Instantaneous Response of Bacteria to External Stimuli Monitored by Syringe Spray Mass Spectrometry

Detection of glutathione, cysteine, and homocysteine by online derivatization-based electrospray mass spectrometry

RATIONALE

Electrospray ionization mass spectrometry (ESI-MS) is one of the most popular techniques for obtaining structural information, which is commonly used in bioanalysis and clinical diagnostics. However, for the detection of complicated samples with high reactivities (such as reactive sulfur species, RSS), traditional ESI-MS usually suffers from overlapped and inaccurate signals. In this study, based on the multiphase flow of extractive electrospray ionization (MF-EESI), an ambient MS technique of online derivatization was proposed to detect thiols without any other sample pretreatment.

METHODS

RSS molecules and the derivatization reagent of 4-chloro-7-nitro-1,2,3-benzoxadiazole (NBD-Cl) were introduced into the internal and innermost capillary of the MF-EESI system, respectively. By a high-velocity nebulizing stream of N₂ gas through an external capillary, both flows of innermost biothiols and internal NBD-Cl were electrosprayed and mixed for online reactions. Therefore, the fast derivatization of thiols was used to generate stable ionized derivatives for MS detection.

RESULTS

By evaluating the changes in MS signals before and after the derivatization, the ions of RSS were identified simply and correctly. Without any sample pretreatment, the fast detection of cysteine, homocysteine, and glutathione has been achieved in the complicated samples.

CONCLUSIONS

The present online derivatization-based MF-EESI was successfully used for fast, simple, and accurate detection of biothiols. This presented a potential pathway for the fast identification of thiols in complicated samples.

Nanoantibiotics: Functions and Properties at the Nanoscale to Combat Antibiotic Resistance

One primary mechanism for bacteria developing resistance is frequent exposure to antibiotics. Nanoantibiotics (nAbts) is one of the strategies being explored to counteract the surge of antibiotic resistant bacteria. nAbts are antibiotic molecules encapsulated with engineered nanoparticles (NPs) or artificially synthesized pure antibiotics with a size range of ≤100 nm in at least one dimension. NPs may restore drug efficacy because of their nanoscale functionalities. As carriers and delivery agents, nAbts can reach target sites inside a bacterium by crossing the cell membrane, interfering with cellular components, and damaging metabolic machinery. Nanoscale systems deliver antibiotics at enormous particle number concentrations. The unique size-, shape-, and composition-related properties of nAbts pose multiple simultaneous assaults on bacteria. Resistance of bacteria toward diverse nanoscale conjugates is considerably slower because NPs generate non-biological adverse effects. NPs physically break down bacteria and interfere with critical molecules used in bacterial processes. Genetic mutations from abiotic assault exerted by nAbts are less probable. This paper discusses how to exploit the fundamental physical and chemical properties of NPs to restore the efficacy of conventional antibiotics. We first described the concept of nAbts and explained their importance. We then summarized the critical physicochemical properties of nAbts that can be utilized in manufacturing and designing various nAbts types. nAbts epitomize a potential Trojan horse strategy to circumvent antibiotic resistance mechanisms. The availability of diverse types and multiple targets of nAbts is increasing due to advances in nanotechnology. Studying nanoscale functions and properties may provide an understanding in preventing future outbreaks caused by antibiotic resistance and in developing successful nAbts.