Wearable sampling of proteins from human exhaled aerosols for nano-liquid chromatography-tandem mass spectrometry analysis: A pilot study.

RATIONALE: Human exhaled breath usually contains unique proteins that may provide clues to characterize individual physiological activities and many diseases. However, the concentration of exhaled proteins in exhaled breath is extremely low and usually does not reach the detection limits of all online breath mass spectrometry instruments. Therefore, developing a new breath sampler for collecting and characterizing exhaled proteins is important. METHODS: In this study, a new mask-based wearable sampler was developed by fixing metal materials into the inner surface of the KN95 mask. Human exhaled proteins could be directly adsorbed onto the metal material while wearing the mask. After sampling, the collected proteins were eluted, digested, and identified using nano-liquid chromatography-tandem mass spectrometry (nano-LC-MS/MS). RESULTS: The adsorption of exhaled proteins was evaluated, showing that modified gold foil is an effective material for collecting exhaled proteins. Various endogenous proteins were successfully identified from exhaled breath, many of which can be potential biomarkers for disease diagnosis. CONCLUSIONS: By coupling the newly developed mask sampler with nano-LC-MS/MS, human exhaled proteins were successfully collected and identified. Our results show that the mask sampler is wearable, simple, and convenient, and the method is noninvasive for investigating disease diagnosis and human health.

Direct mass spectrometry analysis of biological tissue for diagnosis of thyroid cancer using wooden-tip electrospray ionization.

Direct mass spectrometry (MS) analysis of human tissue at the molecular level could gain insight into biomarker discovery and disease diagnosis. Detecting metabolite profiles of tissue sample play an important role in understanding the pathological properties of disease development. Because the complex matrices in tissue samples, complicated and time-consuming sample preparation processes are usually required by conventional biological and clinical MS methods. Direct MS with ambient ionization technique is a new analytical strategy for direct sample analysis with little sample preparation, and has been proven to be a simple, rapid, and effective analytical tools for direct analysis of biological tissues. In this work, we applied a simple, low-cost, disposable wooden tip (WT) for loading tiny thyroid tissue, and then loading organic solvents to extract biomarkers under electrospray ionization (ESI) condition. Under such WT-ESI, the extract of thyroid was directly sprayed out from wooden tip to MS inlet. In this work, thyroid tissue from normal and cancer parts were analyzed by the established WT-ESI-MS, showing lipids were mainly detectable compounds in thyroid tissue. The MS data of lipids obtained from thyroid tissues were further analyzed with MS/MS experiment and multivariate variable analysis, and the biomarkers of thyroid cancer were also investigated.

Paper-in-Facemask Device for Direct Mass Spectrometry Analysis of Human Respiratory Aerosols and Environmental Exposures via Wearable Continuous-Flow Adsorptive Sampling: A Proof-of-Concept Study.

Facemasks are considered safe and wearable devices that cover the human mouth and nose for filtering exhaled aerosols and inhaled environmental exposures; various chemical and environmental residues thus can remain in facemasks. Therefore, direct analysis of residues in facemasks can be used to investigate the wearer's health and behavior. Here, we developed a simple paper-in-facemask sampling method for adsorbing a wearer's respiratory aerosol and environmental exposures by fixing paper strips at the outside and inside surfaces of facemasks, and the paper strips were then analyzed by paper spray mass spectrometry (PSMS) for directly detecting adsorbed analytes without any sample pretreatment. The applicability of this device was demonstrated by directly analyzing exhaled aerosolized saliva, breath metabolites, and inhalable environmental exposures. The technical aspects, including sampling time, sampling position, paper property, and spray solvent, were investigated. The sampling process was revealed to involve a continuous-flow adsorptive mechanism. These findings motivated us to extend this work and build a wearable sampling device that is capable of simultaneously monitoring both exhaled and inhaled biomarkers in situ to investigate human health and environmental exposure. This work highlights that facemasks are promising platforms for aerosol collection and direct MS analysis, which is expected to be a promising method for monitoring human health, diseases, and behaviors.