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1.
Molecules ; 26(15)2021 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-34361832

RESUMO

In recent times, researchers have aimed for new strategies to combat cancer by the implementation of nanotechnologies in biomedical applications. This work focuses on developing protein-based nanoparticles loaded with a newly synthesized NIR emitting and absorbing phthalocyanine dye, with photodynamic and photothermal properties. More precisely, we synthesized highly reproducible bovine serum albumin-based nanoparticles (75% particle yield) through a two-step protocol and successfully encapsulated the NIR active photosensitizer agent, achieving a good loading efficiency of 91%. Making use of molecular docking simulations, we confirm that the NIR photosensitizer is well protected within the nanoparticles, docked in site I of the albumin molecule. Encouraging results were obtained for our nanoparticles towards biomedical use, thanks to their negatively charged surface (-13.6 ± 0.5 mV) and hydrodynamic diameter (25.06 ± 0.62 nm), favorable for benefitting from the enhanced permeability and retention effect; moreover, the MTT viability assay upholds the good biocompatibility of our NIR active nanoparticles. Finally, upon irradiation with an NIR 785 nm laser, the dual phototherapeutic effect of our NIR fluorescent nanoparticles was highlighted by their excellent light-to-heat conversion performance (photothermal conversion efficiency 20%) and good photothermal and size stability, supporting their further implementation as fluorescent therapeutic agents in biomedical applications.


Assuntos
Indóis/administração & dosagem , Nanopartículas/administração & dosagem , Neoplasias Ovarianas/tratamento farmacológico , Fotoquimioterapia/métodos , Fármacos Fotossensibilizantes/administração & dosagem , Soroalbumina Bovina/química , Proliferação de Células , Feminino , Humanos , Indóis/química , Luz , Simulação de Acoplamento Molecular , Nanopartículas/química , Neoplasias Ovarianas/patologia , Fármacos Fotossensibilizantes/química , Espectroscopia de Luz Próxima ao Infravermelho , Células Tumorais Cultivadas
2.
Biomater Sci ; 9(18): 6183-6202, 2021 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-34346411

RESUMO

Among women, ovarian cancer is the fifth most frequent type of cancer, and despite benefiting from current standard treatment plans, 90% of patients relapse in the subsequent 18 months and, eventually, perish. As a result, via embracing nanotechnological advancements in the field of medical science, researchers working in the areas of cancer therapy and imaging are looking for the next breakthrough treatment strategy to ensure lower cancer recurrence rates and improved outcomes for patients. Herein, we design a novel phototheranostic agent with optical features in the biological window of the electromagnetic spectrum via encapsulating a newly synthesized phthalocyanine dye within biocompatible protein nanoparticles, allowing the targeted fluorescence imaging and synergistic dual therapy of ovarian cancer. The nanosized agent displays great biocompatibility and enhanced aqueous biostability and photothermal activity, as well as high reactive-oxygen-species generation efficiency. To achieve the active targeting of the desired malignant tissue and suppress the rapid clearance of the photosensitive agent from the peritoneal cavity, the nanoparticles are biofunctionalized with an anti-folate receptor antibody. A2780 ovarian cancer cells are employed to confirm the improved targeting capabilities and the in vitro cytotoxic efficiency of the theranostic nanoparticles after exposure to a 660 nm LED lamp; upon measurement via MTT and flow cytometry assays, a significant 95% decrease in the total number of viable cells is seen. Additionally, the therapeutic performance of our newly designed nanoparticles was evaluated in vivo, via real-time thermal monitoring and histopathological assays, upon the irradiation of tumour-bearing mice with a 660 nm LED lamp (0.05 W cm-2). Foremost, separately from steady-state fluorescence imaging, we found that, via utilizing FLIM investigations, the differences in fluorescence lifetimes of antibody biofunctionalized and non-functionalized nanoparticles can be correlated to different intracellular localization and internalization pathways of the fluorescent agent, which is relevant for the development of a cutting-edge method for the detection of cancer cells that overexpress folate receptors at their surfaces.


