Staff member

Roberto Paoli

Postdoctoral Researcher
+34 934037185/21860
Staff member publications

Paoli, R., Bulwan, M., Castaño, O., Engel, E., Rodriguez-Cabello, J. C., Homs-Corbera, A., Samitier, J., (2020). Layer-by-layer modification effects on a nanopore's inner surface of polycarbonate track-etched membranes RSC Advances 10, (59), 35930-35940

The control of the morphology, as well as the physical and chemical properties, of nanopores is a key issue for many applications. Reducing pore size is important in nanopore-based sensing applications as it helps to increase sensitivity. Changes of other physical properties such as surface net charge can also modify transport selectivity of the pores. We have studied how polyelectrolyte layer-by-layer (LBL) surface modification can be used to change the characteristics of nanoporous membranes. Studies were performed with a custom made three-dimensional multilayer microfluidic device able to fit membrane samples. The device allowed us to efficiently control LBL film deposition over blank low-cost commercially available polycarbonate track-etched (PCTE) membranes. We have demonstrated pore diameter reduction and deposition of the layers inside the pores through confocal and SEM images. Posterior impedance measurement studies served to evaluate experimentally the effect of the LBL deposition on the net inner nanopore surface charge and diameter. Measurements using direct current (DC) and alternative current (AC) voltages have demonstrated contrasted behaviors depending on the number and parity of deposited opposite charge layers. PCTE membranes are originally negatively charged and results evidenced higher impedance increases for paired charge LBL depositions. Impedance decreased when an unpaired positive layer was added. These results showed a different influence on the overall ion motility due to the effect of different surface charges. Results have been fit into a model that suggested a strong dependence of nanopores' impedance module to surface charge on conductive buffers, such as Phosphate Buffer Saline (PBS), even on relatively large nanopores. In AC significant differences between paired and unpaired charged LBL depositions tended to disappear as the total number of layers increased.

Valls-Margarit, M., Iglesias-García, O., Di Guglielmo, C., Sarlabous, L., Tadevosyan, K., Paoli, R., Comelles, J., Blanco-Almazán, D., Jiménez-Delgado, S., Castillo-Fernández, O., Samitier, J., Jané, R., Martínez, Elena, Raya, Á., (2019). Engineered macroscale cardiac constructs elicit human myocardial tissue-like functionality Stem Cell Reports 13, (1), 207-220

In vitro surrogate models of human cardiac tissue hold great promise in disease modeling, cardiotoxicity testing, and future applications in regenerative medicine. However, the generation of engineered human cardiac constructs with tissue-like functionality is currently thwarted by difficulties in achieving efficient maturation at the cellular and/or tissular level. Here, we report on the design and implementation of a platform for the production of engineered cardiac macrotissues from human pluripotent stem cells (PSCs), which we term “CardioSlice.” PSC-derived cardiomyocytes, together with human fibroblasts, are seeded into large 3D porous scaffolds and cultured using a parallelized perfusion bioreactor with custom-made culture chambers. Continuous electrical stimulation for 2 weeks promotes cardiomyocyte alignment and synchronization, and the emergence of cardiac tissue-like properties. These include electrocardiogram-like signals that can be readily measured on the surface of CardioSlice constructs, and a response to proarrhythmic drugs that is predictive of their effect in human patients.

Keywords: Cardiac tissue engineering, CardioSlice, ECG-like signals, Electrical stimulation, Heart physiology, Human induced pluripotent stem cells, Perfusion bioreactor, Tissue-like properties

Sierra-Agudelo, J. N., Figueras, L., Mir, M., Paoli, R., Rodríguez-Trujillo, R., Samitier, J., (2019). Microfluidic techniques for circulating tumour cells separation C3 - Proceedings of the NewTech'19 5th World Congress on New Technologies , International ASET Inc. (Lisboa, Portugal) ICBB 108, 1-2

