. Initialized by chlorin e6 (Ce6), a pH-sensitive amphiphilic amino acid fluorenylmethoxycarbonyl-L-histidine (Fmoc-His) was assembled with Gd3+, luminol, and AgAuSe quantum dots (AAS QDs) to form FLAGC. In FLAGC, luminol and AAS QDs form a NIR-II chemical resonance energy transfer (CRET) system (Luminol-AAS); Ce6 initiates the assembly and also serves as a photosensitizer. Upon subcutaneous injection, FLAGC is easily drained into SLNs, achieving their precise localization. Subsequently, the acidity of tumor microenvironment triggers the rapid disassembly of FLAGC, exposing Luminol-AAS. myeloperoxidase (MPO) secreted by tumor-associated macrophages and neutrophils in SLNs mediates the oxidation of luminol, lighting up AAS QDs through the CRET process for precise diagnosis of metastatic lymph nodes. Moreover, highly efficient clearance of positive lymph nodes is achieved through Ce6-mediated photodynamic therapy. Our strategy provides a new paradigm for identifying and eliminating clinically metastatic lymph nodes.

Fluorescent Particles Based on Aggregation-Induced Emission for Optical Diagnostics of the Central Nervous System

In 2001, Tang's team discovered a unique type of luminogens with substantial enhanced fluorescence upon aggregation and introduced the concept of "aggregation-induced emission (AIE)". Unlike conventional fluorescent materials, AIE luminogens (AIEgens) emit weak or no fluorescence in solution but become highly fluorescent in aggregated or solid states, due to a mechanism known as restriction of intramolecular motions (RIM). Initially considered a purely inorganic chemical phenomenon, AIE was later applied in biomedicine to improve the sensitivity of immunoassays. Subsequently, AIE has been extensively explored in various biomedical applications, especially in cell imaging. Early studies achieved nonspecific cell imaging using nontargeted AIEgens, and later, specific cellular imaging was realized through the design of targeted AIEgens. These advancements have enabled the visualization of various biomacromolecules and intracellular organelles, providing valuable insights into cellular microenvironments and statuses. Neurological disorders affect over 3 billion people worldwide, highlighting the urgent need for advanced diagnostic and therapeutic tools. AIEgens offer promising opportunities for imaging the central nervous system (CNS), including nerve cells, neural tissues, and blood vessels. This review focuses on the application of AIEgens in CNS imaging, exploring their roles in the diagnosis of various neurological diseases. We will discuss the evolution and conclude with an outlook on the future challenges and opportunities for AIEgens in clinical diagnostics and therapeutics of CNS disorders.

Molecular Engineering of Direct Activated NIR-II Chemiluminescence Platform for In Vivo Chemiluminescence-fluorescence Duplex Imaging

Chemiluminescence (CL) is a self-illuminating phenomenon fueled by chemical energy instead of extra excited light, which features superiority in sensitivity, signal-to-background ratios, and imaging depth. Strategies to synthesize a CL emission unimolecular skeleton in the second near-infrared window (NIR-II) and a unimolecular probe with direct duplex NIR-II [CL/fluorescence (FL)] emission are lacking. Here, we employ modular synthesis routes to construct a series of directly activated NIR-II CL emission unimolecular probes with a maximum emission wavelength of up to 1060 nm, and use them for real-time and continuous detection of the superoxide anion generated in acetaminophen induced liver injury in a female mice model under both NIR-II CL and NIR-II FL imaging channels. Thus, this study establishes a directly activatable NIR-II CL emission unimolecular skeleton, validating the scalability of this duplex NIR-II CL/FL imaging platform in bioactive molecule detection and disease diagnosis.