Assuntos
Nanopartículas , Neoplasias Ovarianas , Animais , Linhagem Celular Tumoral , Feminino , Humanos , Camundongos , Imagem Óptica , Neoplasias Ovarianas/diagnóstico por imagem , Neoplasias Ovarianas/tratamento farmacológico , Fototerapia , Medicina de Precisão , Nanomedicina Teranóstica
3.
Artigo em Inglês | MEDLINE | ID: mdl-34068152

RESUMO

INTRODUCTION: During the last three decades, there has been an excess weight epidemic due to changes in nutrition and lifestyle. Few data on the prevalence of overweight and obesity in children in Romania were published, without a single study representative at the national level. There are reports on the higher level of overweight and obesity in urban areas compared to rural ones. This study aimed to estimate the prevalence of underweight, overweight, obesity and severe obesity in children enrolled in schools from the urban area. MATERIAL AND METHODS: For this cross-sectional study, children from 177 schools from the urban area of five counties from the northwestern part of Romania were included after the parents signed written informed consent. Anthropometric data were recorded (weight, height) based on World Health Organization (WHO) recommendations and Body-Mass-Index (BMI), and the z-score for BMI were calculated. The nutritional status was estimated using three reference criteria: WHO, International Obesity Task Force (IOTC) and the Center for Disease Control and Prevention (CDC). RESULTS: We analyzed data of 21,650 children (48.19% boys) age between 7 and 18 years. The prevalence of overweight was 13.8%, 16.2% and 20.3%, of obesity was 10.7%, 10.0% and 5.7% and of severe obesity was 5.1%, 1.2% and 1.6% (using WHO, CDC and IOTF cut-offs). Underweight was present in 5.2% (WHO), 6% (CDC) and 2.6% (IOTF). The highest prevalence of overweight (including obesity) was found in children aged 10 years, and the lowest in adolescents at 18 years. Boys have a higher prevalence of excess weight than girls. Using IOTF cut-offs, the prevalence of obesity and severe obesity was lower than using WHO criteria. CONCLUSIONS: The prevalence of overweight (including obesity) in children from the urban area of Western Romania was recorded at alarming levels, higher in boys and at the pre-puberty ages. There are significant differences based on the reference system used. It is important to correctly choose the reference for the definition of overweight and obesity to have the correct estimation of the target for public health measures.


Assuntos
Obesidade Pediátrica , Adolescente , Índice de Massa Corporal , Criança , Estudos Transversais , Feminino , Humanos , Masculino , Sobrepeso/epidemiologia , Obesidade Pediátrica/epidemiologia , Prevalência , Romênia/epidemiologia , Instituições Acadêmicas , Magreza/epidemiologia
4.
PLoS One ; 16(4): e0248922, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33909622

RESUMO

Colorectal cancer remains one of the most frequent malignancies (third place at both genders) worldwide in the last decade, owing to significant changes in modern dietary habits. Approximately half of the patients develop metastases during the course of their disease. The available therapeutic armamentarium is constantly evolving, raising questions regarding the best approach for improving survival. Bevacizumab remains one of the most widely used therapies for treating metastatic colorectal cancer and can be used after progression. This study aimed to identify the best chemotherapy partner for bevacizumab after progression. We performed a retrospective analysis of patients with metastatic colorectal cancer who were treated with bevacizumab as first- and second-line chemotherapy. Data were collected for 151 patients, 40 of whom were treated with double-dose bevacizumab after the first progression. The two standard chemotherapy regimens combined with bevacizumab were FOLFIRI/CAPIRI and FOLFOX4/CAPEOX. The initiation of first-line treatment with irinotecan-based chemotherapy improved progression-free survival and time to treatment failure but not overall survival. After the first progression, retreatment with the same regimen as that used in the induction phase was the best approach for improving overall survival (median overall survival: 46.5 vs. 27.0 months for the same vs. switched strategy, respectively). No correlations were observed between the dose intensity of irinotecan, oxaliplatin, 5-fluorouracil, or bevacizumab and the overall survival, progression-free survival in the first-/second-line treatment, and time to treatment failure. Interaction between an irinotecan-based regimen as a second-line treatment and double-dose bevacizumab after progression was associated with an improved overall survival (p = 0.06). Initiating systemic treatment with an irinotecan-based regimen in combination with bevacizumab improved the progression-free survival in the first-line treatment and time to treatment failure. In terms of overall survival, bevacizumab treatment after the first progression is better partnered with the same regimen as that used in the induction phase.


