Antonio Nunes - Academia.edu (original) (raw)
Papers by Antonio Nunes
Biomedicines, 2021
Breast cancer is a complex tumor type involving many biological processes. Most chemotherapeutic ... more Breast cancer is a complex tumor type involving many biological processes. Most chemotherapeutic agents exert their antitumoral effects by rapid induction of apoptosis. Another main feature of breast cancer is hypoxia, which may drive malignant progression and confer resistance to various forms of therapy. Thus, multi-aspect imaging of both tumor apoptosis and oxygenation in vivo would be of enormous value for the effective evaluation of therapy response. Herein, we demonstrate the capability of a hybrid imaging modality known as multispectral optoacoustic tomography (MSOT) to provide high-resolution, simultaneous imaging of tumor apoptosis and oxygenation, based on both the exogenous contrast of an apoptosis-targeting dye and the endogenous contrast of hemoglobin. MSOT imaging was applied on mice bearing orthotopic 4T1 breast tumors before and following treatment with doxorubicin. Apoptosis was monitored over time by imaging the distribution of xPLORE-APOFL750©, a highly sensitive ...
Biomaterials, 2015
Multispectral optoacoustic tomography (MSOT) is a powerful modality that allows high-resolution i... more Multispectral optoacoustic tomography (MSOT) is a powerful modality that allows high-resolution imaging of photo-absorbers deep within tissue, beyond the classical depth and resolution limitations of conventional optical imaging. Imaging of intrinsic tissue contrast can be complemented by extrinsically administered gold nanoparticles or fluorescent molecular probes. Instead, we investigated herein generation of re-engineered clinically-used PEGylated liposomes incorporating indocyanine green (LipoICG) as a contrast strategy that combines materials already approved for clinical use, with strong photoabsorbing signal generation available today only from some metallic nanoparticles (e.g. gold nanorods). Using MSOT we confirmed LipoICG as a highly potent optoacoustic agent and resolved tissue accumulation in tumor-bearing animals over time with high-sensitivity and resolution using two tumor models of different vascularisation. We further showcase a paradigm shift in pharmacology studies and nanoparticle investigation, by enabling detailed volumetric optical imaging in vivo through the entire tumor tissue non-invasively, elucidating never before seen spatiotemporal features of optical agent distribution. These results point to LipoICG as a particle with significant advantageous characteristics over gold nanoparticles and organic dyes.
Therapeutic applications of gene silencing using siRNA have seen increasing interest over the pas... more Therapeutic applications of gene silencing using siRNA have seen increasing interest over the past decade. The optimization of the delivery and biodistribution of siRNA using liposome-gold nanorod (AuNRs) nanoscale carriers can greatly benefit from adept imaging methods that can visualize the time-resolved delivery performance of such vectors. In this work, we describe the effect of AuNR length incorporated with liposomes and show their complexation with siRNA as a novel gene delivery vehicle. We demonstrate the application of multispectral optoacoustic tomography (MSOT) to longitudinally visualize the localisation of siRNA carrying liposome-AuNR hybrids within tumors. Combination of in vivo MSOT with ex vivo fluorescence cryo-slice imaging offers further insight into the siRNA transport and activity obtained. † Electronic supplementary information (ESI) available: Experimental section and dark-field microscopy in both tumors 24 h after injection of the complex have been included. See
FASEB journal : official publication of the Federation of American Societies for Experimental Biology, 2010
One of the major obstacles to the clinical development of gene silencing by small interfering RNA... more One of the major obstacles to the clinical development of gene silencing by small interfering RNA (siRNA) is its effective cytoplasmic delivery. Carbon nanotubes have been proposed as novel nanomaterials that can offer significant advantages for the intracellular delivery of nucleic acids, such as siRNA. We recently demonstrated in a proof-of-principle study that amino-functionalized multiwalled carbon nanotubes (f-MWNT) can effectively deliver in vivo an siRNA sequence, triggering cell apoptosis that results in human lung xenograft eradication and prolonged survival. In the present study, we demonstrate how a newly synthesized series of polycationic dendron-MWNT constructs with a precisely tailored number of amino functions (dendron generations) can complex and effectively deliver double-stranded siRNA to achieve gene silencing in vitro. A systematic comparison between the f-MWNT series in terms of cellular uptake, cytotoxicity, and siRNA complexation is offered. Significant improv...
