An aptamer based microfluidic chip for impedimetric detection of Ranibizumab in a bioreactor

Abstract

We have developed an aptamer based microfluidic chip for inline monitoring of Ranibizumab in bioreactors. Aptamers for Ranibizumab were generated using 10 rounds of the SELEX process. Two of the aptamers exhibited high affinity towards the target analyte with a dissociation constant within 20–30 nM range. The one with best affinity towards analyte was immobilized on gold micro-electrodes on a microfluidic chip, which was fabricated with glass base and PDMS top using conventional photolithographic technique. Immobilization steps were characterized using FTIR and EIS. Non-faradaic EIS measurement was used for label-free detection of Ranibizumab. The linear range of detection and LOD were found to be 25−100 nM and 25 nM respectively, which was significantly better than HPLC based detection method (about 240 nM). Further, this microchip-based detection did not require sample preconcentration or preprocessing and as a result, the detection time was reduced to 30 min compared to several hours with HPLC. The proposed detection system was validated using real samples of culture broths and no interferences were observed. Statistical analysis confirmed the correlation between the microfluidic chip and HPLC based method. As the selected aptamer was found highly specific for Ranibizumab, it can also be used for purification of Ranibizumab in affinity columns. Therefore, commercialization of this aptamer and microfluidic chip could have a significant impact on purification, various steps during biopharmaceutical production (clone selection and process optimization) and inline detection of Ranibizumab.