71 research outputs found
Polymer functionalized gold nanoparticles as non-viral gene delivery reagents.
Background: In this study we investigated the ability of PEG functionalized gold nanoparticles
as non-viral vectors in the transfection of different cell lines, comparing them with commercial
lipoplexes.
Methods: Positively charged gold nanoparticles were synthesized using PEI as reducing and
stabilizer agent and its cytotoxicity reduced by its functionalization with PEG. We bound the
nanoparticles to three plasmids with different sizes (4-40 kpb). The vector internalization was
evaluated by confocal and electronic microscopy. Its transfection efficacy was studied by
fluorescence microscopy and flow cytometry. The application of the resulting vector in gene
therapy was indirectly evaluated using ganciclovir in HeLa cells transfected to express the
herpes virus thymidine kinase.
Results: An appropriate ratio between the nitrogen from the PEI and the phosphorous from
the phosphate groups of the DNA together with a reduced size and an elevated electrokinetic
potential are responsible for an increased nanoparticle internalization and enhanced protein
expression when carrying plasmids of up to 40kbp (plasmid size close to the limit of the DNA
carrying capacity of viral vectors). Compared to a commercial transfection reagent, an equal or
even higher expression of reporter genes (on HeLa and HEK 293T) and suicide effect on HeLa
cells transfected with the herpes virus thymidine kinase gene were observed when using this
novel nanoparticulated vector.
Conclusions: Non-viral vectors based on gold nanoparticles covalently coupled with
polyethylene glycol (PEG) and Polyethylenimine (PEI) can be used as efficient transfection
reagents showing expression levels same or greater than the ones obtained with commercially
available lipoplexes.pre-print3905 K
Microwave-Driven Exfoliation of Bulk 2H-MoS<sub>2</sub> after Acetonitrile Prewetting Produces Large-Area Ultrathin Flakes with Exceptionally High Yield
2D materials display exciting properties in numerous fields, but the development of applications is hindered by the low yields, high processing times, and impaired quality of current exfoliation methods. In this work we have used the excellent MW absorption properties of MoS2 to induce a fast heating that produces the near-instantaneous evaporation of an adsorbed, low boiling point solvent. The sudden evaporation creates an internal pressure that separates the MoS2 layers with high efficiency, and these are kept separated by the action of the dispersion solvent. Our fast method (90 s) gives high yields (47% at 0.2 mg/mL, 35% at 1 mg/mL) of highly exfoliated material (90% under 4 layers), large area (up to several μm2), and excellent quality (no significant MoO3 detected)
Rheology and Tack Properties of Biodegradable Isodimorphic Poly(butylene succinate)-Ran-Poly(ε-caprolactone) Random Copolyesters and Their Potential Use as Adhesives
The sole effect of the microstructure of biodegradable isodimorphic poly(butylene succinate)-ran-poly(ε-caprolactone) random copolyesters on their rheological properties is investigated. To avoid the effect of molecular weight and temperature, two rheological procedures are considered: the activation energy of flow, Ea, and the phase angle versus complex modulus plots. An unexpected variation of both parameters with copolyester composition is observed, with respective maximum and minimum values for the 50/50 composition. This might be due to the peculiar chain configurations of the copolymers that vary as a function of comonomer distribution within the chains. The same chain configuration variations are responsible for the isodimorphic character of the copolymers in the crystalline state. Tack tests, performed to study the viability of the copolyesters as environmentally friendly hot melt adhesives (HMA), reveal a correlation with rheological results. Tackiness parameters, particularly the energy of adhesion obtained from stress-strain curves during debonding experiments, are enhanced as melt elasticity increases. Based on the carried-out analysis, the link microstructure-rheology-tackiness is established, allowing selecting the best performing HMA sample considering the polymer chemistry of the system.We acknowledge the financial support from the BIODEST project; this project has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie Grant Agreement No. 778092. This work has also received funding from the Basque Government through grant IT1309-19
