Azobenzene-Based Conjugated Polymers: Synthesis, Properties, and Biological Applications.

Conjugated polymers (CPs) have been developed quickly as an emerging functional material with applications in optical and electronic devices, owing to their highly electron-delocalized backbones and versatile side groups for facile processibility, high mechanical strength, and environmental stability. CPs exhibit multistimuli responsive behavior and fluorescence quenching properties by incorporating azobenzene functionality into their molecular structures. Over the past few decades, significant progress has been made in developing functional azobenzene-based conjugated polymers (azo-CPs), utilizing diverse molecular design strategies and synthetic pathways. This article comprehensively reviews the rapidly evolving research field of azo-CPs, focusing on the structural characteristics and synthesis methods of general azo-CPs, as well as the applications of charged azo-CPs, specifically azobenzene-based conjugated polyelectrolytes (azo-CPEs). Based on their molecular structures, azo-CPs can be broadly categorized into three primary types: linear CPs with azobenzene incorporated into the side chain, linear CPs with azobenzene integrated into the main chain, and branched CPs containing azobenzene moieties. These systems are promising for biomedical applications in biosensing, bioimaging, targeted protein degradation, and cellular apoptosis.

Infrared Spectral Analysis for Prediction of Functional Groups Based on Feature-Aggregated Deep Learning.

Infrared (IR) spectroscopy is a powerful and versatile tool for analyzing functional groups in organic compounds. A complex and time-consuming interpretation of massive unknown spectra usually requires knowledge of chemistry and spectroscopy. This paper presents a new deep learning method for transforming IR spectral features into intuitive imagelike feature maps and prediction of major functional groups. We obtained 8272 gas-phase IR spectra from the NIST Chemistry WebBook. Feature maps are constructed using the intrinsic correlation of spectral data, and prediction models are developed based on convolutional neural networks. Twenty-one major functional groups for each molecule are successfully identified using binary and multilabel models without expert guidance and feature selection. The multilabel classification model can produce all prediction results simultaneously for rapid characterization. Further analysis of the detailed substructures indicates that our model is capable of obtaining abundant structural information from IR spectra for a comprehensive investigation. The interpretation of our model reveals that the peaks of most interest are similar to those often considered by spectroscopists. In addition to demonstrating great potential for spectral identification, our method may contribute to the development of automated analyses in many fields.

Cross-Reactive Fluorescent Sensor Array for Discrimination of Amyloid Beta Aggregates.

It has been hypothesized that misfolding and misassembly of proteins into various aggregation states contribute to several neurodegenerative diseases. For instance, amyloid beta (Aß) aggregation is considered a major factor in Alzheimer's disease pathogenesis. Herein, a fluorescent sensor array for detecting Aß aggregates was fabricated using two probe pairs of conjugated polyelectrolytes and organic dye molecules, PPE1-Thioflavin T (ThT) and PPESO3-Nile Red (NR). Pattern recognition was achieved by linear discriminant analysis and hierarchical clustering analysis algorithms. As a result of distinguishing among monomers and three pure aggregate species, namely oligomers, protofibrils, and fibrils, the cross-reactive sensor array was also able to monitor aggregation kinetics in various aggregate forms and distinguish between on- and off- aggregate pathways. Our study provides a convenient approach for simultaneous detection of Aß aggregates in mixtures, which may also be applied to the analysis of other disease-related proteins that are prone to aggregates.

Overlapping roles of NADPH oxidase 4 for diabetic and gadolinium-based contrast agent-induced systemic fibrosis.

