-L'imagerie par bioluminescence est une technologie d'imagerie optique basée sur la détection de ... more -L'imagerie par bioluminescence est une technologie d'imagerie optique basée sur la détection de photons produits par une réaction biologique entre un substrat et une enzyme dans les tissus vivants. Cette technique d'imagerie, peu bruitée, est utilisée dans de nombreux domaines de la recherche biomédicale et notamment en oncologie préclinique. Le flux de photonsémis par une tumeur est liéà son volume et sonétat métabolique, nécessitant une localisation précise de celle-ci. Certaines expériences impliquent la visualisation de signaux multiples (par exemple 2 tumeurs) sur le même animal ce qui rend leur quantification difficile car la délimitation manuelle de la région d'intérêt (ROI) doit etre plus fine et est le plus souvent arbitraire. Dans ce travail, nousétudions l'utilisation de la décomposition factorielle par Factorisation Non-Négative de Matrice (Non-Negative Matrix Factorization, NMF) comme méthode de séparation des sources afin de permettre une quantification plus précise de chaque tumeur sans a priori spatial.
After excitation in the biological transparency window, chromium-doped zinc gallate nanoparticles... more After excitation in the biological transparency window, chromium-doped zinc gallate nanoparticles (ZGO NPs) emit near-infrared luminescence for more than an hour, allowing long-term imaging to be performed without background autofluorescence. However, these nanoparticles are recognized in just a few minutes by serum proteins and are then trapped in the liver. In this article, we put forth that liver uptake can be delayed when coating the surface of ZGO NPs with zwitterions. We focused on the use of a very small zwitterion molecule of 330 Da derived from sulfobetaine silane (SBS) and its grafting in one step and in water onto zinc gallate nanoparticles, and we compared the colloidal stability, the in vitro interactions with serum proteins, and the biodistribution in mice with PEGylated ZGO NPs (5000 Da) prepared in two steps in organic solvent. In vitro quantification of serum protein adsorption suggests that the similarity between the sulfobetaine and the cell membrane is enough to ...
In Vivo Electrochemical Detection of Nitric Oxide in Tumor-Bearing Mice
Analytical Chemistry, Dec 20, 2006
Interest in elucidating the mechanisms of action of various classes of anticancer agents and expl... more Interest in elucidating the mechanisms of action of various classes of anticancer agents and exploring the pathways of the induced-nitric oxide (NO) release provides an impetus to conceive a better designed approach to locally detect NO in tumors, in vivo. We report here on the first use of an electrochemical sensor that allows the in vivo detection of NO in tumor-bearing mice. In a first step, we performed the electrochemical characterization of a stable electroactive probe, K4Fe(CN)6, directly injected into the liquid microenvironment especially created around the electrode in the tumor. Second, the ability of the inserted electrode system to detect the presence of NO itself in the tumoral tissue was achieved by using the chemically modified Pt/Ir electrode as NO sensor and two NO donor molecules: diethylammonium (Z)-1-(N,N-diethylamino)diazen-1-ium 1,2-diolate (DEA-NONOate) and (Z)-1-[N-(2-aminopropyl)-N-(2-ammonio propyl)amino]diazen-1-ium 1,2-diolate (PAPA-NONOate). These two NO donor molecules allowed proving the electrochemical detection of (i) directly injected exogenous NO phosphate buffer solution into the tumor (decomposed DEA-NONOate) and (ii) biomimetically induced endogeneous release of NO in the tumoral tissue, upon injection of PAPA-NONOate into the tumor. This approach could be applied to the in vivo study of candidate anticancer drugs acting on the NO pathways.
European Journal of Pharmaceutics and Biopharmaceutics, Feb 1, 2015
Non viral gene transfection has been mostly reached via cationic polymer and lipid, required for ... more Non viral gene transfection has been mostly reached via cationic polymer and lipid, required for DNA complexation and cell internalisation. However, cationic charges often induce cytotoxicity and limit the efficacy of the lipoplexes in vivo due to their fast elimination from the blood stream. Few years ago, we had developed noncationic lipid interacting with DNA via hydrogen bond interactions. To take advantage of both the internalisation efficacy of cationic complexes and the higher DNA release efficacy of non cationic lipids, we chose to mix both ionic and hydrogen bond interactions within one lipoplex. The idea behind this strategy would be to reduce the overall charge while maintaining a high level of transfection. Four mixed formulations of cationic lipid and thiourea lipid were prepared. We found that decreasing ionic interactions and increasing hydrogen bond interactions improved cationic lipoplexes properties. Indeed, we showed that replacement of net positive charges by hydrogen bond interactions with DNA phosphates led to efficient lipoplexes for in vitro DNA transfection at lower cationic charge content, which consequently reduced lipoplex cytotoxicity.
