The creation of plasmons in metal films or structures has been shown to enhance the processes of fluorescence, phosphorescence, and chemiluminescence; now, researchers at Ben-Gurion University of the ...Negev (Beer-Sheva, Israel) and the University of Maryland Biotechnology Institute (Baltimore, MD) have demonstrated that the approach works for bioluminescence as well.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Plasmonic Glucose Sensing Aslan, Kadir; Lakowicz, Joseph R.; Geddes, Chris D.
Glucose Sensing
Book Chapter
Diabetes results in long-term health disorders including cardiovascular disease and blindness. One of the major challenges in the management of diabetes is the monitoring of glucose concentrations. ...Yet after several decades of intense research,1–5 still no method is available for the continuous non-invasive monitoring of blood glucose, never mind a generic technology which could be applied across-the-board for glucose sensing in other physiological fluids. In fact the invasive nature of glucose monitoring in blood, primarily undertaken by “finger pricking”, has further fueled the search for non-invasive technologies,6–12 which can potentially monitor physiological glucose in fluids such as urine and tears based on the boronic acid / glucose6–11 and glucose-binding protein / glucose12 interactions.
Diabetes can lead to severe health complications over time, such as neuropathies, blindness, cancer, etc., 1,2 and it is one of the most concerned pathologies that cause patients death. The most ...effective way to manage diabetes is only possible by continuous, or at least, frequent blood glucose estimation, and subsequent drug and food administration. Consequently, the importance of diabetic control has resulted in worldwide efforts to develop non-or minimally-invasive methods for body glucose estimation 3–13. Among these, the glucose monitoring using near infrared spectroscopy 3,4, optical rotation 5,6, colorimetric 7,8, and fluorescence detection 9–13 are notable. However, an enzyme based “finger-pricking” method is still the most commonly used technology in diabetic assessment. This method is relatively painful process and it does suffer from a few practical problems. The first one is inconvenience and the required compliance by patients, which is often difficult for both the young and old patients; while the second is that this is not a continuous monitoring method. Despite intensive efforts, no compatible device for the non-invasive and continuous monitoring of glucose estimation is available.
Fluorescence experiments are typically performed in sample geometries that are large relative to the size of the fluorophores and relative to the absorption and emission wavelengths. In this ...arrangement the fluorophores radiate into free space. Most of our knowledge and intuition about fluorescence is derived from the spectral properties observed in these free-space conditions. However, the presence of nearby metallic surfaces or particles can alter the free-space condition, which can result in dramatic spectral changes which are distinct from those observable in the absence of metal surfaces. Remarkably, metal surfaces can increase or decrease the radiative decay rates of fluorophores and increase the extent of resonance energy transfer (RET) (Figure 1).These effects are due to interactions of the excited-state fluorophores with free electrons in the metal, the so-called surface plasmon electrons, which polarize the metal and produce favorable effects on the fluorophore. The effects of metallic surfaces are complex and include quenching at short distances, spatial variation of the incident light field, and changes in the radiative decay rates (Figure 2). We refer to the use of fluorophore-metal interactions as radiative decay engineering (RDE) or metal enhanced fluorescence (MEF).
The biotechnology and medical diagnostics industries could soon benefit from a technique that promises enhanced sensitivity over conventional fluorescence detection methods. Developed at the ...University of Maryland in Baltimore and called directional surface-plasmon-coupled emission, it shows promise for applications such as DNA hybridization, high-throughput screening for drug discovery, singlemolecule detection, immunoassay and bioassay development, protein analysis and emerging nanophotonics technologies. Surface plasmons are basically electron oscillations on the surface of metals - or, more specifically, in an interfacial region between a metal and a dielectric medium. Although usually nonradiative, they are the basis of surface plasmon resonance. This process, which is used to measure bioaffinity reactions, occurs when irradiation with photons excites the surface plasmons on the metal to radiate in a measurable way. Excitation of surface plasmons also can occur on subwavelength-thick silver, gold or aluminum films. And in some cases, placing an excited fluorophore next to the thin film will excite the plasmons to' radiate into the substrate.
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