Mar Collado-González

Aggregation behaviour of gold nanoparticles in presence of chitosan

Chitosan (CS) is a biocompatible polysaccharide with positive charge that is widely used as a coating agent for negatively charged nanoparticles. However, the types of structures that emerge by combining CS and nanoparticles as well as their behaviour are still poorly understood. In this work, we characterize the nanocomposites formed by gold nanoparticles (AuNPs) and CS and study the influence of CS in the expected aggregation process that should experience those nanoparticles under the favourable conditions of low pH and high ionic strength. Thus, at the working CS concentration, we observe the existence of CS structures that quickly trap the AuNPs and avoid the formation of nanoparticle aggregates in environmental conditions that, otherwise, would lead to such an aggregation.

Cytotoxicity of GuttaFlow Bioseal, GuttaFlow2, MTA Fillapex, and AH Plus on Human Periodontal Ligament Stem Cells

Introduction: The aim of the present study was to evaluate the in vitro cytotoxicity of endodontic sealers (GuttaFlow Bioseal, GuttaFlow2, and MTA Fillapex) on human periodontal ligament stem cells (hPDLSCs). As a reference, AH Plus was compared with the more recent endodontic sealers regarding cell viability and cell attachment. Methods: Biological testing was carried out in vitro on hPDLSCs. Cell viability assay was performed by using eluates from each endodontic sealer. To assess cell morphology and attachment to the different sealers, the hPDLSCs were directly seeded onto the material surfaces and analyzed by scanning electron microscopy. Chemical composition of the sealers was determined by energy‐dispersive x‐ray, and eluates were analyzed by inductively coupled plasma mass spectrometry. Statistical differences were assessed by analysis of variance and Tukey test (P < .05). Results: Cell viability was evident after 24 hours in the presence of GuttaFlow Bioseal and GuttaFlow 2 but not in the case of AH Plus or MTA Fillapex. At 168 hours, GuttaFlow Bioseal and GuttaFlow 2 exhibited high and moderate cell viability, respectively, whereas AH Plus and MTA Fillapex revealed low rates of cell cell viability (P < .001). Finally, scanning electron microscopy studies revealed a high degree of proliferation, cell spreading, and attachment, especially when using GuttaFlow Bioseal disks. Conclusions: GuttaFlow Bioseal and GuttaFlow2 showed lower cytotoxicity than MTA Fillapex and AH plus. Further in vitro and in vivo investigations are required to confirm the suitability of GuttaFlow Bioseal for clinical application. HIGHLIGHTSThe sealerss extracts caused dose‐ and time‐dependent effects on hPDLSCs.GuttaFlow Bioseal exhibited better cytocompatibility than the other sealers.Further in vitro and in vivo investigations of GuttaFlow Bioseal are required.

Biocompatibility of New Pulp-capping Materials NeoMTA Plus, MTA Repair HP, and Biodentine on Human Dental Pulp Stem Cells

Introduction: The aim of the present study was to evaluate the in vitro cytotoxicity of MTA Repair HP, NeoMTA Plus, and Biodentine, new bioactive materials used for dental pulp capping, on human dental pulp stem cells (hDPSCs). Methods: Biological testing was carried out in vitro on hDPSCs. Cell viability and cell migration assays were performed using eluates of each capping material. To evaluate cell morphology and cell attachment to the different materials, hDPSCs were directly seeded onto the material surfaces and analyzed by scanning electron microscopy. The chemical composition of the pulp‐capping materials was determined by energy‐dispersive X‐ray and eluates were analyzed by inductively coupled plasma‐mass spectrometry. Statistical differences were assessed by analysis of variance and Tukey test (P < .05). Results: Cell viability was moderate after 24 and 48 hours in the presence of MTA Repair HP and NeoMTA Plus, whereas at 48 and 72 hours, Biodentine showed higher rates of cell viability than MTA Repair HP and NeoMTA Plus (P < .001). A cell migration assay revealed adequate cell migration rates for MTA Repair HP and NeoMTA Plus, both similar to the control group rates, meanwhile the highest cell migration rate was observed in the presence of Biodentine (P < .001). Scanning electron microscope studies showed a high degree of cell proliferation and adhesion on Biodentine disks but moderate rates on MTA Repair HP and NeoMTA Plus disks. Energy‐dispersive X‐ray pointed to similar weight percentages of C, O, and Ca in all 3 materials, whereas other elements such as Al, Si, and S were also found. Conclusions: The new pulp‐capping materials MTA Repair HP, NeoMTA Plus, and Biodentine showed a suitable degree of cytocompatibility with hDPSCs, and good cell migration rates, although Biodentine showed higher rates of proliferation time‐dependent. HighlightsResults of this work suggest that hDPSCs show suitable biological response in terms of cell viability, cell proliferation, and cell migration when in contact with extracts from NeoMTA Plus, MTA Repair HP, and Biodentine.NeoMTA Plus and MTA Repair HP exhibited similar cytocompatibility and cell attachment with hDPSCs, whereas Biodentine promotes higher proliferation rates, cell migration, and cell attachment.Further in vitro and in vivo investigations are required to contrast these results and to prove suitable clinical applications of NeoMTA Plus and MTA Repair HP.

