New Advances In Membranes For Antibiotic Recovery and Controlled Release

This presentation covers new advances in two types of membranes: (1) supported liquid membranes (SLMs) with strip dispersion for recovery of antibiotics and (2) nanoporous polycaprolactone membranes for controlled release.  SLMs with their stability ensured using strip dispersion have been studied for antibiotic recovery.  Cephalexin has been extracted and concentrated with high recovery.  A mass transfer analysis has shown that the resistance from the extraction reaction is dominant.  Initial results from a 4-component feed mixture derived from its enzymatic synthesis have shown selective Cephalexin recovery possible.  This allows Cephalexin recovery from the mixture in conjunction with complexation without enzyme deactivation , which commonly occurs when complexation is conducted in enzymatic reaction mixtures. On nanoporous polycaprolactone (PCL) membranes for controlled release , a constant drug release rate is of paramount importance to implantable drug delivery systems in finding the remedy against chronic diseases.  We have synthesized nanoporous PCL membranes to achieve the zero-order constant release rate via the combination of thermally- and nonsolvent-induced phase separations.  Pore connectivity was improved significantly when coagulation bath temperature was lowered from 35 to 5°C.  By using a 5°C water coagulation bath , the average pore size reduced from about 90 nm to 55 nm while increasing the casting solution concentration from 15 wt% to 25 wt% PCL.  Thus , by varying the polymer concentration of the casting solution , the drug release rate can be well controlled with the constant zero-order rate using the higher polymer concentration.