Universal sulfatase-based chemiluminescence biosensing platform: Validation via AFP detection in clinical blood samples

Enzyme-catalyzed chemiluminescence has been widely used in the field of biomedicine, especially in the test kit for various biomarkers. However, the currently reported enzyme-catalyzed chemiluminescence systems suffered from the addition of oxidizing substances, short emission wavelength, and susceptibility to interference by autofluorescence. In this paper, a universal sulfatase-based chemiluminescence system with NIR was developed, in which the designed substrate QM-CF could be transformed into 1,2-dioxetane derivate in the presence of sulfatase and oxygen. This system exhibited long emission wavelengths and CL half-time, a high signal-noise ratio, and without other additives. Importantly, the sulfatase-based chemiluminescence enzyme-linked immunoassay platform was successfully constructed and could be generally applied to detect biomarkers. As a proof of concept, the sulfatase-labeled AFP antibody and substate QM-CF were conveniently suitable for commercial AFP test kits, leading to satisfactory detection results of AFP in clinical blood samples.

Brightness Strategies toward NIR-II Emissive Conjugated Materials: Molecular Design, Application, and Future Prospects

Recent advances have been made in second near-infrared (NIR-II) fluorescence bioimaging and many related applications because of its advantages of deep penetration, high resolution, minimal invasiveness, and good dynamic visualization. To achieve high-performance NIR-II fluorescence bioimaging, various materials and probes with bright NIR-II emission have been extensively explored in the past few years. Among these NIR-II emissive materials, conjugated polymers and conjugated small molecules have attracted wide interest due to their native biosafety and tunable optical performance. This review summarizes the brightness strategies available for NIR-II emissive conjugated materials and highlights the recent developments in NIR-II fluorescence bioimaging. A concise, detailed overview of the molecular design and regulatory approaches is provided in terms of their high brightness, long wavelengths, and superior imaging performance. Then, various typical cases in which bright conjugated materials are used as NIR-II probes are introduced by providing step-by-step examples. Finally, the current problems and challenges associated with accessing NIR-II emissive conjugated materials for bright NIR-II fluorescence bioimaging are briefly discussed, and the significance and future prospects of these materials are proposed to offer helpful guidance for the development of NIR-II emissive materials.

A Review of Current Developments in Functionalized Mesoporous Silica Nanoparticles: From Synthesis to Biosensing Applications

Functionalized mesoporous silica nanoparticles (MSNs) have been widely investigated in the fields of nanotechnology and material science, owing to their high surface area, diverse structure, controllable cavity, high biocompatibility, and ease of surface modification. In the past few years, great efforts have been devoted to preparing functionalized MSNs for biosensing applications with satisfactory performance. The functional structure and composition in the synthesis of MSNs play important roles in high biosensing performance. With the development of material science, diverse functional units have been rationally incorporated into mesoporous structures, which endow MSNs with design flexibility and multifunctionality. Here, an overview of the recent developments of MSNs as nanocarriers is provided, including the methodologies for the preparation of MSNs and the nanostructures and physicochemical properties of MSNs, as well as the latest trends of MSNs and their use in biosensing. Finally, the prospects and challenges of MSNs are presented.

Dual-Locked Chemiluminescent Probe Enables Precise Imaging and Timely Diagnosis of Colitis via Chymotrypsin/Vanin-1 Cascade Activation

The development of precise diagnosis and the discovery of individualized drugs go together to provide effective therapy against inflammatory bowel disease (IBD). The exploitation of the unique imaging advantages of chemiluminescent probes represents a pivotal strategy for achieving this goal. Nevertheless, the dual-locked strategy, which is believed to enhance precision, is rarely employed in the design of chemiluminescent probes. A novel dual-locked chemiluminescent probe, BPan-CL, was designed based on IBD candidate biomarkers chymotrypsin (CHT) and vanin-1. BPan-CL exhibited specific reactivity and chemiluminescence response when subjected to simultaneous stimulation of CHT and vanin-1, with a signal-to-noise ratio superior to that of the fluorescent probe with the same dual-locked mode. In both live cell and IBD mice imaging, BPan-CL demonstrated superior sensitivity compared to its single-locked counterpart, Pan-CL. In contrast to Pan-CL, BPan-CL was able to more accurately identify IBD and healthy mice by in vivo imaging and allowed for early prediction of IBD using a noninvasive fecal test. BPan-CL has identified CHT and vanin-1 as valuable combinatorial biomarkers for accurate and early IBD diagnosis. This strategy has significant potential for use in biomedical imaging and future individualized therapies.