Neoplasia (New York, N.Y.), 2016
Diversity of the design and alignment of illumination and ultrasonic transducers empower the fine... more Diversity of the design and alignment of illumination and ultrasonic transducers empower the fine scalability and versatility of optoacoustic imaging. In this study, we implement an innovative high-resolution optoacoustic mesoscopy for imaging the vasculature and tissue oxygenation within subcutaneous and orthotopic cancerous implants of mice in vivo through acquisition of tomographic projections over 180° at a central frequency of 24 MHz. High-resolution volumetric imaging was combined with multispectral functional measurements to resolve the exquisite inner structure and vascularization of the entire tumor mass using endogenous and exogenous optoacoustic contrast. Evidence is presented for constitutive hypoxemia within the carcinogenic tissue through analysis of the hemoglobin absorption spectra and distribution. Morphometric readouts obtained with optoacoustic mesoscopy have been verified with high-resolution ultramicroscopic studies. The findings described herein greatly extend ...
International journal of nanomedicine, 2016
In this work, we report that the biodistribution and excretion of carbon nanohorns (CNHs) in mice... more In this work, we report that the biodistribution and excretion of carbon nanohorns (CNHs) in mice are dependent on their size and functionalization. Small-sized CNHs (30-50 nm; S-CNHs) and large-sized CNHs (80-100 nm; L-CNHs) were chemically functionalized and radiolabeled with [(111)In]-diethylenetriaminepentaacetic acid and intravenously injected into mice. Their tissue distribution profiles at different time points were determined by single photon emission computed tomography/computed tomography. The results showed that the S-CNHs circulated longer in blood, while the L-CNHs accumulated faster in major organs like the liver and spleen. Small amounts of S-CNHs- and L-CNHs were excreted in urine within the first few hours postinjection, followed by excretion of smaller quantities within the next 48 hours in both urine and feces. The kinetics of excretion for S-CNHs were more rapid than for L-CNHs. Both S-CNH and L-CNH material accumulated mainly in the liver and spleen; however, S-...
Nature Communications, 2016
Medical Physics, 2015
Purpose: With recent advancement in hardware of optoacoustic imaging systems, highly detailed cro... more Purpose: With recent advancement in hardware of optoacoustic imaging systems, highly detailed cross-sectional images may be acquired at a single laser shot, thus eliminating motion artifacts. Nonetheless, other sources of artifacts remain due to signal distortion or out-of-plane signals. The purpose of image reconstruction algorithms is to obtain the most accurate images from noisy, distorted projection data. Methods: In this paper, the authors use the model-based approach for acoustic inversion, combined with a sparsity-based inversion procedure. Specifically, a cost function is used that includes the L1 norm of the image in sparse representation and a total variation (TV) term. The optimization problem is solved by a numerically efficient implementation of a nonlinear gradient descent algorithm. TV-L1 model-based inversion is tested in the cross section geometry for numerically generated data as well as for in vivo experimental data from an adult mouse. Results: In all cases, model-based TV-L1 inversion showed a better performance over the conventional Tikhonov regularization, TV inversion, and L1 inversion. In the numerical examples, the images reconstructed with TV-L1 inversion were quantitatively more similar to the originating images. In the experimental examples, TV-L1 inversion yielded sharper images and weaker streak artifact. Conclusions: The results herein show that TV-L1 inversion is capable of improving the quality of highly detailed, multiscale optoacoustic images obtained in vivo using cross-sectional imaging systems. As a result of its high fidelity, model-based TV-L1 inversion may be considered as the new standard for image reconstruction in cross-sectional imaging.
Optics letters, Jan 15, 2014
Multispectral optoacoustic tomography (MSOT) offers the potential to image in high-resolution cel... more Multispectral optoacoustic tomography (MSOT) offers the potential to image in high-resolution cells tagged with optical labels. In contrast to single wavelength imaging, multispectral excitation and spectral unmixing can differentiate labeled moieties over tissue absorption in the absence of background measurements. This feature can enable longitudinal cellular biology studies well beyond the depths reached by optical microscopy. However, the relation between spectrally resolved fluorescently labeled cells and optoacoustic detection has not been systematically investigated. Herein, we measured titrations of fluorescently labeled cells and establish the optoacoustic signal generated by these cells as a function of cell number and across different cell types. We then assess the MSOT sensitivity to resolve cells implanted in animals.
