We have studied one-dimensional (1D) relief metalized subwavelength gratings, which support resonant optical transmission. We have used pregrooved DVD stampers, metalized with a thin Al layer. The sensitivity of resonant transmission of the gratings to the cladding environment was investigated by the help of matching fluids. We have shown that the shift of the spectral position of the resonance peak can be used for sensor applications, e.g., for determination of very low concentrations of nanosized dielectric particles in distilled water.