Nanomaterial-based regulation of redox metabolism for enhancing cancer therapy

Altered redox metabolism is one of the hallmarks of tumor cells, which not only contributes to tumor proliferation, metastasis, and immune evasion, but also has great relevance to therapeutic resistance. Therefore, regulation of redox metabolism of tumor cells has been proposed as an attractive therapeutic strategy to inhibit tumor growth and reverse therapeutic resistance. In this respect, nanomedicines have exhibited significant therapeutic advantages as intensively reported in recent studies. In this review, we would like to summarize the latest advances in nanomaterial-assisted strategies for redox metabolic regulation therapy, with a focus on the regulation of redox metabolism-related metabolite levels, enzyme activity, and signaling pathways. In the end, future expectations and challenges of such emerging strategies have been discussed, hoping to enlighten and promote their further development for meeting the various demands of advanced cancer therapies. It is highly expected that these therapeutic strategies based on redox metabolism regulation will play a more important role in the field of nanomedicine.

A Bicyclic Dioxetane Chemiluminescence Nanoprobe for Peroxynitrite Imaging in Vivo

Peroxynitrite (ONOO-) is a critical biomarker associated with a wide array of diseases including cancer, inflammatory conditions, and neurodegenerative disorders. This study introduces an innovative chemiluminescence nanoprobe (CLNP) based on a bicyclic dioxetane structure, designed for highly sensitive and specific in vivo imaging of ONOO-. Our CLNP demonstrates exceptional capabilities in generating high-contrast imaging of disease lesions, with applications verified across tumor models, acute inflammation, and acute liver injury scenarios. Key findings highlight the probe's rapid response to oxidative species, superior tissue penetration, and high signal-to-noise ratio, underscoring its potential for real-time diagnostic applications. This work represents an important advance in the field of diagnostic imaging using CL probes, offering promising avenues for the early detection and treatment of ONOO--related pathologies.

DNA Conformation-Regulated Hemin Switch for Lab-on-Chip Chemiluminescent Detection of an Antibody Secreted from Hybridoma Cells

This work designed a DNA conformation-regulated hemin switch for rapid chemiluminescent (CL) detection of a monoclonal antibodies. This switch was performed with an affinity probe and an inhibition probe, which were conveniently prepared by hybridizing hemin-labeled DNA1 with KHL peptide-labeled DNA2 and binding biotin-labeled DNA3 to streptavidin, respectively. In the absence of the target antibody, streptavidin-DNA3 could hybridize with hemin-DNA1/KHL-DNA2 to release KHL-DNA2, which led to the loss of hemin activity due to the affinity hindrance of streptavidin-DNA3. After the KHL peptide was recognized by the target antibody, the strand replacement hybridization could be inhibited by the bound antibody, which retained the high catalytic activity of hemin overhung on the antibody-bound affinity probe for a CL reaction, leading to a "signal-on" process for CL antibody detection. Using a KHL-specific antibody, anti-proprotein convertase subtilisin/kexin type 9 antibody (PCSK9-Ab), as a target model and common L012-1,2,4-triazole-H2O2 CL system, the designed switch showed a detection range of 10 ng mL-1 to 1 μg mL-1 with a detection limit of 4.16 ng mL-1 (56.2 pM) and a short analytical time of 6.5 min. The proposed quick method could simply be used for lab-on-chip CL detection of PCSK9-Ab in situ-secreted from PCSK9-6E3 hybridoma cells, which showed an accuracy of 90.2% compared with the statistical results from general fluorescence imaging, providing a potential technique for screening specific hybridoma cells.

