D-A-D type based NIR fluorescence probe for monitoring the cysteine levels in pancreatic cancer cell during ferroptosis.

Cysteine (Cys) as a crucial precursor for intracellular glutathione (GSH) synthesis, plays an important role in the redox regulation in ferroptosis, Therefore, evaluating intracellular Cys levels is worthy to better understand ferroptosis-related physiological process. In this work, we constructed a novel NIR coumarin-derived fluorescent probe (NCDFP-Cys) based on a dual-ICT system, the NCDFP-Cys can show fluorescence turn-on response at 717 nm toward Cys over other amino acids, and possess large Stokes shift (Δλ = 167 nm), low detection limit, hypotoxicity. More significantly, NCDFP-Cys has been utilized to monitor the intracellular Cys fluctuation in pancreatic cancer cells during ferroptosis induced by Erastin and RSL3 respectively, and revealing the difference of Cys levels changes in different activator-triggered ferroptosis pathways.

A Nucleic Acid-Based LYTAC Plus Platform to Simultaneously Mediate Disease-Driven Protein Downregulation.

Protein degradation techniques, such as proteolysis-targeting chimeras (PROTACs) and lysosome-targeting chimeras (LYTACs), have emerged as promising therapeutic strategies for the treatment of diseases. However, the efficacy of current protein degradation methods still needs to be improved to address the complex mechanisms underlying diseases. Herein, a LYTAC Plus hydrogel engineered is proposed by nucleic acid self-assembly, which integrates a gene silencing motif into a LYTAC construct to enhance its therapeutic potential. As a proof-of-concept study, vascular endothelial growth factor receptor (VEGFR)-binding peptides and mannose-6 phosphate (M6P) moieties into a self-assembled nucleic acid hydrogel are introduced, enabling its LYTAC capability. Small interference RNAs (siRNAs) is then employed that target the angiopoietin-2 (ANG-2) gene as cross-linkers for hydrogel formation, giving the final LYTAC Plus hydrogel gene silencing ability. With dual functionalities, the LYTAC Plus hydrogel demonstrated effectiveness in simultaneously reducing the levels of VEGFR-2 and ANG-2 both in vitro and in vivo, as well as in improving therapeutic outcomes in treating neovascular age-related macular degeneration in a mouse model. As a general material platform, the LYTAC Plus hydrogel may possess great potential for the treatment of various diseases and warrant further investigation.

Facile Synthesis of Black Phosphorus Nanosheet@NaReF4 Nanocomposites for Potential Bioimaging.

Black phosphorus nanomaterials (BPN) have been well developed in tumor therapy. However, lack of diagnostic function limits the development of BPN in biomedicine. Lanthanide-doped nanoparticles are considered as versatile materials for fluorescence or magnetic resonance imaging. Integration of BPN with lanthanide-doped nanoparticles was rarely reported owing to the complex synthesis processes and poor modification effect. Herein, we report a simple and general method for synthesizing BPN@NaReF4 (Re: Gd or Y, Yb, Er) nanocomposite. TEM and XRD characterization confirm efficient combination of BPN and NaGdF4 or NaYF4:Yb,Er (18.2 mol %) after one-step mixing. The FTIR and XPS spectra were used to prove the generation of PO43--Gd and P-Gd coordination bonds and clarify ligand exchange mechanism. The anchored nanoparticles on BPN were stable and become hydrophilic. The prepared BPN@NaGdF4 exhibit the signals of photoacoustic and magnetic resonance imaging. The obtained BPN@NaYF4:Yb,Er (18.2 mol %) have the potential in fluorescence bioimaging. We believe that this work will expand the applications of BPN in diagnosis and therapy together.

Galactosed and Reduction-Responsive Nanoparticles Assembled from Trimethylchitosan-Camptothecin Conjugates for Enhanced Hepatocellular Carcinoma Therapy.

The targeted delivery of drugs to tumor cells and prevention of premature release before reaching the target is one of the key challenges to developing nanomedicines. In this paper, galactose decorated trimethyl chitosan (GT)-camptothecin (CPT) prodrug nanoparticles (GT-ss-CPT NPs) were prepared from GT-CPT conjugates linked by dithiodipropionic acid. The obtained GT-ss-CPT NPs were spherical with a particle size of 184.1 nm. GT-ss-CPT NPs displayed low drug release under physiological conditions, whereas efficient drug release was triggered by high GSH concentration. GT-ss-CPT NPs exhibited a higher antitumor effect both in vitro and in vivo than the free drug counterpart. More importantly, GT-ss-CPT NPs reduced the high systematic toxicity of CPT to tumor-bearing mice. In summary, GT-ss-CPT NPs can not only inhibit the premature release of CPT but also have a great potential for targeted hepatocellular carcinoma chemotherapy.

