pH-Controllable Redox Responsive Amphiphilic Viologens for Switchable Emulsions.

A pH and redox dual responsive amphiphilic viologen is synthesized, which can be reversibly transformed among the zwitterionic (SVa), monovalent anionic (SV+), and divalent anionic (SVH2+) forms upon pH variation, exhibiting pH-controllable redox responsive properties. Switchable Pickering emulsions with different droplet size and viscosity are prepared by the mixture of hydrophilic silica nanoparticles and the viologens (SV+ or SVH2+) at acidic conditions, while such combination yielded an oil-in-dispersion emulsion at neutral pH value. Not only can rapid reversible demulsification/stabilization of the Pickering emulsions be achieved by redox reactions, but the rate of redox-demulsification can also be controlled by pH trigger. The dual-responsive amphiphilic viologens have potential applications in developing intelligent colloid materials and molecular logic systems.

Critical Design Strategies Supporting Optimized Drug Release from Polymer-Drug Conjugates.

The importance of an adequate linking moiety design that allows controlled drug(s) release at the desired site of action is extensively studied for polymer-drug conjugates (PDCs). Redox-responsive self-immolative linkers bearing disulfide moieties (SS-SIL) represent a powerful strategy for intracellular drug delivery; however, the influence of drug structural features and linker-associated spacers on release kinetics remains relatively unexplored. The influence of drug/spacer chemical structure and the chemical group available for conjugation on drug release and the biological effect of resultant PDCs is evaluated. A "design of experiments" tool is implemented to develop a liquid chromatography-mass spectrometry method to perform the comprehensive characterization required for this systematic study. The obtained fit-for-purpose analytical protocol enables the quantification of low drug concentrations in drug release studies and the elucidation of metabolite presence. and provides the first data that clarifies how drug structural features influence the drug release from SS-SIL and demonstrates the non-universal nature of the SS-SIL. The importance of rigorous linker characterization in understanding structure-function correlations between linkers, drug chemical functionalities, and in vitro release kinetics from a rationally-designed polymer-drug nanoconjugate, a critical strategic crafting methodology that should remain under consideration when using a reductive environment as an endogenous drug release trigger.

Advancing targeted combination chemotherapy in triple negative breast cancer: nucleolin aptamer-mediated controlled drug release.

BACKGROUND: Triple-negative breast cancer (TNBC) is a recurrent, heterogeneous, and invasive form of breast cancer. The treatment of TNBC patients with paclitaxel and fluorouracil in a sequential manner has shown promising outcomes. However, it is challenging to deliver these chemotherapeutic agents sequentially to TNBC tumors. We aim to explore a precision therapy strategy for TNBC through the sequential delivery of paclitaxel and fluorouracil. METHODS: We developed a dual chemo-loaded aptamer with redox-sensitive caged paclitaxel for rapid release and non-cleavable caged fluorouracil for slow release. The binding affinity to the target protein was validated using Enzyme-linked oligonucleotide assays and Surface plasmon resonance assays. The targeting and internalization abilities into tumors were confirmed using Flow cytometry assays and Confocal microscopy assays. The inhibitory effects on TNBC progression were evaluated by pharmacological studies in vitro and in vivo. RESULTS: Various redox-responsive aptamer-paclitaxel conjugates were synthesized. Among them, AS1411-paclitaxel conjugate with a thioether linker (ASP) exhibited high anti-proliferation ability against TNBC cells, and its targeting ability was further improved through fluorouracil modification. The fluorouracil modified AS1411-paclitaxel conjugate with a thioether linker (FASP) exhibited effective targeting of TNBC cells and significantly improved the inhibitory effects on TNBC progression in vitro and in vivo. CONCLUSIONS: This study successfully developed fluorouracil-modified AS1411-paclitaxel conjugates with a thioether linker for targeted combination chemotherapy in TNBC. These conjugates demonstrated efficient recognition of TNBC cells, enabling targeted delivery and controlled release of paclitaxel and fluorouracil. This approach resulted in synergistic antitumor effects and reduced toxicity in vivo. However, challenges related to stability, immunogenicity, and scalability need to be further investigated for future translational applications.

