Lucio Isa

Last Name

Isa

First Name

Lucio

ORCID

0000-0001-6731-9620

Organisational unit

09455 - Isa, Lucio / Isa, Lucio

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Publications 1 - 10 of 164

Direct, Robust Technique for the Measurement of Friction between Microspheres
Fernandez, Nicolas; Cayer-Barrioz, Juliette; Isa, Lucio; et al. (2015)
Langmuir
Multi-compartment supracapsules made from nano-containers towards programmable release
Hu, Minghan; Reichholf, Nico; Xia, Yanming; et al. (2022)
Materials Horizons
The assembly of nanomaterials into suprastructures offers the possibility to fabricate larger scale functional materials, whose inner structure strongly influences their functionality for a vast range of applications. In spite of the many current strategies, achieving multi-compartment structures in a targeted and versatile way remains highly challenging. Here, we describe a controllable and straightforward route to create uniform suprastructured materials with a multi-compartmentalized architecture by confining primary nanocapsules into droplets using a cross-junction microfluidic device. Following solvent evaporation from the droplets, the nanocapsules spontaneously assemble into precisely sized multi-compartment particles, which we term supracapsules. Thanks to the process, each spatially separated nanocapsule unit retains its cargo and functionalities within the resulting supracapsules. However, new collective properties emerge, and, particularly, programmable release profiles that are distinct from those of single-compartment capsules. Finally, the suprastructures can be disassembled into single-compartment units by applying ultra-sonication, switching their release to a burst-release mode. These findings open up exciting opportunities to fabricate multi-compartment suprastructures incorporating diverse functionalities for materials with emerging properties.
Dual-Laser Optical Tweezers for Photothermal Analysis of Hybrid Microgels
Jung, Se-Hyeong; Zhang, Chi; Stauffer, Nick; et al. (2026)
Advanced Science
Soft actuators that respond to external stimuli play a fundamental role in microscale robotics, active matter, and bio-inspired systems. Among these actuators, photo-thermal hybrid microgels (HMGs) containing plasmonic nanoparticles enable rapid, spatially controlled actuation via localized heating. Understanding their dynamic behavior at the single-particle level is crucial for optimizing performance. However, traditional bulk characterization methods such as dynamic light scattering (DLS) provide only ensemble-averaged data, thereby limiting analytical insights. Here, a dual-laser optical tweezers approach is introduced for real-time, single-particle analysis of HMGs under controlled light exposure. Combining direct imaging and mean-squared displacement (MSD) analysis, our method quantifies the precise laser power required for actuation and accurately tracks the particle size. The results are benchmarked against dual-laser DLS, demonstrating comparable precision while offering the unique advantage of single-actuator resolution. Thus, this method provides a robust platform for precise optimization of programmable actuators with applications in soft robotics, microswimmers, and biomedical devices.
Dynamically shaping the surface of silica colloids
Niggel, Vincent; Hsu, Chiao-Peng; Isa, Lucio (2022)
Soft Matter
Surface roughness is an important design parameter to influence the processing of particle-based materials. Current methods to synthesize rough particles present some limitations, e.g. low yield, relative methodological complexity, requirements of multiple steps, or poor roughness control. Here, we thoroughly investigate a facile synthesis route where two silanes, tetraethyl orthosilicate (TEOS) and vinyltrimethoxysilane (VTMS), are added in one pot to form silica particles with controlled corrugated surfaces. We first show that the morphology of these particles can be defined by regulating the amount and ratio of the two silane precursors and by adjusting the concentration of ammonia during synthesis. We characterize the surface topography of the particles using atomic force microscopy and show a direct correlation between surface roughness and the synthesis conditions. Furthermore, we carry out an in situ observation of the evolution of surface morphology and propose a mechanism for surface structuring that hinges on the formation of silane droplets, followed by the preferential hydrolysis/condensation reaction of VTMS