Urokinase loaded black phosphorus nanosheets for sequential thrombolysis and reactive oxygen species scavenging in ischemic stroke treatment.

Ischemic stroke often causes devastating damage to human life and health. Excess production of reactive oxygen species (ROS) during thrombolysis will paradoxically result in neuronal injury. Neuroprotection from reperfusion injury must overcome the challenge of crossing the blood-brain barrier (BBB). A strategy including thrombolysis and ROS scavenging accompanied by BBB penetration is highly desirable for improving combination therapies in ischemic stroke. Herein, urokinase plasminogen activator (uPA) loaded on black phosphorus nanosheets (BPNs) is tested as a nanodrug for sequential thrombolysis and neuroprotection. The in vitro thrombolysis shows that the uPA-loaded BPNs can efficiently deliver uPA for thrombus dissolution. The residual BPNs after uPA release exhibit ROS scavenging effects, especially for the most common H2O2 and ˙OH species. Moreover, in vivo studies show that the BPNs can cross the BBB with the assistance of laser irradiation, owing to their good photothermal properties. Further experiments show the effectiveness of BPNs for attenuating reperfusion injury and achieving neuroprotection. These results highlight the promising potential of the present BPN-based nanodrugs for the treatment of ROS-related diseases.

Rational Construction of a Two-Photon NIR Ratiometric Fluorescent Probe for the Detection of Bisulfite in Live Cells, Tissues, and Foods.

In this study, we report a novel ratiometric fluorescent probe with a blue shift of 180 nm based on a D-π-A-A structure. The probe composed of a hydroxyl moiety as a donor, a naphthyl ring as a π bridge, and benzothiazole/hemicyanine as an acceptor has good selectivity and high sensitivity to bisulfite (HSO3-) in aqueous solution. Besides one-photon fluorescence properties, the probe possesses excellent two-photon fluorescence properties and is successfully utilized for fluorescence imaging of HSO3- in MCF-7 cells and rat liver tissues. More importantly, the probe also has practical application potential for measuring the HSO3- content of real food samples.

A novel long excitation/emission wavelength fluorophore as platform utilized to construct NIR probes for bioimaging and biosensing.

Near-infrared (NIR) fluorophores, especially dicyano-based fluorophores and xanthene-based hemicyanines, have beenput high expectation in bioimaging application due to their excellent optical properties. However, they suffer from inherentshortagessuch as short excitation/emission wavelength (less than 700 nm) or small Stokes shift (20-50 nm). Herein, we constructed a novel NIR dicyano-based fluorophore (DCO-HBTN). Toourknowledge, it is the first reported dicyano-based fluorophore of which the excitation/emission wavelength is more than 650 nm and Stokes shift is more than 100 nm. To demonstrate the feasibility of our efforts, we developed two NIR fluorescent probes (Probe-Cys and Probe-H2S) based on the fluorophore, Probe-Cys displayed good selective and highly sensitive (LOD = 0.28 µM) recognition of Cys over Hcy and GSH, which was used to visualize endogenous Cys in tumor tissue. Probe-H2S exhibited an. excellent specific and sensitive (LOD = 0.11 µM) response to H2S, which was applied in monitoring H2S releasing from the prodrug in vitro and in vivo.

Plaque-Targeted Rapamycin Spherical Nucleic Acids for Synergistic Atherosclerosis Treatment.

Atherosclerosis with unstable plaques is the dominant pathological basis of lethal cardio-cerebrovascular diseases, which can cause acute death due to the rupture of plaques. Plaque-targeted drug delivery to achieve promoted treatment remains the main challenge because of the systemic occurrence of atheroma. Herein, a rapamycin (RAP) spherical nucleic acid (SNA) structure, capable of specifically accumulating in plaques for synergistic atherosclerosis treatment is constructed. By designing consecutive phosphorothioate (PS) at 3' terminus of the deoxyribonucleic acid (DNA) strand, multiple hydrophobic RAPs are covalently grafted onto the PS segment to form an amphiphilic drug-grafted DNA (RAP-DNA), which successively self-assembles into micellar SNA (RAP-SNA). Moreover, the phosphodiester-DNA segment constitutes the outer shell of RAP-SNA, enabling further hybridization with functional siRNA (targeting lectin-like oxidized low-density lipoprotein receptor-1, LOX-1) to obtain the drug codelivered SNA (LOX-1/RAP-SNA). With two active ingredients inside, LOX-1/RAP-SNA can not only induce robust autophagy and decrease the evil apoptosis of the pathological macrophages, but also simultaneously prohibit the LOX-1-mediated formation of damageable foam cells, realizing the effect of synergistic therapy. As a result, the LOX-1/RAP-SNA significantly reduces the progression of atheroma and stabilizes the plaques, providing a new strategy for synergistically targeted atherosclerosis treatment.

