Intact living-cell electrolaunching ionization mass spectrometry for single-cell metabolomics.

While single-cell mass spectrometry can reveal cellular heterogeneity and the molecular mechanisms of intracellular biochemical reactions, its application is limited by the insufficient detection sensitivity resulting from matrix interference and sample dilution. Herein, we propose an intact living-cell electrolaunching ionization mass spectrometry (ILCEI-MS) method. A capillary emitter with a narrow-bore, constant-inner-diameter ensures that the entire living cell enters the MS ion-transfer tube.

Complement-Opsonized NIR-IIb Emissive Immunotracers for Dynamically Monitoring Neutrophils in Inflammation-Related Diseases.

Real-time monitoring of neutrophil dynamics is crucial for timely diagnosis and effective treatment of inflammation-related diseases, which requires a reliable tracer for in vivo tracking of neutrophils. However, immunotracers for neutrophils are extremely limited because of the difficulty in labeling the cells. Inspired by the natural biological function of the complement system, a strategy of enhancing the complement C3 opsonization of lanthanide-doped nanoparticles (LnNPs) by modulating their surface chemistry, thus developing a near infrared-IIb emissive nanotracer for neutrophils, is reported herein.

Analytical methods for obtaining binding parameters of drug-protein interactions: A review.

The study of drug-protein interactions can reveal the corresponding binding mechanisms, providing valuable information for the early phase drug development and development of new drugs. This article reviews the methods used for obtaining the binding parameters of drug-protein systems. The methods include equilibrium dialysis, high-performance affinity chromatography, capillary electrophoresis, spectroscopy, calorimetry, competition and displacement, mass spectrometry, fluorescence resonance energy transfer, and thermal stability shift analysis.

Controllable Fabrication of Small-Size Holding Pipets for the Nondestructive Manipulation of Suspended Living Single Cells.

The capture and manipulation of single cells are an important premise and basis for intracellular delivery, which provides abundant molecular and omics information for biomedical development. However, for intracellular delivery of cargos into/from small-size suspended living single cells, the capture methods are limited by the lack of small-size holding pipets, poor cell activity, and the low spatial accuracy of intracellular delivery. To solve these problems, a method for the controllable fabrication of small-size holding pipets was proposed.

Visually precise, low-damage, single-cell spatial manipulation with single-pixel resolution.

The analysis of single living cells, including intracellular delivery and extraction, is essential for monitoring their dynamic biochemical processes and exploring intracellular heterogeneity. However, owing to the 2D view in bright-field microscopy and optical distortions caused by the cell shape and the variation in the refractive index both inside and around the cells, achieving spatially undistorted imaging for high-precision manipulation within a cell is challenging. Here, an accurate and visual system is developed for single-cell spatial manipulation by correcting the aberration for simultaneous bright-field triple-view imaging.

Solid-phase microextraction integrated nanobiosensors for the serial detection of cytoplasmic dopamine in a single living cell.

Dopamine participates in many physiological and pathological processes. Dynamic monitoring of dopamine levels in the cytoplasm of a single living cell reflects not only the functional state of dopamine synthesis factors but also the processes of related neurodegenerative diseases. Due to the low content of cytoplasmic dopamine and the difficulty to keep cells alive during the operating process, the detection of cytoplasmic dopamine is still challenging.

Controllable fabrication of pico/femtoliter pipette sampling probes and visual sample volume determination.

We propose a hydraulically assisted eddy-current etching method for the controllable fabrication of pico/femtoliter sampling probes with equal inner diameters along the length of the probe. The relative standard deviations of the outer and inner diameters (O.D.

Gas phase reaction between chromones and solvent in an electrospray ionization source.

Chromones were measured by using electrospray ionization mass spectrometry in negative mode. Interestingly, in addition to the deprotonated ion ([M - H] ), unexpected [M + 17] and [M + 31] ions were observed in high intensity when water and methanol were used as the solvent. Chromones with different substitutes were tested.

Loss of benzaldehyde in the fragmentation of protonated benzoylamines: Benzoyl cation as a hydride acceptor in the gas phase.

In electrospray ionization tandem mass spectrometry of protonated 1-benzoylamines (1-benzoylpiperadine, 1-benzoylmorpholine, and 1-benzoyl-4-methylpiperazine), the dominant fragmentation pathway was amide bond cleavage to form benzoyl cation and neutral amine. Meanwhile, in their fragmentations, an interesting loss of benzaldehyde (106 Da) was observed and identified to derive from hydride transfer reaction between the benzoyl cation and amine. A stepwise mechanism for loss of 106 Da (benzene and CO) could be excluded with the aid of deuterium labeling experiment.

Pico-HPLC system integrating an equal inner diameter femtopipette into a 900 nm I.D. porous layer open tubular column.

A picoflow high performance liquid chromatography (pico-HPLC) system was developed, which could directly pipette femtoliter samples using a separation column tip driven by an electroosmotic pump. Amino acid enantiomers were separated in the 900 nm I.D.