Dozens of millions of people are exposed to gadolinium-based contrast agents annually for enhanced magnetic resonance imaging. Gadolinium-based contrast agents are known nephrotoxins and can trigger the potentially fatal condition of systemic fibrosis. Risk factors are practically entirely undefined. We examined the role of NADPH oxidase 4 (Nox4) in gadolinium-induced systemic disease. Age- and weight-matched mice were randomized to experimental diabetes (streptozotocin) and control groups followed by systemic gadolinium-based contrast agent treatment. Nox4-deficient mice were randomized to experimental diabetes and gadolinium-based contrast agent treatment. Skin fibrosis and cellular infiltration were apparent in both gadolinium-based contrast agent-treated and experimental diabetes groups. Similarly, both groups demonstrated renal pathologies with evidence of reactive oxygen species generation. Deletion of Nox4 abrogated both skin and renal pathology, whether from diabetes or gadolinium-based contrast agent treatment. These discoveries demonstrate the importance of Nox4 in gadolinium-based contrast agent- and diabetes-induced fibrosis.NEW & NOTEWORTHY A mouse model of gadolinium-based contrast agent- and diabetes-induced fibrosis was used to demonstrate the role of NADPH oxidase 4 (Nox4) in gadolinium-induced systemic disease. Using these models, we established the role of Nox4 as a mediator of reactive oxygen species generation and subsequent skin and kidney fibrosis. These novel findings have defined Nox-4-mediated mechanisms by which gadolinium-based contrast agents induce systemic diseases.

Mapping and Identification of Native Proteins of Developing Teeth in Mouse Mandibles.

Mass spectrometry imaging is a powerful tool of increasing utility due to its ability to spatially resolve molecular biomarkers directly from sectioned tissues. One hindrance to its universality is that no single protocol is sufficient for every tissue type, fixation, and pretreatment. Mineralized tissues are uniquely challenging as extensive decalcification protocols are necessary to achieve thin sections. In this study, we optimized a method to image tryptic peptides by matrix-assisted laser desorption ionization mass spectrometry of decalcified, formalin-fixed paraffin-embedded mouse hemimandibles. Using a combination of on-tissue MS/MS and hydrogel extraction LC-MS/MS, peptides from the enamel, dentin, periodontal ligament, alveolar bone, pulp, and other regions are identified and mapped. This breakthrough method provides a comprehensive approach to biomarker discovery in dental and craniofacial tissues which is highly relevant given that diseases originating from this region of the body are the most prevalent across all populations.

Isotope Labeling Strategies for Acylcarnitines Profile in Biological Samples by Liquid Chromatography-Mass Spectrometry.

Acylcarnitines are closely related to many metabolic diseases and likely to be good biomarkers for clinical diagnosis. Studies on acylcarnitines may help deepen the understanding of their functions associated with disease processes. However, the diversity of their structures and lack of commercial standards make them difficult to be fully detected. In this work, a highly efficient isotope labeling strategy was developed to detect acylcarnitines in biological samples using liquid chromatography-mass spectrometry (LC-MS). A pair of reagents with or without deuterium labeling tags containing both a positive charge and a primary amine group were synthesized, which were used to label the carboxyl group of acylcarnitines. The reaction was performed under mild conditions to avoid hydrolysis of acylcarnitines. The reaction products had two positive charges, forming a double charge peak in MS spectra and with mass-to-charge ratio difference (Δ m/ z) of 4.0251 Da between the light- and heavy-labeled products. The feature made it possible to distinguish signals of acylcarnitines from other carboxyl metabolites with Δ m/ z of 8.0502 Da between their light- and heavy-labeled products. On the basis of the characteristics and the tandem mass spectrometry (MS/MS) spectra, a total of 108 acylcarnitines were discovered and identified in urine samples. Our established approach will be very helpful for the studies of diseases associated with acylcarnitines metabolism.

Gadolinium-based contrast agents: Stimulators of myeloid-induced renal fibrosis and major metabolic disruptors.

