Graphene Biosensor Programming with Genetically Engineered Fusion Protein Monolayers

Abstract

We demonstrate a label-free biosensor concept based on specific receptor modules, which provide immobilization and selectivity to the desired analyte molecules, and on charge sensing with a graphene field effect transistor. The receptor modules are fusion proteins in which small hydrophobin proteins act as the anchor to immobilize the receptor moiety. The functionalization of the graphene sensor is a single-step process based on directed self-assembly of the receptor modules on a hydrophobic surface. The modules are produced separately in fungi or plants and purified before use. The modules form a dense and well-oriented monolayer on the graphene transistor channel and the receptor module monolayer can be removed, and a new module monolayer with a different selectivity can be assembled in situ. The receptor module monolayers survive drying, showing that the functionalized devices can be stored and have a reasonable shelf life. The sensor is tested with small charged peptides and large immunoglobulin molecules. The measured sensitivities are in the femtomolar range, and the response is relatively fast, of the order of one second.

In‐solution antibody harvesting with a plant‐produced hydrophobin–Protein A fusion

“…However, the applications are not limited to that. Recently, the surface-active and self-assembling properties of HFBs and HFB fusion proteins have been utilized for example in functional coatings of nanoparticles and surfaces (Soikkeli et al, 2016;Sarparanta et al, 2012;Kurppa et al, 2014). With the emerging interest in material technology, HFBs can be seen as very interesting building blocks for a host of novel fusion proteins.…”

Evaluating the potential of natural surfactants in the petroleum industry: the case of hydrophobins

“…The good surface activity and exceptionally high surface elasticity of HFBs makes them the most surface-active proteins currently known, which promoted their successful Brought to you by | MIT Libraries Authenticated Download Date | 5/12/18 9:00 AM exploitation in several different fields. Some of the uses proposed for HFBs include stabilization of foams and emulsions in the food industry [16], biotechnological applications such as drug delivery [17,18], biomedical imaging [19] and coatings for biomedical devices [20], but also use as dispersing agents [21,22] and intermediates for surface immobilization of proteins [23,24] and polymers [25]. The ability of HFBs to self-assemble at oil-water interfaces and stabilize oil droplets makes them potential candidates for a more efficient and greener EOR strategy, also in consideration of the fact that the potential for large scale production of these proteins has been shown in industrial operations for both classes of HFBs [14,16].…”

Bioreducible Hydrophobin-Stabilized Supraparticles for Selective Intracellular Release

“…The applicability of the developed methodology is general and may be applied to the obtainment of a broad variety of new SPs, for example, fluorinated ones. Furthermore, the possibility to modify chemically or genetically, that is, fusion proteins, 53 the HFBII shell allows for further functionalization of the SP surface for targeting specific tissues. Overall, these results are important for guiding advances in the design of multistage and multimodal nanosystems for diagnosis and therapy.…”