Memory-like response in platelet attenuates platelet hyperactivation in arterial thrombosis.

Recent studies showed that in responding of pathogens stimulation, immune cells and other cells display memory-like effects. Platelets are primary effectors of hemostasis and thrombosis which also participate in immune responses. However, there is no relevant research on whether memory-like effect exists in platelets. In our study after recovery from repetitive LPS stimulus, platelets aggregation, diffusion and clot retraction exhibit a significant reduction. It proves that memory-like response could be aroused in platelets. Furthermore, in the mouse arterial thrombosis model, LPS pretreated platelets showed lower integrin activation, shorter thrombus length and longer occlusion time, indicating that the memory-like response of platelet could alleviate arterial thrombosis. Moreover, memory-like response of platelets was also found to be related to PI3K/AKT signaling pathway. The decreased mitochondrial DNA methylation reveal that platelet memory-like responses may be produced from epigenetic reprogramming. Our research proves for the first time that memory-like response in platelets protects mice from arterial thrombosis, extends the understanding of trained memory.

Amphiphilic Triblock Copolymer Prodrug for Tumor-Specific pH/Reduction Dual-Triggered Drug Delivery: Effect of Self-Assembly Behaviors.

Diblock copolymer-based prodrugs have been widely designed for tumor treatment after self-assembly; however, premature drug leakage could not be ignored because their hydrophobic prodrug cores were directly exposed to the media. Here, an amphiphilic triblock copolymer prodrug with a hydrophilic PEG block, a pH-sensitive poly(2-(diisopropylamino)ethyl methacrylate) (PDPA) block, and a hydrophobic reduction-cleavable prodrug block was synthesized for tumor-specific pH/reduction dual-triggered drug delivery, via the successive RAFT polymerization of DPA and a DOX-based monomer (MAL-DOX) with a PEG-based macro-CTA. The core-shell and core-shell-corona nanoparticles could be obtained by one-step and two-step self-assembly. With the pH-sensitive gatekeeper formed by the PDPA block, the core-shell-corona nanoparticles possessed a smaller diameter with narrow distribution and better drug release with lower drug leakage. MTT assays demonstrated the selective cytotoxicity of the core-shell-corona nanoparticles to the cancer cells was dose-dependent because of the reduction-cleavable prodrug. The negligible drug leakage and selective cytotoxicity to cancer cells endow the proposed core-shell-corona prodrug nanoparticles with promising potential for tumor treatment without toxic side effects on the normal cells.

Self-assembled metal-polyphenolic based multifunctional nanomedicine to improve therapy treatment of pancreatic cancer by inhibition of glutamine metabolism.

Cancer poses a significant threat to human health and life. Chemotherapy, immunotherapy and chemodynamic therapy (CDT) are effective treatments for cancer. However, the presence of metabolic reprogramming via glutamine in tumor cells limits their therapeutic effectiveness. Herein, we propose an effective assembly strategy to synthesize a novel metal-polyphenolic based multifunctional nanomedicine (Fe-DBEF) containing Pluronic F127 stable ferric ion crosslinked epigallocatechin gallate (EGCG) nanoparticles loaded with GLS1 inhibitor bis-2-(5-phenylacetamino-1,3,4-thiadiazole-2-yl) ethyl sulfide (BPTES) and chemotherapy drug doxorubicin (DOX). Our study demonstrates that Fe-DBEF nanomedicine exhibits high efficiency anti-proliferation properties in pancreatic cancer through a combination of in vitro cell experiments, human organoid experiments and KPC animal experiments. Notably, Fe-DBEF nanomedicine can reduce the production of glutathione (GSH) in tumor cells, thereby reducing their resistance to ROS therapy. Additionally, excessive ROS production also aggravates DNA damage caused by DOX, synergistically sensitizing chemotherapy and promoting apoptosis for efficient treatment of pancreatic cancer. Overall, our findings suggest that inhibiting glutamine metabolism to increase the sensitivity of chemotherapy/CDT using metal-polyphenolic based multifunctional nanomedicine provides a promising combination of multiple therapeutic means for treating pancreatic cancer.

One-Step Fabrication of Coconut-Like Capsules via Competitive Reactions at an All-Aqueous Interface for Enzyme Immobilization.

