Aptamer-modified magnetic SERS substrate for label-based determination of cardiac troponin I

A sensitive label-based SERS strategy composed of magnetic bimetallic nanoparticles Fe₃O₄@Ag@Au, specific aptamer, and Bradford method was developed for the quantitative determination of cardiac troponin I (cTnI) in human serum. The prepared substrate with high magnetic character, signal enhancement, and uniformity exhibited significant Raman response. After the substrate was bound to the aptamer, the target protein cTnI was specifically captured, and it showed the Raman signal when the signal reporter Coomassie Brilliant Blue G-250 (CBBG) was supplied. The Raman signal intensity at 1621 cm^-1 showed a wide linear relationship with the log value of the cTnI concentration in the range 0.01 to 100 ng·mL^-1, and the estimated limit of detection (LOD) was 5.50 pg·mL^-1. The recovery and relative standard deviation (RSD) of the spike experiment in human serum samples were 92-115% and 7.4-12.7%, respectively.

Semi-quantitative, spatially resolved analysis of protein deposit layers on membrane surfaces

Fouling distinctly reduces the filtration performance of membranes. A characterization of the fouling in membranes, however, is difficult due to its spatial distribution. Currently applied methods for deposit layer analysis are rather complex or do not offer a spatial resolution. Knowledge of the spatial distribution, however, could be used to improve the design of membranes, modules, and spacers. Staining with Coomassie Brilliant Blue, related to the staining of PAGE gels, is a simple method to visualize and analyze the deposited proteins semi-quantitatively. We improved an existing staining technique for protein deposits on membranes by adding a calibration for the semi-quantitative analysis and optimizing the sample handling. The method provides a spatially resolved analysis of deposited proteins up to a concentration of 10 g m⁻². Apart from staining, data processing is described in order to generate false colors or topographic images of deposits. Thus, the paper describes a simple method to assess and visualize the influence of module characteristics such as spacer design on the spatially resolved protein fouling of polymeric and ceramic membranes. Therefore, the method can contribute to the improvement of the module design and processing conditions with regard to the filtration performance.

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Visualization of proteinaceous deposits on membranes

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Spatially resolved quantification of proteinaceous deposits

Antidepressant-like Effects Induced by Chronic Blockade of the Purinergic 2X7 Receptor through Inhibition of Non-like Receptor Protein 1 Inflammasome in Chronic Unpredictable Mild Stress Model of Depression in Rats

Objective

Purinergic 2X7 receptor (P2X7R) activation is known to be involved in pathogenesis of depression. Our aims were to investigate P2X7R-activated inflammasome pathways in parallel with induction of depression and to test the antidepressant-like effects of the selective P2X7R antagonist Brilliant Blue G (BBG) in a rat model of chronic unpredictable mild stress (CUMS).

Methods

Male Wistar albino rats were divided into control, CUMS, CUMS+BBG25 (25 mg/kg/day) and CUMS+BBG50 (50 mg/kg/day) groups (n=10 for each group). Various stressors were applied to rats for 6 weeks to establish the CUMS model and daily BBG treatment was started at the end of 3rd week. Sucrose preference test and forced swim test (FST) were performed to assess antidepressant-like effects. Brain samples were obtained for real-time polymerase chain reaction and immunohistochemistry analysis.

Results

In FST, duration of immobility was reduced in the CUMS+BBG50 group. Also, BBG treatment significantly enhanced sucrose preference. While NLRP3 gene expression levels were unchanged in rats exposed to the CUMS protocol, expression levels of other inflammasome pathway factors NLRP1, caspase-1, ASC, NF-κB, IL-1β, IL-6 and P2X7R were increased. BBG treatment reduced expression levels of these factors. Likewise, Iba-1 and GFAP immunoreactivities were enhanced by the CUMS protocol and this action was reversed by BBG treatment.

Conclusion

Chronic administration of BBG in CUMS model results in antidepressant-like activity in a dose dependent manner. Molecular and histological results show that these effects might be at least partially related to the suppression of inflammasome-related neuroinflammatory responses and suggest involvement of NLRP1 in depression.

