A dry method for surface modification of SU-8 for immobilization of biomolecules using a hotwire induced pyrolytic process
Prof. Soumyo Mukherji and his team at Department of Biosciences and Bioengineering have developed a rapid and simple process for activation of epoxy surfaces such as SU-8 (Glycidyl ether of bisphenol A), to enable surface immobilization of molecules with carboxyl and / or amino functional groups.
Microsystems for biological applications require immobilization of biological molecules within the device. Conventionally, substrate materials used for these devices have been silicon and noble metals (e.g. gold) which have been found to have shortcomings in terms of their high Young's modulus, biocompatibility and their suitability for micro fabrication. Immobilization of bio-molecules onto epoxy surfaces such as SU-8 is of interest because of their application in surface modification, bioMEMS, biomolecule immobilization related assays, biosensors, membrane bioreactors, clinical diagnostics, molecular biology, agriculture, environmental science and chemical / biochemical industry.
Bare SU-8 patterned with conventional photolithography techniques does not allow the immobilization of antibodies on its surface. Several methods are known for the modifications of polymer surfaces are not suitable for SU8 surface modification. The process of the invention developed at IIT Bombay involves grafting of NH2+ groups on the epoxy (e.g. SU-8) surface using hotwire induced pyrolytic decomposition of ammonia under vacuum, followed by antibody immobilization on the treated SU-8 surface. The process of the invention enables single or multi-step tailored immobilization of biomolecules (antigen, antibodies, proteins, DNA, RNA enzymes etc.) on the modified epoxy surface.