Thermo-rheological effects on succesful 3D printing of biodegradable polyesters
Unformatted preprint version of the submitted articleBiodegradable polybutylene succinate (PBS) and poly (butylene succinate-ran-adipate) (PBSA) were characterized to find the thermo-rheological bases for 3D printing by Fused Filament Fabrication (FFF). In dynamic viscoelastic measurements, the samples fulfilled time-temperature superposition and Cox Merz rule. The viscosity results were linked to the excellent filaments obtained and the observed good flow in the printer nozzle. Using specific tearing experiments, outstanding welding of the printed layers was obtained. Results were discussed considering the values of the entanglements density obtained by SAOS measurements. The main difference between both polymers was observed in the final production of 3D printed parts because the high crystallinity of PBS produced significant warpage, which prevented its use for practical purposes. On the contrary, the less crystalline PBSA random copolymer showed excellent performance during FFF. Thus, dimensionally stable and ductile printed objects were obtained, opening new processing routes for semi-crystalline biodegradable polyesters.This work has received funding from the European Union´s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No 778092, from MINECO, project: MAT2017-83014-C2-1-P and from the Basque Government through grant IT1309-19
The effect of hollow gold nanoparticles on stem cell migration. Potencial application in tissue regeneration.
Every year trauma together with bone, joints and cartilage-associated diseases
usually involve structural damage, resulting in a severe pain and disability for millions of
people worldwide[1]. In regenerative medicine, cellular, tissue and organ-based approaches
are developed to restore biological functions that have been lost[2],[3]. Therefore, tissue
repair and regenerative medicine have attracted the interest of the scientific community,
providing promising results in preclinical models and clinical pilot studies.pre-print3341 K
Extracellular vesicles from induced neurons trigger epigenetic silencing of a brain neurotransmitter.
Introduction: Antithrombin (AT) is a glycoprotein involved in the regulation of blood coagulation. It belongs to the family of serine-protease inhibitors and acts as the most important antagonist of different clot- ting factors. Two types of inherited AT deficiency can be distinguished: Type I (quantitative deficit), and Type II (qualitative deficit). The latter is characterized by an impaired inhibitory activity related to dysfunc- tional domains of the protein. Three Type II subtypes can be defined: Type IIa (reactive site defect), Type IIb (heparin binding site defect) and Type IIc (pleiotropic defect). This classification has clinical importance since these subtypes have a different thrombotic risk. No functional routine diagnostic assay, however, can be assumed to detect all forms of Type II deficiencies since false-negative results may hamper the diagnosis. Methods: We analysed the biochemical/biophysical association of ATT to EVs. We separated EVs from plasma of healthy or Type II affected patients or from cultured hepatocytes through differential ultracentrifu- gation followed by sucrose density gradient and/or immunoprecipitation. We next combined dot blot ana- lysis, WB, 2D electrophoresis and enzymatic assays to reveal the nature of ATT association to EVs.
Results: We evidenced that ATT is associated to the external leaflet of EVs. We also found that specific ATT isoforms are enriched in EV preparations in respect to total plasma and that those isoforms are selectively associated to EVs when comparing healthy or ATT type II deficient patients.
Summary/Conclusion: ATT selective association pat- tern to EVs might be related either to mutations in the primary sequence of the protein or alterations in the glycosylation process, hence experiments are ongoing to reveal the nature of this phenomenon. Our findings suggest that analysis of ATT enriched in EV prepara- tions might be useful to gain insights into the patho- genesis and be of support in the diagnostic algorithm of ATT deficiency.
