Navegando por Palavras-chave "Gold Nanoparticles"
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- ItemSomente MetadadadosAumento De Sensibilidade De Sensor De Ressonância Plasmônica De Superfície Para Detecção De Proteínas(Universidade Federal de São Paulo (UNIFESP), 2017-02-10) Macedo, Erenildo Ferreira De [UNIFESP]; Tada, Dayane Batista [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)This study describes the development of a method to increase the sensitivity of a Surface Plasmon Resonance Biosensor (SPR) to detect proteins at low concentrations. The method used gold nanoparticles (AuNPs) in two different approaches. In the first one, the protein to be detected was covalently linked to the AuNPs and then analyzed on the SPR sensor. In the second approach AuNPs were functionalized with specific antibody to capture protein of interest free in solution. The chosen proteins were lectins Arachis hypogaea (PNA) and Canavalia ensiformis (conA), and the biomarker of ovarian cancer, mesothelin. The second approach was more efficient in amplifying the signal, providing a better resolution response and reduced detection limit. The sensor response was compared to the detection of free protein in solution and the detection of protein covalently linked to AuNPs. In this order, the limit of detection for the approach of using the AuNPs to capture proteins was 98% and 89% lower in PNA detection and 79% and 77% lower in conA detection. It is possible that the higher efficiency was due to the role of AuNPs in enhancing the concentration of protein at NPs surface, as well as in providing the plasmonic coupling between the AuNPs and the gold surface of the SPR sensor. This result motivated the use of capture AuNPs in the detection of the protein mesothelin, an important biomarker used in the diagnosis of ovarian cancer and mesothelioma. The test was performed based on the cutoff point used to diagnose ovarian cancer (415pM). The result showed a detection limit of 35pM, which was of great relevance, demonstrating the efficiency of detection of mesothelin at low concentrations, demonstrating the potential use of this method for future studies in the area of cancer diagnosis.
- ItemSomente MetadadadosDevelopment of silver nanoparticles-based sensor for detection of quinolones by surface-enhanced raman spectroscopy: a case-study using levofloxacin(Wiley, 2016) Madalossi, Natiara V.; Mazali, Italo O.; Corbi, Fabiana C. A.; Sigoli, Fernando A.; Santos, Elias B. [UNIFESP]Numerous studies have shown that a variety of pharmaceuticals such as quinolones have been detected in the vicinity of municipal wastewater discharges and livestock agricultural facilities. Many of those works have been employed conventional analytical techniques and traditional methods of detection. However, in many cases these detection methodologies are time consuming and generate waste, which can be overcome using Surface-enhanced Raman spectroscopy (SERS) as analytical technique. In the present work, silver nanoparticles (AgNP) films were prepared on amine-modified glass slides with different number of depositions. The AgNP aggregates films were tested as SERS substrates using 4-aminobenzenethiol (4-ABT) as model Raman molecule. A trend between the 4-ABT SERS response and the number of AgNP deposition could be identified, which can be associated with the formation of AgNP aggregates. The aggregation effect could be quantified by calculating the enhancement factor (EF), which was on order of 10(6) for the film with five AgNP depositions. This optimized AgNP film was employed as SERS sensor of Levofloxacin in different concentrations, which was easily detected from 10(-4), 10(-5), and 10(-6) mol L-1 solution. Also, the SERS spectral profile are rich in information, which allowed to describe the chemical interaction between the Levofloxacin molecules and the AgNP sensor surface. This study provides an efficient method for detecting of Levofloxacin using AgNP SERS sensor, which can be extended for others quinolones.