Light/X-ray/ultrasound activated delayed photon emission of organic molecular probes for optical imaging: mechanisms, design strategies, and biomedical applications

Conventional optical imaging, particularly fluorescence imaging, often encounters significant background noise due to tissue autofluorescence under real-time light excitation. To address this issue, a novel optical imaging strategy that captures optical signals after light excitation has been developed. This approach relies on molecular probes designed to store photoenergy and release it gradually as photons, resulting in delayed photon emission that minimizes background noise during signal acquisition. These molecular probes undergo various photophysical processes to facilitate delayed photon emission, including (1) charge separation and recombination, (2) generation, stabilization, and conversion of the triplet excitons, and (3) generation and decomposition of chemical traps. Another challenge in optical imaging is the limited tissue penetration depth of light, which severely restricts the efficiency of energy delivery, leading to a reduced penetration depth for delayed photon emission. In contrast, X-ray and ultrasound serve as deep-tissue energy sources that facilitate the conversion of high-energy photons or mechanical waves into the potential energy of excitons or the chemical energy of intermediates. This review highlights recent advancements in organic molecular probes designed for delayed photon emission using various energy sources. We discuss distinct mechanisms, and molecular design strategies, and offer insights into the future development of organic molecular probes for enhanced delayed photon emission.

Reactive oxygen species-mediated organic long-persistent luminophores light up biomedicine: from two-component separated nano-systems to integrated uni-luminophores

Organic luminophores have been widely utilized in cells and in vivo fluorescence imaging but face extreme challenges, including a low signal-to-noise ratio (SNR) and even false signals, due to non-negligible background signals derived from real-time excitation lasers. To overcome these challenges, in the last decade, functionalized organic long-persistent luminophores have gained much attention. Such luminophores could not only overcome the biological toxicity of inorganic long-persistent luminescent materials (metabolic toxicity and leakage risk of inorganic heavy metals), but also continue to emit long-persistent luminescence after removing the excitation source, thus effectively improving imaging quality. More importantly, organic long-persistent luminophores have good structure tailorability for the construction of activable probes, which is favorable for biosensing. Recently, the development of reactive oxygen species (ROS)-mediated long-persistent (ROSLP) luminophores (especially organic small-molecule ROSLP luminophores) is still in the rising stage. Notably, ROSLP luminophores for in vivo imaging have experienced from two-component separated nano-systems to integrated uni-luminophores, which obtained gradually better designability and biocompatibility. In this review, we summarize the progress and challenges of organic long-persistent luminophores, focusing on their development history, long-persistent luminescence working mechanisms, and biomedical applications. We hope that these insights will help scientists further develop functionalized organic long-persistent luminophores for the biomedical field.

Chemiexcitation Acceleration of 1,2-Dioxetanes by Spiro-Fused Six-Member Rings with Electron-Withdrawing Motifs

The chemiluminescent light-emission pathway of phenoxy-1,2-dioxetane luminophores attracts growing interest within the scientific community. Dioxetane probes undergoing rapid flash-type chemiexcitation exhibit higher detection sensitivity than those with a slow glow-type chemiexcitation rate. We discovered that dioxetanes fused to non-strained six-member rings, with hetero atoms or inductive electron-withdrawing groups, present both accelerated chemiexcitation rates and elevated chemical stability compared to dioxetanes fused to four-member strained rings. DFT computational simulations supported the chemiexcitation acceleration observed by spiro-fused six-member rings with inductive electron-withdrawing groups of dioxetanes. Specifically, a spiro-dioxetane with a six-member sulfone ring exhibited a chemiexcitation rate 293-fold faster than that of spiro-adamantyl-dioxetane. A turn-ON dioxetane probe for the detection of the enzyme β-galactosidase, containing the six-member sulfone unit, exhibited a S/N value of 108 in LB cell growth medium. This probe demonstrated a substantial increase in detection sensitivity towards E. coli bacterial cells expressing β-galactosidase, with an LOD value that is 44-fold more sensitive than that obtained by the adamantyl counterpart. The accelerated chemiexcitation and the elevated chemical stability presented by dioxetane containing a spiro-fused six-member ring with a sulfone inductive electron-withdrawing group, make it an ideal candidate for designing efficient turn-on chemiluminescent probes with exceptionally high detection sensitivity.