Assuntos
Antineoplásicos/uso terapêutico , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Bevacizumab/uso terapêutico , Neoplasias Colorretais/tratamento farmacológico , Irinotecano/uso terapêutico , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Intervalo Livre de Progressão , Estudos Retrospectivos , Adulto Jovem
5.
Int J Nanomedicine ; 16: 2147-2171, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33746512

RESUMO

The use of fluorescence imaging technique for visualization, resection and treatment of cancerous tissue, attained plenty of interest once the promise of whole body and deep tissue near-infrared (NIR) imaging emerged. Why is NIR so desired? Contrast agents with optical properties in the NIR spectral range offer an upgrade for the diagnosis and treatment of cancer, by dint of the deep tissue penetration of light in the NIR region of the electromagnetic spectrum, also known as the optical window in biological tissue. Thus, the development of a new generation of NIR emitting and absorbing contrast agents able to overcome the shortcomings of the basic free dye administration is absolutely essential. Several examples of nanoparticles (NPs) have been successfully implemented as carriers for NIR dye molecules to the tumour site owing to their prolonged blood circulation time and enhanced accumulation within the tumour, as well as their increased fluorescence signal relative to free fluorophore emission and active targeting of cancerous cells. Due to their versatile structure, good biocompatibility and capability to efficiently load dyes and bioconjugate with diverse cancer-targeting ligands, the research area of developing protein-based NPs encapsulated or conjugated with NIR dyes is highly promising but still in its infancy. The current review aims to provide an up-to-date overview on the biocompatibility, specific targeting and versatility offered by protein-based NPs loaded with different classes of NIR dyes as next-generation fluorescent agents. Moreover, this study brings to light the newest and most relevant advances involving the state-of-the-art NIR fluorescent agents for the real-time interventional NIR fluorescence imaging of cancer in clinical trials.


Assuntos
Corantes/química , Retroalimentação , Raios Infravermelhos , Nanopartículas/química , Neoplasias/diagnóstico por imagem , Neoplasias/cirurgia , Proteínas/química , Animais , Fluorescência , Humanos
6.
J BUON ; 25(2): 875-883, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32521881

RESUMO

PURPOSE: Bevacizumab or cetuximab represent the standard treatment in association with classical chemotherapy in confirmed metastatic colorectal cancer (mCRC). Bevacizumab could be continued after the first disease progression with an overall survival (OS) advantage, compared to chemotherapy alone, but the optimal dose remains a debatable issue. METHODS: In a retrospective analysis of mCRC patients treated with bevacizumab, we selected patients with administration beyond progression, and stratified them according to the dose received- same dose bevacizumab (SDB) as first-line chemotherapy or double dose bevacizumab (DDB). For each group we evaluated OS, time to treatment failure (TTF) and progression-free survival in the first-line (PFS1) and in the second-line (PFS2). RESULTS: In the first-line therapy, oxaliplatin backbone regimen was used in 73% SDB, compared with 22.5% DDB patients, while irinotecan was used in 75% DDB and 27% SDB patients. Second-line oxaliplatin was given to 50% DDB and 29.7% SDB patients, while irinotecan was administered to 47.5% DDB and 70.3% SDB patients. The median values were: OS - 41 months in the DDB group and 25 months in the SDB group (p = 0.01); TTF - 24 months in the DDB group and 19 months in the SDB group (p=0.009); PFS1 - 17 months in the DDB group and 12 months in the SDB group (p=0.008); PFS2 - 9 months in the DDB group and 5 months in the SDB group (p = 0.03). CONCLUSIONS: Doubling the dose of bevacizumab at progression seems to provide OS and PFS advantage for mCRC patients.


