Lecture+15

Lecture+15 - 3/6/12 Figure 8.1 Examples of porous...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 3/6/12 Figure 8.1 Examples of porous structures. Upper left, a regular array of cylindrical pores; upper right, a foam structure; lower left, a granular structure; and lower right, a fiber matrix. In all examples, the white regions represent void spaces or the fluid phases of the media, and the black regions represent the solid phases. alginate collagen Poly(lactide-co-glycolide) fibrin 1 3/6/12 Figure 8.2 Compartments in biological tissues. (a) An electron micrograph of smooth muscle tissues, where Fib indicates fibroblast, N indicates the nucleus of smooth muscle cells, and C indicates collagen fibrils. Blood vessels are not shown in this figure (modified from Plate 35 in Ref. [1], with permission). (b) A schematic of biological tissues. The vessels can be either blood or lymph vessels. The cells include all populations in the tissue. Figure 8.3 A porous medium with cylindrical pores. 2 3/6/12 Figure 8.4 A porous medium with distributed solid spheres. 3 3/6/12 4 3/6/12 CLOT BUSTING DRUGS! ACTIVATORS antibodies streptokinase-PLG plasmin plasminogen t-PA urokinase α2antiplasmin Plasminogen Activator Inhibitor-1 (PAI-1) fibrin degradation products (FDPs) FIBRIN PLUG t-PA digesting plasma clot (Δt = 5 min between frames) Collet et al., Arterioscler Thromb Vasc Biol (2000) CLOT BUSTING DRUGS! PRESENT THERAPY DRUG BETTER THERAPY? .. .... . . . .. . .. . . .. . .. .. . . . .. . . .. .. THROMBUS TIME . . . .. . . . .. . . . . .. . . . .. . .. . . . . .. . . . . .. .. . . .. ... .. . . . . . . . . . .. . . . . . .. . .. . . . . .. . . . . . . . . . . ..... .. . . . THROMBUS ... . . . . . .. . . . .. . . . .. . . . . . . . ... . . . .. . . .. . . .. . . . . .. Important questions: 1) Biomaterial selection? 2) Release rate? 5 3/6/12 MATERIAL SELECTION! Polyethylene glycol •  Rapidly dissolves in aqueous environment •  Limits protein adsorption •  Pegylated materials (i.e. carriers, proteins) demonstrate increased circulation times Streptokinase •  Well-characterized protein •  Indirect plasminogen activator •  Serious potential complications (bleeding, immune response) MICROSPHERE PREPARATION! Vortex PEG in CHCl3 Protein solution Cumulative Protein Released (%) 100 80 60 40 20 0 0 20 40 60 80 100 120 Time (min) Vortex PVA solution Emulsion #1 Freeze and Lyophilize Emulsion #2 MESK Protein in microspheres 1 µm 10,000X 6 3/6/12 IN VITRO MODEL OF OCCLUSION! Pipette used as a flowmeter to be filled with study formulation Change height or add air to vary pressure differences Tubing filled with study formulation [2500 IU SK] Clot v= Q ȹ k ȹ ΔP = ȹ ȹ A ȹ µ ȹ L ȹ Ⱥ Darcy’s Law 3-cm Collection dish 7 3/6/12 CLOT BUSTING DRUGS! FREE SK MESK t<0 t = 5 min t<0 t = 5 min Leach et al., J Thromb Haemost 2004;2:1548-55 8 3/6/12 Whole blood clot Plasma clot Leach et al., J Thromb Haemost 2004;2:1548-55 9 3/6/12 10 3/6/12 11 3/6/12 Comparison of Predicted and Experimental Clot Lysis with MESK 100 Percentage Clot Lysis (%) Experimental Theoretical 80 60 40 20 0 0 5 10 15 20 25 Time (min) 12 3/6/12 Topics for Exam 2 Chapter 6 – Many defini:ons (mass/mole frac:on, average velocity, flux, etc.) Fick’s 1st law Es:ma:on of Dij for proteins/DNA/RNA (Stokes, Wilkie ­Chang, etc.) Fick’s 2nd law  ­ ­ Conserva:on rela:ons of mass transfer Various coordinate systems, find conc. profile, flux, release rate Unsteady state diffusion in 1 ­D Find flux given concentra:on gradients, calculate C(x) with charts Chapter 7 – Diffusion with convec:on (conserva:on rela:ons) Mass transfer coefficients – k0(Re, Sc) Dimensionless numbers (Re, Sc, Pe, Sh, etc.) Hemodialyzers Chapter 8 – Flow through porous media (general concepts) Porosity, tortuosity, Knudsen diffusion, etc. 13 ...
View Full Document

Ask a homework question - tutors are online