Metal-Phenolic Networks: A Promising Frontier in Cancer Theranostics

The burgeoning field of cancer theranostics has been significantly advanced by the development of Metal-Phenolic Networks (MPNs), a new class of supramolecular architectures that integrate the advantages of metals and polyphenols. This review focuses on MPNs and their promising applications in cancer theranostics. Through a systematic literature search spanning from 2010 to 2023 in databases including PubMed, Scopus, and Web of Science. The period of search was justified by the rapid evolution of nanomaterials in cancer therapy, with MPNs emerging as a significant player in biomedical applications within the specified timeframe. This review discusses the classification and structure of polyphenolic compounds, as well as their mechanisms of action in cancer treatment. The applications of MPNs in chemotherapy drug delivery, photothermal therapy, chemodynamic therapy, biomedical imaging, and synergistic therapy are especially detailed. The authors emphasize the significance of MPNs in cancer nanomedicine and look forward to their future development directions.

Glow-type luminol chemiluminescence based on a supramolecular enhancer of cyclodextrin

BACKGROUND

Chemiluminescence (CL) bioassay is one of the most advanced and used detection method in clinical diagnosis and biomedical research because of the advantages of low background, easy operation, and wide-field imaging without a light source or microscope. The luminol/hydrogen peroxide/horseradish peroxidase (luminol/H2O2/HRP) system is the most popular CL system, but its application in high-throughput imaging detection is challenged due to its low luminescence efficiency and flash-type emission which is difficult in ensuring the reproducibility and consistency of detection results.

RESULTS

We reported a glow-type CL system of luminol@CD/H2O2/HRP by using a supramolecular enhancer of cyclodextrin (CD). This luminol@CD/H2O2/HRP system exhibited a luminescence lifetime of 41 min for sensitive and accurate imaging analysis. The long-lasting CL emission was attributed to the formation of a 1:1 host-guest complex between luminol and CD, which could stabilize the emitter and effectively reduce nonradiative relaxation. The formation of luminol@CD complex was determined through NMR experiments and theoretical analysis. Under optimum conditions, the luminol@CD/H2O2/HRP system showed higher sensitivity and much better precision than classical luminol/H2O2/HRP system for imaging detection of HRP. Especially, this glow-type luminol@CD/H2O2/HRP system realized CL imaging of microwell arrays on microfluidic chips. In addition, the luminol@CD/H2O2/HRP system was successfully applied for point-of-care detection of 17β-estradiol based on a competitive mechanism of host-guest recognition.

SIGNIFICANCE

An efficient CL system is crucial for obtaining reproducible and consistent results for accurate detection. Our luminol@CD/H2O2/HRP system emitted strong and persistent luminescence, resulting in reliability and efficiency at both CL macroscopic and microscopic imaging detection. We expected the luminol@CD/H2O2/HRP CL system to be applied in various detection fields.

