Effects of Iontophoresis, Hydration, and Permeation Enhancers on Human Nail Plate: Infrared and Impedance Spectroscopy Assessment

Abstract

Infrared and impedance spectroscopies were used to investigate the effects of hydration, iontophoresis and chemical enhancer (N-acetyl-L-cysteine) treatment on the healthy human nail.Although significant shifts to higher wavenumbers were observed for the symmetric and asymmetric -CH 2 stretching vibrations, the fact that these changes were essentially the same for the three treatments suggested that they were principally due to hydration alone. Spectral changes associated with amide bonds from nail protein were particularly evident post-treatment with Nacetyl-L-cysteine. The alternating current conductivity and permittivity of the nail, particularly at low frequencies, increased with hydration. Iontophoresis increased the low frequency ac conductivity of the nail but had less effect on the nail capacitance/permittivity. Further, the effects seemed to return gradually to baseline after termination of current passage. Treatment with N-acetyl-L-cysteine produced a greater perturbation, leading to increased low-frequency conductivity and a shift of the frequency-dependent conductivity region to a higher frequency. Overall, the effects of iontophoresis on both the IR and impedance spectroscopic profiles of the nail were attributable simply to increased hydration and similar to those observed after skin iontophoresis. In contrast, both spectroscopy techniques indicated that N-acetyl-L-cysteine disrupted nail structure in line with the enhancer's known effect on keratin.

Constant Voltage Iontophoresis Technique to Deliver Terbinafine via Transungual Delivery System: Formulation Optimization Using Box–Behnken Design and In Vitro Evaluation

“…In both cases, the surface cells seem to be close, did not show much disruption (though few apertures were visible), and have not altered the overall integrity of the nail structure. Indeed, the results here signify that the low voltage iontophoresis did not alter the structure of the nail, which is also in agreement with the general observation in constant current iontophoresis [ 62 ].…”

Influence of water and temperature on the electrical conductivity of the human nail

“…All these graphs in the full frequency range show that the dielectric parameters for wet samples are higher compared to dry samples. In other studies performed with the use of capacitive contact imaging [10] and electrical impedance spectroscopy [12], an increase in the dielectric properties of the nail was also observed along with the increase in the water content in this tissue. As a result of the presence of loosely bound water in a wet nail, two relaxation frequencies f c around 2 and 25 kHz (Fig.…”

“…The results of our previous dielectric studies of the nail [4][5][6][7] indicate the key role of water in protecting the ordered crystalline structure of the keratin molecule before the onset of the melting process. In recent years, nails research also deals with the influence of water on the biophysical and chemical structure of this material [8][9][10][11][12].…”

Transungual permeation: current insights

“…Benzeval et al [66] studied the changes in the IR spectra of nail clippings caused by iontophoresis, N-acetyl-L-cysteine treatment, and hydration. It was observed that with hydration, iontophoresis, and N-acetylcysteine, each of them increased the -CH2 stretching frequencies.…”