Ultrasensitive and Multiplexed Protein Imaging with Cleavable Fluorescent Tyramide and Antibody Stripping

Multiplexed single-cell analysis of proteins in their native cellular contexts holds great promise to reveal the composition, interaction and function of the distinct cell types in complex biological systems. However, the existing multiplexed protein imaging technologies are limited by their detection sensitivity or technical demands. To address these issues, here, we develop an ultrasensitive and multiplexed in situ protein profiling approach by reiterative staining with off-the-shelf antibodies and cleavable fluorescent tyramide (CFT). In each cycle of this approach, the protein targets are recognized by antibodies labeled with horseradish peroxidase, which catalyze the covalent deposition of CFT on or close to the protein targets. After imaging, the fluorophores are chemically cleaved, and the antibodies are stripped. Through continuous cycles of staining, imaging, fluorophore cleavage and antibody stripping, a large number of proteins can be quantified in individual cells in situ. Applying this method, we analyzed 20 different proteins in each of ~67,000 cells in a human formalin-fixed paraffin-embedded (FFPE) tonsil tissue. Based on their unique protein expression profiles and microenvironment, these individual cells are partitioned into different cell clusters. We also explored the cell–cell interactions in the tissue by examining which specific cell clusters are selectively associating or avoiding each other.     

Supramolecular Gels Incorporating Cordyline terminalis Leaf Extract as a Polyphenol Release Scaffold for Biomedical Applications

Cordyline terminalis leaf extract (aqCT) possesses abundant polyphenols and other bioactive compounds, which are encapsulated in gelatin–polyethylene glycol–tyramine (GPT)/alpha-cyclodextrin (α-CD) gels to form the additional functional materials for biomedical applications. In this study, the gel compositions are optimized, and the GPT/α-CD ratios equal to or less than one half for solidification are found. The gelation time varies from 40.7 min to 5.0 h depending on the increase in GPT/α-CD ratios and aqCT amount. The aqCT extract disturbs the hydrogen bonding and host–guest inclusion of GPT/α-CD gel networks, postponing the gelation. Scanning electron microscope observation shows that all gels with or without aqCT possess a microarchitecture and porosity. GPT/α-CD/aqCT gels could release polyphenols from 110 to 350 nmol/mL at the first hour and sustainably from 5.5 to 20.2 nmol/mL for the following hours, which is controlled by feeding the aqCT amount and gel properties. GPT/α-CD/aqCT gels achieved significant antioxidant activity through a 100% scavenging DPPH radical. In addition, all gels are non-cytotoxic with a cell viability more than 85%. Especially, the GPT3.75α-CD10.5aqCT gels with aqCT amount of 3.1–12.5 mg/mL immensely enhanced the cell proliferation of GPT3.75α-CD10.5 gel without extract. These results suggest that the inherent bioactivities of aqCT endowed the resulting GPT/α-CD/aqCT gels with effective antioxidant and high biocompatibility, and natural polyphenols sustainably release a unique platform for a drug delivery system or other biomedical applications.     

A refined shear deformation theory for free vibration of functionally graded plates on elastic foundation

A refined shear deformation theory for free vibration of functionally graded plates on elastic foundation is developed. The displacement field is chosen based on assumptions that the in-plane and transverse displacements consist of bending and shear components, and the shear components of in-plane displacements give rise to the parabolic variation of shear strain through the thickness in such a way that shear stresses vanish on the plate surfaces. Therefore, there is no need to use shear correction factor. Material properties of functionally graded plate are assumed to vary according to power law distribution of the volume fraction of the constituents. The elastic foundation is modeled as Pasternak foundation. Equations of motion are derived using Hamilton’s principle. Closed-form solution of rectangular plates is derived, and the obtained results are compared well with three-dimensional elasticity solutions and third-order shear deformation theory solutions. Finally, the influences of power law index, thickness ratio, foundation parameter, and boundary condition on the natural frequency of plates have been investigated.     

Rapid assessment of neoformed compounds in nuts and sesame seeds by front-face fluorescence

The potential of a rapid spectral method, based on front-face fluorescence, to monitor lipid neoformed compounds (NFC) during processing of nuts and sesame seeds was investigated. Fluorescence fingerprints were obtained from front-face fluorescence acquisition directly on crushed nuts and sesame seed samples obtained at different stages of processing. Fluorescence was very sensitive to physicochemical changes induced by the heat process, namely roasting. Parallel factor (PARAFAC) analysis of the fluorescence landscapes revealed four main fluorescence profiles in the nuts, and five in the sesame seeds. These were associated with peptidic tryptophan, tocopherols and process derived products. Various regression models between fluorescence spectra and NFC appearing during the process, carboxymethyllysine (CML) and trans fatty acids (tFA) showed good correlations (R > 0.89) and satisfactory prediction errors (RMSECV < 1.67). When applied to indicators of lipid peroxidation, good regression models were also obtained allowing prediction of the pAV (p-anisidine value) and TBARs (thiobarbituric acid reactive substances): R = 0.73 and 0.96 in nuts and sesame seeds, respectively, with prediction errors lower than 0.78. This study demonstrates the interest of front-face fluorescence as a promising tool for quality control of nuts and seeds roasting.     

