Convenience biosensing approach of lactic acid in stratum corneum for skin care assessment.

BACKGROUND: Lactic acid in the stratum corneum contributes to skin flexibility, making it a useful indicator of skin conditions. It is this useful to devise a simple technique to measure the lactic acid in the stratum corneum. To this aim, a printed chip biosensor was developed to analyze lactic acid in tape stripped (TS) stratum corneum samples. MATERIALS AND METHODS: Lactic acid was extracted from TS stratum corneum samples. A normal lactic acid sensor was prepared by applying lactate oxidase (LOD) to a printed chip. Another lactic acid sensor was prepared using LOD and a mediator osmium polymer immobilized on a printed chip. The amount of lactic acid in the extracted solutions was quantified using either the prepared biosensors or an existing analysis method. RESULTS: The results measured using the normal lactic acid sensor show low correlation with the results measured using an existing analytical method as a comparison, but those of the mediator osmium lactic acid sensor show high correlation. CONCLUSIONS: The amount of lactic acid in samples extracted from the stratum corneum using a simple TS technique can be simply analyzed with high accuracy using a printed chip biosensor.