Biosensor stabilization using hypersolutes

Introduction A biosensor may be described as a sensor incorporating a biological element such as an enzyme, antibody, nucleic acid, microorganism or cell. A biosensor should exhibit both shelf-stability and operation stability. Compatible solutes from hyperthermophilic bacteria, called hypersolutes, are very efficient for the preservation of the performance of a wide variety of biomaterials; ranging from proteins to whole cells and artificial tissues. The overall objectives of this work have been to investigate the application of hypersolutes to enhance the performance of biosensors based on the stabilization properties offered by hypersolutes compounds, particularly with respect to storage and operational lifetime. Materials and Methods The stabilizing agents considered for this study were firoin, firoin A, ectoine®, hydroxyectoine, diglycerol phosphate (DGP) and potassium mannosyl-lactate (PML), provided either by Bitop AG (Witten, D) or StabVida (Oeiras, P).The following enzymes were selected due to their commercial importance: Glucose oxidase (GOx), alcohol oxidase (AOx), acetylcholinesterase (AchE) and lactate dehydrogenase (LDH). On immunosensors, a model system was first designed using ELISA tests. The influence of hypersolutes was then studied using BIAcore. The antibody test system selected for examination of the effect of stabilizing agents on immunosensor performance was based on an anti-human immunoglobulin G (IgG) primary antibody, grown in goat, and an anti-goat secondary antibody conjugated to horseradish peroxidase enzyme. A model DNA binding system was sought: The poly-A strand was tethered to the sensing surface within the BIAcore system via a biotin-streptavidin linkage whereas the complimentary poly-T strand contained a fluorescent Cy3 label, that offered the possibility to also use more conventional detection techniques to ensure thathybridization between the two complimentary strands had been achieved, as well as add a significant weight to the strand, increasing its visibility on the BIAcore signal.