Hierarchical Nanotextured Microelectrodes Overcome the Molecular Transport Barrier To Achieve Rapid, Direct Bacterial Detection

Abstract

Detection of biomolecules at low abundances is crucial to the rapid diagnosis of disease. Impressive sensitivities, typically measured with small model analytes, have been obtained with a variety of nano- and microscale sensors. A remaining challenge, however, is the rapid detection of large native biomolecules in real biological samples. Here we develop and investigate a sensor system that directly addresses the source of this challenge: the slow diffusion of large biomolecules traveling through solution to fixed sensors, and inefficient complexation of target molecules with immobilized probes. We engineer arrayed sensors on two distinct length scales: a ∼100 μm length scale commensurable with the distance bacterial mRNA can travel in the 30 min sample-to-answer duration urgently required in point-of-need diagnostic applications; and the nanometer length scale we prove necessary for efficient target capture. We challenge the specificity of our hierarchical nanotextured microsensors using crude bacterial lysates and document the first electronic chip to sense trace levels of bacteria in under 30 min.

Solution-based circuits enable rapid and multiplexed pathogen detection

“…Many applications in infectious disease testingincluding testing of swab samples for health-care-associated infections or sexually transmitted infections, or the testing of urine for infectious pathogens-yield samples that contain concentrations higher than 1 cfu ml À 1 . This detection and speed combination also approaches the diffusional limits for large molecules in static solutions 30 .…”

“…By restricting growth within these apertures, we then grew micron-sized tree-like electrodes via electrodeposition, resulting in nanostructured microelectrodes that protrude from the surface and reach into solution. It was previously shown that the micron-sized scale of the protruding electrodes increases the cross-section for interaction with analyte molecules 30 , whereas the nanostructuring maximizes sensitivity by enhancing hybridization efficiency between tethered probe and the analyte in solution 31 . Here these structures are being used to enable the creation of layered, insulated electrode arrays (Fig.…”

Complex epsilon-near-zero metamaterials for broadband light harvesting systems

“…It is therefore important to develop a fabrication technique whereby disorder can be produced on large scales and with controllable features. In order to assemble a broadband ENZ nanomaterial, we used an electroplating process that grows a random networks of gold (Au) nanowires from a flat metallic Au substrate [32][33][34][35] (Figure 1). Figure 2a shows SEM cross sections of a fabricated sample.…”

Electrochemical nanosensors: advances and applications

“…31 Nanoelectrode devices offer an attractive option in this field due to their small footprint and potential for high sensitivity. As a result of the versatility and variety of nanoelectrode devices, they have been employed for the detection of a large range of medically relevant analytes ranging from small molecules such as dopamine [32][33][34] and histamine 35 to larger, more complex targets like bacteria 36 or pharmaceutical drugs. 37,38 Enzyme based biosensors have long been of interest because of the selectivity of enzymes as biorecognition elements.…”