Tumor-overexpressed enzyme responsive amphiphiles small molecular self-assembly nano-prodrug for the chemo-phototherapy against non-small-cell lung cancer.

Rational design of self-assembly drug amphiphiles can provide a promising strategy for constructing nano-prodrug with high drug loading, smart stimuli-responsive drug release and high tumor selectivity. Herein, we report a small molecular amphiphile prodrug that can self-assemble into multifunctional nano-prodrug for enhanced anticancer effect by the combination of chemotherapy and phototherapy (PDT/PTT). In this prodrug, the simple insertion of quinone propionate into hydrophilic drug Irinotecan (Ir) generates suitable amphiphiles that endow a good self-assembly behavior of the prodrug and transform it into a stable and uniform nanoparticle. Interestingly, this excellent self-assembly behavior can load phototherapy agent ICG to form a multifunctional nano-prodrug, thereby enhancing the chemotherapeutic effect with PDT/PTT. Importantly, the quinone propionic acid moiety in the prodrug showed a high sensitivity to the overexpressed NAD(P)H:quinone oxidoreductase-1 (NQO1) in non-small cell lung cancer (NSCLC) cells, and this sensitivity enables the disassembly of nano-prodrug and efficient NQO1-responsive drug release. To further enhance the drug accumulation on tumor tissue and migrate the blood clearance, a biomimetic nano-prodrug has been successfully explored by coating hybrid membrane on the above nano-prodrug, which displays high selective inhibition of tumor growth and metastasis on NSCLC mice model. Our findings provide new insights into the rational design of tumor-overexpressed enzyme responsive nano-prodrug for cancer combinational therapy.

Rational N,P-Codoped pH-Activatable Red Carbon Dot for In Vitro and In Vivo Tumor Imaging.

Tumor detection and imaging via tumor microenvironmental indicators can have practical value. Here, a low-pH-responsive red carbon dot (CD) was prepared via a hydrothermal reaction for specific tumor imaging in vitro and in vivo. The probe responded to the acidic tumor microenvironment. The CDs are codoped by nitrogen and phosphorene and contain anilines on the surface. These anilines are efficient electron donors and modulate the pH response: Fluorescence is undetectable at common physical pH (>7.0), but red fluorescence (600-720 nm) increases with decreasing pH. The inactivation of fluorescence is due to three aspects: photoinduced electron transfer from anilines, deprotonation-induced energy states changing, and particle aggregation-induced quenching. It is believed that this pH-responsive character of CD is better than other reported CDs. Thus, in vitro images of HeLa cells show strong fluorescence that is 4-fold higher than normal cells. Subsequently, the CDs are used for in vivo imaging of tumors in mice. Tumors can be clearly observed within 1 h, and clearance of CDs will be finished within 24 h due to the small size of the CDs. The CDs offer excellent tumor-to-normal tissue (T/N) ratios and have great potential for biomedical research and disease diagnosis.

A self-assembly nano-prodrug for triple-negative breast cancer combined treatment by ferroptosis therapy and chemotherapy.

