Polymer/lipid

Polymer/lipid and polymer/protein ratios, spanning a rather wide range, were adopted to highlight their influence on nanosphere sizes and physical stability of the dispersions. 

A series of nanoparticle suspensions was prepared according to this technique by varying protein concentration, polymer/lipid ratio, and type of solvent used to dissolve the polymer in order to establish the best experimental conditions. 

AnM,/PeglVE copolymer and a 10 1 2 polymer/lipid/protein weight ratio was used. 

Whitfield, C., Amor, P.A., Koplin, R. Modulation of the surface architecture of Gram-negative bacteria by the action of surface polymer lipid A-core ligase and by determinants of polymer chain length. Mol Microbiol 23 (1997) 629-638. 

New functions can be obtained by modifications of SLNs. Incorporation of Tween 80 and Poloxamer 188 can stabilize SLNs to achieve long-circulating or crossing blood-brain barrier effects [112], Recently, novel nanoparticles called polymer-lipid hybrid nanoparticles (PLNs) were developed [113]. They can entrap cationic anticancer agents (e.g., doxorubicin) effectively by incorporation of an anionic lipophilic polymer into lipids to treat multidrug-resistant (MDR) cancers. 

Wong, H. L., Bendayan, R., Rauth, A. M., and Wu, X. Y. (2006), Simultaneous delivery of doxorubicin and GG918 (Elacridar) by new polymer-lipid hybrid nanoparticles (PLN) for enhanced treatment of multidrug-resistant breast cancer, J. Controlled... 

Water-soluble polymers conjugated with lipids can form micelles in aqueous media, and they can be used for the solubilization and enhanced delivery of a variety of sparingly soluble drugs. The basic structures of these polymer-lipid conjugates are similar to amphiphilic block copolymers except for the fact that hydrophobic parts are composed of lipids instead of hydro-phobic polymers. For example, a hydrophilic PEG block is conjugated with phosphatidylethanolamine. ... 

Hydrate the polymer/lipid film with 0.9 mL of HPTS/DPX-containing HEPES buffer (see Note 2). Vortex and leave the mixture to rest overnight protected from light, at 4°G, to ensure complete lipid hydration (see Note 5). 

Already, a wide variety of materials have been used in the preparation of nanosystems, both organic (mainly polymeric) and inorganic, as seen in Table 1 polymers, lipids, phospholipids, metals, CNTs, and ceramics have all been employed to date. 

Polymer-lipid mixtures were prepared by hydrating the dry lipid (L-a-phosphatldylchollne, dipalmitoyl Sigma Chemical Co.) in 50 mM Tris (tris(hydroxymethyl)amlnomethane) buffer, pH 7.4 containing pyran copolymer at a concentration of 1 mg/ml. The final lipid concentration was also 1 mg/ml. Ca2+ was added In the form of CaCl2- Thermal transitions of lipid samples were recorded at a heating rate of 12 C/hr. 

Kuhl TL, Majewski J, Howes PB, Kjaier K, von Nahmen A, Lee KYC, Ocko B, Israelachvili JN, Smith GS (1999) Packing stress relaxation in polymer-lipid monolayers at the air-water interface an X-ray grazing-incidence diffraction and reflectivity study. J Am Chem Soc 121 7682-7688... 

Firestone et al. investigated the relationship between the molecular architecture of a series ofpoly(ethyleneoxide)-b-poly(propylene oxide) (PEO—PPO) di- and triblock copolymers and the nature of their interactions with lipid bilayers [213], The number of repeat units in the hydrophobic PPO block has been found to be a critical determinant for the polymer-lipid bilayer association. Further studies showed that temperature, polymer architecture and concentration also control the mode of interaction of PEO—PPO—PEO copolymers with lipid bilayers. Increasing either the number of repeat units in the PEO block or the polymer concentration promotes a greater degree of structural ordering [197],... 

Even though polymer-lipid interactions find already a number of biomedical applications, these systems still lack systematic investigations to achieve a better understanding of the ongoing mechanisms on molecular level. Without a doubt, this research will undergo further progress. 

Implanted polymeric materials can also adsorb and absorb from the body various chemicals that could also effect the properties of the polymer. Lipids (triglycerides, fatty acids, cholesterol, etc.) could act as plasticizers for some polymers and change their physical properties. Lipid absorption has been suggested to increase the degradation of silicone rubbers in heart valves (13). but this does not appear to be a factor in nonvascular Implants. Poly(dimethylsiloxane) shows very little tensile strength loss after 17 months of implantation (16). Adsorbed proteins, or other materials, can modify the interactions of the body with the polymer this effect has been observed with various plasma proteins and with heparin in connection with blood compatibility. 

Polymer films have been very widely applied to modify the surfaces of chemical sensors both for solution and gas phase measurements. Solution coating has been used to coat quartz crystal oscillators [91-93, 112] and SAW devices [113, 114] with various polymeric adsorbates and polymer/lipid mixtures [90, 94] to prepare arrays of sensors for use in gas sensing and odor evaluation and discrimination. 

Wong, H.L. A.M. Rauth R. Bendayan J.L. Manias M. Ramaswamy Z. Liu S.Z. Erhan X.Y. Wu. A new polymer-lipid hybrid nanoparticle system increases cytotoxicity of doxorubicin against multidrug-resistant human breast cancer cells. Pharm. Res. 2006, 23, 1574—1585. 

Woodle M C, Engbers C M, Zalipsky S (1994). New amphiphathic polymer-lipid conjugates forming long-circulating reticuloendothelial system-evading liposomes. Biocon-jug. Chem. 5 493-496. 

BBS, blood-brain barrier LDL, low-density lipoprotein PLN, polymer-lipid hybrid nanoparticles SLN, solid lipid nanoparticles. 

Wong HL, Rauth AM, Bendayan R, Wu XY. Combinational treatment with doxorubicin and GG918 (Elacridar) using polymer-lipid hybrid nanoparticles (PLN) and evaluation of strategies for multidrug-resistance reversal in human breast cancer cells. 

Wong HL, Bendayan R, Rauth AM, Xue HY, Babakhanian K, WuXY. Amechanistic study of enhanced doxorubicin uptake and retention in multidrug resistant breast cancer cells using a polymer-lipid hybrid nanoparticle (PLN) system. J Pharmacol Exp Ther 2006 317 1372-1381. 

WongHL, Rauth AM, Bendayan R, WuXY. Evaluation of the in vivo efficacy, toxicity and lymphatic drainage of loco-regional administered polymer-lipid hybrid nanoparticles (PEN) loaded with doxorubicin in a murine solid tumor model. Eur J Pharm Biopharm 2007 65 300-308. 

Albertini B, Passerini N, Di Sabatino M, Vitali B, Brigidi P, Rodriguez L (2009) Polymer-lipid based muco-adhesive microspheres prepared by spray-congealing for the vaginal delivery of econazole nitrate. European Journal of Pharmaceutical Sciences 36 591-601. 

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