Luiz O. Ladeira

Highly efficient siRNA delivery system into human and murine cells using single-wall carbon nanotubes

Development of RNA interference (RNAi) technology utilizing short interfering RNA sequences (siRNA) has focused on creating methods for delivering siRNAs to cells and for enhancing siRNA stability in vitro and in vivo. Here, we describe a novel approach for siRNA cellular delivery using siRNA coiling into carboxyl-functionalized single-wall carbon nanotubes (SWCNTs). The CNT-siRNA delivery system successfully demonstrates nonspecific toxicity and transfection efficiency greater than 95%. This approach offers the potential for siRNA delivery into different types of cells, including hard-to-transfect cells, such as neuronal cells and cardiomyocytes. We also tested the CNT-siRNA system in a non-metastatic human hepatocellular carcinoma cell line (SKHep1). In all types of cells used in this work the CNT-siRNA delivery system showed high efficiency and apparent no side effects for various in vitro applications.

Carbon nanotube interaction with extracellular matrix proteins producing scaffolds for tissue engineering

In recent years, significant progress has been made in organ transplantation, surgical reconstruction, and the use of artificial prostheses to treat the loss or failure of an organ or bone tissue. In recent years, considerable attention has been given to carbon nanotubes and collagen composite materials and their applications in the field of tissue engineering due to their minimal foreign-body reactions, an intrinsic antibacterial nature, biocompatibility, biodegradability, and the ability to be molded into various geometries and forms such as porous structures, suitable for cell ingrowth, proliferation, and differentiation. Recently, grafted collagen and some other natural and synthetic polymers with carbon nanotubes have been incorporated to increase the mechanical strength of these composites. Carbon nanotube composites are thus emerging as potential materials for artificial bone and bone regeneration in tissue engineering.

Influence of spontaneous calcium events on cell-cycle progression in embryonal carcinoma and adult stem cells

Spontaneous Ca(2+) events have been observed in diverse stem cell lines, including carcinoma and mesenchymal stem cells. Interestingly, during cell cycle progression, cells exhibit Ca(2+) transients during the G(1) to S transition, suggesting that these oscillations may play a role in cell cycle progression. We aimed to study the influence of promoting and blocking calcium oscillations in cell proliferation and cell cycle progression, both in neural progenitor and undifferentiated cells. We also identified which calcium stores are required for maintaining these oscillations. Both in neural progenitor and undifferentiated cells calcium oscillations were restricted to the G1/S transition, suggesting a role for these events in progression of the cell cycle. Maintenance of the oscillations required calcium influx only through inositol 1,4,5-triphosphate receptors (IP(3)Rs) and L-type channels in undifferentiated cells, while neural progenitor cells also utilized ryanodine-sensitive stores. Interestingly, promoting calcium oscillations through IP(3)R agonists increased both proliferation and levels of cell cycle regulators such as cyclins A and E. Conversely, blocking calcium events with IP(3)R antagonists had the opposite effect in both undifferentiated and neural progenitor cells. This suggests that calcium events created by IP(3)Rs may be involved in cell cycle progression and proliferation, possibly due to regulation of cyclin levels, both in undifferentiated cells and in neural progenitor cells.

Graphene-based nanomaterials: biological and medical applications and toxicity

Graphene and its derivatives, due to a wide range of unique properties that they possess, can be used as starting material for the synthesis of useful nanocomplexes for innovative therapeutic strategies and biodiagnostics. Here, we summarize the latest progress in graphene and its derivatives and their potential applications for drug delivery, gene delivery, biosensor and tissue engineering. A simple comparison with carbon nanotubes uses in biomedicine is also presented. We also discuss their in vitro and in vivo toxicity and biocompatibility in three different life kingdoms (bacterial, mammalian and plant cells). All aspects of how graphene is internalized after in vivo administration or in vitro cell exposure were brought about, and explain how blood-brain barrier can be overlapped by graphene nanomaterials.

XPS AND EELS STUDY OF THE BISMUTH SELENIDE

Abstract A Bi 2 Se 3 crystal was studied by XPS (X-Ray Photoelectron Spectroscopy) and EELS (Electron Energy Loss Spectroscopy). Al Kα radiation and an electron beam energy in the range of 0.1 to 2 keV were used, respectively, to probe a Se-terminated (0001) surface. Samples of the constituent elements (Bi and Se) have also been measured with the same setup. The core level chemical shifts obtained show that a charge transfer occurs in Bi 2 Se 3 . The spectra in the valence band region suggest that the density of states in the compound may be obtained by combining the spectra of the constituent elements, that the electronic states in the vicinity of the gap region consist of a mixture of the metal and calcogen p -orbitals and that the band arising from the valence s -orbitals occurs about 12 eV below the valence band maximum. The EELS spectra allow to identify the bulk plasmons for the three materials and the Bi5 d 3 and Bi5 d 5 interband transitions. Considerations of the energies of the Bi5 d transitions as measured by XPS and EELS indicate that the bottom of the conduction band of the compound is 1.2 eV above the Fermi level. The EELS results also shows evidence that the losses occurring at 6.4 eV in the compound and at 5.4(5.5) eV in Bi(Se) have their origins in some surface process. We suggest that they may be associated to a surface plasmon.