Underwater Adhesives from Redox-Responsive Polyplexes of Thiolated Polyamide Polyelectrolytes.

We report the fabrication of optically clear underwater adhesives using polyplexes of oppositely charged partially-thiolated polyamide polyelectrolytes (TPEs). The thiol content of the constituent PEs was varied to assess its influence on the adhesive properties of the resulting glues. These catechol-free, redox-responsive TPE-adhesives were formulated in aquo and exhibited high optical transparency and strong adhesion even on submerged or moist surfaces of diverse polar substrates such as glass, aluminium, wood, and bone pieces. The adhesives could be cured under water through oxidative disulphide crosslinking of the constituent TPEs. The polyamide backbone provided multi-site H-bonding interactions with the substrates while the disulphide crosslinking provided the cohesive strength to the glue. Strong adhesion of mammalian bones (load bearing capacity upto 7 kg/cm2 ) was achieved using the adhesive containing 30 mol % thiol residues. Higher pH and use of oxidants such as povidone-iodine solution enhanced the curing rate of the adhesives, and so did the use of Tris buffer instead of Phosphate buffer. The porous architecture of the adhesive and its progressive degradation in aqueous medium over the course of three weeks bode well for diverse biomedical applications where temporary adhesion of tissues is required.

Nanoceria: an innovative strategy for cancer treatment.

Nanoceria or cerium oxide nanoparticles characterised by the co-existing of Ce3+ and Ce4+ that allows self-regenerative, redox-responsive dual-catalytic activities, have attracted interest as an innovative approach to treating cancer. Depending on surface characteristics and immediate environment, nanoceria exerts either anti- or pro-oxidative effects which regulate reactive oxygen species (ROS) levels in biological systems. Nanoceria mimics ROS-related enzymes that protect normal cells at physiological pH from oxidative stress and induce ROS production in the slightly acidic tumour microenvironment to trigger cancer cell death. Nanoceria as nanozymes also generates molecular oxygen that relieves tumour hypoxia, leading to tumour cell sensitisation to improve therapeutic outcomes of photodynamic (PDT), photothermal (PTT) and radiation (RT), targeted and chemotherapies. Nanoceria has been engineered as a nanocarrier to improve drug delivery or in combination with other drugs to produce synergistic anti-cancer effects. Despite reported preclinical successes, there are still knowledge gaps arising from the inadequate number of studies reporting findings based on physiologically relevant disease models that accurately represent the complexities of cancer. This review discusses the dual-catalytic activities of nanoceria responding to pH and oxygen tension gradient in tumour microenvironment, highlights the recent nanoceria-based platforms reported to be feasible direct and indirect anti-cancer agents with protective effects on healthy tissues, and finally addresses the challenges in clinical translation of nanoceria based therapeutics.

One-Pot Synthesis of Affordable Redox-Responsive Drug Delivery System Based on Trithiocyanuric Acid Nanoparticles.

Redox-responsive drug delivery systems present a promising avenue for drug delivery due to their ability to leverage the unique redox environment within tumor cells. In this work, we describe a facile and cost-effective one-pot synthesis method for a redox-responsive delivery system based on novel trithiocyanuric acid (TTCA) nanoparticles (NPs). We conduct a thorough investigation of the impact of various synthesis parameters on the morphology, stability, and loading capacity of these NPs. The great drug delivery potential of the system is further demonstrated in vitro and in vivo by using doxorubicin as a model drug. The developed TTCA-PEG NPs show great drug delivery efficiency with minimal toxicity on their own both in vivo and in vitro. The simplicity of this synthesis, along with the promising characteristics of TTCA-PEG NPs, paves the way for new opportunities in the further development of redox-responsive drug delivery systems based on TTCA.

