Modular Aptamer Switches for the Continuous Optical Detection of Small-Molecule Analytes in Complex Media.
Advanced materials (Deerfield Beach, Fla.)
Aptamers are a promising class of affinity reagents because signal transduction mechanisms can be built into the reagent, so that they can directly produce a physically measurable output signal upon target binding. However, endowing the signal transduction functionality into an aptamer remains a trial-and-error process that can compromise its affinity or specificity and typically requires knowledge of the ligand binding domain or its structure. In this work, we describe a design architecture that can convert an existing aptamer into a "reversible aptamer-switch" whose kinetic and thermodynamic properties can be tuned without a priori knowledge of the ligand binding domain or its structure. Finally, by combining these aptamer-switches with evanescent-field based optical detection hardware that rejects sample autofluorescence, we demonstrate the first optical biosensor system that can continuously measure multiple biomarkers (dopamine and cortisol) in complex samples (artificial cerebrospinal fluid and undiluted plasma) with second-scale time resolution at physiologically relevant concentration ranges. This article is protected by copyright. All rights reserved.
View details for DOI 10.1002/adma.202304410
View details for PubMedID 37975267
An antibody-based molecular switch for continuous small-molecule biosensing.
2023; 9 (38): eadh4978
We present a generalizable approach for designing biosensors that can continuously detect small-molecule biomarkers in real time and without sample preparation. This is achieved by converting existing antibodies into target-responsive "antibody-switches" that enable continuous optical biosensing. To engineer these switches, antibodies are linked to a molecular competitor through a DNA scaffold, such that competitive target binding induces scaffold switching and fluorescent signaling of changing target concentrations. As a demonstration, we designed antibody-switches that achieve rapid, sample preparation-free sensing of digoxigenin and cortisol in undiluted plasma. We showed that, by substituting the molecular competitor, we can further modulate the sensitivity of our cortisol switch to achieve detection at concentrations spanning 3.3 nanomolar to 3.3 millimolar. Last, we integrated this switch with a fiber optic sensor to achieve continuous sensing of cortisol in a buffer and blood with <5-min time resolution. We believe that this modular sensor design can enable continuous biosensor development for many biomarkers.
View details for DOI 10.1126/sciadv.adh4978
View details for PubMedID 37738337
Y-Z cut lithium niobate longitudinal piezoelectric resonant photoelastic modulator
2022; 30 (26): 47103-47114
The capability to modulate the intensity of an optical beam has scientific and practical significance. In this work, we demonstrate Y-Z cut lithium niobate acousto-optic modulators with record-high modulation efficiency, requiring only 1.5 W/cm2 for 100% modulation at 7 MHz. These modulators use a simple fabrication process; coating the top and bottom surfaces of a thin lithium niobate wafer with transparent electrodes. The fundamental shear acoustic mode of the wafer is excited through the transparent electrodes by applying voltage with frequency corresponding to the resonant frequency of this mode, confining an acoustic standing wave to the electrode region. Polarization of light propagating through this region is modulated at the applied frequency. Polarization modulation is converted to intensity modulation by placing the modulator between polarizers. To showcase an important application space for this modulator, we integrate it with a standard image sensor and demonstrate 4 megapixel time-of-flight imaging.
View details for DOI 10.1364/OE.476970
View details for Web of Science ID 000914755600002
View details for PubMedID 36558647
- Self-Powered High Energy Laser Detectors via Thermoelectric Generators SPIE-INT SOC OPTICAL ENGINEERING. 2021
Photothermal actuation of levitated pyrolytic graphite revised
View details for DOI 10.1063/5.0061390
- High-energy laser detection through thermoelectric generators OPTICAL ENGINEERING 2020; 59 (11)
Autonomous Microrobotic Manipulation Using Visual Servo Control
2020; 11 (2)
This describes the application of a visual servo control method to the microrobotic manipulation of polymer beads on a two-dimensional fluid interface. A microrobot, actuated through magnetic fields, is utilized to manipulate a non-magnetic polymer bead into a desired position. The controller utilizes multiple modes of robot actuation to address the different stages of the task. A filtering strategy employed in separation mode allows the robot to spiral from the manipuland in a fashion that promotes the manipulation positioning objective. Experiments demonstrate that our multiphase controller can be used to direct a microrobot to position a manipuland to within an average positional error of approximately 8 pixels (64 µm) over numerous trials.
View details for DOI 10.3390/mi11020132
View details for Web of Science ID 000520181500021
View details for PubMedID 31991607
View details for PubMedCentralID PMC7074596
- Optical control and manipulation of diamagnetically levitated pyrolytic graphite AIP ADVANCES 2019; 9 (12)
- Optomechanical Actuation of Diamagnetically Levitated Pyrolytic Graphite IEEE TRANSACTIONS ON MAGNETICS 2019; 55 (7)
A Miniature Reconfigurable Circularly Polarized Antenna Using Liquid Microswitches
View details for Web of Science ID 000380567600022
Microstrip Antenna Tuning using Variable Reactive Microelectromechanical Systems
IEEE. 2011: 1828-1833
View details for Web of Science ID 000302341400281