NIR-II AIEgens for Infectious Diseases Phototheranostics.

Pathogenic infectious diseases have persistently posed significant threats to public health. Phototheranostics, which combines the functions of diagnostic imaging and therapy, presents an extremely promising solution to block the spread of pathogens as well as the outbreak of epidemics owing to its merits of a wide-spectrum of activity, high controllability, non-invasiveness, and difficult to acquire resistance. Among multifarious phototheranostic agents, second near-infrared (NIR-II, 1000-1700 nm) aggregation-induced emission luminogens (AIEgens) are notable by virtue of their deep penetration depth, excellent biocompatibility, balanced radiative and nonradiative decay and aggregation-enhanced theranostic performance, making them an ideal option for combating pathogens. This minireview provides a systematical summary of the latest advancements in NIR-II AIEgens with emphasis on the molecular design and nanoplatform formulation to fulfill high-efficiency in treating bacterial and viral pathogens, classified by disease models. Then, the current challenges, potential opportunities, and future research directions are presented to facilitate the further progress of this emerging field.

NIR-II-Responsive Hybrid System Achieves Cascade-Augmented Antitumor Immunity via Genetic Engineering of Both Bacteria and Tumor Cells.

The combination of nanoparticles and tumor-targeting bacteria for cancer immunotherapy can overcome the shortcomings of poor nanoparticle accumulation, limited penetration, and restricted distribution. However, it remains a great challenge for the hybrid system to improve therapeutic efficacy through the simultaneous and controllable regulation of immune cells and tumor cells. Herein, a hybrid therapeutic platform is rationally designed to achieve immune cascade-augmented cancer immunotherapy. To construct the hybrids, photothermal nanoparticles responsive to light in the second near-infrared (NIR-II) region are conjugated onto the surface of engineered bacteria through pH-responsive Schiff base bonds. Taking advantage of the hypoxia targeting and deep penetration characteristics of the bacteria, the hybrids can accumulate at tumor sites. Then nanoparticles detach from the bacteria to realize genetic engineering of tumor cells, which induces tumor cell apoptosis and down-regulate the expression of programmed cell death ligand 1 to alleviate immunosuppressive tumor microenvironment. The mild photothermal heating can not only induce tumor-associated antigen release, but also trigger sustainable expression of cytokine interleukin-2. Notably, a synergistic antitumor effect is achieved between the process of p53 transfection and NIR-II light-activated genetic engineering of bacteria. This work proposes a facile strategy for the construction of hybrid system to achieve cascade-augmented cancer immunotherapy.

Hypoxia Reversion and STING Pathway Activation through Large Mesoporous Nanozyme for Near-Infrared-II Light Amplified Tumor Polymetallic-Immunotherapy.

cGAS/STING pathway, which is highly related to tumor hypoxia, is considered as a potential target for remodeling the immunosuppressive microenvironment of solid tumors. Metal ions, such as Mn2+, activate the cGAS/STING pathway, but their efficacy in cancer therapy is limited by insufficient effect on immunogenic tumor cell death of a single ion. Here, we evaluate the association between tumor hypoxia and cGAS/STING inhibition and report a polymetallic-immunotherapy strategy based on large mesoporous trimetal-based nanozyme (AuPdRh) coordinated with Mn2+ (Mn2+@AuPdRh) to activate cGAS/STING signaling for robust adaptive antitumor immunity. Specifically, the inherent CAT-like activity of this polymetallic Mn2+@AuPdRh nanozyme decomposes the endogenous H2O2 into O2 to relieve tumor hypoxia induced suppression of cGAS/STING signaling. Moreover, the Mn2+@AuPdRh nanozyme displays a potent near-infrared-II photothermal effect and strong POD-mimic activity; and the generated hyperthermia and •OH radicals synergistically trigger immunogenic cell death in tumors, releasing abundant dsDNA, while the delivered Mn2+ augments the sensitivity of cGAS to dsDNA and activates the cGAS-STING pathway, thereby triggering downstream immunostimulatory signals to kill primary and distant metastatic tumors. Our study demonstrates the potential of metal-based nanozyme for STING-mediated tumor polymetallic-immunotherapy and may inspire the development of more effective strategies for cancer immunotherapy.

