Antibiotic resistance-related infections lead to around 700 000 deaths each year. Unfortunately, the development of new antibiotics is too slow to address the alarming growth of bacterial resistance. The challenge then lies in developing new drugs to achieve high therapeutic activity while optimizing affinity and selectivity towards a target. In this context, the aptamers associated with antimicrobial peptides (AMPs) vectorized by a silica nanoparticle appears as an innovative solution. Aptamers are simple DNA or RNA sequences selected by SELEX procedures. They can specifically recognize a target with a high affinity and specificity. Compared to antibodies, the main advantages of aptamers are the following: non-immunogenic, small, chemically produced therefore easily modified with a dye or a functional group as well as low variability between batches. AMPs, which are synthetic or natural protein molecules with antibiotic properties, are a promising class of anti-infective agents. The combination of these two key elements in a vector such as a nanoparticle will allow to target and eliminate efficiently the bacterium strain of interest. The first objective of this project is to characterize an aptamer sequence able to bind specifically a bacterial strain. To achieve this, the analysis technique used to detect these interactions is flow cytometry. The main asset of this method is its rapid and direct detection, also the sample can be analysed immediately after incubation without treatment. By using a set of fluorophore-tagged aptamers (previously isolated by research groups), it was possible to discriminate bacteria capable of interacting through molecular patterns present on their surfaces. Many assays were carried out by varying several parameters: the concentration of aptamer and bacteria, the nature of the buffer, the temperature, and the incubation time to find the optimal conditions to obtain the best interaction.