Liquid biopsy has become a promising technique for early cancer detection, molecular stratification, detecting treatment relapse, monitoring treatment response and tumor evolution, as well as establishing a personalized treatment program. Currently, this technique is based on the analysis of circulating tumor cells (CTCs), circulating tumor DNA (ctDNA), or tumor-derived extracellular vesicles present in blood [1]. The possibility to process small blood samples represent an excellent approach to monitor the disease course without obtaining tissue directly from the tumor. The alternative results in lower costs with a non-invasive process and the possibility to detect the condition in earlier stages, which would have a great incidence in morbidity rates. Nevertheless, one of the most relevant challenge in this field involves the processing and analyzing of CTCs, due to their low amount in peripheral blood (1 to 100 CTCs per 109 blood cells) [2]. Thus, a highly specialized enrichment method is necessary to harvest high-purity and viable CTCs suitable for subsequent molecular analysis. Nowadays, the approaches for isolating CTCs from blood samples are limited due to high cell contamination rates or substantial loss of cancer cells, and high cost methods. In order to overcome these limitations, microfluidic devices have been designed for isolating CTCs based on their intrinsic properties like density, size, deformability and difference in membrane protein expression [3]. Based on the properties mentioned above, we developed lab-on-a-chip (LOC) platforms using different fabrication techniques such as soft lithography and 3D-printing. The devices combine hydrodynamic sorting, inertial forces and/or cell deformability based on differences in young modulus values between normal blood cells and CTCs. In our method, the use of hydrodynamic sorting can efficiently divide target cells and other cells into different groups by size and guide their movement in their respective trajectories [4]. For developing our CTCs isolation system, we first manufactured a simple microfluidic device composed by two different inlets, one of them use for the blood sample and another one for the focusing liquid (phosphate buffered saline). Our preliminary results revealed that the device can efficiently focus CTCs and separate them from most of the blood cells. Indeed, experiments performed with whole blood samples from healthy donors and polystyrene particles of 30 μm as a CTCs model showed that the particles were correctly recovered (100%), with a very high red blood cell depletion (99.3%). Depletion of white blood cells, however, was not as high (87%) due to the inherent overlap in size with CTCs. In order to overcome the limitations of the previous device, we manufactured a second system designed to capture the remaining leukocytes using an affinity-binding principle. The device includes a herringbone structure with microfabricated ridges placed on the roof of the channel [5]. These structures produce a transverse component in the flow, subsequently helical streamlines are generated, and an increase in the surface interaction with cells takes place. One of the most relevant features of this device is the surface modification with a Self-assembled monolayer (Biotin-PEG-thiol) and a Biotin-PEGOH as an additional blocking agent in the chip surface. Thus, CD45-antibody is immobilized in the inner channel surface to capture Leucocytes and obtaining a high purity CTC sample. This kind of surface modification has several advantages, such as, a better antibody orientation, homogeneous antibody distribution in the surface and long-term stability [6]. In conclusion, we have developed a set of microfluidic devices that, based on hydrodynamic inertial effects are capable of isolating circulant tumor cells from high concentrated blood samples. The devices are fabricated from polymeric biocompatible materials and using low-cost techniques. The proposed devices will pave the way to the development of lowcost compact diagnostic systems for early cancer dete tion.

Paoli, R., Samitier, J., (2016). Mimicking the kidney: A key role in organ-on-chip development Micromachines , 7, (7), 126

Pharmaceutical drug screening and research into diseases call for significant improvement in the effectiveness of current in vitro models. Better models would reduce the likelihood of costly failures at later drug development stages, while limiting or possibly even avoiding the use of animal models. In this regard, promising advances have recently been made by the so-called "organ-on-chip" (OOC) technology. By combining cell culture with microfluidics, biomedical researchers have started to develop microengineered models of the functional units of human organs. With the capacity to mimic physiological microenvironments and vascular perfusion, OOC devices allow the reproduction of tissue- and organ-level functions. When considering drug testing, nephrotoxicity is a major cause of attrition during pre-clinical, clinical, and post-approval stages. Renal toxicity accounts for 19% of total dropouts during phase III drug evaluation-more than half the drugs abandoned because of safety concerns. Mimicking the functional unit of the kidney, namely the nephron, is therefore a crucial objective. Here we provide an extensive review of the studies focused on the development of a nephron-on-chip device.

Keywords: Disease model, Drug discovery, Kidney, Nephron-on-chip, Organ-on-chip