- ItemSomente MetadadadosFuncionalização De Nanopartículas Metálicas Com Diferentes Combinações De Peptídeos Para Aplicações Como Agentes Antimicrobianos E Antitumorais(Universidade Federal de São Paulo (UNIFESP), 2017-11-27) Formaggio, Daniela Maria Ducatti [UNIFESP]; Tada, Dayane Batista [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)Metal nanoparticles (NPs) have showing promising applications in the biomedical field. These NPs have unique physicochemical properties, as well as great chemical versatility on their surface, which allows new modifications and incorporations of different molecules. In addition, they have the advantage of accumulating preferentially in tumor tissues due to the enhanced permeability and retention effect, known as EPR. The incorporation of therapeutic peptides to the surface of metallic NPs could be a promising strategy to improve their applications as therapeutic molecules. Peptides are highly selective molecules. However, they are also vulnerable to some in vivo pharmacologic barriers limiting their effective action, including low bioavailability or deactivation by enzymes. In this work, three types of metal NPs were prepared: gold NPs (AuNPs), silver NPs (AgNPs) and bimetallic NPs composed by gold and platinum (AuPtNPs). NPs were characterized by ultraviolet-visible spectroscopy (UV-Vis), dynamic light scattering (DLS), transmission electron microscopy (TEM), inductively coupled plasma optical emission spectroscopy (ICP-OES) and X-ray diffraction (XRD). Aiming at biomedical applications, NPs were firstly evaluated regarding their toxicity by cell viability assays using human fibroblast cells (HS68 cell line) and embryonic toxicity test in zebrafish (Danio rerio). The assays showed better biocompatibility of AuNPs compared to AgNPs and AuPtNPs. Thus, AuNPs were studied as carriers of antitumor and antimicrobial peptides as an alternative approach of overcoming the pharmacokinetic limitations inherent in these molecules. Two peptides derived from complementary monoclonal antibodies (CDRs) with amino acid sequences YISCYNGATSYNQKFK (C7H2) and RASQSVSSYLA (HuAL1) were previously identified by collaborators of this project demonstrating excellent toxicity against tumor cells, antimetastatic activity as well as a potent antimicrobial activity. The peptides were individually conjugated to the AuNPs surface, forming the AuNPsC7H2 and AuNPsHuAL1 NPs. The peptides were also linked together forming the AuNPsC7H2HuAL1. The in vitro results suggested an improved antitumor activity for AuNPsHuAL1 and AuNPsC7H2HuAL1 against metastatic melanoma tumor cell line (B16F10-Nex2) compared to the peptides in solution. In vivo, the peptide combination of HuAL1 and C7H2 was even more efficient when linked to AuNPs. The antimicrobial activity of the three NPs separately as well as the peptide functionalized AuNPs were also evaluated employing microdilution test against strains of Candida Albicans, Pseudomonas aeruginosa and Staphylococcus aureus. The results confirm an intrinsic antimicrobial action of the three metal NPs and an optimal antibiotic action for AuNPsHuAL1.
- ItemSomente MetadadadosNanopartículas de ouro em líquidos iônicos: preparação, caracterização e imobilização em celulose não modificada(Universidade Federal de São Paulo (UNIFESP), 2021) Cabreira, Camila Rodrigues [UNIFESP]; Camilo, Fernanda Ferraz [UNIFESP]; Universidade Federal de São PauloGold nanoparticles (AuNPs) are attractive due to their interesting properties and applications such as therapeutic agents, sensors and catalysts. In view of these numerous applications, this thesis focused on the synthesis of AuNPs in ionic liquids (ILs), and their use in two different areas. The first goal was the study of the effects of AuNPs on cell membrane models, due to its application in medicine. The second aim was to immobilize AuNPs on cellulose and evaluate the catalytic activity of the material in the reduction of 4-nitrophenol. Thus, in this thesis AuNPs were prepared by Au3+ reduction using tetrabutylammonium borohydride (TBABH4) in different ILs containing imidazolium cations, such as 1-butyl-3- methylimidazolium (BMIm) or 1-octyl-3-methylimidazolium (OMIm) or 1-dodecyl-3- methylimidazolium (DMIm) chloride (Cl- ) and bis(trifluoromethanesulfonyl)imide (Tf2N- ). Dispersions of AuNPs at 3 mM, 10 mM and 20 mM concentrations were obtained in 1-butyl-3-methylimidazolium chloride (BMImCl) and 1-octyl-3-methylimidazolium chloride (OMImCl), and showed good stability over time. The dispersions contain nanoparticles with diameters around 5-20 nm. Increasing the alkyl chain length of the imidazolium cation from butyl to octyl led to the formation of smaller and more monodisperse AuNPs. Due to its high viscosity, AuNPs synthesis using 1-dodecyl-3- methylimidazolium chloride (DMImCl) was not performed. Also, stable dispersions were not obtained in ionic liquids containing Tf2Nanion. AuNPs synthesized in ILs and pure ILs were incorporated in monolayers of dipalmitoylphosphatidylcholine (DPPC) at the air-water interface as cell membrane model in a Langmuir trough. All the samples led to monolayer condensation and presented a homogeneous pattern, suggesting that both pure ILs and AuNPs in ionic liquids interact with the cell membrane model. A film of cellulose containing AuNPs synthesized in aqueous media was prepared efficiently by impregnation of an aqueous AuNPs dispersion in a regenerated cellulose film. It has cellulose type II structure and nanoparticles around 10 nm are homogeneously dispersed along the polymeric matrix. Cellulose films containing AuNPs prepared in BMImCl and OMImCl were also obtained by a simpler methodology than the one using AuNPs in aqueous medium. This method allowed the incorporation of higher concentrations of Au into the films. They have cellulose type II and spherical nanoparticles well distributed along the films. The films of cellulose and AuNPs were applied as heterogeneous catalysts for 4-nitrophenol reduction. The film containing AuNPs prepared in water showed great efficiency during 5 cycles. Films containing AuNPs prepared in ionic liquids were efficient for around 8 cycles, and the catalysts containing AuNPs in OMImCl showed the highest kapp values. The ease of removal of the films from the reaction medium makes the hybrid material very appealing in application as a catalyst.