Enhanced Efficacy against Drug-Resistant Tumors Enabled by Redox-Responsive Mesoporous-Silica-Nanoparticle-Supported Lipid Bilayers as Targeted Delivery Vehicles.

Multidrug resistance (MDR) is frequently induced after long-term exposure to reduce the therapeutic effect of chemotherapeutic drugs, which is always associated with the overexpression of efflux proteins, such as P-glycoprotein (P-gp). Nano-delivery technology can be used as an efficient strategy to overcome tumor MDR. In this study, mesoporous silica nanoparticles (MSNs) were synthesized and linked with a disulfide bond and then coated with lipid bilayers. The functionalized shell/core delivery systems (HT-LMSNs-SS@DOX) were developed by loading drugs inside the pores of MSNs and conjugating with D-α-tocopherol polyethylene glycol 1000 succinate (TPGS) and hyaluronic acid (HA) on the outer lipid surface. HT-LMSNs-SS and other carriers were characterized and assessed in terms of various characteristics. HT-LMSNs-SS@DOX exhibited a dual pH/reduction responsive drug release. The results also showed that modified LMSNs had good dispersity, biocompatibility, and drug-loading capacity. In vitro experiment results demonstrated that HT-LMSNs-SS were internalized by cells and mainly by clathrin-mediated endocytosis, with higher uptake efficiency than other carriers. Furthermore, HT-LMSNs-SS@DOX could effectively inhibit the expression of P-gp, increase the apoptosis ratios of MCF-7/ADR cells, and arrest cell cycle at the G0/G1 phase, with enhanced ability to induce excessive reactive oxygen species (ROS) production in cells. In tumor-bearing model mice, HT-LMSNs-SS@DOX similarly exhibited the highest inhibition activity against tumor growth, with good biosafety, among all of the treatment groups. Therefore, the nano-delivery systems developed herein achieve enhanced efficacy towards resistant tumors through targeted delivery and redox-responsive drug release, with broad application prospects.

Aggression to Biomembranes by Hydrophobic Tail Chains under the Stimulus of Reductant.

Stimulus-responsive materials hold significant promise for antitumor applications due to their variable structures and physical properties. In this paper, a series of peptides with a responsive viologen derivative, Pep-CnV (n = 1, 2, 3) were designed and synthesized. The process and mechanism of the interaction were studied and discussed. An ultraviolet-visible (UV) spectrophotometer and fluorescence spectrophotometer were used to study their redox responsiveness. Additionally, their secondary structures were measured by Circular Dichroism (CD) in the presence or absence of the reductant, Na2SO3. DPPC and DPPG liposomes were prepared to mimic normal and tumor cell membranes. The interaction between Pep-CnV and biomembranes was investigated by the measurements of surface tension and cargo leakage. Results proved Pep-CnV was more likely to interact with the DPPG liposome and destroy its biomembrane under the stimulus of the reductant. And the destruction increased with the length of the hydrophobic tail chain. Pep-CnV showed its potential as an intelligent antitumor agent.

Redox- and pH-Responsive Water-Soluble Flexible Organic Frameworks Realize Synergistic Tumor Photodynamic and Chemotherapeutic Therapy.

Water-soluble 3D polymers with inherent nanoscale pores have been shown to be ideal platforms for the inclusion and delivery of drugs and hold a great promise as biocompatible materials for diagnostic and therapeutic purposes. Herein, a low cytotoxic water-soluble flexible organic framework FOF-S6 with a hydrodynamic diameter of about 127.5 nm is synthesized through the formation of a hydrazone bond from a semirigid tetraaldehyde and a flexible biacylhydrazines which contains a disulfide bond (1:2). FOF-S6 has the ability to dissociate and release inclusion complexes in response to weakly acidic media and glutathione (GSH) overexpressed in tumor cells. More importantly, a facile strategy is developed to contain and deliver aggregation-induced emission photosensitizers (AIE PS, TBD-DQA-540) and chemotherapeutic drugs (Doxorubicin hydrochloride, DOX). DOX-PS@FOF-S6 is synthesized by a one-pot method, which can realize efficient photo-chemotherapy under the guidance of fluorescence imaging, thereby improving the multidrug resistance of tumor cells and the instability of photosensitizers, so as to improve the tumor treatment efficacy.