Recent Advances in DNA-Based Nanoprobes for In vivo MiRNA Imaging.

As a post transcriptional regulator of gene expression, miRNA is closely related to many major human diseases, especially cancer. Therefore, its precise detection is very important for disease diagnosis and treatment. With the advancement of fluorescent dye and imaging technology, the focus has shifted from in vitro microRNAs (miRNA) detection to in vivo miRNA imaging. This concept review summarizes signal amplification strategies including DNAzyme catalytic reaction, hybrid chain reaction (HCR), catalytic hairpin assembly (CHA) to enhance detection signal of lowly expressed miRNAs; external stimuli of ultraviolet (UV) light or near-infrared region (NIR) light, and internal stimuli such as adenosine triphosphate (ATP), glutathione (GSH), protease and cell membrane protein to prevent nonspecific activation for the avoidance of false positive signal; and the development of fluorescent probes with emission in NIR for in vivo miRNA imaging; as well as rare earth nanoparticle based the second near-infrared window (NIR-II) nanoprobes with excellent tissue penetration and depth for in vivo miRNA imaging. The concept review also indicated current challenges for in vivo miRNA imaging including the dynamic monitoring of miRNA expression change and simultaneous in vivo imaging of multiple miRNAs.

An Integrated Nanoplatform via Dual Channel Excitation for Both Precise Fluorescence Imaging and Photodynamic Therapy of Orthotopic Breast Tumor in NIR-II Region.

Although research on photodynamic therapy (PDT) of malignant tumor has made considerable progress in recent years, it is a remaining challenge to extend PDT to the second near-infrared window (NIR-II) along with real-time and accurate NIR-II fluorescence imaging to determine drug enrichment status and achieve high treatment efficacy. In this work, lanthanide nanoparticles (Ln NPs)-based nanoplatform (LCR) equipped with photosensitizer Chlorin e6 (Ce6) and targeting molecular NH2-PEG1000-cRGDfK are developed, which can achieve NIR-II photodynamic therapy (PDT) and NIR-II fluorescence imaging by dual channel excitation. Under 808 nm excitation, Nd3+ in the outer layer can absorb the energy and transfer inward to emit strong NIR-II emissions (1064 and 1525 nm). Due to the low background noise of NIR-II light and the targeting effect of NH2-PEG1000-cRGDfK, LCR can recognize tiny tumor tissue (≈3 mm) and monitor drug distribution in vivo. Under 1530 nm excitation, internal Er3+ can be self-sensitized, generating intense upconversion emission (662 nm) that can effectively activate Ce6 for in vivo PDT due to the deep tissue penetration of NIR-II light. This study provides a paradigm of theranostic nanoplatform for both real-time fluorescence imaging and PDT of orthotopic breast tumor in NIR-II window.

Synthesis of D-A-type groups modified aza-BODIPY fluorescent dye encapsulated by amphiphilic polypeptide nanoparticles for NIR-II phototheranostics.

An innovative organic small molecule with a D-A structure was synthesized by connecting triphenylamine to BODIPY via a thiophene bridge. Triphenylamine and thiophene units ingeniously modulate the balance between steric hindrance and π-π interactions around the flat aza-BODIPY core. The molecule exhibits near-infrared fluorescence absorption and emits at roughly 1100 nm, featuring a significant Stokes shift. Both the molecule and its nanoparticles demonstrate high stability and achieve a remarkable 35 % photothermal conversion efficiency when conjugated with the P(OEGMA)20-P(Asp)14 copolymer. In vitro assessments show low dark toxicity and outstanding biocompatibility. Moreover, in vivo studies and photothermal therapy in mice indicate substantial tumor shrinkage and reduced recurrence, confirming its potential in cancer treatment. These results highlight the promise of this organic molecule and its nanoparticles for NIR-II imaging-guided photothermal therapy, introducing a novel approach to phototheranostic applications for cancer management.

A Small-Molecule NIR-II Probe for the Diagnosis of Hemorrhagic Diseases.