Assuntos
Bevacizumab/uso terapêutico , Neoplasias Colorretais/tratamento farmacológico , Relação Dose-Resposta a Droga , Adulto , Idoso , Bevacizumab/farmacologia , Progressão da Doença , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Metástase Neoplásica , Estudos Retrospectivos
7.
Nanotechnology ; 31(31): 315102, 2020 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-32315999

RESUMO

Nowadays, extensive research is being carried out to find innovative solutions for the development of stable, reproductible, and highly efficient fluorescent contrast agents with the ability of targeting specific cells, which can be further implemented for fluorescent-guided surgery in a real clinical setting. The present study is focused on the development of fluorescent dye-loaded protein nanoparticles (NPs) to overcome the drawbacks of the standard administration of free organic fluorophores, such as cytotoxicity, aqueousinstability, and rapid photo-degradation. Precisely, human serum albumin (HSA) NPs loaded with two different FDA approved dyes, namely indocyanine green (ICG) and fluorescein isothiocyanate (FITC), with a fluorescence response in the near-infrared and visible spectral domains, respectively, have been successfully designed. Even though the diameter of fluorescent HSA NPs is around 30 nm as proven by dynamic light scattering and transmission electron microscopy investigations, they present good loading efficiencies of almost 50% for ICG, and over 30% for FITC and a high particle yield of over 75%. Molecular docking simulations of ICG and FITC within the structure of HSA confirmed that the dyes were loaded inside the NPs, and docked in Site I (subdomain IIA) of the HSA molecule. After the confirmation of their high fluorescence photostability, the NPs were covalently conjugated with folic acid (HSA-FA NPs) in order to bind specifically to the folate receptor alpha (FRα) protein overexpressed on NIH:OVCAR3 ovarian cancer cells. Finally, fluorescence microscopy imaging investigations validate the improved internalization of folate targeted HSA&FITC NPs compared to cells treated with untargeted ones. Furthermore, TEM examinations of the distribution of HSA NPs into the NIH:OVCAR3 cells revealed anincreased number of NP-containing vesicles for the cells treated with HSA-FA NPs, compared to the cells exposed to untargeted HAS NPs, upholding the enhanced cellular uptake through FRα-mediated potocytosis.


Assuntos
Receptor alfa de Estrogênio/metabolismo , Corantes Fluorescentes/química , Ácido Fólico/farmacologia , Neoplasias Ovarianas/metabolismo , Albumina Sérica Humana/química , Linhagem Celular Tumoral , Sobrevivência Celular , Feminino , Fluoresceína-5-Isotiocianato/química , Ácido Fólico/química , Humanos , Verde de Indocianina/química , Simulação de Acoplamento Molecular , Nanopartículas , Regulação para Cima
8.
Front Chem ; 7: 55, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30800650