Development of Surface Chemical Strategies for Synthesizing Redox-Responsive Diatomite Nanoparticles as a Green Platform for On-Demand Intracellular Release of an Antisense Peptide Nucleic Acid Anticancer Agent.

Redox-responsive silica drug delivery systems are synthesized by aeco-friendly diatomite source to achieve on-demand release of peptide nucleic acid (PNA) in tumor reducing microenvironment, aiming to inhibit the immune checkpoint programmed cell death 1 receptor/programmed cell death receptor ligand 1 (PD-1/PD-L1) in cancer cells. The nanoparticles (NPs) are coated with polyethylene glycol chains as gatekeepers to improve their physicochemical properties and control drug release through the cleavable disulfide bonds (S-S) in a reductive environment. This study describes different chemical conditions to achieve the highest NPs' surface functionalization yield, exploring both multistep and one-pot chemical functionalization strategies. The best formulation is used for covalent PNA conjugation via the S-S bond reaching a loading degree of 306 ± 25 µg PNA mg-1 DNPs . These systems are used for in vitro studies to evaluate the kinetic release, biocompatibility, cellular uptake, and activity on different cancer cells expressing high levels of PD-L1. The obtained results prove the safety of the NPs up to 200 µg mL-1 and their advantage for controlling and enhancing the PNA intracellular release as well as antitumor activity. Moreover, the downregulation of PD-L1 observed only with MDA-MB-231 cancer cells paves the way for targeted immunotherapy.

Bioreducible polyethylenimine core-shell nanostructures as efficient and non-toxic gene and drug delivery vectors.

Low molecular weight branched polyethylenimine (LMW bPEIs 1.8 kDa) have received considerable attention for the fabrication of nucleic acid carriers due to their biocompatible and non-toxic nature. However, due to the inadequate nucleic acid complexation ability and transportation across the cell membrane, these show poor transfection efficacy, limiting their clinical applications. Therefore, to overcome these challenges, in this study, we have grafted bPEI 1.8 kDa with a disulfide bond containing hydrophobic moiety, 3-(2-pyridyldithio) propionic acid (PDPA), via amide linkages through EDC/NHS-mediated coupling to obtain N-[3-(2-pyridyldithio)] propionoyl polyethylenimine (PDPP) conjugates. The best formulation for nucleic acid transfection was evaluated after preparing a series of PDPP conjugates by varying the amount of PDPA. In an aqueous environment, these PDPP conjugates self-assembled to form spherical shaped core-shell PDPP nanostructures with size ranging from âˆ¼188-307 nm and zeta-potential from ∼ +3 to +19 mV. The positively charged surface of the core-shell nanocomposites helps in the binding of plasmid DNA (pDNA), its transportation inside the cell, and protection against enzymes. Evaluation of PDPP/pDNA complexes on mammalian cells revealed that all these complexes showed significantly improved transfection efficacy without hampering cytocompatibility. Amongst all, the pDNA complex of PDPP-2 exhibited the best transfection efficiency (i.e. >6-fold) in comparison to pDNA complex of the native bPEI. The nanocomposites exhibited the redox responsive behavior advantageous for therapeutic delivery to the tumor cells. The core of the nanostructures facilitate the encapsulation of a hydrophobic model drug, ornidazole. In vitro drug release analysis showed a faster release rate in response to a reductant mimicking the cellular environment. Altogether, these nanostructures have great potential to co-deliver both drug and gene simultaneously in response to tumor cell reductive microenvironment in vitro and could be used as the next-generation delivery system.

Ultrahigh Sensitive and Tumor-Specific Photoacoustography in NIR-II Region: Optical Writing and Redox-Responsive Graphic Fixing by AgBr@PLGA Nanocrystals.

