Gene/Protein Disease Symptom Drug Enzyme Compound
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Four series of poly(N-isopropylacrylamide) (PNIPAM) (core)/poly(N-isopropylacrylamide-co-3-acrylamidophenylboronic acid) (P(NIPAM-AAPBA)) (shell) microgels were synthesized by the modification of PNIPAM (core)/poly(N-isopropylacrylamide-co-acrylic acid) (P(NIPAM-AA)) (shell) microgels with 3-aminophenylboronic acid (APBA). Their thermosensitive behaviors were studied by dynamic light scattering. Two or three phase transitions were detected depending on the shell thickness. These transitions were confirmed by the first derivative plot of the turbidity data. The first transition occurring at about 17 degrees C was assigned to that of the P(NIPAM-AAPBA) shell, whereas the second and third ones, which occur at about 22 and 28 degrees C, respectively, were assigned to that of the PNIPAM core. These results indicate that the influences of a shrunk P(NIPAM-AAPBA) shell on the different parts of the PNIPAM core are different. As the outer part, or the "shell" part of the PNIPAM core, directly connects with the P(NIPAM-AAPBA) shell, its phase transition temperature is reduced to a larger degree as compared with that of the inner part, or the "core" part. Glucose-induced swelling was observed for all the microgels, indicating their glucose-sensitivity. However, the degree of glucose-induced swelling is much smaller than that of the pure P(NIPAM-AAPBA) microgels.
ACS Appl Mater Interfaces 2010 Mar
PMID:Thermally induced phase transition of glucose-sensitive core-shell microgels. 2035 78

Mesoporous Ce(OH)CO(3) microspheres with flowerlike three-dimensional (3D) hierarchical structure were successfully synthesized via different hydrothermal systems, including glucose/acrylic acid, fructose/acrylic acid, glucose/propanoic acid, and glucose/n-butylamine systems. After Ce(OH)CO(3) microspheres were calcined, mesoporous CeO(2) microspheres with the same flowerlike morphology as Ce(OH)CO(3) microspheres were obtained. Especially, flowerlike CeO(2) microspheres prepared via the glucose/acrylic acid system are composed of many interconnected mesoporous petal-like nanosheets with thicknesses of 40-60 nm and have high surface area (211 m(2) g(-1)), large pore volume (0.32 cm(3) g(-1)), and narrow pore size distribution ( approximately 3.8 nm in diameter). A possible formation mechanism of Ce(OH)CO(3) microspheres is proposed: the large N-containing organic compounds in situ produced in the above reaction systems played a crucial role in controlling the assembly of Ce(OH)CO(3) building blocks into the flowerlike Ce(OH)CO(3) microspheres. For trichloroethylene combustion, flowerlike CeO(2) microspheres were found to exhibit much higher catalytic activity than general CeO(2) prepared with the conventional methods and the T(10%) and T(90%) were as low as 100 and 204 degrees C, respectively.
ACS Appl Mater Interfaces 2010 Mar
PMID:Hierarchical organization and catalytic activity of high-surface-area mesoporous ceria microspheres prepared via hydrothermal routes. 2035 89

In this paper, we developed a green and facile approach to the synthesis of chemically converted graphene nanosheets (GNS) based on reducing sugars, such as glucose, fructose and sucrose using exfoliated graphite oxide (GO) as precursor. The obtained GNS is characterized with atomic force microscopy, UV-visible absorption spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and so on. The merit of this method is that both the reducing agents themselves and the oxidized products are environmentally friendly. It should be noted that, besides the mild reduction capability to GO, the oxidized products of reducing sugars could also play an important role as a capping reagent in stabilizing as-prepared GNS simultaneously, which exhibited good stability in water. This approach can open up the new possibility for preparing GNS in large-scale production alternatively. Moreover, it is found that GNS-based materials could be of great value for applications in various fields, such as good electrocatalytic activity toward catecholamines (dopamine, epinephrine, and norepinephrine).
ACS Nano 2010 Apr 27
PMID:Reducing sugar: new functional molecules for the green synthesis of graphene nanosheets. 2035 69