Nafion–Titanate Nanotube Composite Membranes for PEMFC Operating at High Temperature

Nafion-titanate nanotube composites were investigated as electrolytes for proton exchange membrane fuel cells (PEMFCs) operating at high temperature T. With the addition of 5-15 wt % of nanotubes to the ionomer, PEMFC performance can be significantly sustained for T up to 130°C. The polarization curves of PEMFCs using the composite electrolytes reflect a competing effect between an increase in water uptake due to the extremely large surface area of the nanotubes and a decrease in proton conductivity of the composites.

Oxidized Multiwalled Carbon Nanotubes as Antigen Delivery System to Promote Superior CD8+ T Cell Response and Protection against Cancer

Properties like high interfacial area with cellular membranes, unique ability to incorporate multiple functionalization, as well as compatibility and transport in biological fluids make carbon nanotubes (CNTs) useful for a variety of therapeutic and drug-delivery applications. Here we used a totally synthetic hybrid supramolecule as an anticancer vaccine formulation. This complex structure comprises CNTs as delivery system for the Cancer Testis Antigen named NY-ESO-1, allied to a synthetic Toll-Like Receptor agonist. The CNT constructs were rapidly internalized into dendritic cells, both in vitro and in vivo, and served as an intracellular antigen depot. This property favored the induction of strong CD4(+) T as well as CD8(+) T cell-mediated immune responses against the NY-ESO-1. Importantly, the vaccination significantly delayed the tumor development and prolonged the mice survival, highlighting the potential application of CNTs as a vaccine delivery system to provide superior immunogenicity and strong protection against cancer.

Ecotoxicological effects of carbon nanotubes and cellulose nanofibers in Chlorella vulgaris.

BackgroundMWCNT and CNF are interesting NPs that possess great potential for applications in various fields such as water treatment, reinforcement materials and medical devices. However, the rapid dissemination of NPs can impact the environment and in the human health. Thus, the aim of this study was to evaluate the MWCNT and cotton CNF toxicological effects on freshwater green microalgae Chlorella vulgaris.ResultsExposure to MWCNT and cotton CNF led to reductions on algal growth and cell viability. NP exposure induced reactive oxygen species (ROS) production and a decreased of intracellular ATP levels. Addition of NPs further induced ultrastructural cell damage. MWCNTs penetrate the cell membrane and individual MWCNTs are seen in the cytoplasm while no evidence of cotton CNFs was found inside the cells. Cellular uptake of MWCNT was observed in algae cells cultured in BB medium, but cells cultured in Seine river water did not internalize MWCNTs.ConclusionsUnder the conditions tested, such results confirmed that exposure to MWCNTs and to cotton CNFs affects cell viability and algal growth.

Effects of single wall carbon nanotubes and its functionalization with sodium hyaluronate on bone repair

AIMS Sodium hyaluronate (HY) accelerates the repair of bone defects. However, the weak stability of HY formulations in aqueous environments has hindered its wide utilization. The functionalization of carbon nanotubes (SWCNT) with HY (HY-SWCNT) results in a reinforced hydrogel with an increased stability. Nevertheless, the biological effects of HY-SWCNT have not been explored. Thus, our objective was to evaluate whether this biomaterial preserves the bioactivity of the HY. MAIN METHODS Wistar rats were subjected to molar extraction and the sockets were treated with SWCNT (50-400 microg/mL), 1% HY, HY-SWCNT (50-400 microg/mL) or carbopol (vehicle). After seven days of surgery, histological and morphometric analyses were performed to evaluate the trabecular bone formation and the number of cell nuclei in the sockets. Expression of collagen types I and III was determined by immunohistochemistry. KEY FINDINGS Treatment with SWCNT did not alter the bone deposition, as well as the cell nuclei counting. Additionally, no significant evidence of toxicity was observed in SWCNT-treated sockets. Contrastingly, both HY and HY-SWCNT induced a marked increase in the bone formation (HY: 10.10+/-1.99%; HY-SWCNT 100 microg/mL: 10.90+/-1.13%; control: 3.69+/-1.17%) and decreased the cell nuclei amount in the sockets. Moreover, collagen type I expression was more pronounced in HY- and HY-SWCNT-treated sockets. No significant differences were viewed in the expression of collagen type III. SIGNIFICANCE Our results indicate that SWCNT is a feasible material to deliver HY to bone defects. Importantly, the functionalization of SWCNT with HY preserved the beneficial biological properties of HY in the healing process, thereby suggesting that HY-SWCNT scaffolds are potentially useful biomaterials for the restoration of bone defects.

Succinate causes pathological cardiomyocyte hypertrophy through GPR91 activation

BackgroundSuccinate is an intermediate of the citric acid cycle as well as an extracellular circulating molecule, whose receptor, G protein-coupled receptor-91 (GPR91), was recently identified and characterized in several tissues, including heart. Because some pathological conditions such as ischemia increase succinate blood levels, we investigated the role of this metabolite during a heart ischemic event, using human and rodent models.ResultsWe found that succinate causes cardiac hypertrophy in a GPR91 dependent manner. GPR91 activation triggers the phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2), the expression of calcium/calmodulin dependent protein kinase IIδ (CaMKIIδ) and the translocation of histone deacetylase 5 (HDAC5) into the cytoplasm, which are hypertrophic-signaling events. Furthermore, we found that serum levels of succinate are increased in patients with cardiac hypertrophy associated with acute and chronic ischemic diseases.ConclusionsThese results show for the first time that succinate plays an important role in cardiomyocyte hypertrophy through GPR91 activation, and extend our understanding of how ischemia can induce hypertrophic cardiomyopathy.