Persistent Luminescence Induced by Upconversion: An Alternative Approach for Rechargeable Bio‐Emitters
Advanced Optical Materials, Jan 18, 2023
The charging of persistent luminescence using an infrared laser as a power source and an upconver... more The charging of persistent luminescence using an infrared laser as a power source and an upconversion process is a recently proposed trend in the field of persistent luminescence that allows expansion of the potential applications for these materials. In bioimaging at nanoscale, it allows for increased rechargeability capacity, as the excitation wavelength is fully inside the biological window. In this work, a novel approach is proposed to this phenomenon using energy transfer on associated materials. For this purpose, β‐NaGd0.8Yb0.17Er0.03F4 nanoparticles, known for their efficient upconversion, and Zn1.33Ga1.335Sn0.33Cr0.005O4 nanoparticles, known for their persistent luminescence properties, have been synthesized and associated through a dry impregnation method. The obtained hybrid material is found to present persistent luminescence at 700 nm after charging with a 980 nm laser. A mechanism is proposed to explain this energy transfer process and the capabilities of the hybrid material as rechargeable persistent nanoprobe for in vivo applications are shown.
In Vivo Electrochemical Detection of Nitroglycerin-Derived Nitric Oxide in Tumor-Bearing Mice
Electroanalysis, Feb 1, 2009
The ability of an inserted electrode to detect in vivo NO in tumor was achieved by using a chemic... more The ability of an inserted electrode to detect in vivo NO in tumor was achieved by using a chemically modified Pt/Ir electrode as NO‐sensor and nitroglycerin NTG as NO donor. Enzymatically induced release of NO from NTG was tracked in the tumor, upon intra peritoneal injection of NTG. This approach allowed in vivo monitoring of the bioavailability of NO and could be applied to the in vivo study of candidate anticancer drugs acting on the NO pathways.
We have studied radiolabelled plasmid DNA biodistribution and degradation in the muscle at differ... more We have studied radiolabelled plasmid DNA biodistribution and degradation in the muscle at different times after injection, with or without electrotransfer using previously defined conditions. Radiolabelled plasmid progressively left the muscle and was degraded as soon as 5 min after plasmid injection, with or without electrotransfer. Autoradiography showed that the major part of injected radioactivity was detected in the interfibrilar
In vivo ultrasound modulated optical tomography with a persistent spectral hole burning filter
Biomedical Optics Express, Nov 16, 2022
We present in vivo ultrasound modulated optical tomography (UOT) results on mice, using the persi... more We present in vivo ultrasound modulated optical tomography (UOT) results on mice, using the persistent spectral hole burning (PSHB) effect in a Tm3+:YAG crystal. Indocyanine green (ICG) solution was injected as an optical absorber and was clearly identified on the PSHB-UOT images, both in the muscle (following an intramuscular injection) and in the liver (following an intravenous injection). This demonstration also validates an experimental setup with an improved level of performance combined with an increased technological maturity compared to previous demonstrations.
The inside cover picture shows the disruption of endothelial cell cords by a 4-azapodophyllotoxin... more The inside cover picture shows the disruption of endothelial cell cords by a 4-azapodophyllotoxin analogue at a subtoxic concentration (green arrow). This effect is rapidly reversible after drug washout (red arrow). This is the first example of a compound of this class acting as a vascular-disrupting agent. For more information, see the Full Paper by Sylviane Giorgi-Renault et al. on p. 2016 ff.
