The biological properties of chitosans have been explored for many years in various applications for which the cationic nature of these polysaccharides is essential. In this presentation, three topics will be discussed related to intermolecular interactions responsible for chitosan activity. In the first, results will be presented about the interaction of distinct types of chitosan with cell membrane models represented by Langmuir monolayers. Parameters such as molecular weight and hydrophobicity are found to govern the interaction leading to the antimicrobial property of chitosans, in addition to the obvious electrostatic attraction between the positively charged chitosans and negatively charged monolayers mimicking bacterial membranes. A comparison of bactericide activities of derivatized chitosans is the focus of the second topic, from which one infers that the availability of charged amine groups is the most relevant factor to determine activity. In the third topic, examples will be provided of the cationic nature of chitosans being exploited to produce layer-by-layer (LbL) films used in biosensing. In this type of application, chitosans can be used as active layers in electronic tongues or as matrix for immobilization of antibodies in biosensors to detect cancer biomarkers. In common in the three topics is the need to understand molecular-level interactions not only to explain chitosan activity but also to design new devices and applications.

Chitosans in nanostructured films for biosensing and antimicrobial coatings

253rd National Meeting (2017)

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