Evidence for gadolinium-based contrast agent- (GBCA-) induced disease continues to mount. Risk factors for gadolinium-induced systemic fibrosis are entirely unexplored. Obesity-related renal injury is characterized by activation of glomerular mesangial cells and podocyte damage with alteration of lipid metabolism/lipid accumulation in both cell types resulting in matrix accumulation and eventual progression to glomerulosclerosis. We examined the consequences of GBCA treatment in the kidneys from mice with normal kidney function and the potential interplay between obesity and gadolinium exposure. We found that administration of GBCA (4 weeks) causes significant renal fibrosis and podocyte injury that are associated with metabolic disorders as evidenced by dyslipidemia. Metabolomic analysis demonstrated that renal lipid metabolism and metabolic markers of collagen turnover are significantly altered by gadolinium. GBCA stimulates myeloid-derived fibrocytes to the kidney. Obesity was induced by feeding a group of mice a high fat diet (HFD) for 22 weeks. Groups were sub-randomized to GBCA treatment versus none for 4 weeks before sacrifice. HFD-induced fibrosis and podocyte injury were worsened by GBCA. Similarly, HFD-mediated hyperlipidemia and lipid metabolites were exacerbated by gadolinium. This is the first evidence that GBCA causes significant metabolic disorders and kidney injury in mice without renal insufficiency and that the injurious actions of GBCA are amplified by obesity. The understanding of the functional interplay between gadolinium and obesity will allow the development of therapeutic interventions or the establishment of effective preventive measures to reduce gadolinium- and obesity-mediated renal pathologies.

Naphthalimide-containing conjugated polyelectrolytes with different chain configurations.

Several donor-acceptor type conjugated polyelectrolytes containing naphthalimide are developed. Different polymer chain configurations of the backbones of polymers lead to different photophysical properties. The para-substituted polymers show extended conformations with quite low quantum yields in high polarity solvents because of twisted intramolecular charge transfer features, while the meta-substituted polymers can form helices and demonstrated significantly improved quantum yields in water and methanol, as well as achieving sensitive, ultrafast and ratiometric detection of trace methylene blue in water.

Diagnostic and Prognostic Performance of Serum Vascular Endothelial Growth Factor, Vascular Endothelial Growth Factor Receptor 2, and Osteopontin for Gastrointestinal Cancers.

BACKGROUND: Biomarkers for early diagnosis and follow-up of cancers are still underutilized in clinical management. Thus, seeking new biomarkers with better sensitivity and specificity is still a challenge. VEGF, VEGFR2, and OPN are newly emerging biomarkers with clinical potential. METHODS: ELISA was used to analyze serum VEGF, VEGFR2, and OPN from 75 gastrointestinal cancer patients and 75 control subjects. The correlation of pre-operative serum VEGF, VEGFR2, and OPN levels with CEA, Ki-67 as well as clinical features (age, gender, tumor size, TNM stage, tumor stage, lymph node involvement, metastasis, and histological grading) in these patients. RESULTS: The pre-operative and post-operative serum VEGF and VEGFR2 levels and the post-operative OPN level in patients were significantly higher than in controls (p = 0.000, for all mentioned). The post-operative VEGF and OPN levels were significantly higher than that of pre-operative (p = 0.000 and 0.007, respectively). There was no correlation between pre-operative serum VEGF, VEGFR2, and OPN levels and serum CEA concentration. The pre-operative serum VEGF level was significantly correlated with the tumor Ki-67 scores; however, there was no correlation between serum VEGFR2 and OPN and Ki-67 scores. Univariate logistic regression analysis revealed that serum VEGF level was significantly higher in patients with advanced TNM (III - IV) stage and with lymph node involvement than in patients with low TNM stage (I - II) and with no lymph node involvement. High OPN level was correlated with metastasis. Multivariate logistic regression analysis results showed that serum VEGF and VEGFR2 were the two most important factors for the diagnosis of gastrointestinal cancers in this study (p = 0.000, for both). Combinatorial analysis of the biomarkers improved the performance of the assays. CONCLUSIONS: Serum VEGF and VEGFR2 are potential biomarkers for the diagnosis and prognosis evaluation of gastrointestinal cancers, while serum OPN is a potential biomarker for the prognostication of gastrointestinal cancers.

A New Strategy Involving the Use of Peptides and Graphene Oxide for Fluorescence Turn-on Detection of Proteins.

The detection of proteins is of great biological significance as disease biomarkers in early diagnosis, prognosis tracking and therapeutic evaluation. Thus, we developed a simple, sensitive and universal protein-sensing platform based on peptide and graphene oxide (GO). The design consists of a fluorophore (TAMRA, TAM), a peptide containing eight arginines and peptide ligand that could recognize the target protein, and GO used as a quencher. To demonstrate the feasible use of the sensor for target detection, Bcl-xL was evaluated as the model target. The sensor was proved to be sensitive and applied for the detection of the target proteins in buffer, 2% serum and living cells.