Journal of biophotonics, Jan 3, 2014
Molecular optoacoustic (photoacoustic) imaging typically relies on the spectral identification of... more Molecular optoacoustic (photoacoustic) imaging typically relies on the spectral identification of absorption signatures from molecules of interest. To achieve this, two or more excitation wavelengths are employed to sequentially illuminate tissue. Due to depth-related spectral dependencies and detection related effects, the multispectral optoacoustic tomography (MSOT) spectral unmixing problem presents a complex non-linear inversion operation. So far, different studies have showcased the spectral capacity of optoacoustic imaging, without however relating the performance achieved to the number of wavelengths employed. Overall, the dependence of the sensitivity and accuracy of optoacoustic imaging as a function of the number of illumination wavelengths has not been so far comprehensively studied. In this paper we study the impact of the number of excitation wavelengths employed on the sensitivity and accuracy achieved by molecular optoacoustic tomography. We present a quantitative ana...
Small, 2010
Carbon nanotubes (CNTs) consist of carbon atoms arranged in sheets of graphene rolled up into cyl... more Carbon nanotubes (CNTs) consist of carbon atoms arranged in sheets of graphene rolled up into cylindrical shapes. This class of nanomaterials has attracted attention because of their extraordinary properties, such as high electrical and thermal conductivity. In addition, development in CNT functionalization chemistry has led to an enhanced dispersibility in aqueous physiological media which indeed broadens the spectrum for their potential biological applications including gene delivery. The aim of this study is to determine the capability of different cationic polymergrafted multiwalled carbon nanotubes (MWNTs) (polymer-g-MWNTs) to effi ciently complex and transfer plasmid DNA (pCMVβ Gal) in vitro without promoting cytotoxicity. Carboxylated MWNT is chemically conjugated to the cationic polymers polyethylenimine (PEI), polyallylamine (PAA), or a mixture of the two polymers. In order to explore the potential of these polymer-g-MWNTs as gene delivery systems, we fi rst study their capacity to complex plasmid DNA (pDNA) using agarose gel electrophoresis. Gel migration studies confi rm pDNA binding to polymer-g-MWNT with different affi nities, highest for PEI-g-MWNT and PEI/PAA-g-CNT constructs. β-galactosidase expression is assessed in human lung epithelial (A549) cells, and the cytotoxicity is determined by modifi ed LDH assay after 24 h incubation period. Additionally, PEI-g-MWNT and/or PEI/PAA-g-MWNT reveal an improvement in gene expression when compared to the naked pDNA or to the equivalent amounts of PEI polymer alone. Mechanistically, pDNA was delivered by the polymerg-MWNT constructs via a different pathway compared to those used by polyplexes. In conclusion, polymer-g-MWNTs may be considered in the future as a versatile tool for effi cient gene transfer in cancer cells in vitro, provided their toxicological profi le is established. Nanomedicine A. Nunes et al.
PLoS ONE, 2013
The potential use of functionalized carbon nanotubes (f-CNTs) for drug and gene delivery to the c... more The potential use of functionalized carbon nanotubes (f-CNTs) for drug and gene delivery to the central nervous system (CNS) and as neural substrates makes the understanding of their in vivo interactions with the neural tissue essential. The aim of this study was to investigate the interactions between chemically functionalized multi-walled carbon nanotubes (f-MWNTs) and the neural tissue following cortical stereotactic administration. Two different f-MWNT constructs were used in these studies: shortened (by oxidation) amino-functionalized MWNT (oxMWNT-NH 3 +) and amino-functionalized MWNT (MWNT-NH 3 +). Parenchymal distribution of the stereotactically injected f-MWNTs was assessed by histological examination. Both f-MWNT were uptaken by different types of neural tissue cells (microglia, astrocytes and neurons), however different patterns of cellular internalization were observed between the nanotubes. Furthermore, immunohistochemical staining for specific markers of glial cell activation (GFAP and CD11b) was performed and secretion of inflammatory cytokines was investigated using real-time PCR (qRT-PCR). Injections of both f-MWNT constructs led to a local and transient induction of inflammatory cytokines at early time points. Oxidation of nanotubes seemed to induce significant levels of GFAP and CD11b over-expression in areas peripheral to the f-MWNT injection site. These results highlight the importance of nanotube functionalization on their interaction with brain tissue that is deemed critical for the development nanotube-based vector systems for CNS applications.
