RESUMO
Gd-L1 is a macrocyclic Gd-HPDO3A derivative functionalized with a short spacer to a trisulfonated pyrene. When compared to Gd-HPDO3A, the increased relaxivity appears to be determined by both the higher molecular weight and the occurrence of an intramolecularly catalyzed prototropic exchange of the coordinated OH moiety. In water, Gd-L1 displayed a relaxivity of 7.1 mM-1 s-1 (at 298 K and 0.5 T), slightly increasing with the concentration likely due to the onset of intermolecular aggregation. A remarkably high and concentration-dependent relaxivity was measured in human serum (up to 26.5 mM-1 s-1 at the lowest tested concentration of 0.005 mM). The acquisition of 1H-nuclear magnetic relaxation dispersion (NMRD) and 17O-R2 vs T profiles allowed to get an in-depth characterization of the system. In vitro experiments in the presence of human serum albumin, γ-globulins, and polylysine, as well as using media mimicking the extracellular matrix, provided strong support to the view that the trisulfonated pyrene fosters binding interactions with the exposed positive groups on the surface of proteins, responsible for a remarkable in vivo hyperintensity in T1w MR images. The in vivo MR images of the liver, kidneys, and spleen showed a marked contrast enhancement in the first 10 min after the i.v. injection of Gd-L1, which was 2-6-fold higher than that for Gd-HPDO3A, while maintaining a very similar excretion behavior. These findings may pave the way to an improved design of MRI GBCAs, for the first time, based on the setup of weak and dynamic interactions with abundant positive groups on serum and ECM proteins.
Assuntos
Meios de Contraste , Compostos Heterocíclicos , Compostos Organometálicos , Humanos , Meios de Contraste/química , Eletricidade Estática , Imageamento por Ressonância Magnética/métodos , Compostos Organometálicos/química , Pirenos , GadolínioRESUMO
The most prominent pathophysiological hallmark of Alzheimer's disease is the aggregation of amyloid-ß (Aß) peptides into senile plaques. Curcumin and its derivatives exhibit a high affinity for binding to Aß fibrils, effectively inhibiting their growth. This property holds promise for both therapeutic applications and diagnostic molecular imaging. In this study, curcumin was functionalized with perfluoro-tert-butyl groups to create candidate molecular probes specifically targeted to Aß fibrils for use in 19F-magnetic resonance imaging. Two types of fluorinated derivatives were considered: mono-substituted (containing nine fluorine atoms per molecule) and disubstituted (containing eighteen fluorine atoms). The linker connecting the perfluoro moiety with the curcumin scaffold was evaluated for its impact on binding affinity and water solubility. All mono-substituted compounds and one disubstituted compound exhibited a binding affinity toward Aß fibrils on the same order of magnitude as reference curcumin. The insertion of a charged carboxylate group into the linker enhanced the water solubility of the probes. Compound Curc-Glu-F9 (with one L-glutamyl moiety and a perfluoro-tert-butyl group), showed the best properties in terms of binding affinity towards Aß fibrils, water solubility, and intensity of the 19F-NMR signal in the Aß oligomer bound form.
Assuntos
Peptídeos beta-Amiloides , Curcumina , Placa Amiloide , Curcumina/química , Curcumina/farmacologia , Curcumina/síntese química , Peptídeos beta-Amiloides/metabolismo , Peptídeos beta-Amiloides/antagonistas & inibidores , Halogenação , Humanos , Solubilidade , Imagem por Ressonância Magnética de Flúor-19 , Estrutura MolecularRESUMO
Multimodality probes appear of great interest for innovative imaging applications in disease diagnosis. Herein, we present a chemical strategy enabling site-specific double-modification and cyclization of a peptide probe exploiting native chemical ligation (NCL) and thiol-maleimide addition. The synthetic strategy is straightforward and of general applicability for the development of double-labeled peptide multimodality probes.
