Browsing by Author "Sherlock, Tim"
Now showing 1 - 3 of 3
- Results Per Page
- Sort Options
Item Depth-resolved imaging and detection of microretroreflectors within biological tissue using Optical Coherence Tomography(Biomedical Optics Express, 2010) Ivers, Steven N.; Baranov, Stephan A.; Sherlock, Tim; Kourentzi, Katerina D.; Ruchhoeft, Paul; Willson, Richard C.; Larin, Kirill V.A new approach to in vivo biosensor design is introduced, based on the use of an implantable micron-sized retroreflector-based platform and non-invasive imaging of its surface reflectivity by Optical Coherence Tomography (OCT). The possibility of using OCT for the depth-resolved imaging and detection of micro-retroreflectors in highly turbid media, including tissue, is demonstrated. The maximum imaging depth for the detection of the micro-retroreflector-based platform within the surrounding media was found to be 0.91 mm for porcine tissue and 1.65 mm for whole milk. With further development, it may be possible to utilize OCT and micro-retroreflectors as a tool for continuous monitoring of analytes in the subcutaneous tissue.Item Detection and Monitoring of Microparticles Under Skin by Optical Coherence Tomography as an Approach to Continuous Glucose Sensing Using Implanted Retroreflectors(IEEE Sensors Journal, 2015-09) Wang, Shang; Sherlock, Tim; Salazar, Betsy; Sudheendran, Narandran; Manapuram, Ravi K.; Kourentzi, Katerina D.; Ruchhoeft, Paul; Willson, Richard C.; Larin, Kirill V.We demonstrate the feasibility of using optical coherence tomography (OCT) to image and detect 2.8 ?m diameter microparticles (stationary and moving) on a highly-reflective gold surface both in clear media and under skin in vitro. The OCT intensity signal can clearly report the microparticle count, and the OCT response to the number of microparticles shows a good linearity. The detect ability of the intensity change (2.9%�5%) caused by an individual microparticle shows the high sensitivity of monitoring multiple particles using OCT. An optical sensing method based on this feasibility study is described for continuously measuring blood sugar levels in the subcutaneous tissue, and a molecular recognition unit is designed using competitive binding to modulate the number of bound microparticles as a function of glucose concentration. With further development, an ultra-small, implantable sensor might provide high specificity and sensitivity for long-term continuous monitoring of blood glucose concentration.Item Helium beam shadowing for high spatial resolution patterning of antibodies on microstructured diagnostic surfaces(Biointerphases, 2013) Cacao. Eliedonna; Sherlock, Tim; Nasrullah, Azeem; Kempter, Steven; Knoop, Jenniffer; Kourentzi, Katerina D.; Ruchhoeft, Paul; Stein, Gila E.; Atmar, Robert L.; Willson, Richard C.We have developed a technique for the high-resolution, self-aligning, and high-throughput patterning of antibody binding functionality on surfaces by selectively changing the reactivity of protein-coated surfaces in specific regions of a workpiece with a beam of energetic helium particles. The exposed areas are passivated with bovine serum albumin (BSA) and no longer bind the antigen. We demonstrate that patterns can be formed (1) by using a stencil mask with etched openings that forms a patterned exposure, or (2) by using angled exposure to cast shadows of existing raised microstructures on the surface to form self-aligned patterns. We demonstrate the efficacy of this process through the patterning of anti-lysozyme, anti-Norwalk virus, and anti-Escherichia coli antibodies and the subsequent detection of each of their targets by the enzyme-mediated formation of colored or silver deposits, and also by binding of gold nanoparticles. The process allows for the patterning of three-dimensional structures by inclining the sample relative to the beam so that the shadowed regions remain unaltered. We demonstrate that the resolution of the patterning process is of the order of hundreds of nanometers, and that the approach is well-suited for high throughput patterning.