Manganese(II) EOB-Pyclen Diacetate for Liver-Specific MRI.

MRI is increasingly utilized for the diagnosis of liver disease and focal liver lesions. Although liver-targeted gadolinium-based contrast agents (GBCAs) have high efficacy, there continue to be safety concerns regarding release of toxic Gd(III) ions. Herein, Mn(EOB-PC2A) is synthesized as a nongadolinium alternative for liver-specific MRI. Mn(EOB-PC2A) has an r1 relaxivity of 2.8 mM-1 s-1 in Dulbecco's phosphate-buffered saline (DPBS) and 5.9 mM-1 s-1 in saline containing human serum albumin at 1.5 T. It has a strong uptake in hepatocytes with minimal toxicity and demonstrated robust liver-specific enhancement at a dose of 60 µmol/kg. Mn(EOB-PC2A) is a promising liver-specific contrast agent for liver MRI.

Synthesis and preliminary exploration of a NIR fluorescent probe for the evaluation of androgen dependence of prostate cancer.

PURPOSE: Castration resistance prostate cancer patients showing resistance to the androgen deprivation therapy always have low five-year survival rate and worse prognosis. A responsive NIR fluorescent probe was designed to report the androgen dependence and monitor the development of castration resistance for prostate cancer. METHODS: Intratumoral H2S in prostate cancer was closely related to castration resistance. A H2S-responsive NIR probe (HM) was developed as a dependent indicator to report the androgen dependence of prostate cancer. The specificity of HM to H2S and the influence of normal intracellular substrates to the response between H2S and HM were determined. Cell/in vivo animal imaging were performed on PC-3 and LnCAP cell/tumor bearing mice, which presented with androgen independence and androgen dependence, respectively. RESULTS: When HM responded to H2S, strong fluorescence at 770 nm could be rapidly turned on in 5 min with the stokes shift as large as 200 nm. The recognition between HM and H2S showed high specificity. Neither other common substrates showed capacity to turn on HM's fluorescence, nor their existence demonstrated competition. The fluorescence intensity was linearly dependent to the H2S concentration and the limited of detection was 0.15 µM. When HM was applied to PC-3/LNCaP prostate cancer cell and tumor, the intracellular and intratumoral H2S could be clearly imaged and monitored. CONCLUSION: HM showing obvious fluorescent behaviors in androgen dependence and independence prostate tumor, which could work as an indicator to reported the androgen dependence of prostate cancer and monitor the development of castration resistance.

Development of a NIR fluorescent probe for the detection of intracellular cysteine and glutathione and the monitoring of the drug resistance.

Intracellular cysteine and glutathione was deemed as the most important reductants in the cell and played significant roles in the cellular homeostasis and redox adjustment. Here we developed a NIR fluorescent probe (HI) to detect and report the intracellular cysteine and glutathione, and monitor the development of the drug resistance of tumor. HI with both excited wavelength and emitting wavelength located within near infrared area showed no fluorescence in the normal physiological environment. However, when HI responded to cysteine and glutathione, strong NIR fluorescence could be turned on, which was linear dependent to the cysteine concentrations and the limited of detection was 0.18 µM. The response between HI and cysteine/glutathione demonstrated high specificity and no other amino acids showed influence or competition. The HPLC identification of the recognition results confirmed the response of acryloyloxy on the HI and active sulfhydryl on the cysteine/glutathione. DFT calculation of the HOMO and LUMO energy before and after response revealed the intramolecular charge transfer mechanism that induced the generation of the fluorescence. When HI was incubated with PATU-8988 and PATU-8988/Fu cell, the intracellular cysteine and glutathione could be clearly imaged and monitored by the enhanced fluorescence. Meanwhile, when HI was applied to the tumor-bearing mice, the drug resistance of tumor could be monitored and reported.

Two similar Schiff-base receptor based quinoline derivate: Highly selective fluorescent probe for Zn(II).

