Silylated Melamine and Cyanuric Acid as Precursors for Imprinted and Hybrid Silica Materials with Molecular Recognition Properties

Imprinted materials : Monosilylated derivatives of melamine and cyanuric acid are used in the preparation of hybrid silica. The assembly of the melamine and cyanuric acid moieties through molecular recognition properties is the key factor in building a bridged silsesquioxane and an imprinted hybrid silica (see picture).

     

Method development for proteome stabilization in human saliva

Human saliva is a biological fluid with emerging early detection and diagnostic potentials. However, the salivary proteome suffers from rapid degradation and thus compromises its translational and clinical utilities. Therefore, easy, reliable and practical methods are urgently required for the storage of human saliva samples. In this study, saliva samples from healthy subjects were collected and stored at room temperature (RT) and 4 °C for different lengths of time with and without specific protein stabilization treatments. SDS-PAGE was run to compare the protein profiling between samples. Reference proteins, β-actin and interleukin-1 β (IL1β), were chosen to evaluate salivary protein stability. Immunoassay was used for the detection of these target proteins. All data was compared with the positive control that had been kept at −80 °C. The results show that the salivary proteome that has been stored at 4 °C with added protease inhibitors was stable for approximately two weeks without significant degradation. By adding ethanol to the samples, the salivary proteome was stabilized at RT. After optimization, a simple, robust and convenient method is developed for the stabilization of proteins in human saliva that does not affect the downstream translational and clinical applications. The salivary proteome could be stabilized without significant degradation by adding ethanol at RT for about two weeks. This optimized method could greatly accelerate the clinical usage of saliva for future diagnosis.     

A visualization system for observing plastic foaming processes under shear stress

Previous studies offered theories to explain shear-induced bubble nucleation and growth phenomena in plastic foaming processes, but empirical verification was limited due to difficulty in observing these processes in situ under an easily adjustable and uniform shear flow. This study presents a novel visualization system that successfully achieved this goal. The system allows easy control of the critical experimental parameters: applied shear strain, shear strain rate, temperature, pressure, pressure drop rate, plastic material and blowing agent. From a foaming visualization study of polystyrene, it was observed that cell nucleation rate and maximum cell density increased with the applied shear strain, which was due to the decreased local system pressure, detachment and growth of microvoids, and elongation of bubbles. This foaming visualization system provides a direct and effective way to investigate the mechanisms of bubble nucleation and growth under dynamic conditions that simulates industrial plastic foaming processes.     

Synthesis, characterization, photophysics and electrophosphorescent applications of phosphorescent platinum cyclometalated complexes with 9-arylcarbazole moieties

A series of cyclometalating platinum(II) complexes with substituted 9-arylcarbazolyl chromophores have been synthesized and characterized. These complexes are thermally stable and most of them have been characterized by X-ray crystallography. The phosphorescence emissions of the complexes are dominated by ³MLCT excited states. The excited state properties of these complexes can be modulated by varying the electronic characteristics of the cyclometalating ligands via substituent effects, thus allowing the emission to be tuned from bright green to yellow, orange and red light. The correlation between the functional properties of these metallophosphors and the results of density functional theory calculations was made. Because of the propensity of the electron-rich carbazolyl group to facilitate hole injection/transport, the presence of such moiety can increase the highest occupied molecular orbital levels and improve the charge balance in the resulting complexes relative to the parent platinum(II) phosphor with 2-phenylpyridine ligand. The solution-processed electrophosphorescent organic light-emitting diodes doped with these platinum-based phosphors have been fabricated which showed a maximum external quantum efficiency of 2.77% for the best device, corresponding to a power efficiency of 3.48 lm/W and a luminance efficiency of 8.49 cd/A. The present work enables the rational design of platinum-carbazolyl electrophosphors by synthetically tailoring the structure of carbazolylpyridine ring that can permit good color-tuning versatility suitable for multi-color display technology.     

