Cellular Metabolomics by a Universal Redox-Reactive Nanosensors Array: From the Cell Level to Tumor-on-a-Chip Analysis

Abstract

Although biosensors based on nanowires-field effect transistor were proved extraordinarily efficient in fundamental applications, screening of charges due to the high-ionic strength of most physiological solutions imposes severe limitations in the design of smart, “real-time” sensors, as the biosample solution has to be previously desalted. This work describes the development of a novel nanowire biosensor that performs extracellular real-time multiplex sensing of small molecular metabolites, the true indicators of the body’s chemistry machinery, without any preprocessing of the biosample. Unlike other nanoFET devices that follow direct binding of analytes to their surfaces, our nanodevice acts by sensing the oxidation state of redox-reactive chemical species bound to its surface. The device’s surface array is chemically modified with a reversible redox molecular system that is sensitive to H2O2 down to 100 nM, coupled with a suite of corresponding oxidase enzymes that convert target metabolites to H2O2, enabling the direct prompt analysis of complex biosamples. This modality was successfully demonstrated for the real-time monitoring of cancer cell samples’ metabolic activity and evaluating chemotherapeutic treatment options for cancer. This distinctive system displays ultrasensitive, selective, noninvasive, multiplex, real-time, label-free, and low-cost sensing of small molecular metabolites in ultrasmall volumes of complex biosamples, in the single-microliter scale, placing our technology at the forefront of this cutting-edge field.

Real-time Monitoring of Bacterial Biofilms Metabolic Activity by a Redox-Reactive Nanosensors Array

“…Based on the fact that the reaction of speci c oxidase enzymes of target metabolites produce , surface modi cation of an active redox system composed of 9,10-dihydroxyanthracene/9,10-anthraquinone (DHA/AQ) was chosen [13]. This layer of an active redox system alternates from oxidized to reduced states and contributes charge carriers which are followed by electrical changes on the surface of the SiNW FET.…”

“…This layer of an active redox system alternates from oxidized to reduced states and contributes charge carriers which are followed by electrical changes on the surface of the SiNW FET. Moreover, SiNW FETs modi ed with active redox systems enable the monitoring of metabolites without any preprocessing of the sample [13,27], including desalting, directly from the extracellular medium of the bacterial bio lm, and offer the reuse of the nanosensor because of the unique reversible redox system. Detection and monitoring of the extracellular composition of bacterial bio lm have a considerable advantage since it is much easier to detect changes in metabolite concentrations extracellularly, as the device does not have to be in contact with the bio lm (Figure 1a right panel).…”

“…More speci cally, the inhibition of bacterial metabolism of glucose consumption can be used as an index of bacterial susceptibility to drugs [43,44]. A unique redox-reactive modi cation on the surface of the SiNW FET devices was previously shown to be a powerful tool for glucose sensing in high-ionic-strength solution [13,27]. The redox system's functional group comprising 9,10-dihydroxyanthracene (AQ), that can be oxidized or reduced in a reversible manner, which involves a signi cant change in the charge [13,45], and in uences the conductivity of the FET.…”

“…A unique redox-reactive modi cation on the surface of the SiNW FET devices was previously shown to be a powerful tool for glucose sensing in high-ionic-strength solution [13,27]. The redox system's functional group comprising 9,10-dihydroxyanthracene (AQ), that can be oxidized or reduced in a reversible manner, which involves a signi cant change in the charge [13,45], and in uences the conductivity of the FET. Hydrogen peroxide (H 2 O 2 ) is an oxidative species that can selectively react with the redox modi cation and change the level of oxidation of the system.…”

“…Hydrogen peroxide (H 2 O 2 ) is an oxidative species that can selectively react with the redox modi cation and change the level of oxidation of the system. Moreover, hydrogen peroxide has been used in a technique for real-time monitoring of metabolites by the use of corresponding oxidase enzymes to convert target metabolites to H 2 O 2 [13]. This platform was coupled with micro uidic technologies that allowed the delivery of small volumes of detected samples on the surface of the nanosensor.…”