As is known, Zn2+ plays a vital role in a variety of biological processes but excessive exposure of Zn2+ to human beings can cause toxicity, inducing a series of overt poisoning symptoms and neurodegenerative disorders. Thus, we designed and synthesized two quinoline-derived Schiff-bases HL1 and HL2, and investigated the fluorescence emission responses of these two Schiff-bases to various metal ions. A significant enhancement in fluorescence emission band centered at 450 nm was observed in the ethanolic solution of HL1 with addition of Zn2+, while remarkably lower fluorescence emission enhancement was obtained in the case of HL2 in which one methyl group was introduced to the azomethine carbon. In addition, HL1 showed good selectivity and high sensitivity towards Zn2+ in the existence of other various interfering metal ions, and the reversibility and regeneration of HL1 were also perfect for extending its applications in environmental and biological systems. Therefore, HL1 could be identified as a fluorescent probe for sensing Zn2+ environmentally and biologically.

Study on synthesis and fluorescence property of rhodamine-naphthalene conjugate.

In this study, a novel ligand (HL) consisting of 2-methyl quinoline-4-carboxylic acid, rhodamine and naphthalene moiety, was designed and synthesized, it could be developed a ratiometric fluorescent sensor for selective detection of Al3+ via fluorescence resonance energy transfer (FRET) from naphthalimide moiety to rhodamine moiety. The addition of Al3+ trigger the significant fluorescence enhancement of HL at 550 nm at the expense of the fluorescent emission of HL centered at 524 nm.

Synthesis and assessment of ZD2-(68Ga-NOTA) specific to extradomain B fibronectin in tumor microenvironment for PET imaging of pancreatic cancer.

Patients diagnosed with pancreatic cancer at a late stage have a dismal survival rate. Accurate early detection of pancreatic cancer with a size of 10 mm or less could dramatically improve patient survival after timely treatments. We have developed a new PET probe ZD2-(68Ga-NOTA) specific to extradomain-B fibronectin (EDB-FN), an oncoprotein in tumor microenvironment, for sensitive molecular imaging and early diagnosis of pancreatic cancer. A targeted ligand ZD2-NOTA is synthesized by conjugation of a macrocyclic ligand NOTA via a 6-aminohexanoic acid spacer to a linear ZD2 peptide (Thr-Val-Arg-Thr-Ser-Ala-Asp). ZD2-(68Ga-NOTA) is synthesized by relabeling of ZD2-NOTA with 68GaCl3 in a high purity under GMP conditions. The expression of EDB-FN is demonstrated in BxPC3 and Capan-1 human pancreatic cancer cells and tumor xenografts in mice. ZD2-(68Ga-NOTA) results in significantly higher uptake in the both BxPC3 and Capan-1 tumor xenografts than normal organs and tissues, including the brain, heart, liver and muscle, at 1 hr postinjection in mice. The tumor to muscle uptake ratio is at least 5 folds for the tracer in both tumors. ZD2-(68Ga-NOTA) is able to clearly delineate the PaCa tumors with a size of 10 mm or less with minimal background noise in normal tissues, including the liver. Substantial tumor uptake is still visible at 2 hr post-injection. The results suggest that the ZD2 peptide targeted PET probe has a potential for sensitive molecular imaging of EDB-FN and early detection of pancreatic cancer to improve healthcare of the patients diagnosed with the disease.

A Schiff-base receptor based chromone derivate: Highly selective fluorescent and colorimetric probe for Al(III).

Upon excitation of the visible light, probes show colorimetric and fluorescent responses to the specific metal ion, which can be easily detected by the naked eye. Owing to the excitation of the visible light at 423 nm, a novel and simple Schiff-base receptor based chromone derivative called 7-methoxychromone-3-carbaldehyde-(indole-3-formyl) hydrazone (MCIH2) had been investigated as a selective and sensitive probe for Al3+ with colorimetric and fluorescent responses. Upon addition of Al3+ to compound MCIH2 solution, compound MCIH2 could respond to Al3+ with a good selective colorimetric signal, which was easily observed from colorless to yellow-green by the naked eye. Furthermore, a remarkable fluorescence emission enhancement with an "OFF-ON" signal by over 700-fold was triggered, but other various metal ions had no such significant effects on the fluorescence emission. In addition, the detection limit of compound MCIH2 for recognizing Al3+ was evaluated to be as low as 1 × 10-7 M level, which was sufficiently low for sensing Al3+ widely distributed in various environmental and biological systems.

Optimization of ZD2 Peptide Targeted Gd(HP-DO3A) for Detection and Risk-Stratification of Prostate Cancer with MRI.

