Researchers at University of Munster Target Molecular Imaging (Optimizing the bioavailability of small molecular optical imaging probes by conjugation to an albumin affinity tag)
By a News Reporter-Staff News Editor at Biotech Week -- Current study results on Molecular Imaging have been published. According to news reporting out of Munster, Germany, by NewsRx editors, research stated, "Small molecular imaging probes are often found to be rapidly cleared from the circulation. In order to improve signal to noise ratio (SNR) by high probe accumulation in the target tissue we intended to prolong the presence of the probes in the circulation by exploiting inherent transport mechanisms."
Our news journalists obtained a quote from the research from the University of Munster, "Human serum albumin (HSA) is playing an increasingly important role as a drug carrier in clinical settings and drugs directly bound to albumin or attached to albumin binding moieties have been successfully developed for treatment approaches. To optimize the bioavailability of existing fluorescent probes, a hydrophobic affinity tag is installed, which enhances albumin binding. In a first experiment an endothelin-A receptor (ETAR) probe is modified by inserting a trivalent linker, attaching an albumin affinity tag and labeling the conjugate with the fluorescent dye Cy 5.5. The spectroscopic properties of the conjugate are examined by photometer-and fluorometer measurements in comparison to a probe without albumin binding tag. Albumin binding was proven by agarose gel electrophoresis. The affinity towards ETAR was confirmed in vitro by cell binding assays on human fibrosarcoma cells (HT-1080) and in vivo by murine xenograft imaging studies. In vitro, the modified probe retains high target binding in the absence and presence of albumin. Binding could be blocked by predosing with ETAR antagonist atrasentan, proving specificity. The in vivo examinations in comparison to the established probe showed a reduced renal elimination and a prolonged circulation of the tracer resulting in significantly higher signal intensity (SI) at the target and a higher signal-to-noise ratio (SNR) between 3 h and 96 h after injection. In summary, we designed a small molecular, non-peptidic fluorescent probe which targets ETAR and reversibly binds to serum albumins. The reversible binding to albumin enhances the biological half-life of the probe substantially and enables near infrared optical imaging of subcutaneous tumors for several days."
According to the news editors, the research concluded: "This approach of reversibly attaching probes to serum albumin may serve as a tool to optimize tracer distribution for more precise target characterization in molecular imaging experiments."
For more information on this research see: Optimizing the bioavailability of small molecular optical imaging probes by conjugation to an albumin affinity tag. Journal of Controlled Release, 2014;186():32-40. Journal of Controlled Release can be contacted at: Elsevier Science Bv, PO Box 211, 1000 Ae Amsterdam, Netherlands. (Elsevier - www.elsevier.com; Journal of Controlled Release - www.elsevier.com/wps/product/cws_home/502690)
Our news journalists report that additional information may be obtained by contacting A. Hahnenkamp, University of Munster, Interdisciplinary Center Clin Res IZKF, D-48149 Munster, Germany. Additional authors for this research include W. Alsibai, C. Bremer and C. Holtke (see also Molecular Imaging).
Keywords for this news article include: Europe, Munster, Germany, Nanotechnology, Molecular Imaging, Emerging Technologies
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