- ItemSomente MetadadadosPhytofabricated metallic nanoparticles and their clinical applications(Dove Medical Press Ltd, 2016) Baranwal, Anupriya; Mahato, Kuldeep; Srivastava, Ananya; Maurya, Pawan Kumar [UNIFESP]; Chandra, PranjalMetallic nanoparticles (MNPs) have seen myriad applications in various fields of science and technology. Green chemistry based NP synthesis offers several advantages over conventional approaches. In addition to being inexpensive, the biological approach is a facile, rapid, and environmentally benign method to synthesize NPs. Characterization of NPs is generally based on their dimension, surface area, and dispersity and the most common techniques used for the purpose are UV-Vis, DLS, AFM, SEM, FTIR, XRD, TEM, Raman spectroscopy, etc. These techniques are considered very useful as they provide valuable information which helps these materials to be used for diverse biological and environmental applications. Until now, numerous plant sources have been utilized to generate copious MNPs, such as silver, gold, copper, titanium, platinum, palladium, zinc, and iron NP. Among these MNPs, the noble ones have attracted significant researchers' attention because they are non-corrosive and resistant to oxidation in moist air. They have been useful in providing remedies with less or no adverse effects for several acute diseases like cancer, malaria, HIV, and hepatitis. Herein, we present a systematic review, focusing on phytofabricated MNPs and their wide range of applications, such as sensors, diagnostics and therapeutics, antimicrobial agents, anti-inflammatory agents, cancer treatment, etc.
- ItemSomente MetadadadosUsing femtosecond lasers to modify sizes of gold nanoparticles(Spie-int soc optical engineering, 2016) Cordeiro, Thiago da Silva; de Matos, Ricardo Almeida [UNIFESP]; de Oliveira Silva, Flavia Rodrigues; Vieira, Nilson Dias, Jr.; Courrol, Lilia Coronato [UNIFESP]; Samad, Ricardo ElgulMetallic nanoparticles are important on several scientific, medical and industrial areas. The control of nanoparticles characteristics has fundamental importance to increase the efficiency on the processes and applications in which they are employed. The metallic nanoparticles present specific surface plasmon resonances (SPR). These resonances are related with the collective oscillations of the electrons presents on the metallic nanoparticle. The SPR is determined by the potential defined by the nanoparticle size and geometry. There are several methods of producing gold nanoparticles, including the use of toxic chemical polymers. We already reported the use of natural polymers, as for example, the agar-agar, to produce metallic nanoparticles under xenon lamp irradiation. This technique is characterized as a "green" synthesis because the natural polymers are inoffensive to the environment. We report a technique to produce metallic nanoparticles and change its geometrical and dimensional characteristics using a femtosecond laser. The 1 ml initial solution was irradiate using a laser beam with 380 mW, 1 kHz and 40 nm of bandwidth centered at 800 nm. The setup uses an Acousto-optic modulator, Dazzler, to change the pulses spectral profiles by introduction of several orders of phase, resulting in different temporal energy distributions. The use of Dazzler has the objective of change the gold nanoparticles average size by the changing of temporal energy distributions of the laser pulses incident in the sample. After the laser irradiation, the gold nanoparticles average diameter were less than 15 nm.