Dehydration of an ethanol/water azeotrope through alginate-DNA membranes cross-linked with metal ions by pervaporation.

To obtain high dehydration membranes for an ethanol/water azeotrope, dried blend membranes prepared from mixtures of sodium alginate (Alg-Na) and sodium deoxyribonucleate (DNA-Na) were cross-linked by immersing in a methanol solution of CaCl2 or MaCl2. In the dehydration of an ethanol/water azeotropic mixture by pervaporation, the effects of immersion time in methanol solution of CaCl2 or MaCl2 on the permeation rate and water/ethanol selectivity through Alg-DNA/Ca(2+) and Alg-DNA/Mg(2+) cross-linked membranes were investigated. Alg-DNA/Mg(2+) cross-linked membrane immersed for 12h in methanol solution of MaCl2 exhibited the highest water/ethanol selectivity.

Pervaporative dehydration characteristics of an ethanol/water azeotrope through various chitosan membranes.

The permeation and separation characteristics of an ethanol/water azeotrope through chitosan membranes of different molecular weights and degrees of deacetylation during pervaporation were investigated. The normalized permeation rate decreased with increasing molecular weight up to 90 kDa, but at over 90 kDa, the rate increased. On the other hand, the water/ethanol selectivity increased with increasing molecular weight up to 90 kDa but decreased at over 90 kDa.

Preparation of molecule-responsive microsized hydrogels via photopolymerization for smart microchannel microvalves.

Microdevices designed for practical environmental pollution monitoring need to detect specific pollutants such as dioxins. Bisphenol A (BPA) has been widely used as a monomer for the synthesis of polycarbonate and epoxy resins. However, the recent discovery of its high potential ability to disrupt human endocrine systems has made the development of smart systems and microdevices for its detection and removal necessary.

Target molecule-responsive hydrogels designed via molecular imprinting using bisphenol A as a template.

Target molecule-responsive hydrogels with β-cyclodextrin (β-CD) were prepared via molecular imprinting using bisphenol A (BPA) as a template. BPA-imprinted hydrogels showed greater shrinkage than non-imprinted hydrogels because CD ligands arranged at suitable positions formed CD-BPA-CD complexes that acted as crosslinks.

Responsive behavior of tumor-marker-imprinted hydrogels using macromolecular cross-linkers.

Tumor-marker-imprinted hydrogels having lectin and antibody molecules as ligands for a tumor-specific marker glycoprotein were strategically prepared by biomolecular imprinting using minute amounts of low-molecular-weight or high-molecular-weight cross-linkers. The tumor-marker-imprinted hydrogels shrank gradually in response to a target glycoprotein, because their apparent cross-linking density increased owing to simultaneous complex formation of lectin and antibody ligands with a target glycoprotein after their ligands dynamically recognized the glycoprotein. The swelling ratio of the tumor-marker-imprinted hydrogel using high-molecular-weight cross-linker with an optimal chain length decreased more drastically than that using a low-molecular-weight cross-linker, but the hydrogel using the cross-linker with a chain that was too long did not exhibit tumor-marker responsive behavior.

Synthesis of glucose-responsive bioconjugated gel particles using surfactant-free emulsion polymerization.

Bioconjugated gel particles that have complexes composed of lectin concanavalin A (ConA) and 2-glucosyloxyethyl methacrylate (GEMA) were synthesized by the surfactant-free emulsion copolymerization of N,N-diethylaminoethyl methacrylate (DEAEMA), poly(ethylene glycol) dimethacrylate (PEGDMA), GEMA, and modified-ConA with polymerizable groups. The resultant gel particles having GEMA-ConA complexes (GEMA-ConA gel particles) were colloidally stable in a phosphate buffer solution and had a diameter of approximately 750nm. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) measurements implied that GEMA-ConA gel particles have core-shell structures consisting of a hydrophobic core of DEAEMA and a hydrophilic shell of GEMA and PEGDMA containing ConA.

Tumor marker-responsive behavior of gels prepared by biomolecular imprinting.

We report dynamic glycoprotein recognition of gels prepared by biomolecular imprinting using lectin and antibody molecules as ligands for tumor-specific marker glycoproteins. The glycoprotein-imprinted gels prepared with minute amounts of cross-linkers could dynamically recognize tumor-specific marker glycoproteins by lectin and antibody ligands and induce volume changes according to the glycoprotein concentration. The glycoprotein-imprinted gel shrank in response to a target glycoprotein but nonimprinted gel swelled a little.

Performance of butyrylcellulose membranes for benzene/cyclohexane mixtures containing a low benzene concentration by pervaporation.

Butyrylcellulose (BuCell) with different degrees of butyrylation was synthesized as a membrane material for the separation of benzene/cyclohexane (Bz/Chx) mixtures. A BuCell membrane with a degree of butyrylation of 2.3 showed high benzene/cyclohexane selectivity for Bz/Chx mixtures by pervaporation.

Dehydration of an ethanol/water azeotrope by novel organic-inorganic hybrid membranes based on quaternized chitosan and tetraethoxysilane.

To control swelling of quaternized chitosan (q-Chito) membranes, mixtures of q-Chito as an organic component and tetraethoxysilane (TEOS) as an inorganic component were prepared using the sol-gel reaction, and novel q-Chito/TEOS hybrid membranes were formed. In the separation of an ethanol/water azeotrope by pervaporation, the effect of TEOS content on the water/ethanol selectivity of q-Chito/TEOS hybrid membranes was investigated. Hybrid membranes containing up to 45 mol % TEOS exhibited higher water/ethanol selectivity than the q-Chito membrane.

Dehydration from alcohols by polyion complex cross-linked chitosan composite membranes during evapomeation.

This study describes the dehydration of an ethanol/water azeotrope during evapomeation using polyion complex cross-linked chitosan composite (q-Chito-PEO acid polyion complex/PES composite) membranes, constructed from quaternized chitosan (q-Chito) and poly(ethylene oxydiglycolic acid) (PEO acid) on a porous poly(ether sulfone) (PES) support. Both the q-Chito/PES composite and the q-Chito-PEO acid polyion complex/PES composite membranes showed high water permselectivity for an ethanol/water azeotrope. Both the permeation rate and the water permselectivity of the q-Chito/PES composite membranes were enhanced by increasing the degree of quaternization of the chitosan molecule because the affinity of the q-Chito/PES composite membranes for water was increased by introducing a quaternized ammonium group into the chitosan molecule.

Biomolecule-sensitive hydrogels.

Stimuli-sensitive hydrogels have attracted considerable attention as intelligent materials in the biochemical and biomedical fields, since they can sense environmental changes and induce structural changes by themselves. In particular, biomolecule-sensitive hydrogels that undergo swelling changes in response to specific biomolecules have become increasingly important because of their potential applications in the development of biomaterials and drug delivery systems. This article provides an overview of the important and historical research regarding the synthesis and applications of glucose-sensitive hydrogels which exhibit swelling changes in response to glucose concentration.