Assuntos
Peptídeos , Compostos de Sulfidrila , Maleimidas/síntese química , Maleimidas/químicaRESUMO
The assessment of unregulated level of enzyme activity is a crucial parameter for early diagnoses in a wide range of pathologies. In this study, we propose the use of electron paramagnetic resonance (EPR) as an easy method to probe carboxylesterase (CE) enzymatic activity inâ vitro. For this application, were synthesized two amphiphilic, nitroxide containing esters, namely Tempo-C12 (T-C12) and Tempo-2-C12 (T-2-C12). They exhibit low solubility in water and form stable micelles in which the radicals are EPR almost silent, but the hydrolysis of the ester bond yields narrows and intense EPR signals. The intensity of the EPR signals is proportional to the enzymatic activity. CEs1, CEs2 and esterase from porcine liver (PLE) were investigated. The obtained results show that T-C12 and T-2-C12-containing systems display a much higher selectivity toward the CEs2, with a Limit of Detection of the same order of those ones obtained with optical methods.
Assuntos
Carboxilesterase , Ésteres , Animais , Espectroscopia de Ressonância de Spin Eletrônica/métodos , Ésteres/química , Hidrólise , Fígado , SuínosRESUMO
A total of 20% to 50% of prostate cancer (PCa) patients leave the surgery room with positive tumour margins. The intraoperative combination of fluorescence guided surgery (FGS) and photodynamic therapy (PDT) may be very helpful for improving tumour margin delineation and cancer therapy. PSMA is a transmembrane protein overexpressed in 90−100% of PCa cells. The goal of this work is the development of a PSMA-targeted Near InfraRed Fluorescent probe to offer the surgeon a valuable intraoperative tool for allowing a complete tumour removal, implemented with the possibility of using PDT to kill the eventual not resected cancer cells. PSMA-617 binding motif was conjugated to IRDye700DX-NHS and the conjugation did not affect the photophysical characteristics of the fluorophore. The affinity of IRDye700DX-PSMA-617 towards PCa cells followed the order of their PSMA expression, i.e., PC3-PIP > LNCaP > PC3, PC3-FLU. NIRF imaging showed a significant PC3-PIP tumour uptake after the injection of 1 or 5 nmol with a maximum tumour-to-muscle ratio (ca. 60) observed for both doses 24 h post-injection. Importantly, urine, healthy prostate, and the bladder were not fluorescent at 24 h post-injection. Flow cytometry and confocal images highlighted a co-localization of PSMA+ cells with IRDye700DX-PSMA uptake. Very interestingly, ex vivo analysis on a tumour specimen highlighted a significant PSMA expression by tumour-associated macrophages, likely attributable to extracellular vesicles secreted by the PSMA(+) tumour cells. FGS proved that IRDye700DX-PSMA was able to easily delineate tumour margins. PDT experiments showed a concentration-dependent decrease in cell viability (from 75% at 10 nM to 12% at 500 nM), whereas controls did not show any cytotoxicity. PC3-PIP tumour-bearing mice subjected to photodynamic therapy showed a delayed tumour growth. In conclusion, a novel PSMA-targeted NIRF dye with dual imaging-PDT capabilities was synthesized and displayed superior specificity compared to other small PSMA targeted molecules.
Assuntos
Fotoquimioterapia , Neoplasias da Próstata , Cirurgia Assistida por Computador , Animais , Humanos , Masculino , Camundongos , Antígenos de Superfície , Linhagem Celular Tumoral , Corantes Fluorescentes/farmacologia , Corantes Fluorescentes/uso terapêutico , Neoplasias da Próstata/diagnóstico por imagem , Neoplasias da Próstata/tratamento farmacológico , Neoplasias da Próstata/patologia , Cirurgia Assistida por Computador/métodosRESUMO
The N-capping region of an α-helix is a short N-terminal amino acid stretch that contributes to nucleate and stabilize the helical structure. In the VEGF mimetic helical peptide QK, the N-capping region was previously demonstrated to be a key factor of QK helical folding. In this paper, we explored the effect of the chiral inversion of the N-capping sequence on QK folding, performing conformational analysis in solution by circular dichroism and NMR spectroscopy. The effect of such a modification on QK stability in serum and the proliferative effect were also evaluated.
