Modifying polymer properties with penetrants in the fabrication of bioresorbable scaffolds

Abstract

Methods of fabricating a bioresorbable polymer scaffold are disclosed including a step of inducing crystallization in a bioresorbable polymer construct through exposure to a liquid penetrant.

1 . (canceled) 
     
     
         2 . A method of fabricating a bioresorbable stent scaffold comprising:
 providing a tube made of a bioresorbable polymer;   exposing the tube to a solvent for a period of time, wherein the solvent is absorbed into the bioresorbable polymer which increases a crystallinity of the bioresorbable polymer; and   fabricating a scaffold having a pattern of interconnected struts from the exposed tube, wherein the solvent is methyl alcohol.   
     
     
         3 . The method of  claim 2 , wherein the bioresorbable polymer is selected from the group consisting of poly(L-lactide) (PLLA) and poly(L-lactide-co-glycolide). 
     
     
         4 . The method of  claim 2 , wherein the provided tube has a crystallinity of less than 5% and the crystallinity is increased to at least 40%. 
     
     
         5 . The method of  claim 2 , wherein the period of time of exposing the tube to the solvent is comprised from 1 to 4 days. 
     
     
         6 . The method of  claim 2 , wherein the solvent does not dissolve the bioresorbable polymer. 
     
     
         7 . The method of  claim 1 , further comprising removing the absorbed solvent prior to fabricating the scaffold. 
     
     
         8 . The method of  claim 2 , wherein a modulus of the bioresorbable polymer decreases by at least 30% in 1 to 8 days of exposure. 
     
     
         9 . The method of  claim 2 , wherein an elongation at break of the bioresorbable polymer increases by at least 100% in 1 to 8 days of exposure. 
     
     
         10 . The method of  claim 2 , wherein the exposed tube is not radially expanded prior to fabricating the scaffold. 
     
     
         11 . The method of  claim 2 , wherein the exposed tube is radially expanded prior to fabricating the scaffold. 
     
     
         12 . The method of  claim 2 , wherein the bioresorbable polymer is poly(L-lactide). 
     
     
         13 . The method of  claim 2 , further comprising:
 radially expanding the exposed tube comprising the absorbed solvent from a first diameter to a second diameter.   
     
     
         14 . The method of  claim 13 , wherein the temperature of the exposed tube is between 20 and 30 deg C. during the radial expansion. 
     
     
         15 . The method of  claim 2 , further comprising:
 crimping the scaffold comprising absorbed solvent from a first diameter to a reduced diameter over a delivery balloon.   
     
     
         16 . The method of any of the  claim 2 , wherein the absorbed solvent is at least 5 wt % of the scaffold or tube.