An extracellular electron transfer enhanced electrochemiluminescence aptasensor for Escherichia coli analysis.

As a crucial indicator in food and water safety testing, the detection of Escherichia coli plays a significant role in maintaining environmental sanitation and promoting public health. Herein, based on the electrochemical activity characteristics of E. coli, we established an enhanced electrochemiluminescence aptasensor for E. coli analysis. This study presents a new method for accurate identification by utilizing a double aptamer recognition system. Specifically, a nano-cadmium sulfide (CdS) modified aptamer was used for primary labeling, while a second aptamer was immobilized on a graphene/chitosan composite electrode for re-capture. The use of two aptamers improves the accuracy of the identification process. Furthermore, the application of an electrode potential facilitates continuous electron transfer between the electrode and electrochemically active microorganisms, resulting in an enhanced electroluminescence signal in relation to the metabolic status. This strategy possesses better sensitivity, accuracy, and stability, demonstrating its potential for E. coli analysis.

Target-cycling synchronized rolling circle amplification strategy for biosensing Helicobacter pylori DNA.

Helicobacter pylori is closely linked to many gastric diseases such as gastric ulcers and duodenal ulcers. Therefore, biosensing H. pylori has attracted wide attention from both scientists and clinicians. Here, we proposed an electrochemiluminescence (ECL)-based platform that could sensitively detect H. pylori DNA. In this platform, a novel target-cycling synchronized rolling circle amplification was used for signal amplification. Silver nanoclusters (Ag NCs) were synthesized on the circle DNA products, embedding them with the ability to catalyze the electrochemical reduction of K2 S2 O8 , in turn resulting in rapid consumption of the ECL co-reactant near the working electrode, and leading to a decrease in the ECL emission intensity. In addition to its excellent stability and selectivity, the proposed strategy had a low detection limit of 10 pM, an indication that it can be beneficially applied to test biosamples. Furthermore, a biosensing chip was designed to improve the throughput and shed new light on large-scale clinical biosensing applications.

A CRISPR/Cas12a-assisted array for Helicobacter pylori DNA analysis in saliva.

Helicobacter pylori infection has become a threat to the world populations. This leads to an urgent need of an efficient and convenient approach to accurately diagnose H. pylori infection. Saliva-based diagnoses are particularly welcomed for their efficiency and convenience. Aiming at saliva sample analysis, we proposed a CRISPR/Cas12a-assisted array, which had integrated H. pylori concentration detection and genotype screening functions. Single-nucleotide variations (SNVs) could be distinguished using the screening array with different probes, and an isothermal cycling strategy was combined with the trans-cleavage activity of Cas12a for signal amplification to improve accuracy of the diagnosis. As a demonstration, the SNV screening array was fabricated by utilizing the hybridization efficiency difference caused by mismatched bases. The array was able to successfully distinguish between ten H. pylori genotypes, and combined with the successful SDA biosensing, it had a LOD of as low as 60 fM. It was also able to diagnose H. pylori infection in saliva samples from infected patients. Together, the developed array has a potential in large-scale clinical screening and is a promising tool for the diagnosis and prevention of H. pylori infection-related diseases.

Genome mining of Streptomyces sp. CB00271 as a natural high-producer of ß-rubromycin and the resulting discovery of ß-rubromycin acid.

ß-rubromycin (ß-RUB) (1) is an efficient inhibitor of human telomerase possessing a unique spiroketal moiety as a potential pharmacophore and regarded as a promising anticancer drug lead. But the development of (ß-RUB) (1) has long been hampered by its low titer and very poor water solubility. By adopting a genome mining strategy, an FAD-dependent monooxygenase RubN involving with the formation of the spiro system was applied as the probe and Streptomyces sp. CB00271 was screened out from our strain collection as an alternative natural high producer of ß-RUB (1). After a series of fermentation optimizations, CB00271 could produce 124.8 ± 3.4 mg/L ß-RUB (1), which was the highest titer up to now. Moreover, the enhanced production of ß-RUB (1) in fermentation broth also led to the discovery of a new congener ß-RUB acid (7), which was structurally elucidated as the acid form of ß-RUB (1). Comparing to ß-RUB (1), the substituted carboxyl group endowed ß-RUB acid (7) much better solubility in serum and resulted in its higher activity towards tumor cells. Our work set up a solid base for the pilot-scale production of ß-RUB (1) and its congeners to facilitate their future development as promising anticancer drug leads, and also provide an alternative and practical strategy for the exploitation of other important microbial natural products.