•We developed an aptamer-based immunoassay to detection MC-LR.•The specificity was promoted by this aptamer-MC-LR-antibody sandwich method.•A portable analyzer was used to test the chemiluminescence signals catalyzed by HRP.•It proved a simple quantitative method to detect MC-LR in the field by a single analyst.The rapid detection of microcystin-leucine-arginine (MC-LR), the most highly toxic among MCs, is significantly important to environmental and human health protection and prevention of MC-LR from being used as a bioweapon. Although aptamers offer higher affinity, specificity, and stability with MC-LR than antibodies in the immunodetection of MC-LR due to steric hindrance between two antibodies and limited epitopes of MC-LR for use in a sandwich immunoassay, no sandwich immunoassay using an aptmer has been developed for MC-LR detection. This study is aimed at developing an aptamer-antibody immunoassay (AAIA) to detect MC-LR using a portable analyzer. The aptamers were immobilized onto the glass surface of a microchamber to capture MC-LR. MC-LR and horseradish peroxidase (HRP)-labeled antibody were pulled into the microchamber to react with the immobilized aptamer. The chemiluminescence (CL) catalyzed by HRP was tested by a photodiode-based portable analyzer. MC-LR at 0.5–4.0 μg/L was detected quantitatively by the AAIA, with a CL signal sensitivity of 0.3 μg/L. The assay took less than 35 min for a single sample and demonstrated a high specificity, detecting only MC-LR, but not MC-LA, MC-YR, or nodularin-R. The recovery of two spiked real environmental samples calculated as 94.5–112.7%. Therefore, this AAIA was proved to be a rapid and simple method to detect MC-LR in the field by a single analyst.

To develop a simple micro-platform for gene mutation detection, we used a DNA hybridization approach in a combined microchannel. A glass groove immobilized with oligonucleotide probes by UV-crosslinking, and encased in a transparent heat-shrinkable polythene tube. After heat treatment, the polythene tube stretched tightly over the glass groove and was designated as a combined capillary chip (CCC). The CCC assay was optimized with 10 μL reaction solutions shuttling back and forth at 50 μL min−1 for 10 min, give a detection minimum of 0.1 nM target DNA sequences. In hepatitis B virus (HBV) YMDD mutations detection, 61.3% (92/150) was of a single genotype and it was authenticated with sequence analysis. The other 38.7% (58/150) was mixed genotype detected, but 18.9% (11/58) has a missed diagnosis in sequence analysis. It proved a higher sensitivity than sequence analysis. The CCC assay has a simple fabricating process, simple structure and higher specificity in gene mutation detection. These features are promising for clinical gene mutation analysis.

The quantitative measurement of serum hepatitis B surface antigen (HBsAg) is important for monitoring anti-hepatitis B virus (HBV) therapy and evaluating the safety of blood products or blood transfusion. This study is aimed at generating and evaluating a capillary-based chemiluminescence immunoassay for the simple and rapid detection of human serum HBsAg. A simple and rapid capillary chemiluminescence immunoassay (CCIA) was developed using a portable analyzer for quantitatively detecting the levels of HBsAg in human serum. The experimental conditions were optimized, and the sensitivity and specificity of the CCIA were validated in positive HBsAg (HBsAg+) and negative HBsAg (HBsAg−) human sera. The CCIA quantitatively detected the levels of human serum HBsAg at 0.4–15.0 ng/mL, which resulted in dose-dependent increases in the chemiluminescence (CL) signals, with a sensitivity of 0.3 ng/mL. The assay took only 25 min for the analysis of a single sample. The CCIA only detected HBsAg, but not hepatitis C virus (HCV), human immunodeficiency virus-1 (HIV-1) p24, Treponema (TP) antigens, or other serum proteins and lipids tested with a specificity of 100 %. The CCIA for detecting HBsAg was reproducible, with a low intra-assay coefficient of variation (CV) (6.7 %) and inter-assay CV (7.4 %). The validation of 280 known HBsAg+ or HBsAg− clinical serum samples revealed that the CCIA detected 97.5 % of HBsAg+ sera without false-positives, with a sensitivity and specificity similar to that of the Architect i2000SR HBsAg assay (Kappa value = 0.983). The CCIA is a simple and rapid method for quantitatively measuring the levels of serum HBsAg to monitor anti-HBV therapy and evaluate the safety of blood samples for transfusion.