Chemotherapeutics have been recommended as the standard protocol for inoperable patients with triple-negative breast cancer (TNBC) at advanced stage, yet limited success has been achieved in prolonging survival rates by this monotherapy. A major reason for this failure is the chemo-resistance from traditional apoptotic pathways resulting in poor therapeutic effect. Ferroptosis has become a powerful modality of no-apoptotic cell death, which can effectively evade chemo-resistance in apoptotic pathways. Herein, we propose an active-targeting small-molecular self-assembly nano-prodrug for co-delivery of chemotherapeutics (CPT), Ferrocene (Fc) and GPX4 inhibitor (RSL3) to overcome the chemo-resistance from traditional apoptotic pathways. In this nano-prodrug, the disulfide linkage not only serves as a GSH-responsive trigger, but also exhibits a stable self-assembly behavior that forms nanoparticle. Interestingly, the RSL3 can be loaded during this self-assembly process that forms a three-components nano-prodrug. In tumor environment, the high GSH level can disassemble the nano-prodrug to trigger the release of the parent drug, which can improve the therapeutic effect by synergistic effects of ferroptosis and apoptosis. In different TNBC mice models, the nano-prodrug is encapsulated into RGD-modified phospholipid micelles (DSPE-PEG2000-RGD) and exhibits high anti-tumor and anti-metastasis efficacy, especially in orthotopic models. The application of ferroptosis to assist the enhancement of chemotherapeutics may serve as a promising strategy for TNBC treatment. STATEMENT OF SIGNIFICANCE: Chemotherapeutics have been recommended as the standard of care for palliative and adjuvant treatment in patients with triple-negative breast cancer (TNBC), yet limited success has been achieved in prolonging the overall survival of patients by this monotherapy. A major reason for this failure is the chemo-resistance from traditional apoptotic pathways resulting in poor therapeutic effect. Thus, the co-delivery of the apoptosis and ferroptosis drug may overcome or evade the resistance in chemotherapy-induced apoptotic pathways and provide a promising strategy to combat TNBC. In this work, we developed a small-molecular self-assembly nano-prodrug for co-delivery of chemotherapeutics (CPT), Ferrocene (Fc) and ferroptosis resistance inhibitor (RSL3), which could overcome the chemo-resistance and improve the therapeutic effect by synergistic effects of ferroptosis and apoptosis.

A novel dual-channel fluorescent probe for selectively and sensitively imaging endogenous nitric oxide in living cells and zebrafish.

Nitric oxide (NO) plays various physiological and pathological roles in lots of biological processes. It is crucial to detect NO sensitively and selectively in vivo and in vitro as homeostasis of NO is closely related to various diseases. Herein, a novel dual-channel fluorescent dye (ENNH2) based on dicarboxyimide anthracene was developed as a highly sensitive and selective probe to detect NO in living systems using the dual-channel fluorescence. ENNH2 can emit bright red fluorescence due to the intramolecular charge transfer (ICT) from the amino group at the 6-position of 1,2-dicarboxyimide anthracene to the conjugated aromatic ring, and the ICT is effectively inhibited by the reductive deamination of the amino in the presence of NO to obtain the remarkable strong green emission with the excellent sensitivity (5.52 nM). Promisingly, ENNH2 exhibits an excellent performance in endogenous NO dual-channel fluorescence imaging of RAW 264.7 cells and zebrafish.

A biomimetic nanodrug self-assembled from small molecules for enhanced ferroptosis therapy.

Ferroptosis drugs often induce oxidative damage or block antioxidant defense due to the key mechanism of ferroptosis involved in cancer treatment, regulating the intracellular redox balance. However, these ferroptosis drugs are unstable during systemic circulation, and they lack tumor-targeting capability. Herein, we developed a stimuli-responsive and cell membrane-coated nanodrug for the simultaneous delivery of two ferroptosis drugs, an iron-chelating drug as a ROS inducer and sorafenib as an antioxidase inhibitor. The coating of the cancer cell membrane over the nanodrug can enhance the tumor-targeting capability and improve the stability in the blood circulation. In addition, the nanodrug exhibits sensitive drug release profiles in response to glutathione (GSH) and reactive oxygen species (ROS) in tumor microenvironments due to the dynamic diselenide bonds. The released iron-chelating drug and sorafenib not only produce hydroxyl radicals (˙OH) to induce ferroptosis, but also inhibit the expression of GPX4 to mitigate the ferroptosis resistance. Excitingly, the systemic administration of this biomimetic nanodrug displays superior antitumor and anti-metastatic effects in tumor-bearing mice. Our findings provide a promising therapeutic strategy for the co-delivery of ferroptosis inducers and antioxidase inhibitors to strengthen the therapeutic efficacy of ferroptosis.

A metal-organic framework/aptamer system as a fluorescent biosensor for determination of aflatoxin B1 in food samples.