Numerous hemorrhagic disorders, particularly those presenting deep hemorrhage, pose diagnostic challenges, often leading to delayed treatment and severe outcomes. Near-infrared (NIR)-II fluorescence imaging offers advantages such as deep tissue penetration, real-time visualization, and a high signal-to-background ratio, making it highly suitable for diagnosing hemorrhagic diseases. In this study, an NIR-II fluorescent probe LJ-2P carrying carboxylic and phosphoric acid groups is successfully applied for imaging hemorrhagic diseases. LJ-2P demonstrates a strong affinity for fibrinogen and fibrin clots both computationally and experimentally, thus exhibiting increased brightness upon coagulation. As compared to Indocyanine Green, LJ-2P provides a longer imaging window, higher imaging specificity, and signal-to-background ratio, as well as superior photobleaching resistance in three disease models: gastric, pulmonary, and cerebral hemorrhages. These results reveal that LJ-2P demonstrates enhanced imaging capabilities, enabling precise identification of hemorrhagic sites.

H2S-Responsive NIR-II Fluorescent Nanozyme that Regulates Tumor Microenvironment for Activatable Synergistic CO Therapy/Catalytic Therapy/Immunotherapy.

Nanozyme catalytic therapy triggered by the tumor microenvironment (TME)-responsive enzyme-like catalytic activities is an emerging approach for tumor treatment. However, the poor catalytic efficiency of nanozymes in tumors and the toxic side effects on normal tissues limit their further development, primarily due to the limited uptake and penetration depth of nanozyme in tumor tissues. Here, a tumor-targeting TME and electric field stimuli-responsive nanozyme (AgPt@CaCO3-FA) is developed, which is capable of catalyzing the generation of ROS to induce cell death and releasing carbon monoxide (CO) specifically in tumor tissues for on-demand CO therapy and immunotherapy. Benefiting from the endogenous H2S activated NIR-II fluorescence (FL) imaging guidance, AgPt@CaCO3-FA can be delivered into the deeper site of tumor tissues resulted from the TME regulation via generated CO during the electrolysis process to improve the catalytic efficiency of nanozymes in tumors. Moreover, CO effectively relieve immunosuppression TME via reeducating tumor-supportive M2-like macrophages to tumoricidal M1-like macrophages and induce mitochondrial dysfunction by reducing mitochondrial membrane potential, triggering tumor cells apoptosis. The enzyme-like activities combined with CO therapy arouse distinct immunogenic cell death (ICD) effect. Therefore, AgPt@CaCO3-FA permits synergistic CO gas, catalytic therapy and immunotherapy, effectively eradicating orthotopic breast tumors and preventing tumor metastasis and recurrence.

Gold Nano Frameworks with Mesopores for Synergistic Immune-Thermal Therapy in Hepatic Carcinoma: A Paradigm Shift in Immune Checkpoint Blockade.

Immune checkpoint blockade (ICB) therapy, while showing promise in various cancers, exhibits limited effectiveness in hepatic carcinoma due to the tumor's immunosuppressive microenvironment (TME) and challenges associated with immune cell infiltration. Efforts to transform the "cold" TME into an "inflamed" state, notably through chemo-immunotherapy, have sparked interest due to their potential to induce immunogenic cell death and augment the infiltration of cytotoxic T lymphocytes (CTLs). Nonetheless, the efficacy of chemo-immunotherapy is often compromised by suboptimal pharmacokinetics, poor tumor accumulation, and off-target toxicity. Herein, in response, we introduce an innovative, milder thermal therapeutic approach leveraging gold nano frameworks with mesopores for the targeted delivery of the immunostimulant imiquimod and NIR-II photothermal therapy. This strategy employs targeted molecule modifications to ensure precise tumor targeting, guided by photoacoustic imaging. Subsequent to mild thermal treatment, there is a release of immunogenic proteins (CRT and HSP90), enhancing tumor immunogenicity. Assisted by imiquimod, substantial CTL infiltration occurs, accompanied by pro-inflammatory factor release (TNF-α, IL-6), transforming M2 macrophages into the M1 phenotype. Ultimately, the proposed strategy combines PD-L1/PD-1 blockade, imiquimod and mild thermal treatment to synergistically enhance tumor immunogenicity, remodel the TME, and restrain hepatic carcinoma, making strides in ICB synergistic immune-thermal therapy.

