Electrospray ionization (ESI) is a mass spectrometric technique widely used in various fields including chemistry, biology, medicine, pharmaceutical industry, clinical assessment, and forensic science. In this study, we report a simple and economical ESI-mass spectrometry (MS) technique, which makes use of disposable wooden tips (wooden toothpicks) for loading and ionization of samples. Samples could be loaded by normal pipetting onto the tip or simply dipping the tip into sample solutions. The hydrophilic and porous nature of wood allows effective adhesion of the sample solution for durable ion signals. The tip can be directly connected to nano-ESI ion sources of various mass spectrometers. Upon application of high voltage to the tip, desirable mass spectra could be obtained. We demostrated that this new technique is applicable for analysis of various samples, including organic compounds, organometallic compounds, peptides, proteins, and samples that cannot be directly analyzed by conventional ESI techniques, e.g., slurry samples and powder samples. The slim and hard properties of the wooden tip enable sampling from specific locations such as corners and small openings, indicating potential applications of the new technique in forensic investigations. The observation of electrospray ionization from wooden materials also allows us to get new insights into the materials that can be directly ionized for mass spectrometric analysis.

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Highlights d Injury-elevated Lipin1 and DGAT in retinal ganglion cells suppress regeneration d Neuronal lipin1 and DGATs increase triglyceride and decrease phospholipids d Redirecting triacylglyceride to phospholipid synthesis promotes axon regeneration

Food production in green crops is severely limited by low activity and poor specificity of D-ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) in natural photosynthesis (NPS). This work presents a scientific solution to overcome this problem by immobilizing RuBisCO into a microfluidic reactor, which demonstrates a continuous production of glucose precursor at 13.8 μmol g −1 RuBisCO min −1 from CO 2 and ribulose-1,5-bisphosphate. Experiments show that the RuBisCO immobilization significantly enhances enzyme stabilities (7.2 folds in storage stability, 6.7 folds in thermal stability), and also improves the reusability (90.4% activity retained after 5 cycles of reuse and 78.5% after 10 cycles). This work mimics the NPS pathway with scalable microreactors for continuous synthesis of glucose precursor using very small amount of RuBisCO. Although still far from industrial production, this work demonstrates artificial synthesis of basic food materials by replicating the light-independent reactions of NPS, which may hold the key to food crisis relief and future space colonization.

A novel method is proposed for rapid identification of viruses and other organisms that show a low number of biomarkers, based on the construction of databases of organism-specific tryptic peptide masses. The peptide products of any protease that cuts at specific residues can be accommodated. Experimentally, a sample of intact virus, e.g., one collected from the atmosphere, is digested with a selective protease for a short time, and the digestion products are analyzed by MALDI-TOF mass spectrometry without fractionation or purification. In the present proof of concept, the Sindbis virus AR 339 was identified by using the masses of observed tryptic peptide products to query a database composed of tryptic peptide masses generated in silico for six viruses whose genomes have been sequenced. Two algorithms were tested for identification--a direct score-ranking algorithm and an algorithm that evaluates the probability of random matching. The Sindbis virus was unambiguously identified by either approach. The influence of factors such as experimental mass accuracy, number of missed cleavages, and database size on the identification algorithms has also been evaluated, with the objective of extending the approach to other microorganisms.