Combretastatin anlogues: synthesis and biological evaluation of new disubstituted analogues of 6-methoxy-3-(3',4',5'-trimethoxy-benzoyl)-1H-indole (BPR0L075), as potential antivascular agents
Optical imaging is a rapidly developing field of research aimed at noninvasive monitoring of dise... more Optical imaging is a rapidly developing field of research aimed at noninvasive monitoring of disease progression, evaluating the effects and pharmacokinetic of a drug, or identifying pathological biomarkers. To this end, it requires the development of targeting and highly specific contrast agents. In fluorescence imaging, an external light of appropriate wavelength is used to excite the fluorescent molecule, followed almost immediately by the release of longer wavelength, lower energy light for imaging. Fluorescence is increasingly used for imaging and has provided remarkable results. However this technique presents several limitations, especially due to tissue autofluorescence under external illumination and weak tissue penetration of low wavelength excitation light. To overcome these drawbacks, we have developed an innovative technique using persistent luminescence nanoparticles (PLNP) for optical imaging in small animal. Such nanoparticles can be excited before systemic injection, and their biodistribution monitored in real-time for dozen of minutes without the need for any external illumination source. This review article will focus on recent works undertaken in our laboratory on the synthesis of PLNP, their surface modifications and applications for bioimaging.
Scanning ElectroChemical Microscopy (SECM) has emerged as a very attractive method to image livin... more Scanning ElectroChemical Microscopy (SECM) has emerged as a very attractive method to image living cells activity due to its non invasive character and to the possibility of concomitant electro-and physicochemical measurements. One of the difficulties when studying morphology of living cells in real time by SECM, using classical constant height mode, is the low contrast of the obtained images due to the insulating character of both the cells and of the underlying substrates. We propose here a technical approach to improve the contrast of SECM imagery obtained at constant height in the feedback mode without the need of Faraday cage. To this aim, a piece of biocompatible transparent conductive substrate (indium tin oxide, ITO coated PET) was attached into the bottom of cell culture well over which the cells were cultured. The transparency of ITO is intended to perform simultaneously SECM and optical microscopy measurements. The concept was applied to the study of endothelial cells, EA.hy926, whose morphology may be altered via an antivascular treatment. Our results show that the differences in the conductivity of the substrate and of the cells enhance the contrast of SECM image in feedback mode at constant height using highly charged redox mediator. In addition, differences in cell morphology are significantly observed by SECM after cell treatment with Combretastatin A4 antivascular agent.
Nanoparticle technology in cancer chemotherapy is a promising approach to enhance active ingredie... more Nanoparticle technology in cancer chemotherapy is a promising approach to enhance active ingredient pharmacology and pharmacodynamics. Indeed, drug nanoparticles display various assets such as extended blood lifespan, high drug loading and reduced cytotoxicity leading to better drug compliance. In this context, organic nanocrystal suspensions for pharmaceutical use have been developed in the past ten years. Nanocrystals offer new possibilities by combining the nanoformulation features with the properties of solid dispersed therapeutic ingredients including (i) high loading of the active ingredient, (ii) its bioavailability improvement, and (iii) reduced drug systemic cytotoxicity. However, surprisingly, no antitumoral drug has been marketed as a nanocrystal suspension until now. Etoposide, which is largely used as an anti-cancerous agent against testicular, ovarian, small cell lung, colon and breast cancer in its liquid dosage form, has been selected to develop injectable nanocrystal suspensions designed to be transferred to the clinic. The aim of the present work is to provide optimized formulations for nanostructured etoposide solutions and validate by means of in vitro and in vivo evaluations the efficiency of this multiphase system. Indeed, the etoposide formulated as a nanosuspension by a bottom-up approach showed higher blood life span, reduced tumor growth and higher tolerance in a murine carcinoma cancer model. The results obtained are promising for future clinical evaluation of these etoposide nanosuspensions. Nanomedicines have paved the way to new opportunities for therapeutic treatments since biocompatible nanosize