Nicolas Mackiewicz

Supramolecular Self-Assembly of Amphiphiles on Carbon Nanotubes: A Versatile Strategy for the Construction of CNT/Metal Nanohybrids, Application to Electrocatalysis

Homogeneous coating of carbon nanotubes with metallic nanoparticles was achieved using supramolecular auto-organization of amphiphilic molecules as template. The resulting Pd nanoparticles/carbon nanotube nanohybrids were then evaluated in electrocatalysis experiments, showing superior activity in ethanol oxidation compared to analogous systems.

Drug Delivery and Imaging with Polydiacetylene Micelles

This concept article summarizes our recent findings regarding photopolymerized micelles obtained from the self-assembly of diacetylene-containing amphiphiles. Their synthesis and characterization are presented as well as some biomedical applications, such as tumor imaging and drug delivery. Finally, ongoing studies and future challenges are briefly discussed.

Tumor-targeted polydiacetylene micelles for in vivo imaging and drug delivery.

In vivo tumor targeting and drug delivery properties of small polymerized polydiacetylene (PDA) micelles (∼10 nm) is investigated in a murine MDA-MB-231 xenograft model of breast cancer. Three micelles with different surface coatings are synthesized and tested for their ability to passively target tumor through the enhanced permeability and retention effect. After injection (24 h), fluorescence diffuse optical tomographic imaging indicates a tumor uptake of nearly 3% of the injected dose for the micelles with a 2 kDa poly(ethylene glycol) (PEG)-coating (PDA-PEG2000). The uptake of PDA micelles in tumors is confirmed by co-localization with [(18) F]-fluorodeoxyglucose (FDG) positron emission tomography. Although FDG has a higher diffusion rate in tumors, 40 ± 19% of the retained micelles is co-registered with the tumor volume visualized by FDG. Finally, PDA-PEG2000 micelles are loaded with the hydrophobic anticancer drug paclitaxel and used in vivo to inhibit tumor growth. These findings demonstrate the potential of PDA-PEG2000 micelles for both in vivo tumor imaging and drug delivery applications.

In vivo validation of free-space fluorescence tomography using nuclear imaging

The performance of small animal photonic imaging has been considerably improved since the development of fluorescence diffuse optical tomography (fDOT), which can reconstruct fluorescent probe distribution inside tissue. However, the quantification capabilities of this new technology are still a topic of debate, especially in comparison to classical nuclear imaging techniques. Here, we present a method to in vivo calibrate the quantity and localization of a probe provided by free-space fDOT (where no plate is compressing the mouse) with positron emission tomography (PET) and x-ray computed tomography, respectively. This methodology allowed us to demonstrate a strong linear correlation (R(2)=0.95) between fDOT and PET for probe concentrations ranging from 3 nM to 1 μM in a deep-seated organ.

Colloidal properties of biodegradable nanoparticles influence interaction with amyloid-β peptide.

Alzheimers disease (AD) is a neurodegenerative disorder characterized by the extracellular deposition of amyloid-β peptides (Aβ). During the past few years, promising approaches based on nanotechnologies have emerged to alter Aβ aggregation and its related toxicity. This study aims to investigate the influence of the nanoparticle colloidal properties over the interaction with Aβ peptide 1-42 (Aβ(1-42)). Using capillary electrophoresis with laser-induced fluorescence detection, it was shown that biodegradable poly(ethylene glycol)-block-polylactide (PEG-b-PLA) nanoparticles were able to interact with Aβ(1-42) peptide leading to its uptake in rather short time periods. In addition, we highlighted the crucial role of the nanocarrier colloidal properties on the uptake kinetics. Whereas nanoparticles stabilized by sodium cholate (lower size and higher negative surface charge) gave optimum uptake kinetics, nanoparticles stabilized with others surfactants presented lower interactions. In contrast, PEG density seemed to have no influence on the interaction when sodium cholate was used for the preparation. This study intends to give new insights into Aβ(1-42) peptide interaction with nanoparticulate systems by helping to determine suitable nanoparticle characteristics regarding forthcoming therapeutic strategies against AD.