Chemical doping with foreign atoms is an effective method to intrinsically modify the properties of host materials. Among them, nitrogen doping plays a critical role in regulating the electronic properties of carbon materials. Recently, graphene, as a true two-dimensional carbon material, has shown fascinating applications in bioelectronics and biosensors. In this paper, we report a facile strategy to prepare N-doped graphene by using nitrogen plasma treatment of graphene synthesized via a chemical method. Meanwhile, a possible schematic diagram has been proposed to detail the structure of N-doped graphene. By controlling the exposure time, the N percentage in host graphene can be regulated, ranging from 0.11 to 1.35%. Moreover, the as-prepared N-doped graphene has displayed high electrocatalytic activity for reduction of hydrogen peroxide and fast direct electron transfer kinetics for glucose oxidase. The N-doped graphene has further been used for glucose biosensing with concentrations as low as 0.01 mM in the presence of interferences.
ACS Nano 2010 Apr 27
PMID:Nitrogen-doped graphene and its application in electrochemical biosensing. 2037 45

To date, limited examples of polyelectrolyte multilayers (PEMs) can be found that truly exploit the power of layer-by-layer nanoassembly to combine multiple functions into a complex multilayer. We demonstrate that PEMs can be designed as optimized coatings for implantable biosensors, exhibiting both diffusion control and protein resistance. PEM coatings comprising strong-weak and weak-weak pairs were evaluated, resulting in decreases in glucose diffusivity up to 5 orders of magnitude compared to water. Addition of poly(ethylene glycol) (PEG)-grafted terminal layers on the base diffusion-controlling multilayers substantially improved resistance to albumin adsorption relative to unmodified PEMs. For transport-controlling films comprising strong-weak polyelectrolyte pairs, the consistent diffusivity was observed even after exposure to protein-containing solutions, indicating minimal effects of biofouling. In contrast, the transport behavior of weak-weak polyelectrolyte pairs was susceptible to alteration by protein exposure, resulting in large variation in diffusivity, even when protein-resistant outer layers were employed.
ACS Appl Mater Interfaces 2010 Apr
PMID:Dual-function nanofilm coatings with diffusion control and protein resistance. 2038 92

In this study, we report a novel approach for glucose-triggered anticancer drug delivery from the self-assembly of neutral poly(vinyl alcohol) (PVA) and chitosan. In the present study, we have fabricated multilayer thin film of PVA-borate and chitosan on colloidal particle (MF particle) and monitored the layer-by-layer growth using Zeta potential measurements. Formation of multilayer membrane on MF particle has been further characterized with transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM). Subsequently, disintegration of multilayer thin film and microcapsules was observed in presence of glucose. We investigated the disassembly of PVA-borate and chitosan self-assembly under CLSM and atomic force microscopy. These results suggest that this multilayer thin film is very efficient for encapsulation and release of DOX molecules above certain concentration of glucose (25 mM). This glucose-sensitive self-assembly is relevant for the application of anticancer therapeutic drug delivery.
ACS Appl Mater Interfaces 2010 May
PMID:Glucose-triggered drug delivery from borate mediated layer-by-layer self-assembly. 2042 53