NIR-II Responsive Fe-Doped Carbon Nanoparticles for Photothermal-Enhanced Chemodynamic Synergistic Oncotherapy.

Phototherapy has demonstrated substantial development because in the second near-infrared (NIR-II) window it has a larger tissue penetration and fewer adverse consequences. In this work, a particular kind of NIR-II responsive Fe-doped carbon nanoparticles (FDCNs) is synthesized using a one-pot hydrothermal method for combined photothermal and chemodynamic therapy. The mesoporous nanostructure of FDCN, which has a size distribution that exceeds 225 nm, allows for effective acidification. The iron ions released from these nanoparticles can catalyze the decomposition of hydrogen peroxide (H2O2) into hydroxyl radical (•OH) for chemodynamic therapy (CDT). In addition to their CDT utility, FDCN can effectively adsorb and transform 1064 nm light into local heat, achieving a photothermal conversion efficacy (PCE) of 36.3%. This dual functionality not only allows for the direct eradication of cancer cells through photothermal therapy (PTT) but also enhances the chemodynamic reaction, creating a synergistic effect that amplifies the therapeutic outcome. The FDCN has demonstrated remarkable anticancer activity in both cellular and animal tests without incurring major systemic toxicity. This suggests that the compound has great promise for use in clinical cancer therapy.

Enhancing Root Canal Therapy with NIR-II Semiconducting Polymer AIEgen and Low-Concentration Sodium Hypochlorite Synergy.

Despite significant efforts to eliminate bacterial biofilm within root canals, achieving effective disinfection remains challenging due to the complex anatomy and limitations of disinfectants. In this study, a second near-infrared (NIR-II) semiconducting polymer with aggregation-induced emission (AIE) properties, named PIDT-TBT, is deliberately designed and synthesized. This proposes an AIE luminogen-based sterilization strategy in synergy with a low concentration of sodium hypochlorite (NaClO). Water-dispersible PIDT-TBT nanoparticles (NPs) are prepared, demonstrating good biocompatibility, as well as photothermal and photodynamic properties. Subsequent antibacterial tests show that PIDT-TBT NPs exhibit excellent bactericidal effects against three bacterial strains: Staphylococcus aureus, Streptococcus mutans, and Enterococcus faecalis, upon 808 nm laser irradiation. In synergy with a low concentration of NaClO (0.5%) solution, PIDT-TBT NPs significantly improves the outcome of root canal treatment under 808 nm laser irradiation in a human extracted tooth root canal infection model. Additionally, it is found that PIDT-TBT NPs combine with a low concentration of NaClO solution could safely dissolve dentin debris and further increase the efficiency of root canal preparation by altering the elemental composition of the inner root canal wall.

Real-time detection and resection of sentinel lymph node metastasis in breast cancer through a rare earth nanoprobe based NIR-IIb fluorescence imaging.

Sentinel lymph node (SLN) biopsy is a commonly employed procedure for the routine assessment of axillary involvement in patients with breast cancer. Nevertheless, conventional SLN mapping cannot reliably distinguish the presence and absence of metastatic disease. Additionally, the complex anatomical structures and lymphatic drainage patterns surrounding tumor sites pose challenges to the sensitivity of the near-infrared fluorescence imaging with subcutaneously injected probes. To identifying the SLN metastases, we developed a novel nanoprobe for in vivo fluorescence imaging within the second near-infrared (NIR-II) range. This nanoprobe utilizes rare-earth nanoparticles (RENPs) to emit bright fluorescence at 1525 nm and is conjugated with tumor-targeted hyaluronic acid (HA) to facilitate the detection of metastatic SLN. Upon intravenous administration, RENPs@HA effectively migrated to SLNs and selectively entered metastatic breast tumor cells through CD44-mediated endocytosis. The RENPs@HA nanoprobes exhibited rapid accumulation in metastatic inguinal lymph nodes in mouse model, displaying a 5.8-fold-stronger fluorescence intensity to that observed in normal SLNs. Consequently, these nanoprobes effectively differentiate metastatic SLNs from normal SLNs. Importantly, the probes accurately detected micrometastases. These findings underscore the potential of RENPs@HA for real-time visualization and screening of SLNs metastasis.