The demand of simple, sensitive, selective and reliable assay for aflatoxin B1 (AFB1) detection is ubiquitous in food safety, due to its high toxic. Herein, a novel fluorescent aptasensor using metal-organic frameworks (UiO-66-NH2) and TAMRA label aptamer as sensing platform for AFB1 detection was developed. The TAMRA aptamer adsorbed on the surface of UiO-66-NH2 via van der Waals force and its fluorescence was quenched for the charge transfer from fluorescence dye TAMRA to metal ions of UiO-66-NH2. After introducing AFB1 to the system, the TAMRA aptamer binded to AFB1 and formed TAMRA aptamer/AFB1complex, making its conformation change and resulting in fluorescence recovery. Thus, the quantity of AFB1 could be analyzed according to the fluorescence signal change. Under optimize experimental conditions, the assay exhibited high sensitivity toward AFB1 in range of 0-180 ng mL-1 with low limit of detection of 0.35 ng mL-1 and good specificity against other toxins. Moreover, the aptamer/metal-organic frameworks sensing platform could be utilized to determine AFB1 content in food samples such as corn, rice and milk. It provided a reasonable method for other mycotoxin detection by changing the sequence of aptamer.

Nitrogen-sulfur co-doped pH-insensitive fluorescent carbon dots for high sensitive and selective hypochlorite detection.

Carbon dots (CDs) are novel fluorescent carbon nanomaterial with exceptional properties and have drawn great attention in recent years. However, the preparation and applications of high-quality carbon dots remain challenging. Here, we describe a simple hydrothermal synthesis route using citric acid as a carbon source for stable fluorescent CDs. The CDs are modified with glutathione and exhibit high fluorescent quantum yields (30.2%) and excellent photo-stability. In addition, the fluorescence intensity of CDs remains stable over a wide range of pH values (3-12). Hypochlorite (ClO-) can effectively quench the fluorescence of the CDs by destroying the pyrrolic ring and conjugate structure of the CDs. Thus, the CDs can be used to detect ClO-. Under optimized conditions, the fluorescence intensity changes of CDs correspond selectively to ClO- in the range of 100-800 nmol/L with a LOD of 16 nmol/L. Practical applications of the proposed method for free chlorine detection in tap water show similar results and recovery compared to the standard DPD-based method. These results suggest that the pH-insensitive CDs prepared via this facile procedure are a promising chemosensor for free chlorine and have great potential in analytical applications.

Synthesis of the cationic fluorescent probes for the detection of anionic surfactants by electrostatic self-assembly.

Anionic surfactants were widespread used in car cleaning agents, household detergents, agricultural and industrial processes, and considered as a major source of environmental pollutant. Therefore, it is necessary to develop a fast, simple, highly selective and sensitive probe for the detection of anionic surfactants. Here, we synthesized two aggregation induced emission (AIE)-active molecules 4,4',4″,4‴-(ethene-1,1,2,2-tetrayltetrakis(benzene-4,1-diyl))tetrakis (1-(4-bromobenzyl)pyridin-1-ium) bromide (TPE-Br) and 4,4',4″,4‴-(ethene-1,1,2,2-trayltetrakis(benzene-4,1-diyl))tetrakis(1-methylpyridin-1-ium)iodide (TPE-I), which were then applied as fluorescence probes for detecting sodium dodecyl sulfate (SDS) with high selectivity and sensitivity. In the presence of SDS, a multi-fold fluorescence emission intensity enhancement was observed in both two probes (TPE-Br and TPE-I) due to the electrostatic self-assembly of AIE molecular. The limits of detection are 71.5 and 120 nM for TPE-Br and TPE-I, respectively. This study may provide a new strategy for environmental monitoring by AIE-based fluorescent probe.

One Step Preparation of Peptide-Coated Gold Nanoparticles with Tunable Size.

Gold nanoparticles (AuNPs) made from self-assembling peptides have been used in many research fields and attracted a great deal of attention due to their high stability, biocompatibility and functionality. However, existing preparation methods for peptide-coated AuNPs are post-synthesis processes, which are complicated and time consuming. Therefore, a one-step preparation method for peptide-coated AuNPs is proposed here. The AuNPs obtained by this method exhibit good stability. Importantly, peptide-coated AuNPs with precise different sizes can be prepared by this method through pH control of reducing reagent tyrosine in range of 10.0~12.7. Thus, the one-step preparation method proposed here provides a significant tool for the research in different fields concerning NP size, stability and biocompatibility.