A concept of interfacial competitive reaction between biomineralization and alginate gelation at an all-aqueous single-emulsion droplet interface to prepare robust coconut-like capsules (inner hard wall and outer soft wall) is developed. The concept is further applied for enzyme immobilization with high encapsulation efficiency, enzyme loading, mass transfer coefficient, and recyclability. The thickness and swelling properties of the shell are simply tunable by a competitive reaction. Our platform may open a green, facile, and efficient way to prepare organic-inorganic hybrid sustainable materials with tailored compositions and structures.

Xanthohumol alleviates oxidative stress and impaired autophagy in experimental severe acute pancreatitis through inhibition of AKT/mTOR.

Severe acute pancreatitis (SAP) is a lethal gastrointestinal disorder, yet no specific and effective treatment is available. Its pathogenesis involves inflammatory cascade, oxidative stress, and autophagy dysfunction. Xanthohumol (Xn) displays various medicinal properties, including anti-inflammation, antioxidative, and enhancing autophagic flux. However, it is unclear whether Xn inhibits SAP. This study investigated the efficacy of Xn on sodium taurocholate (NaT)-induced SAP (NaT-SAP) in vitro and in vivo. First, Xn attenuated biochemical and histopathological responses in NaT-SAP mice. And Xn reduced NaT-induced necrosis, inflammation, oxidative stress, and autophagy impairment. The mTOR activator MHY1485 and the AKT activator SC79 partly reversed the treatment effect of Xn. Overall, this is an innovative study to identify that Xn improved pancreatic injury by enhancing autophagic flux via inhibition of AKT/mTOR. Xn is expected to become a novel SAP therapeutic agent.

Endogenous SIRT6 in platelets negatively regulates platelet activation and thrombosis.

Thromboembolism resulting from platelet dysfunction constitutes a significant contributor to the development of cardiovascular disease. Sirtuin 6 (SIRT6), an essential NAD+-dependent enzyme, has been linked to arterial thrombosis when absent in endothelial cells. In the present study, we have confirmed the presence of SIRT6 protein in anucleated platelets. However, the precise regulatory role of platelet endogenous SIRT6 in platelet activation and thrombotic processes has remained uncertain. Herein, we present compelling evidence demonstrating that platelets isolated from SIRT6-knockout mice (SIRT6-/-) exhibit a notable augmentation in thrombin-induced platelet activation, aggregation, and clot retraction. In contrast, activation of SIRT6 through specific agonist treatment (UBCS039) confers a pronounced protective effect on platelet activation and arterial thrombosis. Moreover, in platelet adoptive transfer experiments between wild-type (WT) and SIRT6-/- mice, the loss of SIRT6 in platelets significantly prolongs the mean thrombus occlusion time in a FeCl3-induced arterial thrombosis mouse model. Mechanistically, we have identified that SIRT6 deficiency in platelets leads to the enhanced expression and release of proprotein convertase subtilisin/kexin type 9 (PCSK9), subsequently activating the platelet activation-associated mitogen-activated protein kinase (MAPK) signaling pathway. These findings collectively unveil a novel protective role of platelet endogenous SIRT6 in platelet activation and thrombosis. This protective effect is, at least in part, attributed to the inhibition of platelet PCSK9 secretion and mitogen-activated protein kinase signaling transduction. Our study provides valuable insights into the intricate interplay between SIRT6 and platelet function, shedding light on potential therapeutic avenues for managing thrombotic disorders.

A selective, sensitive, colorimetric, and fluorescence probe for relay recognition of fluoride and Cu(II) ions with "off-on-off" switching in ethanol-water solution.

Anion to cation relay recognition was designed and realized for the first time with sequence specificity (F(-)→Cu(2+)) via a fluorescence "off-on-off" mechanism. Probe 1 was a highly selective, sensitive, and turn-on chemodosimeter for F(-) through a specific cyclization reaction triggered by the strong affinity of fluoride toward silicon with a significant change of fluorescence color in both ethanol and ethanol-water (1:1, v/v) solution. Fluorescence enhancement factors were dramatic: 833-fold in ethanol and 164-fold in ethanol-water (1:1, v/v) solution, respectively. The in situ system generated from the sensing of F(-) showed good relay recognition ability for Cu(2+) via fast fluorescence quenching by the formation of a 1:1 complex in ethanol-water (1:1, v/v) solution. The isolated pure compound 2 also exhibited high selectivity toward Cu(2+) in PBS buffer (pH = 7.0) solution. The origin of this sequence specificity of fluorescence recognition was disclosed through the crystal or optimized structures and DFT calculations of corresponding compounds.

Compartmentalized Aqueous-in-Aqueous Droplets for Flow Biocatalysis.

