Bivalent engagement of endothelial surface antigens is critical to prolonged surface targeting and protein delivery in vivo

Targeted drug delivery to the endothelium has the potential to generate localized therapeutic effects at the blood- tissue interface. For some therapeutic cargoes, it is essential to maintain contact with the bloodstream to exert protective effects. The pharmacokinetics (PK) of endothelial surface- targeted affinity ligands and biotherapeutic cargo remain a largely unexplored area, despite obvious translational implications for this strategy. To bridge this gap, we site- specifically radiolabeled mono- (scFv) and bivalent (mAb) affinity ligands specific for the endothelial cell adhesion molecules, PECAM- 1 (CD31) and ICAM- 1 (CD54). Radiotracing revealed similar lung biodistribution at 30 minutes post- injection (79.3% ± 4.2% vs 80.4% ± 10.6% ID/g for αICAM and 58.9% ± 3.6% ID/g vs. 47.7% ± 5.8% ID/g for αPECAM mAb vs. scFv), but marked differences in organ residence time, with antibodies demonstrating an order of magnitude greater area under the lung concentration vs. time curve (AUCinf 1698 ± 352 vs. 53.3 ± 7.9 ID/g*hrs for αICAM and 1023 ± 507 vs. 114 ± 37 ID/g*hrs for αPECAM mAb vs scFv). A physiologically based pharmacokinetic model, fit to and validated using these data, indicated contributions from both superior binding characteristics and prolonged circulation time supporting multiple binding- detachment cycles. We tested the ability of each affinity ligand to deliver a prototypical surface cargo, thrombomodulin (TM), using one- to- one protein conjugates. Bivalent mAb- TM was superior to monovalent scFv- TM in both pulmonary targeting and lung residence time (AUCinf 141 ± 3.2 vs 12.4 ± 4.2 ID/g*hrs for ICAM and 188 ± 90 vs 34.7 ± 19.9 ID/g*hrs for PECAM), despite having similar blood PK, indicating that binding strength is more important parameter than the kinetics of binding. To maximize bivalent target engagement, we synthesized an oriented, end- to- end anti- ICAM mAb- TM conjugate and found that this therapeutic had the best lung residence time (AUCinf 253 ± 18 ID/g*hrs) of all TM modalities. These observations have implications not only for the delivery of TM, but also potentially all therapeutics targeted to the endothelial surface.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156501/3/fsb220760_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156501/2/fsb220760-sup-0001-Supinfo.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156501/1/fsb220760.pd

Effects of Irradiation on Porous Silicon

Besides the well-known effect of photoluminescence, the impinging of photons and other kinds of particles such as electrons, ions, and muons on porous silicon produces important effects. Some of these effects can modify the structure and properties of the material, distorting the interpretation of data based on the use of irradiation. Some of the irradiation effects are useful in different applications such as photodynamic therapy or display applications. This work is a review of the effects of irradiation on porous silicon.Fil: Koropecki, Roberto Roman. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Física del Litoral. Universidad Nacional del Litoral. Instituto de Física del Litoral; ArgentinaFil: Arce, Roberto Delio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Física del Litoral. Universidad Nacional del Litoral. Instituto de Física del Litoral; Argentin