based particles may enhance the overall pharmacological properties of a given drug substance 1 , such as improved bioavailability and targeting 2 , extended release 3 , decreased side effects 4 , as well as expanding various administration routes 5. Since the last decade, parenteral nanocrystal (NC) suspensions of active pharmaceutical ingredients (APIs) have emerged for various therapies as it was published by our group as a review 1 year ago 6. As far as chemotherapy treatments are concerned, many researches lead to the proof of concept for NC preparation and stabilization (e.g. doxorubicin 7 , hesperetin 8,9 , hydroxycamptothecin 10,11 , oridonin 12 , paclitaxel 13-19 , puerarin 20 , riccardin 21 , silybin 20). However, until the present work, no antitumoral drug has been marketed as a NC preparation for i.v. administration for cancer treatments 6,22-24. In this study, etoposide (ETO) was prepared
Nanoparticles are now emerging as a novel class of autophagy activators. Functionalized single-wa... more Nanoparticles are now emerging as a novel class of autophagy activators. Functionalized single-walled carbon nanotubes (f-SWCNTs) are valuable nanomaterials in many industries. This article is designed to assess the autophagic response for f-SWCNTs exposure in vitro and in vivo. A few types of f-SWCNTs were screened in human lung adenocarcinoma A549 cells for the autophagic response and related pathways in vitro. Formation of autophagosomes and LC3-II upregulation were confirmed on the basis of electron microscopy and LC3 western blotting for COOH-CNT, but not for PABS-CNT and PEG-CNT. MTT assay showed marked increase in cell viability, when COOH-CNT was added to cells in the presence of autophagy inhibitor 3MA, ATG6 or TSC2 siRNA. Consistent with the involvement of the Akt-TSC1/2-mTOR pathway, the phosphorylation levels of mTOR, mTOR's substrate S6 and Akt were shown significantly decreased in A549 cells on treatment with COOH-CNT using western blotting. What's more, autophagy inhibitor 3MA significantly reduced the lung edema in vivo. In a word, COOH-CNT induced autophagic cell death in A549 cells through the AKT-TSC2-mTOR pathway and caused acute lung injury in vivo. Inhibition of autophagy significantly reduced COOH-CNT-induced autophagic cell death and ameliorated acute lung injury in mice, suggesting a potential remedy to address the growing concerns on the safety of nanomaterials.
Persistent luminescence (PersL) nanoparticles offer attractive capabilities for in vivo imaging a... more Persistent luminescence (PersL) nanoparticles offer attractive capabilities for in vivo imaging applications as an optical excitation of the nanoparticles outside the animal before injection is possible. Therefore, long-lasting emission of light allows performing in vivo imaging with high signal to noise ratio and with high sensitivity. Here we report the development of LaAlO 3 (LAO) nano-perovskite doped with Cr 3+ and Sm 3+ , the trivalent chromium cation being the recombination center, while Sm 3+ is used to enhance the persistent properties. Nanoparticles are synthesized by co-precipitation method and are tailored to present deep red persistent luminescence at 734 nm due to the Cr 3+ : 2 E(2 G) → 4 A 2 (4 F) transition after UV excitation. The intense deep red PersL matches well with the first biological window (650-950 nm). These nanoparticles have been successfully functionalized with polyethylene glycol (PEG) and the stealth obtained nanoparticles were tested for the first time for imaging on small animal in order to have access to their in vivo biodistribution.
A growing insight toward optical sensors has led to several major improvements in the development... more A growing insight toward optical sensors has led to several major improvements in the development of convenient probes for in vivo imaging. Efficient optical detection using quantum dots (QDs) as well as near-infrared organic dyes relies on several key driving principles: the ability to lower background absorption or autofluorescence from tissue, a good photostability of the probe, and a high quantum yield. In this article, we report the real-time biodistribution monitoring of lanthanide-doped persistent luminescence nanoparticles (PLNP), emitting in the near-infrared window, in healthy and tumor-bearing mice. We focused on the influence of hydrodynamic diameter, ranging from 80 to 180 nm, and polyethylene glycol (PEG) surface coating on the behavior of our probes. Tissue distribution was found to be highly dependent on surface coverage as well as core diameter. The amount of PLNP in the blood was highly increased for small (d < 80 nm) and stealth particles. On the opposite, PEG shield molecular weight, ranging from 5 to 20 kDa, had only negligible influence on the in vivo biodistribution of our silicate-based material.