RESUMO

In this work, we design new plasmonic paper-based nanoplatforms with interesting capabilities in terms of sensitivity, efficiency, and reproducibility for promoting multimodal biodetection via Localized Surface Plasmon Resonance (LSPR), Surface Enhanced Raman Spectroscopy (SERS), and Metal Enhanced Fluorescence (MEF). To succeed, we exploit the unique optical properties of gold nanobipyramids (AuBPs) deposited onto the cellulose fibers via plasmonic calligraphy using a commercial pen. The first step of the biosensing protocol was to precisely graft the previously chemically-formed p-aminothiophenol@Biotin system, as active recognition element for target streptavidin detection, onto the plasmonic nanoplatform. The specific capture of the target protein was successfully demonstrated using three complementary sensing techniques. As a result, while the LSPR based sensing capabilities of the nanoplatform were proved by successive 13-18 nm red shifts of the longitudinal LSPR associated with the change of the surface RI after each step. By employing the ultrasensitive SERS technique, we were able to indirectly confirm the molecular identification of the biotin-streptavidin interaction due to the protein fingerprint bands assigned to amide I, amide III, and Trp vibrations. Additionally, the formed biotin-streptavidin complex acted as a spacer to ensure an optimal distance between the AuBP surface and the Alexa 680 fluorophore for achieving a 2-fold fluorescence emission enhancement of streptavidin@Alexa 680 on the biotinylated nanoplatform compared to the same complex on bare paper (near the plasmonic lines), implementing thus a novel MEF sensing nanoplatform. Finally, by integrating multiple LSPR, SERS, and MEF nanosensors with multiplex capability into a single flexible and portable plasmonic nanoplatform, we could overcome important limits in the field of portable point-of-care diagnostics.

9.
J BUON ; 23(3): 800-813, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30003755

RESUMO

PURPOSE: Glioblastoma is a rapidly evolving lethal disease mainly due to its highly chemo- and radioresistant glioblastoma stem cells (GSCs). Herein, we tested if chitosan-capped gold nanoparticles (Chit-GNPs) may overcome the limitations of drug concentrations by increased cell internalization in GSCs and if such GNPs could enhance the response to irradiation. METHODS: Chitosan was used for Chit-GNP synthesis as a reducing and stabilizing agent. Chit-GNPs were characterized by spectroscopy, dark field, transmission electron microscopy and zeta potential measurements. Patient-derived GSCs and human osteoblasts were treated with increasing concentrations of nanoparticles and irradiated. The uptake and cytotoxicity of Chit-GNPs were compared to that of uncoated GNPs. RESULTS: The positively-charged, 26 nm-sized, spherical Chit-GNPs, showed a huge intracellular accumulation into the cytosol, lysosomes and near the nucleus, whereas no uncoated GNPs were internalized within GSCs. Surprisingly, Chit-GNPs were highly cytotoxic for GSCs irrespective of cell irradiation, that failed to add an additional benefit when combined with Chit-GNPs/GNPs. Moreover, Chit-GNPs were selectively cytotoxic for GSCs and did not affect the normal cells, despite an increased nanoparticle internalization. CONCLUSIONS: The important Chit-GNP internalization and their selective cytotoxicity for GSCs make this compound a potential novel anticancer agent and a promising backbone for drug delivery in glioblastoma.


Assuntos
Quitosana/administração & dosagem , Glioblastoma/tratamento farmacológico , Ouro/administração & dosagem , Nanopartículas Metálicas/administração & dosagem , Células-Tronco/efeitos dos fármacos , Linhagem Celular Tumoral , Sistemas de Liberação de Medicamentos/métodos , Humanos
10.
Anal Chem ; 90(14): 8567-8575, 2018 07 17.
Artigo em Inglês | MEDLINE | ID: mdl-29902917