Centrality of bone marrow in the severity of gadolinium-based contrast-induced systemic fibrosis.

Systemic fibrosis can be induced in humans with gadolinium-based contrast, and cumulative doses correlate with severity. Bone marrow-derived fibrocytes accumulate in the dermis. Whether target organs liberate chemokines to recruit these fibrocytes or whether fibrocytes are stimulated to home to the affected tissue is unknown. Transgenic (tagged) donor rats were treated with gadolinium-based contrast. Bone marrow was obtained from diseased animals and age-matched controls. Rats with subtotal nephrectomies were lethally irradiated and underwent salvage transplantation with either the contrast-naïve or contrast-exposed bone marrow. Groups were randomly assigned to control or contrast treatment. Contrast treatment led to dermal fibrosis, and this was exacerbated in recipients of contrast-exposed marrow. Fibronectin, C-C chemokine receptors (CCRs)2 and 7, and oxidative stress were all increased in skin from contrast-treated animals-all parameters more severe in recipients of contrast-treated animals. The respective ligands, monocyte chemoattractant protein and C-C motif ligand 19, were both elevated in skin from contrast-treated animals. Coadministration of gadolinium-based contrast and a CCR2 inhibitor reduced the severity of skin disease as well as dermal cellularity. The functional role of chemokines in the effects of gadolinium-based contrast was further confirmed in in situ coculture studies using neutralizing CCR2 antibodies. These data implicate dermal liberation of specific chemokines in the recruitment of circulating bone marrow-derived cells. The disease is augmented by bone marrow exposure to contrast, which explains why multiple exposures correlate with severity.-Drel, V. R., Tan, C., Barnes, J. L., Gorin, Y., Lee, D.-Y., Wagner, B. Centrality of bone marrow in the severity of gadolinium-based contrast-induced systemic fibrosis.

Synthesis and biological research of novel azaacridine derivatives as potent DNA-binding ligands and topoisomerase II inhibitors.

DNA and DNA-related enzymes are one of the most effective and common used intracellular anticancer targets in clinic and laboratory studies, however, most of DNA-targeting drugs suffered from toxic side effects. Development of new molecules with good antitumor activity and low side effects is important. Based on computer aided design and our previous studies, a series of novel azaacridine derivatives were synthesized as DNA and topoisomerases binding agents, among which compound 9 displayed the best antiproliferative activity with an IC50 value of 0.57µM against U937 cells, which was slightly better than m-AMSA. In addition, compound 9 displayed low cytotoxicity against human normal liver cells (QSG-7701), the IC50 of which was more than 3 times lower than m-AMSA. Later study indicated that all the compounds displayed topoisomerases II inhibition activity at 50µM. The representative compound 9 could bind with DNA and induce U937 apoptosis through the exogenous pathway.

Synthesis and investigation of novel 6-(1,2,3-triazol-4-yl)-4-aminoquinazolin derivatives possessing hydroxamic acid moiety for cancer therapy.

By merging the critical pharmacophore of EGFR/HER2 and HDAC inhibitors into one compound, a novel series of EGFR, HER-2, and HDAC multitarget inhibitors were synthesized. Compounds 9a-l contained 4-anilinoquinazolines with C-6 triazole-linked long alkyl chains of hydroxamic acid and displayed excellent inhibition against these enzymes (compound 9d exhibited the best inhibitory potency on wild-type EGFR, HDAC1, and HDAC6 with IC50 values 0.12nM, 0.72nM and 3.2nM individually). Furthermore, compounds 9b and 9d potently inhibited proliferation of five human cancer cell lines (with IC50 values between 0.49 and 8.76µM). Further mechanistic study revealed that compound 9d also regulated the phosphorylation of EGFR and HER2 and histone H3 hyperacetylation on the cellular level and induced remarkable apoptosis in BT-474 cells. Therefore, our study suggested that a system network-based multi-target drug design strategy might provided an alternate drug design method, by taking into account the synergy effect of EGFR, HER-2 and HDAC.

