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P. Itotia, M. C. Butler, J. M. Sullivan; An Instrument for High Throughput Screening of Candidate Agents for Photodynamic Therapy. Invest. Ophthalmol. Vis. Sci. 2007;48(13):4584.
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To develop an instrument for high throughput screening (HTS) of potential photodynamic therapy agents. Pathological angiogenesis in the retina or choroid underlies visual loss in diabetic retinopathy of age-related macular degeneration. Photodynamic therapy with small ligands is one means to promote closure and involution of the neovascular tubes in pathological angiogenesis. Novel types of antiangiogenic agents involving nanoscience technology or engineered genes offer a new landscape for therapy. Better tools are needed to evaluate such agents rapidly.
An electro-optic device was designed and constructed around 96-well arrays of high intensity LEDS with distinct spectral emission bands. Several such LED arrays were made with peak wavelengths at 465 (blue), 520 (green), and 630 (red) nm. Additional arrays at 570 (yellow) and 590 (orange) nm are being constructed. Selected LEDs had narrow spatial emission bands (FWHM 30 degrees) such that when 96-well arrays of cultured cells were stacked onto the LED arrays, the beam diameter fills the cellular growth well aperture. LED intensity was tightly regulated over several log fold range by rheostat-based DC current control that allows repeatable settings. The device is cooled by forced air flow across the LED arrays and can be used on the lab benchtop or in the cell culture incubator.
At each respective wavelength, arrays demonstrated uniformity of intensity across both the LED and cellular growth surfaces over wide ranges of intensity. Smooth transitions in intensity between repeatable settings allow reliable input photonic titration curves. Minimum and maximum mean intensities at the different wavelengths immediately above the array were determined (465 nm: 0.18 - 20.5 mW/cm2; 520 nm: 0.14 - 19.7 mW/cm2; 630 nm: 0.17 - 18.7 mW/cm2). The device is being used to examine cellular toxicity by small light sensitive molecules and expressed proteins that generate free radicals upon photon absorption.
An LED array device was constructed for testing the ability of agents to promote photochemical toxicity of mammalian cells. A range of wavelengths and intensities was achieved to explore a diverse photochemical landscape for cellular toxicity potential.
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