Abstract
Proper hydration of the stratum corneum, the skin’s outermost layer, is essential for healthy skin. Water-soluble substances called natural moisturizing factors (NMF) are responsible for maintaining adequate moisture in the skin and are closely associated with a variety of the skin’s functions. Therefore, quantitative analysis methods for NMF are indispensable when attempting to clarify one of the mechanisms of hydration and its effect on the skin. This study sought to develop a quick and simple analytical technique, which can quantify NMF from the skin without the need for extraction or separation, using direct analysis in real time-mass spectrometry (DART-MS). The goal was to deliver a high quantitative capability, so a unique inkjet printing technique was employed to evenly coat a stable isotope-labeled internal standard (SIL-IS) on tape-stripped skin. This technique allowed for the quantification of 26 NMF with established calibration curves and comparatively high linear correlations. The speed of measurement was found to be advantageous as 100 strips of tape can be measured in roughly 2 hours. The effectiveness of the inkjet coating was also verified by comparing its precision with that of conventional pipetting. This new technique can be an alternative method to quantify NMF rapidly and perhaps allow for a clearer elucidation of their function in skin.
Highlights
Www.nature.com/scientificreports in some diseases, such as ichthyosis and atopic dermatitis[43,44]
Since the amount of total proteins measured is considered to be proportional to the amount of SC removed, that value was used to normalize the amount of natural moisturizing factors (NMF) measured using DART-MS21
multiple reaction monitoring (MRM) chromatograms measured with optimized MRM methods for each NMF were produced, and the peak area was used to determine the amount of NMF. 10 tapes are measured at one time within about 10 minutes
Summary
Www.nature.com/scientificreports in some diseases, such as ichthyosis and atopic dermatitis[43,44]. Leucine and isoleucine were not separable without chromatographic techniques. SIL-IS are thought to be essential for quantitative analysis, they are difficult to coat evenly as the SC samples are solid. Leucine and isoleucine have the same molecular composition They cannot be distinguished without chromatographic separation. The product ions induced by collision-induced dissociation are different They can be separated in an identical fashion using TQ. An inkjet printing technique was used to realize homogeneous deposition and coating of the SC samples to improve the accuracy. This technique has been already utilized in the field of imaging MS (IMS) for matrix additions[48], calibration standards[49], and SIL-IS50. Introduced is a novel procedure for high-throughput and quantitative analysis using DART-MS
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