1,6-Elimination reaction induced detection of fluoride ions in vitro and in vivo based on a NIR fluorescent probe.

Near-Infrared "turn on" type fluorescent probes are attractive and promising in the fields of chemical sensing and bioimaging. Here, a new dicyanomethylene-4H-pyran derivative (DCM-Si) NIR fluorescent probe was designed and synthesized for specific lighting up F- in living cells and bodies. SiO bond was used as F- trigger, and the release of fluorophore (DCM-NH2) occurred after substituent reaction and subsequent 1,6-elimination. This NIR probe displayed high sensitivity and selectivity for the sensing of F-, and the detection limit was calculated to be as low as 157 nM. Moreover, the "off-on" fluorescent signal changes can be realized by adding F- in living cells and zebrafish embryos.

A label-free fluorescent aptasensor for the detection of Aflatoxin B1 in food samples using AIEgens and graphene oxide.

The detection of Aflatoxin B1 (AFB1) has attracted extensive attention for food safety is a worldwide public health problem. Herein, a novel, simple and label-free fluorescent aptasensor, based on quaternized tetraphenylethene salt (TPE-Z), graphene oxide (GO) and AFB1 aptamer, has been constructed to detect AFB1. In the presence of AFB1, AFB1 aptamer undergoes a conformational switch from single stranded structure to the AFB1/AFB1 aptamer complex upon target binding, which induces the release of TPE-Z/AFB1 aptamer from the surface of GO. Thus, the fluorescence of TPE-Z/AFB1 aptamer is recovered. The assay can be performed by simply mixing TPE-Z, AFB1 aptamer, the GO and the AFB1 samples with a detection limit of 0.25 ng/mL. It is highly selective against other aflatoxins in foods and its performance has been verified in food samples (corn, milk and rice) with known concentration AFB1.

A self-immolative prodrug nanosystem capable of releasing a drug and a NIR reporter for in vivo imaging and therapy.

In vivo monitoring of the biodistribution and activation of prodrugs is highly attractive, and the self-immolative dendritic architecture is deemed as a promising approach for constructing theranostic prodrug in which the release/activation of different payloads is needed. Herein, A GSH-triggered and self-immolative dendritic platform comprising an anticancer drug camptothecin (CPT), a cleavable linker and a two-photon NIR fluorophore (dicyanomethylene-4H-pyran, DCM) has been developed for in situ tracking of drug release and antitumour therapy. In vitro experiments demonstrate that, the presence of glutathione (GSH) induces the cleavage of the self-immolative linker, resulting in comitant release of the drug and the dye. Upon cell internalization and under one- or two-photon excitation, prominent intracellular fluorescence can be observed, indicating the release of the payloads in live cells. Upon loaded in phospholipid vesicles, the prodrug has also been successfully utilized for in vivo and in situ tracking of drug release and cancer therapy in a mouse model. Several hours post injection, the prodrug generates strong fluorescence on tumour sites, demonstrating the prodrug's capability of monitoring the on-site drug release. Moreover, the prodrug shows considerable high activity and exerts obvious inhibition towards tumour growth. This work suggests that the prodrug with self-immolative dendritic structure can work well in vivo and this strategy may provide an alternative approach for designing theranostic drug delivery systems.

A bioorthogonal nanosystem for imaging and in vivo tumor inhibition.

Bioorthogonal bond-cleavage reactions have emerged as promising tools for manipulating biological processes, still the therapeutic effect of these reactions in vivo needs to be explored. Herein a bioorthogonal-activated prodrug has been developed for bioimaging and therapy, which is composed of a Pd-mediated cleavable propargyl, a coumarin fluorophore and a potent anticancer drug. In vitro investigations show that, the presence of a Pd complex induces the cleavage of propargyl and subsequently trigger the cascade of reactions, thereby activating the coumarin fluorophore for imaging and releasing the anticancer drug for therapy. Both the prodrug and Pd complex were then separately encapsulated into phospholipid liposomes to form a two-component bioorthogonal nanosystem. The lyposomal nanosystem can be readily internalized by HeLa cells and displays strong intracellular fluorescence under one- or two-photon excitation, indicating the release of the active drug in cells as a result of the Pd-mediated bioorthogonal bond-cleavage reaction. More importantly, the nanosystem shows considerable high activity and exerts efficient inhibition towards tumor growth in a mouse model. This work demonstrates that, if properly formulated, a bioorthogonal system can perform well in vivo. This strategy may offer a new approach for designing bioorthogonal prodrugs with imaging and therapeutic capability.

