9 research outputs found
Quantitative Evaluation of Bioorthogonal Chemistries for Surface Functionalization of Nanoparticles
We present here a highly efficient and chemoselective
liposome
functionalization method based on oxime bond formation between a hydroxylamine
and an aldehyde-modified lipid component. We have conducted a systematic
and quantitative comparison of this new approach with other state-of-the-art
conjugation reactions in the field. Targeted liposomes that recognize
overexpressed receptors or antigens on diseased cells have great potential
in therapeutic and diagnostic applications. However, chemical modifications
of nanoparticle surfaces by postfunctionalization approaches are less
effective than in solution and often not high-yielding. In addition,
the conjugation efficiency is often challenging to characterize and
therefore not addressed in many reports. We present here an investigation
of PEGylated liposomes functionalized with a neuroendocrine tumor
targeting peptide (TATE), synthesized with a variety of functionalities
that have been used for surface conjugation of nanoparticles. The
reaction kinetics and overall yield were quantified by HPLC. Reactions
were conducted in solution as well as by postfunctionalization of
liposomes in order to study the effects of steric hindrance and possible
affinity between the peptide and the liposome surface. These studies
demonstrate the importance of choosing the correct chemistry in order
to obtain a quantitative surface functionalization of liposomes
Fusion or stabilization alone for acute distractive flexion injuries in the mid to lower cervical spine?
Monitoring the Chemical Production of Citrus-Derived Bioactive 5-Demethylnobiletin Using Surface-Enhanced Raman Spectroscopy
Understanding Detergent Effects on Lipid Membranes: A Model Study of Lysolipids
Lysolipids and fatty acids are the natural products formed by the hydrolysis of phospholipids. Lysolipids and fatty acids form micelles in solution and acts as detergents in the presence of lipid membranes. In this study, we investigate the detergent strength of a homologous series of lyso-phosphatidylcholine lipids (LPCs) on 1-palmitoyl-2-oleyl-sn-glycerol-3-phosphatidylcholine (POPC) lipid membranes by use of isothermal titration calorimetry and vesicle fluctuation analysis. The membrane partition coefficient (K) and critical micelle concentration (cmc) are determined by isothermal titration calorimetry and found to obey an inverse proportionality relation (cmc·K ∼ 0.05–0.3). The partition coefficient and critical micelle concentration are used for the analysis of the effect of LPCs on the membrane bending rigidity. The dependency of the bending rigidity on LPC membrane coverage has been analyzed in terms of a phenomenological model based on continuum elastic theory, which yields information about the curvature-inducing properties of the LPC molecule. The results reveal: 1), an increase in the partition coefficient with increasing LPC acyl-chain length; and 2), that the degree of acyl-chain mismatch between LPC and POPC determines the magnitude of the membrane mechanical perturbation per LPC molecule in the membrane. Finally, the three-stage model describing detergent membrane interaction has been extended by a parameter DMCI, which governs the membrane curvature stability in the detergent concentration range below the cmc-value of the LPC molecule