Considerable studies have been conducted in the imaging of living cells, using visualization tools based on fluorescent markers. The present work is focused on the synthesis of CdS and ZnS nanocrystals, by a two-phase technique. Nanocrystals were synthesized in water, coated with a suitable surfactant and mobilized into an organic phase before getting aggregated. UV-Vis and PL measurements indicate the formation of CdS and ZnS nanocrystals with an estimated size around 2.4 nm.