We present a portable non-invasive approach for measuring indicators of inflammation and oxidative stress in the respiratory tract by quantifying a biomarker in exhaled breath condensate(EBC).We discuss the fabricatio...We present a portable non-invasive approach for measuring indicators of inflammation and oxidative stress in the respiratory tract by quantifying a biomarker in exhaled breath condensate(EBC).We discuss the fabrication and characterization of a miniaturized electrochemical sensor for detecting nitrite content in EBC using reduced graphene oxide.The nitrite content in EBC has been demonstrated to be a promising biomarker of inflammation in the respiratory tract,particularly in asthma.We utilized the unique properties of reduced graphene oxide(rGO);specifically,the material is resilient to corrosion while exhibiting rapid electron transfer with electrolytes,thus allowing for highly sensitive electrochemical detection with minimal fouling.Our rGO sensor was housed in an electrochemical cell fabricated from polydimethyl siloxane(PDMS),which was necessary to analyze small EBC sample volumes.The sensor is capable of detecting nitrite at a low over-potential of 0.7 V with respect to an Ag/AgCl reference electrode.We characterized the performance of the sensors using standard nitrite/buffer solutions,nitrite spiked into EBC,and clinical EBC samples.The sensor demonstrated a sensitivity of 0.21μAμM^(−1) cm^(−2) in the range of 20–100μM and of 0.1μAμM^(−1) cm^(−2) in the range of 100–1000μM nitrite concentration and exhibited a low detection limit of 830 nM in the EBC matrix.To benchmark our platform,we tested our sensors using seven pre-characterized clinical EBC samples with concentrations ranging between 0.14 and 6.5μM.This enzyme-free and label-free method of detecting biomarkers in EBC can pave the way for the development of portable breath analyzers for diagnosing and managing changes in respiratory inflammation and disease.展开更多
Microbubbles acting as lenses are interesting for optical and photonic applications such as volumetric displays,optical resonators,integration of photonic components onto chips,high-resolution spectroscopy,lithography...Microbubbles acting as lenses are interesting for optical and photonic applications such as volumetric displays,optical resonators,integration of photonic components onto chips,high-resolution spectroscopy,lithography,and imaging.However,stable,rationally designed,and uniform microbubbles on substrates such as silicon chips are challenging because of the random nature of microbubble formation.We describe the fabrication of elastic microbubbles with a precise control of volume and curvature based on femtosecond laser irradiated graphene oxide.We demonstrate that the graphene microbubbles possess a near-perfect curvature that allows them to function as reflective microlenses for focusing broadband white light into an ultrahigh aspect ratio diffraction-limited photonic jet without chromatic aberration.Our results provide a pathway for integration of graphene microbubbles as lenses for nanophotonic components for miniaturized lab-on-a-chip devices along with applications in high-resolution spectroscopy and imaging.展开更多
基金This work was partially funded by the National Institutes of Health NIEHS Center Grant ES005022 and by the Rutgers University Electrical and Computer Engineering Department.
文摘We present a portable non-invasive approach for measuring indicators of inflammation and oxidative stress in the respiratory tract by quantifying a biomarker in exhaled breath condensate(EBC).We discuss the fabrication and characterization of a miniaturized electrochemical sensor for detecting nitrite content in EBC using reduced graphene oxide.The nitrite content in EBC has been demonstrated to be a promising biomarker of inflammation in the respiratory tract,particularly in asthma.We utilized the unique properties of reduced graphene oxide(rGO);specifically,the material is resilient to corrosion while exhibiting rapid electron transfer with electrolytes,thus allowing for highly sensitive electrochemical detection with minimal fouling.Our rGO sensor was housed in an electrochemical cell fabricated from polydimethyl siloxane(PDMS),which was necessary to analyze small EBC sample volumes.The sensor is capable of detecting nitrite at a low over-potential of 0.7 V with respect to an Ag/AgCl reference electrode.We characterized the performance of the sensors using standard nitrite/buffer solutions,nitrite spiked into EBC,and clinical EBC samples.The sensor demonstrated a sensitivity of 0.21μAμM^(−1) cm^(−2) in the range of 20–100μM and of 0.1μAμM^(−1) cm^(−2) in the range of 100–1000μM nitrite concentration and exhibited a low detection limit of 830 nM in the EBC matrix.To benchmark our platform,we tested our sensors using seven pre-characterized clinical EBC samples with concentrations ranging between 0.14 and 6.5μM.This enzyme-free and label-free method of detecting biomarkers in EBC can pave the way for the development of portable breath analyzers for diagnosing and managing changes in respiratory inflammation and disease.
基金the Australian Research Council for its support(Nos.DP150102972,DP190103186,and IC180100005)the National Research Foundation of Singapore for its support(No.NRF-RP15-2015-04)the financial support from the Australian Research Council(No.FL180100029)
文摘Microbubbles acting as lenses are interesting for optical and photonic applications such as volumetric displays,optical resonators,integration of photonic components onto chips,high-resolution spectroscopy,lithography,and imaging.However,stable,rationally designed,and uniform microbubbles on substrates such as silicon chips are challenging because of the random nature of microbubble formation.We describe the fabrication of elastic microbubbles with a precise control of volume and curvature based on femtosecond laser irradiated graphene oxide.We demonstrate that the graphene microbubbles possess a near-perfect curvature that allows them to function as reflective microlenses for focusing broadband white light into an ultrahigh aspect ratio diffraction-limited photonic jet without chromatic aberration.Our results provide a pathway for integration of graphene microbubbles as lenses for nanophotonic components for miniaturized lab-on-a-chip devices along with applications in high-resolution spectroscopy and imaging.