RESUMO

In this work, we demonstrate the feasibility of gold bipyramidal-shaped nanoparticles (AuBPs) to be used as active plasmonic nanoplatforms for the detection of the biotin-streptavidin interaction in aqueous solution via both Localized Surface Plasmon Resonance and Surface Enhanced Raman Scattering (LSPR/SERS). Our proof of concept exploits the precise attachment of the recognition element at the tips of AuBPs, where the electromagnetic field is stronger, which is beneficial to the surface sensitivity of longitudinal LSPR on the local refractive index and to the electromagnetic enhancement of SERS activity, too. Indeed, successive red shifts of the longitudinal LSPR associated with increased local refractive index reveal the attachment of para-aminothiophenol (p-ATP) chemically labeled Biotin to the Au surface and the specific capture of the target protein by biotin-functionalized AuBPs. Finite-Difference Time-Domain simulations based on the reconstructed index of refraction confirm LSPR measurements. However, the molecular identification of the biotin-streptavidin interaction remains elusive by LSPR investigation alone. Remarkably, we succeeded to complement the LSPR detection with reliable SERS measurements which permitted to (a) certify the molecular identification of biotin-streptavidin interaction and (b) extend the limit of detection of streptavidin in solution toward 10-12 M. Finally, to further probe the possibility to implement the AuBPs as dual LSPR-SERS based immunoassays in solution for real clinical diagnostics, we additionally investigated the AuBP's performance to transduce the specific antihuman IgG- human IgG binding event, providing thus a reference design for building unique plasmonic immunoassays for dual-optical detection of target proteins in aqueous solution.


Assuntos
Técnicas Biossensoriais/instrumentação , Ouro/química , Imunoensaio/instrumentação , Imunoglobulina G/análise , Análise Espectral Raman/instrumentação , Ressonância de Plasmônio de Superfície/instrumentação , Biotina/química , Humanos , Estreptavidina/química
11.
Biosens Bioelectron ; 86: 728-735, 2016 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-27476053

RESUMO

In this manuscript we propose a simple and efficient strategy to improve the sensitivity of localized surface plasmon resonance (LSPR) shift-based biosensors using biotin-streptavidin recognition interaction as a proof-of-concept. Specifically, biotin molecules are immobilized on a low-cost plasmonic LSPR biosensor based on annealed self-assembled spherical gold nanoparticles (AuNSs) and successively incubated with increasing concentrations of streptavidin, achieving a limit of detection (LOD) of 5nM. Interestingly, when the detection is performed by the same biotin-functionalized plasmonic AuNSs substrate but against streptavidin previously conjugated to gold nanorods, the LSPR shift is 26-fold enhanced. Moreover, we confirm these results through numerical simulations and demonstrate that the proposed sensing architecture can operate as transducer not only to confirm the adsorption of bioanalyte but also to provide the chemical identity of the capture and targeted molecules from their vibrational Raman fingerprints. Therefore, we are confident that the development of such plasmonic biosensors that use metallic labels for improving the sensitivity of detection could become highly promising for future point-of-care diagnostic assays, pushing sensitivity towards single-molecule detection limit.


Assuntos
Reações Antígeno-Anticorpo/imunologia , Biotina/imunologia , Imunoensaio/instrumentação , Nanotubos/química , Estreptavidina/imunologia , Ressonância de Plasmônio de Superfície/instrumentação , Técnicas Biossensoriais/instrumentação , Biotina/análise , Desenho de Equipamento , Análise de Falha de Equipamento , Ouro , Nanotecnologia/instrumentação , Nanotubos/ultraestrutura , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Estreptavidina/análise
12.
ACS Appl Mater Interfaces ; 8(35): 22900-13, 2016 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-27537061

RESUMO

In this work, we developed a new pH- and temperature-responsive nanochemotherapeutic system based on Doxorubicin (DOX) noncovalently bound to biosynthesized gelatin-coated gold nanoparticles (DOX-AuNPs@gelatin). The real-time release profile of DOX was evaluated at different pH values (7.4, 5.3, and 4.6) and temperatures (22-45 °C) in aqueous solutions, and its therapeutic performance was examined in vitro against MCF-7 breast cancer cells. TEM, dark-field scattering, and wide-field fluorescence microscopy indicated the effective uptake of nanochemotherapeutics with the subsequent release and progressive accumulation of DOX in cell nuclei. MTT assays clearly showed the effectiveness of the treatment by inhibiting the growth of MCF-7 breast cancer cells for a loaded drug concentration of 5 µg/mL. The most informative data about the dynamic release and localization were provided by scanning confocal microscopy using time-resolved fluorescence and surface-enhanced Raman scattering (SERS) techniques. In particular, fluorescence-lifetime imaging (FLIM) recorded under 485 nm pulsed diode laser excitation revealed the bimodal distribution of DOX in cells. The shorter fluorescence lifetime of DOX localized in nuclei (1.52 ns) than in the cytoplasm (2.4 ns) is consistent with the cytotoxic mechanism induced by DOX-DNA intercalation. Remarkably, the few DOX molecules captured between nanoparticles ("electromagnetic hotspots") after most drug is released act as SERS reporters for the localization of plasmonic nanocarriers in MCF-7 cells. The high drug loading capacity and effective drug release under pH control combined with the advantage of multimodal visualization inside cells clearly indicate the high potential of our DOX-AuNPs@gelatin delivery system for implementation in nanomedicine.


