Liposomes represent promising carriers for drug delivery applications. To maximize this potential, there has been significant interest in developing liposomal systems encapsulating molecular cargo that are highly stable until their contents are released remotely in a controlled manner. Herein, we describe the design, synthesis, and analysis of a photocleavable analogue of the ubiquitous lipid phosphoatidylcholine (PC) for the development of highly stable and controllable photodisruptable membranes. Our strategy was to develop a lipid that closely mimics the structure of PC to optimize favorable properties including biocompatibility and stability of subsequent liposomes when mixed with lipids possessing a broad range of physicochemical properties. Thus, NB-PC was designed, which contains a photocleavable 2-nitrobenzyl group embedded within the acyl chain at the sn-2 position. Following the synthesis of NB-PC, liposome disruption efficacy was evaluated through photolysis studies involving the detection of nile red release. Studies performed using a range of liposomes with different percentages of NB-PC, PC, phosphatidylethanolamine (PE), cholesterol, and polyethylene glycol-PE (PEG-PE) demonstrated minimal background release in controls, release efficacies that correlate directly with the amount of NB-PC incorporation, and that release is only minimally impacted by the inclusion of the lipids PE and cholesterol that possess disparate properties. These results demonstrate that the NB-PC system is a highly stable, flexible, and tunable system for photoinitiated release from liposomal systems.
For drug delivery purposes, the ability to conveniently attach a targeting moiety that will deliver drugs to cells and then enable controlled release of the active molecule after localization is desirable. Towards this end, we designed and synthesized clickable and photocleavable lipid analog 1 to maximize the efficiency of bioconjugation and triggered release. This compound contains a dibenzocyclooctyne group for bioorthogonal derivatization linked via a photocleavable 2-nitrobenzyl moiety at the headgroup of a synthetic lipid backbone for targeting to cell membranes. To assess delivery and release using this system, we report fluorescence-based assays for liposomal modification and photocleavage in solution as well as through surface immobilization to demonstrate successful liposome functionalization and photoinduced release. In addition, fluorophore delivery to and release from live cells was confirmed and characterized using fluorescence microscopy and flow cytometry analysis in which 1 was delivered to cells, derivatized and photocleaved. Finally, drug delivery studies were performed using an azide-tagged analog of camptothecin, a potent anti-cancer drug that is challenging to deliver due to poor solubility. In this case, the ester attachment of the azide tag acted as a caging group for release by intracellular esterases rather than through photocleavage. This resulted in a dose-dependent response in the presence of liposomes containing delivery agent 1, confirming the ability of this compound to stimulate delivery to the cytoplasm of cells.
Chemical bonding and the electronic structure of the trans 2,2',6,6'-tetrafluoroazobenzene negative ion have been studied using collision-induced dissociation as well as photodetachment-photoelectron spectroscopy and the experimental results for different properties were compared with the corresponding values calculated using ab initio quantum chemistry methods. The trans 2,2',6,6'-tetrafluoroazobenzene anion was prepared by atmospheric pressure chemical ionization for the collision induced dissociation (CID) experiment and through thermal electron attachment in the photodetachment-photoelectron spectroscopy experiments. The adiabatic electron affinity of trans 2,2',6,6'-tetrafluoroazobenzene was measured to be 1.3 ± 0.10 eV using 355 nm, 488 nm, and 532 nm photodetachment photons and the vertical detachment energy was measured to be 1.78 ± 0.10 eV, 2.03 ± 0.10 eV, and 1.93 ± 0.10 eV, respectively. The adiabatic electron affinity was calculated employing different ab initio methods giving values in excellent agreement with experimental results. Energy resolved collision induced dissociation experiment study of the precursor anion resulted in 1.92 ± 0.15 eV bond dissociation energy for the collision process yielding [C6H3F2](-) fragment ion at 0 K. Calculations using different ab initio methods resulted in a bond dissociation energy ranging from 1.79 to 2.1 eV at 0 K. Two additional CID fragment ions that appear at higher energies, [C6H2F](-) and [C6H](-), are not results of a single bond cleavage. The occurrence of [C6H](-) is of particular interest since it is the first anion to be observed in the interstellar medium.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.