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PhD Discussion Sessions: Teodora Andrian and Xavier Arqué

Divendres, abril 30, 2021 @ 10:00 am12:00 pm

Correlating super-resolution microscopy and transmission electron microscopy for nanoparticle characterisation

Teodora Andrian, Nanoscopy for nanomedicine group

The functionalization of nanoparticles with surface functional moieties is a key strategy to achieve bioactivity and cell targeting in nanomedicine. The interplay between size and ligand number and distribution is crucial for the formulation performance and needs to be properly characterized to understand nanoparticle structure-activity relations. However, the particle-to-particle heterogeneity poses a serious challenge due to the lack of methods able to measure both size and ligand number and distribution at the same time and at the single particle level. Here we address this issue by introducing a correlative method combining super-resolution microscopy (SRM) and transmission electron microscopy (TEM) imaging. Correlative light and electron microscopy (CLEM) techniques proved their potential in structural biology but to the best of our knowledge, they have not yet been explored for the structural characterization of nanoparticles. Here we apply our super-resCLEM method to characterize the relationship between size and ligand number, and ligand density in PLGA-PEG nanoparticles at the single particle and single-molecule level.  We highlight how heterogeneity found in nanoparticle size can impact ligand distribution, and we discuss the implications on formulation performance. We show how a significant part of the nanoparticle population goes completely undetected in the single-technique analysis, demonstrating that the characterization of nanomaterials using a multiparametric correlative method outplays the information obtained compared to a one-method-at-a-time approach. Using SRM alone, we demonstrated how PEG architecture can influence ligand conjugation efficiency and accessibility. The applicability of our method spans beyond PLGA-PEG nanoparticles and holds great promise for the multiparametric analysis of several other parameters and nanomaterials.

Unraveling the fundamental aspects of enzyme-powered micromotors

Xavier Arqué, Smart Nano-Bio-Devices group

Enzyme-coated micro- and nanomotors self-propel by the biocatalytic conversion of substrates into products and show great promise as actively navigating agents in the fields of biomedicine and environmental applications. However, many of the fundamental aspects underlying enzyme-powered self-propulsion have yet to be fully understood and are crucial for their optimal implementation. Under this framework, this research is focused on elucidating and studying the intrinsic (catalytic turnover or structural flexibility) and extrinsic (bulk and local ionic media) enzymatic properties that lead to an improved active motion powered by bio-catalysis. This is enabled by exploring novel types of both i) enzymes that can act as active motion engines and ii) platforms with appealing properties to be used as chassis of enzymatic micro- and nanomotors. Overall, this work contributes to a better understanding of the mechanism of motion of enzymatic active motion, expands the current library of enzymatic engines and chassis materials available, and provides new insights into the feasibility of implementation of enzyme-powered micro- and nanomotors.

The session will be held online using the GoToMeeting Platform

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Divendres, abril 30, 2021
10:00 am–12:00 pm
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