Assuntos
Aminoácidos , Fator A de Crescimento do Endotélio Vascular , Sequência de Aminoácidos , Peptídeos/química , Dicroísmo Circular , Conformação ProteicaRESUMO
The search for alternatives to Gd-containing magnetic resonance imaging (MRI) contrast agents addresses the field of Fe(III)-bearing species with the expectation that the use of an essential metal ion may avoid the issues raised by the exogenous Gd. Attention is currently devoted to highly stable Fe(III) complexes with hexacoordinating ligands, although they may lack any coordinated water molecule. We found that the hexacoordinated Fe(III) complex with two units of deferasirox, a largely used iron sequestering agent, owns properties that can make it a viable alternative to Gd-based agents. Fe(deferasirox)2 displays an outstanding thermodynamic stability, a high binding affinity to human serum albumin (three molecules of complex are simultaneously bound to the protein), and a good relaxivity that increases in the range 20-80 MHz. The relaxation enhancement is due to second sphere water molecules likely forming H-bonds with the coordinating phenoxide oxygens. A further enhancement was observed upon the formation of the supramolecular adduct with albumin. The binding sites of Fe(deferasirox)2 on albumin were characterized by relaxometric competitive assays. Preliminary in vivo imaging studies on a tumor-bearing mouse model indicate that, on a 3 T MRI scanner, the contrast ability of Fe(deferasirox)2 is comparable to the one shown by the commercial Gd(DTPA) agent. ICP-MS analyses on blood samples withdrawn from healthy mice administered with a dose of 0.1 mmol/kg of Fe(deferasirox)2 showed that the complex is completely removed in 24 h.
Assuntos
Meios de Contraste/química , Complexos de Coordenação/química , Deferasirox/análogos & derivados , Animais , Sítios de Ligação , Linhagem Celular Tumoral , Meios de Contraste/metabolismo , Meios de Contraste/farmacocinética , Complexos de Coordenação/metabolismo , Complexos de Coordenação/farmacocinética , Deferasirox/metabolismo , Deferasirox/farmacocinética , Feminino , Humanos , Ferro/química , Imageamento por Ressonância Magnética , Camundongos Endogâmicos BALB C , Ligação Proteica , Albumina Sérica Humana/química , Albumina Sérica Humana/metabolismoRESUMO
Herein, the synthesis and an extensive characterization of two novel Gd(AAZTA) (AAZTA=6-amino-6-methylperhydro-1,4-diazepine tetra acetic acid) derivatives functionalized with short (C2 and C4 ) n-alkyl acid functions are reported. The carboxylate functionality is the site for further conjugations for the design of more specific contrast agents (CAs). Interestingly, it has been found that the synthesized complexes display enhanced properties for use as MRI contrast agents on their own. The stability constants determined by using potentiometric titration and UV/Vis spectrophotometry were slightly higher than the one reported for the parent Gd(AAZTA) complex. This observation might be accounted for by the larger sigma-electron donation of the acyl substituents with respect to the one provided by the methyl group in the parent complex. As far as concerns the kinetic stability, transmetallation experiments with endogenous ions (e.g. Cu2+ ) implied that the Gd3+ ions present in these Gd(AAZTA) derivatives show somewhat smaller susceptibility to chemical exchange towards these ions at 25 °C, close to the physiological condition. The 1 Hâ NMR spectra of the complexes with EuIII and YbIII displayed a set of signals consistent with half the number of methylene protons present on each ligand. The number of resonances was invariant over a large range of temperatures, suggesting the occurrence of a fast interconversion between structural isomers. The relaxivity values (298â K, 20â MHz) were consistent with q=2 being equal to 8.8â mm-1 s-1 for the C2 derivative and 9.4â mm-1 s-1 for the C4 one, that is, sensibly larger than the one reported for Gd(AAZTA) (7.1â mm-1 s-1 ). Variable-temperature (VT)-T2 17 Oâ NMR measurements showed, for both complexes, the presence of two populations of coordinated water molecules, one in fast and one in slow exchange with the bulk water. As the high-resolution 1 Hâ NMR spectra of the analogs with EuIII and YbIII did not show the occurrence of distinct isomers (as frequently observed in other macrocyclic lanthanide(III)-containing complexes), we surmised the presence of two fast-interconverting isomers in solution. The analysis of the 17 Oâ NMR VT-T2 profiles versus temperature allowed their relative molar fraction to be established as 35 % for the isomer with the fast exchanging water and 65 % for the isomer with the water molecules in slower exchange. Finally, 1 Hâ NMRD profiles over an extended range of applied magnetic field strengths have been satisfactory fitted on the basis of the occurrence of the two interconverting species.
