Jiang Zhou

Amino‐containing metabolites play essential roles in biological processes such as protein synthesis and energy metabolism, and their dysregulation is associated with disease development. Liquid biopsy, valued for its minimal invasiveness, is widely utilized in cancer detection. However, traditional methods necessitate protein and lipid removal while suffering from low throughput and sensitivity. To address these limitations, a novel magnetic chemoselective probe, Fe ₃ O ₄ ‐Polymers‐Cystamine‐Boclys‐Gly‐NH ₂ ‐PITC (FPBG‐PITC), is synthesized, incorporating hydrophobic tags to improve metabolite detection sensitivity and chromatographic separation. Using this probe, a high‐throughput metabolic analysis platform is established, allowing efficient enrichment, purification, and quantification of serum amino‐containing metabolites with reduced costs. Through comparative analysis of serum samples from healthy controls and patients with benign or malignant breast lesions, four metabolites—asparagine, tryptophan, leucine/isoleucine, and homocitrulline—are identified as potential biomarkers for early breast disease screening, providing a novel diagnostic strategy.

Direct analysis in real time mass spectrometry (DART-MS) has recently emerged as a promising approach for measuring semi-volatile organic compounds (SVOCs) on indoor surface films. However, its broader application in indoor environments is limited by low measurement repeatability and no separation of isomers. Herein we developed a sampling suite of indoor surface films for DART-MS analysis, optimized settings of DART to obtain higher analytical performance, and demonstrated the possibility of separating isomeric compounds using tandem mass spectrometry (MS/MS). Two pairs of isomeric phthalate esters, including di(2-ethylhexyl) phthalate (DEHP) and di-n-octyl phthalate (DnOP) and diisobutyl phthalate (DiBP) and di-n-butyl phthalate (DnBP), were used as examples for method optimization and validation. Under optimized conditions, the instrument responses for all four compounds exhibited good linearity (r>0.992) and acceptable repeatability (intraday relative standard deviation (RSD) < 11.0 %). The limits of quantification for the four phthalate esters ranged from 0.042 to 0.24 ng cm⁻². The uncertainty in the separation of isomeric components using MS/MS was < 11.4 %, which is acceptable for real sample analysis. To further assess the developed method, we analyzed 10 film samples collected side by side in an occupied office. DnOP was not detected. The RSD among samples was 6.1 % for DEHP, 4.6 % for DnBP, and 10.4 % for DiBP, indicating the overall good repeatability of the collection and measurement method developed. With improved performance, the developed method increases the feasibility of the DART-MS technique for monitoring the dynamics of chemical composition of indoor surface films.

Direct Analysis in Real Time Mass Spectrometry (DART-MS) is recently emerged as a promising approach for measuring semi-volatile organic compounds (SVOCs) in indoor surface films. However, its broader application in indoor environments is limited by low measurement repeatability and no separation of isomers. Herein we developed a sampling suite of indoor surface film for DART-MS analysis, optimized settings of DART to obtain higher analytical performance, and demonstrated the possibility of separating isomeric compounds using tandem mass spectrometry (MS/MS). Two pair of isomeric phthalate esters, including di(2-ethylhexyl) phthalate (DEHP) and di-n-octyl phthalate (DnOP), diisobutyl phthalate (DiBP) and di-n-butyl phthalate (DnBP), were used as examples for method optimization and validation. Under optimized conditions, the instrument responses for all four compounds exhibited good linearity (r > 0.992) and acceptable repeatability (intraday RSD < 11.0%). The limits of quantification for the four PAEs ranged from 0.042 to 0.24 ng/cm². The uncertainty in the separation of isomeric components using MS/MS was <11.4%, which is acceptable for real sample analysis. To further assess the developed method, we analyzed 10 film samples collected side by side in an occupied office. DnOP was not detected. The RSD among samples was 6.1% for DEHP, 4.6% for DnBP, and 10.4% for DiBP, indicating overall good repeatability of the collection and measurement method developed. With improved performance, the developed method increases the feasibility of the DART-MS technique for monitoring dynamics of chemical composition of indoor surface films.

