Modeling of Intrinsic Noise in Adsorption-Based Micro/Nanobiosensors Considering Biomolecular Rearrangement on the Sensing Surface

Sensing of biomolecules is often based on their adsorption on the sensitive surface of the sensor. Some types of biomolecules undergo changes in their spatial configuration, i.e. rearrangement, when interacting with the sensing surface. It is known that biomolecular rearrangement can significantly change the kinetics of sensor response. However, the influence of this phenomenon on sensor noise has not been investigated so far. The noise of the sensor determines its performance limits, and it can also be a source of information about the biomolecular quantity in the analyzed sample, as well as biomolecular interactions. Since the intrinsic noise originating from fluctuations of the number of the adsorbed molecules is pronounced in micro/nanobiosensors, it is useful to develop a noise model that includes all processes that affect the random change of the adsorbed amount. Such a model is essential for reliable biomolecular detection and quantification by using noise-based methods. In this paper, we present the first model of sensor intrinsic noise which, in addition to the adsorption-desorption process, also takes into account biomolecular rearrangement. Then we analyze the influence of rearrangement processes for different values of their rate constants. The obtained results show the dependence of characteristic features of the noise spectral density on the rate of conversion of adsorbed molecules from one configuration to another.