Concentration Dependent Structural Ordering of Poloxamine 908 on Polystyrene Nanoparticles and Their Modulatory Role on Complement Consumption
Adsorption of poloxamine 908, a tetrafunctional polyethylene oxide (PEO)-polypropylene oxide ethylenediamine block copolymer, onto the surface of monodispersed polystyrene nanoparticles (232±0.33 nm) follows a bimodal pattern. Initially, the isotherm follows a Langmuir profile with a plateau observable over a very narrow equilibrium poloxamine concentration (0.0018–0.0031 mM). The isotherm then begins to rise again, reaching a final plateau at equilibrium poloxamine concentrations above 0.0089 mM. Similarly, the profile of the adsorbed layer thickness of poloxamine on the surface of nanoparticles is bimodal. The first plateau corresponds to a thickness of 4.6±0.07 nm, which occurs over the same range of poloxamine concentrations as in the initial plateau of the adsorption isotherm. The second plateau corresponds to a thickness of 9.53±0.32nm, observable at a minimum poloxamine concentration of 0.0067 mM. By using a calculated radius of gyration of a PEO chain in poloxamine as 3.1 nm, these observations reflect dynamic changes in the arrangement of surface projected PEO chains; a mushroom-like conformation at the first plateau region of the adsorption isotherm, followed by a transition into a brush-like conformation. These conformational changes are also reflected in rheological studies; the apparent viscosity of nanoparticles in which the PEO chains are in mushroom conformation is considerably higher than particles displaying the brush conformation. Further, atomic force microscopy studies (height profile and phase lag measurements) corroborated that the proposed poloxamine concentration dependent transition of surface associated PEO chains from mushroom to brush appearance is conserved when nanoparticles are dried under ambient conditions. Finally, we compared the influence of the surface PEO characteristics on complement consumption in human serum. Our results show complement-activating nature of all poloxamine-coated nanoparticles. However, complement consumption is reduced substantially with particles bearing a minimum of 11448 poloxamine molecules on their surface, thus demonstrating the importance of PEO surface density as well as brush conformation in suppressing complement consumption. This relationship between surface characteristics of poloxamine nanoparticles and their in vivo performance is discussed.
Keywords: ADSORPTION ISOTHERM; BLOCK CO-POLYMER; COMPLEMENT; NANOSPHERE; POLOXAMINE; SPLEEN
Document Type: Research Article
Publication date: September 1, 2006
More about this publication?
- Journal for Nanoscience and Nanotechnology (JNN) is an international and multidisciplinary peer-reviewed journal with a wide-ranging coverage, consolidating research activities in all areas of nanoscience and nanotechnology into a single and unique reference source. JNN is the first cross-disciplinary journal to publish original full research articles, rapid communications of important new scientific and technological findings, timely state-of-the-art reviews with author's photo and short biography, and current research news encompassing the fundamental and applied research in all disciplines of science, engineering and medicine.
- Editorial Board
- Information for Authors
- Subscribe to this Title
- Terms & Conditions
- Ingenta Connect is not responsible for the content or availability of external websites
- Access Key
- Free content
- Partial Free content
- New content
- Open access content
- Partial Open access content
- Subscribed content
- Partial Subscribed content
- Free trial content