Enhanced Terahertz Fingerprint Sensing Mechanism Study of Tiny Molecules Based on Tunable Spoof Surface Plasmon Polaritons on Composite Periodic Groove Structures.

Highly sensitive detection of enhanced terahertz (THz) fingerprint absorption spectrum of trace-amount tiny molecules is essential for biosensing. THz surface plasmon resonance (SPR) sensors based on Otto prism-coupled attenuated total reflection (OPC-ATR) configuration have been recognized as a promising technology in biomedical detection applications. However, THz-SPR sensors based on the traditional OPC-ATR configuration have long been associated with low sensitivity, poor tunability, low refractive index resolution, large sample consumption, and lack of fingerprint analysis. Here, we propose an enhanced tunable high-sensitivity and trace-amount THz-SPR biosensor based on a composite periodic groove structure (CPGS). The elaborate geometric design of the spoof surface plasmon polaritons (SSPPs) metasurface increases the number of electromagnetic hot spots on the surface of the CPGS, improves the near-field enhancement effect of SSPPs, and enhances the interaction between THz wave and the sample. The results show that the sensitivity (S), figure of merit (FOM) and Q-factor (Q) can be increased to 6.55 THz/RIU, 4234.06 1/RIU and 629.28, respectively, when the refractive index range of the sample to measure is between 1 and 1.05 with the resolution 1.54×10-5 RIU. Moreover, by making use of the high structural tunability of CPGS, the best sensitivity (SPR frequency shift) can be obtained when the resonant frequency of the metamaterial approaches the biological molecule oscillation. These advantages make CPGS a strong candidate for the high-sensitivity detection of trace-amount biochemical samples.

Output Enhancement of Triboelectric Nanogenerators Based on Hierarchically Regular Cadmium Coordination Polymers for Photocycloaddition.

Exploiting the well-arranged and tunable frameworks of crystalline materials, we herein report coordination polymers (CPs) with modulated hierarchical structures as triboelectric materials to construct and extend the application scope of triboelectric nanogenerators (TENGs). Different lengths and shapes of bridging ligands [4,4'-bpa = 1,2-bis(4-pyridyl)ethane, 4,4'-bpe = 1,2-bis(4-pyridyl)ethene, and 4,4'-bpp = 1,3-di(2-pyridyl)propane for 1, 2, and 3, respectively] were used to construct Cd-CP-based hierarchical frameworks. These compounds were used as triboelectric materials, and their electronic structure contributions were determined by the output of the corresponding TENGs. The results indicated that 2-TENG with the 4,4'-bpe ligand had the highest output, attributed to the improvement in the electron activity due to the π-conjugation group in the bridging ligand, which was further verified by density functional theory calculations. Furthermore, 2@PVDF (PVDF = polyvinylidene fluoride) composite films with different concentrations of Cd-CP were prepared. Detailed electrical characterizations revealed that the arrangement of 12% active constituents of Cd-CP-2 effectively enhanced the output performance of 2@PVDF-TENG, which could light up an ultraviolet lamp plate to successfully execute the [2 + 2] photocycloaddition.

Programmable Triboelectric Nanogenerators Dependent on the Secondary Building Units in Cadmium Coordination Polymers.

Precisely controlling the coordination microenvironment and electronic features of polynuclear secondary building units (SBUs) in coordination polymers (CPs) is an efficient approach to governing their fundamental performance. Here, different multinuclear SBUs (binuclear, trinuclear, and pentanuclear SBUs for 1-3, respectively) were introduced into Cd-based CPs, which were used as frictional electrode materials, to clarify the contributions of polynuclear Cd-SBUs through the output of triboelectric nanogenerators (TENGs). The results demonstrated that 1-TENG with binuclear Cd-SBUs possessed the highest output, whereas 3-TENG with the pentanuclear Cd-SBUs indicated the minimum output, suggesting that the binuclear Cd-SBUs in 1 lost electrons most readily and generated much more charge, which was further confirmed by density functional theory calculations. This work opened a new prospect to confirm the gaining/losing capability of polynuclear Cd-SBUs in CPs and provided an effective approach to tuning both the stability and functionality of polynuclear CPs as frictional pair materials to regulate the output of CPs-based TENGs.

