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Nanoparticles at Biomimetic Interfaces: A Combined Experimental and Simulation Study on Charged Gold Nanoparticles/Lipid Bilayers Interfaces
摘要： The poor understanding of the interaction of nanomaterials with biologically relevant interfaces is recognized as one of the major issues currently limiting the development of nanomedicine. The central purpose of this study is to compare experimental (Confocal Microscopy, Fluorescence Correlation Spectroscopy, X-ray Reflectivity) and computational (Molecular Dynamics simulations) results to thoroughly describe the interaction of cationic gold nanoparticles (AuNP) with mixed zwitterionic/anionic lipid membranes. The adhesion of AuNPs to the lipid membrane is investigated on different length scales from a structural and dynamical point of view; with this approach, a series of complex phenomena, spanning from lipid extraction, localized membrane disruption, lateral phase separation and slaved diffusion, are characterized and interpreted from a molecular level to macroscopic observations.
关键词： Nanoparticles,Gold Nanoparticles,Molecular Dynamics,X-ray Reflectivity,Fluorescence Correlation Spectroscopy,Lipid Bilayers,Biomimetic Interfaces,Confocal Microscopy
更新于2025-09-04 15:30:14
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Charge and Coordination Directed Liposome Fusion onto SiO2 and TiO2 Nanoparticles
摘要： TiO2 and SiO2 are very useful materials for building biointerfaces. A particular interesting aspect is their interactions with lipid bilayers. Many past research efforts focused on phosphocholine (PC) lipids, which form supported lipid bilayers (SLB) on SiO2 at physiological conditions but are adsorbed as intact liposomes on TiO2. Low pH was required to form PC SLBs on TiO2. This work intends to understand the surface forces and chemistry responsible for such differences. Two charge neutral lipids: 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 2-((2,3-bis(oleoyloxy)propyl)dimethylammonio)ethyl ethyl phosphate (DOCPe); and two negatively charged lipids: 1,2-dioleoyl-sn-glycero-3-phospho-L-serine (DOPS) and 2-((2,3-bis(oleoyloxy)propyl)dimethylammonio)ethyl hydrogen phosphate (DOCP) were used. Using calcein leakage assays, adsorption measurement, cryo-TEM, and washing, we concluded that charge is the dominating factor on SiO2. The two neutral lipids form SLB on SiO2 at pH 3 and 7, but the two negatively charged ones cannot form. On TiO2, both charge and coordination chemistry are important. The two anionic lipids formed SLB from pH 3 to 10. DOCP had stronger affinity than DOPS likely due to the tighter terminal phosphate binding of the former. The two neutral liposomes formed SLB only at pH 3, where phosphate interaction and van der Waals force are deemed important. The pH 3 prepared TiO2 DOPC SLBs are destabilized at neutral pH, indicating reversible nature of the interaction. This work has provided new insights into two important materials interacting with common liposomes, which are important for reproducible biosensing, device fabrication, and drug delivery applications.
关键词： coordination chemistry,liposome fusion,SiO2,TiO2,charge,supported lipid bilayers
更新于2025-09-04 15:30:14
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SENSITIVITY TO ENVIRONMENTAL STRESS OF PRATA,JAPIRA AND VITóRIA BANANA CULTIVARS PROVEN BY CHLOROPHYLL a FLUORESCENCE
摘要： This study aimed to evaluate the physiological responses to environmental stress during pre- and post-harvest of the following banana cultivars: Prata (AAB), Japira (AAAB) and Vitoria (AAAB). Analyses were carried out on young plants at vegetative stage (daughter-plant) and adult plants at reproductive stage (mother-plant). The experimental design was completely randomized. In the in vivo pre-harvest analysis were used seven replications, in a factorial scheme (3x2x2), three cultivars and two stages (vegetative and reproductive) and two collection periods (March and June). For the analysis of post-harvest quality were used five replications in a factorial design (3x2x5), corresponding to three cultivars, two development stages and five periods of post-harvest analysis, carried out every two days from stage 4 of fruit ripening. The chlorophyll a fluorescence emission kinetics showed low photochemical performance of the three cultivars in June, a period characterized by lower temperatures and water deficit. Prata was the cultivar with the lowest tolerance to abiotic physiological behavior changes, which also reflected in fruit quality, because there was a change in physical and physicochemical parameters. Japira and Vitoria cultivars showed similar physiological responses in the pre- and post-harvest periods, according to their phylogenetic proximity. The total performance index, i.e., the conservation of energy absorbed by PSII up to the reduction of the final PSI acceptors (PItotal) and the di-malonic aldehyde (MDA) content were significantly higher in Japira and Vitoria cultivars compared to Prata cultivar in the reproductive phase. There was no significant change in the potential quantum efficiency of PSII (FV / FM = jP0) among the three cultivars. It was concluded that Japira and Vitoria cultivars showed greater plasticity to tolerate or even adapt to abiotic variations keeping higher fruit yield. PItotal is the most sensitive parameter during the banana life cycle and important tool for distinguishing different cultivars yields.
关键词： Chlorophyll fluorescence,Musa spp.,post-harvest quality,lipid peroxidation,pigments
更新于2025-09-04 15:30:14