Compartmentalized bioreactions are vital for living cells to regulate biological events since they facilitate isolated yet orchestrated reactions and releases of biological molecules. Engineering bioreactions in compartmentalized droplet bioreactors not only promotes understanding of biological cells but also enhances control in synthetic biology systems. A typical droplet bioreactor is enclosed by impermeable water-in-oil interfaces, which inhibit the reaction rate with the accumulation of aqueous products. This work constructs aqueous two-phase system (ATPS) droplet bioreactors featuring selectively permeable interfaces, which are capable of sequestering reagents in aqueous droplets while constantly releasing products into the aqueous surroundings. Benefiting from this selective permeability, the proposed droplet bioreactor achieves a conversion rate up to 63.2% compared to the 17.9% from the impermeable aqueous-in-oil droplet reactor via coupled reaction-separation. More importantly, it is revealed that uniform aqueous-in-aqueous droplet clusters by microfluidics exhibit an up to 6-fold reaction rate enhancement compared to non-microfluidic ATPS reactors, indicating a unique flow interface effect in droplet clusters. This work offers a new route to allow enzymatic reactions to benefit from efficient flow chemistry via optimized aqueous-aqueous interfaces.

Deoxyarbutin attenuates severe acute pancreatitis via the HtrA2/PGC-1α pathway.

Severe acute pancreatitis (SAP) is an inflammatory disorder of the exocrine pancreas associated with high morbidity and mortality. SAP has been proven to trigger mitochondria dysfunction in the pancreas. We found that Deoxyarbutin (dA) recovered impaired mitochondrial function. High-temperature requirement protein A2 (HtrA2), a mitochondrial serine protease upstream of PGC-1α, is charge of quality control in mitochondrial homeostasis. The molecular docking study indicated that there was a potential interaction between dA and HtrA2. However, whether the protective effect of dA against SAP is regulated by HtrA2/PGC-1α remains unknown. Our study in vitro showed that dA significantly reduced the necrosis of primary acinar cells and reactive oxygen species (ROS) accumulation, recovered mitochondrial membrane potential (ΔΨm) and ATP exhaustion, while UCF-101 (HtrA2 inhibitor), and SR-18292 (PGC-1α inhibitor) eliminated the protective effect of dA. Moreover, HtrA2 siRNA transfection efficiently blocked the protective of dA on HtrA2/PGC-1α pathway in 266-6 acinar cells. Meanwhile, dA also decreased LC3II/I ration, as well as p62, and increased Parkin expression, while UCF-101 and Bafilomycin A1 (autophagy inhibitor) reversed the protective effect of dA. Our study in vivo confirmed that dA effectively alleviated severity of SAP by reducing pancreatic edema, plasma amylase, and lipase levels and improved the HtrA2/PGC-1α pathway. Therefore, this is the first study to identify that dA inhibits pancreatic injury caused by oxidative stress, mitochondrial dysfunction, and impaired autophagy in a HtrA2/PGC-1α dependent manner.

Activation of TLR4 induces severe acute pancreatitis-associated spleen injury via ROS-disrupted mitophagy pathway.

Severe acute pancreatitis (SAP) is complicated by systemic inflammatory response syndrome and multiple organ dysfunction, the disease will eventually result in death in almost half of the case. The spleen, as the largest immune organ adjacent to the pancreas, is prone to damage in SAP, thereby aggravating the damage of other organs and increasing mortality. However, to date, the research on the mechanism and treatment of spleen injury caused by SAP is still in its infancy. Herein, we investigated the mechanism of spleen injury, and explored the application potential of tuftsin for relieving spleen damage in SAP mice. Firstly, SAP mice model was constructed via the retrograde infusion of 3.5 % sodium taurocholate into the biliopancreatic duct. Then, we proved that the up-regulation of Toll-like receptor 4 (TLR4) in spleen would lead to the accumulation of reactive oxygen species (ROS) and mitochondrial dysfunction under SAP conditions. The splenic ROS and mitochondrial dysfunction could be improved by N-acetylcysteine (NAC) treatment or knocking out TLR4 in SAP mice. Meanwhile, we found that NAC treatment could also improve the autophagy of spleen tissue, suggesting that splenic ROS may affect impaired autophagy, causing the accumulation of damaged mitochondria, aggravating spleen damage. Furthermore, we verified the mechanism of spleen injury is caused by splenic ROS affecting PI3K/p-AKT/mTOR pathway-mediated autophagy. In addition, we detected the spleen injury caused by SAP could decrease the concentration of tuftsin in the serum of mice. Whereas, exogenous supplementation of tuftsin ameliorated the pathological damage, ROS accumulation, impaired autophagy, inflammation expression and apoptosis in damaged spleen. In summary, we verified the new mechanism of SAP-caused spleen damage that TLR4-induced ROS provoked mitophagy impairment and mitochondrial dysfunction in spleen via PI3K/p-AKT mTOR signaling, and the application potential of tuftsin in treating spleen injury, which might expand novel ideas and methods for the treatment of pancreatitis.

