A nanohybrid composed of Prussian Blue and graphitic C3N4 nanosheets as the signal-generating tag in an enzyme-free electrochemical immunoassay for the neutrophil gelatinase-associated lipocalin.

An enzyme-free electrochemical immunoassay is described for the neutrophil gelatinase-associated lipocalin (NGAL; a biomarker of kidney disease). Prussian Blue (PB) nanoparticles with redox activity were deposited on graphitic C3N4 nanosheets (g-C3N4) by in-situ reduction. A screen printed electrode (SPCE) was modified with antibody against NGAL, and the PB-g-C3N4 nanohybrid was used as the signal-generating tag for the secondary antibody against NGAL. Upon addition of target NGAL and of secondary antibody, a sandwich is formed on the SPCE. At an applied potential of typically 0.13 V (vs. Ag/AgCl), a well-defined voltammetric peak is observed that results from the presence of PB on the secondary antibody. Under optimal conditions, the peak current increases linearly in the 0.01 to 10 ng·mL-1 NGAL concentration range, and the detection limit is 2.8 pg·mL-1. An average precision of <12% was accomplished in the batch-to-batch mode. Other disease-related biomarkers do not interfere. The accuracy and inter-laboratory validation of this method were evaluated for target NGAL detection in spiked human serum by using a commercial ELISA. The results obtained by the two methods are in good accordance. Graphical abstract An enzyme-free electrochemical immunoassay was used for detection of neutrophil gelatinase-associated lipocalin by Prussian blut/graphitic-C3N4 nanohybrids as the signal-generation tags.

Observation of Whether to Mix Evenly the Serum Samples Preserved at-20℃ for Clinical Routine Biochemical Test Results / 现代检验医学杂志

Objective To explore the change of conventional biochemical test results of serum specimens saved-20℃ and blending of its effects.Methods The fresh serum of 24 patients were conducted routine biochemical tests,respectively in four groups of numbers in the same capacity of 1 ml of the sample tube,a set of 25℃ kept 24 hours a day,a group of 4 ℃ refrigerated for 24 hours,24 hours at-20℃ save the two groups (a group was not incorporated,a set of blended),and the four groups of serum samples in biochemical results comparing with the initial results.Results 25℃ at room temperature preservation after 24 hours,ALT,AST,TBIL and DBIL biochemical indicators of four average were below the initial results (t=2.130,2.308,2.130 and 2.308,P=0.042,0.029,0.042 and 0.003),there were no statistically significant difference between the rest of the biochemical index results comparison (P＞ 0.05).4℃ refrigerator after 24 hours,TBIL,DBIL levels below the initial level (t=2.103 and 2.089,P=0.045 and 0.046),and the rest of the biochemical indicators to compare differences had no statistical significance (P＞0.05).-20℃ refrigerated in the two groups of samples,not each sample of serum biochemical results compared with the initial results,were kept statistically significant difference (t=-4.218～11.710,all P＜0.05),while serum samples of 15 items and biochemical indexes of blending the results compared with the initial results,the average level of had no statistical significance (P＞0.05).Conclusion Serum samples of the chemical composition of the homogeneity in the 4 ℃ refrigerator will not change,but will not be able to timely detection of serum samples in the preservation,and minus-20 ℃ refrigerator on the serum samples of a significant difference was found in the lower concentration of chemical components,compete on low,and tests conducted before fully blending can ensure the precision of its biochemical test results.

Highly pathogenic avian influenza A(H5N1) mutants transmissible by air are susceptible to human and animal neutralizing antibodies.

A laboratory-generated reassortant H5 hemagglutinin (HA)/influenza A(H1N1) strain containing 4 mutations in influenza A(H5N1) HA has become transmissible by air among mammals. Here, we constructed 15 influenza A(H5N1) pseudoviruses containing a single mutation or a combination of mutations and showed that the pseudoviruses were susceptible to neutralizing antibodies from patients with influenza A(H5N1) infection and from mice immunized with a vaccine containing the conserved HA1 sequence of influenza A(H5N1). These results indicate that antibodies in patients currently infected by influenza A(H5N1) and antibodies induced by vaccines containing conserved sequences in HA1 of wild-type influenza A(H5N1) are highly effective in cross-neutralizing future influenza A(H5N1) mutants with airborne transmissibility, suggesting that human influenza pandemics caused by these influenza A(H5N1) variants can be prevented.