Graphene based field-effect transistor biosensors functionalized using gas-phase synthesized gold nanoparticles

Research has focused on graphene for developing the next generation of label-free biosensors, capable of highly sensitive and specific detection of DNA or other biomolecules. The binding of charged analytes to the one-atom thick layer of graphene can greatly affect its electronic properties. However, graphene is highly chemically inert, thus surface functionalization through chemical treatment is typically necessary to immobilize receptors of the target biological analyte on the graphene. In this work, we use gas-phase synthesized gold nanoparticles (Au NPs) to functionalize and bind a DNA aptamer to the graphene surface. The graphene is employed in a liquid gated field-effect transistor (FET) configuration to detect the hybridization of the complementary DNA strand, as well as the protein streptavidin, at attomolar level (aM, 10−18 mol L−1). The sensor shows a high dynamic detecting range from aM to picomolar (pM) levels (10-18 to 10-12 mol L−1), can discriminate between a complementary strand anda single nucleotide polymorphism (SNP)containing strand, and achieves adetection limit as low as 15aM. The high detection limit suggests that decorating biosensors with Au NPs synthesized from magnetron sputtering inert gas condensing technique is a promising method for biosensor functionalization, particularly for larger-area sensors that employ two-dimensional materials such as graphene

Nano-vault architecture mitigates stress in silicon-based anodes for lithium-ion batteries

Nanomaterials undergoing cyclic swelling-deswelling benefit from inner void spaces that help accommodate significant volumetric changes. Such flexibility, however, typically comes at a price of reduced mechanical stability, which leads to component deterioration and, eventually, failure. Here, we identify an optimised building block for silicon-based lithium-ion battery (LIB) anodes, fabricate it with a ligand- and effluent-free cluster beam deposition method, and investigate its robustness by atomistic computer simulations. A columnar amorphous-silicon film was grown on a tantalum-nanoparticle scaffold due to its shadowing effect. PeakForce quantitative nanomechanical mapping revealed a critical change in mechanical behaviour when columns touched forming a vaulted structure. The resulting maximisation of measured elastic modulus (similar to 120GPa) is ascribed to arch action, a well-known civil engineering concept. The vaulted nanostructure displays a sealed surface resistant to deformation that results in reduced electrode-electrolyte interface and increased Coulombic efficiency. More importantly, its vertical repetition in a double-layered aqueduct-like structure improves both the capacity retention and Coulombic efficiency of the LIB. Lithiation of anodes during cycling of lithium-ion batteries generates stresses that reduce operation lifetime. Here, a composite silicon-based anode with a nanoscale vaulted architecture shows high mechanical stability and electrochemical performance in a lithium-ion battery.Peer reviewe

Non-enzymatic and highly sensitive lactose detection utilizing graphene field-effect transistors

Field-effect transistor (FET) biosensors based on low-dimensional materials are capable of highly sensitive and specific label-free detection of various analytes. In this work, a FET biosensor based on graphene decorated with gold nanoparticles (Au NPs) was fabricated for lactose detection in a liquid-gate measurement configuration. This graphene device is functionalized with a carbohydrate recognition domain (CRD) of the human galectin-3 (hGal-3) protein to detect the presence of lactose from the donor effect of lectin – glycan affinity binding on the graphene. Although the detection of lactose is important because of its ubiquitous presence in food and for disease related applications (lactose intolerance condition), in this work we exploit the lectin/carbohydrate interaction to develop a device that in principle could specifically detect very low concentrations of any carbohydrate. The biosensor achieved an effective response to lactose concentrations over a dynamic range from 1 fM to 1 pM (10−15 to 10−12 mol L−1) with a detection limit of 200 aM, a significant enhancement over previous electrochemical graphene devices. The FET sensor response is also specific to lactose at aM concentrations, indicating the potential of a combined lectin and graphene FET (G-FET) sensor to detect carbohydrates at high sensitivity and specificity for disease diagnosis