Nanomedicine, 2012
Aim: Carbon nanotubes (CNTs) are increasingly being utilized in neurological applications as comp... more Aim: Carbon nanotubes (CNTs) are increasingly being utilized in neurological applications as components of implants, electrodes or as delivery vehicles. Any application that involves implantation or injection of CNTs into the CNS needs to address the distribution and fate of the material following interaction and residence within the neuronal tissue. Here we report a preliminary study investigating the fate and structural integrity of amino-functionalized CNTs following stereotactic administration in the brain cortex. Materials & methods: The CNTs investigated had previously shown the capacity to internalize in various cell types of the CNS. An aqueous suspension of multiwalled CNT-NH3 + was stereotactically injected into the mouse brain cortex. Their interaction with neural cells and consequent effects on the CNT structural integrity was investigated by optical, transmission electron microscopy and Raman spectroscopy of brain tissue sections for a period between 2 and 14 days post ...
Proceedings of the National Academy of Sciences of the United States of America, Jan 5, 2011
Stroke is the second cause of death worldwide with ischemic stroke accounting for 80% of all stro... more Stroke is the second cause of death worldwide with ischemic stroke accounting for 80% of all stroke insults. Caspase-3 activation contributes to brain tissue loss and downstream biochemical events that lead to programmed cell death after traumatic brain injury. Alleviation of symptoms following ischemic neuronal injury can be potentially achieved by either genetic disruption or pharmacological inhibition of caspases. Here, we studied whether silencing of Caspase-3 using carbon nanotube-mediated in vivo RNA interference (RNAi) could offer a therapeutic opportunity against stroke. Effective delivery of siRNA directly to the CNS has been shown to normalize phenotypes in animal models of several neurological diseases. It is shown here that peri-lesional stereotactic administration of a Caspase-3 siRNA (siCas 3) delivered by functionalized carbon nanotubes (f-CNT) reduced neurodegeneration and promoted functional preservation before and after focal ischemic damage of the rodent motor cor...
Journal of Materials Chemistry, 2011
In this work we have synthesized a new series of cationic carbon nanotubes (CNTs) for siRNA bindi... more In this work we have synthesized a new series of cationic carbon nanotubes (CNTs) for siRNA binding. Both single-and multi-walled CNTs have been modified by addition or amidation reaction with short linear polyamine chains including putrescine, spermidine and spermine. All the new conjugates have been characterized with several spectroscopic and microscopic techniques. Their cytotoxic effects have been assessed on human lung carcinoma cell line. Finally, we have analyzed their capacity to bind siRNA towards the development of new carriers for gene silencing applications. The dispersibility properties and the capacity to complex siRNA of the different conjugates were found to be strongly dependent on the position of the functional groups on CNTs (i.e. mainly at the tips following the amidation reaction or on the sidewalls by direct CC addition).
Journal of Controlled Release, 2012
Treatment and diagnosis of neurodegenerative diseases and other CNS disorders are nowadays consid... more Treatment and diagnosis of neurodegenerative diseases and other CNS disorders are nowadays considered some of the most challenging tasks in modern medicine. The development of effective strategies for the prevention, diagnosis and treatment of CNS pathologies require better understanding of neurological disorders that is still lacking. The use of nanomaterials is thought to contribute to our further understanding of the CNS and the development of novel therapeutic and diagnostic modalities for neurological interventions. Even though the application of nanoparticles in neuroscience is still embryonic, this article attempts to illustrate the use of different types of nanomaterials and the way in which they have been used in various CNS applications in an attempt to limit or reverse neuropathological processes.
Chemical Communications, 2010
We have covalently grafted aptamers onto carboxylated carbon nanotubes to design a novel vector s... more We have covalently grafted aptamers onto carboxylated carbon nanotubes to design a novel vector system that can easily translocate into the cytosol of different cell types independent of receptor-mediated uptake. We propose the use of carbon nanotubes for the efficient intracellular delivery of biologically active aptamers for potential therapeutic applications.
