Polymer- und liposomstabilisierte Ferrofluide und ihre Funktionalisierung

This work deals with the preparation of 10 nm, 13 nm and 130 nm sized Fe3O4 crystallites. The 10 nm and 13 nm sized Fe3O4 crystallites are superparamagnetic and therefore subdomain particles. Their specific heat absorption rates from high frequency alternating magnetic fields are 20 times higher (50-65 W/ g Fe3O4) compared to those of multidomain Fe3O4 particles (3 W/ g Fe3O4). Colloidal suspensions of the 13 nm sized Fe3O4 particles are formed by a procedure, which includes a probe sonication step. The polymers alginate and polyacrylate used for stabi-lisation bear carboxylate groups. The procedure results in a fraction of relatively large sized (250-1100 nm) and another one with considerable smaller sized (50-180 nm) polymerstabili-sed particles (PSM). Because of the carboxylate groups on their surface, the larger sized PSM may be suitable for removing Ni2+ ions from waste water. Specific binding capacities up to 40 and 170 nmol Ni2+/mg Fe3O4 are determined for alginate- and polyacrylatestabilised particles respectively. The smaller sized PSM are of interest for in vivo applications, e.g. for "targeted drug delivery". Furthermore, liposomestabilized magnetic particles (LipoM) are modified by chemical means with regard to future medical applications. First, a phospholipid polyethylen glycol deriva-tive (DCxPE-PEG-biotin) is synthesized. Vesicles or LipoM with embedded DCxPE-PEG-biotin have prolonged blood circulation times compared to classical LipoM which bear no PEG chains. The biotin groups can bind (strept)avidinylated biomolecules, such as monoclo-nal antibodies required for "targeted drug delivery", very tightly to the LipoM surface (biotin-avidin binding). This is demonstrated with streptavidinylated alkaline phosphatase as a model protein, whose enzymatic activity can be readily monitored spectrophotometrically. With regard to the use of LipoM for "targeted drug delivery" the DCxPE-PEG-biotin must be firmly anchored in the lipidic envelope. The transfer experiments reveal, that the firmness of the anchoring is strongly influenced by the PEG-biotin moiety and the fatty acyl chain length of the molecule and the physical state ("gel" or "liquid-crystalline" state) of the vesicle. DC18:0PE-PEG-biotin ist firmly anchored in "gel-like" vesicles and subsequently this molecule meets all requirements for the preparation of vesicles for use in "targeted drug delivery".

Grantor dc:publisher

Publikationsserver der RWTH Aachen University

Year dc:date

2002

Author dc:creator

• Hodenius, Michael

Contributors dc:contributor

• Lueken, Heiko

• info:eu-repo/classification/ddc/540
• Chemie

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

ger

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-119133%22

OAI identifier oai:identifier

oai:publications.rwth-aachen.de:57064