Lourdes Basabe-Desmonts

Hierarchical self-assembly of gold nanoparticles into patterned plasmonic nanostructures.

The integration of nanoparticle superstructures into daily life applications faces major challenges including the simplification of the self-assembly process, reduced cost, and scalability. It is, however, often difficult to improve on one aspect without losing on another. We present in this paper a benchtop method that allows patterning a macroscopic substrate with gold nanoparticle supercrystals in a one-step process. The method allows parallelization, and patterned substrates can be made with high-throughput. The self-assembly of a variety of building blocks into crystalline superstructures takes place upon solvent evaporation, and their precise placement over millimeter scale areas is induced by confinement of the colloidal suspension in micron-sized cavities. We mainly focus on gold nanorods and demonstrate their hierarchical organization up to the device scale. The height of the formed nanorod supercrystals can be tuned by simply varying nanorod concentration, so that the topography of the substrate and the resulting optical properties can be readily modulated. The crystalline order of the nanorods results in homogeneous and high electric field enhancements over the assemblies, which is demonstrated by surface-enhanced Raman scattering spectroscopy.

Combinatorial Method for Surface-Confined Sensor Design and Fabrication

The procedure for the combinatorial fabrication of new sensing materials for cations and anions based on self-assembled monolayers (SAM) is discussed. A library of different sensitive substrates is generated by sequential deposition of fluorophores and small ligand molecules onto an amino-terminated SAM coated glass. The preorganization provided by the surface avoids the need for complex receptor design, allowing for a combinatorial approach to sensing systems based on individually deposited small molecules. Additionally the sensing system has been miniaturized to the microscale using microcontact printing and integrating the sensory SAMs on the walls of microchannels.

Microtechnologies for Cell Microenvironment Control and Monitoring

A great breadth of questions remains in cellular biology. Some questions cannot be answered using traditional analytical techniques and so demand the development of new tools for research. In the near future, the development of highly integrated microfluidic analytical platforms will enable the acquisition of unknown biological data. These microfluidic systems must allow cell culture under controlled microenvironment and high throughput analysis. For this purpose, the integration of a variable number of newly developed micro- and nano-technologies, which enable control of topography and surface chemistry, soluble factors, mechanical forces and cell–cell contacts, as well as technology for monitoring cell phenotype and genotype with high spatial and temporal resolution will be necessary. These multifunctional devices must be accompanied by appropriate data analysis and management of the expected large datasets generated. The knowledge gained with these platforms has the potential to improve predictive models of the behavior of cells, impacting directly in better therapies for disease treatment. In this review, we give an overview of the microtechnology toolbox available for the design of high throughput microfluidic platforms for cell analysis. We discuss current microtechnologies for cell microenvironment control, different methodologies to create large arrays of cellular systems and finally techniques for monitoring cells in microfluidic devices.

Biomolecule storage on non-modified thermoplastic microfluidic chip by ink-jet printing of ionogels.

This paper reports an innovative technique for reagents storage in microfluidic devices by means of a one-step UV-photoprintable ionogel-based microarray on non-modified polymeric substrates. Although the ionogel and the ink-jet printing technology are well published, this is the first study where both are used for long-term reagent storage in lab-on-a-chip devices. This technology for reagent storage is perfectly compatible with mass production fabrication processes since pre-treatment of the device substrate is not necessary and inkjet printing allows for an efficient reagent deposition process. The functionality of this microarray is demonstrated by testing the release of biotin-647 after being stored for 1 month at room temperature. Analysis of the fluorescence of the ionogel-based microarray that contains biotin-647 demonstrated that 90% of the biotin-647 present was released from the ionogel-based microarray after pumping PBS 0.1% Tween at 37 °C. Moreover, the activity of biotin-647 after being released from the ionogel-based microarray was investigated trough the binding capability of this biotin to a microcontact printed chip surface with avidin. These findings pave the way for a novel, one-step, cheap and mass production on-chip reagents storage method applicable to other reagents such as antibodies and proteins and enzymes.

Combinatorial libraries of fluorescent monolayers on glass

Fluorescent self-assembled monolayers (SAMs) on glass surfaces are discussed as new sensing materials for metal ions and inorganic anions. The sensing SAMs are created by sequential deposition of two building blocks, a fluorophore and a ligand molecule onto an amino terminated SAM on glass slides. A large number of different systems can be fabricated by combinatorial techniques and parallel synthesis. A collection of sensing SAMs constitute a cross-reactive sensor array, with which analytes can be identified by differential sensing using the collective response of the SAMs array, instead of the individual response of a single SAM. Arrays of fluorescent SAMs have been produced both in microtiter plate and in multichannel microfluidic chip formats. Additionally, the glass substrates coated with fluorescent SAMs have been used as substrates for chemical patterning.

CHAPTER 9:Applications of Ionic Liquid Materials in Microfluidic Devices

“Lab-on-a-chip” (LOC) and microfluidics enable the manipulation of fluids at small length scales (from micrometers to millimeters). These systems often have well-defined fabrication processes and are capable of integrating multiple functional elements, to provide complete sample-in/answer-out systems. Nevertheless, the development of fully integrated microfluidic devices still faces some considerable obstacles, including fluidic control, miniaturisation and high costs. Due to their unique properties, ionic liquids have arisen as smart solutions to circumvent some of the hurdles facing current LOC technologies. They can directly benefit microfluidic devices by aiding miniaturised fabrication and passive microfluidic elements for fluid control, sensing and sample storage. Improved chemical reactions and separation, in addition to power generation, temperature control, and electrowetting show potential for reducing manufacturing costs and widening market possibilities. In this chapter we will review and discuss the fundamental applications of ionic liquids within microfluidic systems.