Archives of Toxicology, 2012
Biomedicines, 2021
Breast cancer is a complex tumor type involving many biological processes. Most chemotherapeutic ... more Breast cancer is a complex tumor type involving many biological processes. Most chemotherapeutic agents exert their antitumoral effects by rapid induction of apoptosis. Another main feature of breast cancer is hypoxia, which may drive malignant progression and confer resistance to various forms of therapy. Thus, multi-aspect imaging of both tumor apoptosis and oxygenation in vivo would be of enormous value for the effective evaluation of therapy response. Herein, we demonstrate the capability of a hybrid imaging modality known as multispectral optoacoustic tomography (MSOT) to provide high-resolution, simultaneous imaging of tumor apoptosis and oxygenation, based on both the exogenous contrast of an apoptosis-targeting dye and the endogenous contrast of hemoglobin. MSOT imaging was applied on mice bearing orthotopic 4T1 breast tumors before and following treatment with doxorubicin. Apoptosis was monitored over time by imaging the distribution of xPLORE-APOFL750©, a highly sensitive ...
Biomaterials, 2015
Multispectral optoacoustic tomography (MSOT) is a powerful modality that allows high-resolution i... more Multispectral optoacoustic tomography (MSOT) is a powerful modality that allows high-resolution imaging of photo-absorbers deep within tissue, beyond the classical depth and resolution limitations of conventional optical imaging. Imaging of intrinsic tissue contrast can be complemented by extrinsically administered gold nanoparticles or fluorescent molecular probes. Instead, we investigated herein generation of re-engineered clinically-used PEGylated liposomes incorporating indocyanine green (LipoICG) as a contrast strategy that combines materials already approved for clinical use, with strong photoabsorbing signal generation available today only from some metallic nanoparticles (e.g. gold nanorods). Using MSOT we confirmed LipoICG as a highly potent optoacoustic agent and resolved tissue accumulation in tumor-bearing animals over time with high-sensitivity and resolution using two tumor models of different vascularisation. We further showcase a paradigm shift in pharmacology studies and nanoparticle investigation, by enabling detailed volumetric optical imaging in vivo through the entire tumor tissue non-invasively, elucidating never before seen spatiotemporal features of optical agent distribution. These results point to LipoICG as a particle with significant advantageous characteristics over gold nanoparticles and organic dyes.
Therapeutic applications of gene silencing using siRNA have seen increasing interest over the pas... more Therapeutic applications of gene silencing using siRNA have seen increasing interest over the past decade. The optimization of the delivery and biodistribution of siRNA using liposome-gold nanorod (AuNRs) nanoscale carriers can greatly benefit from adept imaging methods that can visualize the time-resolved delivery performance of such vectors. In this work, we describe the effect of AuNR length incorporated with liposomes and show their complexation with siRNA as a novel gene delivery vehicle. We demonstrate the application of multispectral optoacoustic tomography (MSOT) to longitudinally visualize the localisation of siRNA carrying liposome-AuNR hybrids within tumors. Combination of in vivo MSOT with ex vivo fluorescence cryo-slice imaging offers further insight into the siRNA transport and activity obtained. † Electronic supplementary information (ESI) available: Experimental section and dark-field microscopy in both tumors 24 h after injection of the complex have been included. See
FASEB journal : official publication of the Federation of American Societies for Experimental Biology, 2010
One of the major obstacles to the clinical development of gene silencing by small interfering RNA... more One of the major obstacles to the clinical development of gene silencing by small interfering RNA (siRNA) is its effective cytoplasmic delivery. Carbon nanotubes have been proposed as novel nanomaterials that can offer significant advantages for the intracellular delivery of nucleic acids, such as siRNA. We recently demonstrated in a proof-of-principle study that amino-functionalized multiwalled carbon nanotubes (f-MWNT) can effectively deliver in vivo an siRNA sequence, triggering cell apoptosis that results in human lung xenograft eradication and prolonged survival. In the present study, we demonstrate how a newly synthesized series of polycationic dendron-MWNT constructs with a precisely tailored number of amino functions (dendron generations) can complex and effectively deliver double-stranded siRNA to achieve gene silencing in vitro. A systematic comparison between the f-MWNT series in terms of cellular uptake, cytotoxicity, and siRNA complexation is offered. Significant improv...
