Category Archives: Publication


Hot off the press

Our new paper has been just published in Biosensors and Bioelectronics!

Hanson, K. L., Fulga, F., Dobroiu, S., Solana, G., Kašpar, O., Tokárová, V., Nicolau, D. V.

Polymer surface properties control the function of heavy meromyosin in dynamic nanodevices



The actin-myosin system, responsible for muscle contraction, is also the force-generating element in dynamic nanodevices operating with surface-immobilized motor proteins. These devices require materials that are amenable to micro- and nano-fabrication, but also preserve the bioactivity of molecular motors. The complexity of the protein-surface systems is greatly amplified by those of the polymer-fluid interface; and of the structure and function of molecular motors, making the study of these interactions critical to the success of molecular motor-based nanodevices. We measured the density of the adsorbed motor protein (heavy meromyosin, HMM) using quartz crystal microbalance; and motor bioactivity with ATPase assay, on a set of model surfaces, i.e., nitrocellulose, polystyrene, poly(methyl methacrylate), and poly(butyl methacrylate), poly(tert-butyl methacrylate). A higher hydrophobicity of the adsorbing material translates in a higher total number of HMM molecules per unit area, but also in a lower uptake of water, and a lower ratio of active per total HMM molecules per unit area. We also measured the motility characteristics of actin filaments on the model surfaces, i.e., velocity, smoothness and deflection of movement, determined via in vitro motility assays. The filament velocities were found to be controlled by the relative number of active HMM per total motors, rather than their absolute surface density. The study allowed the formulation of the general engineering principles for the selection of polymeric materials for the manufacturing of dynamic nanodevices using protein molecular motors.



Hot of the press

Our article has been just published in the Lab on a Chip!

Confinement of Water Droplets on Rectangular Micro/Nano-arrayed Surfaces

Ondřej Kašpar,   Hailong Zhang,  Viola Tokárová,  Reinhard Ingemar Boysen,   Gema Rius Suñé,   Xavier Borrise,  Francesc Pérez-Murano,   Milton Thomas Hearn and  Dan Nicolau  

Micro-patterned surfaces with alternate, hydrophilic, and hydrophobic rectangular areas, effectively confine water droplets down to attolitre volumes. The contact angle, volume, and geometry of the confined droplets as a function of the geometry and physico-chemical properties of the confining surfaces have been determined by phenomenological simulations, validated by Atomic Force Microscopy measurements. The combination between experiments and simulations can be used for the purposeful design of surface-addressable hydrophobicity arrays employed in digital microfluidics and high throughput screening nanoarrays.

DOI: 10.1039/C6LC00622A
Accepted 27 May 2016
First published online 27 May 2016



Parallel computation with molecular-motor-propelled agents in nanofabricated networks

Who’s talking about our research? Please click here!

Overview of attention for article published in Proceedings of the National Academy of Sciences of the United States of America, February 2016

Score: In the top 5% of all research outputs scored by Altmetric


“The digital age is dawning. The bio computer will make digital look like the abacus.

Science MArch

Science – Replacing electrons with filaments

Science MArch


Replacing electrons with filaments

Science  11 Mar 2016:
Vol. 351, Issue 6278, pp. 1163-1164
DOI: 10.1126/science.351.6278.1163-g



Hot off the press

Parallel computation with molecular-motor-propelled agents in nanofabricated networks

Dan V. Nicolau Jr., Mercy Lard, Till Korten, Falco C. M. J. M. van Delft, Malin Persson, Elina Bengtsson, Alf Månsson, Stefan Diez, Heiner Linke and Dan V. Nicolau

Freely available online through the PNAS open access option


The combinatorial nature of many important mathematical problems, including nondeterministic-polynomial-time (NP)-complete problems, places a severe limitation on the problem size that can be solved with conventional, sequentially operating electronic computers. There have been significant efforts in conceiving parallel-computation approaches in the past, for example: DNA computation, quantum computation, and microfluidics-based computation. However, these approaches have not proven, so far, to be scalable and practical from a fabrication and operational perspective. Here, we report the foundations of an alternative parallel-computation system in which a given combinatorial problem is encoded into a graphical, modular network that is embedded in a nanofabricated planar device. Exploring the network in a parallel fashion using a large number of independent, molecular-motor-propelled agents then solves the mathematical problem. This approach uses orders of magnitude less energy than conventional computers, thus addressing issues related to power consumption and heat dissipation. We provide a proof-of-concept demonstration of such a device by solving, in a parallel fashion, the small instance {2, 5, 9} of the subset sum problem, which is a benchmark NP-complete problem. Finally, we discuss the technical advances necessary to make our system scalable with presently available technology.

Actin filaments exploring the {2, 5, 9} device. The movie shows a time lapse of 200 typical fluorescence micrographs of actin filaments (shown in white) moving through a network (shown in blue) encoding the SSP with the set {2, 5, 9}. Exits labeled with green numbers represent correct results, and magenta numbers represent incorrect results. Below each exit, the number of actin that has arrived there is shown in white. The image of the network was obtained from an optical micrograph of the device and cropped to fit to the fluorescence image. Blurred objects passing over the network are actin filaments floating by in the solution. A background subtraction and contrast enhancement was performed evenly across the images with the use of ImageJ (


Hot off the press

Micro-contact printing, μCP, is a well-established soft-lithography technique for printing biomolecules. μCP uses stamps made of Poly(dimethylsiloxane), PDMS, made by replicating a microstructured silicon master fabricated by semiconductor manufacturing processes. One of the problems of the μCP is the difficult control of the printing process, which, because of the high compressibility of PDMS, is very sensitive to minute changes in the applied pressure. This over-sensitive response leads to frequent and/or uncontrollable collapse of the stamps with high aspect ratios, thus decreasing the printing accuracy and reproducibility. Here we present a straightforward methodology of designing and fabricating PDMS structures with an architecture which uses the collapse of the stamp to reduce, rather than enlarge the variability of the printing. The PDMS stamp, organized as an array of pyramidal micro-posts, whose ceiling collapses when pressed on a flat surface, replicates the structure of the silicon master fabricated by anisotropic wet etching. Upon application of pressure, depending on the size of, and the pitch between, the PDMS pyramids, an air gap is formed surrounding either the entire array, or individual posts. The printing technology, which also exhibits a remarkably low background noise for fluorescence detection, may find applications when the clear demarcation of the shapes of protein patterns and the distance between them are critical, such as microarrays and studies of cell patterning.

This article is open access - enjoy it! :)


BµF Team