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Diabetes mellitus is one of the most common chronic diseases worldwide. Generally, the levels of fasting or postprandial blood glucose and other biomarkers, such as glycated albumin, glycated hemoglobin, and 1,5-anhydroglucitol, are used to diagnose or monitor diabetes progression. In the present study, we developed a sensor to simultaneously detect the glucose levels and glycation ratios of human serum albumin using a lateral flow assay. Based on the specific enzymatic reactions and immunoassays, a spiked glucose solution, total human serum albumin, and glycated albumin were measured simultaneously. To test the performance of the developed sensor, clinical serum samples from healthy subjects and patients with diabetes were analyzed. The glucose level and glycation ratios of the clinical samples were determined with reasonable correlation. The R-squared values of glucose level and glycation ratio measurements were 0.932 and 0.930, respectively. The average detection recoveries of the sensor were 85.80% for glucose and 98.32% for the glycation ratio. The glucose level and glycation ratio in our results were crosschecked with reference diagnostic values of diabetes. Based on the outcomes of the present study, we propose that this novel platform can be utilized for the simultaneous detection of glucose and glycation ratios to diagnose and monitor diabetes mellitus.

This communication describes the rational design of a transparent paper-based chemosensing platform for multi-target detection by wavelength-dependent absorbance/transmittance. The platform was successfully applied in the examination of bovine serum albumin (BSA) and cholesterol in serum with a low detection limit of 0.1 μM and 0.1 mM, respectively. With low cost and high sensitivity, the paper-based platform shows great promise for multiplexed bioassays.

The aim of this study was to evaluate the impact of creatine supplementation (CS) on renal function in young, healthy, and active subjects. We used a randomized, double-blind, placebo-controlled clinical trial as the study design. Thirty-six healthy male university students were recruited and divided into three groups: group placebo, group G3 (3 g/day of CS), and group G5 (5 g/day of CS). To assess renal function, new kidney biomarkers, kidney injury molecule-1 (KIM-1) and monocyte chemoattractant protein-1 (MCP-1), were quantified. Serum albumin, serum creatinine, serum urea, estimated glomerular filtration rate (eGFR), proteinuria, and albuminuria were also measured. All groups were evaluated at two times: prior CS or placebo (pre) and after 35 days on CS or placebo (post). After 35 days of intervention, all characteristics were maintained without significant difference (P > 0.05) between the groups, including serum creatinine, eGFR, and more sensitive kidney biomarker concentrations (KIM-1 and MCP-1). The paired analysis showed that the supplemented groups (G3 and 5G) had increased serum creatinine and decreased eGFR levels (P

Point-of-care testing (POCT) devices represent a growing field that aims to develop low-cost, rapid, sensitive diagnostic testing platforms that are portable and self-contained. Surface-enhanced Raman spectroscopy (SERS) is an approach has shown high potential in POCT technology. However, the specificity or ability to uniquely detect a desired biomarker in complex biological samples is a key factor for translating SERS technologies to POCT. Herein, we fabricated cellulose SERS strips (CS) decorated with novel plasmonic nanoparticles, termed graphene-isolated-Au-nanocrystals (GIANs), for the portable detection of complex biological samples. This CS@GIANs SERS strip was used to detect free bilirubin (BR) in the blood of newborns, a biomarker of jaundice, without sample labeling or prepreparation. CS@GIANs showed superior affinity to hydrophobic BR molecules compared to typical SERS substrate, which reduced the steric hindrance effect from the nonspecific binding of BR with serum albumin in blood and improved sensitivity. Meanwhile, with the separation property of cellulose chromatography papers, CS@GIANs showed superior anti-interference to other biomolecules that had been previously adsorbed on the SERS strip. Moreover, the SERS signal from the graphitic shell of GIANs could be used as a stable internal calibration standard, which improved the reproducibility and accuracy of Raman analysis. Such a cellulose SERS strip holds high potential for enhancing current efforts in the development of rapid and low-cost point-of-care diagnostic testing.

A novel paper-based analytical device (PAD) was fabricated and developed for the simple and rapid determination of the albumin to creatinine ratio (ACR) in urine samples. The detection was based on a colorimetric reaction using bromocresol green (BG) in a phosphate buffer (PB) at pH 4 for the determination of albumin (AL) and creatinine (CR). BG changes color from greenish-yellow to bluish-green in the presence of AL and/or CR. Picric acid (PA) in 0.25 M NaOH was used to detect CR, and PA changes color from yellow to orange. Under the optimal conditions, the working range was 10 to 350 mg dL-1 with a detection limit of 7.1 and 5.4 mg dL-1 for AL + CR and CR detection, respectively. The repeatability was evaluated, and the %RSD value was less than 8.23 (n = 10). The ACR was obtained by calculating the AL and CR colorimetric results. Finally, the proposed devices were applied to the determination of AL, CR, and ACR in urine samples. The results obtained by the developed PADs were in good agreement with the standard method and demonstrated the method could reliably measure AL, CR, and ACR. The proposed method provides a low-cost, simple, sensitive, and promising tool for diagnostic identification assay for chronic kidney disease (CKD).