Assuntos
Meios de Contraste/química , Gadolínio/química , Imageamento por Ressonância Magnética/métodos , Compostos Organometálicos/química , PrótonsRESUMO
BACKGROUND: The combination of imaging and therapeutic agents in the same smart nanoparticle is a promising option to perform a minimally invasive imaging guided therapy. In this study, Low density lipoproteins (LDL), one of the most attractive biodegradable and biocompatible nanoparticles, were used for the simultaneous delivery of Paclitaxel (PTX), a hydrophobic antitumour drug and an amphiphilic contrast agent, Gd-AAZTA-C17, in B16-F10 melanoma cell line. These cells overexpress LDL receptors, as assessed by flow cytometry analysis. RESULTS: PTX and Gd-AAZTA-C17 loaded LDLs (LDL-PTX-Gd) have been prepared, characterized and their stability was assessed under 72 h incubation at 37 °C and compared to LDL loaded with Gd-AAZTA-C17 (LDL-Gd) and LDL-PTX. The cytotoxic effect of LDL-PTX-Gd was evaluated by MTT assay. The anti-tumour drug loaded into LDLs showed a significantly higher toxicity on B16-F10 cells with respect to the commercially available formulation Paclitaxel kabi (PTX Kabi) used in clinical applications. Tumour cells uptake was initially assessed by ICP-MS and MRI on B16-F10 cell line. By the analysis of the image signal intensity, it was possible to extrapolate the amount of internalized PTX indirectly by the decrease of relaxation times caused by Gd, proportional to its concentration. Finally, the treatment with PTX loaded LDL on B16-F10 tumour bearing mice resulted in a marked reduction of tumour growth compared to the administration of PTX Kabi alone. CONCLUSIONS: LDLs are selectively taken-up by tumour cells and can be successfully exploited for the selective delivery of Paclitaxel and imaging agents. For the first time the anon invasive "in vivo" determination of the amount of PTX accumulated in the tumour was possible, thanks to the use of theranostic agents of natural origin.
Assuntos
Imageamento por Ressonância Magnética/métodos , Nanopartículas/química , Paclitaxel/química , Medicina de Precisão/métodos , Animais , Antineoplásicos/química , Antineoplásicos/farmacologia , Materiais Biocompatíveis , Linhagem Celular Tumoral , Meios de Contraste , Sistemas de Liberação de Medicamentos/métodos , Lipoproteínas LDL/química , Fígado/patologia , Masculino , Melanoma Experimental/tratamento farmacológico , Camundongos , Camundongos Endogâmicos C57BL , Músculos/patologia , Neoplasias/tratamento farmacológico , Neoplasias/patologia , Tamanho da PartículaRESUMO
This study reports the development of a completely new class of MRI contrast agents, displaying remarkable relaxation effects in the absence of paramagnetic metal ions. Their detection requires the acquisition of images at variable magnetic field strength as provided by fast field cycling imaging scanners. They contain poly-histidine chains (poly-His), whose imidazole groups generate 14 N-quadrupolar-peaks that cause a relaxation enhancement of water protons at a frequency (1.38±0.3â MHz) that is readily detectable from the frequencies associated with endogenous proteins. The poly-His quadrupolar peaks are detectable only when the polymer is in a solid-like form, that is, at pH>6.6. Above this value, their intensity is pH dependent and can be used to report on the occurring pH changes. On this basis, the poly-His moieties were conjugated to biocompatible polymers, such as polylactic and glycolic acid, in order to form stable nanoparticles able to encapsulate structured water in their core. FFC images were acquired to assess their contrast-generating ability.