Neoplasia (New York, N.Y.), 2016
Diversity of the design and alignment of illumination and ultrasonic transducers empower the fine... more Diversity of the design and alignment of illumination and ultrasonic transducers empower the fine scalability and versatility of optoacoustic imaging. In this study, we implement an innovative high-resolution optoacoustic mesoscopy for imaging the vasculature and tissue oxygenation within subcutaneous and orthotopic cancerous implants of mice in vivo through acquisition of tomographic projections over 180° at a central frequency of 24 MHz. High-resolution volumetric imaging was combined with multispectral functional measurements to resolve the exquisite inner structure and vascularization of the entire tumor mass using endogenous and exogenous optoacoustic contrast. Evidence is presented for constitutive hypoxemia within the carcinogenic tissue through analysis of the hemoglobin absorption spectra and distribution. Morphometric readouts obtained with optoacoustic mesoscopy have been verified with high-resolution ultramicroscopic studies. The findings described herein greatly extend ...
International journal of nanomedicine, 2016
In this work, we report that the biodistribution and excretion of carbon nanohorns (CNHs) in mice... more In this work, we report that the biodistribution and excretion of carbon nanohorns (CNHs) in mice are dependent on their size and functionalization. Small-sized CNHs (30-50 nm; S-CNHs) and large-sized CNHs (80-100 nm; L-CNHs) were chemically functionalized and radiolabeled with [(111)In]-diethylenetriaminepentaacetic acid and intravenously injected into mice. Their tissue distribution profiles at different time points were determined by single photon emission computed tomography/computed tomography. The results showed that the S-CNHs circulated longer in blood, while the L-CNHs accumulated faster in major organs like the liver and spleen. Small amounts of S-CNHs- and L-CNHs were excreted in urine within the first few hours postinjection, followed by excretion of smaller quantities within the next 48 hours in both urine and feces. The kinetics of excretion for S-CNHs were more rapid than for L-CNHs. Both S-CNH and L-CNH material accumulated mainly in the liver and spleen; however, S-...
Nature Communications, 2016
Medical Physics, 2015
Purpose: With recent advancement in hardware of optoacoustic imaging systems, highly detailed cro... more Purpose: With recent advancement in hardware of optoacoustic imaging systems, highly detailed cross-sectional images may be acquired at a single laser shot, thus eliminating motion artifacts. Nonetheless, other sources of artifacts remain due to signal distortion or out-of-plane signals. The purpose of image reconstruction algorithms is to obtain the most accurate images from noisy, distorted projection data. Methods: In this paper, the authors use the model-based approach for acoustic inversion, combined with a sparsity-based inversion procedure. Specifically, a cost function is used that includes the L1 norm of the image in sparse representation and a total variation (TV) term. The optimization problem is solved by a numerically efficient implementation of a nonlinear gradient descent algorithm. TV-L1 model-based inversion is tested in the cross section geometry for numerically generated data as well as for in vivo experimental data from an adult mouse. Results: In all cases, model-based TV-L1 inversion showed a better performance over the conventional Tikhonov regularization, TV inversion, and L1 inversion. In the numerical examples, the images reconstructed with TV-L1 inversion were quantitatively more similar to the originating images. In the experimental examples, TV-L1 inversion yielded sharper images and weaker streak artifact. Conclusions: The results herein show that TV-L1 inversion is capable of improving the quality of highly detailed, multiscale optoacoustic images obtained in vivo using cross-sectional imaging systems. As a result of its high fidelity, model-based TV-L1 inversion may be considered as the new standard for image reconstruction in cross-sectional imaging.
Optics letters, Jan 15, 2014
Multispectral optoacoustic tomography (MSOT) offers the potential to image in high-resolution cel... more Multispectral optoacoustic tomography (MSOT) offers the potential to image in high-resolution cells tagged with optical labels. In contrast to single wavelength imaging, multispectral excitation and spectral unmixing can differentiate labeled moieties over tissue absorption in the absence of background measurements. This feature can enable longitudinal cellular biology studies well beyond the depths reached by optical microscopy. However, the relation between spectrally resolved fluorescently labeled cells and optoacoustic detection has not been systematically investigated. Herein, we measured titrations of fluorescently labeled cells and establish the optoacoustic signal generated by these cells as a function of cell number and across different cell types. We then assess the MSOT sensitivity to resolve cells implanted in animals.
