Trapping of vesicles on patterned surfaces by physisorption for potential biosensing applications

The pre-defined selective positioning of a controlled number of vesicles on a rigid substrate is crucial in many potential applications such as diagnostics, biosensors, lab-on-a chip, microanalyses and reaction chambers. In this paper, the vesicles made up of block copolymer using Poly [-(2-methyloxazoline) -poly- (dimethylsiloxane)-poly- (2-methyloxazoline)] (ABA) with dimensions of 100-200 nm are trapped by physisorption on hydrophilic surfaces. We discuss the protocols established for vesicle trapping. The optimum conditions obtained for physisorption is 15 minutes incubation followed by one cycle of DI water rinse. Trapping of 1-10 vesicles in lobe shape micro-wells fabricated by photo lithography using photoresist on UltraStick™ slides was demonstrated. To overcome the issue of amalgamation of emitted light from optically sensitive photoresist and fluorescently tagged vesicles, an alternative approach of Si/SiO₂ microwell array coupled with APTES (3-AminoPropylTriEthoxySilane) treated bottom surfaces was developed.