Artificial nucleic acid circuits with precisely controllable dynamic and function have shown great promise in biosensing, but their utility in molecular diagnostics is still restrained by the inability to process genomic DNA directly and moderate sensitivity. To address this limitation, we present a CRISPR-Cas–powered catalytic nucleic acid circuit, namely, CRISPR-Cas–only amplification network (CONAN), for isothermally amplified detection of genomic DNA. By integrating the stringent target recognition, helicase activity, and trans-cleavage activity of Cas12a, a Cas12a autocatalysis-driven artificial reaction network is programmed to construct a positive feedback circuit with exponential dynamic in CONAN. Consequently, CONAN achieves one-enzyme, one-step, real-time detection of genomic DNA with attomolar sensitivity. Moreover, CONAN increases the intrinsic single-base specificity of Cas12a, and enables the effective detection of hepatitis B virus infection and human bladder cancer–associated single-nucleotide mutation in clinical samples, highlighting its potential as a powerful tool for disease diagnostics.

Phthalic acid esters (PAEs) are a class of lipophilic chemicals widely used as plasticizers and additives to improve various products’ mechanical extensibility and flexibility. At present, synthesized PAEs, which are considered to cause potential hazards to ecosystem functioning and public health, have been easily detected in the atmosphere, water, soil, and sediments; PAEs are also frequently discovered in plant and microorganism sources, suggesting the possibility that they might be biosynthesized in nature. In this review, we summarize that PAEs have not only been identified in the organic solvent extracts, root exudates, and essential oils of a large number of different plant species, but also isolated and purified from various algae, bacteria, and fungi. Dominant PAEs identified from natural sources generally include di-n-butyl phthalate, diethyl phthalate, dimethyl phthalate, di(2-ethylhexyl) phthalate, diisobutyl phthalate, diisooctyl phthalate, etc. Further studies reveal that PAEs can be biosynthesized by at least several algae. PAEs are reported to possess allelopathic, antimicrobial, insecticidal, and other biological activities, which might enhance the competitiveness of plants, algae, and microorganisms to better accommodate biotic and abiotic stress. These findings suggest that PAEs should not be treated solely as a “human-made pollutant” simply because they have been extensively synthesized and utilized; on the other hand, synthesized PAEs entering the ecosystem might disrupt the metabolic process of certain plant, algal, and microbial communities. Therefore, further studies are required to elucidate the relevant mechanisms and ecological consequences.

The detection of microRNA expression profiles plays an important role in early diagnosis of different cancers. On the basis of the employment of redox labels with distinct potential positions and duplex specific nuclease (DSN)-assisted target recycling signal amplifications, we have developed a multiplexed and convenient electronic sensor for highly sensitive detection of microRNA (miRNA)-141 and miRNA-21. The sensor is constructed by self-assembly of thiol-modified, redox species-labeled hairpin probes on the gold sensing electrode. The hybridizations between the target miRNAs and the surface-immobilized probes lead to the formation of RNA/DNA duplexes, and DSN subsequently cleaves the redox-labeled hairpin probes of the RNA/DNA duplexes to recycle the target miRNAs and to generate significantly amplified current suppression at different potentials for multiplexed detection of miRNA-141 and miRNA-21 down to 4.2 and 3.0 fM, respectively. The sensor is also highly selective toward the target miRNAs and can be employed to monitor miRNAs from human prostate carcinoma (22Rv1) and breast cancer (MCF-7) cell lysates simultaneously. The sensor reported here thus holds great potential for the development of multiplexed, sensitive, selective, and simple sensing platforms for simultaneous detection of a variety of miRNA biomarkers for clinic applications with careful selection of the labels.