We established a procedure to develop a localized surface plasmon resonance (LSPR) optical sensor platform for immunoassay. Computational simulations, focused on the assessment of the LSPR spectrum and spatial distribution of the electromagnetic field enhancement near the metallic nanoparticle, were used to engineer a nanostructured-sensing platform. Crucial parameters that rule the LSPR sensor performance, as bulk and molecular sensitivity, were evaluated, guiding the development of the optical platform. An LSPR surface-based platform composed of silver nanospheres adhered on a glass slide and functionalized with monoclonal anti-Candida antibodies of the IgG class was fabricated. Molecular biosensing was demonstrated by the identification of Candida albicans antigen. In particular, C. albicans is the most common species involved in a variety of hospital yeast infections. The developed sensing platform was able to identify C. albicans antigen concentration as low as 50 ng / mL, indicating the viability of exploring LSPR effect on C. albicans antigen biosensor. Moreover, this work provides insight on the LSPR behavior due to the adsorption of molecules layer on a nanoparticle surface, establishing a paradigm on engineering LSPR biosensor.