Microwave Induced Synthesis of 3,4-Dihydro-2H-pyran-2-carboxaldehyde: A Versatile Linker for Solid Phase Combinatorial Library

Procedures for the dimerization of acrolein to form 3,4-dihydro-2H-pyran-2-carboxaldehyde by microwave induced synthesis have been developed. Significant rate-enhancement and yield increase were observed. 3,4-Dihydro-2H-pyran-2-carboxaldehyde was obtained in 91% yield under microwave irradiation for 5 minutes instead of 39% yield by reacting at 190 °C for 40 min or at 160 °C for 4 hr.     

Antibacterial single-bead screening

Triazine based antibiotics were prepared by the attachment of cyanuric chloride onto a Marshall-type safety catch linker, followed by successive aromatic nucleophilic substitutions, linker activation and nucleophilic cleavage. High-loading dendrimer beads allowed the release of sufficient amount of compound from a single bead to give clear inhibition.     

2-Bromoethyl glycosides for synthesis of glycoconjugates on solid support

2-Bromoethyl glycosides can easily and in high yields be transformed into sulfones by treatment with a suitable thiol followed by oxidation with mCPBA. The observation that the so formed sulfones were cleaved by treatment with NaOMe/MeOH was used to design a new safety catch linker for synthesis of glycoconjugates on solid support.     

Rheological properties of fresh cement pastes and clinker reactivity

This paper presents research results concerning the influence of clinker reactivity on rheological properties of cement pastes at early stages of hydration (lasting less than one hour). The research was carried out on clinkers synthesized in a laboratory, on non-alkaline cements and cements containing in-built alkalis (sodium, potassium) in the clinker phase.The clinker reactivity was estimated from the flow curves and stress changes in time occurring in clinker pastes while maintaining constant measurement parameters. It was found that the effectiveness of gypsum as a setting controller depends on clinker reactivity. Increased clinker reactivity is accompanied by a decreased consistency of a cement paste.The research results indicate that decreased reactivity of clinkers containing inbuilt alkalis is connected with decreased setting controlling effectiveness of added gypsum. This is manifested by a consistency increase of such system at early stages of hydration.     

Cell‐Mediated Proteolytic Release of Growth Factors from Poly(Ethylene Glycol) Matrices

Engineering in vitro tissue mimetics that resemble the corresponding living tissues requires the 3D arrangement of tissue progenitor cells and their differentiation by localized growth factor (GF) signaling cues. Recent technological advances open a large field of possibilities for the creation of complex GF arrangements. Additionally, cell‐instructive biomaterials, which bind GFs by various mechanisms and release them with different kinetics depending on binding affinity, have become available. This paper describes the development of a matrix metalloproteinase (MMP)‐degradable streptavidin‐based linker module, which allows the release of immobilized GFs from synthetic biomimetic poly(ethylene glycol) hydrogels independently of the hydrogel degradation. The MMP‐sensitive streptavidin linker is shown to efficiently bind biotinylated molecules, and as proof of concept, bone morphogenetic protein‐2 (BMP‐2) delivery via the MMP‐degradable linker is used to induce osteogenic differentiation in C2C12 cells and mesenchymal stem cells. The results show a significantly increased net effect of proteolytically releasable BMP‐2 in comparison to stably immobilized and soluble BMP‐2. This study indicates that a GF delivery system directly responsive to cellular activity can have important implications for the synthesis of tissue mimetics and regenerative medicine, as it can influence the availability, the localization of effects, as well as efficacy of employed GFs.

     

Enhanced two-photon absorption of novel four-branched chromophore via vibronic coupling

A novel four-branched chromophore TOZ-4 with starburst linker was synthesized and showed two-photon absorption cross-section (δ) as large as 5254 GM, which was principally resulted from vibronic coupling enhancement.     

Fabrication of oriented zeolite L monolayer via covalent molecular linkers

For the first time, 1,4-diisocyanatobutane (DICB) was used as the covalent molecular linker in this study to prepare the uniformly oriented zeolite L monolayer with relatively high coverage degree and close packing degree. This could be ascribed to substantial amounts of DICB self-assemble and standing on the substrate surface instead of folding up into a U-shape. This point has been further verified by the quality of oriented zoelite L monolayers obtained from the procedure involving DICB, 1, 4-bis (triethoxysilyl) benzene (BTSEB) and 1,2-bis(trimethoxysilyl)ethane (BTMSE) as covalent molecular linkers.     

Palladium‐Assisted Cleavage of Peptides and Proteins Containing a Backbone with Thiazolidine Linkage

The design and synthesis of biomolecules that are responsive to external stimuli is of great interest in various research areas, such as in the preparation of smart biomaterial and chemical biology. Polypeptide backbone disassembly as a response to a particular stimulus is of interest, as it leads to a complete loss of the protein tertiary structure and, as a result, to a loss of function. In this study, a strategy based on palladium‐assisted efficient cleavage of backbone thiazolidine linkage in peptides and proteins was developed. Using a fluorescence‐based assay, encompassing ubiquitinated peptide with a quenching florescence pair, it was possible to optimize the cleavage step after rapid screening of various conditions, such as the type of metal complexes and reaction additives. The optimized conditions prompted fast cleavage of the thiazolidine linkage. The straightforward introduction of a backbone thiazolidine linkage in peptide and proteins coupled with the chemical methods used offers new opportunities in controlling macromolecule function and might, with the aid of cellular protein delivery methods, be applied in cellular settings.     

In situ organically cross‐linked polymer gel for high‐temperature reservoir conformance control: A review

Polymer gel has been established as water‐blocking agents in oil recovery application. In this practice, a mixture known as gelant is injected into target area and set into a semisolid gel after a certain adequate time. Besides profile modification and water shutoff, the role of the polymer gel in conformance control is to block high permeability regions, before diverting injected water from high permeability to low permeability zones of the reservoir. It is to boost the oil displacement and sweep efficiency. This is the key to improve oil recovery in the heterogeneous oil reservoirs. However, very limited gels are applicable for harsh conditions, especially in high‐temperature reservoirs. Organically cross‐linked polymer is 1 of the materials for conformance control at high‐temperature reservoirs. Many experimental works and field applications have exhibited the potential of this technology. This paper presents a concise review on this polymer gel for conformance control at high‐temperature wells. Firstly, in situ organically cross‐linked polymer gel has been introduced, and the reason of the use over other types of polymer gels is summarized. The early studies of organically cross‐linked gel systems are also discussed, followed by the chemistry and the gelation mechanisms. An extensive review on factors that affect gelation kinetics and field applications is also discussed in some detail.     

Water solubilization of xanthene dyes by post-synthetic sulfonation in organic media

Highly water-soluble fluorescent fluorescein and rhodamine dyes were synthesized through amidification of their carboxylic acid functionality with original di- or tri-sulfonated amino linkers derived from taurine or α-sulfo-β-alanine. This post-synthetic derivatization was performed in organic media both to minimize the premature hydrolysis and to suppress the precipitation of the involved active ester of fluorophore, frequently encountered using standard Schotten-Baumann conditions.