Biomedical subjects

M Schnabelrauch

Publications and source records attributed to M Schnabelrauch.

7 recordsLinked to original sources

PubMed2006

Differential interaction of magnetic nanoparticles with tumor cells and peripheral blood cells.

PURPOSE: The separation of tumor cells from healthy cells is a vital problem in oncology and hematology, especially from peripheral blood. Magnetic assisted cell sorting (MACS) is a possibility to fulfill these needs. METHODS: Tumor cell lines and leukocytes from peripheral blood were incubated with carboxymethyl dextran-coated magnetic nanoparticles under various conditions and separated by MACS. RESULTS: We studied the interaction of magnetic nanoparticles devoid of antibodies with healthy and tumor cells. The magnetic nanoparticles interact with tumor cells and leukocytes and are located predominantly within the cell cytoplasm. Incubation of cell culture cells with magnetic nanoparticles led to a labeling of these cells without reduced biological properties for at least 14 days. The interaction of the magnetic nanoparticles with cells depends on several factors. The ionic strength (osmolality) of the solvent plays an important role. We could show that an increase in osmolality led to a dramatic reduction of labeled leukocytes. Tumor cells, however, are mildly affected. This could be detected not only in pure cultures of tumor cells or leukocytes but also in mixed cell populations. CONCLUSION: This observation gives us the opportunity to selectively label and separate tumor cells but not leukocytes from the peripheral blood.

Blood Cells↗

PubMed2005

Design of oligolactone-based scaffolds for bone tissue engineering.

Novel difunctional oligolactone macromers have been synthesized by ring-opening oligomerization of various lactones (L-lactide, glycolide, p-dioxanone) in the presence of suitable diols (propane-1,2-diol, dianhydro-D-glucitol) and subsequent endcapping of the formed oligolactones with methacrylate moieties. Based on these macromers, two fabrication procedures were developed to fabricate highly porous scaffolds and the material properties including in vitro biodegradation behaviour of the resulting polymeric scaffolds were investigated. Preliminary in vitro studies on the cytocompatibility of the fabricated scaffolds and on osteoblast cultivation on the optimized polymeric materials demonstrated that the oligolactide based polymer networks possess an excellent biocompatibility and that they are promising candidates as scaffolds in bone tissue engineering.

3T3 Cells↗

PubMed2002

Fabrication of highly porous scaffold materials based on functionalized oligolactides and preliminary results on their use in bone tissue engineering.

Tissue engineering offers a promising new approach to repair bone defects. Its practical realisation is connected with the development of suitable scaffold materials. In the present work, functionalized oligolactides have been prepared and used as macromers for the scaffold fabrication The developed fabrication process leads to highly porous scaffolds, available in various shapes and sizes, with an open inter-connective pore structure and porosities up to 90%. Degradable or even osteoconductive components as well as biocompatible co-monomers can be used as additives to modulate the scaffold properties. Under in vitro conditions, the scaffolds exhibit a continuous degradation with varying degradation rates depending on their material composition. In vitro studies on the cultivation of osteoblasts on the scaffolds were performed and revealed their excellent biocompatibility. Cell growth on the scaffold surfaces and inside the scaffolds, formation of extracellular matrix and starting mineralization were detected by microscopical and histological analyses. Based on these results the developed materials are well-suited candidates for the design of tailor-made matrices in bone tissue engineering

Journal Article↗

PubMed2002

New synthetic siderophores and their beta-lactam conjugates based on diamino acids and dipeptides.

Linking of siderophores to antibiotics improves the penetration and therefore increases the antibacterial activity of the antibiotics. We synthesized the acylated catecholates and hydroxamates as siderophore components for antibiotic conjugates to reduce side effects of unprotected catecholate and hydroxamate moieties. In this paper, we report on bis- and tris-catecholates and mixed catecholate hydroxamates based on diamino acids or dipeptides. These compounds were active as siderophores in a growth promotion assay under iron limitation. Most of the conjugates with beta-lactams showed high in vitro activity against Gram-negative bacteria especially Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, Serratia marcescens and Stenotrophomonas maltophilia. The compounds with enhanced antibacterial activity use active iron uptake routes to penetrate the bacterial outer membrane barrier, demonstrated by assays with mutants deficient in components of the iron transport system. Correlation between chemical structure and biological activity was studied.

Amino Acids, Diamino↗

PubMed2001

New artificial siderophores based on a monosaccharide scaffold.

New artificial catecholate siderophores with methyl alpha-D-glucopyranoside as scaffold were synthesized. The dihydroxy- or di(acetoxy)benzoyl moieties were attached either directly or via aminopropyl spacer groups, to the carbohydrate scaffold. The siderophore activity of the prepared siderophore analogs was examined by a growth promotion assay using various Gram-negative bacteria and mycobacteria and by the CAS-assay.

Gram-Negative Bacteria↗

PubMed2000

New synthetic catecholate-type siderophores based on amino acids and dipeptides.

New analogs of bacterial siderophores with one, two or three catecholate moieties were synthesized using various mono- and diamino acid and dipetide scaffolds, respectively. In addition to 2,3-dihydroxybenzoyl siderophore analogs and their acylated derivatives, 3,4-dihydroxybenzoyl derivatives were prepared. Furthermore, the synthesis of a new triscatecholate serving as an intimate model for enterobactin is reported. Most of the new compounds gave a positive CAS-test and were active as siderophores tested by growth promotion assays with a set of siderophore indicator mutants under iron limitation. Structure-activity-correlations have also been studied.

Amino Acids↗

PubMed1998

Novel catecholate-type siderophore analogs based on a myo-inositol scaffold.

A novel 1,3,5-triamino-myo-inositol derivative is presented as a readily available scaffold for the design of tripodal siderophore mimetics. Based on this scaffold, various hexadentate catecholate-type siderophore analogs were synthesized by attaching the catechols to the inositol scaffold via spacer units of different structure and length. The potential to tune the polarity of the inositol containing siderophore analogs has also been demonstrated by varying the protection group strategy. The siderophore activity of the prepared siderophore analogs was examined by cross-feeding tests with various Gram-negative bacteria and mycobacteria.

Catechols↗