Chitosan as stabilizing agent for negatively charged nanoparticles

Chitosan is a biocompatible polysaccharide with positive Z potential which can stabilize negative charged nanoparticles. Silk fibroin nanoparticles and citrate gold nanoparticles, both with negative Z potential, but they form aggregates at physiological ionic strength. In this work, we study the behavior of chitosan in solution when the ionic strength of the medium is increased and how the concentration of chitosan and the proportion of the two components (chitosan and AuNP or SFN) significantly affect the stability and size of the nanocomposites formed. In addition to experimental measurements, molecular modeling were used to gain insight into how chitosan interacts with silk fibroin monomers, and to identify the main energetic interactions involved in the process. The optimum values for obtaining the smallest and most homogeneous stable nanocomposites were obtained and two different ways of organization through which chitosan may exert its stabilizing effect were suggested.

Human Dental Pulp Stem Cells Exhibit Different Biological Behaviours in Response to Commercial Bleaching Products

The purpose of this study was to evaluate the diffusion capacity and the biological effects of different bleaching products on human dental pulp stem cells (hDPSCs). The bleaching gel was applied for 90, 30 or 15 min to enamel/dentine discs that adapted in an artificial chamber. The diffusion of hydrogen peroxide (HP) was analysed by fluorometry and the diffusion products were applied to hDPSCs. Cell viability, cell migration and cell morphology assays were performed using the eluates of diffusion products. Finally, cell apoptosis and the expression of mesenchymal stem cell markers were analysed by flow cytometry. Statistical analysis was performed using analysis of variance and Kruskal–Wallis or Mann–Whitney tests (α < 0.05). Significant reductions of approximately 95% in cell viability were observed for the 3 × 15 min groups (p < 0.001), while 1 × 30 min of PerfectBleach and 1 × 90 min of PolaNight resulted in reductions of 50% and 60% in cell viability, respectively (p < 0.001). Similar results were obtained in the migration assay. Moreover, the 3 × 15 min group was associated with cell morphology alterations and reductions of >70% in cell live. Finally, hDPSCs maintained their mesenchymal phenotype in all conditions. Similar concentrations of carbamide peroxide (CP) and HP in different commercial products exhibited different biological effects on hDPSCs.

Thermo-setting glass ionomer cements promote variable biological responses of human dental pulp stem cells

OBJECTIVE To evaluate the in vitro cytotoxicity of Equia Forte (GC, Tokyo, Japan) and Ionostar Molar (Voco, Cuxhaven, Germany) on human dental pulp stem cells (hDPSCs). METHODS hDPSCs isolated from third molars were exposed to several dilutions of Equia Forte and Ionostar Molar eluates (1/1, 1/2 and 1/4). These eluates were obtained by storing material samples in respective cell culture medium for 24h (n=40). hDPSCs in basal growth culture medium were the control. Cell viability and cell migration assays were performed using the MTT and wound-healing assays, respectively. Also, induction of apoptosis and changes in cell phenotype were evaluated by flow cytometry. Changes in cell morphology were analysed by immunocytofluorescence staining. To evaluate cell attachment to the different materials, hDPSCs were directly seeded onto the material surfaces and analyzed by scanning electron microscopy (SEM). The chemical composition of the materials was determined by energy dispersive X-ray (EDX) and eluates were analyzed by inductively coupled plasma-mass spectrometry (ICP-MS). Statistical analysis was performed with analysis of variance (ANOVA) and Students t-test (α<0.05). RESULTS Undiluted Equia Forte extracts led to a similar cell proliferation rates than the control group from 72h onwards. There were no significance differences between Equia Forte and Ionostar Molar in terms of cell apoptosis and phenotype. However, in presence of Equia extracts the migration capacity of hDPSCs was higher than in presence of Ionostar Molar (p<0.05). Also, SEM studies showed a higher degree of cell attachment when Equia Forte extracts were used. Finally, EDX analysis pointed to different weight percentages of C, O and Ca ions in glass ionomer cements, while other elements such as La, Al, Si, W, Mo and F were also detected. SIGNIFICANCE In summary, Equia Forte promoted better biological responses in hDPSCs than Ionostar Molar.

Density and refractive index data of binary and ternary mixtures of imidazolium-based ionic liquids, n-hexane and organic compounds involved in the kinetic resolution of rac-2-pentanol

This data article is related to the subject of the research article “Extraction of Organic Compounds Involved in the Kinetic Resolution of rac-2-Pentanol from n-Hexane by Imidazolium-based Ionic Liquids: Liquid-Liquid Equilibrium” (Montalbán et al., 2018) [1]. It contains experimental data of density and refractive index of binary and ternary mixtures of imidazolium-based ionic liquids, n-hexane and organic compounds involved in the kinetic resolution of rac-2-pentanol (rac-2-pentanol, vinyl butyrate, rac-2-pentyl butyrate or butyric acid) measured at 303.15 K and 1 atm. These data are presented as calibration curves which help to determine the composition of the ionic liquid-rich phase knowing its density or refractive index.

Predicting Density and Refractive Index of Ionic Liquids

The determination of the physicochemical properties of ionic liquids (ILs), such as density and refractive index, is essential for the design of processes that involve ILs. Density has been widely studied in ILs because of its importance whereas refractive index has received less attention even though its determination is rapid, highly accurate and needs a small amount of sample in most techniques. Due to the large number of possible cation and anion combinations, it is not practical to use trial and error methods to find a suitable ionic liquid for a given function. It would be preferable to predict physical properties of ILs from their structure. We compile in this work different methods to predict density and refractive index of ILs from literature. Especially, we describe the method developed by the authors in a previous work for predicting density of ILs through their molecular volume. We also correlate our experimental measure‐ ments of density and refractive index of ILs in order to predict one of the parameters knowing the other one as a function of temperature. As the measurement of refractive index is very fast and needs only a drop of the ionic liquid, this is also a very useful approach.