A self-immolative and DT-diaphorase-activatable prodrug for drug-release tracking and therapy.

DT-diaphorase, which catalyzes the reduction of various biological substances like quinones, is overexpressed in some malignant tumors. However, exploiting this attractive property for the controlled release of an active drug from a prodrug is yet to be fully taken advantage of. Herein we report a DT-diaphorase-based prodrug for concomitant drug-release imaging and cancer chemotherapy. This prodrug system is composed of two camptothecin (CPT) moieties as the active anticancer drug, a DT-diaphorase-responsive quinone propionic acid moiety and a set of self-immolative linkers. The presence of DT-diaphorase leads to the release of two CPT molecules and restores the fluorescence of the latter, thereby realizing the fluorescence monitoring of the DT-diaphorase level as well as the tracking of CPT release. Upon internalization by DT-diaphorase overexpressing cells, the prodrug can release fluorescent CPT and exhibit high cytotoxicity (half-maximal inhibitory concentration 0.71 µM) towards the cancer cells. This prodrug features on-demand enzyme-biomarker-triggered drug release as well as self-monitoring of drug release, therapeutic effect and biomarker level. This new strategy may provide an effective approach for constructing prodrugs with enhanced drug loading as well as controllability for drug release and tracking.

A two-photon-activated prodrug for therapy and drug release monitoring.

A light-activated cleavage strategy for the concomitant release of active drugs and generation of fluorescence changes is highly desirable. Herein a molecular prodrug featuring real-time monitoring of drug localization and release by manipulating fluorophores has been created by constructing a cleavable structure which comprises a photoremovable coumarinyl, an anticancer drug camptothecin, a cleavable linker and a near infrared fluorescent dye dicyanomethylene-4H-pyran (DCM). The fluorescence of coumarinyl and CPT is completely quenched by the DCM moiety via fluorescence resonance energy transfer (FRET). The internalization of the prodrug by cells and its subsequent intracellular location can be tracked by collecting the red fluorescence of DCM; while the release of active CPT as a result of one- or two-photon irradiation can be monitored by observing the newly emerged fluorescence of CPT under one- or two-photon excitation. The prodrug also shows highly controllable cytotoxicity toward HeLa cells and A549 cells, with low IC50 values of 4.01 and 2.53 µM, respectively, upon light irradiation and with much higher IC50 values (>40 µM) without light irradiation. This strategy may provide an approach for the development of light-activatable theranostic anticancer therapeutics.

A DT-diaphorase responsive theranostic prodrug for diagnosis, drug release monitoring and therapy.

A DT-diaphorase-activatable theranostic prodrug, which contains camptothecin, a self-immolative linker and a trigger group, has been developed for the detection of DT-diaphorase, tracking of drug release and selectively killing cancer cells over-expressed with DT-diaphorase. This strategy may offer a new approach for the development of enzyme-catalyzed theranostic anticancer therapeutics.

Poly[[tetra-aqua-µ(4)-fumarato-di-µ(3)-fumarato-dineodymium(III)] trihydrate].