The highly up-regulated glutathione (GSH) concentration in the tumor microenvironment is generally identified to be an effective endogenous characteristic of cancerous tissues. Herein, an ultrahigh-sensitive and tumor-specific photoacoustography technique in the near-infrared (NIR-II) region based on optical writing and redox-responsive chromogenic graphic fixing is developed by introducing a self-synthesized photosensitive silver bromide modified with poly lactic-co-glycolic acid (AgBr@PLGA) nanocrystals. After they are optically triggered by external light, the NIR-transparent AgBr@PLGA nanocrystals can be reduced by the tumor-abundant GSH into strongly absorbing silver nanoparticles, significantly boosting the "turn-on" photoacoustic (PA) signal in the NIR-II region; therefore, the tumor area can be graphically fixed and developed in the photoacoustography. Experiments on both in vitro phantoms and in vivo mouse models demonstrate that the tumor area is specifically identified by the photoacoustography with the background signals effectively suppressed by dynamically modulating the exposure time. The tumor-specific photoacoustography technique prefigures great potential for high-precision cancer diagnosis and treatment monitoring.

Far-Red Light Coordinates the Diurnal Changes in the Transcripts Related to Nitrate Reduction, Glutathione Metabolism and Antioxidant Enzymes in Barley.

Spectral quality, intensity and period of light modify many regulatory and stress signaling pathways in plants. Both nitrate and sulfate assimilations must be synchronized with photosynthesis, which ensures energy and reductants for these pathways. However, photosynthesis is also a source of reactive oxygen species, whose levels are controlled by glutathione and other antioxidants. In this study, we investigated the effect of supplemental far-red (735 nm) and blue (450 nm) lights on the diurnal expression of the genes related to photoreceptors, the circadian clock, nitrate reduction, glutathione metabolism and various antioxidants in barley. The maximum expression of the investigated four photoreceptor and three clock-associated genes during the light period was followed by the peaking of the transcripts of the three redox-responsive transcription factors during the dark phase, while most of the nitrate and sulfate reduction, glutathione metabolism and antioxidant-enzyme-related genes exhibited high expression during light exposure in plants grown in light/dark cycles for two days. These oscillations changed or disappeared in constant white light during the subsequent two days. Supplemental far-red light induced the activation of most of the studied genes, while supplemental blue light did not affect or inhibited them during light/dark cycles. However, in constant light, several genes exhibited greater expression in blue light than in white and far-red lights. Based on a correlation analysis of the gene expression data, we propose a major role of far-red light in the coordinated transcriptional adjustment of nitrate reduction, glutathione metabolism and antioxidant enzymes to changes of the light spectrum.

Stimuli-Responsive Polypeptide Nanoparticles for Enhanced DNA Delivery.

The development of non-viral delivery systems for effective gene therapy is one of the current challenges in modern biomedicinal chemistry. In this paper, the synthesis of pH- and redox-responsive amphiphilic polypeptides for intracellular DNA delivery is reported and discussed. Two series of polypeptides consisting of L-lysine, L-phenylalanine, L-histidine, and L-cysteine as well as the same amino acids with L-glutamic acid were synthesized by a combination of copolymerization of N-carboxyanhydrides of α-amino acids and post-polymerization modification of the resulting copolymers. The presence of histidine provided pH-sensitive properties under weakly acidic conditions specific to endosomal pH. In turn, the presence of cysteine allowed for the formation of redox-responsive disulfide bonds, which stabilized the self-assembled nanoparticles in the extracellular environment but could degrade inside the cell. The formation of intraparticle disulfide bonds resulted in their compactization from 200-250 to 55-100 nm. Empty and pDNA-loaded cross-linked nanoparticles showed enhanced stability in various media compared to non-crosslinked nanoparticles. At the same time, the addition of glutathione promoted particle degradation and nucleic acid release. The delivery systems were able to retain their size and surface charge at polypeptide/pDNA ratios of 10 or higher. GFP expression in HEK 293 was induced by the delivery of pEGFP-N3 with the developed polypeptide nanoparticles. The maximal transfection efficacy (70%) was observed when the polypeptide/pDNA ratio was 100.