Cathepsin Inhibition Prevents Autophagic Protein Turnover and Downregulates Insulin Growth Factor-1 Receptor-Mediated Signaling in Neuroblastoma.

Inhibition of the major lysosomal proteases, cathepsins B, D, and L, impairs growth of several cell types but leads to apoptosis in neuroblastoma. The goal of this study was to examine the mechanisms by which enzyme inhibition could cause cell death. Cathepsin inhibition caused cellular accumulation of fragments of the insulin growth factor 1 (IGF-1) receptor. The fragments were located in dense organelles that were characterized as autophagosomes. This novel discovery provides the first clear link between lysosomal function, autophagy, and IGF-1- mediated cell proliferation. A more in-depth analysis of the IGF1 signaling pathway revealed that the mitogen-activated protein kinase (MAPK) cell-proliferation pathway was impaired in inhibitor treated cells, whereas the Akt cell survival pathway remained functional. Shc, an adapter protein that transmits IGF-1 signaling through the MAPK pathway, was sequestered in autophagosomes; whereas IRS-2, an adapter protein that transmits IGF-1 signaling through the Akt pathway, was unaffected by cathepsin inhibition. Furthermore, Shc was sequestered in autophagosomes as its active form, indicating that autophagy is a key mechanism for downregulating IGF-1-induced cell proliferation. Cathepsin inhibition had a greater effect on autophagic sequestration of the neuronal specific adapter protein, Shc-C, than ubiquitously expressed Shc-A, providing mechanistic support for the enhanced sensitivity of neuronally derived tumor cells. We also observed impaired activation of MAPK by epidermal growth factor treatment in inhibitor-treated cells. The Shc adapter proteins are central to transducing proliferation signaling by a range of receptor tyrosine kinases; consequently, cathepsin inhibition may become an important therapeutic approach for treating neuroblastoma and other tumors of neuronal origin.

Inhibitors of cathepsins B and L induce autophagy and cell death in neuroblastoma cells.

This study was designed to test the hypothesis that specific inhibition of cathepsins B and L will cause death of neuroblastoma cells. Five compounds that differ in mode and rate of inhibition of these two enzymes were all shown to cause neuroblastoma cell death. Efficacy of the different compounds was related to their ability to inhibit the activity of the isolated enzymes. A dose- and time-response for induction of cell death was demonstrated for each compound. A proteomic study showed that inhibitor treatment caused an increase of markers of cell stress, including induction of levels of the autophagy marker, LC-3-II. Levels of this marker protein were highest at cytotoxic inhibitor concentrations, implicating autophagy in the cell death process. An in vivo mouse model showed that one of these inhibitors markedly impaired tumor growth. It is concluded that development of drugs to target these two proteases may provide a novel approach to treating neuroblastoma.

Evaluation and Analysis of Absence of Homozygosity (AOH) Using Chromosome Analysis by Medium Coverage Whole Genome Sequencing (CMA-seq) in Prenatal Diagnosis.

OBJECTIVE: Absence of homozygosity (AOH) is a genetic characteristic known to cause human diseases mainly through autosomal recessive or imprinting mechanisms. The importance and necessity of accurate AOH detection has become more clinically significant in recent years. However, it remains a challenging task for sequencing-based methods thus far. METHODS: In this study, we developed and optimized a new bioinformatic algorithm based on the assessment of minimum sequencing coverage, optimal bin size, the Z-score threshold of four types of allele count and the frequency for accurate genotyping using 28 AOH negative samples, and redefined the AOH detection cutoff value. We showed the performance of chromosome analysis by five-fold coverage whole genome sequencing (CMA-seq) for AOH identification in 27 typical prenatal/postnatal AOH positive samples, which were previously confirmed by chromosomal microarray analysis with single nucleotide polymorphism array (CMA/SNP array). RESULTS: The blinded study indicated that for all three forms of AOH, including whole genomic AOH, single chromosomal AOH and segmental AOH, and all kinds of sample types, including chorionic villus sampling, amniotic fluid, cord blood, peripheral blood and abortive tissue, CMA-seq showed equivalent detection power to that of routine CMA/SNP arrays (750K). The subtle difference between the two methods is that CMA-seq is prone to detect small inconsecutive AOHs, while CMA/SNP array reports it as a whole. CONCLUSION: Based on our newly developed bioinformatic algorithm, it is feasible to detect clinically significant AOH using CMA-seq in prenatal diagnosis.