The title coordination polymer, {[Nd(2)(C(4)H(2)O(4))(3)(H(2)O)(4)]·3H(2)O}, was synthesized by the reaction of neodymium(III) nitrate hexa-hydrate with fumaric acid in a water-methanol (7:3) solution. The asymmetric unit comprises two Nd(3+) cations, three fumarate dianions (L(2-)), four aqua ligands and three uncoordinated water mol-ecules. The carboxyl-ate groups of the fumarate dianions exhibit different coordination modes. In one fumarate dianion, two carboxyl-ate groups chelate two Nd(3+) cations, while one of the O atoms is coordinated to another Nd(3+) cation. Another fumarate dianion bridges three Nd(3+) cations: one of the carboxyl-ate groups chelates one Nd(3+) cation, while the other carboxyl-ate group bridges two Nd(3+) cations in a monodentate mode. The third fumarate dianion bridges four Nd(3+) cations, where one of the carboxyl-ate groups chelates one Nd(3+) cation and coordinates in a monodentate mode to a second Nd(3+), while the second carboxyl-ate groups bridges two Nd(3+) cations in a monodentate mode and one O atom is coordinated to one Nd(3+) cation. The Nd(3+) cations are in a distorted tricapped-trigonal prismatic environment and coordinated by seven O atoms from the fumarate ligands and two O atoms from water mol-ecules. The Nd(3+) cations are linked by two carboxyl-ate O atoms and two carboxyl-ate groups, generating infinite Nd-O chains to form a three-dimensional framework. There are O-H⋯O and C-H⋯O hydrogen-bonding interactions between the coordin-ated and uncoordinated water mol-ecules and carboxyl-ate O atoms.

Poly[diaquabis-(µ(4)-fumarato-κO:O:O:O)(µ(4)-fumarato-κO:O,O:O:O,O)(µ(2)-fumaric acid-κO:O)dipraseodymium(III)].

The title complex, [Pr(2)(C(4)H(2)O(4))(3)(C(4)H(4)O(4))(H(2)O)(2)](n), was synthesized by reaction of praseodymium(III) nitrate hexa-hydrate with fumaric acid in a water-ethanol (4:1) solution. The asymmetric unit comprises a Pr(3+) cation, one and a half fumarate dianions (L(2-)), one half-mol-ecule of fumaric acid (H(2)L) and one coordinated water mol-ecule. The carboxyl-ate groups of the fumarate dianion and fumaric acid exhibit different coordination modes. In one fumarate dianion, two carboxyl-ate groups are chelating with two Pr(3+) cations, and the other two O atoms each coordinate a Pr(3+) cation. Each O atom of the second fumarate dianion binds to a different Pr(3+) cation. The fumaric acid employs one O atom at each end to bridge two Pr(3+) cations. The Pr(3+) cation is coordinated in a distorted tricapped trigonal-prismatic environment by eight O atoms of fumarate dianion or fumaric acid ligands and one water O atom. The PrO(9) coordination polyhedra are edge-shared through one carboxyl-ate O atom and two carboxyl-ate groups, generating infinite praseodymium-oxygen chains, which are further connected by the ligands into a three-dimensional framework. The crystal structure is stabilized by O-H⋯O hydrogen-bond inter-actions between the coordin-ated water mol-ecule and the carboxyl-ate O atoms.

2-(3,3,4,4-Tetra-fluoro-pyrrolidin-1-yl)aniline.

In the title fluorinated pyrrolidine derivative, C(10)H(10)F(4)N(2), the dihedral angle between the best planes of the benzene and pyrrolidine rings is 62.6 (1)°. The crystal packing features inter-molecular N-H⋯F hydrogen bonds.

3,3,4,4-Tetra-fluoro-1-[2-(3,3,4,4-tetra-fluoro-pyrrolidin-1-yl)phen-yl]pyrrolidine.

The asymmetric unit of the title compound, C(14)H(12)F(8)N(2), contains one tetra-fluoro-pyrrolidine system and one half-mol-ecule of benzene; the latter, together with a second heterocyclic unit, are completed by symmetry, with a twofold crystallographic axis crossing through both the middle of the bond between the C atoms bearing the heterocyclic rings and the opposite C-C bonds of the whole benzene mol-ecule. The pyrrolidine ring shows an envelope conformation with the apex at the N atom. The dihedral angle between the least-squares plane of this ring and the benzene ring is 36.9 (5)°. There are intra-molecular C-H⋯N inter-actions generating S(6) ring motifs. In the crystal structure, the mol-ecules are linked by C-H⋯F inter-actions, forming chains parallel to [010].