Study about Overall Adhesion-Spreading Process of Liposomes on a Gold Electrode. Influence of the Presence of CdTe Quantum Dots
Notice bibliographique
Résumé
The utilization of quantum dots (QDs) it has been grown up into the material science area, because these nanoparticles have particular optical and electronic properties. These properties are dependent on the particle size, which can be controlled by the modification of some experimental conditions: temperature, reaction time, pH and molar ratio of precursors. QDs present a wide absorption spectrum, narrow emission fluorescence spectrum, high photo-stability, tunable band gap, high quantum yield, among others. These properties have allowed its application in different areas such as photovoltaic cells, biomedicine, chemical analysis, biosensors and biomarkers. However, particularly in the medicine field is very important to know what is the effect of QDs in contact with cell membranes. An approximation to this process could be the utilization of structures like lipid vesicles or liposomes, which also can be used as drug and biomarkers carriers. Some authors [1], [2] have used electrochemical methods in the study of liposomes, because the vesicles deposition process (adhesion and spreading processes) on metallic electrodes are similar to the lipid membranes fusion, providing information about e.g. exo- and endocytosis processes. In this context, this work is related with the influence of the interaction between CdTe QDs and 1,2-dimyristoyl-sn-phosphatidylcholine (DMPC) liposomes on the overall adhesion-spreading processes of liposomes modified by QDs. Synthesis of CdTe QDs was carried out in aqueous media, by using CdCl2 and Na2TeO3 as precursors, mercaptosuccinic acid (MSA) as capping agent and NaBH4 as reducing agent. Using a Doehlert’s experimental design was possible the optimization of the QDs sizes controlling the synthesis variables, i.e. temperature, reaction time, pH and molar ratio of precursors. After QDs were purified through ultracentrifugation with 1:1 water:isopropanol mixture and re-suspended in a buffer solution (borate buffer; pH 9.20). Finally, these were characterized by UV-Vis spectroscopy, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). On the other hand, DMPC liposomes were prepared by dissolving DMPC in chloroform, then evaporating solvent with Argon and suspending the lipids in borate buffer. Lipid suspension was cooled with liquid nitrogen and then heated below the phase transition temperature. Finally, lipids were extruded to obtain large unilamellar vesicles. After, the DMPC liposomes were deposited on gold electrode and characterized by CV observing the coverage degree by charge analysis. Additionally, the overall adhesion-spreading process of liposomes on gold electrode was characterized by means of chronoamperometry technique analyzing the corresponding current-time transients. Both analysis were performed after the mixing with CdTe QDs. The results show a decrease in the constant rate values of the adhesion-spreading processes of DMPC liposomes on gold electrode suggesting that the interaction CdTe(QD)-DMPC produces an increase in the activation energy of the lipid membranes fusion. References [1] V. A. Hernández and F. Scholz, “The Electrochemistry of Liposomes,” Isr. J. Chem., vol. 48, no. 3–4, pp. 169–184, 2008. [2] O. Pierrat, N. Lechat, C. Bourdillon, and J.-M. Laval, “Electrochemical and Surface Plasmon Resonance Characterization of the Step-by-Step Self-Assembly of a Biomimetic Structure onto an Electrode Surface,” Langmuir, vol. 13, no. 15, pp. 4112–4118, 1997.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».