Rapid Covalent-Probe Discovery by Electrophile-Fragment Screening.

Covalent probes can display unmatched potency, selectivity, and duration of action; however, their discovery is challenging. In principle, fragments that can irreversibly bind their target can overcome the low affinity that limits reversible fragment screening, but such electrophilic fragments were considered nonselective and were rarely screened. We hypothesized that mild electrophiles might overcome the selectivity challenge and constructed a library of 993 mildly electrophilic fragments.

Native Mass Spectrometry of Recombinant Proteins from Crude Cell Lysates.

Determining the properties of proteins prior to purification saves time and labor. Here, we demonstrate a native mass spectrometry approach for rapid characterization of overexpressed proteins directly in crude cell lysates. The method provides immediate information on the identity, solubility, oligomeric state, overall structure, and stability, as well as ligand binding, without the need for purification.

Multifunctional Magnetic Particles for Combined Circulating Tumor Cells Isolation and Cellular Metabolism Detection.

We for the first time demonstrate multi-functional magnetic particles based rare cell isolation combined with the downstream laser desorption/ionization mass spectrometry (LDI-MS) to measure the metabolism of enriched circulating tumor cells (CTCs). The characterization of CTCs metabolism plays a significant role in understanding the tumor microenvironment, through exploring the diverse cellular process. However, characterizing cell metabolism is still challenging due to the low detection sensitivity, high sample complexity, and tedious preparation procedures, particularly for rare cells analysis in clinical study.

Direct imaging of elemental distributions in tissue sections by laser ablation mass spectrometry.

We present a strategy for imaging of elements in biological tissues using laser ablation (LA) mass spectrometry (MS), which was compared to laser ablation inductively coupled plasma (LA-ICP) MS. Both methods were adopted for quantitative imaging of elements in mouse kidney, as well as traumatic brain injury model tissue sections. MS imaging (MSI) employing LA provides quantitative data by comparing signal abundances of sodium from tissues to those obtained by imaging quantitation calibration standards of the target element applied to adjacent control tissue sections.

Ultrasensitive Detection of Low-Abundance Protein Biomarkers by Mass Spectrometry Signal Amplification Assay.

A mass spectrometry signal amplification method is developed for the ultrasensitive and selective detection of low-abundance protein biomarkers by utilizing tag molecules on gold nanoparticles (AuNPs). EpCAM and thrombin as model targets are captured by specific aptamers immobilized on the AuNPs. With laser desorption/ionization time-of-flight mass spectrometry (LDI-TOF MS), the mass tag molecules are detected to represent the protein biomarkers.

Porous silica enhanced proteolysis during Off-Gel separation for efficient protein identification.

An advanced approach is developed in this work for simultaneous on-line separation and digestion of proteins by combining the Off-Gel isoelectric focusing (IEF) and enzymatic nanoreactor enhanced proteolysis. The nanoreactor was prepared by preloading trypsin in amino-functionalized macroporous silica, and then directly added into Off-Gel wells. With the nanoreactor loaded Off-Gel device, effective digestion of proteins happened during IEF electrophoresis to generate directly fractionated tryptic peptides, which not only accelerated the experimental flow but also avoided sample loss, leading to a more comprehensive protein identification from complex biological samples.

Designer SiO₂@Au nanoshells towards sensitive and selective detection of small molecules in laser desorption ionization mass spectrometry.

Unlabelled: We report a novel platform using optimized SiO2@Au core-shell structures as matrices for highly efficient laser desorption/ionization mass spectrometry analysis of small biomolecules (MW<700 Da). Owing to the designer structure, SiO2@Au nanoshells can achieve low detection-of-limits (~pmol-fmol) in mass spectrometry and selective laser desorption/ionization in bio-mixtures towards diverse small molecules. By further surface modification with aptamers, Apt-SiO2@Au nanoshells allowed simultaneously targeted enrichment and detection of kanamycin with a detection limit at 200 pM.

Amino-functionalized macroporous silica for efficient tryptic digestion in acidic solutions.

Amino-functionalized macroporous silica foam (NH2 -MOSF) has been developed as a host reactor to realize highly efficient proteolysis in acidic solutions where normal tryptic reactions cannot occur. The digestion protocol consists simply of adding the functionalized NH2 -MOSF into the protein and trypsin solutions without altering the bulk pH or preloading the enzymes on the materials. With this protocol, digestion of sample fractions from LC can be efficiently realized in the acidic solutions directly.

Periodic mesoporous organosilica as a multifunctional nanodevice for large-scale characterization of membrane proteins.

A versatile protocol has been developed for large-scale characterization of hydrophobic membrane proteins based on the periodic mesoporous organosilica (PMO) acting as both an extractor for hydrophobic substrate capture and a nanoreactor for efficient in situ digestion. With introduction of organic groups in the pore frameworks and the presence of hydrophilic silanol groups on the surface, PMO can be well-dispersed into not only an organic solution to concentrate the dissolved membrane proteins but also an aqueous solution containing enzymes for sequential rapid proteolysis in the nanopores. The unique amphiphilic property of PMO ensures a facile switch in different solutions to realize the processes of substrate dissolution, enrichment, and digestion effectively.

Label-free fluorescent sensor for mercury(II) ion by using carbon nanotubes to reduce background signal.

A simple, selective and sensitive turn-on fluorescent sensor for the detection of mercury(II) ion was developed using Sybr Green I as the signal reporter and SWCNTs as the quencher. Due to the affinity of SWCNTs towards ssDNA and organic dye, Sybr Green I, thymine-rich ssDNA and SWCNTs could form a self-assembly of three components, resulting in fluorescence quenching. Upon addition of another thymine-rich ssDNA and mercury(II) ion, formation of dsDNA via T-Hg(2+)-T base pairs enabled Sybr Green I to intercalate into the dsDNA, resulting in the restoration of fluorescence.