Label-free genotyping of cytochrome P450 2D6*10 using ligation-mediated strand displacement amplification with DNAzyme-based chemiluminescence detection

Development of a cross-priming isothermal amplification assay based on the glycoprotein B gene for instant and rapid detection of feline herpesvirus type 1

A cross-priming isothermal amplification (CPA) assay was developed for detection of feline herpesvirus type 1 (FHV-1). In this assay, the target fragment of the FHV-1 glycoprotein B gene is amplified rapidly by Bst DNA polymerase at a constant temperature (63 °C, 45 min), using a simple thermostat. The assay had no cross-reactions with four types of feline viruses, and the detection limit was 10⁰ copies/μl. The positive rate of clinical samples from CPA was 100% consistent with qPCR but higher than ordinary PCR, indicating its superiority to ordinary PCR. Visualization was achieved using SYBR Green I dye.

Development of a chemiluminescent aptasensor for ultrasensitive and selective detection of aflatoxin B1 in peanut and milk

More and more attention about food safety leads to a research hotspot to develop new detection methods for food contaminant. To address the problems of serious interference and low sensitivity, a chemiluminescent aptasensor for the detection of aflatoxin B1(AFB1) in food was developed in this paper. It is based on horseradish peroxidase (HRP) catalyze the luminol chemiluminescence reaction. The hybridization chain reaction (HCR) signal amplification strategy has been used to improve the detection sensitivity. Magnetic separation could further reduce background signal obviously at the same time. AFB1 as a model of analyte to test the capability of our developed assay system. Under the optimal experimental conditions, CL intensity showed a good linear correlation with the concentrations of AFB1 ranging from 0.5 to 40 ng mL^-1. The limit of detection was estimated 0.2 ng mL^-1 based on 3 times of the signal-to-noise ratio which is lower than those of the previously reported sensors. It could be used to detect AFB1 content in real samples, such as peanuts and milk which were purchased in local supermarket. The results proved that the sensing system has good anti-interference and selectivity. In all, it has potential for practical application in food safety field.

A novel restriction endonuclease GlaI for rapid and highly sensitive detection of DNA methylation coupled with isothermal exponential amplification reaction

Sensitive and accurate detection of site-specific DNA methylation is of critical significance for early diagnosis of human diseases, especially cancers. Herein, for the first time we employ a novel methylation-dependent restriction endonuclease GlaI to detect site-specific DNA methylation in a highly specific and sensitive way by coupling with isothermal exponential amplification reaction (EXPAR). GlaI can only cut the methylated target site with excellent selectivity but leave the unmethylated DNA intact. Then the newly exposed end fragments of methylated DNA can trigger EXPAR for highly efficient signal amplification while the intact unmethylated DNA will not initiate EXPAR at all. As such, only the methylated DNA is quantitatively and faithfully reflected by the real-time fluorescence signal of the GlaI-EXPAR system, and the potential false positive interference from unmethylated DNA can be effectively eliminated. Therefore, by integrating the unique features of GlaI for highly specific methylation discrimination and EXPAR for rapid and powerful signal amplification, the elegant GlaI-EXPAR assay allows the direct quantification of methylated DNA with ultrahigh sensitivity and accuracy. The detection limit of methylated DNA target has been pushed down to the aM level and the whole detection process of GlaI-EXPAR can be accomplished within a short time of 2 h. More importantly, ultrahigh specificity is achieved and as low as 0.01% methylated DNA can be clearly identified in the presence of a large excess of unmethylated DNA. This GlaI-EXPAR is also demonstrated to be capable of determining site-specific DNA methylations in real genomic DNA samples. Sharing the distinct advantages of ultrahigh sensitivity, outstanding specificity and facile operation, this new GlaI-EXPAR strategy may provide a robust and reliable platform for the detection of site-specific DNA methylations with low abundances.

DNAzyme based gap-LCR detection of single-nucleotide polymorphism

Fast and accurate detection of single-nucleotide polymorphism (SNP) is thought more and more important for understanding of human physiology and elucidating the molecular based diseases. A great deal of effort has been devoted to developing accurate, rapid, and cost-effective technologies for SNP analysis. However most of those methods developed to date incorporate complicated probe labeling and depend on advanced equipment. The DNAzyme based Gap-LCR detection method averts any chemical modification on probes and circumvents those problems by incorporating a short functional DNA sequence into one of LCR primers. Two kinds of exonuclease are utilized in our strategy to digest all the unreacted probes and release the DNAzymes embedded in the LCR product. The DNAzyme applied in our method is a versatile tool to report the result of SNP detection in colorimetric or fluorometric ways for different detection purposes.

Reusable light-emitting-diode induced chemiluminescence aptasensor for highly sensitive and selective detection of riboflavin

A novel reusable chemiluminescence aptasensor was developed based on aptamer recognition coupled with light-emitting-diode induced chemiluminescence (LED-CL) detection. The sensing approach was based on the design that the model analyte riboflavin (Rf) in sample solutions was captured by the immobilized aptamers and then eluted simply with alkaline luminol solution to catalyze the CL reaction between luminol and dissolved oxygen under high power LED irradiation. This design allowed a very simple (branch-free) flow way for the CL sensing system. The CL intensity versus the Rf concentration was linear in the range from 0.03 to 5ngmL(-1) with a limit of detection (LOD) down low to 8pgmL(-1). Without renewing the aptamer, the relative standard deviation (RSD) for seven consecutive detections is 2.33%; the sensor also showed good stability without performance deterioration after >100 times use. Up to 10000-fold of K(+), Na(+), Ca(2+), Mg(2+), and Fe(3+), 5000-fold for glucose and bovine serum albumin, 1000-fold of uric acid, 1500-fold of ascorbic acid (added with Fe(3+)), 100-fold of flavin mononucleotide and 200-fold of flavin adenine dinucleotide caused no significant interference with the determination of 0.5ngmL(-1) Rf. The sensor was applied for analysis of Rf in urine and food samples with the recovery of 94-103%. The advantages of reusability, simplicity, high sensitivity and selectivity provided by the LED-CL aptasensor will make it a good alternative tool for biological and food analysis.