Biointerfaces Institute Mcmaster University
This study has been motivated by a major obstacle in the use of glassy and ceramic materials as injectable biocompatible carriers: Despite the fact that the vast majority of oxide-based biomaterials studies have been carried out on silica, no major pharmaceutical company has 'raised the glove' to get the FDA and the other regulatory agencies approval for this material as an injectable carrier of therapeutical components. Together with Prof. David Avnir (The Hebrew University of Jerusalem) we have identified a potential solution to this hurdle, namely to shift the focus from silicas to aluminas. This recommended shift is based on the fact that alumina is the most widely injectable adjuvant in practically all major-volume vaccinations, and is FDA-approved for that purpose.
We regard this current status as half-way towards eventual approval of alumina as a general carrier of drugs and bioactive molecules. Towards that goal we carried out a series of in-vitro and in-vivo studies to prove the feasibility of the concept. This involved the development of an original approach biocompatible method for synthesizing highly pure alumina, which is identical to the currently used alumina in vaccines. Entrapment of series of albumins revealed a thermal stability shift to higher temperatures, amounting to more than 51°C compared to solution. This observation was subsequently extended to therapeutical enzymes: asparaginase, horseradish peroxidase, acid phosphatase. The results indicated that the enzymes not only retain their structure at elevated temperatures, but also demonstrate remarkable stability with no practical change in activity under prolonged heating up to 60°?. Based on new conception of injectable sol – gel alumina, we developed an efficient wound healing materials with strong scar-size decreasing effect; new class of thrombolytic systems by entrapment of tissue plasminogen activator within alumina; and many others biomaterials which appear practically every day.