CHARACTERIZATION OF THE MAIN PHASE TRANSITION IN 1,2-DIPALMITOYL-PHOSPHATIDYLCHOLINE LUVS BY¹H NMR*

Abstract

The main phase transition (Tm) of 100 nm large unilamellar vesicles (LUVs) of 1,2-dipalmitoylphosphatidylcholine (DPPC) was investigated using 1H NMR (proton magnetic resonance) in deuterium oxide, and both DSC (differential scanning calorimetry) and IR (infrared) spectroscopy in water and deuterium oxide. The ability of 1H NMR to determine Tm was demonstrated and the values obtained were in general agreement with those observed with DSC and IR. However, the temperature range of the transition observed by NMR was significantly broader than that observed with either DSC or IR. The effect of deuterium oxide on Tm was studied by comparing results obtained in water and deuterium oxide with DSC and IR. The results showed no significant difference in Tm or temperature range of transition determined in these solvents.

Novel antimicrobial peptides that exhibit activity against select agents and other drug resistant bacteria

“…Previously we have reported the preparation of liposomes using this procedure resulted in a homogeneous population of liposomes with >95% of the particles falling into the particle size range of 70-100 nm. 89 We have also previously shown by 31 P NMR that these liposomes are unilamellar. 89 The starting concentration of 35 mM of the liposomes was based on the dry lipid weight.…”

“…89 We have also previously shown by 31 P NMR that these liposomes are unilamellar. 89 The starting concentration of 35 mM of the liposomes was based on the dry lipid weight. The extrusion process yields approximately 125 lL out of starting volume of 150 lL liposome.…”

“…87,88 The solution was passed through a 100 nm pore size polycarbonate membrane 21 times. 89 The self-quenching efficiency (Q) for each lipid suspension was, at minimum, 80% and calculated using the following equation: Q = (1 À (F 0 /F T )) Â 100% where F 0 and F T are the background fluorescence of the lipid suspension and the total fluorescence after the addition of Triton X, respectively. 97-100…”

The association of dimethylsulfoxide and model membranes studied by pulse‐field gradient NMR

“…Vesicles were characterised in the usual manner [23] using light scattering techniques to determine the particle size distribution and 31 P NMR techniques to establish lamellarity.…”

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“…The final lipid concentration was calculated based on the weight of the dried lipid (Wieprecht, Apostolov, Beyermann, et al, 2000) (Russell et al, 2010) . Kennedy and co-workers previously reported the preparation of LUVs using this procedure resulting in a homogeneous population of LUVs with >95% of the particles falling into the particle size range of 70-100 nm (Kennedy et al, 2002). We have also previously shown by 31 P NMR that these LUVs are unilamellar (Kennedy et al, 2002).…”