RESUMO
OBJECTIVE: The early embryo implantation is characterized by enhanced uterine vascular permeability at the site of blastocyst attachment, followed by extracellular-matrix remodeling and angiogenesis. Two TG (transglutaminase) isoenzymes, TG2 (tissue TG) and FXIII (factor XIII), catalyze covalent cross-linking of the extracellular-matrix. However, their specific role during embryo implantation is not fully understood. Approach and Results: For mapping the distribution as well as the enzymatic activities of TG2 and FXIII towards blood-borne and resident extracellular-matrix substrates, we synthetized selective and specific low molecular weight substrate analogs for each of the isoenzymes. The implantation sites were challenged by genetically modifying the trophoblast cells in the outer layer of blastocysts, to either overexpress or deplete TG2 or FXIII, and the angiogenic response was studied by dynamic contrast-enhanced-magnetic resonance imaging. Dynamic contrast-enhanced-magnetic resonance imaging revealed a decrease in the permeability of decidual vasculature surrounding embryos in which FXIII were overexpressed in trophoblast cell. Reduction in decidual blood volume fraction was demonstrated when either FXIII or TG2 were overexpressed in embryonic trophoblast cell and was elevated when trophoblast cell was depleted of FXIII. These results were corroborated by histological analysis. CONCLUSIONS: In this study, we report on the isoenzyme-specific roles of TG2 and FXIII during the early days of mouse pregnancy and further reveal their involvement in decidual angiogenesis. Our results reveal an important magnetic resonance imaging-detectable function of embryo-derived TG2 and FXIII on regulating maternal angiogenesis during embryo implantation in mice.Visual Overview: An online visual overview is available for this article.
Assuntos
Implantação do Embrião/fisiologia , Fator XIII/fisiologia , Proteínas de Ligação ao GTP/fisiologia , Imageamento por Ressonância Magnética/métodos , Neovascularização Fisiológica/fisiologia , Transglutaminases/fisiologia , Animais , Feminino , Fibrinogênio/fisiologia , Camundongos , Gravidez , Proteína 2 Glutamina gama-GlutamiltransferaseRESUMO
PURPOSE: Prostate cancer (PCa) is the most widespread tumor affecting males in Western countries. We propose a novel MRI molecular tetrameric probe based on the heptadentate gadolinium (Gd)-AAZTA (6-amino-6-methylperhydro-1,4-diazepinetetraacetic acid) that is able to in vivo detect PCa through the recognition of the fibrin-fibronectin (FB-FN) complex. METHODS: The peptide CREKA (Cys-Arg-Glu-Lys-Ala), targeting the FB-FN complex in the reactive stroma of the tumor, was synthesized by solid phase peptide synthesis (SPPS) and conjugated to the tetramer dL-(Gd-AAZTA)4 . The resulting probe was characterized by 1 H relaxometry, tested in vitro on FB clots and in vivo on an orthotopic mouse model of PCa. RESULTS: CREKA-dL-(Gd-AAZTA)4 showed a remarkable relaxivity of 18.2 m MGd-1s-1 (0.47 T, 25°C) because of the presence of 2 water molecules (q = 2) in the inner coordination sphere of each Gd3+ ion, whose rotational motion (τR ) is lengthened as the result of the relatively high molecular weight. The probe displayed a detectable affinity for plasma-derived FB clots. On intravenous injection of the probe in an orthotopic mouse model of PCa, a significant increase in the prostate T1 contrast (~40%) was observed. The MRI signal appears statistically higher either with respect to the one observed for the control probes and to the one detected when CREKA-dL-(Gd-AAZTA)4 was administered to healthy animals. CONCLUSIONS: This study demonstrated the ability of the CREKA-dL-(Gd-AAZTA)4 probe to specifically localize in prostate tumor after injection. The high relaxivity of the probe allows the reduction of the injected dose to 20 µmolGd /kg, yielding a good in vivo contrast enhancement in the region of prostate tumor.
