Fast Temporal Response Fiber-Optic Chemical Sensors Based on the Photodeposition of Micrometer-Scale Polymer Arrays

Abstract

Fiber-optic chemical sensor microarrays for the detection of pH and O2 have been developed with subsecond response times. Sensor microarrays are fabricated by the covalent immobilization (pH sensor arrays) or the physical entrapment (O2 sensor arrays) of fluorescent indicators in photodeposited polymer matrices on optical imaging fibers. Polymer microarrays are comprised of thousands of individual elements photodeposited as hemispheres such that each element of the sensor array is coupled directly to a discrete optical element of the imaging fiber and is not in contact with other neighboring elements. Because of the hemispherical shape and the individuality of the array elements, diffusion of analyte to the sensor elements is dominated by radial diffusion, resulting in a rapid response time. pH-sensitive arrays based on fluorescein respond to a 1.5-unit pH change within 300 ms, while the O2-sensitive arrays respond to O2 changes within 200 ms (90% of steady state response).

Biosensors for real-time in vivo measurements

“…This in turns lead to significantly smaller sensing elements that can be arrayed at very high density. It has accordingly been possible to construct 3-4 m diameter array sensing elements for oxygen and pH with response times of 200-300 ms (Healey and Walt, 1997). So far there appear to be few examples of DNA or RNA sensors in vivo applications, and taking a "snapshot" by processing a sample at a defined time may be sufficient.…”

Combined Imaging and Chemical Sensing with a Disposable Microscope Objective Chemical Sensor

“…The positive drift was the expected luminescence increase from the equilibration of the 25% oxygen-purged PBS with the ambient laboratory atmospheric oxygen partial pressure (21%). The steady-state response time for a 3% oxygen step change was on the order of 0.5 s. Faster response times for larger oxygen step changes are anticipated when a thinner sensing layer is employed (68). While it was not a focus of this work, these results indicate that it would be possible for a dMOCS to acquire dissolved oxygen measurements (69,70) from cells cultured in standard 35-mm dishes (ideally within an environmental microscope chamber).…”

Protein and Chemical Microarrays—Powerful Tools for Proteomics

“…For example, we have used whole cell binding assay to screen random peptide libraries for leukemia cell binding ligands. The positive ligands are then resynthesized, immobilized on plastic or glass slides, and these peptide microarrays can be used to probe whole blood derived from patients with leukemia [65]. Our ultimate goal is to develop microarrays of cancer targeting peptides that can be probed, allowing physicians to rapidly identify the therapeutic peptide cocktail effective for a specific patient.…”