Leveraging the Photofunctions of Transition Metal Complexes for the Design of Innovative Phototherapeutics

Despite the advent of various medical interventions for cancer treatment, the disease continues to pose a formidable global health challenge, necessitating the development of new therapeutic approaches for more effective treatment outcomes. Photodynamic therapy (PDT), which utilizes light to activate a photosensitizer to produce cytotoxic reactive oxygen species (ROS) for eradicating cancer cells, has emerged as a promising approach for cancer treatment due to its high spatiotemporal precision and minimal invasiveness. However, the widespread clinical use of PDT faces several challenges, including the inefficient production of ROS in the hypoxic tumor microenvironment, the limited penetration depth of light in biological tissues, and the inadequate accumulation of photosensitizers at the tumor site. Over the past decade, there has been increasing interest in the utilization of photofunctional transition metal complexes as photosensitizers for PDT applications due to their intriguing photophysical and photochemical properties. This review provides an overview of the current design strategies used in the development of transition metal complexes as innovative phototherapeutics, aiming to address the limitations associated with PDT and achieve more effective treatment outcomes. The current challenges and future perspectives on the clinical translation of transition metal complexes are also discussed.

Advances and perspectives in use of semisolid formulations for photodynamic methods

Although nearly 30 years have passed since the introduction of the first clinically approved photosensitizer for photodynamic therapy, progress in developing new pharmaceutical formulations remains unsatisfactory. This review highlights that despite years of research, many recurring challenges and issues remain unresolved. The paper includes an analysis of selected essential studies involving aminolevulinic acid and its derivatives, as well as other photosensitizers with potential for development as medical products. Among various possible vehicles, special attention is given to gelatin, alginates, poly(ethylene oxide), polyacrylic acid, and chitosan. The focus is particularly on infectious and cancerous diseases. Key aspects of developing new semi-solid drug forms should prioritize the creation of easily manufacturable and biocompatible preparations for clinical use. At the same time, new formulations should preserve the primary function of photosensitizers, which is the generation of reactive oxygen species capable of destroying pathogenic cells or tumors. Additionally, the use of adjuvant properties of carriers, which can enhance the effectiveness of macrocycles, is emphasized, especially in chitosan-based antibacterial formulations. Current research indicates that many promising dyes and macrocyclic compounds with high potential as photosensitizers in photodynamic therapy remain unexplored in formulation and development work. This review outlines potential new and previously explored pathways for advancing photosensitizers as active pharmaceutical ingredients (APIs).

Activatable Fluorescence and Bio/Chemiluminescence Probes for Aminopeptidases: From Design to Biomedical Applications

Aminopeptidases are exopeptidases that catalyze the cleavage of amino acid residues from the N-terminal fragment of protein or peptide substrates. Owing to their function, they play important roles in protein maturation, signal transduction, cell-cycle control, and various disease mechanisms, notably in cancer pathology. To gain better insights into their function, molecular imaging assisted by fluorescence and bio/chemiluminescence probes has become an indispensable method to their superiorities, including excellent sensitivity, selectivity, and real-time and noninvasive imaging. Numerous efforts are made to develop activatable probes that can effectively enhance efficiency and accuracy as well as minimize the side effects. This review is classified according to the type of aminopeptidases, summarizing some recent works on the design, work mechanism, and sensing, imaging, and theranostic performance of their activatable probe. Finally, the current challenges are outlined in developing activatable probes for aminopeptidases and provide possible solutions for future advancements.

Recent Advances in the Synthesis and Optical Applications of Acridine-based Hybrid Fluorescent Dyes

Acridine-based hybrid fluorescent dyes represent a category of dyes that integrate the acridine chromophore with other functional groups or materials to enhance their fluorescence properties. These dyes have garnered substantial attention across various domains, encompassing bioimaging, sensing, and optoelectronics. In recent years, researchers have directed their efforts toward fabricating acridine-based hybrid fluorescent dyes with improved water solubility, biocompatibility, and targeting capabilities. These advancements have facilitated their utilization in biological imaging applications, such as monitoring cellular processes, investigating protein-protein interactions, and detecting specific biomolecules. This review delineates the recent progress in synthesizing acridine-based hybrid fluorescent dyes and their applications in optical properties over the past decade. This review is anticipated to catalyze the development of innovative fluorescent materials featuring heightened properties and functionalities.