Assuntos
Adenocarcinoma/diagnóstico por imagem , Meios de Contraste , Imageamento por Ressonância Magnética , Neoplasias da Próstata/diagnóstico por imagem , Acetatos/química , Adenocarcinoma/patologia , Animais , Azepinas/química , Biomarcadores Tumorais , Linhagem Celular Tumoral , Fibrina/química , Fibronectinas/química , Gadolínio/química , Humanos , Masculino , Camundongos , Camundongos Nus , Transplante de Neoplasias , Peptídeos/química , Neoplasias da Próstata/patologia , Ligação Proteica , Espectrometria de Massas por Ionização por ElectrosprayRESUMO
Molecular imaging requires the specific accumulation of contrast agents at the target. To exploit the superb resolution of MRI for applications in molecular imaging, gadolinium chelates, as the MRI contrast agents (CA), have to be conjugated to a specific vector able to recognize the epitope of interest. Several Gd(III)-chelates can be chemically linked to the same binding vector in order to deliver multiple copies of the CA (multimers) in a single targeting event thus increasing the sensitivity of the molecular probe. Herein three novel bifunctional agents, carrying one functional group for the bioconjugation to targeting vectors and four Gd(III)-AAZTA chelate functions for MRI contrast enhancement (AAZTA = 6-amino-6-methylperhydro-1,4-diazepinetetraacetic acid), are reported. The relaxivity in the tetrameric derivatives is 16.4 ± 0.2 mMGd-1 s-1 at 21.5 MHz and 25 °C, being 2.4-fold higher than that of parent, monomeric Gd(III)-AAZTA. These compounds can be used as versatile building blocks to insert preformed, high relaxivity, and high density Gd-centers to biological targeting vectors. As an example, we describe the use of these bifunctional Gd(III)-chelates to label a fibrin-targeting peptide.
Assuntos
Acetatos/síntese química , Azepinas/síntese química , Quelantes/síntese química , Meios de Contraste/síntese química , Gadolínio/química , Compostos Organometálicos/síntese química , Acetatos/química , Acetatos/metabolismo , Azepinas/química , Azepinas/metabolismo , Quelantes/química , Quelantes/metabolismo , Meios de Contraste/química , Meios de Contraste/metabolismo , Dimerização , Fibrina/metabolismo , Gadolínio/metabolismo , Humanos , Imageamento por Ressonância Magnética , Compostos Organometálicos/química , Compostos Organometálicos/metabolismo , Ligação ProteicaRESUMO
Purpose To evaluate the speciation of gadolinium-containing species after multiple administrations of the gadolinium-based contrast agents (GBCAs) gadodiamide and gadoteridol and to quantify the amount of intact gadolinium complexes and insoluble gadolinium-containing species. Materials and Methods A total dose of 13.2 mmol per kilogram of body weight of each GBCA was administered in healthy Wistar rats over a period of 8 weeks. Three days after the final administration, rats were sacrificed, and the brains were excised and divided into three portions. Each portion of brain homogenate was divided into two parts, one for determination of the total gadolinium concentration with inductively coupled plasma mass spectrometry and one for determination of the amount of intact GBCA and gadolinium-containing insoluble species. Relaxometric measurements of gadodiamide and gadolinium trichloride in the presence of polysialic acid were also performed. Results The mean total gadolinium concentrations for gadodiamide and gadoteridol, respectively, were 0.317 µg/g ± 0.060 (standard deviation) and 0.048 µg/g ± 0.004 in the cortex, 0.418 µg/g ± 0.078 and 0.051 µg/g ± 0.009 in the subcortical brain, and 0.781 µg/g ± 0.079 and 0.061 µg/g ± 0.012 in the cerebellum. Gadoteridol comprised 100% of the gadolinium species found in rats treated with gadoteridol. In rats treated with gadodiamide, the largest part of gadolinium retained in brain tissue was insoluble species. In the cerebellum, the amount of intact gadodiamide accounts for 18.2% ± 10.6 of the total gadolinium found therein. The mass balance found for gadolinium implies the occurrence of other soluble gadolinium-containing species (approximately 30%). The relaxivity of the gadolinium polysialic acid species formed in vitro was 97.8 mM/sec at 1.5 T and 298 K. Conclusion Gadoteridol was far less retained, and the entire detected gadolinium was intact soluble GBCA, while gadodiamide yielded both soluble and insoluble gadolinium-containing species, with insoluble species dominating. © RSNA, 2017 Online supplemental material is available for this article.
