"Sustained Release of Bevacizumab from BioSilicon" (leaked)
The purpose of this work was to exploit the tunable
properties of BioSilicon (a form of oxidized porous silicon) as a
substrate to provide long term release Bevacizumab (Avastin).
BioSilicon can be manufactured with varying pore size and high
surface area. Proteins including antibodies, adsorb by a combination
of electrostatic, Van der Waals, and hydrophobic forces, while
changes in surface hydration, entropy, and protein structure (shape
and size) are also important. Strong electrostatic forces on the surface
not only enable the antibody to adsorb but also subsequently desorb
from the surface. In this work we evaluated the effect of pore size on
Avastin release over a period of three weeks
Oxidised porous silicon (OPS) was prepared with pore
sizes ranging from of 10 to 100nm (the hydrodynamic radii of
Avastin monomer estimated to be ~ 14.52nm). 5mg of OPS was
added to 25μL of a 25mg/mL Avastin stock solution (prepared from
the commercial formulation) and allowed to equilibrate overnight
at room temperature (22.5οC). 1975μL of Phosphate buffer saline
(PBS: pH7.4; 37οC) was added to the equilibrated OPS particles.
The suspension was then hand mixed for 10 seconds and centrifuged.
1mL of PBS was taken to calculate post loading concentration and
1mL of PBS was freshly added to the dissolution pot. Sampling
was performed every 24hrs for 20 days. Samples were analysed by
Size-Exclusion Chromatography coupled with UV and fluorescence
Maximal adsorption was obtained with OPS of average pore
size 25 to 30nm which provided approximately 12% (w/w) loading,
larger pores gave slightly less loading (10% at 50nm and 8% at
100nm) due to lower surface area. Material with a pore size of 10nm.
Maryland, just curious why you post this on the ALIM MB? Biosilicon has very little to do with ALIM, it's a pSivida owned technology. It's good. It will be a game changer in the eye space and in other applications that need biologic sustained delivery.