STING up-regulates VEGF expression in oxidative stress-induced senescence of retinal pigment epithelium via NF-κB/HIF-1α pathway.

AIM: Aging-related dysfunction of retinal pigment epithelium (RPE) is the main pathogenic factors for pathological angiogenesis due to dysregulated vascular endothelial growth factor (VEGF) in retinal vascular diseases such as age-related macular degeneration (AMD) and diabetic retinopathy (DR). However, the molecular mechanism behind the up-regulation of VEGF in senescent RPE is still blurred. MATERIALS AND METHODS: As oxidative damage is the key cause of RPE dysfunction, we employed a model of oxidative stress-induced premature senescence of ARPE-19 to explore the effect of senescent RPE on VEGF. KEY FINDINGS: We reported that senescent ARPE-19 up-regulated VEGF expression under both short-term and prolonged H2O2 treatment, accompanying with increased HIF-1α, the key mediator of VEGF. STING signaling, which could be activated by oxidative stress-damaged DNA, was also observed to be increased in senescent ARPE-19 treated with H2O2. And the inhibition of STING significantly reduced HIF-1α expression to alleviate the up-regulation of VEGF. NF-κB was also shown to be involved in the regulation of VEGF in senescent ARPE-19 in response to STING signaling. Furthermore, oxidative stress impaired the lysosomal clearance of damaged DNA to enhance STING signaling, thereby up-regulating VEGF expression in senescent RPE. SIGNIFICANCE: Our data provide evidence that STING plays an important role in VEGF regulation in senescent RPE induced by oxidative stress.

Tuftsin ameliorates splenic inflammatory injury by promoting neuropilin-1 in severe acute pancreatitis.

Severe acute pancreatitis (SAP)-associated spleen injury causing immune disturbances aggravates organs injuries, which contributes to higher mortality rate. However, there are no effective drugs to cure SAP-induced spleen injury. Here, we found that Tuftsin (TN) is effective for ameliorating SAP-induced pathological damage and inflammation of spleen, mainly via alleviating mitochondrial dysfunction, oxidative stress, ATP depletion and the expression of pro-inflammatory factors. We further found that TN promoted anti-inflammatory macrophage phenotype M2 via up-regulating NRP1 on macrophage in spleen during SAP. Meanwhile, EG00229 (an inhibitor of NRP1 bound to TN) weakened TN's therapeutic effect in SAP-associated spleen injury. And EG00229 also inhibited M2 macrophage, leading to increasing inflammasome formation. Additionally, EG00229 reduced the protective efficiency of TN on mitochondrial dysfunction, and inflammation injury via NRP1 in spleen caused by SAP. Similarly, siRNA-Nrp1 into macrophage also prevented TN's inhibition on apoptosis. These findings reveal that TN alleviates SAP-induced spleen injury by promoting NRP1.

PD-L1 Regulates Platelet Activation and Thrombosis via Caspase-3/GSDME Pathway.

Platelets play a central role in hemostasis and thrombosis, regulating the occurrence and development of thrombotic diseases, including ischemic stroke. Programmed death ligand 1 (PD-L1) has recently been detected in platelet, while the function of PD-L1 in platelets remain elusive. Our data reveal a novel mechanism for the role of PD-L1 on platelet activation and arterial thrombosis. PD-L1 knockout does not affect platelet morphology, count, and mean volume under homeostasis and without risk of bleeding, which inhibits platelet activation by suppressing outside-in-activation of integrin by downregulating the Caspase-3/GSDME pathway. Platelet adoptive transfer experiments demonstrate that PD-L1 knockout inhibits thrombosis. And the absence of PD-L1 improves ischemic stroke severity and increases mice survival. Immunohistochemical staining of the internal structure of the thrombus proves that PD-L1 enhances the seriousness of the thrombus by inhibiting platelet activation. This work reveals a regulatory role of PD-L1 on platelet activation and thrombosis while providing novel platelet intervention strategies to prevent thrombosis.