Journal of biophotonics, Jan 3, 2014
Molecular optoacoustic (photoacoustic) imaging typically relies on the spectral identification of... more Molecular optoacoustic (photoacoustic) imaging typically relies on the spectral identification of absorption signatures from molecules of interest. To achieve this, two or more excitation wavelengths are employed to sequentially illuminate tissue. Due to depth-related spectral dependencies and detection related effects, the multispectral optoacoustic tomography (MSOT) spectral unmixing problem presents a complex non-linear inversion operation. So far, different studies have showcased the spectral capacity of optoacoustic imaging, without however relating the performance achieved to the number of wavelengths employed. Overall, the dependence of the sensitivity and accuracy of optoacoustic imaging as a function of the number of illumination wavelengths has not been so far comprehensively studied. In this paper we study the impact of the number of excitation wavelengths employed on the sensitivity and accuracy achieved by molecular optoacoustic tomography. We present a quantitative ana...
Small, 2010
Carbon nanotubes (CNTs) consist of carbon atoms arranged in sheets of graphene rolled up into cyl... more Carbon nanotubes (CNTs) consist of carbon atoms arranged in sheets of graphene rolled up into cylindrical shapes. This class of nanomaterials has attracted attention because of their extraordinary properties, such as high electrical and thermal conductivity. In addition, development in CNT functionalization chemistry has led to an enhanced dispersibility in aqueous physiological media which indeed broadens the spectrum for their potential biological applications including gene delivery. The aim of this study is to determine the capability of different cationic polymergrafted multiwalled carbon nanotubes (MWNTs) (polymer-g-MWNTs) to effi ciently complex and transfer plasmid DNA (pCMVβ Gal) in vitro without promoting cytotoxicity. Carboxylated MWNT is chemically conjugated to the cationic polymers polyethylenimine (PEI), polyallylamine (PAA), or a mixture of the two polymers. In order to explore the potential of these polymer-g-MWNTs as gene delivery systems, we fi rst study their capacity to complex plasmid DNA (pDNA) using agarose gel electrophoresis. Gel migration studies confi rm pDNA binding to polymer-g-MWNT with different affi nities, highest for PEI-g-MWNT and PEI/PAA-g-CNT constructs. β-galactosidase expression is assessed in human lung epithelial (A549) cells, and the cytotoxicity is determined by modifi ed LDH assay after 24 h incubation period. Additionally, PEI-g-MWNT and/or PEI/PAA-g-MWNT reveal an improvement in gene expression when compared to the naked pDNA or to the equivalent amounts of PEI polymer alone. Mechanistically, pDNA was delivered by the polymerg-MWNT constructs via a different pathway compared to those used by polyplexes. In conclusion, polymer-g-MWNTs may be considered in the future as a versatile tool for effi cient gene transfer in cancer cells in vitro, provided their toxicological profi le is established. Nanomedicine A. Nunes et al.
PLoS ONE, 2013
The potential use of functionalized carbon nanotubes (f-CNTs) for drug and gene delivery to the c... more The potential use of functionalized carbon nanotubes (f-CNTs) for drug and gene delivery to the central nervous system (CNS) and as neural substrates makes the understanding of their in vivo interactions with the neural tissue essential. The aim of this study was to investigate the interactions between chemically functionalized multi-walled carbon nanotubes (f-MWNTs) and the neural tissue following cortical stereotactic administration. Two different f-MWNT constructs were used in these studies: shortened (by oxidation) amino-functionalized MWNT (oxMWNT-NH 3 +) and amino-functionalized MWNT (MWNT-NH 3 +). Parenchymal distribution of the stereotactically injected f-MWNTs was assessed by histological examination. Both f-MWNT were uptaken by different types of neural tissue cells (microglia, astrocytes and neurons), however different patterns of cellular internalization were observed between the nanotubes. Furthermore, immunohistochemical staining for specific markers of glial cell activation (GFAP and CD11b) was performed and secretion of inflammatory cytokines was investigated using real-time PCR (qRT-PCR). Injections of both f-MWNT constructs led to a local and transient induction of inflammatory cytokines at early time points. Oxidation of nanotubes seemed to induce significant levels of GFAP and CD11b over-expression in areas peripheral to the f-MWNT injection site. These results highlight the importance of nanotube functionalization on their interaction with brain tissue that is deemed critical for the development nanotube-based vector systems for CNS applications.