Croconaine-based NIR-II fluorescence imaging-guided tumor photothermal therapy induces long-term antitumor immune memory.

Photothermal therapy (PTT) for cancers guided by optical imaging has recently shown great potential for precise diagnosis and efficient therapy. The second near-infrared window (NIR-II, 1000-1700 nm) fluorescence imaging (FLI) is highly desirable owing to its good spatial and temporal resolution, deep tissue penetration, and negligible tissue toxicity. Organic small molecules are attractive as imaging and treatment agents in biomedical research because of their low toxicity, fast clearance rate, diverse structures, ease of modification, and excellent biocompatibility. Various organic small molecules have been investigated for biomedical applications. However, there are few reports on the use of croconaine dyes (CRs), especially NIR-II emission CRs. To our knowledge, there have been no prior reports of NIR-II emissive small organic photothermal agents (SOPTAs) based on CRs. Herein, we report a croconaine dye (CR-TPE-T)-based nanoparticle (CR NP) with absorption and fluorescence emission in the NIR-I and NIR-II windows, respectively. The CR NPs exhibited intense NIR absorption, outstanding photothermal properties, and good biological compatibility. In vivo studies showed that CR NPs not only achieved real-time, noninvasive NIR-II FLI of tumors, but also induced significant tumor ablation with laser irradiation guided by imaging, without apparent side effects, and promoted the formation of antitumor immune memory in a colorectal cancer model. In addition, the CR NPs displayed efficient inhibition of breast tumor growth, improved longevity of mice and triggered efficient systemic immune responses, which further inhibited tumor metastasis to the lungs. Our study demonstrates the great potential of CRs as therapeutic agents in the NIR-II region for cancer diagnosis.

The biological applications of near-infrared optical nanomaterials in atherosclerosis.

PURPOSE OF REVIEW: Atherosclerosis, a highly pathogenic and lethal disease, is difficult to locate accurately via conventional imaging because of its scattered and deep lesions. However, second near-infrared (NIR-II) nanomaterials show great application potential in the tracing of atherosclerotic plaques due to their excellent penetration and angiographic capabilities. RECENT FINDINGS: With the development of nanotechnology, among many nanomaterials available for the visual diagnosis and treatment of cardiovascular diseases, optical nanomaterials provide strong support for various biomedical applications because of their advantages, such as noninvasive, nondestructive and molecular component imaging. Among optical nanomaterials of different wavelengths, NIR-II-range (900 ~ 1700 nm) nanomaterials have been gradually applied in the visual diagnosis and treatment of atherosclerosis and other vascular diseases because of their deep biological tissue penetration and limited background interference. This review explored in detail the prospects and challenges of the biological imaging and clinical application of NIR-II nanomaterials in treating atherosclerosis.

Pt/Pd dual-modified porphyrin metal-organic frameworks for NIR-II photothermal-enhanced photodynamic/catalytic therapy.

Photodynamic therapy (PDT) and catalytic therapy were promising treatment modes, but tumor hypoxia and poor catalytic activity severely limited their efficacies. Herein, using a porphyrin metal-organic framework (PCN-224) as nanocarrier, a platinum/palladium (Pt/Pd) dual-modified PCN-224 nanoprobe (PCN-224-Pt@Pd) with strong peroxidase (POD)/catalase (CAT)-like activities was developed, achieving photothermal-promoted PDT/catalytic therapy. Compared with single ultrasmall Pt modifying, CAT-like activity of Pt/Pd dual-modifying increased oxygen concentration from 6.24 to 9.35 mg/L, which improved singlet oxygen (1O2) yield from 63.8 % to 82.9 %. Moreover, POD-like activity of Pt/Pd dual-modifying significantly accelerated hydroxyl radicals (·OH) generation. Importantly, PCN-224-Pt@Pd possessed near-infrared II (NIR-II) photothermal effect with a high efficiency (55.6 %), which further promoted ·OH production. Under combined therapy of PCN-224-Pt@Pd, the cell survival rate greatly reduced to 5.8 %, and the tumors were cured, suggesting NIR-II photothermal-enhanced PDT/catalytic therapy.