Novel in situ gelling ophthalmic drug delivery system based on gellan gum and hydroxyethylcellulo... more Novel in situ gelling ophthalmic drug delivery system based on gellan gum and hydroxyethylcellulose: Innovative rheological characterization, in vitro and in vivo evidence of a sustained precorneal retention time,
-L'imagerie par bioluminescence est une technologie d'imagerie optique basée sur la détection de ... more -L'imagerie par bioluminescence est une technologie d'imagerie optique basée sur la détection de photons produits par une réaction biologique entre un substrat et une enzyme dans les tissus vivants. Cette technique d'imagerie, peu bruitée, est utilisée dans de nombreux domaines de la recherche biomédicale et notamment en oncologie préclinique. Le flux de photonsémis par une tumeur est liéà son volume et sonétat métabolique, nécessitant une localisation précise de celle-ci. Certaines expériences impliquent la visualisation de signaux multiples (par exemple 2 tumeurs) sur le même animal ce qui rend leur quantification difficile car la délimitation manuelle de la région d'intérêt (ROI) doit etre plus fine et est le plus souvent arbitraire. Dans ce travail, nousétudions l'utilisation de la décomposition factorielle par Factorisation Non-Négative de Matrice (Non-Negative Matrix Factorization, NMF) comme méthode de séparation des sources afin de permettre une quantification plus précise de chaque tumeur sans a priori spatial.
After excitation in the biological transparency window, chromium-doped zinc gallate nanoparticles... more After excitation in the biological transparency window, chromium-doped zinc gallate nanoparticles (ZGO NPs) emit near-infrared luminescence for more than an hour, allowing long-term imaging to be performed without background autofluorescence. However, these nanoparticles are recognized in just a few minutes by serum proteins and are then trapped in the liver. In this article, we put forth that liver uptake can be delayed when coating the surface of ZGO NPs with zwitterions. We focused on the use of a very small zwitterion molecule of 330 Da derived from sulfobetaine silane (SBS) and its grafting in one step and in water onto zinc gallate nanoparticles, and we compared the colloidal stability, the in vitro interactions with serum proteins, and the biodistribution in mice with PEGylated ZGO NPs (5000 Da) prepared in two steps in organic solvent. In vitro quantification of serum protein adsorption suggests that the similarity between the sulfobetaine and the cell membrane is enough to ...
In Vivo Electrochemical Detection of Nitric Oxide in Tumor-Bearing Mice
Analytical Chemistry, Dec 20, 2006
Interest in elucidating the mechanisms of action of various classes of anticancer agents and expl... more Interest in elucidating the mechanisms of action of various classes of anticancer agents and exploring the pathways of the induced-nitric oxide (NO) release provides an impetus to conceive a better designed approach to locally detect NO in tumors, in vivo. We report here on the first use of an electrochemical sensor that allows the in vivo detection of NO in tumor-bearing mice. In a first step, we performed the electrochemical characterization of a stable electroactive probe, K4Fe(CN)6, directly injected into the liquid microenvironment especially created around the electrode in the tumor. Second, the ability of the inserted electrode system to detect the presence of NO itself in the tumoral tissue was achieved by using the chemically modified Pt/Ir electrode as NO sensor and two NO donor molecules: diethylammonium (Z)-1-(N,N-diethylamino)diazen-1-ium 1,2-diolate (DEA-NONOate) and (Z)-1-[N-(2-aminopropyl)-N-(2-ammonio propyl)amino]diazen-1-ium 1,2-diolate (PAPA-NONOate). These two NO donor molecules allowed proving the electrochemical detection of (i) directly injected exogenous NO phosphate buffer solution into the tumor (decomposed DEA-NONOate) and (ii) biomimetically induced endogeneous release of NO in the tumoral tissue, upon injection of PAPA-NONOate into the tumor. This approach could be applied to the in vivo study of candidate anticancer drugs acting on the NO pathways.
European Journal of Pharmaceutics and Biopharmaceutics, Feb 1, 2015
Non viral gene transfection has been mostly reached via cationic polymer and lipid, required for ... more Non viral gene transfection has been mostly reached via cationic polymer and lipid, required for DNA complexation and cell internalisation. However, cationic charges often induce cytotoxicity and limit the efficacy of the lipoplexes in vivo due to their fast elimination from the blood stream. Few years ago, we had developed noncationic lipid interacting with DNA via hydrogen bond interactions. To take advantage of both the internalisation efficacy of cationic complexes and the higher DNA release efficacy of non cationic lipids, we chose to mix both ionic and hydrogen bond interactions within one lipoplex. The idea behind this strategy would be to reduce the overall charge while maintaining a high level of transfection. Four mixed formulations of cationic lipid and thiourea lipid were prepared. We found that decreasing ionic interactions and increasing hydrogen bond interactions improved cationic lipoplexes properties. Indeed, we showed that replacement of net positive charges by hydrogen bond interactions with DNA phosphates led to efficient lipoplexes for in vitro DNA transfection at lower cationic charge content, which consequently reduced lipoplex cytotoxicity.