Olaparib hydroxamic acid derivatives as dual PARP and HDAC inhibitors for cancer therapy.

Olaparib was the first PARP inhibitor approved by the FDA for patients with BRCA-mutated ovarian cancer. Recent studies have demonstrated enhanced anticancer effects of combination therapy consisting of olaparib and HDAC inhibitors. Herein, based on rational drug design strategy, hydroxamic acid derivatives of olaparib were constructed as dual PARP and HDAC inhibitors. These hybrid compounds showed potent inhibitory activities against PARP1/2 and HDAC1/6 with IC50 values in the nanomolar range. Furthermore, compound P1 exhibited broad-spectrum antiproliferative activities in selected human cancer cell lines. Specially, P1 showed more potent activity than olaparib and SAHA in cancer cells MDA-MB-231, HCC1937 and Raji, and 4.1-fold less cytotoxicity compared with SAHA to normal cells MCF-10A. Further mechanism study indicated that P1 could induce the cleavage of PARP and the hyperacetylation of histones, increase the expression of DNA damage biomarker γ-H2AX, decrease the level of BRCA1 and RAD51, and regulate tumor cell growth and apoptosis through modulating both mitochondrial- and death receptor-mediated pathways. Therefore, our study suggested that compounds targeting PARP and HDAC concurrently might be a practical approach for cancer therapy.

Matrix metalloproteinase-1 promoter -1607 bp 1G/2G polymorphism associated with increased risk of spinal tuberculosis in Southern Chinese Han population.

BACKGROUND: Spinal tuberculosis is the most common form of musculoskeletal tuberculosis. The expression of matrix metalloproteinase-1 (MMP-1) is increased in cells with Mycobacterium tuberculosis infection. MMP-1 plays a curial role in extracellular matrix degradation during the progression of tuberculosis. Although the 1G/2G polymorphism in MMP-1-1607 influences its transcription, its role in spinal tuberculosis remains unknown. METHODS: Healthy controls and patients with spinal tuberculosis of Han ethnicity were recruited between January 2010 and May 2016. The MMP-1-1607 1G/2G polymorphism was genotyped using the Sequenom mass Array polymorphism analysis system. RESULTS: The genotypes of 1G/1G, 1G/2G, and 2G/2G were found in 13.7%, 53.6%, and 32.8% of patients, and 12.2%, 37.4%, and 50.4% of controls, respectively. The 1G/2G genotype were more common in cases than in controls (P=2.05E-04). The 1G allele showed an association with an increased risk for spinal tuberculosis when compared to 2G allele (P=.004). 1G genotypes, having at least one 1G allele, were associated with the risk of developing spinal tuberculosis (1G/1G+1G/2G vs 2G/2G: OR=2.084, 95%CI=1.401-3.100, P=2.65E-04). CONCLUSION: 1G genotypes of the MMP-1-1607 may be associated with susceptibility to spinal tuberculosis in Southern Chinese Han population.

The Optimization and Characterization of an RNA-Cleaving Fluorogenic DNAzyme Probe for MDA-MB-231 Cell Detection.

Breast cancer is one of the most frequently diagnosed cancers in females worldwide and lacks specific biomarkers for early detection. In a previous study, we obtained a selective RNA-cleaving Fluorogenic DNAzyme (RFD) probe against MDA-MB-231 cells, typical breast cancer cells, through the systematic evolution of ligands by exponential process (SELEX). To improve the performance of this probe for actual application, we carried out a series of optimization experiments on the pH value of a reaction buffer, the type and concentration of cofactor ions, and sequence minimization. The length of the active domain of the probe reduced to 25 nt from 40 nt after optimization, which was synthesized more easily and economically. The detection limit of the optimized assay system was 2000 MDA-MB-231 cells in 30 min, which is more sensitive than the previous one (almost 5000 cells). The DNAzyme probe was also capable of distinguishing MDA-MB-231 cell specifically from 3 normal cells and 10 other tumor cells. This probe with high sensitivity, selectivity, and economic efficiency enhances the feasibility for further clinical application in breast cancer diagnosis. Herein, we developed an optimization system to produce a general strategy to establish an easy-to-use DNAzyme-based assay for other targets.