Construction and Biological Evaluation of Multiple Modification Hollow Mesoporous Silicone Doxorubicin Nanodrug Delivery System.

The combination of functionalized nanoparticles and chemotherapy drugs can effectively target tumor tissue, which can improve efficacy and reduce toxicity. In this article, pPeptide-PDA@HMONs-DOX nanoparticles (phosphopeptide-modified polydopamine encapsulates doxorubicin-loaded hollow mesoporous organosilica nanoparticles) were constructed that based on multiple modification hollow mesoporous organosilica nanoparticles (HMONs). The pPeptide-PDA@HMONs-DOX nanoparticles retain the biological functions of phosphorylated peptide while exhibiting biological safety that are suitable for effective drug delivery and stimulus responsive release. The degradation behaviors showed that pPeptide-PDA@HMONs-DOX has dual-responsive to drug release characteristics of pH and glutathione (GSH). In addition, the prepared pPeptide-PDA@HMONs-DOX nanoparticles have good biological safety, and their anti-tumor efficacy was significantly better than doxorubicin (DOX). This provided new research ideas for the construction of targeted nanodrug delivery systems based on mesoporous silicon. Scheme 1 The preparation of pPeptide-PDA@HMONs-DOX and the process of drug release under multiple responses. (A) Schematic diagram of the synthesis process of pPeptide-PDA@HMONs-DOX. (B) The process in which nanoparticles enter the cell and decompose and release DOX in response to pH and GSH.

Glycol Chitosan Functionalized with a Gd(III) Chelate as a Redox-responsive Magnetic Resonance Imaging Probe to Label Cell Embedding Alginate Capsules.

One possibility for the non-invasive imaging of encapsulated cell grafts is to label the lumen of cell embedding capsules with a redox-responsive probe, as an increased extracellular reducing potential can be considered as a marker of hypoxia-induced necrosis. A Gd(III)-HPDO3A-like chelate has been conjugated to glycol-chitosan through a redox-responsive disulphide bond to obtain a contrast agent for Magnetic Resonance Imaging (MRI). Such a compound can be interspersed with fibroblasts within the lumen of alginate-chitosan capsules. Increasing reducing conditions within the extracellular microenvironment lead to the reductive cleavage of the disulphide bond and to the release of gadolinium in the form of a low molecular weight, non-ionic chelate. The efflux of such chelate from capsules is readily detected by a decrease of contrast enhancement in T1 -weighted MR images.

Polyglycerol-Based Mucus-Inspired Hydrogels.

The mucus layer is a hydrogel network that covers mucosal surfaces of the human body. Mucus has important protective properties that are related to its unique rheological properties, which are based on mucins being the main glycoprotein constituents. Mucin macromolecules entangle with one another and form a physical network that is instrumental for many important defense functions. Mucus derived from various human or animal sources is poorly defined and thus not suitable for many application purposes. Herein, a synthetic route is fabricated to afford a library of compositionally defined mucus-inspired hydrogels (MIHs). MIHs are synthesized by thiol oxidation to render disulfide bonds between the crosslinker ethoxylated trimethylolpropane tri(3-mercaptopropionate) (THIOCURE ETTMP 1300) and the linear precursors, dithiolated linear polyglycerol (LPG(SH)2 ) or polyethylene glycol (PEG(SH)2 ) of different molecular weights. The mixing ratio of linear polymers versus crosslinker and the length of the linear polymer are varied, thus delivering a library of compositionally defined mucin-inspired constructs. Their viscoelastic properties are determined by frequency sweeps at 25 and 37 °C and compared to the corresponding behavior of native human mucus. Here, MIHs composed of a 10:1 ratio of LPG(SH)2 and ETTMP 1300 are proved to be the best comparable to human airway mucus rheology.

pH-activated, mitochondria-targeted, and redox-responsive delivery of paclitaxel nanomicelles to overcome drug resistance and suppress metastasis in lung cancer.