Enhancement of Output Performance of Triboelectric Nanogenerator by Switchable Stimuli in Metal-Organic Frameworks for Photocatalysis.

Precise control of the structure of crystalline materials is an efficient strategy to manipulate the fundamental performance of solids. In metal-organic framework (MOF) materials, this control can be realized by reversible cation-exchange through chemically driven changes in the crystalline state. Herein, we reported that the reversible structural transformations between an anionic Zn-MOF (1) and a topologically equivalent bimetallic Zn/Co-MOF (2) were accomplished. Both MOFs powders and their hybrid composites were used as positive electrode materials to assemble triboelectric nanogenerators (TENGs). The results demonstrated that the output performance of the Zn/Co-MOF-TENG was effectively improved because the introduction of Co ions makes electron transfer easier. Moreover, the output performance of the TENGs based on MOF@PVDF (PVDF = polyvinylidene fluoride) composite films showed that the Zn/Co-MOF@PVDF-TENG possessed much higher output than these corresponding film-based and MOF-based TENGs. As a practical application, the superior output of Zn/Co-MOF@PVDF-TENG was used to light an ultraviolet lamp plate for the [2 + 2] photochemical cycloaddition of organometallic macrocycles.

Surfactant-assisted assembly of nanoscale zinc coordination compounds to enhance tandem conversion reactions in water.

Precise control over the morphology and size of coordination polymers (CPs) is crucial for extending these inorganic-organic materials to many advanced applications, in particular for heterogeneous catalysis. In this work, two Zn-based CPs, {[Zn3(idbt)2(4,4'-dmbpy)2]·H2O}n (1) and {[Zn3(idbt)2(H2O)3]·H2O}n (2) (H3idbt = 5,5'-(1H-imidazole-4,5-diyl)-bis-(2H-tetrazole), 4,4'-dmbpy = 4,4''-dimethyl-2,2'-bipyridine), were synthesized through solvothermal reactions. The morphologies and particle sizes of 1 and 2 could be controlled from large scale to nanoscale by regulating the amount of poly(vinyl alcohol) (PVA). Furthermore, for the conversion reactions of nitromethylbenzenes into benzoic acids, the catalytic properties of nanoscale 1 and 2 were much more efficient than those of large size of 1 and 2, because of the benefit of readily accessible active sites in the nanoscale sized particles, which provide a tunable and functionalizable platform for the conversion reaction by minimizing the diffusion distance but do little for the selectivity.

Expression and characterization of cathepsin P.

The mouse genome contains a family of clan C1A proteases that appear to be restricted to rodents within Eutherian (placental) mammals. mRNA analysis has shown that these genes are expressed exclusively in placenta. Sequence analysis predicts that the expressed proteins will be functional and consequently it was proposed that this family of proteases may have evolved to perform subspecialized functions of the closely related protease, cathepsin L, that is expressed in placental tissues of all mammalian species. In the present study, it was shown that cathepsin P can be expressed in Pichia pastoris as an inactive zymogen that can be activated with proteinase K, chymotrypsin or pancreatic elastase at neutral pH. Unlike other mammalian cathepsins, cathepsin P could also be autoactivated at neutral pH, but not at acidic pH. The activated enzyme was capable of hydrolysing peptidyl substrates and the protein substrates azocasein and transferrin, with optimal activity at pH 6.5-7.5. Little activity could be detected at pH 5.0 and below. Salts such as Na2SO4 and hyaluronate stimulated the activity of the protease against peptidyl substrates. The properties of cathepsin P appear to be quite distinct from those of cathepsin L, indicating that the duplication that gave rise to cathepsin P has probably not yielded an enzyme that provides a subfunction of cathepsin L in rodents. It seems probable that cathepsin P has evolved to perform a function that is performed by an evolutionarily unrelated protease in other mammalian species.

Stability of furosemide and chlorothiazide stored in syringes.