starting from the droplet surface and evolving towards the center. The exchange of liquid from the droplets through the VTMS shell leads to stress accumulation and wrinkling/buckling of the particles. Moreover, we explicitly show that osmotic imbalances between the inside and the outside of the droplets regulate their shrinking. We therefore demonstrate that exchanging solvents has a comparable impact to adjusting silane and ammonia content in defining the particle shape and that this synthesis route is highly dynamical. Finally, we demonstrate that it is possible to incorporate fluorescent dyes during synthesis to enable future studies on the impact of surface roughness on dynamic processes, including shear, via direct high-resolution imaging. Our findings show that the mechanism for wrinkling and buckling in colloidal silica particles follows a general scheme found in a broad range of systems, from liposomes and polymeric capsules to Pickering emulsion droplets.
Tuning Interparticle Hydrogen Bonding in Shear-Jamming Suspensions: Kinetic Effects and Consequences for Tribology and Rheology
James, Nicole M.; Hsu, Chiao-Peng; Spencer, Nicholas D.; et al. (2019)
The Journal of Physical Chemistry Letters
Tuning particle aspect ratio and surface roughness to modulate properties in colloidal gels
Müller, Florence J.; Yang, Keyu; Isa, Lucio; et al. (2025)
Journal of Colloid and Interface Science
Hypothesis: Particle shape and surface roughness may have synergistic effects on particle network formation in colloidal gels. Particles with an aspect ratio greater than one have orientation-dependent interactions with neighboring particles compared to spheres, making their interactions highly sensitive to rotational dynamics. By adding surface roughness, we add non-central surface forces and expect to further constrain particle rotation, potentially enhancing the stability and rigidity of networks formed by these particles. Experiments: To this end, smooth and rough particles of different aspect ratios were synthesized and grafted with an octadecyl layer to form a thermoreversible gel in tetradecane. The gels were characterized using rheological and optical methods. Findings: Surface roughness was found to reduce the percolation threshold and improve sedimentation stability, though its impact diminishes with increasing aspect ratio. Rough particles formed more homogeneous networks, as surface roughness restricts the excluded-volume-driven local alignment in smooth systems. Consequently, elasticity and yielding behavior are more strongly influenced by aspect ratio in smooth rod gels than in rough rod gels.
Adsorption and Microstructure of Core-Shell Nanoparticles at Liquid-Liquid Interfaces
Isa, Lucio (2013)
Chimia
Stress Contributions in Colloidal Suspensions: The Smooth, the Rough, and the Hairy
Schroyen, Bram; Hsu, Chiao-Peng; Isa, Lucio; et al. (2019)
Physical Review Letters
Stabilization mechanism of double emulsions made by microfluidics
Sander, Jonathan S.; Isa, Lucio; Rühs, Patrick A.; et al. (2012)
Soft Matter
Effect of curvature on the diffusion of colloidal bananas
Ulbrich, Justin-Aurel; Fernández Rico, Carla; Rost, Brian; et al. (2023)
Physical Review E
Anisotropic colloidal particles exhibit complex dynamics which play a crucial role in their functionality, transport, and phase behavior. In this Letter, we investigate the two-dimensional diffusion of smoothly curved colloidal rods - also known as colloidal bananas - as a function of their opening angle α. We measure the translational and rotational diffusion coefficients of the particles with opening angles ranging from 0∘ (straight rods) to nearly 360∘(closed rings). In particular, we find that the anisotropic diffusion of the particles varies nonmonotonically with their opening angle and that the axis of fastest diffusion switches from the long to the short axis of the particles when α>180∘. We also find that the rotational diffusion coefficient of nearly closed rings is approximately an order of magnitude higher than that of straight rods of the same length. Finally, we show that the experimental results are consistent with slender body theory, indicating that the dynamical behavior of the particles arises primarily from their local drag anisotropy. These results highlight the impact of curvature on the Brownian motion of elongated colloidal particles, which must be taken into account when seeking to understand the behavior of curved colloidal particles.

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