Assuntos
Encéfalo/metabolismo , Meios de Contraste/administração & dosagem , Meios de Contraste/farmacocinética , Gadolínio/administração & dosagem , Gadolínio/farmacocinética , Espectrofotometria Atômica/métodos , Animais , Química Encefálica , Meios de Contraste/química , Esquema de Medicação , Gadolínio/química , Masculino , Taxa de Depuração Metabólica , Especificidade de Órgãos/fisiologia , Ratos , Ratos Wistar , Solubilidade , Distribuição TecidualRESUMO
Polylactic and glycolic acid nanoparticles (PLGA-NPs), coated with L-ferritin, are exploited for the simultaneous delivery of paclitaxel and an amphiphilic Gd based MRI contrast agent into breast cancer cells (MCF7). L-ferritin has been covalently conjugated to the external surface of PLGA-NPs exploiting NHS activated carboxylic groups. The results confirmed that nanoparticles decorated with L-ferritin have many advantages with respect to both albumin-decorated and nondecorated particles. Ferritin moieties endow PLGA-NPs with targeting capability, exploiting SCARA5 receptors overexpressed by these tumor cells, that results in an increased paclitaxel cytotoxicity. Moreover, protein coating increased nanoparticle stability, thus reducing the fast and aspecific drug release before reaching the target. The theranostic potential of the nanoparticles has been demonstrated by evaluating the signal intensity enhancement on T1-weighted MRI images of labeled MCF7 cells. The results were compared with that obtained with MDA cells used as negative control due to their lower SCARA5 expression.
Assuntos
Portadores de Fármacos/química , Ferritinas/química , Nanopartículas/química , Paclitaxel/administração & dosagem , Ácido Poliglicólico/química , Antineoplásicos Fitogênicos/administração & dosagem , Neoplasias da Mama/diagnóstico por imagem , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/patologia , Meios de Contraste/administração & dosagem , Meios de Contraste/farmacocinética , Sistemas de Liberação de Medicamentos/métodos , Humanos , Células MCF-7 , Imageamento por Ressonância Magnética , Nanopartículas/uso terapêutico , Paclitaxel/farmacocinética , Receptores Depuradores Classe ARESUMO
Optoacoustic imaging emerged in early 1990s as a new biomedical imaging technology that generates images by illuminating tissues with short laser pulses and detecting resulting ultrasound waves. This technique takes advantage of the spectroscopic approach to molecular imaging, and delivers high-resolution images in the depth of tissue. Resolution of the optoacoustic imaging is scalable, so that biomedical systems from cellular organelles to large organs can be visualized and, more importantly, characterized based on their optical absorption coefficient, which is proportional to the concentration of absorbing chromophores. Optoacoustic imaging was shown to be useful in both preclinical research using small animal models and in clinical applications. Applications in the field of molecular imaging offer abundant opportunities for the development of highly specific and effective contrast agents for quantitative optoacoustic imaging. Recent efforts are being made in the direction of nontoxic biodegradable contrast agents (such as nanoparticles made of melanin) that are potentially applicable in clinical optoacoustic imaging. In order to increase the efficiency and specificity of contrast agents and probes, they need to be made smart and capable of controlled accumulation in the target cells. This review was written in recognition of the potential breakthroughs in medical optoacoustic imaging that can be enabled by efficient and nontoxic melanin-based optoacoustic contrast agents.
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Meios de Contraste , Diagnóstico por Imagem , Melaninas/metabolismo , Imagem Molecular , Técnicas Fotoacústicas , Nanomedicina Teranóstica , Animais , Diagnóstico por Imagem/métodos , Humanos , Imagem Molecular/métodos , Sondas Moleculares , Imagem Multimodal/métodos , Neoplasias/diagnóstico por imagem , Neoplasias/metabolismo , Neoplasias/patologia , Nanomedicina Teranóstica/métodosRESUMO
Inflammation is signaled by the overexpression of epitopes on the vascular endothelium that primarily aim at recruiting immune cells into the inflamed area. The intravascular localization of these biomarkers makes them suitable targets for the MRI visualization of inflammation. Phospholipid-based nanosystems appear excellent candidates in virtue of their good biocompatibility, ability to deliver a high number of imaging units at the target site, and for the easy functionalization with targeting vectors. In this work, phospholipid-based micelles (hydrodynamic diameter of 20 nm) loaded with the amphiphilic Gd(III)-complex Gd-DOTAMA(C18)2 were vectorized with a small peptide able to specifically bind VCAM-1 receptors. The micelles displayed a high longitudinal relaxivity (36.4 s(-1)mmolGd(-1) at 25 °C and 0.7 T). A (1)H- and (17)O-water relaxometry study indicated that the paramagnetic complex embedded in the nanoparticles adopted two isomeric conformations, likely reflecting the well-known square antiprismatic (SAP) and twisted square antiprismatic (TSAP) configurations typically observed in DOTA-like lanthanide complexes. Interestingly, the TSAP structure, showing a much faster exchange rate for the water molecule coordinated to the metal ion, was the most abundant, thus explaining the high relaxivity of the micellar agent. The systemic administration of the micelles into a lipopolysaccharide-induced murine model of acute inflammation successfully demonstrated the ability of the targeting agents to detect the diseased area by T1 contrast enhanced MRI.
