Rapid and Sensitive Chemiluminescent Enzyme Immunoassay for the Determination of Neomycin Residues in Milk

Immunoassays greatly contribute to veterinary drug residue analysis. However, there are few reports on detecting neomycin residues by immunoassay. Here, a rapid and sensitive chemiluminescent enzyme immunoassay （CLIEA） was successfully developed for neomycin residue analysis. CLIEA demonstrated good cross-reactivity for neomycin, and the IC50 value was 2.4 ng/mL in buffer.

Antibody Production for a Rapid Fluorescence Polarization Immunoassay of Estrone

Estrone has been identified as a potential endocrine-disrupting chemical （EDC）[1]. Estrone is usually quantified by gas chromatography-mass spectrometry （GC-MS）, GC-MS/MS, high performance liquid chromatography （HPLC）, HPLC- MS, and HPLC-MS/MS, etc.[2-3]. Meanwhile, several immunoassays based on radioimmunoassay, enzyme linked immunosorbent assay （ELISA） or chemiluminescence immunoassay （CLIA） for determination of estrone in real samples have been developed[2＇4]. Although these methods are sensitive, they need multistage separation and are thus time-consuming and laborious. A very promising way for the simplification of immunoassays for routine applications is a shift from heterogeneous methods （with separation） to homogeneous assays （without separation）[5]. Fluorescence polarization immunoassay （FPIA） is one of the homogeneous techniques that meets the requirements of a simple, reliable, fast, and cost-effective analysis[6]. Therefore, the present study is focused on the development of FPIA in order to analyze estrone based on antibody production.

Rapid Detection of Wheat Blast Pathogen Magnaporthe oryzae Triticum Pathotype Using Genome-Specific Primers and Cas12a-mediated Technology

Wheat blast,caused by the fungus Magnaporthe oryzae Triticum(MoT)pathotype,is a devastating disease persistent in South America and Bangladesh.Since MoT generally fails to cause visual symptoms in wheat until the heading stage when the infection would have advanced,disease control by fungicide application solely based on the detection of visual symptoms is ineffective.To develop an accurate and sensitive method to detect MoT at the seedling and vegetative stages for disease control,we sequenced the genomes of two MoT isolates from Brazil and identified two DNA fragments,MoT-6098 and MoT-6099,that are present in the MoT genome but not in the genome of the rice-infecting Magnaporthe oryzae Oryzae(MoO)pathotype.Using polymerase chain reaction(PCR),we confirmed the specificity of the two markers in 53 MoT and MoO isolates from South America and Bangladesh.To test the efficiency of the two markers,we first established a loop-mediated isothermal amplification(LAMP)method to detect MoT at isothermal conditions,without the use of a PCR machine.Following this,we used the Cas12a protein and guide RNAs(gRNAs)to target the MoT-6098 and MoT-6099 sequences.The activated Cas12a showed indiscriminate single-stranded deoxyribonuclease(ssDNase)activity.We then combined targetdependent Cas12a ssDNase activation with recombinase polymerase amplification(RPA)and nucleic acid lateral flow immunoassay(NALFIA)to develop a method that accurately,sensitively,and cost-effectively detects MoT-specific DNA sequences in infected wheat plants.This novel technique can be easily adapted for the rapid detection of wheat blast and other important plant diseases in the field.

SBA-15 Modified Carbon Paste Electrode for Rapid cTnI Detection with Enhanced Sensitivity

A novel electrochemical immunoassay for cardiac troponin Ⅰ （cTnI） combining the concepts of the dual monoclonal antibody ＂sandwich＂ principle, the silver enhancement on the nano-gold particle, and the SBA-15 mesoporous modified carbon paste electrode （SBA-MCPE） is described. Four main steps were carried out to obtain the analytical signal, i.e., electrode preparation, immunoreaction, silver enhancement, and anodic stripping voltammetric detection. A linear relationship between the anodic stripping peak current and concentration of cTnI from 0.5 to 5.0 ng/mL and a limit of detection of 0.2 ng/mL of cTnI were obtained.