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Fatty acids (FAs) play a vital physiological role in lipid metabolism, which is reported as potential diagnostic biomarker for various diseases. Thus, it is urgent to develop a credible method that can profile FA metabolism with a holistic view. Here, a targeted strategy to screen FAs was developed by parallel labeling with d 0 /d 6 -dansylhydrazine (d 0 /d 6 -DnsHz) and using ultra-high performance liquid chromatography coupled with high-resolution tandem mass spectrometry (UPLC–MS/MS) in data-dependent MS/MS (ddMS2) mode. The simple and mild derivatization procedure within 3 h allowed for a significant improvement in sensitivity. Additionally, the characteristic product ions introduced by the derivatization reagent assist to identify the unknown FA species. A quantitation method was established by multiple reaction monitoring (MRM) and the d 6 -DnsHz tagged standards for each analyte were used as internal standards to overcome the matrix effects. By applying the method to determine FA levels in plasma collected from the esophageal squamous cell carcinoma (ESCC) patients and healthy controls, 65 FA metabolites were characterized and six FAs were found to be altered by the invasion of tumors. The parallel derivatization strategy provides insights into the identification of unknown FAs and paves a new way for targeted metabolomics. Also, this novel method is a powerful tool for characterization and quantification of FAs in biological samples, which shows a great potential application in clinical diagnosis and investigation of disease mechanisms. [Display omitted] • A novel parallel derivatization strategy was developed to identify FAs in biosample. • Dansylhydrazine-based derivatization enhanced ionization efficiency of FAs. • The isotope-labeled standard provides one-to-one internal standard for FA analysis. • Six FAs were screened out as potential diagnostic biomarkers of ESCC. [ABSTRACT FROM AUTHOR]

Some non-coding RNAs are abnormally expressed during the occurrence and development of diseases, so it is necessary to develop analytical methods that can specifically and sensitively detect them. In typical CRISPR/Cas12a system, a complete crRNA that can recognize single-stranded or double-stranded DNA is necessary to activate its trans -cleavage activity, which limits its direct application in RNA detection. Here, we prospectively find that slicing the facilitated crRNA in the typical CRISPR/Cas12a system at a fitted site did not affect its trans -cleavage activity, and a m ini c rRNA- m ediated CRISPR/Cas12a system (MCM-CRISPR/Cas12a) was proposed based on this. This system can detect non-coding RNA to pM-level (10 pM for miRNA-21). To expand the application of this system, we combined it with HCR and CHA to establish a detection platform for non-coding RNA. The results show that the proposed method can specifically detect RNA to fM-level (2.5 fM for miRNA-21, 8.98 fM for miR-128–3p, and 81.6 fM for lncRNA PACER). The spiked recovery rates of miRNA-21, miR-128–3p, and lncRNA PACER in normal human serum were in range from 104.7 to 109.4 %, indicating the proposed method owns good applicability. In general, this MCM-CRISPR/Cas12a system further breaks the limitations of the typical CRISPR/Cas12a system that cannot be directly used for non-coding RNA detection. Besides, its combination with HCR and CHA achieves highly sensitive detection of non-coding RNA. [Display omitted] • Finding slicing the facilitated crRNA suitably did not affect the trans -cleavage activity of CRISPR/Cas12a system. • Proposing MCM-CRISPR/Cas12a system to directly detect RNA. • Constructing RNA detection platform by combining MCM-CRISPR/Cas12a system, HCR, and CHA. [ABSTRACT FROM AUTHOR]