Bovine serum albumin (BSA) was added to filter paper during the hydrolysis of cellulase. Adding BSA before the addition of the cellulase enhances enzyme activity in the solution, thereby increasing the conversion rate of cellulose. After 48 h of BSA treatment, the BSA adsorption quantities are 3.3, 4.6, 7.8, 17.2, and 28.3 mg/g substrate, each with different initial BSA concentration treatments at 50 °C; in addition, more cellulase was adsorbed onto the filter paper at 50 °C compared with 35 °C. After 48 h of hydrolysis, the free-enzyme activity could not be measured without the BSA treatment, whereas the remaining activity of the filter paper activity was approximately 41 % when treated with 1.0 mg/mL BSA. Even after 96 h of hydrolysis, 25 % still remained. Meanwhile, after 48 h of incubation without substrate, the remaining enzyme activities were increased 20.7 % (from 43.7 to 52.7 %) and 94.8 % (from 23.3 to 45.5 %) at 35 and 50 °C, respectively. Moreover, the effect of the BSA was more obvious at 35 °C compared with 50 °C. When using 15 filter paper cellulase units per gram substrate cellulase loading at 50 °C, the cellulose conversion was increased from 75 % (without BSA treatment) to ≥90 % when using BSA dosages between 0.1 and 1.5 mg/mL. Overall, these results suggest that there are promising strategies for BSA treatment in the reduction of enzyme requirements during the hydrolysis of cellulose.

Microfluidic paper-based analytical devices (μPADs) for molecular detection have great potential in the field of point-of-care diagnostics. Currently, a critical problem being faced by μPADs is improving their detection sensitivity. Various preconcentration processes have been developed, but they still have complicated structures and fabrication processes to integrate into μPADs. To address this issue, we have developed a novel paper-based preconcentrator utilizing ion concentration polarization (ICP) with minimal addition on lateral-flow paper. The cation selective membrane (i.e., Nafion) is patterned on adhesive tape, and this tape is then attached to paper-based channels. When an electric field is applied across the Nafion, ICP is initiated to preconcentrate the biomolecules in the paper channel. Departing from previous paper-based preconcentrators, we maintain steady lateral fluid flow with the separated Nafion layer; as a result, fluorescent dyes and proteins (FITC–albumin and bovine serum albumin) are continuously delivered to the preconcentration zone, achieving high preconcentration performance up to 1000-fold. In addition, we demonstrate that the Nafion-patterned tape can be integrated with various geometries (multiplexed preconcentrator) and platforms (string and polymer microfluidic channel). This work would facilitate integration of various ICP devices, including preconcentrators, pH/concentration modulators, and micro mixers, with steady lateral flows in paper-based platforms.

In this work, bovine serum albumin (BSA)-Au nanoclusters were used to coat a paper-based microfluidic device. This device acted as a Cu(2+) biosensor that showed fluorescence quenching on detection of copper ions. The detection limit of this sensor could be adjusted by altering the water absorbing capacity of the device. Qualitative and semi-quantitative results could be obtained visually without the aid of any advanced instruments. This sensor could test Cu(2+) rapidly with high specificity and sensitivity, which would be useful for point-of-care testing (POCT).

Background Rifampicin or rifampin (R) is a common drug used to treat inactive meningitis, cholestatic pruritus and tuberculosis (TB), and it is generally prescribed for long-term administration under regulated dosages. Constant monitoring of rifampicin is important for controlling the side effects and preventing overdose caused by chronic medication. In this study, we present an easy to use, effective and less costly method for detecting residual rifampicin in urine samples using protein (bovine serum albumin, BSA)-stabilized gold nanoclusters (BSA-Au NCs) adsorbed on a paper substrate in which the concentration of rifampicin in urine can be detected via fluorescence quenching. The intensity of the colorimetric assay performed on the paper-based platforms can be easily captured using a digital camera and subsequently analyzed. Results The decreased fluorescence intensity of BSA-Au NCs in the presence of rifampicin allows for the sensitive detection of rifampicin in a range from 0.5 to 823 µg/mL. The detection limit for rifampicin was measured as 70 ng/mL. The BSA-Au NCs were immobilized on a wax-printed paper-based platform and used to conduct real-time monitoring of rifampicin in urine. Conclusion We have developed a robust, cost-effective, and portable point-of-care medical diagnostic platform for the detection of rifampicin in urine based on the ability of rifampicin to quench the fluorescence of immobilized BSA-Au NCs on wax-printed papers. The paper-based assay can be further used for the detection of other specific analytes via surface modification of the BSA in BSA-Au NCs and offers a useful tool for monitoring other diseases. Electronic supplementary material The online version of this article (doi:10.1186/s12951-015-0105-5) contains supplementary material, which is available to authorized users.