Sulfonamide functionalized amino acid-based pH- and temperature-sensitive biodegradable injectable hydrogels: Synthesis,physicochemical characterization and in vivo degradation kinetics

In this research, a novel pH and temperature-sensitive biodegradable oligomer serin-b-poly(lactide)-b-poly (ethylene glycol)-b-poly(lactide)-b- oligomer serin (OS-PLA–PEG–PLA-OS) pentablock copolymer was synthesized with modification of serine to sulfonamide group. The properties of the different pentablock copolymer structures were detail characterized. The copolymer solution easily flowed at high pH and changed to gel state at physiological conditions (37°C, pH 7.4). The sol to gel behavior of these block copolymer solutions were controllable by tuning the length of PEG segment, PLA/PEG block ratio, the molecular weight and the concentration of the pentablock copolymer. The in vivo gelation of the copolymer solution was investigated. The stable gel was formed after injection into the back of the adult male Mus musculus Swiss Albino mice. The degradation process was observed after 6 weeks and showed that the hydrogel depot was bioresorbable without any detection of inflammation sign. The results in this study suggest that the OS-PLA–PEG–PLA-OS pentablock copolymer has the potential application as an injectable delivery vehicle for therapeutic drugs that easily denatured at low-pH condition.     

“Don’t Neglect the User!” – Identifying Types of Human-Chatbot Interactions and their Associated Characteristics

Information Systems Frontiers - Interactions with conversational agents (CAs) become increasingly common in our daily life. While research on human-CA interactions provides insights into the role...     

Kinetics of miniemulsion polymerizations of ethylene glycol dimethacrylate and/or methyl methacrylate

Two types of reactive acrylic microgel particles of methyl methacrylate (MMA)/ethylene glycol dimethacrylate (EGDMA) (66.4/33.6 and 0/100 (mol/mol)) were prepared by miniemulsion polymerization with 2,2′‐azobisisobutyronitrile as the initiator in the temperature range 60–80 °C. Ostwald ripening occurred during the very early stage of polymerization. In addition to the predominant droplet nucleation, homogeneous nucleation was also observed. The polymerization rate for MMA/EGDMA miniemulsion was higher than that for EGDMA miniemulsion. By contrast, comparable apparent limiting conversions were observed for the polymerizations of MMA/EGDMA and EGDMA. The mole fractions of MMA and EGDMA units incorporated into the copolymer product were estimated to be 0.62 and 0.38, respectively, for the polymerization of MMA/EGDMA at 70 °C. The mole fraction of the EGDMA unit containing one ? C?C? within the MMA/EGDMA microgel particle product was estimated to be 0.23, which was comparable to that (0.22) of the EGDMA unit containing one ? C?C? within the EGDMA microgel particle product. © 2015 Society of Chemical Industry     

Local Structure and Chemistry of C‐Doped ZnO@C Core–Shell Nanostructures with Room‐Temperature Ferromagnetism

A superior approach is presented to study quantitatively fine structure of C‐doped ZnO nanostructure using transmission electron microscopy (TEM) from which the role of carbon in ZnO crystal to form ferromagnetism is revealed at the first time. Electron diffraction in TEM shows Wurtzite structure in the nanoparticles with lattice parameters (a = 0.327 ± 0.03 nm and c = 0.529 ± 0.04 nm) slightly different from the original structure. Interestingly, the Zn–C bonding with a bonding length of 2.58 Å is experimentally determined using atomic pair distribution function (PDF) calculated from electron diffraction data. Together with other bondings, such as C–C, Zn–O obtained from the PDF, this demonstrates migration of C atoms into ZnO crystal to substitute O vacancies. This is furthermore visualized by high‐resolution TEM imaging and elemental mapping, and strongly supports the proposal of origin of ferromagnetism in the C‐doped ZnO nanoparticles where the s–p and p–p hybridizations formed by C2p–Zn4s, and O2p–C2p orbitals are believed to cause ferromagnetism.     

Further results on exponential stability of functional differential equations

General non-linear functional differential equations are considered. New explicit criteria for the exponential stability are presented. The stability criteria given in this paper include many existing results as particular cases. In particular, they unify, generalise and improve some ones published recently in [Ngoc, P. H. A. (2012). On exponential stability of non-linear differential systems with time-varying delay. Applied Mathematics Letters, 25(9), 1208–1213 and Ngoc, P. H. A. (2013b). Novel criteria for exponential stability of functional differential equations. Proceedings of the American Mathematical Society, 141(9), 3083–3091]. Two examples are given to show the effectiveness and advantage of the obtained results.