Self-Illuminating Copper-Luminol Coordination Polymers for Bioluminescence Imaging of Oxidative Damage

Timely detection of reactive oxygen species (ROS) accumulated during inflammation is essential for an early disease diagnosis. Compared to fluorescence probes with limited sensitivity and accuracy, chemiluminescence (CL) imaging offers the potential for highly sensitive molecular visualization of ROS by minimizing background interferences. However, the development of bright and easily manufacturable CL probes for ROS imaging remains challenging. In this study, a novel chemiluminescent nanoprobe named Cu-Lum@NPs for ROS imaging in inflammation was synthesized by using a one-step solvothermal method. The Cu-Lum@NPs, which are composed of coordination polymers containing copper ions and luminol (Lum), demonstrate intrinsic peroxidase-like activity that relies on Cu(I) as the catalytic active center to initiate the Fenton reaction. This catalytic process facilitates the decomposition of hydrogen peroxide (H2O2) into hydroxyl radicals (•OH) and superoxide anion radicals (O2•-), leading to the oxidation of Lum and inducing strong luminescence. Cu-Lum@NPs, displaying nanozyme characteristics, were observed to accelerate and enhance the ROS-responsive luminescence (10-1600-fold in solution and over 100-fold in neutrophils) and notably extend persistent luminescence. The Cu-Lum@NPs allowed for CL imaging of endogenous ROS in living cells and animals with an outstanding signal-to-noise ratio exceeding 96 and facilitated oxidative damage luminescence imaging for tissue-specific detection. The study presents Cu-Lum@NPs, a highly sensitive and easily manufacturable chemiluminescent nanoprobe for ROS imaging both in vitro and in vivo, exhibiting enhanced luminescence and prolonged persistence for ROS-related disease detection.

Development of chemiluminescent systems and devices for analytical applications

Chemiluminescence (CL) refers to the light-emitting phenomenon resulting from chemical reactions. Due to its simplicity in terms of instrumentation and high sensitivity, CL plays a critical role in analytical chemistry and has developed rapidly in recent years. In this review, we discuss the efforts made by our group in the field of CL. This includes exploring new luminophores that function under neutral pH conditions, developing oxidant- and reactive oxygen species-based coreactants (e.g. artemisinin and thiourea dioxide) for luminol and lucigenin CL, utilizing nanomaterial-based CL signal amplification and employing innovative ultrasound devices for CL and their analytical applications. We discussed the CL amplification mechanisms of these systems in detail. Finally, we summarize the challenges and prospects for the future development of CL.

Research and applications of nanoclays: A review

Nanoclays, a specific type of nanomaterial, have emerged as versatile and dynamic materials, with tremendous potential for advanced functional applications. Despite publishing a large number of research articles, there are relatively few review articles on this topic. This comprehensive review delves into the most widely used nanoclays and explores the diverse range of applications in different fields, such as aerospace, automobile, construction, biomedical, food packaging, and polymer composites. With their ability to enhance the performance of materials and products, nanoclays have become a highly desired material in various industries. The challenges associated with nanoclays like complex properties, difficulty in developing new synthesis methods, and challenges in investigating long‐term durability and stability have been summarized. The future research directions with the exciting possibilities to develop future innovative materials have been highlighted at the end of the article.

Highlights

Boosting Chemiexcitation of Phenoxy-1,2-dioxetanes through 7-Norbornyl and Homocubanyl Spirofusion

