Liposomes large molecule entrapment

The use of liposomes as boron delivery vehicles for BNCT has been extensively studied, since liposomes can transport large amounts of boronated molecules, both hydrophobic and hydrophilic in nature, selectively into tumor cells. Three methods for incorporation of boron into liposomes have been reported incorporation of hydrophobic molecules into lipid bilayers, entrapment of hydrophilic molecules into the liposomes aqueous core, and the use of boronated lipids. Recently, PEG-based liposomes (DPPC/cholesterol/DSPC-PEG2000) have been used as effective carriers of boronated compounds within tumor tissues. Intraveuously injected B-PEG-liposomes on human pancreatic carcinoma xenografts in nude mice inhibited tumor growth after thermal neutron irradiation. The cationic liposome formulation (DOTAP/DOPC/DOPE) was used to deliver ortho-carboranyl P-lactoside (LCOB) aud l-methyl-ort/j< -carboranyl-2-hexylthioporphyrazine (H2PZ-COB) within DHD/K12/TRb (DHD) rat colon carcinoma and B16-F10 murine melanoma cell lines. Results from these studies show that a thirty-fold increase on the cellular uptake of B was obtained for the boronated compounds in the liposome formulation as compared with that of the BPA-fructose complex. 

Indeed, semi-synthetic minimal cells often consist of a liposome enclosing defined biochemical pathways, specifically pathways capable to synthesize proteins that could, in principle, close the circle towards a complete self-sustainability of the minimal cell in other words, the different components of the minimal cells can cooperate to restore themselves. As of today, only a few papers have been published dealing with theoretical simulations, at different detail level, of PS behavior and time course [7,15 17], and only three deal with PS entrapped in liposomes [18 20]. This last condition is very interesting since the smaller the liposome, the lower the probability that a large amount of molecules of each constituent chemical species be entrapped in the volume of the liposome. This implies that a standard simulation of PS based on deterministic ODE formalism is no longer suitable to describe a biochemical system beyond the deterministic limit. If even a single chemical species is present with only a few molecules, the behavior of all the PS is turned to stochastic. 

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