Persistent Luminescence Induced by Upconversion: An Alternative Approach for Rechargeable Bio‐Emitters
Advanced Optical Materials, Jan 18, 2023
The charging of persistent luminescence using an infrared laser as a power source and an upconver... more The charging of persistent luminescence using an infrared laser as a power source and an upconversion process is a recently proposed trend in the field of persistent luminescence that allows expansion of the potential applications for these materials. In bioimaging at nanoscale, it allows for increased rechargeability capacity, as the excitation wavelength is fully inside the biological window. In this work, a novel approach is proposed to this phenomenon using energy transfer on associated materials. For this purpose, β‐NaGd0.8Yb0.17Er0.03F4 nanoparticles, known for their efficient upconversion, and Zn1.33Ga1.335Sn0.33Cr0.005O4 nanoparticles, known for their persistent luminescence properties, have been synthesized and associated through a dry impregnation method. The obtained hybrid material is found to present persistent luminescence at 700 nm after charging with a 980 nm laser. A mechanism is proposed to explain this energy transfer process and the capabilities of the hybrid material as rechargeable persistent nanoprobe for in vivo applications are shown.
In Vivo Electrochemical Detection of Nitroglycerin-Derived Nitric Oxide in Tumor-Bearing Mice
Electroanalysis, Feb 1, 2009
The ability of an inserted electrode to detect in vivo NO in tumor was achieved by using a chemic... more The ability of an inserted electrode to detect in vivo NO in tumor was achieved by using a chemically modified Pt/Ir electrode as NO‐sensor and nitroglycerin NTG as NO donor. Enzymatically induced release of NO from NTG was tracked in the tumor, upon intra peritoneal injection of NTG. This approach allowed in vivo monitoring of the bioavailability of NO and could be applied to the in vivo study of candidate anticancer drugs acting on the NO pathways.
We have studied radiolabelled plasmid DNA biodistribution and degradation in the muscle at differ... more We have studied radiolabelled plasmid DNA biodistribution and degradation in the muscle at different times after injection, with or without electrotransfer using previously defined conditions. Radiolabelled plasmid progressively left the muscle and was degraded as soon as 5 min after plasmid injection, with or without electrotransfer. Autoradiography showed that the major part of injected radioactivity was detected in the interfibrilar
In vivo ultrasound modulated optical tomography with a persistent spectral hole burning filter
Biomedical Optics Express, Nov 16, 2022
We present in vivo ultrasound modulated optical tomography (UOT) results on mice, using the persi... more We present in vivo ultrasound modulated optical tomography (UOT) results on mice, using the persistent spectral hole burning (PSHB) effect in a Tm3+:YAG crystal. Indocyanine green (ICG) solution was injected as an optical absorber and was clearly identified on the PSHB-UOT images, both in the muscle (following an intramuscular injection) and in the liver (following an intravenous injection). This demonstration also validates an experimental setup with an improved level of performance combined with an increased technological maturity compared to previous demonstrations.
The inside cover picture shows the disruption of endothelial cell cords by a 4-azapodophyllotoxin... more The inside cover picture shows the disruption of endothelial cell cords by a 4-azapodophyllotoxin analogue at a subtoxic concentration (green arrow). This effect is rapidly reversible after drug washout (red arrow). This is the first example of a compound of this class acting as a vascular-disrupting agent. For more information, see the Full Paper by Sylviane Giorgi-Renault et al. on p. 2016 ff.