Reactive Oxygen Species-Responsive Nanoparticle Delivery of Small Interfering Ribonucleic Acid Targeting Olfactory Receptor 2 for Atherosclerosis Theranostics.

Atherosclerosis (AS) is a chronic inflammatory disorder characterized by arterial intimal lipid plaques. Small interfering ribonucleic acid (siRNA)-based therapies, with their ability to suppress specific genes with high targeting precision and minimal side effects, have shown great potential for AS treatment. However, targets of siRNA therapies based on macrophages for AS treatment are still limited. Olfactory receptor 2 (Olfr2), a potential target for plaque formation, was discovered recently. Herein, anti-Olfr2 siRNA (si-Olfr2) targeting macrophages was designed, and the theranostic platform encapsulating si-Olfr2 to target macrophages within atherosclerotic lesions was also developed, with the aim of downregulating Olfr2, as well as diagnosing AS through photoacoustic imaging (PAI) in the second near-infrared (NIR-II) window with high resolution. By utilization of a reactive oxygen species (ROS)-responsive nanocarrier system, the expression of Olfr2 on macrophages within atherosclerotic plaques was effectively downregulated, leading to the inhibition of NLR family pyrin domain containing 3 (NLRP3) inflammasome activation and interleukin-1 ß (IL-1ß) secretion, thereby reducing the formation of atherosclerotic plaques. As manifested by decreased Olfr2 expression, the lesions exhibited a significantly alleviated inflammatory response that led to reduced lipid deposition, macrophage apoptosis, and a noticeable decrease in the necrotic areas. This study provides a proof of concept for evaluating the theranostic nanoplatform to specifically deliver si-Olfr2 to lesional macrophages for AS diagnosis and treatment.

Hyaluronic acid modified indocyanine green nanoparticles: a novel targeted strategy for NIR-II fluorescence lymphatic imaging.

The lymphatic system, alongside blood circulation, is crucial for maintaining bodily equilibrium and immune surveillance. Despite its importance, lymphatic imaging techniques lag behind those for blood circulation. Fluorescence imaging, particularly in the near-infrared-II (NIR-II) region, offers promising capabilities with centimeter-scale tissue penetration and micron-scale spatial resolution, sparking interest in visualizing the lymphatic system. Although indocyanine green (ICG) has been approved by the Food and Drug Administration (FDA) for use as a near-infrared-I (NIR-I) region fluorescent dye, its limitations include shallow penetration depth and low signal-to-noise ratio. Research suggests that ICG's fluorescence emission tail in the second near-infrared window holds potential for high-quality NIR-II imaging. However, challenges like short circulation half-life and concentration-dependent aggregation hinder its wider application. Here we developed HA@ICG nanoparticles (NPs), a superior ICG-based NIR-II fluorescent probe with excellent biocompatibility, prolonging in vivo imaging, and enhancing photostability compared to ICG alone. Leveraging LYVE-1, a prominent lymphatic endothelial cell receptor that binds specifically to hyaluronic acid (HA), our nanoprobes exhibit exceptional performance in targeting lymphatic system imaging. Moreover, our findings demonstrate the capability of HA@ICG NPs for capillary imaging, offering a means to assess local microcirculatory blood supply. These compelling results underscore the promising potential of HA@ICG NPs for achieving high-resolution bioimaging of nanomedicines in the NIR-II window.

A Self-Cascade Penetrating Brain Tumor Immunotherapy Mediated by Near-Infrared II Cell Membrane-Disrupting Nanoflakes via Detained Dendritic Cells.