Acetyl coenzyme A (CoA) is a central metabolite in carbon and energy metabolism and in the biosynthesis of cellular molecules. A source of cytoplasmic acetyl-CoA is essential for the production of fatty acids and sterols and for protein acetylation, including histone acetylation in the nucleus. In Saccharomyces cerevisiae and Candida albicans acetyl-CoA is produced from acetate by cytoplasmic acetyl-CoA synthetase, while in plants and animals acetyl-CoA is derived from citrate via ATP-citrate lyase. In the filamentous ascomycete Aspergillus nidulans, tandem divergently transcribed genes (aclA and aclB) encode the subunits of ATP-citrate lyase, and we have deleted these genes. Growth is greatly diminished on carbon sources that do not result in cytoplasmic acetyl-CoA, such as glucose and proline, while growth is not affected on carbon sources that result in the production of cytoplasmic acetyl-CoA, such as acetate and ethanol. Addition of acetate restores growth on glucose or proline, and this is dependent on facA, which encodes cytoplasmic acetyl-CoA synthetase, but not on the regulatory gene facB. Transcription of aclA and aclB is repressed by growth on acetate or ethanol. Loss of ATP-citrate lyase results in severe developmental effects, with the production of asexual spores (conidia) being greatly reduced and a complete absence of sexual development. This is in contrast to Sordaria macrospora, in which fruiting body formation is initiated but maturation is defective in an ATP-citrate lyase mutant. Addition of acetate does not repair these defects, indicating a specific requirement for high levels of cytoplasmic acetyl-CoA during differentiation. Complementation in heterokaryons between aclA and aclB deletions for all phenotypes indicates that the tandem gene arrangement is not essential.
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PMID:ATP-citrate lyase is required for production of cytosolic acetyl coenzyme A and development in Aspergillus nidulans. 2049 57

This paper describes the use of thread as a matrix for the fabrication of diagnostic assay systems. The kinds of thread used for this study are inexpensive, broadly available, and lightweight; some of them are already familiar materials in healthcare. Fluids wick along these threads by capillary action; no external power source is necessary for pumping. This paper demonstrates three designs for diagnostic assays that use different characteristics of the thread. The first two designs-the "woven array" and the "branching design"-take advantage of the ease with which thread can be woven on a loom to generate fluidic pathways that enable multiple assays to be performed in parallel. The third design-the "sewn array"-takes advantage of the ease with which thread can be sewn through a hydrophobic polymer sheet to incorporate assays into bandages, diapers and similar systems. These designs lead to microfluidic devices that may be useful in performing simple colorimetric assays that require qualitative results. We demonstrate the function of thread-based microfluidic devices in the context of five different colorimetric assays: detection of ketones, nitrite, protein, and glucose in artificial urine, and detection of alkaline phosphatase in artificial plasma.
ACS Appl Mater Interfaces 2010 Jun
PMID:Thread as a matrix for biomedical assays. 2049 13

Harvesting energy from multiple sources available in our personal and daily environments is highly desirable, not only for powering personal electronics, but also for future implantable sensor-transmitter devices for biomedical and healthcare applications. Here we present a hybrid energy scavenging device for potential in vivo applications. The hybrid device consists of a piezoelectric poly(vinylidene fluoride) nanofiber nanogenerator for harvesting mechanical energy, such as from breathing or from the beat of a heart, and a flexible enzymatic biofuel cell for harvesting the biochemical (glucose/O2) energy in biofluid, which are two types of energy available in vivo. The two energy harvesting approaches can work simultaneously or individually, thereby boosting output and lifetime. Using the hybrid device, we demonstrate a "self-powered" nanosystem by powering a ZnO nanowire UV light sensor.
ACS Nano 2010 Jul 27
PMID:Hybrid nanogenerator for concurrently harvesting biomechanical and biochemical energy. 2050 55

Pancreatic beta-cell apoptosis is a critical event during the development of type-1 diabetes. The identification of small molecules capable of preventing cytokine-induced apoptosis could lead to avenues for therapeutic intervention. We developed a set of phenotypic cell-based assays designed to identify such small-molecule suppressors. Rat INS-1E cells were simultaneously treated with a cocktail of inflammatory cytokines and a collection of 2,240 diverse small molecules and screened using an assay for cellular ATP levels. Forty-nine top-scoring compounds included glucocorticoids, several pyrazole derivatives, and known inhibitors of glycogen synthase kinase-3beta. Two compounds were able to increase cellular ATP levels, reduce caspase-3 activity and nitrite production, and increase glucose-stimulated insulin secretion in the presence of cytokines. These results indicate that small molecules identified by this screening approach may protect beta cells from autoimmune attack and may be good candidates for therapeutic intervention in early stages of type-1 diabetes.
ACS Chem Biol 2010 Aug 20
PMID:Small-Molecule Suppressors of Cytokine-Induced beta-Cell Apoptosis. 2055 Jan 76


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