BACKGROUND: Mitochondria play a role in the occurrence, development, drug resistance, metastasis, and other functions of cancer and thus are a drug target. An acid-activated mitochondria-targeting drug nanocarrier with redox-responsive function was constructed in the present study. However, whether this vector can precisely delivery paclitaxel (PTX) to enhance therapeutic efficacy in drug-resistant lung cancer is unknown. RESULTS: Acid-cleavable dimethylmaleic anhydride (DA) was used to modify pluronic P85-conjugated mitochondria-targeting triphenylphosphonium (TPP) using disulfide bonds as intermediate linkers (DA-P85-SS-TPP and DA-P-SS-T). The constructed nanocarriers demonstrated enhanced cellular uptake and selective mitochondrial targeting at extracellular pH characteristic for a tumor (6.5) and were characterized by extended circulation in the blood. TPP promoted the targeting of the DA-P-SS-T/PTX nanomicelles to the mitochondrial outer membrane to decrease the membrane potential and ATP level, resulting in inhibition of P-glycoprotein and suppression of drug resistance and cancer metastasis. PTX was also rapidly released in the presence of high glutathione (GSH) levels and directly diffused into the mitochondria, resulting in apoptosis of drug-resistant lung cancer cells. CONCLUSIONS: These promising results indicated that acid-activated mitochondria-targeting and redox-responsive nanomicelles potentially represent a significant advancement in cancer treatment. GRAPHIC ABSTARCT.

A redox-responsive dihydroartemisinin dimeric nanoprodrug for enhanced antitumor activity.

Redox-responsive drug delivery system emerges as a hopeful platform for tumor treatment. Dihydroartemisinin (DHA) has been investigated as an innovative tumor therapeutic agent. Herein, a DHA dimeric prodrug bridged with disulfide bond as linker (DHA2-SS) has been designed and synthesized. The prepared prodrugs could self-assemble into nanoparticles (SS NPs) with high DHA content (> 90%) and robust stability. These SS NPs display sensitive redox responsive capability and can release DHA under the tumor heterogeneity microenvironment. SS NPs possess preferable antitumor therapeutic activity in contrast with free DHA. Moreover, the possible anti-cancer mechanism of SS NPs was investigated through RNA-seq analysis, bioinformatics and molecular biological method. SS NPs could induce apoptosis via mitochondrial apoptosis pathway, as well as glycolysis inhibition associate with the regulation of PI3K/AKT/HIF-1α signal path, which may offer an underlying therapeutic target for liver cancer. Our study highlights the potential of using redox responsive prodrug nanoparticles to treat cancer, meanwhile provides insights into the anti-cancer mechanism of DHA prodrug.

Lysosome-targetable selenium-doped carbon nanodots for in situ scavenging free radicals in living cells and mice.

Lysosome-targetable selenium-doped carbon nanodots (Lyso-Se-CDs) that can efficiently scavenge lysosomal •OH in living cells and mice were designed in this research. Se-CDs with redox-responsive fluorescence (λex = 379 nm, λem = 471 nm, quantum yield = 7.1%) were initially synthesized from selenocystine by a facile hydrothermal method, followed by the surface modification with morpholine, a lysosome targeting moiety. The as-synthesized Lyso-Se-CDs exhibited excellent colloidal stability, efficient scavenging abilities towards •OH, low biotoxicity, as well as good biocompatibility and lysosome targetability. Due to these desirable properties, Lyso-Se-CDs had been successfully utilized for rescuing cells from elevated lysosomal •OH levels. More importantly, Lyso-Se-CDs efficiently relieved phorbol 12-myristate 13-acetate (PMA) triggered ear inflammation in live mice. These findings reveal that Lyso-Se-CDs are potent candidates for treating •OH-related inflammation.