Immunotherapy can potentially suppress the highly aggressive glioblastoma (GBM) by promoting T lymphocyte infiltration. Nevertheless, the immune privilege phenomenon, coupled with the generally low immunogenicity of vaccines, frequently hampers the presence of lymphocytes within brain tumors, particularly in brain tumors. In this study, the membrane-disrupted polymer-wrapped CuS nanoflakes that can penetrate delivery to deep brain tumors via releasing the cell-cell interactions, facilitating the near-infrared II (NIR II) photothermal therapy, and detaining dendritic cells for a self-cascading immunotherapy are developed. By convection-enhanced delivery, membrane-disrupted amphiphilic polymer micelles (poly(methoxypoly(ethylene glycol)-benzoic imine-octadecane, mPEG-b-C18) with CuS nanoflakes enhances tumor permeability and resides in deep brain tumors. Under low-power NIR II irradiation (0.8 W/cm2), the intense heat generated by well-distributed CuS nanoflakes actuates the thermolytic efficacy, facilitating cell apoptosis and the subsequent antigen release. Then, the positively charged polymer after hydrolysis of the benzoic-imine bond serves as an antigen depot, detaining autologous tumor-associated antigens and presenting them to dendritic cells, ensuring sustained immune stimulation. This self-cascading penetrative immunotherapy amplifies the immune response to postoperative brain tumors but also enhances survival outcomes through effective brain immunotherapy.

Cytometry in the Short-Wave Infrared.

Cytometry plays a crucial role in characterizing cell properties, but its restricted optical window (400-850 nm) limits the number of stained fluorophores that can be detected simultaneously and hampers the study and utilization of short-wave infrared (SWIR; 900-1700 nm) fluorophores in cells. Here we introduce two SWIR-based methods to address these limitations: SWIR flow cytometry and SWIR image cytometry. We develop a quantification protocol for deducing cellular fluorophore mass. Both systems achieve a limit of detection of ∼0.1 fg cell-1 within a 30 min experimental time frame, using individualized, high-purity (6,5) single-wall carbon nanotubes as a model fluorophore and macrophage-like RAW264.7 as a model cell line. This high-sensitivity feature reveals that low-dose (6,5) serves as an antioxidant, and cell morphology and oxidative stress dose-dependently correlate with (6,5) uptake. Our SWIR cytometry holds immediate applicability for existing SWIR fluorophores and offers a solution to the issue of spectral overlapping in conventional cytometry.

NIR-II-Responsive Versatile Nanozyme Based on H2O2 Cycling and Disrupting Cellular Redox Homeostasis for Enhanced Synergistic Cancer Therapy.

Disturbing cellular redox homeostasis within malignant cells, particularly improving reactive oxygen species (ROS), is one of the effective strategies for cancer therapy. The ROS generation based on nanozymes presents a promising strategy for cancer treatment. However, the therapeutic efficacy is limited due to the insufficient catalytic activity of nanozymes or their high dependence on hydrogen peroxide (H2O2) or oxygen. Herein, we reported a nanozyme (CSA) based on well-defined CuSe hollow nanocubes (CS) uniformly covered with Ag nanoparticles (AgNPs) to disturb cellular redox homeostasis and catalyze a cascade of intracellular biochemical reactions to produce ROS for the synergistic therapy of breast cancer. In this system, CSA could interact with the thioredoxin reductase (TrxR) and deplete the tumor microenvironment-activated glutathione (GSH), disrupting the cellular antioxidant defense system and augmenting ROS generation. Besides, CSA possessed high peroxidase-mimicking activity toward H2O2, leading to the generation of various ROS including hydroxyl radical (•OH), superoxide radicals (•O2-), and singlet oxygen (1O2), facilitated by the Cu(II)/Cu(I) redox and H2O2 cycling, and plentiful catalytically active metal sites. Additionally, due to the absorption and charge separation performance of AgNPs, the CSA exhibited excellent photothermal performance in the second near-infrared (NIR-II, 1064 nm) region and enhanced the photocatalytic ROS level in cancer cells. Owing to the inhibition of TrxR activity, GSH depletion, high peroxidase-mimicking activity of CSA, and abundant ROS generation, CSA displays remarkable and specific inhibition of tumor growth.