Three dimensional cell culture assays is a rapidly emerging approach for biotechnology. In order to address the technical laboratory automation issues, described are some examples showing how piezoelectric dispensing methods have been applied.
These systems are step up to do biochip fabrication, sample processing and image analysis. To do this, the system is run using a browser based operating system which means that the laboratory instrument is also a webserver. The basic models employ 3 seperate Raspi ARMs that run a head camera, stroboscope and operates a motion controller. In addition to the Raspi, it also uses linux formatted small form factor low energy consuming Chromebox that acts as the main webserver, robotic schedular and image processor.
This example demonstrates how cells are mixed with a semi solid matrigel material (alginate) and this can be dispensed accurately on areas that were previously functionalized using the same dispenser. This printing process is based on an aspiration and dispense mode where the samples are aspirated from a microwell plate or tubes which is achieved through the use of a syringe pump. After aspiration, the tips are checked in a stroboscope in order to assess whether the dispensing is stable. It is possible to adjust the voltage, pulse and frequency to optimize the dispensing process. Details about this are here: controllingpiezodispenser.php
After spotting the slides were cultured in petri dishes in a sufficient volume of cell culture media. These cultures grew for 5 days in a standard incubator and after this time the arrays were still intact.
One of the key issues for maintaining viability during the fabrication process is that the cells must not dry out. So fast spotting really helps and also maintaing a near dew point environment (that involves paying attention to the surface temperature and the ambient humidity) is important. Another way to address this problem is also to dispense small gaskets using materials that are easy to dispense yet harden to form small walls. One thing we tried is sol-gel and this example is posted here: solgel-gaskets.php. In this case it is possible to dispense little wells, the spot the array then fill the area with media using another dispenser immediately thereafter.
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