Objective: Immunological mechanisms may be part of the pathophysiological mechanisms in frontotemporal dementia (FTD), but hitherto only vague evidence of such mechanisms has been presented. The aim of this study was to compare the cerebrospinal fluid (CSF) levels of the pro-inflammatory cytokines interleukin (IL)-1s and tumour necrosis factor (TNF)-α, and the anti-inflammatory cytokine transforming growth factor (TGF)-s in patients with FTD and normal controls. Furthermore, serum levels of TNF-α, TGF-s, and IL-1s were measured in FTD patients. Methods: The CSF levels of IL-1s, TNFα, and TGF-s were measured using ELISA in 19 patients with FTD and 24 sex and age matched healthy controls. Results: The CSF levels of TNF-α (FTD 0.6 pg/mL (median: lower, upper quartile 0.3, 0.7); controls: 0.0 pg/mL (0.0, 0.0); p = 0.008) and TGF-s (FTD 266 pg/mL (157, 371), controls: 147 pg/mL (119, 156); p = 0.0001) were significantly increased in FTD patients compared with controls. No correlations were found between CSF and serum levels of the cytokines. In the controls, but not in the FTD patients, a positive correlation was found between the CSF levels of TGF-s and age (r = 0.42, p

The possibility to use polymer carrier for transport of retinol (R) and the peptide enhancing regeneration of head section of Hydra (PH) has been studied. Efflux of R occurs both through intact polymer and through pores formed in the polymer by albumin, whereas PH is not able to penetrate the polymer and its rate of efflux is determined by the amount of albumin added. The efflux of both R and PH changes with time in a stepwise manner. The total yield of R and PH after 37 days varied in the range of 17 to 40% and 1 to 95%, respectively, in different experimental conditions.

Utilizing the principles of counterimmunoelectrophoresis, a technique was devised to immunologically identify non-denatured protein antigens resolved by polyacrylamide gel electrophoresis. Proteins were electrophoretically transferred from polyacrylamide gel to antibody-containing agarose gel in a commercially available blotting apparatus. Detection of the antigen/antibody complex by Coomassie blue staining (in the ng range for unlabeled antigen) or autoradiography (in the pg range for radiolabeled antigen) established the sensitivity and specificity of this method. Similar sensitivity could be obtained following conventional sodium dodecyl sulfate polyacrylamide gel electrophoresis after partial removal of the detergent and possible renaturation of proteins. Placement of a nitrocellulose sheet on the anodal side of the agarose gel produced a ‘negative replica’ (proteins/polypeptides not reacting with specific antibodies in the agarose gel). Counterimmunoblotting provides an additional method for molecular weight determination of protein antigens with sensitivity and specificity comparable to established nitrocellulose blotting (unlabeled proteins) or immunoprecipitation (labeled proteins) procedures.

We have described the protein, enzyme, and isoenzyme characteristics of three gross fractions of both normal and abnormal human sera, as obtained by application of high centrifugal force. In the absence of solution gradient, such fractions represent pure and undiluted elements of the serum; they are reproducible and sufficiently voluminous for extensive analytical study. Specific features of these fractions may be of interest in planning additional or peripheral investigations of serum. Fraction I appears to be a fair sample of native serum water; Fraction II appears to segregate the pre-β-globulin lipoprotein component observed in some sera; Fraction III is a concentrated solution of LDH, CPK, and SGOT enzymes, and γ-globulin-rich protein, which is hpoprotein-free. More than 95% of the LDH, CPK, and SGOT is located in Fractions II and III. Quantitative activity and qualitative nature of these enzymes appears to survive the stress of the ultracentrifuge technique relatively well.

Various birch-pollen and dog-epithelium allergen extracts were chromatographed using Sephadex G-75 and Sephadex G-200 columns. The chromatographic tractions were then tested by an in vitro paper disc radioallergosorbent test, using sera from allergen-sensitive patients. Calibrated columns were used to approximate molecular weights of some birch-pollen and dog-epithelium allergenic active components.