The aim of this work is to optimize a peptide targeted macrocyclic MRI contrast agent for detection and risk-stratification of aggressive prostate cancer. The optimized agent was prepared using click chemistry in the presence of CuSO4 and ascorbate at room temperature. The T1 and T2 relaxivities of ZD2-N3-Gd(HP-DO3A) are 5.44 and 7.10 mM-1 s-1 at 1.4 T, and 5.53 and 7.81 mM-1 s-1 at 7 T, respectively, higher than the previously reported ZD2-Gd(HP-DO3A). The specific tumor enhancement of the agent was investigated in male nude mice bearing aggressive PC3 human prostate cancer xenografts and slow-growing LNCaP tumor xenografts. Contrast enhanced MR images were acquired using a 2D spin-echo sequence and a 3D FLASH sequence with a 7 T small animal scanner. ZD2-N3-Gd(HP-DO3A) produced robust contrast enhancement in aggressive PC3 tumors and little enhancement in slow-growing LNCaP tumors. It produced 400% and 100% CNR increases in the T1-weighted 2D spin-echo MR images and 3D FLASH images of PC3 tumors, respectively, for at least 30 min at a dose of 0.1 mmol/kg. In contrast, less than 20% CNR increase was observed in the LNCaP tumors with both sequences. The optimized targeted contrast agent has higher relaxivities and are effective to detect aggressive PC3 tumors and differentiate the aggressive cancer from the slow-growing LNCaP prostate cancer in contrast enhanced MRI. ZD2-N3-Gd(HP-DO3A) has the promise for accurate detection and risk-stratification of aggressive prostate cancer.

A Novel Chromone Schiff-Base Fluorescent Chemosensor for Cd(II) Based on C=N Isomerization.

A new chromone Schiff-base fluorescent probe 7'-methoxychromone-3'-methylidene-1,2,4-triazole-3-imine (L) was designed and synthesized for selective recognition Cd(2+). With the fluorescence titration and the ESI-MS data, we reach the conclusion that the binding mode of the ligand-metal (L-Cd (2+) ) complex is 1:1. The sensor showed a strong fluorescence enhancement in ethanol system of Cd(2+) (excitation 409 nm and emission 462 nm) and the sensing mechanism based on the fact that C=N isomerization can be used to explain this phenomenon.

A Chromone-Derived Schiff-Base Ligand as Al(3+) "Turn on" Fluorescent Sensor: Synthesis and Spectroscopic Properties.

In this study, a novel chromone-derived Schiff-base ligand called 6-Hydroxy-3-formylchromone (2'-furan formyl) hydrazone (HCFH) has been designed and synthesized as a "turn on" fluorescent sensor for Al(3+). This sensor HCFH showed high selectivity and sensitivity towards Al(3+) over other metal ions investigated, and most metal ions had nearly no influences on the fluorescence response of HCFH to Al(3+). Additionally, the significant enhancement by about 171-fold in fluorescence emission intensity at 502 nm was observed in the presence of Al(3+) in ethanol, and it was due to the chelation-enhanced fluorescence (CHEF) effect upon complexation of HCFH with Al(3+) which inhibited the photoinduced electron transfer (PET) phenomenon from the Schiff-base nitrogen atom to chromone group. Moreover, this sensor formed a 1 : 1 complex with Al(3+) and the fluorescence response of HCFH to Al(3+) was nearly completed within 1 min. Thus, this sensor HCFH could be used to detect and recognize Al(3+) for real-time detection.

Two Schiff-base fluorescent sensors for selective sensing of aluminum (III): Experimental and computational studies.

Two Schiff-base fluorescent sensors have been synthesized, which both can act as fluorescent probes for Al(3+), upon addition of Al(3+), they exhibit a large fluorescence enhancement which might be attributed to the formation of 1:1 ligand-Al complexes which inhibit photoinduced electron transfer (PET) progress, and that the proposed binding modes of the sensors and Al(3+) are identified by theoretical calculations.

Design of a novel coumarin-based multifunctional fluorescent probe for Zn²âº/Cu²âº/S²â» in aqueous solution.

A multifunctional fluorescent chemosensor 7-(diethylamino)-coumarin-3-carbaldehyde-(2'-methylquinoline-4'-formyl) hydrazone (HL) has been designed and synthesized. The sensor shows significant fluorescence enhancement in the presence of Zn(2+), which might be mainly due to the restricted -CN isomerization process. In contrast, the fluorescence of the sensor is quenched by Cu(2+) attributed to the inherent paramagnetic species. More interestingly, the 'in situ' prepared L-Cu exhibits a selective response to S(2-) based on reversible formation-separation of complex L-Cu and CuS.