Development of biomedical devices using 3D printing for cell culture and drug testing

In the last decade, biomedical research has been mainly dedicated to the development of new microfluidic devices that can be used in medical, biological, and pharmacological applications. These miniaturized systems contain micrometer chambers and channels for the flow or containment of fluids, therefore excellent for the fabrication of 3D lab-on-chip for cell cultures and biological analysis. In this regard, it was necessary to promote new large-scale production technologies that were profitable in terms of cost and time. The techniques of 3D Printing, or Additive Manufacturing, are an advantageous alternative to traditional manufacturing techniques of microfluidic platforms. All this is allowed by its promising properties, such as high precision, the reduction of production waste, the possibility of manufacturing complex components in a short time. This work focused on the 3D-printing of silicone-based microfluidic chips through Digital Light Processing (DLP) technology, which promotes 3D printing by means of a photopolymerization triggered by UltraViolet radiation. The resin chosen is the TEGORad 2800, an acrylate polydimethylsiloxane copolymer, which can be easily used to prepare printable and photoreticulable formulations. In order for radical photopolymerization to take place, it is necessary to prepare formulations containing a photoinitiator capable of absorbing the radiation used and promoting the formation of radicals capable of reacting with the acrylate monomer of TEGORad. In addition, additive compounds, such as dyes, are added with the aim of absorbing light radiation and improving the control of the crosslinking reaction. In the biomedical field, in addition to the need for a more accurate and rapid production, the choice of resin is particularly delicate to obtain the most suitable properties of biocompatibility, optical transparency, mechanical flexibility, chemical stability, and absence of cytotoxicity. In this regard, the devices are subjected to washing and sterilization protocols which guarantee the removal of unreacted toxic material or excess dye that could invalidate cell viability. To evaluate cell viability and proliferation, a colorimetric assay (MTT) was carried out. It allows, by means of a fluorescence spectrophotometer, to observe the amount of live cells after several Time Points. The devices obtained have high optical transparency, a very useful property to be able to promote imaging techniques and to control the flow of drug-like in the micrometric channels. They also have good flexibility, typical of silicone materials. Furthermore, genotoxicity tests are performed to evaluate, despite the cell viability is verified, a possible modification or damage at the DNA level. Finally, flow experiments of a drug-like solution ( Rhodamine G6) were done in the microfluidic chip to evaluate the percentage of absorption of the device, which should ideally be zero. In order to ensure in vitro pharmacological tests that the set dose is actually detected by the target cells. TEGORad 2800 could be a good candidate for the realization of microfluidic devices by means of 3D Printing for cell cultures, analytical and diagnostic tests in the laboratory, or in vitro pharmacological experiments. It could replace the use of Polydimethylsiloxane (PDMS), the transparent elastomer most used in the production of microfluidic platforms manufactured by cast molding, which highlighted some limitations in large-scale production.