Poly retinoate

The work presented in the next section concerns the immobilization of retinoic acid by three polyamino acids poly(-L-lysine), poly(-L-arginine) and poly(-L-histidine). The mesomorphous structure of these complexes, which are prepared as nano-particles, has been examined. Then we will report on the physicochemical characteristics of water-soluble complexes formed between PEO-PLL block copolymers and retinoic acid. The structure in the solid-state and solution are discussed. Further the dissociation of the complex when changing the pH is reported. Finally, the immobilization of retinoic acid by PEI with different molecular weights is presented. 

Fig. 12 Substances used for complex formation and nanoparticles, (retinoic acid) All-trans retinoic acid, (PLA) poly(-L-arginine), (PLH) poly(-L-histidine), (PLL) poly(-L-ly-sine). As dispersing agent a tri-block copolymer was used. It consisted of ethylene oxide and propylene oxide (Poloxamer 188). Reprinted with permission from [142]. Copyright 2000 American Chemical Society...

Fig. 14 Wide-angle X-ray diagrams of crystalline all-trans retinoic acid (curve a) and its complexes with polyamino acids. In the curve of poly(L-arginine) retinoate and poly(L-lysine) retinoate (curves b and d, respectively) no crystalline reflections were found. However, three weak crystalline reflections are present in the curve of poly(L-histidine) retinoate at s=1.69, 2.48 and 2.73 nm-1 (curve c). This is indicative of a partially crystalline complex structure. Reprinted with permission from [142]. Copyright 2000 American Chemical Society...

In conclusion it was shown that the solid-state complexes formed by poly(L-arginine), poly(L-histidine) and poly(L-lysine) cations and retinoic acid can be prepared as films and nano-particles. The high content of retino-ate moieties, the absence of crystallinity and low particle sizes could make these complexes interesting as a new carrier for the delivery of retinoic acid, either transdermal or in body fluids. It may be speculated that supramolecu-lar structures such as the smectic A-like nano-particles of the tart-type pre-... 

In conclusion, it was found that complexes of poly(ethylene oxide)-h-poly(L-lysine) with retinoic acid with short poly(L-lysine) segments of 18 and 30 monomers form core shell micelles. The cores of the micelles contain a lamellar smectic A-like structure, formed by a poly(L-lysine) retinoate complex, which is surrounded by a corona of poly(ethylene oxide). Although the poly(L-lysine) chains are relatively short, they adopt an a-helical conformation to a pH as low as 9. This effective stabilization of the a-helix structure seems to be due to the formation of a protective surrounding coat of retinoate and a shell of poly(ethylene oxide). 

Sundquist, A.R. Stahl, W. Steigel, A. Sies, H. Separation of retinoic acid all-trans, mono-cis and poly-cis isomers by reversed-phase high-performance liquid chromatography. J.Chromatogr, 1993, 637, 201-205... 

Jeong YI, Song JG, Kang SS, Ryu HH, Lee YH, Choi C et al. Preparation of poly(DL-lactide-co-glycolide) microspheres encapsulating all-trans retinoic acid. International Journal of Pharmaceutics. June 18, 2003 259(l-2) 79-91. PubMed PMID 12787638. 

Cirpanli Y, Unlu N, Calls S, Hincal AA. Formulation and in-vitro characterization of retinoic acid loaded poly (lactic-co-glycolic acid) microspheres. Journal of Microencapsulation. December 2005 22(8) 877-889. PubMed PMID 16423759. 

Dinucci, D., and Chiellini, F. (2010) Poly(lactic-co-glycolic acid) electrospun fibrous meshes for the controlled release of retinoic acid. Acta Biomater.,... 

Kim, D. G., Jeong, Y. I., and Nah, J. W. 2007a. AU-trans retinoic acid release from polyion-complex micelles of methoxy poly(ethylene glycol) grafted chitosan. J. Appl. Polym. ScL 105 3246-3254. 

Thiinemaim, A. F., Beyermann, J., and Kukula, H. 2000. Polyfethylene oxide)-h-poly(L-lysine) complexes with retinoic acid. Macromolecules 33 5906-11. 

Fig. 3. HL60 cells were induced to differentiate by addition of 3 x 10- retinoic acid or 180 mM DMSO. Approximately 5 x 10 cells were isolated at various time points following addition of retinoic acid or DMSO and centrifuged, washed and the pellet was stored at 4°C until aU samples were ready for RNA processing. Total cellular RNA was isolated from the cells by the guani um isothiocyanate method. RNA was resolved on an agarose formaldehyde gel and mRNA for poly(ADP-ribose) polymerase was visutdized by hybridization and autoradiography as described earlier. Hybridization with actin was also performed to confirm that equal amounts of RNA were being compared (data not shown).

Molecular Cloning of cDNA for Human Placental Poly(ADP-Ribose) Polymerase and Decreased Expression of its Gene during Retinoic Acid-Induced Granulocytic Differentiation of HL-60 Cells... 

Jeong YI, et al. Polyion complex micelles composed of aU-trans retinoic acid and poly (ethylene glycol)-grafted-citosan. J Pharm Sd. 2006 95 2348-60. 

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