Drug D, a Diosgenin Derive, Inhibits L-Arginine-Induced Acute Pancreatitis through Meditating GSDMD in the Endoplasmic Reticulum via the TXNIP/HIF-1α Pathway.

Acute pancreatitis (AP) is one of the most common causes of hospitalization for gastrointestinal diseases, with high morbidity and mortality. Endoplasmic reticulum stress (ERS) and Gasdermin D (GSDMD) mediate AP, but little is known about their mutual influence on AP. Diosgenin has excellent anti-inflammatory and antioxidant effects. This study investigated whether Diosgenin derivative D (Drug D) inhibits L-arginine-induced acute pancreatitis through meditating GSDMD in the endoplasmic reticulum (ER). Our studies were conducted in a mouse model of L-arginine-induced AP as well as in an in vitro model on mouse pancreatic acinar cells. The GSDMD accumulation in ER was found in this study, which caused ERS of acinar cells. GSDMD inhibitor Disulfiram (DSF) notably decreased the expression of GSDMD in ER and TXNIP/HIF-1α signaling. The molecular docking study indicated that there was a potential interaction between Drug D and GSDMD. Our results showed that Drug D significantly inhibited necrosis of acinar cells dose-dependently, and we also found that Drug D alleviated pancreatic necrosis and systemic inflammation by inhibiting the GSDMD accumulation in the ER of acinar cells via the TXNIP/HIF-1α pathway. Furthermore, the level of p-IRE1α (a marker of ERS) was also down-regulated by Drug D in a dose-dependent manner in AP. We also found that Drug D alleviated TXNIP up-regulation and oxidative stress in AP. Moreover, our results revealed that GSDMD-/- mitigated AP by inhibiting TXNIP/HIF-1α. Therefore, Drug D, which is extracted from Dioscorea zingiberensis, may inhibit L-arginine-induced AP by meditating GSDMD in the ER by the TXNIP /HIF-1α pathway.

Berberine-mediated REDD1 down-regulation ameliorates senescence of retinal pigment epithelium by interrupting the ROS-DDR positive feedback loop.

BACKGROUND: Accumulation of age-associated senescent cells accompanied with increased reactive oxygen species (ROS) and inflammatory factors contributes to the progression of age-related macular degeneration (AMD), the main cause of blindness in the elderly. Berberine (BBR) has shown efficacy in the treatment of age-related diseases including diabetes and obesity by decreasing ROS. However, the pharmacological effect of BBR on alleviating retinal aging remains largely unknown. PURPOSE: Our study aimed to investigate the pharmacological effect of BBR as an anti-aging agent in retinal aging and its further molecular mechanisms. METHODS: D-galactose (DG)-induced ARPE-19 cell senescence and retinal aging were employed to evaluate the anti-aging effect of BBR in vivo and in vitro. The siRNA transfection, Western-Blot analyses, SA-ß-Gal assay and immunofluorescence were performed to investigate the potential mechanisms of BBR on anti-aging of RPE. RESULTS: In RPE-choroid of both natural aged and DG-induced accelerated aged mice, oxidative stress was increased along with the up-regulation of p21 expression, which was ameliorated by BBR treatment. BBR down-regulated the expression of REDD1 to decrease intracellular ROS content, attenuating DG-induced senescence in vitro and in vivo. Furthermore, p53 instead of HIF-1α was identified as the transcriptional regulator of REDD1 in DG-induced premature senescence. Importantly, NAC and BBR reversed the expression of p53 and the content of 8-OHdG, indicating that the positive feedback loop of ROS-DNA damage response (DDR) was formed, and BBR interrupted this feedback loop to alleviate DG-induced premature senescence by reducing REDD1 expression. In addition, BBR restored DG-damaged autophagy flux by up-regulating TFEB-mediated lysosomal biosynthesis by inhibiting REDD1 expression, thereby attenuating cellular senescence. CONCLUSION: BBR down-regulates REDD1 expression to interrupt the ROS-DDR positive feedback loop and restore autophagic flux, thereby reducing premature senescence of RPE. Our findings elucidate the promising effects of REDD1 on cellular senescence and the great potential of BBR as a therapeutic approach.

A selective, sensitive, and chromogenic chemodosimeter for cyanide based on the 1,1'-binaphthyl scaffold.