Curcumin/Turmeric as an Environment-Friendly Protein Gel Stain

Curcumin, the main curcuminoid in food spice turmeric, is insoluble in water at room temperature. We showed that curcumin can be solubilized in water with the application of heat (100 °C). Here we demonstrate that heat-solubilized curcumin can serve as a nontoxic and environment-friendly fluorescent/colorimetric reversible protein stain. Curcumin, the yellow pigment found in the rhizomes of the perennial herb Curcuma longa (turmeric), is insoluble in aqueous solvents. However, heat solubilization in water renders 1.5% of curcumin soluble. Curcumin solubilized by ethanol or alkali is ineffective in staining proteins. Heat-solubilized curry spice turmeric also stains proteins. Staining is achieved in 30 min, with a sensitivity almost equaling that of Coomassie Brilliant Blue (CBB). Destaining is not required and excess curcumin/turmeric can be discarded into the sink. Binding of proteins by silver inhibits curcumin binding, suggesting similarity of protein binding by silver and curcumin. It costs $1.5-2.0 to stain a mini-gel with curcumin, while turmeric costs less than 0.005 cent. CBB staining/destaining costs about two cents. Curcumin/turmeric, thus, can serve as an ideal nontoxic protein stain.

Heat/Pressure Treatment with Detergents Significantly Increases Curcumin Solubility and Stability: Its Use as an Environment-Friendly Protein Gel Stain

Curcumin, the principal curcuminoid in the food spice turmeric, is insoluble in water at room temperature. We have previously solubilized curcumin in water with the application of heat (100 °C) and found that this solubilized curcumin could be used as a gel protein stain. However, heat solubilization in water solubilized only a small fraction of the curcuminoid (1.5%), making it relatively expensive to stain one gel ($1.5-2 per gel). Heat/pressure solubilization (121 °C/15 psi) helps increase the solubility of curcumin in water to only 5%. Therefore, we ventured into increasing curcumin solubility further by using detergents (Tween 20, Tween 80, or Triton X-100) combined with heat/pressure treatment. Curcumin solubilized with Tween 20, Tween 80 or Triton X-100 stained proteins efficiently as before. We could dramatically increase the solubility of curcumin by solubilizing in detergents such that we had to dilute the solubilized curcumin 1:100 with water to stain proteins. However, we had to use the soluble curcumin (extracted with heat/pressure alone) straight without dilution. Thus, the amount of curcumin solubilized with detergents was at least 100-fold, with 0.5% Tween 80 being the most efficient. Staining can be carried out in 30 min, and sensitivity of staining is similar or better than that obtained with Coomassie Brilliant Blue (CBB). It is unnecessary to destain the gel, and excess curcumin can be discarded into the sink, unlike CBB. Curcumin solubilized in Tween 20 has been found to be stable for a period of over 4 years. Therefore, curcumin solubilized in Tween 80 or Triton X-100 can serve as an efficient nontoxic and environment-friendly protein stain. Tween 80 has been used in cough syrups to make a colloidal suspension, and also in foods. Solubilizing curcumin with Tween 80 would be a useful alternative to increase curcumin bioavailability in clinical studies.

Paper Adsorbents Remove Coomassie Blue from Gel Destain and Used Gel Stain in an Environment-Friendly Manner

Coomassie Brilliant Blue (CBB), used to stain protein gels, is known to be toxic. Therefore, laboratories do not discard used CBB into the sink owing to the possibility of it contaminating drinking water supplies. We tested the ability of various paper adsorbents to adsorb CBB released from gels during destaining. The efficiency was as follows-Kimwipes > Teri towels > multifold towels > Whatman numbers 1 and 3 filter papers. Addition of three Kimwipes during destaining helped adsorb the dye released from a CBB-stained mini-gel. Stain removal with Kimwipes helps reduce destain use, organic waste accumulation, enable recycling of nonradioactive destaining solution and is 7.5-fold cheaper than an available method for CBB disposal. Next, we used Kimwipes to deplete the dye from a used CBB staining solution awaiting proper disposal by our Institutional Safety Office. Seventy five Kimwipes successfully helped remove the dye from a 0.05% CBB staining solution in 5-10 min. The blue Kimwipes did not release the CBB stain even when squeezed dry after incubation in various salts, water, or acid solutions for 5 weeks. The CBB removed thus can be simply disposed of as solid waste and will not leach out from solid landfills. Kimwipes, thus, enables CBB disposal in an environmentally friendly manner and allows for recycling of destaining solution.