Nanomedicine, 2012
Aim: Carbon nanotubes (CNTs) are increasingly being utilized in neurological applications as comp... more Aim: Carbon nanotubes (CNTs) are increasingly being utilized in neurological applications as components of implants, electrodes or as delivery vehicles. Any application that involves implantation or injection of CNTs into the CNS needs to address the distribution and fate of the material following interaction and residence within the neuronal tissue. Here we report a preliminary study investigating the fate and structural integrity of amino-functionalized CNTs following stereotactic administration in the brain cortex. Materials & methods: The CNTs investigated had previously shown the capacity to internalize in various cell types of the CNS. An aqueous suspension of multiwalled CNT-NH3 + was stereotactically injected into the mouse brain cortex. Their interaction with neural cells and consequent effects on the CNT structural integrity was investigated by optical, transmission electron microscopy and Raman spectroscopy of brain tissue sections for a period between 2 and 14 days post ...
Proceedings of the National Academy of Sciences of the United States of America, Jan 5, 2011
Stroke is the second cause of death worldwide with ischemic stroke accounting for 80% of all stro... more Stroke is the second cause of death worldwide with ischemic stroke accounting for 80% of all stroke insults. Caspase-3 activation contributes to brain tissue loss and downstream biochemical events that lead to programmed cell death after traumatic brain injury. Alleviation of symptoms following ischemic neuronal injury can be potentially achieved by either genetic disruption or pharmacological inhibition of caspases. Here, we studied whether silencing of Caspase-3 using carbon nanotube-mediated in vivo RNA interference (RNAi) could offer a therapeutic opportunity against stroke. Effective delivery of siRNA directly to the CNS has been shown to normalize phenotypes in animal models of several neurological diseases. It is shown here that peri-lesional stereotactic administration of a Caspase-3 siRNA (siCas 3) delivered by functionalized carbon nanotubes (f-CNT) reduced neurodegeneration and promoted functional preservation before and after focal ischemic damage of the rodent motor cor...
Journal of Materials Chemistry, 2011
In this work we have synthesized a new series of cationic carbon nanotubes (CNTs) for siRNA bindi... more In this work we have synthesized a new series of cationic carbon nanotubes (CNTs) for siRNA binding. Both single-and multi-walled CNTs have been modified by addition or amidation reaction with short linear polyamine chains including putrescine, spermidine and spermine. All the new conjugates have been characterized with several spectroscopic and microscopic techniques. Their cytotoxic effects have been assessed on human lung carcinoma cell line. Finally, we have analyzed their capacity to bind siRNA towards the development of new carriers for gene silencing applications. The dispersibility properties and the capacity to complex siRNA of the different conjugates were found to be strongly dependent on the position of the functional groups on CNTs (i.e. mainly at the tips following the amidation reaction or on the sidewalls by direct CC addition).
Journal of Controlled Release, 2012
Treatment and diagnosis of neurodegenerative diseases and other CNS disorders are nowadays consid... more Treatment and diagnosis of neurodegenerative diseases and other CNS disorders are nowadays considered some of the most challenging tasks in modern medicine. The development of effective strategies for the prevention, diagnosis and treatment of CNS pathologies require better understanding of neurological disorders that is still lacking. The use of nanomaterials is thought to contribute to our further understanding of the CNS and the development of novel therapeutic and diagnostic modalities for neurological interventions. Even though the application of nanoparticles in neuroscience is still embryonic, this article attempts to illustrate the use of different types of nanomaterials and the way in which they have been used in various CNS applications in an attempt to limit or reverse neuropathological processes.
Chemical Communications, 2010
We have covalently grafted aptamers onto carboxylated carbon nanotubes to design a novel vector s... more We have covalently grafted aptamers onto carboxylated carbon nanotubes to design a novel vector system that can easily translocate into the cytosol of different cell types independent of receptor-mediated uptake. We propose the use of carbon nanotubes for the efficient intracellular delivery of biologically active aptamers for potential therapeutic applications.
Archives of Toxicology, 2012