Directed assembly

The micro-contact printing machine Innostamp® has been used to achieve an automated process of large scale, organized and high density deposition of single biomolecules such as DNA strands and actin filaments. A novel capillary assembly module has been implemented in the Innostamp automate for deposition of biomolecules onto a micro-structured PDMS stamp (see Fig.1). This module can be used in place of the inking step commonly used in a micro-contact printing protocol.

 Figure 1: Capillary assembly module inside the Innostamp 40 automate

Figure 2: Schematic representation of capillary assembly and nano-contact priting processes

 

During capillary assembly, the micro-structured stamp is displaced over a droplet of molecules in suspension, which are directed towards the contact line by the fluid flows created upon evaporation. Due to the topographical structuration of the stamp, the molecules are trapped by capillarity, elongated and immobilized at the pre-defined sites (micro-cavities) of the stamp.

The presence of a side camera on the Innostamp allows to precisely adjust the stamp-to-glass distance, “d” on Fig.2, in order for the liquid to slightly brush the stamp surface. The molecules deposition is thus driven by capillary forces only, avoiding any over-squeezing of the droplet which could encourage multiple molecules deposition.

The following step consists in the controlled nano-contact printing of these molecules onto a final substrate. The adjustment of the stamp speed displacement and control of physical parameters such as temperature and humidity rate ensure a high reproducibility in the process. The high precision of the automate rotary head and the ability of multiple printings open up many possibilities in the architectures created.

Advantages:

This technique enables an increase in density, ordering and throughput capacity by generating a single-molecule platform in an automated way allowing massively parallel data collection in real time. Future directions concern adapting the methodology to produce regular arrays of suspended biomolecules such as actin to study molecular motors helical motion or other dynamic physiological processes. We could also envision transposing this nanopatterning scheme by extension to other systems like chromatin for epigenetic purpose.

Figure 3: Assets of the automated technique of directed assembly and main technical achievements

 

Publications:

• A. Cerf, C. Thibault, M. Geneviève, C. Vieu, Ordered arrays of single DNA molecules by a combination of capillary assembly, molecular combing and soft-lithography, Microelectronic Engineering, 2009, Volume 86, p1419-1423
• Cayron, H., Berteloite, B., Vieu, C., Paveau, V., Cau, J.-C., and Cerf, A. (2015). Controlled deposition and multi-layer architecturing of single biomolecules using automated directed capillary assembly and nano-contact printing processes. Microelectron. Eng. 135, 1–6.

Patents:

• Method of Detecting and Quantifying Analytes of Interest in a Liquid and Implementation Device US2012070911

Thesis:

• M. Genevieve, Thèse INSA, Toulouse, 2009.
• A. Cerf, Thèse INSA, Toulouse, 2009.
• F. Seichepine, Thèse INSA, Toulouse, 2012.