1. 1. The protein composition of rat serum and whey was studied by paper electrophoresis in non-lactating rats and rats on the 13th and 20th days of lactation, and the turnover of serum proteins and their transfer to the milk were measured using 131I-labelled purified rat albumin, acidic α1-glycoprotein, haptoglobin, transferrin and γ-globulin. 2. 2. Lactation was accompanied by a decrease in serum albumin concentration and by increases of the α- and β-globulins. Whey contained lower concentrations of the electrophoretic fractions, but showed a marked increase in β-globulin between the 13th and 20th days of lactation. The fractional and absolute turnover rates of all five proteins were greater in the lactating than in the non-lactating rats, and all of the proteins were transferred to the milk. It is concluded that the rates of catabolism of all the proteins were increased during lactation due to loss into the milk, and that there was also an increase in their rates of synthesis. With the exception of transferrin the relative rates of transmission of the proteins to whey was in inverse relation to their molecular weight, suggesting that the mammary gland acts as a molecular sieve for serum proteins.

Serum α1-antitrypsin, α1-acid glycoprotein, baptoglobin, ceruloplasmin and C-reactive protein are increased, albumin, transferrin, α1-and β-lipoprotein are decreased as an early response to tissue trauma and inflammatory disease. In infection these changes are followed by a rise of γ-globulins.

Bisalbuminaemia in two members of a Kashmiri family is reported. This, the first Asian variant, is described in terms of its electrophoretic mobilities and dye-binding properties.

SummaryIf proteins are added to homogenates of organs before paper electrophoresis, better separation and increased activity of the LDH isozymes is obtained. This increase was confirmed by the spectrophotometric determination of the formazan produced. A mixture of human albumin and gamma globulin in the normal serum ratio (4:1) gives a good electrophoretic resolution of the five isozymes.

A double antibody heterologous enzyme immunoassay was developed for measuring thyroxine (T4) in serum and in dried blood samples on filter paper for use in screening for neonatal hypothyroidism. In this method, ethanol extracts of 100 microliter of serum or dried blood spots of 9 mm in diameter were incubated with T4-alkaline phosphatase conjugate prepared with glutaraldehyde, and antiserum to T4-bovine serum albumin conjugate prepared with carbodiimide. The enzyme activity in the precipitates formed with second antibody was then determined photometrically at 500 nm. The measurable range of T4 was 1-32 micrograms/dl. A linear relation was obtained between the sample volume and the T4 value, and a high correlation was found between values for T4 determined by this method and those for T4 in serum determined by radioimmunoassay (coefficient of correlation: r=0.97 for serum and r=0.88 for dried blood samples).

RAST was performed using both nitrocellulose (NC) and paper discs to compare these solid supports for ability to detect IgE antibodies in sera from two patients with hypersensitivity to the industrial chemical, diphenylmethane-4,4'-diisocyanate (MDI). NC disc had distinct advantages in ease of coupling the hapten-conjugate antigen to discs, and in use of lesser amounts of antigen. With regard to sensitivity, NC discs were better able to distinguish the positive sera from 34 control sera including those with elevated levels of total IgE. In both RAST systems, inhibition studies indicated high specificity of antibodies for MDI, with no reactivity detected toward the serum albumin portion of the MDI-HSA conjugate antigen. However, only in the NC RAST did antibodies from both patients react with p-tolyl isocyanate inhibitor. Based on the above results, NC discs displayed several advantages in RAST and are recommended for routine serological assay of isocyanate-specific antibodies.

Intrasplenic immunization with antigen immobilized on nitrocellulose (NC) paper results in an immune response with nanogram amounts of antigen without the use of Freund's adjuvant. Comparing the sensitivity of the intrasplenic immunization with intraperitoneal or subcutaneous administration, we found that the intrasplenic method resulted in more positive animals with higher titres than did the other techniques with the smallest amount of antigen (70 ng of bovine serum albumin). With larger amounts of albumin the intraperitoneal method yielded the highest titres. No loss of antigenicity was observed when we immunized with equal amounts of protein separated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), immunoblotted and stained with either Coomassie brilliant blue R 250 or Amido black 10 B.

Paper disc-electroimmunodiffusion in agarose gel provides a rapid and sensitive quantitation of the immunoprecipitin reaction.

Serum proteins of pregnant rats were analyzed by paper electrophoresis following administration of the teratogenic disazo dyes trypan blue, Evans blue, Niagara blue 4B, Niagara sky blue 6B, Congo red, and Niagara blue 2B. Sera were obtained from blood taken by cardiac puncture just before dye injection, 48 hours after dye injection; and again at autopsy. All of the dyes tested caused a reduction in serum albumin and total protein concentration and an elevation in the concentration of beta or alpha-2 globulins at some time during pregnancy. The remaining serum fractions reacted variably to the dye treatment. In spite of the rather consistent results presented in this paper, and similar findings reported for other teratogens, there is no direct proof that altered serum proteins, per se, are causally related to the production of malformations.