Pierre Couleaud

Nanoparticles as vehicles for delivery of photodynamic therapy agents

Photodynamic therapy (PDT) in cancer treatment involves the uptake of a photosensitizer by cancer tissue followed by photoirradiation. The use of nanoparticles as carriers of photosensitizers is a very promising approach because these nanomaterials can satisfy all the requirements for an ideal PDT agent. This review describes and compares the different individual types of nanoparticles that are currently in use for PDT applications. Recent advances in the use of nanoparticles, including inorganic oxide-, metallic-, ceramic-, and biodegradable polymer-based nanomaterials as carriers of photosensitizing agents, are highlighted. We describe the nanoparticles in terms of stability, photocytotoxic efficiency, biodistribution and therapeutic efficiency. Finally, we summarize exciting new results concerning the improvement of the photophysical properties of nanoparticles by means of biphotonic absorption and upconversion.

Mannose-targeted mesoporous silica nanoparticles for photodynamic therapy.

Functionalisation of MSN with mannose for PDT applications dramatically improved the efficiency of PDT on breast cancer cells.

Silicalites and Mesoporous Silica Nanoparticles for photodynamic therapy

The synthesis of silicalites and Mesoporous Silica Nanoparticles (MSN), which covalently incorporate original water-soluble photosensitizers for PDT applications is described. PDT was performed on MDA-MB-231 breast cancer cells. All the nanoparticles showed significant cell death after irradiation, which was not correlated with (1)O(2) quantum yield of the nanoparticles. Other parameters are involved and in particular the surface and shape of the nanoparticles which influence the pathway of endocytosis. Functionalization with mannose was necessary to obtain the best results with PDT due to an active endocytosis of mannose-functionalized nanoparticles. The quantity of mannose on the surface should be carefully adjusted as a too high amount of mannose impairs the phototoxicity of the nanoparticles. Fluorescein was also encapsulated in MCM-41 type MSN in order to localize the nanoparticles in the organelles of the cells by confocal microscopy. The MSN were localized in lysosomes after active endocytosis by mannose receptors.

Triazinyl Porphyrin-Based Photoactive Cotton Fabrics: Preparation, Characterization, and Antibacterial Activity

In the present work, we report on the synthesis of cellulose cotton fibers bearing different types of photosensitizers with the aim to prepare new efficient polymeric materials for antimicrobial applications. Anionic, neutral, and cationic amino porphyrins have been covalently grafted on cotton fabric, without previous chemical modification of the cellulosic support, using a 1,3,5-triazine derivative as the linker. The obtained porphyrin-grafted cotton fabrics were characterized by infrared (ATR-FTIR), diffuse reflectance UV-vis (DRUV) spectroscopies, and thermogravimetric analysis (TGA) to confirm the triazine linkage. Antimicrobial activity of porphyrin-cellulose materials was tested under visible light irradiation against Staphylococcus aureus and Escherichia coli . The results showed excellent activity on the Gram-positive bacterium, showing structure-activity relationship, although no photodamage of the Gram-negative microorganism was recorded. A mechanism of bacterial inactivation by photosensitive surfaces is proposed.

Functionalized silica-based nanoparticles for photodynamic therapy

AIM The strategy developed aims to favor the vascular effect of photodynamic therapy by targeting tumor-associated vascularization using peptide-functionalized nanoparticles. We previously described the conjugation of a photosensitizer to a peptide targeting neuropilin-1 overexpressed in tumor angiogenic vessels. MATERIALS & METHODS In this study, we have designed and photophysically characterized a multifunctional nanoparticle consisting of a surface-localized tumor vasculature targeting peptides and encapsulated photodynamic therapy and imaging agents. RESULTS & CONCLUSION The elaboration of these multifunctional silica-based nanoparticles is reported. Nanoparticles functionalized with approximately 4.2 peptides bound to recombinant neuropilin-1 protein. Nanoparticles conferred photosensitivity to cells overexpressing neuropilin-1, providing evidence that the chlorin grafted within the nanoparticle matrix can be photoactivated to yield photocytotoxic effects in vitro.

Multifunctional ultrasmall nanoplatforms for vascular-targeted interstitial photodynamic therapy of brain tumors guided by real-time MRI

Photodynamic therapy (PDT) for brain tumors appears to be complementary to conventional treatments. A number of studies show the major role of the vascular effect in the tumor eradication by PDT. For interstitial PDT (iPDT) of brain tumors guided by real-time imaging, multifunctional nanoparticles consisting of a surface-localized tumor vasculature targeting neuropilin-1 (NRP-1) peptide and encapsulated photosensitizer and magnetic resonance imaging (MRI) contrast agents, have been designed. Nanoplatforms confer photosensitivity to cells and demonstrate a molecular affinity to NRP-1. Intravenous injection into rats bearing intracranial glioma exhibited a dynamic contrast-enhanced MRI for angiogenic endothelial cells lining the neovessels mainly located in the peripheral tumor. By using MRI completed by NRP-1 protein expression of the tumor and brain adjacent to tumor tissues, we checked the selectivity of the nanoparticles. This study represents the first in vivo proof of concept of closed-head iPDT guided by real-time MRI using targeted ultrasmall nanoplatforms. From the clinical editor: The authors constructed tumor vascular peptide targeting multifunctional silica-based nanoparticles, with encapsulated gadolinium oxide as MRI contrast agent and chlorin as a photosensitizer, as a proof of concept novel treatment for glioblastoma in an animal model.

Designed Modular Proteins as Scaffolds To Stabilize Fluorescent Nanoclusters.

Proteins have been used as templates to stabilize fluorescent metal nanoclusters thus obtaining stable fluorescent structures, and their fluorescent properties being modulated by the type of protein employed. Designed consensus tetratricopeptide repeat (CTPR) proteins are suited candidates as templates for the stabilization of metal nanoclusters due to their modular structural and functional properties. Here, we have studied the ability of CTPR proteins to stabilize fluorescent gold nanoclusters giving rise to designed functional hybrid nanostructures. First, we have investigated the influence of the number of CTPR units, as well as the presence of cysteine residues in the CTPR protein, on the fluorescent properties of the protein-stabilized gold nanoclusters. Synthetic protocols to retain the protein structure and function have been developed, since the structural and functional integrity of the protein template is critical for further applications. Finally, as a proof-of-concept, a CTPR module with specific binding capabilities has been used to stabilize gold nanoclusters with positive results. Remarkably, the protein-stabilized gold nanocluster obtained combines both the fluorescence properties of the nanoclusters and the functional properties of the protein. The fluorescence changes in nanoclusters fluorescence have been successfully used as a sensor to detect when the specific ligand was recognized by the CTPR module.

Designed Repeat Proteins as Building Blocks for Nanofabrication

This chapter will focus on the description of protein-based nanostructures. How proteins can be used as molecular units in order to generate complex materials and structures? What are the key aspects to achieve defined final properties, including shape, stability, function, and order at different length scales by modifying the protein sequence at the modular level?As described in other chapters of the book, we will review the basic concepts and the latest achievements in protein engineering toward nanotechnological applications. Particularly in this chapter the main focus will be on a particular type of proteins, repeat proteins. Because of their modular nature, these proteins are better suited to be used as building blocks than other protein scaffolds. First, we describe general concepts of the protein-based assemblies. Then we introduce repeat proteins and describe the properties that will impact their use in nanotechnology. In particular, we focus on a system based on a synthetic protein, the consensus tetratricopeptide repeat (CTPR). We review recent works from other groups and our group in which the potential of these repeat protein scaffolds is exploited for the fabrication of different protein assemblies, and as biomolecular templates to arrange different molecules and nanoscale objects.