A highly selective chemodosimeter 1 for cyanide based on the 1,1'-binaphthyl skeleton is described which demonstrated significant visual change and a low limit of detection. Interestingly, a reversible process triggered successively by CN(-) and Au(3+) is also observed and determined by fluorescence, UV-vis spectra, (1)H NMR titration, and ESI-MS.

Vitamin B12 Attenuates Acute Pancreatitis by Suppressing Oxidative Stress and Improving Mitochondria Dysfunction via CBS/SIRT1 Pathway.

Acute pancreatitis is an inflammatory disorder of the pancreas associated with substantial morbidity and mortality, which is characterized by a rapid depletion of glutathione (GSH). Cysthionine-ß-synthase (CBS) is a key coenzyme in GSH synthesis, and its deficiency is related to a variety of clinical diseases. However, whether CBS is involved in the pathogenesis of acute pancreatitis remains unclear. First, we found that CBS was downregulated in both in vivo and in vitro AP models. The pancreatic damage and acinar cell necrosis related to CBS deficiency were significantly improved by VB 12, which stimulated clearance of reactive oxygen species (ROS) by conserving GSH. Furthermore, EX-527 (a specific inhibitor of SIRT1) exposure counteracted the protective effect of VB 12 by promoting oxidative stress and aggravating mitochondrial damage without influencing CBS, indicating that vitamin B12 regulates SIRT1 to improve pancreatical damage by activating CBS. In conclusion, we found that VB 12 protected acute pancreatitis associated with oxidative stress via CBS/SIRT1 pathway.

Reduction-triggered di-block copolymer prodrug for high-performance long-acting tumor-selective killing.

Long-acting drug delivery systems (DDSs) have attracted interests for tumor chemotherapy. Here, novel reduction-triggered polymer prodrug was designed by conjugation of a high-performance thiolated doxorubicin (DOX-SH) onto the diblock copolymer PEG43-PPDSM43via the bioreducible cleavable disulfide bond. The resultant polymer prodrug PEG43-PPDSM43-DOX with a DOX content of 33 % could be easily self-assembled into nanoparticles of 146 nm. They showed a slow solubility-controlled sustained drug release with a cumulative release of 30.13 % within 84 h in the simulated tumor intracellular microenvironment but an ultra-low premature drug leakage of 4.01 % in the simulated normal physiological media. Such slow sustained release is expected to prolong the action time of the active drug. The MTT assays demonstrated the tumor-selective killing performance of the proposed prodrug nanoparticles with an enhanced antitumor efficacy on the tumor HepG2 cells than the free DOX, but no obvious cytotoxicity on the normal L20 cells at the lower dosages.

Improving drug delivery performance of pH-triggered prodrug nanoparticles with an adaptive polycation block as pH-sensitive gatekeeper.

Efficient approach was established to improve the drug delivery performance of the pH-triggered prodrug nanoparticles by introducing a polycation block as a pH-sensitive gatekeeper. With the help of the poly(2-(diisopropylamino)ethyl methacrylate) (PDPA) block as a pH-sensitive shell gatekeeper, the proposed core-shell-corona PEG43-b-PDPA65-b-PFPMA36-DOX nanoparticles possessed a higher drug release rate in the simulated acidic tumor intracellular micro-environment while a lower premature drug leakage in the simulated weak basic normal physiological medium, compared with the core-shell PEG43-b-PFPMA36-DOX nanoparticles. The proposed strategy is expected to design high-performance drug delivery systems (DDSs) for tumor treatment, with improved anticancer efficacy but minimized toxic side effects.

Absolutely "off-on" fluorescent CD-based nanotheranostics for tumor intracellular real-time imaging and pH-triggered DOX delivery.

Carbon dots (CDs) have attracted intense attention in tumor nanotheranostics recently; however, those nanotheranostics exhibited similar fluorescence in both normal and tumor tissues, limiting their practical application. In the present work, absolutely "off-on" fluorescent CD-based nanotheranostics was designed for tumor intracellular real-time imaging and pH-triggered DOX delivery via both static quenching by the crosslinking of benzaldehyde-containing diblock copolymers and dynamic quenching because of the surrounding conjugated DOX molecules. The proposed PPEGMA42-b-PFPMA122-(CDs)-DOX nanotheranostics did not exhibit fluorescence in a normal physiological medium, while strong fluorescence recovery occurred in the tumor intracellular microenvironment due to pH-triggered disintegration, releasing the CDs and DOX. The pH-triggered DOX release and absolute "off-on" fluorescence make the proposed nanotheranostics promising for tumor-specific pH-triggered DOX delivery and imaging.