Navegando por Palavras-chave "Atomic force microscopy"
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- ItemAcesso aberto (Open Access)Amyloid formation by short peptides in the presence of dipalmitoylphosphatidylcholine membranes(American Chemical Society, 2020-11-19) da Silva, Emerson Rodrigo [UNIFESP]; Gerbelli, Barbara Bianca; Alves, Wendel Andrade; Oliveira, Cristiano Luis Pinto; Hamley, Ian; http://lattes.cnpq.br/7800589206457326The aggregation of two short peptides [RF] and [RF]4 (where R = arginine and F = phenylalanine) with dipalmitoylphosphatidylcholine (DPPC) model membranes was investigated at the air-water interface using the Langmuir technique and vesicles in aqueous solutions. The molar ratio of the peptide and lipid components was varied to provide insights into the peptide-membrane interactions, which might be related to their cytotoxicity.1 Both peptides exhibited affinity to the DPPC membrane interface and rapidly adopted β-sheet rich structures upon adsorption onto the surface of the zwitterionic membrane. Results from adsorption isotherm and small angle X-ray scattering (SAXS) experiments showed changes in the structural and thermodynamics parameters of the membrane with the increase in peptide concentration. Using atomic force microscopy (AFM), we showed the appearance of pores through the bilayer membranes and peptide aggregation at different interfaces, suggesting that the hydrophobic residues might have an effect on both pore size and layer structure, facilitating the membrane disruption and leading to different cytotoxicity effects.
- ItemAcesso aberto (Open Access)Amyloid-like self-assembly of a hydrophobic cell-penetrating peptide and its use as a carrier for nucleic acids(American Chemical Society, 2021-08-04) da Silva, Emerson Rodrigo [UNIFESP]; Mello, Lucas Rodrigues de [UNIFESP]; Porosk, Ly; Lourenço, Thiago da Costa [UNIFESP]; Garcia, Bianca Bonetto Moreno [UNIFESP]; Costa, Carlos Alberto Rodrigues; Han, Sang Won [UNIFESP]; Souza, Juliana dos Santos de; Langel, Ülo; http://lattes.cnpq.br/7800589206457326; http://lattes.cnpq.br/4209242593570615; http://lattes.cnpq.br/4726216622634724; http://lattes.cnpq.br/7341563736516694; http://lattes.cnpq.br/2833950143696339; http://lattes.cnpq.br/0069955147703693; http://lattes.cnpq.br/7929949468269206Cell-penetrating peptides (CPPs) are a topic subject potentially exploitable for creating new nanotherapeutics for the delivery of bioactive loads. These compounds are often classified into three major categories according to their physicochemical characteristics: cationic, amphiphilic, and hydrophobic. Among them, the group of hydrophobic CPPs has received increasing attention in recent years due to toxicity concerns posed by highly cationic CPPs. The hexapeptide PFVYLI (P: proline, F: phenylalanine, V: valine, Y: tyrosine, L: leucine and I: isoleucine), a fragment derived from the C-terminal portion of α1-antitrypsin, is a prototypal example of hydrophobic CPP. This sequence shows reduced cytotoxicity, capacity of nuclear localization, and its small size readily hints suitability as a building block to construct nanostructured materials. In this study, we examine the self-assembling properties of PFVYLI and investigate its ability to form non-covalent complexes with nucleic acids. By using a combination of biophysical tools including synchrotron small-angle X-ray scattering and atomic force microscopy-based infrared spectroscopy, we discovered that this CPP self-assembles into discrete nanofibrils with remarkable amyloidogenic features. Over the course of days, these fibrils coalesce into rod-like crystals that easily reach the micrometer range. Despite lacking cationic residues in the composition, PFVYLI forms non-covalent complexes with nucleic acids that retain -sheet pairing found in amyloid aggregates. In vitro vectorization experiments performed with double-stranded DNA fragments indicate that complexes promote the internalization of nucleic acids, revealing that tropism toward cell membranes is preserved upon complexation. On the other hand, transfection assays with splice-correction oligonucleotides (SCOs) for luciferase expression show limited bioactivity across a narrow concentration window, suggesting that propensity to form amyloidogenic aggregates may trigger endosomal entrapment. We anticipate that the findings presented here open perspectives for using this archetypical hydrophobic CPP in the fabrication of nanostructured scaffolds, which potentially integrate properties of amyloids and translocation capabilities of CPPs.
- ItemAcesso aberto (Open Access)Estudo de biocompatibilidade do titânio recoberto com nanofilmes de carbono e prata(Universidade Federal de São Paulo (UNIFESP), 2018-07-26) Placias, Flavio Gomes [UNIFESP]; Koh, Ivan Hong Jun [UNIFESP]; Matieli, José Elias; http://lattes.cnpq.br/0350866868370257; http://lattes.cnpq.br/6695612966568322; Universidade Federal de São Paulo (UNIFESP)Introduction: The main barriers to new prosthetic materials are rejection and infection associated with the implant. Among the materials, titanium (Ti) substrate has been widely used due to its biocompatibility and mechanical properties. However, its biocompatibility and biointegration have been questioned in the literature. Objectives: The present study aimed to improve the biocompatibility and biointegration of Ti by coating its surface with carbon nanofilm Diamondlike Carbon (DLC) and to promote microbicide capacity with silver (Ag) nanoparticles. Methods: Coatings were performed with Plasma Technology. PlasmaEnhanced Chemical Vapor Deposition (PECVD) was the method used to apply the nanofilms coatings on Ti plates. The physical characterization of the plate surface was performed by Atomic Force Microscopy (AFM) and the microbicide capacity was analyzed by culture. The biocompatibility and biointegration were studied in rats (WistarEPM, n = 24) that received the implant of the plates in the abdominal wall. Animals were reoperated after 7, 28, 90 and 180 days. Tissue integration by AMF, histology and macroscopy were monitorized.Results: The AMF presented plates surfaces modifications after nanocoating. None of the coating groups demonstrated microbicide activity. The macroscopy showed tissue adhesion and no signs of rejection. This adhesion was confirmed by the AMF. The histology showed signs of chronic inflammation that did not prevent biointegration. Conclusions: The results showed that the nanocoating enabled the implanthost interaction, but did not alter the Ti biocompatibility. In addition, the Ag deposition, under the determinated conditions, did not demonstrated the expected antimicrobial effect.
- ItemAcesso aberto (Open Access)Modification of the linker amino acid in the cell-penetrating peptide NickFect55 leads to enhanced pDNA transfection for in vivo applications(MDPI, 2023-02-20) Porosk, Ly; Mello, Lucas; da Silva, Emerson Rodrigo [UNIFESP]; Härk, Heleri; Kurrikoff, Kaido; Arukuust, Piret; http://lattes.cnpq.br/7800589206457326Despite numerous efforts over the last three decades, nucleic acid-based therapeutics still lack delivery platforms in the clinical stage. Cell-penetrating peptides (CPPs) may offer solutions as potential delivery vectors. We have previously shown that designing a “kinked” structure in the peptide backbone resulted in a CPP with efficient in vitro transfection properties. Further optimization of the charge distribution in the C-terminal part of the peptide led to potent in vivo activity with the resultant CPP NickFect55 (NF55). Currently, the impact of the linker amino acid was further investigated in the CPP NF55, with the aim to discover potential transfection reagents for in vivo application. Taking into account the expression of the delivered reporter in the lung tissue of mice, and the cell transfection in the human lung adenocarcinoma cell line, the new peptides NF55-Dap and NF55-Dab* have a high potential for delivering nucleic acid-based therapeutics to treat lung associated diseases, such as adenocarcinoma.