In this contribution electromagnetic properties of traditional and modified bow-tie nanoparticles are investigated. The modified bow-tie particles consist of a pair of opposing metallic truncated triangles, embedded in a dielectric environment, with a rectangular dielectric hole engraved on the metallic structure. New analytical models for both structures are developed in order to describe the nanoparticles electromagnetic behavior in terms of resonant wavelength position, magnitude and amplitude width for the extinction cross-section. Analytical results are compared to the numerical values and to the experimental ones existing in literature. Good agreement among them is obtained. Then, the structures are analyzed in terms of sensitivity properties. Results reveal that the modified bow-tie structure can be applied for biomedical applications.