Phospholipid copolymers

Watanabe et al. reported stereo-complex material by enantiomeric PLA graft-type phospholipid copolymers as tissue engineering scaffolds. The copolymers as cell-compatible materials are prepared using a phospholipid copolymer composed of 2-methactyloyloxyethyl phosphotylcholine, n-butyl methacrylate, and enantiomeric PLLA and PDLA macromonomers. The porous scaffold presents advantages for tissue engineering, including cell compatibility using phospholipid copolymer, adequate cell adhesion by PLA... 

Vesicles for use as materials can be divided into two categories naturally occurring vesicles, or liposomes, which are composed of natural amphiphiles, usually phospholipids and polymer vesicles, which are generally composed of block copolymers. 

Similarly comb-like copolymers of vinyl pyrollidone and vinyl alkyl amines were shown [446] to influence the permeability of negatively charged phospholipid liposomes containing encapsulated carboxyfluorescein. At a pH of approximately 7, the copolymers allowed permeability and solute release due to polymer/liposome complex formation and disruption of the phospholipid membrane. 

The synthesis of narrowly distributed polycarbobetaines 17a, 18, and 19 has already been mentioned. Block copolymers containing these structures and styrene were prepared hkely by functionalization of reactive block copolymer precursors [161]. Well-defined block copolymers with phospholipid sequences were prepared using both RAFT and ATRP techniques. 

Phospholipid polymers having a 2-methacryloylox-yethyl phosphorylcholine (MPC) were investigated as a solubilizer for paclitaxel. The paclitaxel solubility was observed to increase up to 5.0mg/ml in the presence of a copolymer of MPC and Ai-butyl methacrylate (BMA), poly(MPC-co-BMA), with 70mol% of the BMA unit. The MPC polymer forms a polymer aggregate with the diameter of 23 nm, called a polymeric lipid nanosphere, in aqueous media by hydrophobic interaction, which may solubilize hydrophobic drugs. 

Weight calculation is based on molar ratio DOPEiCHEMs (3 2) (24). For the preparation of 2 ml of sterically stabilized liposomal suspensions with total phospholipids concentration 3 mM and copolymers at various contents from 2.5 to 10 mol % (with respect to total lipid content) mix in glass tubes 0.0036 mmol DOPE (268 pi of DOPE stock solution (10 mg/ml)), 0.0024 mmol CHEMs (233 pi of CHEMs... 

The acidification of endosomal compartments, as they evolve toward lysosomes is a well-described phenomenon (1) that can be exploited to design drug delivery systems capable of releasing their contents after endocytosis. Enhanced cytoplasmic drug concentrations can therefore be achieved with smart formulations, which are sensitive to acidic pHs. For this purpose, liposomal formulations are attractive, because their deformable phospholipid bilayers can be rapidly disrupted to trigger drug release. In this section, ionizable copolymers of ISTisopropylacrylamide (NIPAM) are anchored in the phospholipid membrane and used to destabilize the bilayer upon acidification of the environment. 

Emulsions are one of the most widely studied colloidal dispersion systems for the delivery of drugs (205,206). The oil-in-water emulsion is made of oil dispersed in an aqueous phase with a suitable emulsifier such as phospholipids and non-ionic or ionic surfactants. Castor oil or soybean oil is predominantly used as the core oil phase. Non-ionic surfactants such as Tween, Span, Brij, and pluronic copolymers are used as co-emulsifiers. The ionic co-emul-... 

In this paper, we examine the Interactions of pyran copolymer with model biomembranes of two kinds 1) the human red blood cell membrane (or red cell "ghost") and 11) multilamellar suspensions (liposomes) of dlpalmltoylphosphatldylchollne (DFPC), a pure synthetic phospholipid. Each of these systems offers advantages In studies of polymer-cell surface Interaction The red cell membrane, idille complex. Is still the most readily Isolated and best understood of the membranes of nonnal human cells, and Its molecular architecture Is, In a general way at least, typical of such membranes. The pure phospholipids provide a much simpler biomembrane model, with the prospect of yielding more complete Interpretation of experimental observations. 

Ca at concentrations typical for divalent ions in human plasma, promotes the association of pyran copolymer with a pure phospholipid (dipalmitoylphosphatidylcholine) and with intact erythrocytes. This may suggest a more general mediation by divalent ions of the cell surface interactions and pharmacological properties of pyran copolymer. 

Interestingly enough, the storage modulus of diblock copolymers is weakened by increasing the mol fraction of one of the substituents of the diblock, unfunctionalized PEG chains [47], This is similar to the current situation if a DSPE-PEG2000 lipopolymer is considered a short diblock copolymer and the mixed-in phospholipid is considered one of the substituents of the diblock. 

---