PURPOSE: The results of a study to determine the stability of solutions of furosemide and chlorothiazide over 96 hours are reported. METHODS: Chlorothiazide and furosemide were diluted in 5% dextrose USP to final concentrations of 10 and 1 mg/mL, respectively, and combined. In addition, sample solutions of chlorothiazide in dextrose, furosemide in dextrose, and dextrose alone were prepared for control purposes. The resulting solutions were analyzed immediately after preparation and 24, 48, 72, and 96 hours later using a liquid chromatography-tandem mass spectroscopy (LC-MS/MS) system with an electrospray ionization source. Mixtures and samples were diluted 10,000-fold prior to LC-MS/MS analysis so that concentrations of both drugs would be within the assay's linear range of detection. RESULTS: LC-MS/MS analysis showed that chlorothiazide typically eluted at 2.6 minutes and furosemide at 4.8 minutes. Each compound was degraded by exposure to strong ultraviolet light in a time-dependent manner. Both unmixed and mixed solutions retained over 90% of the original concentrations of chlorothiazide and furosemide for up to 96 hours. Furosemide and chlorothiazide are commonly used concomitantly to maximize diuresis in pediatric patients; the study findings suggest that solutions of furosemide and chlorothiazide can be combined in the same syringe without loss of stability for up to 96 hours. CONCLUSION: Solutions of chlorothiazide (10 mg/mL) and furosemide (1 mg/mL) stored either separately or together in polypropylene syringes remained stable for up to 96 hours at room temperature and protected from light.

Induction of cell death in neuroblastoma by inhibition of cathepsins B and L.

A specific irreversible inhibitor of both cathepsins B and L, Fmoc-Tyr-Ala-CHN(2) (FYAD) induced apoptosis of neuroblastoma cells but not other tumor cells. Cysteine protease inhibitors that were not efficient inhibitors of both proteases did not cause death of any cell line tested. Apoptosis was preceded by accumulation of large electron dense vesicles and multivesicular bodies in the cytoplasm. Exposure of cells to the cathepsin D inhibitor, pepstatin, failed to rescue cells from FYAD-induced death. These results indicate that inhibition of cathepsins B and L may provide a unique mechanism for selectively inducing death of neuroblastoma with limited toxicity to normal cells and tissues.

Defining the substrate specificity of mouse cathepsin P.

Cathepsin P is a recently discovered placental cysteine protease that is structurally related to the more ubiquitously expressed, broad-specificity enzyme, cathepsin L. We studied the substrate specificity requirements of recombinant mouse cathepsin P using fluorescence resonance energy transfer (FRET) peptides derived from the lead sequence Abz-KLRSSKQ-EDDnp (Abz, ortho-aminobenzoic acid and EDDnp, N-[2,4-dinitrophenyl]ethylenediamine). Systematic modifications were introduced resulting in five series of peptides to map the S(3) to S(2)(') subsites of the enzyme. The results indicate that the subsites S(1), S(2), S(1)('), and S(2)('), present a clear preference for hydrophobic residues. The specificity requirements of the S(2) subsite were found to be more restricted, preferring hydrophobic aliphatic amino acids. The S(3) subsite of the enzyme presents a broad specificity, accepting negatively charged (Glu), positively charged (Lys, Arg), and hydrophobic aliphatic or aromatic residues (Val, Phe). For several substrates, the activity of cathepsin P was markedly regulated by kosmotropic salts, particularly Na(2)SO(4). No significant effect on secondary or tertiary structure could be detected by either circular dichroism or size exclusion chromatography, indicating that the salts most probably disrupt unfavorable ionic interactions between the substrate and enzyme active site. A substrate based upon the preferred P(3) to P(2)(') defined by the screening study, ortho-aminobenzoic-Glu-Ile-Phe-Val-Phe-Lys-Gln-N-(2,4-dinitrophenyl)ethylenediamine (cleaved at the Phe-Val bond) was efficiently hydrolyzed in the absence of high salt. The k(cat)/K(m) for this substrate was almost two orders of magnitude higher than that of the original parent compound. These results show that cathepsin P, in contrast to other mammalian cathepsins, has a restricted catalytic specificity.