Wearable aptamer-field-effect transistor sensing system for noninvasive cortisol monitoring

Battery-free, tuning circuit-inspired wireless sensor systems for detection of multiple biomarkers in bodily fluids

Tracking the concentration of biomarkers in biofluids can provide crucial information about health status. However, the complexity and nonideal form factors of conventional digital wireless schemes impose challenges in realizing biointegrated, lightweight, and miniaturized sensors. Inspired by the working principle of tuning circuits in radio frequency electronics, this study reports a class of battery-free wireless biochemical sensors: In a resonance circuit, the coupling between a sensing interface and an inductor-capacitor oscillator through a pair of varactor diodes converts a change in electric potential into a modulation in capacitance, resulting in a quantifiable shift of the resonance circuit. Proper design of sensing interfaces with biorecognition elements enables the detection of various biomarkers, including ions, neurotransmitters, and metabolites. Demonstrations of "smart accessories" and miniaturized probes suggest the broad utility of this circuit model. The design concepts and sensing strategies provide a realistic pathway to building biointegrated electronics for wireless biochemical sensing.

Nanoparticle-Mediated Signaling for Aptamer-Based Multiplexed Detection of Cortisol and Neuropeptide Y in Serum

Multiplexed profiling of the expression of neurochemical biomarkers of stress, for periodic assessment to enable augmentation of human performance, requires wash-free detection platforms that exhibit reproducible signals from samples in biological matrices. However, alterations in aptamer conformation after binding to targets, such as cortisol, are minimal based on NMR spectra, and the methylene blue signaling is blocked by serum proteins. Hence, in this study, we explore aptamer derivatization with magnetic nanoparticles that are conjugated with multiple methylene blue moieties, to amplify signals and alter the net charge configuration for repulsing serum proteins, so that the aptamer conformation upon target recognition can lead to a signal ON assay in serum media. Based on this, a microchip platform with addressable electrodes that are immobilized with selective aptamer receptors is developed for multiplexed detection of cortisol (1–700 ng/mL) and neuropeptide Y (5–1000 pg/mL) in patient-derived serum samples, which is validated by immunoassays. We envision the application of this sensor for profiling a wider array of human performance biomarkers under stress-related events to develop stress augmentation methodologies.

Highly sensitive, scalable, and rapid SARS-CoV-2 biosensor based on In2O3 nanoribbon transistors and phosphatase

Developing convenient and accurate SARS-CoV-2 antigen test and serology test is crucial in curbing the global COVID-19 pandemic. In this work, we report an improved indium oxide (In₂O₃) nanoribbon field-effect transistor (FET) biosensor platform detecting both SARS-CoV-2 antigen and antibody. Our FET biosensors, which were fabricated using a scalable and cost-efficient lithography-free process utilizing shadow masks, consist of an In₂O₃ channel and a newly developed stable enzyme reporter. During the biosensing process, the phosphatase enzymatic reaction generated pH change of the solution, which was then detected and converted to electrical signal by our In₂O₃ FETs. The biosensors applied phosphatase as enzyme reporter, which has a much better stability than the widely used urease in FET based biosensors. As proof-of-principle studies, we demonstrate the detection of SARS-CoV-2 spike protein in both phosphate-buffered saline (PBS) buffer and universal transport medium (UTM) (limit of detection [LoD]: 100 fg/mL). Following the SARS-CoV-2 antigen tests, we developed and characterized additional sensors aimed at SARS-CoV-2 IgG antibodies, which is important to trace past infection and vaccination. Our spike protein IgG antibody tests exhibit excellent detection limits in both PBS and human whole blood ((LoD): 1 pg/mL). Our biosensors display similar detection performance in different mediums, demonstrating that our biosensor approach is not limited by Debye screening from salts and can selectively detect biomarkers in physiological fluids. The newly selected enzyme for our platform performs much better performance and longer shelf life which will lead our biosensor platform to be capable for real clinical diagnosis usage.

ELECTRONIC SUPPLEMENTARY MATERIAL

Supplementary material (materials and methods for device fabrication, functionalization of In₂O₃ devices, photographs of the liquid gate measurement setup, mobilities of the nine devices labeled in Fig. 1(b), family curves of I _DS-V _DS with the liquid gate setup and current change after bubbling the substrate solution (current vs. time curve for S1 antigen detection)) is available in the online version of this article at 10.1007/s12274-022-4190-0.

Cushing's Disease Management: Glimpse Into 2051

Major advancements are expected in medicine and healthcare in the 21st century- "Digital Age", mainly due to the application of data technologies and artificial intelligence into healthcare. In this perspective article we share a short story depicting the future Cushings' Disease patient and the postulated diagnostic and management approaches. In the discussion, we explain the advances in recent times which makes this future state plausible. We postulate that endocrinology care will be completely reinvented in the Digital Age.

High resolution voltammetric and field-effect transistor readout of carbon fiber microelectrode biosensors

Rapid and sensitive pH measurements with increased spatiotemporal resolution are imperative to probe neurochemical signals and illuminate brain function. We interfaced carbon fiber microelectrode (CFME) sensors with both fast scan cyclic voltammetry (FSCV) and field-effect transistor (FET) transducers for dynamic pH measurements. The electrochemical oxidation and reduction of functional groups on the surface of CFMEs affect their response over a physiologically relevant pH range. When measured with FET transducers, the sensitivity of the measurements over the measured pH range was found to be (101 ± 18) mV, which exceeded the Nernstian value of 59 mV by approximately 70%. Finally, we validated the functionality of CFMEs as pH sensors with FSCV ex vivo in rat brain coronal slices with exogenously applied solutions of varying pH values indicating that potential in vivo study is feasible.

Highly sensitive CFMEs as a pH sensor in tandem with both FET and FSCV methods having ex vivo sensing capability is demonstrated.