Assuntos
Nanopartículas Metálicas , Doxorrubicina , Portadores de Fármacos , Composição de Medicamentos , Sistemas de Liberação de Medicamentos , Gelatina , Ouro , Concentração de Íons de Hidrogênio , Imagem Multimodal
13.
Colloids Surf B Biointerfaces ; 132: 122-31, 2015 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-26037701

RESUMO

It is useful to find new methods to synthesize and, more importantly, to control the size and shape of gold nanoparticles (AuNPs) without using relatively toxic-reducing agents and surfactants. In this work, we present a one-pot, green synthesis of AuNPs taking the advantage of gelatin biopolymer to operate as unique reducing, growth controlling and stabilizing agent in aqueous solution of tetrachloroauric acid (HAuCl4) at temperatures above its melting point (∼35°C). The shape and size of AuNPs were found to be strongly influenced by the gelatin concentration (0.5-5%), while the growth rate of AuNPs is controlled by temperature of synthesis (40-80°C) and viscosity of the biopolymer. A specific class of gelatin-coated AuNPs was selected to investigate its stability in simulated physiological conditions and cellular media and subsequently to evaluate the in vitro biocompatibility and capacity to sustain proliferation and differentiation of Osteoblast cells. Dark-field microscopy and Rayleigh scattering spectra prove a more efficient internalization of gelatin-coated AuNPs as compared with citrate-coated AuNPs, while methylthiazoltetrazolium bromide (MTT) assay demonstrates enhanced cell proliferation. Interestingly, in the presence of gelatin-coated AuNPs, we find out a first sign of Osteoblast cells differentiation with bone nodules formation, as confirmed by alkaline phosphatase (ALP) activity assay.


Assuntos
Gelatina/química , Ouro/química , Nanopartículas Metálicas , Osteoblastos/citologia , Humanos , Microscopia Eletrônica de Transmissão , Osteoblastos/ultraestrutura
14.
Colloids Surf B Biointerfaces ; 103: 475-81, 2013 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-23261569

RESUMO

It is well known that standard citrate-reduced gold nanoparticles (AuNPs) are unstable at high ionic strength solution, which limits their applications in the biomedical field. In this work we present an environmentally friendly approach for the stabilization of citrate-reduced AuNPs in aqueous solution. Specifically, the stability of the AuNPs against salt-induced aggregation was greatly improved in the presence of gelatin biopolymer and stabilization of individual or small assemblies of nanoparticles can be controlled by the amount of gelatin. Furthermore, the gelatin-nanogold bioconjugates were demonstrated to be operational as highly sensitive surface-enhanced Raman scattering (SERS) active substrate for the detection of Rose Bengal fluorophore in solution at very low concentration. The results suggest that such bioconjugates can be successfully employed not only for detection of analytes, but more interestingly for building SERS-active tags in view of imaging purpose. The stabilization of bioconjugates was analyzed by localized surface plasmon resonance spectroscopy (LSPR), transmission electron microscopy (TEM), dynamic light scattering (DLS) and zeta-potential, and the chemical interaction of gelatin with AuNPs was inferred from Fourier transform infrared spectroscopy (FT-IR).