NADPH oxidase 4 induces cardiac fibrosis and hypertrophy through activating Akt/mTOR and NFκB signaling pathways.

BACKGROUND: NADPH oxidase 4 (Nox4) has been implicated in cardiac remodeling, but its precise role in cardiac injury remains controversial. Furthermore, little is known about the downstream effector signaling pathways activated by Nox4-derived reactive oxygen species in the myocardium. We investigated the role of Nox4 and Nox4-associated signaling pathways in the development of cardiac remodeling. METHODS AND RESULTS: Cardiac-specific human Nox4 transgenic mice (c-hNox4Tg) were generated. Four groups of mice were studied: (1) control mice, littermates that are negative for hNox4 transgene but Cre positive; (2) c-hNox4 Tg mice; (3) angiotensin II (AngII)-infused control mice; and (4) c-hNox4Tg mice infused with AngII. The c-hNox4Tg mice exhibited an ≈10-fold increase in Nox4 protein expression and an 8-fold increase in the production of reactive oxygen species, and manifested cardiac interstitial fibrosis. AngII infusion to control mice increased cardiac Nox4 expression and induced fibrosis and hypertrophy. The Tg mice receiving AngII exhibited more advanced cardiac remodeling and robust elevation in Nox4 expression, indicating that AngII worsens cardiac injury, at least in part by enhancing Nox4 expression. Moreover, hNox4 transgene and AngII infusion induced the expression of cardiac fetal genes and activated the Akt-mTOR and NFκB signaling pathways. Treatment of AngII-infused c-hNox4Tg mice with GKT137831, a Nox4/Nox1 inhibitor, abolished the increase in oxidative stress, suppressed the Akt-mTOR and NFκB signaling pathways, and attenuated cardiac remodeling. CONCLUSIONS: Upregulation of Nox4 in the myocardium causes cardiac remodeling through activating Akt-mTOR and NFκB signaling pathways. Inhibition of Nox4 has therapeutic potential to treat cardiac remodeling.

Proteolysis targeting peptide (PROTAP) strategy for protein ubiquitination and degradation.

Ubiquitination proteasome pathway (UPP) is the most important and selective way to degrade proteins in vivo. Here, a novel proteolysis targeting peptide (PROTAP) strategy, composed of a target protein binding peptide, a linker and a ubiquitin E3 ligase recognition peptide, was designed to recruit both target protein and E3 ligase and then induce polyubiquitination and degradation of the target protein through UPP. In our study, the PROTAP strategy was proved to be a general method with high specificity using Bcl-xL protein as model target in vitro and in cells, which indicates that the strategy has great potential for in vivo application.

Fluorescence array-based sensing of nitroaromatics using conjugated polyelectrolytes.

A sensor array consisting of six cationic fluorescent conjugated polyelectrolytes (CPEs) is reported, which could readily differentiate between nine closely related hydrophilic nitroaromatics (NACs) in separate aqueous solutions by fluorescence pattern recognition and linear discrimination analysis (LDA).

Design, synthesis and evaluation of acridine derivatives as multi-target Src and MEK kinase inhibitors for anti-tumor treatment.

Clinical studies have shown enhanced anticancer effects of combined inhibition of Src and MEK kinases. Development of multi-target drugs against Src and MEK is of potential therapeutic advantage against cancers. As a follow-up of our previous studies, and by using molecular docking method, we designed and synthesized a new series of 9-anilinoacridines containing phenyl-urea moieties as potential novel dual Src and MEK inhibitors. The anti-proliferative assays against K562 and HepG-2 tumor cells showed that most of the derivatives displayed good cytotoxicity in vitro. In particular, kinase inhibition assays showed that compound 8m inhibited Src (59.67%) and MEK (43.23%) at 10 µM, and displayed moderate inhibitory activity against ERK and AKT, the downstream effectors of both Src and MEK. Moreover, compound 8m was found to induce K562 cells apoptosis. Structure-activity relationships of these derivatives were analyzed. Our study suggested that acridine scaffold, particularly compound 8m, is of potential interest for developing novel multi-target Src and MEK kinase inhibitors.