Assuntos
Imageamento por Ressonância Magnética/métodos , Imãs/química , Micelas , Fosfolipídeos/química , Fosfolipídeos/metabolismo , Molécula 1 de Adesão de Célula Vascular/metabolismo , Animais , Inflamação/induzido quimicamente , Inflamação/diagnóstico por imagem , Inflamação/metabolismo , Lipopolissacarídeos/farmacologia , Camundongos , Polietilenoglicóis/químicaRESUMO
Magnetic iron oxide nanoparticles (Fe-NPs) can be exploited in biomedicine as agents for magnetic fluid hyperthermia (MFH) treatments and as contrast enhancers in magnetic resonance imaging. New, oleate-covered, iron oxide particles have been prepared either by co-precipitation or thermal decomposition methods and incorporated into poly(lactic-co-glycolic acid) nanoparticles (PLGA-Fe-NPs) to improve their biocompatibility and in vivo stability. Moreover, the PLGA-Fe-NPs have been loaded with paclitaxel to pursue an MFH-triggered drug release. Remarkably, it has been found that the nanoparticle formulations are characterized by peculiar (1)H nuclear magnetic relaxation dispersion (NMRD) profiles that directly correlate with their heating potential when exposed to an alternating magnetic field. By prolonging the magnetic field exposure to 30 min, a significant drug release was observed for PLGA-Fe-NPs in the case of the larger-sized magnetic nanoparticles. Furthermore, the immobilization of lipophilic Fe-NPs in PLGA-NPs also made it possible to maintain Néel relaxation as the dominant relaxation contribution in the presence of large iron oxide cores (diameters of 15-20 nm), with the advantage of preserving their efficiency when they are entrapped in the intracellular environment. The results reported herein show that NMRD profiles are a useful tool for anticipating the heating capabilities of Fe-NPs designed for MFH applications.
RESUMO
Glucan particles (GPs) are monodisperse microspheres derived from baker's yeast and represent an interesting class of microcarriers for theranostic applications as they show a high affinity toward immune system cells. The typical loading strategy was to harness the ability of the molecule to be loaded to interact with nano-/microassembled systems through electrostatic or hydrophobic forces. However, small water-soluble chemicals could not be steadily retained by the leaky shell of GPs. In this work, we propose an alternative loading approach for small water-soluble compounds that is based on their entrapment in the aqueous core of liposomes that are directly formed into the microparticles through the reverse phase evaporation method (REV). The construct obtained may act as biocompatible carrier to deliver and release, even in a triggerable way, bioactive compounds.
Assuntos
Glucanos/química , Lipossomos/química , Água/química , Microesferas , Tamanho da Partícula , SolubilidadeRESUMO
Quantitative measurement of marker expression in diseased cells is still a topic of considerable interest and different methodologies are currently under intense scrutiny. This work aims at developing an inâ vitro diagnostic method based on the release of paramagnetic species from relaxometrically "silent" liposomes operated by the action of a phospholipase A2 (PLA2) previously targeted to the epitope of interest. The released paramagnetic species causes an increase of the longitudinal water proton relaxation rate proportional to the number of PLA2 bound to the cell outer surface. The sensitivity of the herein proposed method, named R-ELISA, was attempted in the detection of folate receptor expression on human ovarian cancer cells by functionalizing PLA2 with folic acid. Receptor/cell number of 8.3×10(5) has been measured on IGROV-1 cells. The R-ELISA assay can detect nanomolar cell suspension receptor concentrations and has been validated by well-established spectrofluorimetric procedures.