Single-Cell Protein Assays: A Review

Hollow Cathode Discharge Ionization Mass Spectrometry: Detection, Quantification and Gas Phase Ion-Molecule Reactions of Explosives and Related Compounds

Mass spectrometry (MS) has become an essential analytical method in every sector of science and technology. Because of its unique ability to provide direct molecular structure information on analytes, an extra method is rarely required. This review describes fabrication of a variable-pressure hollow cathode discharge (HCD) ion source for MS in detection, quantification and investigation of gas-phase ion molecule reactions of explosives and related compounds using air as a carrier gas. The HCD ion source has been designed in such a way that by altering the ion source pressures, the system can generate both HCD and conventional GD. This design enables for the selective detection and quantification of explosives at trace to ultra-trace levels. The pressure-dependent HCD ion source has also been used to investigate ion-molecule reactions in the gas phase of explosives and related compounds. The mechanism of ion formation in explosive reactions is also discussed.

Manipulation of living cells with 450 nm laser photobiomodulation

Increasing studies demonstrated that photobiomodulation (PBM) influenced specific biological effects in cells, tissues and organs, and these effects rely on the production of light irradiation. In this study, we aimed to precisely manipulate the spatial arrangement of adhesion cells in a traditional culture condition with 450 nm low intensity laser. Through 450 nm laser PBM, the adhesion of the cultured cells was significantly improved and resisted the digestion of 0.1% trypsin. Combined with a computer aided design system (CAD) and computer numerical control (CNC) system, the designed laser irradiation pattern induced the specific cell micropattern in the culture dish. RNA sequencing and biochemical experiments confirmed that the 450 nm laser prompted low-density lipoprotein (LDL) bonding to the cell surface and induced lipid peroxidation, which crosslinked and modified the protein molecules on the irradiated cell surface. In this way, the peroxidation product-modified proteins resisted trypsin proteolysis, ultimately leading to a differential detachment between the irradiated and non-irradiated cells under trypsin treatment. This convenient method did not require special biomaterial processing, has no impact on cell viability and functions, and required no changes to the conventional cell culture conditions. The photo-induced cell capturing is a great complement to existing tools by providing spatial resolution.