Detection of FITC-cortisol via Modulated Supraparticle Lighthouses

Petkus, Matthew M.; Mclauchlin, Melissa L.; Vuppu, Anil K.; Rios, Lynnette; Garcia, and Antonio A.; Hayes, Mark A.

doi:10.1021/ac0512204

Cited by 23 publications

(26 citation statements)

References 32 publications

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“…Current methods for cortisol testing include the saliva test [ 13 Petkus et al , 2006], the Fluorometric assay [ 14 Appel et al , 2005], Fluorescence Polarization [ 15 Cullum, et. al., 2006] and Reverse Phase Chromatography [ 16 ,Gatti et al , 2005].…”

Section: Introductionmentioning

confidence: 99%

A realtime and continuous assessment of cortisol in ISF using electrochemical impedance spectroscopy

Venugopal

Arya

Chornokur

et al. 2011

Sensors and Actuators A: Physical

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This study describes the functioning of a novel sensor to measure cortisol concentration in the interstitial fluid (ISF) of a human subject. ISF is extracted by means of vacuum pressure from micropores created on the stratum corneum layer of the skin. The pores are produced by focusing a near infrared laser on a layer of black dye material attached to the skin. The pores are viable for approximately three days after skin poration. Cortisol measurements are based on electrochemical impedance (EIS) technique. Gold microelectrode arrays functionalized with Dithiobis (succinimidyl propionate) self-assembled monolayer (SAM) have been used to fabricate an ultrasensitive, disposable, electrochemical cortisol immunosensor. The biosensor was successfully used for in-vitro measurement of cortisol in ISF. Tests in a laboratory setup show that the sensor exhibits a linear response to cortisol concentrations in the range 1 pm to 100 nM. A small pilot clinical study showed that in-vitro immunosensor readings, when compared with commercial evaluation using enzyme-linked immunoassay (ELISA) method, correlated well with cortisol levels in saliva and ISF. Further, circadian rhythm could be established between the subject's ISF and the saliva samples collected over 24 hours time-period. Cortisol levels in ISF were found reliably higher than in saliva. This Research establishes the feasibility of using impedance based biosensor architecture for a disposable, wearable cortisol detector. The projected commercial in-vivo real-time cortisol sensor device, besides being minimally invasive, will allow continuous ISF harvesting and cortisol monitoring over 24 hours even when the subject is asleep. Forthcoming, this sensor could be interfaced to a wireless health monitoring system that could transfer sensor data over existing wide-area networks such as the internet and a cellular phone network to enable real-time remote monitoring of subjects.

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Section: Introductionmentioning

confidence: 99%

A realtime and continuous assessment of cortisol in ISF using electrochemical impedance spectroscopy

Venugopal

Arya

Chornokur

et al. 2011

Sensors and Actuators A: Physical

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“…It has been used in previous work to achieve detection limits in the pM range. 30,32 However, because the reference signal generated by lock-in amplification is a sine wave, its correlation with the input wave is imperfect and signal power is lost. This has been addressed in part by the development of a new signal processing method that maintains the input signal modulation but uses a new waveform as the reference signal.…”

Section: Resultsmentioning

confidence: 99%

Sensitive detection of cardiac biomarkers using a magnetic microbead immunoassay

Woolley

Hayes

2015

Anal. Methods

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To achieve improved sensitivity in cardiac biomarker detection, a batch incubation magnetic microbead immunoassay was developed and tested on three separate human protein targets: myoglobin, heart-type fatty acid binding protein, and cardiac troponin I. A sandwich immunoassay was performed in a simple micro-centrifuge tube allowing full dispersal of the solid capture surface during incubations. Following magnetic bead capture and wash steps, samples were analyzed in the presence of a manipulated magnetic field utilizing a modified microscope slide and fluorescent inverted microscope to collect video data files. Analysis of the video data allowed for the quantitation of myoglobin, heart-type fatty acid binding protein and cardiac troponin I to levels of 360 aM, 67 fM, and 42 fM, respectively. Compared to the previous detection limit of 50 pM for myoglobin, this offers a five-fold improvement in sensitivity. This improvement in sensitivity and incorporation of additional markers, along with the small sample volumes required, suggest the potential of this platform for incorporation as a detection method in a total sample analysis device enabling multiplexed detection for the analysis of clinical samples.

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“…The fluorescence intensity of the chains in the swarm depends on the orientation of the chains, with more light emitted when the chains are oriented parallel to the image plane than when the chains are oriented perpendicular to the image plane. This angular dependence can be employed to modulate fluorescence from chains and separate it from the background autofluorescence [40,41]. The tweezers enhance the formation of chains by concentrating the particles, and allow swarms to be guided to places of interest.…”

Section: Swarm Formation and Controlmentioning

confidence: 99%