Polymer Pen Lithography For Biosensing And Biomedical Applications

Polymer pen lithography (PPL) is a powerful method to generate patterns of bioactive substances with features in the nano-to microrange and over large surface areas (square centimeters). Especially, it allows for the generation of multiplexed pattern arrays (i.e. more than one component within near vicinity or within one sub-pattern). This makes the technology very interest for applications in the biomedical field ranging from sensing, to screening purposes and cell culture experiments. The multiplexing capability allows to present more than one component within an underlying pattern to a single cell, offering many options for polarization, differentiation and activation experiments. This paper will present recent progress in the application of multiplexed PPL in regard to covalent immobilization by click-chemistry approaches and introduction of versatile binding motifs in form of oligo-nucleotides for DNA-directed immobilization (DDI). The generated patterns can be encapsulated within microfluidic chips for easier handling and enhanced stability and reproducibility in use. Two examples of biomedical applications are presented in the form of mast cell activation studies and the capture of circulating tumor cells (CTCs) in such systems. As example for applications in biosensing, the use of PPL generated ink pads for the multiplexed functionalization of arrays of goblet shaped whispering gallery mode (WGM) sensors is demonstrated.