Funding: This work acknowledges FFABR (Fondo finanziamento attività Base di ricerca from MIUR, Ministry of Education, Universities and Research, Italy) for financial support
Selective delivery of photothermal nanoparticles to tumors using mesenchymal stem cells as Trojan horses
The main challenge of cancer treatment is to avoid or minimize systemic side effects in off-target tissues. Mesenchymal stem cells (MSCs) can be used as therapeutical carriers because of their ability to migrate and incorporate into inflammation areas including tumors. Here, this homing ability is exploited by carrying therapeutic nanoparticles (Hollow Gold Nanoparticles (HGNs)) following a “Trojan-horse” strategy. Amongst the different nanoparticles to be employed, HGNs have the capacity to resonate in the near infrared region when irradiated by an appropriated laser (808 nm). By transforming this absorbed energy into heat, they are capable to produce locally induced hyperthermia. At this wavelength healthy tissues have a minimal light absorption being the effect restricted to the tissues containing HGNs. By placing HGNs inside MSCs, the recognition, excretion and immune response are minimized. We demonstrate that MSCs internalize HGNs and reach the tumors still containing HGNs. After laser treatment this loaded cells are able to eradicate tumoral cells in vitro and in vivo without significant toxicity. Also Ki67 expression, which is usually correlated with proliferation, is reduced after treatment. This approach enhances the effectiveness of the treatment when compared to just the enhanced permeation and retention effect (EPR) of the HGNs by themselves
Efficient encapsulation of theranostic nanoparticles in cell-derived exosomes: leveraging the exosomal biogenesis pathway to obtain hollow gold nanoparticle-hybrids
Exosomes can be considered natural targeted delivery systems able to carry exogenous payloads, drugs or theranostic nanoparticles (NPs). This work aims to combine the therapeutic capabilities of hollow gold nanoparticles (HGNs) with the unique tumor targeting properties provided by exosomes. Here, we tested different methods to encapsulate HGNs (capable of absorbing light in the NIR region for selective thermal ablation) into murine melanoma cells derived exosomes (B16-F10-exos), including electroporation, passive loading by diffusion, thermal shock, sonication and saponin-assisted loading. These methods gave less than satisfactory results: although internalization of relatively large NPs into B16-F10-exos was achieved by almost all the physicochemical methods tested, only about 15% of the exosomes were loaded with NPs and several of those processes had a negative effect regarding the morphology and integrity of the loaded exosomes. In a different approach, B16-F10 cells were pre-incubated with PEGylated HGNs (PEG-HGNs) in an attempt to incorporate the NPs into the exosomal biogenesis pathway. The results were highly successful: exosomes recovered from the supernatant of the cell culture showed up to 50% of HGNs internalization. The obtained hybrid HGN-exosome vectors were characterized with a battery of techniques to make sure that internalization of HGNs did not affect exosome characteristics compared with other strategies. PEG-HGNs were released through the endosomal-exosome biogenesis pathway confirming that the isolated vesicles were exosomes
Study of the interlayer adhesion and warping during material extrusion-based additive manufacturing of a carbon nanotube/biobased thermoplastic polyurethane nanocomposite
Unformatted preprint version of the submitted articleA thermoplastic bio-polyurethane from renewable sources (TPU) and the nanocomposite developed by mixing it
with carbon nanotubes (CNT) are investigated as potentially adequate for Material Extrusion-based Additive
Manufacturing (EAM). Thermal and rheological features are studied from the perspective of their liaisons with
printing adequacy and conditions. As predicted by rheology, both samples show good performance in filament
elaboration and flow in the nozzle. Warpage is observed for TPU, but not for the nanocomposite, which is due to
the effect of CNT nanoparticles on polymer chains dynamics. At the studied printing velocities, interlayer
adhesion strength is independent of printing velocity implying that there is no significant chain orientation
which can induce changes in the TPU entanglements. The nanocomposite shows a lower welding strength,
notwithstanding both have the same chain entanglements density. This is explained by considering that the
higher viscosity of TPU/CNT, as compared to TPU, reduces the melt diffusion coefficient.We would like to thank the financial support provided by the BIODEST project. This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 778092. This work has also received funding from MINECO through project MAT2017-83014-C2-1-P and from the Basque Government through grant IT1309-19
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