Nucleic acid modifications play important roles in biological activities and disease occurrences, and have been considered as cancer biomarkers. Due to the relatively low amount of nucleic acid modifications in biological samples, it is necessary to develop sensitive and reliable qualitative and quantitative methods to reveal the content of any modifications. In this review, the key processes affecting the qualitative and quantitative analyses are discussed, such as sample digestion, nucleoside extraction, chemical labeling, chromatographic separation, mass spectrometry detection, and data processing. The improvement of the detection sensitivity and specificity of analytical methods based on mass spectrometry makes it possible to study low-abundance modifications and their biological functions. Some typical nucleic acid modifications and their potential as biomarkers are displayed, and efforts to improve diagnostic accuracy are discussed. Future perspectives are raised for this research field.

Polyurea-magnetic hierarchical porous composites show excellent physisorption performance for anionic metabolites in complex matrices with simple preparation, rapid separation, superior stability, and recyclability.

Bimolecular or tetramolecular G-quadruplexes (GQs) are predominantly self-assembled by the same sequence-identical G-rich oligonucleotides and usually remain inert to the strand displacement reaction (SDR) with other short G-rich invading fragments of DNA or RNA. Appealingly, in this study, we demonstrate that a parallel homomeric bimolecular GQ target of Tub10 d(CAGGGAGGGT) as the starting reactant, although completely folded in K⁺ solution and sufficiently stable (melting temperature of 57.7 °C), can still spontaneously accept strand invasion by a pair of short G-rich invading probes of P1 d(TGGGA) near room temperature. The final SDR product is a novel parallel heteromeric trimolecular GQ (tri-GQ) of Tub10/2P1 reassembled between one Tub10 strand and two P1 strands. Here we present, to the best of our knowledge, the first NMR solution structure of such a discrete heteromeric tri-GQ and unveil a unique mode of two probes vs one target in mutual recognition among G-rich canonical DNA oligomers. As a model system, the short invading probe P1 can spontaneously trap G-rich target Tub10 from a Watson-Crick duplex completely hybridized between Tub10 and its fully complementary strand d(ACCCTCCCTG). The Tub10 sequence of d(CAGGGAGGGT) is a fragment from the G-rich promoter region of the human β2-tubulin gene. Our findings provide new insights into the Hoogsteen pairing-based SDR between a GQ target and double invading probes of short G-rich DNA fragments and are expected to grant access to increasingly complex architectures in GQ-based DNA nanotechnology.

Amino metabolites are essential for life activities and can be used clinically as biomarkers for disease diagnosis and treatment. Solid-phase-supported chemoselective probes can simplify sample handling and enhance detection sensitivity. However, the low efficiency and complicated preparation of traditional probes limit their further application. In this work, a novel solid-phase-supported probe Fe₃O₄-SiO₂-polymers-phenyl isothiocyanate (FSP-PITC) was developed by immobilizing phenyl isothiocyanate on magnetic beads with disulfide as an orthogonal cleavage site, which can couple amino metabolites directly regardless of whether proteins and other matrixes were removed. After purification, the targeted metabolites were released by dithiothreitol and detected by high-resolution mass spectrometry. The simplified processing steps shorten the analysis time, and the introduction of polymers results in a 100-1000-fold increase in probe capacity. With high stability and specificity, FSP-PITC pretreatment allows accurate qualitative and quantitative (R² > 0.99) analysis, facilitating the detection of metabolites in subfemtomole quantities. Using this strategy, 4158 metabolite signals were detected in negative ion mode. Among them, 352 amino metabolites including human cells (226), serum (227), and mouse samples (274) were searched from the Human Metabolome Database. These metabolites participate in metabolic pathways of amino acids, biogenic amine, and the urea cycle. All these results indicate that FSP-PITC is a promising probe for novel metabolite discovery and high-throughput screening.