Computational Design of Chemical Sensors: from molecules to molecularly imprinted polymers

Abstract

Computational methods can be employed at various stages in the development of different types of chemical sensors. The use of theoretical tools can drastically accelerate the development process of new sensors, as well as helping to obtain a more robust, cheaper, and selective end product. This thesis discusses the employment of different computational chemistry methods in the design of chemical sensors. The first approach deals with the study of electrochemical sensors. Initially, the density functional theory (DFT) method was employed to perform the design of a molecularly imprinted polymer (MIP) for detection of the drug of abuse MDMA. This theoretical method was used to simulate several steps in the synthesis of a MIP in addition to selectivity tests. The set of computational analyses obtained constitutes a very useful protocol to predict the optimal experimental conditions, saving time and financial resources in the process. Still in the electrochemical sensors approach, an electrochemical sensor based on the same MIP technology was developed for detection of progesterone and 17-β Estradiol. The developed material responded to the concentrations of the analytes in the ranges from 10 to 50 μM, and also has a single current range response, which improves the selectivity of the material. The second chemical sensor approach addressed in this thesis was spectroscopic probes. In this part, both computational methods based on classical mechanics such as molecular dynamics (MD) and quantum methods such as DFT were employed to explore the photochemical and spectroscopic properties of the ciprofloxacin molecule. From the calculations performed, it was possible to observe the changes that can occur in the UV-Vis, fluorescence and fluorine19 NMR spectra of the antibacterial agent when it interacts with the human topoisomerase-II beta enzyme. Such results indicate a possibility of using ciprofloxacin as a spectroscopic probe for cancer detection, since this enzyme is related to the disease. From all the tests performed, it can be concluded that computational methods are able to predict many properties and behaviors that can be useful in the design of new chemical sensors. The manipulation of molecules and systems in a theoretical way can assist in obtaining crucial information that often cannot be obtained experimentally. Moreover, it is also possible to conclude that chemical sensors are an extremely useful and versatile technology that can be developed for various purposes.