Several studies have been published on the substantivity and penetration of fluorescein isothiocyanate (FITC)-labeled proteins and protein hydrolyzates into human hair using fluorescence microscopy1, 2 or confocal laser scanning fluorescence microscopy.3, 4 The latter method provides a new dimension of hair fiber observation and diagnostic perspective, as will be shown, due to its significantly higher resolution than classical microscopy, which locates penetrated labeled proteins more precisely.
Lab Practical: Using Fluorescence Laser Scanning Confocal Microscopy
- A high performance fluorescence laser scanning confocal microscope and an experienced operator are required to perform comparable examinations.
- The purification step after FITC labeling of substances to be analyzed is critical. The correct separation of unreacted label, i.e. FITC, from labeled molecules using e.g. chromatography is a prerequisite for further analysis.
- Researchers are urged to take a rigorous approach to the treatment conditions and uniformity of treatment procedures.
- There is significant background fluorescence in hair, thus it is important to always use the same conditions for a comparable series of image acquisitions.
- An optimum equilibrium of laser power for correct imaging without bleaching the label is necessary.