Pegylated polymers copolymer

Polymeric micelles Poloxamer-like block copolymers PEG and lipophilic polymer copolymers PEGylated lipids Dialysis, emulsification, or film method 35,36... 

Rieger, J. Grazon, C. Charleux, B. Alaimo, D. Jerome, C. Pegylated thermally responsive block copolymer micelles and nanogels via in situ RAFT aqueous dispersion polymerization. J. Polym. Sci. A Polym. Chem. 2009, 47 (9), 2373-2390. 

Fig. 15 A Polymer-enzyme liposome therapy (PELT) relies on the liberation of drug from liposomes by the action of a polymer-phospholipase conjugate. B PEGylated liposomal doxorubicin (Doxil) activated by HPMA copolymer-Gly-Gly-phospholipase C conjugate. C Comparison of enzymatic activity of free phospholipase C and HPMA copolymer Gly-Gly-phospholipase C in vitro. Release of doxorubicin from Daunoxomes in the presence of phospholipase C ( ), HPMA copolymer-Gly-Gly-phospholipase C (A) or Triton X-100 (1%) ( ) and in the absence of enzyme as a control ( ) (R. Satchi and R. Duncan, unpublished results)...

Figure 9.4 Chemical structure of the polymers employed in the experimental tests shown in figures (a) Poly-e-caprolactone (PCL) (b) Poly-hexadecyl cyanoacrylate (PHDCA) and (c) P(methoxypolyethylenglycol cyanocrylate-co-hexadecyl-cyanocrylate) (poly(MePEGCA-co-HDCA, also referred to as PEGylated copolymer.

The solvent used can have a large influence on final particle size, even much larger than hydrodynamics the comparison can be difficult at the same operating conditions as a consequence of the different solubility, but Figures 9.5 and 9.6 evidence that in the case of PEGylated copolymer and PHDCA at same flow rate and initial polymer concentration, in THF, twofold and more than threefold larger particles are obtained, respectively. 

Peracchia et al. [36] had reported that for the PEGylated copolymer the entrapment of PEG chains within the particle core seems to be more pronounced when acetone is used as solvent instead of THF actually the structure of the PEG chain seemed to be influenced by the formation process, and in particular by its rate, that decreases, moving from solvent-displacement with water and acetone, to solvent-displacement with water and tetrahydrofuran. The different coverage of the nanoparticle by PEG chains, obtained in different operating conditions, may explain the lower absolute value of Zeta potential obtained using THF at any initial polymer concentration, and eventually also the values observed at low concentration in acetone lower than in the higher concentration range [70,96,106]. 

Particle size and size dependence on polymer concentration are not generally correlated, as it can be seen that higher values of the alpha exponent are found for the PEGylated copolymer and PHDCA that form the smallest particles. 

In the case of nanocapsules with an oily core, the situation is more complex data obtained with the PEGylated copolymer evidenced that at low vale of the MR ratio in a certain range of concentrations, the size is dependent only on the oil-to-polymer ratio, but at higher values the total concentration also becomes effective [66,107]. 

The mechanism of quench is not completely understood fast dilution can suppress aggregation but, depending on the solubility of the different chemical components in the solvent/antisolvent mixture, can induce further polymer precipitation an XPS study on the PEGylated copolymer evidenced no significant variation in the surface... 

Figure 9.14 Influence of solvent evaporation process on flnal particle size for PCL = 14,000) and PEGylated copolymer (initial concentration 6 mg/mL in acetone) both nanopheres of pure polymer and nanocapsules containing Miglyol are shown. Nanoparticles size measured after synthesis and quench in CIJM-dl (open symbols) and after solvent evaporator in a rotating evaporator (filled symbols) PCL...

The results shown in the previous subsections and the data published in the literature referenced there, evidence the role of mixing, with similar results for the different polymers investigated, even if significantly influenced by the solvent considered thus in this part some comparisons between different intensive mixers will be shown, using the lower molecular weight PCL and the PEGylated copolymer, in acetone, as test systems. 

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