Molecular recognition is key to many biological applications, including biosensing. Yet, little is known about the actual molecular forces behind such recognition, which has motivated intensive research into theoretical and experimental methods that can probe interactions with biomolecules. In this presentation, results will be reported of the use of surface-specific techniques to address several issues associated with biosensing [1]. With sum-frequency generation (SFG) spectroscopy, for example, one may correlate detection of lactose with a sensing unit containing galactosidase to changes in this enzyme structuring in a layer-by-layer (LbL) film [2]. SFG is also suitable to study the organization of adsorbed water at interfaces during sensing experiments. Polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS) is another useful method which can be used to monitor formation of supramolecular structures in sensing devices, in addition to adsorption of analytes [3]. The adhesion force between a functionalized atomic force microscopy (AFM) tip and an analyte adsorbed on a solid support can be determined experimentally with force curves obtained with atomic force spectroscopy (AFS). The measured values for an enzyme attached to an AFM tip could be compared with the theoretical adhesion force estimated using steered molecular dynamics [4], and this can be applied to design novel nanobiosensors. A discussion will also be presented on how manipulation of nanomaterials can be combined with computational methods to exploit biosensors for clinical diagnostics [5]. [1] D. Volpati et. al., Adv. Coll. Interface Sci. 207, 199–215 (2014). [2] P.P. Campos et al., ACS Appl. Mat. Interfaces, 6, 11657−11664 (2014). [3] J.C. Soares et al.; Controlling supramolecular architectures in nanostructured films for detecting breast cancer (in preparation). [4] A.M. Amarante et al., J. Molecular Graphics and Modelling 53, 100–104 (2014). [5] O.N. Oliveira Jr. et al., ACS Appl. Mater. Interfaces, 6, 14745−14766 (2014).

Use of surface-specific spectroscopy techniques to unravel molecular recognition in biosensing

249th National Meeting (2015)

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