Coomassie Brilliant Blue Staining of Polyacrylamide Gels

In the past a series of staining procedures for proteins were published. Still, the most commonly used staining dye for proteins is Coomassie Brilliant Blue. The major reason is that Coomassie Brilliant Blue staining is simple, fast, and sensitive. As Coomassie Brilliant Blue is almost insoluble in water a series of procedures including colloidal aqueous procedures has been described.

Application of Heat to Quickly Stain and Destain Proteins Stained with Coomassie Blue

Proteins separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis have been visualized reliably by staining with Coomassie Brilliant Blue. In this chapter, we show that it is possible to drastically reduce protein staining and destaining time, while simultaneously increasing detection sensitivity, with the application of heat. It took 5 min to stain proteins at 55, 62.5, or 70 °C for a 1.5 mm gel, while it took 45, 45, and 20 min respectively for destaining. The time for staining was 1 min for a 0.8 mm gel at 65 °C, 2 min at 60 °C and 5 min at 55 °C. The destaining of proteins separated on a 0.8 mm gel took 8, 15, and 20 min at 65, 60, and 55 °C respectively. Proteins can be stained and destained rapidly with the use of heat, while enhancing detection sensitivity.

Protein Stains and Applications

Staining of proteins separated on gels provides the basis for determination of the critical properties of these biopolymers, such as their molecular weight and/or charge. Detection of proteins on gels and blots require stains. These stains vary in sensitivity, ease of use, color, stability, versatility, and specificity. This review discusses different stains and applications with details on how to use the stains, and advantages and disadvantages of each stain. It also compiles some important points to be considered in imaging and evaluation. Commonly used colorimetric and fluorescent dyes for general protein staining, and stains that detect posttranslational modification-specific detection methods are also discussed.

Silver-Stained Fibrin Zymography: Separation of Proteases and Activity Detection Using a Single Substrate-Containing Gel

Silver-stained fibrin zymography for separation of protease bands and activity detection using a single substrate gel was designed. The method takes advantage of the nano-scale sensitivity of both zymography and silver staining. After sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis (PAGE) in a gel containing fibrin (protease substrate), the gel was incubated in enzyme reaction buffer and the zymogram gel was silver-stained. Bands with protease activity were stained with silver in clear areas where the protein substrate had been degraded. The molecular sizes of proteases were accurately determined.

Destaining of Coomassie Brilliant Blue R-250-stained polyacrylamide gels with fungal laccase

An enzyme-based method for destaining polyacrylamide gels stained with Coomassie Brilliant Blue R-250 is described. Distilled water supplemented with diluted fermentation broth of a laccase-producing white-rot fungus, Cerrena sp., was used for gel destaining, and a clear gel background was obtained in 2 h at 37 °C. Sensitivity of protein detection was 10 ng. The method did not require organic solvents or changing the destaining solution. Due to simultaneous gel destaining and dye decolorization, the colorless destaining solution can be disposed of directly. Laccase destaining of polyacrylamide gels was simple, efficient, and environmentally friendly.

Adsorption of Methylene Blue, Bromophenol Blue, and Coomassie Brilliant Blue by α-chitin nanoparticles

Expelling of dyestuff into water resource system causes major thread to the environment. Adsorption is the cost effective and potential method to remove the dyes from the effluents. Therefore, an attempt was made to study the adsorption of dyestuff (Methylene Blue (MB), Bromophenol Blue (BPB) and Coomassie Brilliant Blue (CBB)) by α-chitin nanoparticles (CNP) prepared from Penaeus monodon (Fabricius, 1798) shell waste. On contrary to the most recognizable adsorption studies using chitin, this is the first study using unique nanoparticles of ⩽50 nm used for the dye adsorption process. The results showed that the adsorption process increased with increase in the concentration of CNP, contact time and temperature with the dyestuff, whereas the adsorption process decreased with increase in the initial dye concentration and strong acidic pH. The results from Fourier transform infrared (FTIR) spectroscopy confirmed that the interaction between dyestuff and CNP involved physical adsorption. The adsorption process obeys Langmuir isotherm (R² values were 0.992, 0.999 and 0.992 for MB, BPB and CBB, and R_L value lies between 0 and 1 for all the three dyes) and pseudo second order kinetics (R² values were 0.996, 0.999 and 0.996 for MB, BPB and CBB) more effectively. The isotherm and kinetic models confirmed that CNP can be used as a suitable adsorbent material for the removal of dyestuff from effluents.

