Towards combinatorial mixing devices without any pumps by open-capillary channels: fundamentals and applications.

In chemistry, biology, medical sciences and pharmaceutical industries, many reactions have to be checked by transporting and mixing expensive liquids. For such purposes, microfluidics systems consisting of closed channels with external pumps have been useful. However, the usage has been limited because of high fabrication cost and need for a fixed setup. Here, we show that open-capillary channels, which can be fabricated outside a clean room on durable substrates and are washable and reusable, are considerably promising for micro-devices that function without pumps, as a result of detailed studies on the imbibition of open micro-channels. We find that the statics and dynamics of the imbibition follow simple scaling laws in a wide and practical range; although a precursor film obeying a universal dynamics appears in the vertical imbibition, it disappears in the horizontal mode to make the design of complex micro-channel geometry feasible. We fabricate micro open-channel devices without any pumps to express the green fluorescent protein (GFP) by transporting highly viscous solutions and to accomplish simultaneous chemical reactions for the Bromothymol blue (BTB) solution. We envision that open-capillary devices will become a simple and low-cost option to achieve microfluidic devices that are usable in small clinics and field studies.

Gelatin-alginate gels and their enzymatic modifications: controlling the delivery of small molecules.

The release of molecules entrapped within biogels is dictated by diffusion laws. Innovative biogel architectures are conceived and tested to control small molecule delivery from gelatin gels. The ionic interactions modulate the release of small molecules. Alginate is then added to gelatin gels and further hydrolyzed; the influence of viscosity is discussed. Next, various mixed gels are compared, such as a gelatin-alginate IPN and the original architecture of an alginate gel entrapped in a gelatin gel with or without a polysaccharidase. The relative influence of ionic interactions and diffusional constraints on the delivery of small charged molecules is explored, and a solution for controlling diffusion is proposed for any situation.

Triphenylmethane dyes, an alternative for mediated electronic transfer systems in glucose oxidase biofuel cells.

The bioelectrochemical behavior of three triphenylmethane (TPM) dyes commonly used as pH indicators, and their application in mediated electron transfer systems for glucose oxidase bioanodes in biofuel cells was investigated. Bromophenol Blue, Bromothymol Blue, Bromocresol Green were compared bioelectrochemically against two widely used mediators, benzoquinone and ferrocene carboxy aldehyde. Biochemical studies were performed in terms of enzymatic oxidation, enzyme affinity, catalytic efficiency and co-factor regeneration. The different features of the TPM dyes as mediators are determined by the characteristics in the oxidation/reduction processes studied electrochemically. The reversibility of the oxidation/reduction processes was also established through the dependence of the voltammetric peaks with the sweep rates. All three dyes showed good performances compared to the FA and BQ when evaluated in a half enzymatic fuel cell. Potentiodynamic and power response experiments showed maxima power densities of 32.8 µW cm(-2) for ferrocene carboxy aldehyde followed by similar values obtained for TPM dyes around 30 µW cm(-2) using glucose and mediator concentrations of 10 mmol L(-1) and 1.0 mmol L(-1), respectively. Since no mediator consumption was observed during the bioelectrochemical process, and also good redox re-cycled processes were achieved, the use of triphenylmethane dyes is considered to be promising compared to other mediated systems used with glucose oxidase bioanodes and/or biofuel cells.

Identification of Cryptococcus gattii by use of L-canavanine glycine bromothymol blue medium and DNA sequencing.

Cryptococcus neoformans and Cryptococcus gattii are closely related pathogenic fungi. Cryptococcus neoformans is ecologically widespread and affects primarily immunocompromised patients, while C. gattii is traditionally found in tropical climates and has been reported to cause disease in immunocompetent patients. l-Canavanine glycine bromothymol blue (CGB) agar can be used to differentiate C. neoformans and C. gattii, but there are few reports of its performance in routine clinical practice. Growth of C. gattii on CGB agar produces a blue color, indicating the assimilation of glycine, while C. neoformans fails to cause a color change. Using reference and clinical strains, we evaluated the ability of CGB agar and D2 large ribosomal subunit DNA sequencing (D2 LSU) to differentiate C. neoformans and C. gattii. One hundred two yeast isolates were screened for urease activity, melanin production, and glycine assimilation on CGB agar as well as by D2 sequencing. Seventeen of 17 (100%) C. gattii isolates were CGB positive, and 54 of 54 C. neoformans isolates were CGB negative. Several yeast isolates other than the C. gattii isolates were CGB agar positive, indicating that CGB agar cannot be used alone for identification of C. gattii. D2 correctly identified and differentiated all C. gattii and C. neoformans isolates. This study demonstrates that the use of CGB agar, in conjunction with urea hydrolysis and Niger seed agar, or D2 LSU sequencing can be reliably used in the clinical laboratory to distinguish C. gattii from C. neoformans. We describe how CGB agar and D2 sequencing have been incorporated into the yeast identification algorithm in our laboratory.

Natural occurrence and growth reaction on canavanine-glycine-bromothymol blue agar of non-neoformans Cryptococcus spp. in Malaysia.

