Low Cost and Lithography-free Stamp fabrication for Microcontact Printing
The cells in our body are of many different shapes. These shapes are important for the structure and function of tissue. To study the effect of cells shape on the cellular functions (for example differentiation and migration) in lab, cells are grown on proteins, printed in different shapes on flat surface (plastic or gel). The method used for printing protein on the surface using stamps is called microcontact printing. Photolithography, a technique that employs light as a chisel to etch, is usually used to fabricate the mould for these stamps. However, this method requires expertise and is quite expensive. It also needs high-end, sophisticated equipment and depends on using light-sensitive material.
In our study, we made two types of stamps using readily available materials like polystyrene beads and syringe needles as moulds. Polydimethylsiloxane (PDMS, elastic rubber like material) was used to fabricate the stamps which were then used to get the protein pattern. These PDMS cylinders could also be bent to create patterns with curves.
When we cultured mouse myoblast cells on the protein islands created using the two types of stamps, we observed that cells attached only to the protein islands and were healthy. This method of stamp fabrication is easy and requires less expertise compared to traditional lithography. However, the most significant advantage of the proposed approach is its low cost. The PDMS stamps made using novel approach cost mere ₹350 with no requirements for maintenance of equipment. On the contrary, stamps made using photolithography cost around ₹1500 a piece, with additional equipment costs adding to lakhs of rupees annually. An additional advantage of using stamp fabrication methods described in our study is that same stamp can be used to print patterns of varying sizes as they can be flattened by applying pressure, thus increasing their surface area. Finally, we can also create stamps of different curved structure which is otherwise challenging in conventional lithography. This will help research labs with low funding to expand their field of research.
Acknowledgements
This work was supported by Wellcome Trust-DBT India Alliance (Project #IA/E/11/1/500419), IITB Seed Grant (14IRCCSG002) and Department of Chemical Engineering, IIT Bombay. 60 μm stamp was fabricated and donated by Prof. V. Kumaran, IISc and his student Dr. Mohan K Verma. We thank Dr. Jyotsna Dhawan, InStem for generously donating the cells.
Publication details:
Low Cost and Lithography-free Stamp fabrication for Microcontact Printing, Akshada J. Khadpekar, Moin Khan, Abhishek Sose & Abhijit Majumder, Published in Scientific Reports 9, 2019.