Simple droplet microfluidics platform for drug screening on cancer spheroids.

3D in vitro biological systems are progressively replacing 2D systems to increase the physiological relevance of cellular studies. Microfluidics-based approaches can be powerful tools towards such biomimetic systems, but often require high-end complicated and expensive processes and equipment for microfabrication. Herein, a drug screening platform is proposed, minimizing technicality and manufacturing steps. It provides an alternate way of spheroid generation in droplets in tubes. Droplet microfluidics then elicit multiple droplets merging events at programmable times, to submit sequentially the spheroids to chemotherapy and to reagents for cytotoxicity screening. After a comprehensive study of tumorogenesis within the droplets, the system is validated for drug screening (IC50) with chemotherapies in cancer cell lines as well as cells from a patient-derived-xenografts (PDX). As compared to microtiter plates methods, our system reduces the initial number of cells up to 10 times and opens new avenues towards primary tumors drug screening approaches.

A simple acoustofluidic chip for microscale manipulation using evanescent Scholte waves.

Acoustofluidics is acknowledged as a powerful tool offering a contactless and label-free manipulation of fluids, micro-beads, and living cells. To date, most techniques rely on the use of propagating acoustic waves and take advantage of the associated acoustic radiation force in standing or progressive fields. Here, we present a new approach based on the generation of an evanescent acoustic field above a substrate. This field is obtained by means of subsonic interfacial waves giving rise to a well-defined standing wave pattern. By both imaging and probing the evanescent acoustic field, we show that these interfacial waves are guided waves known as quasi-Scholte acoustic waves. Scholte waves present very interesting features for applications in acoustofluidics. Namely, they confine the acoustic energy to the vicinity of the surface, they are nearly lossless and thus can propagate over long distances along the substrate, and finally they do not require any particular material for the substrate. With a very simple and low-cost device we show several examples of applications including patterning lines or arrays of cells, triggering spinning of living cells, and separating plasma from RBC in a whole blood microdroplet.