Assuntos
Gelatina/química , Ouro/química , Nanopartículas Metálicas/química , Análise Espectral Raman/métodos , Animais , Luz , Nanopartículas Metálicas/ultraestrutura , Espalhamento de Radiação , Espectroscopia de Infravermelho com Transformada de Fourier , Ressonância de Plasmônio de Superfície , Sus scrofa
15.
Artigo em Inglês | MEDLINE | ID: mdl-22885930

RESUMO

Absorption spectra of PTCDI (3,4,9,10-perylene-tetracarboxylic-diimide) have been investigated in chloroform, N,N'-dimethylformamide (DMF) and dimethylsulfoxide (DMSO). While no signature of assembled PTCDI molecules is observed in chloroform solution, distinct bands assigned to their aggregation have been identified in DMF and DMSO solutions. PTCDI monomers show very similar absorption patterns in chloroform and DMSO solutions. Experimental data, including the vibronic structure of the absorption spectra were explained based on the Franck-Condon approximation and quantum chemical results obtained at PBE0-DCP/6-31+G(d,p) level of theory. Geometry optimization of the first excited state leads to a nice agreement between the calculated adiabatic transition energies and experimental data.


Assuntos
Imidas/química , Modelos Moleculares , Perileno/análogos & derivados , Teoria Quântica , Absorção , Clorofórmio/química , Dimerização , Dimetil Sulfóxido/química , Dimetilformamida/química , Gases/química , Conformação Molecular , Perileno/química , Soluções , Espectrometria de Fluorescência , Espectrofotometria Ultravioleta , Fatores de Tempo , Vibração
16.
Nanotechnology ; 20(31): 315602, 2009 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-19597258

RESUMO

In this study we present a clean, nontoxic, environmentally friendly synthesis procedure to generate a large variety of gold nanoparticles (GNPs) by using chitosan, a biocompatible, biodegradable, natural polymer, as reducing and stabilizing agent. The formation of gold-chitosan nanocomposites was characterized by UV-vis absorption spectroscopy, transmission electron microscopy (TEM), x-ray diffraction (XRD) and Raman spectroscopy. The results show that the reaction temperature plays a crucial role in controlling the size, shape and crystalline structure of GNPs. In addition, it is demonstrated that chitosan can perform as a scaffold for the assembly of GNPs, which were successfully applied as substrate for surface-enhanced Raman scattering (SERS). To test the SERS activity, a relevant biological molecule--tryptophan--was adopted as the analyte.


Assuntos
Materiais Biocompatíveis/síntese química , Quitosana/química , Ouro/química , Nanopartículas Metálicas/química , Nanocompostos/química , Materiais Biocompatíveis/química , Colorimetria , Microscopia Eletrônica de Transmissão , Espectrofotometria Ultravioleta , Análise Espectral Raman/métodos , Temperatura , Triptofano/química , Difração de Raios X
17.
Chemphyschem ; 10(7): 1106-11, 2009 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-19322798

RESUMO

Metallic multilayer structures consisting of self-assembled nanoparticles are prepared by successive immersion of a functionalized glass substrate in a gold colloidal suspension, and are characterized by UV/Vis spectroscopy and atomic force microscopy. The ability of the thin film to concomitantly enhance the Raman and IR signals of an adsorbed molecule is evaluated and a detailed analysis of the recorded spectra is provided, which emphasizes the capability of these complementary methods to provide information about the adsorbed species. This unique surface-enhanced Raman spectroscopy (SERS) and surface-enhanced infrared absorption (SEIRA) substrate could be further used for applications in the elucidation of the structure of a great variety of adsorbed samples.


Assuntos
Ouro/química , Membranas Artificiais , Nanopartículas Metálicas/química , Vidro/química , Estrutura Molecular , Tamanho da Partícula , Espectrofotometria Infravermelho/métodos , Análise Espectral Raman/métodos , Propriedades de Superfície
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