Dip Pen Lithography of oligonucleotides on flexible substrates for point-of-care malaria disease testing

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The first step for prevention and treatment of diseases is the accurate diagnosis. However, proper diagnostic technologies are notavailable in developing countries due to the lack of reliable electrical power, refrigeration and trained personnel. For this reason,there is an urgent need of low cost, rapid assays not requiring any external support. By coupling such technologies tocommunication infrastructures, healthcare in areas without access to medical personnel would be possible. “Paper” like substratesare ideal for fabricating such devices since they are cheap, easy to degradate after use and compatible with most of existingprinting technologies [1]. We had previously shown the possibility to efficiently deposit oligonucleotides by Dip PenLithography(DPL) onto glass surfaces [2]. In this work, we deposited oligonucleotides on nylon substrate for the fabrication ofbiochips usable for detecting the activity of human topoisomerase I. Subsequently, the chip will be modified to detect the MalariacausingPlasmodium parasites through the detection of Plasmodium topoisomerase I activity [3]. We optimized oligonucleotidesprinting on nylon substrate, obtaining efficient deposition at 10 - 1 uM oligonucleotide concentrations, 70% relative humidity and30% glycerol v/v. We obtained circular spots with diameter in the range of 30 - 50 microns, with the dimension being a function ofdwell time (1s – 20 s). DPL operation needs ultra tiny amounts of DNA (as low as 0.5 uL, 10 - 1 uM concentration) for printingthousands of spots in a single run so reducing material consumption in comparison with standard bioprinting techniques [4]. In afirst set of experiments, the printed oligonucleotides was hybridized with a fluorescence-labelled complementary probe to detectand quantify DNA after DPL deposition. In subsequent experiment, the spotted oligonucleotides generate a topoisomerasesubstrate, which upon reaction with the enzyme will be coupled to a fluorescently labelled oligonucleotide to allow detection of asignal. In conclusion, the combination of DPL and topoisomerase detection onto nylon substrates would be a suitable solution forpoint-of-care diagnostic chips fabrication.
Original languageEnglish
Number of pages1
Publication statusPublished - 2015


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