Combretastatin anlogues: synthesis and biological evaluation of new disubstituted analogues of 6-methoxy-3-(3',4',5'-trimethoxy-benzoyl)-1H-indole (BPR0L075), as potential antivascular agents
Optical imaging is a rapidly developing field of research aimed at noninvasive monitoring of dise... more Optical imaging is a rapidly developing field of research aimed at noninvasive monitoring of disease progression, evaluating the effects and pharmacokinetic of a drug, or identifying pathological biomarkers. To this end, it requires the development of targeting and highly specific contrast agents. In fluorescence imaging, an external light of appropriate wavelength is used to excite the fluorescent molecule, followed almost immediately by the release of longer wavelength, lower energy light for imaging. Fluorescence is increasingly used for imaging and has provided remarkable results. However this technique presents several limitations, especially due to tissue autofluorescence under external illumination and weak tissue penetration of low wavelength excitation light. To overcome these drawbacks, we have developed an innovative technique using persistent luminescence nanoparticles (PLNP) for optical imaging in small animal. Such nanoparticles can be excited before systemic injection, and their biodistribution monitored in real-time for dozen of minutes without the need for any external illumination source. This review article will focus on recent works undertaken in our laboratory on the synthesis of PLNP, their surface modifications and applications for bioimaging.
Scanning ElectroChemical Microscopy (SECM) has emerged as a very attractive method to image livin... more Scanning ElectroChemical Microscopy (SECM) has emerged as a very attractive method to image living cells activity due to its non invasive character and to the possibility of concomitant electro-and physicochemical measurements. One of the difficulties when studying morphology of living cells in real time by SECM, using classical constant height mode, is the low contrast of the obtained images due to the insulating character of both the cells and of the underlying substrates. We propose here a technical approach to improve the contrast of SECM imagery obtained at constant height in the feedback mode without the need of Faraday cage. To this aim, a piece of biocompatible transparent conductive substrate (indium tin oxide, ITO coated PET) was attached into the bottom of cell culture well over which the cells were cultured. The transparency of ITO is intended to perform simultaneously SECM and optical microscopy measurements. The concept was applied to the study of endothelial cells, EA.hy926, whose morphology may be altered via an antivascular treatment. Our results show that the differences in the conductivity of the substrate and of the cells enhance the contrast of SECM image in feedback mode at constant height using highly charged redox mediator. In addition, differences in cell morphology are significantly observed by SECM after cell treatment with Combretastatin A4 antivascular agent.
Nanoparticle technology in cancer chemotherapy is a promising approach to enhance active ingredie... more Nanoparticle technology in cancer chemotherapy is a promising approach to enhance active ingredient pharmacology and pharmacodynamics. Indeed, drug nanoparticles display various assets such as extended blood lifespan, high drug loading and reduced cytotoxicity leading to better drug compliance. In this context, organic nanocrystal suspensions for pharmaceutical use have been developed in the past ten years. Nanocrystals offer new possibilities by combining the nanoformulation features with the properties of solid dispersed therapeutic ingredients including (i) high loading of the active ingredient, (ii) its bioavailability improvement, and (iii) reduced drug systemic cytotoxicity. However, surprisingly, no antitumoral drug has been marketed as a nanocrystal suspension until now. Etoposide, which is largely used as an anti-cancerous agent against testicular, ovarian, small cell lung, colon and breast cancer in its liquid dosage form, has been selected to develop injectable nanocrystal suspensions designed to be transferred to the clinic. The aim of the present work is to provide optimized formulations for nanostructured etoposide solutions and validate by means of in vitro and in vivo evaluations the efficiency of this multiphase system. Indeed, the etoposide formulated as a nanosuspension by a bottom-up approach showed higher blood life span, reduced tumor growth and higher tolerance in a murine carcinoma cancer model. The results obtained are promising for future clinical evaluation of these etoposide nanosuspensions. Nanomedicines have paved the way to new opportunities for therapeutic treatments since biocompatible nanosize based particles may enhance the overall pharmacological properties of a given drug substance 1 , such as improved bioavailability and targeting 2 , extended release 3 , decreased side effects 4 , as well as expanding various administration routes 5. Since the last decade, parenteral nanocrystal (NC) suspensions of active pharmaceutical ingredients (APIs) have emerged for various therapies as it was published by our group as a review 1 year ago 6. As far as chemotherapy treatments are concerned, many researches lead to the proof of concept for NC preparation and stabilization (e.g. doxorubicin 7 , hesperetin 8,9 , hydroxycamptothecin 10,11 , oridonin 12 , paclitaxel 13-19 , puerarin 20 , riccardin 21 , silybin 20). However, until the present work, no antitumoral drug has been marketed as a NC preparation for i.v. administration for cancer treatments 6,22-24. In this study, etoposide (ETO) was prepared
