Gold nanoparticlesGold nanoparticles (AuNPS) are widely used metallic nanoparticles with unique surface plasmon characteristics. They have applications in biomedicalBiomedical and therapeutic fields. The present study aims to study the effect of AuNPS chirality surface on the dielectricDielectrics constant, electrical conductivityElectrical conductivity, and antimicrobial activityAntimicrobial activity. AuNPs were prepared using green synthesis with Pirul’s aqueous extract. The modification of chirality is carried out by adding L or D-cysteine to the surface and corroborating it through a chirality analysis. TEM characterized the AuNPs to determine their size and morphology, and the particle size dispersion was evaluated by DLS, Z potential, and electrical parameters were obtained with a precision component analyzer. The disk technique and the MIC and MBC against microorganisms with medical importance were evaluated for microbiological activity. AuNPs with different morphologies (spherical, triangular, and hexagonal) and diameters between 10 and 20 nm were obtained. The diameter increased by 3–4 nm after surface functionalization, while the morphologies remained similar. The functionalization of the surface was verified through a chirality study, observing that the cysteine adhered to the surface, giving them L or D chirality. It was also confirmed that the functional groups of the cysteine and the extract are present on the surface with the help of an IR analysis. AuNPs present strong dielectricDielectrics dispersion corresponding to the alpha relaxation region, and the conductivity values are dependent on the size of the particles; this parameter can be related to a major accumulation and better activity in cells. It was found that the change in chirality affects the antimicrobial properties of the particles since when modifying to a chirality D, the activity decreases. At the same time, L increases by up to 30% and allows antifungal activity against C. albicans. The functionalization of green gold nanoparticlesGold nanoparticles was achieved by changing their chirality by adding the cysteine in its L or D conformation; these changes impact the electrical properties and antimicrobial activityAntimicrobial activity, increasing or decreasing it according to the chirality obtained.