The chemiluminescent light-emission pathway of phenoxy-1,2-dioxetane luminophores is increasingly attracting the scientific community's attention. Dioxetane probes that undergo rapid, flash-type chemiexcitation demonstrate higher detection sensitivity than those with a slower, glow-type chemiexcitation rate. This is primarily because the rapid flash-type produces a greater number of photons within a given time. Herein, we discovered that dioxetanes fused to 7-norbornyl and homocubanyl units present accelerated chemiexcitation rates supported by DFT computational simulations. Specifically, the 7-norbornyl and homocubanyl spirofused dioxetanes exhibited a chemiexcitation rate 14.2-fold and 230-fold faster than that of spiro-adamantyl dioxetane, respectively. A turn-ON dioxetane probe for the detection of the enzyme β-galactosidase, containing the 7-norbornyl spirofused unit, exhibited an S/N value of 415 at a low enzyme concentration. This probe demonstrated an increase in detection sensitivity toward β-galactosidase expressing bacteria E. coli with a limit-of-detection value that is 12.8-fold more sensitive than that obtained by the adamantyl counterpart. Interestingly, the computed activation free energies of the homocubanyl and 7-norbornyl units were correlated with their CCsC spiro-angle to corroborate the measured chemiexcitation rates.

Development of a Modular miRNA-Responsive Biosensor for Organ-Specific Evaluation of Liver Injury

MicroRNAs (miRNAs) are increasingly being considered essential diagnostic biomarkers and therapeutic targets for multiple diseases. In recent years, researchers have emphasized the need to develop probes that can harness extracellular miRNAs as input signals for disease diagnostics. In this study, we introduce a novel miRNA-responsive biosensor (miR-RBS) designed to achieve highly sensitive and specific detection of miRNAs, with a particular focus on targeted organ-specific visualization. The miR-RBS employs a Y-structured triple-stranded DNA probe (Y-TSDP) that exhibits a fluorescence-quenched state under normal physiological conditions. The probe switches to an activated state with fluorescence signals in the presence of high miRNA concentrations, enabling rapid and accurate disease reporting. Moreover, the miR-RBS probe had a modular design, with a fluorescence-labeled strand equipped with a functional module that facilitates specific binding to organs that express high levels of the target receptors. This allowed the customization of miRNA detection and cell targeting using aptameric anchors. In a drug-induced liver injury model, the results demonstrate that the miR-RBS probe effectively visualized miR-122 levels, suggesting it has good potential for disease diagnosis and organ-specific imaging. Together, this innovative biosensor provides a versatile tool for the early detection and monitoring of diseases through miRNA-based biomarkers.

Signal-On Detection of Dopamine and Tyrosinase Using Tris(hydroxypropyl)phosphine as a New Lucigenin Chemiluminescence Coreactant

Dopamine (DA) is a very imperative neurotransmitter in our body, since it contributes to several physiological processes in our body, for example, memory, feeling, cognition, cardiovascular diseases, and hormone secretion. Meanwhile, tyrosinase is a critical biomarker for several dangerous skin diseases, including vitiligo and melanoma cancer. Most of the reported chemiluminescent (CL) methods for monitoring DA and tyrosinase are signal-off biosensors. Herein, we introduce a new chemiluminescent "signal-on" system, lucigenin-tris(hydroxypropyl)phosphine (THPP), for the selective determination of DA and tyrosinase. THPP is well known as a versatile and highly water-soluble sulfhydryl-reducing compound that is more highly stable against air oxidation than common disulfide reductants. By employing THPP for the first time as an efficient lucigenin coreactant, the lucigenin-THPP system has shown a high CL response (approximately 16-fold) compared to the lucigenin-H2O2 classical CL system. Surprisingly, DA can remarkably boost the CL intensity of the lucigenin-THPP CL system. Additionally, tyrosinase can efficiently catalyze the conversion of tyramine to DA. Therefore, lucigenin-THPP was employed as an ultrasensitive and selective signal-on CL system for the quantification of DA, tyrosinase, and THPP. The linear ranges for the quantification of DA, tyrosinase, and THPP were 50-1000 nM, 0.2-50 μg/mL, and 0.1-800 μM, respectively. LODs for DA and tyrosinase were estimated to be 24 nM and 0.18 μg/mL, respectively. Additionally, the CL system has been successfully employed for the detection of tyrosinase in human serum samples and the assay of DA in human serum samples as well as in dopamine injection ampules with excellent obtained recoveries.