Nanoparticles are now emerging as a novel class of autophagy activators. Functionalized single-wa... more Nanoparticles are now emerging as a novel class of autophagy activators. Functionalized single-walled carbon nanotubes (f-SWCNTs) are valuable nanomaterials in many industries. This article is designed to assess the autophagic response for f-SWCNTs exposure in vitro and in vivo. A few types of f-SWCNTs were screened in human lung adenocarcinoma A549 cells for the autophagic response and related pathways in vitro. Formation of autophagosomes and LC3-II upregulation were confirmed on the basis of electron microscopy and LC3 western blotting for COOH-CNT, but not for PABS-CNT and PEG-CNT. MTT assay showed marked increase in cell viability, when COOH-CNT was added to cells in the presence of autophagy inhibitor 3MA, ATG6 or TSC2 siRNA. Consistent with the involvement of the Akt-TSC1/2-mTOR pathway, the phosphorylation levels of mTOR, mTOR's substrate S6 and Akt were shown significantly decreased in A549 cells on treatment with COOH-CNT using western blotting. What's more, autophagy inhibitor 3MA significantly reduced the lung edema in vivo. In a word, COOH-CNT induced autophagic cell death in A549 cells through the AKT-TSC2-mTOR pathway and caused acute lung injury in vivo. Inhibition of autophagy significantly reduced COOH-CNT-induced autophagic cell death and ameliorated acute lung injury in mice, suggesting a potential remedy to address the growing concerns on the safety of nanomaterials.
Persistent luminescence (PersL) nanoparticles offer attractive capabilities for in vivo imaging a... more Persistent luminescence (PersL) nanoparticles offer attractive capabilities for in vivo imaging applications as an optical excitation of the nanoparticles outside the animal before injection is possible. Therefore, long-lasting emission of light allows performing in vivo imaging with high signal to noise ratio and with high sensitivity. Here we report the development of LaAlO 3 (LAO) nano-perovskite doped with Cr 3+ and Sm 3+ , the trivalent chromium cation being the recombination center, while Sm 3+ is used to enhance the persistent properties. Nanoparticles are synthesized by co-precipitation method and are tailored to present deep red persistent luminescence at 734 nm due to the Cr 3+ : 2 E(2 G) → 4 A 2 (4 F) transition after UV excitation. The intense deep red PersL matches well with the first biological window (650-950 nm). These nanoparticles have been successfully functionalized with polyethylene glycol (PEG) and the stealth obtained nanoparticles were tested for the first time for imaging on small animal in order to have access to their in vivo biodistribution.
A growing insight toward optical sensors has led to several major improvements in the development... more A growing insight toward optical sensors has led to several major improvements in the development of convenient probes for in vivo imaging. Efficient optical detection using quantum dots (QDs) as well as near-infrared organic dyes relies on several key driving principles: the ability to lower background absorption or autofluorescence from tissue, a good photostability of the probe, and a high quantum yield. In this article, we report the real-time biodistribution monitoring of lanthanide-doped persistent luminescence nanoparticles (PLNP), emitting in the near-infrared window, in healthy and tumor-bearing mice. We focused on the influence of hydrodynamic diameter, ranging from 80 to 180 nm, and polyethylene glycol (PEG) surface coating on the behavior of our probes. Tissue distribution was found to be highly dependent on surface coverage as well as core diameter. The amount of PLNP in the blood was highly increased for small (d < 80 nm) and stealth particles. On the opposite, PEG shield molecular weight, ranging from 5 to 20 kDa, had only negligible influence on the in vivo biodistribution of our silicate-based material.
Novel in situ gelling ophthalmic drug delivery system based on gellan gum and hydroxyethylcellulo... more Novel in situ gelling ophthalmic drug delivery system based on gellan gum and hydroxyethylcellulose: Innovative rheological characterization, in vitro and in vivo evidence of a sustained precorneal retention time,
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Papers by Johanne Seguin