Sonochemical degradation of Coomassie Brilliant Blue: effect of frequency, power density, pH and various additives

Coomassie Brilliant Blue (CBB), discharged mainly from textile industries, is an identified water pollutant. Ultrasound initiated degradation of organic pollutants is one among the promising techniques and forms part of the Advanced Oxidation Processes (AOPs). Ultrasonic degradation of CBB under different experimental conditions has been investigated in the present work. The effect of frequency (200 kHz, 350 kHz, 620 kHz and 1 MHz) and power density (3.5 W mL(-1), 9.8 W mL(-1) and 19.6 W mL(-1)) on the degradation profile was evaluated. The optimum performance was obtained at 350 kHz and 19.6 W mL(-1). Similar to other sonolytic degradation of organic pollutants, maximum degradation of CBB was observed under acidic pH. The degradation profile indicated a pseudo-first order kinetics. The addition of ferrous ion (1×10(-4) M), hydrogen peroxide (1×10(-4) M), and peroxodisulphate (1×10(-4) M) had a positive effect on the degradation efficiency. The influence of certain important NOM like SDS and humic acid on the sonolytic degradation of CBB was also investigated. Both the compounds suppress the degradation efficiency. LC-Q-TOF-MS was used to identify the stable intermediate products. Nearly 13 transformed products were identified during 10min of sonication using the optimized operational parameters. This product profile demonstrated that most of the products are formed mainly by the OH radical attack. On the basis of these results, a degradation mechanism is proposed.

Effects of Brilliant Blue G on Serum Tumor Necrosis Factor-α Levels and Depression-like Behavior in Mice after Lipopolysaccharide Administration

OBJECTIVE

Accumulating evidence suggests that inflammation plays a role in the pathophysiology of major depression. The adenosine triphosphate (ATP)-sensitive P2X7 receptor (P2X7R) plays a crucial role in microglial activation caused by inflammation. The dye brilliant blue G (BBG) is a P2X7R antagonist. This study examined whether BBG shows antidepressant effects in an inflammation-induced model of depression.

METHODS

We examined the effects of BBG (12.5, 25, or 50 mg/kg) on serum tumor necrosis factor-α (TNF-α) levels after administering the bacterial endotoxin lipopolysaccharide (LPS; 0.5 mg/kg) and the effects of BBG (50 mg/kg) on depression-like behavior in the tail-suspension test (TST) and forced swimming test (FST).

RESULTS

Pretreatment with BBG (12.5, 25, or 50 mg/kg) significantly blocked the increase in serum TNF-α levels after a single dose of LPS (0.5 mg/kg). Furthermore, BBG (50 mg/kg) significantly attenuated the increase in immobility time in the TST and FST after LPS (0.5 mg/kg) administration.

CONCLUSION

The results suggest that BBG has anti-inflammatory and antidepressant effects in mice after LPS administration. Therefore, P2X7R antagonists are potential therapeutic drugs for inflammation-related major depression.

Chorein, the protein responsible for chorea-acanthocytosis, interacts with β-adducin and β-actin

Chorea-acanthocytosis (ChAc) is an autosomal, recessive hereditary disease characterized by striatal neurodegeneration and acanthocytosis, and caused by loss of function mutations in the vacuolar protein sorting 13 homolog A (VPS13A) gene. VPS13A encodes chorein whose physiological function at the molecular level is poorly understood. In this study, we show that chorein interacts with β-adducin and β-actin. We first compare protein expression in human erythrocyte membranes using proteomic analysis. Protein levels of β-adducin isoform 1 and β-actin are markedly decreased in erythrocyte membranes from a ChAc patient. Subsequent co-immunoprecipitation (co-IP) and reverse co-IP assays using extracts from chorein-overexpressing human embryonic kidney 293 (HEK293) cells, shows that β-adducin (isoforms 1 and 2) and β-actin interact with chorein. Immunocytochemical analysis using chorein-overexpressing HEK293 cells demonstrates co-localization of chorein with β-adducin and β-actin. In addition, immunoreactivity of β-adducin isoform 1 is significantly decreased in the striatum of gene-targeted ChAc-model mice. Adducin and actin are membrane cytoskeletal proteins, involved in synaptic function. Expression of β-adducin is restricted to the brain and hematopoietic tissues, corresponding to the main pathological lesions of ChAc, and thereby implicating β-adducin and β-actin in ChAc pathogenesis.