Cryptococcus albidus and C. laurentii were the predominant non-neoformans cryptococci isolated during an environmental sampling study for C. gattii at Klang Valley, Malaysia. Cryptococcus gattii was not isolated from any of the environmental samples. Cryptococcus albidus and C. laurentii were isolated mainly from vegetative samples of Eucalyptus trees and bird droppings. Upon testing on canavanine-glycine-bromothymol blue (CGB) agar, all the C. albidus isolates remained unchanged. Interestingly, a total of 29 (76.3%) C. laurentii isolates formed blue colours on the CGB agar. Sequence analysis of ITS1-5.8rDNA-ITS2 gene sequences (468 bp) of four CGB-blue C. laurentii isolates demonstrated the closest match (99%) with that of C. laurentii CBS 7140. This study demonstrated the diverse environmental niche of C. albidus and C. laurentii in Malaysia.

A sensor to detect the early stages in the development of crystalline Proteus mirabilis biofilm on indwelling bladder catheters.

A simple sensor has been developed to detect the early stages of urinary catheter encrustation and avoid the clinical crises induced by catheter blockage. In laboratory models of colonization by Proteus mirabilis, the sensor signaled encrustation at an average time of 43 h before catheters were blocked with crystalline biofilm.

Simple colorimetric method for detecting degenerate strains of the cultivated basidiomycete Flammulina velutipes (Enokitake).

Degeneration of cultivated strains of Flammulina velutipes is a serious problem. We developed a simple colorimetric method to detect degenerate strains by using a liquid medium supplemented with bromothymol blue and lactose. The ability of a strain to develop normal mushrooms could be determined by the color of the medium.

[Effect of cryoprotectors on binding of bromthymol blue by bovine methemoglobin]. / Vliianie krioprotektorov na sviazyvanie bromtimolovogo sinego metgemoglobinom byka.

Spectrophotometric method was used for study the binding of bromthymol blue dye (BTB) with bovine methemoglobin in 15% solutions of ethanol, glycerol and polyethylene glycol with molecular mass of 1.5 kDa (PEG-1500). It was shown, that adsorption of BTB by methemoglobin decreased in the sequence: glycerol > ethanol > PEG-1500. It is supposed that adsorption of the alcohols on the BTS sites of binding on methemolglobin led to the decrease of the amount of binding sites accessible for the dye.

[Study of bromthymol blue binding with plasma membranes]. / Issledovanie sviazyvaniia bromtimolovogo sinego s plazmaticheskimi membranami.

It has been established that sorption of bromthymol blue by membranes is due to interaction with integral proteins. The value of the bond is ascribed both to the structural state and electrochemical property of membranes.

An oxygenation-linked dye binding to Limulus polyphemus hemocyanin.

The reaction of Limulus polyphemus hemocyanin with a dye, bromthymol blue, was examined by equilibrium dialysis, spectrophotometric titration and stopped-flow methods. Oxy-hemocyanin contained one binding site per hexamer unit. The dye binding was linked to oxygenation, and the affinity of the dye for the oxy form was about 10 times as high as that for the deoxy form. Conversely, the dye increased the O2 affinity of hemocyanin. Hemocyanin showed a simple hyperbolic binding curve in the bromthymol blue titration, whereas the time course of the reaction was generally biphasic. It was inferred from the kinetic analyses that the reaction proceeds in two steps. The first bimolecular step is characterized by an increase in the apparent pKa of the bound dye, while the second unimolecular step by a red shift of the absorption band of the unionized dye. The dye binding to partially oxygenated hemocyanin was examined spectrophotometrically; the fractional change in the binding was found to be ahead of the increase in the average degree of O2 saturation. It was concluded that the structural changes in hemocyanin which lead to the increased dye affinity take place at an early stage of the ligand binding sequence.

[Sorption of sulfophthaleinic dyes by the brain synaptosomes of rats deprived of parodoxical sleep]. / Sorbtsiia sul'foftaleinovykh krasitelei sinaptosomami golovnogo mozga krys, lishennykh paradoksal'noi fazy sna.

The influence of paradoxical sleep deprivation on sorption of bromphenol blue, bromcresol green and bromthymol blue by rat's brain synaptosomes was studied. Effect of sleep disturbance (increase in the number of dye bindings) was shown to augment with the increase in hydrophobicity of the sulfophtaleinic dye.

[Influence of laser radiation on the binding of bromthymol blue by microsomes]. / Vliianie lazernogo izlucheniia na sviazyvanie bromtimolovogo sinego mikrosomami.

It was stated that radiation of liver microsomes with helium--neon laser (lambda = 6328 A, the power of radiation 25 mvt) during 30 minutes leads to a decrease of the amount of sorption centres from 25.6 to 10.2 mol/g of protein and a change of delta F degree from -7.0 to -4.1 kkal/mol for bromthymol dark blue.

Renal handling of phenol red. IV. Tubular localization in rabbit and rat kidney in vivo.

In the rabbit kidney accumulation of phenol red in cortex tissue is directly related to phenol red excretion. In histological preparations of rabbit cortex the major part of phenol red is localized to the pars recta of proximal tubules at low plasma concentrations of dye. The extra uptake of dye by the pars recta is abolished by administration of a high dose of probenecid and also by high plasma dye concentrations, when dye secretion is low relative to tubular reabsorption. Tissue accumulation of phenol red in the rat exhibits features similar to those in the rabbit. However, extra dye uptake in the pars recta is maintained after administration of probenecid, and disappears after intravenous injection of phenol red during ureteral occlusion to impede access of dye from tubule fluid to the luminal membrane. It is concluded that in the rabbit phenol red uptake by the pars recta probably is due to tubular secretion across the peritubular membrane, whereas in the rat extra uptake of dye by this segment is consistent with uptake at the luminal cell membrane.