Two-dimensional fluorescence difference gel electrophoresis for comparison of affinity and non-affinity based downstream processing of recombinant monoclonal antibody

Although Staphylococcus Protein A (SpA) affinity chromatography is the state of the art capture step for antibody purification, non-affinity methods are more economical. We used two-dimensional fluorescence difference gel electrophoresis (2-D DIGE) to evaluate the purification of a recombinant IgG₁ antibody from cultured cells, with two different processes: (1) SpA capture followed by cation-exchange chromatography (CEX); and (2) CEX capture, followed by anion exchanger, then hydrophobic interaction chromatography. Efficiencies were similar in sodium dodecylsulphate polyacrylamide gel electrophoresis and size-exclusion chromatography; however, 2-D DIGE revealed higher efficiency with SpA than with CEX capture. Thus, 2-D DIGE is a valuable tool for downstream process development.     

Dual functional polyelectrolyte multilayer coatings for implants: permanent microbicidal base with controlled release of therapeutic agents

Here we present a new bifunctional layer-by-layer (LbL) construct made by combining a permanent microbicidal polyelectrolyte multilayered (PEM) base film with a hydrolytically degradable PEM top film that offers controlled and localized delivery of therapeutics. Two degradable film architectures are presented: (1) bolus release of an antibiotic (gentamicin) to eradicate initial infection at the implant site, or (2) sustained delivery of an anti-inflammatory drug (diclofenac) to cope with inflammation at the site of implantation due to tissue injury. Each degradable film was built on top of a permanent base film that imparts the implantable device surface with microbicidal functionality that prevents the formation of biofilms. Controlled-delivery of gentamicin was demonstrated over hours and that of diclofenac over days. Both drugs retained their efficacy upon release. The permanent microbicidal base film was biocompatible with A549 epithelial cancer cells and MC3T3-E1 osteoprogenitor cells, while also preventing bacteria attachment from turbid media for the entire duration of the two weeks studied. The microbicidal base film retains its functionality after the biodegradable films have completely degraded. The versatility of these PEM films and their ability to prevent biofilm formation make them attractive as coatings for implantable devices.     

Thermo‐ and Acid‐Responsive Photochromic Spironaphthoxazine‐Containing Organogelators

A series of photochromic spironaphthoxazine derivatives has been designed, synthesized, and characterized by using ¹H NMR spectroscopy, FAB mass spectrometry, and elemental analysis. Their photophysical and photochromic behavior have been investigated. Two of the compounds (G¹²‐en‐SA‐SO and G¹⁶‐en‐SA‐SO) have been shown to be capable of forming stable thermoreversible organogels in organic solvents, tested by the “stable‐to‐inversion of a test tube” method. Addition of p‐toluenesulfonic acid was found to induce the formation of stable organogels at concentrations below that of the critical gelation concentration (c.g.c.), with a concomitant change in color from colorless to purple. Transmission electron microscopy and scanning electron microscopy of the xerogels showed typical fibrous structures in the micrometer scale. The activation parameters for the bleaching reaction of G⁸‐en‐SA‐SO in the solution state and G¹⁶‐en‐SA‐SO in the gel state have been determined in ethanol through kinetic studies at various temperatures. The results showed that the rate of the bleaching reaction in the gel state was much slower than that in the solution state.     

Synthesis,Structure and Catalytic Activity of NHC–AgI Carboxylate Complexes

A general synthetic route was used to prepare 15 new N‐heterocyclic carbene (NHC)–Ag^I complexes bearing anionic carboxylate ligands [Ag(NHC)(O₂CR)], including a homologous series of complexes of sterically flexible ITent ligands, which permit a systematic spectroscopic and theoretical study of the structural and electronic features of these compounds. The complexes displayed a significant ligand‐accelerated effect in the intramolecular cyclisation of propargylic amides to oxazolidines. The substrate scope is highly complementary to that previously achieved by NHC–Au and pyridyl–Ag^I complexes.