Dextran microspheres preparation

Polyelectrolyte multilayer microspheres, prepared by alternating adsorption of dextran sulfate and protamine on melamine formaldehyde cores followed by the partial decomposition of the core, were used to immobilise the peroxidase and glucose oxidase. Retention of enzymic activity of the peroxidase/glucose oxidase system incorporated into the microspheres was demonstrated. These bienzyme system immobilised in the microspheres can be applied for kinetic glucose assays [ 156]. 

Stenekes RJH, Franssen O, van Bommel EMG, Crommelin DJA, Hennink WE. The preparation of dextran microspheres in an all aqueous system effect of the formulation parameters on particle characteristics. Pharm Res 1998 15 557-561. 

Microspheres and nanoparticles often consist of biocompatible polymers and belong either to the soluble or the particle type carriers. Besides the aforementioned HPMA polymeric backbone, carriers have also been prepared using dextrans, ficoll, sepharose or poly-L-lysine as the main carrier body. More recently alginate nanoparticles have been described for the targeting of antisense oligonucleotides [28]. As with other polymeric carrier systems, the backbone can be modified with e.g. sugar molecules or antibody fragments to introduce cellular specificity. 

Activation, dextran and inulin, 189-195 Activation energy of diffusion, 50-52 Additives, effect on percutaneous absorption of drugs in rabbits, 275 Agarose gel, use in liposomal drug delivery system, 267-270 Albumin microspheres intramuscular and intraarticular drug delivery, 204,206,211 preparation, 204,207/... 

Cobalt nanoparticles (surface modified with L-cysteine ethyl ester) ethanol wet are available as 10mn black powder (wet with EtOH) which is best used within 3 months. The material can be easily transferred into stable aqueous suspensions, and can be used as a starting material for surface modifications (e.g. dextran coating) or the preparation of magnetic polymer microspheres. 

The preparation of loaded CaC03 microspheres was carried out according to the co-precipitation method [20,21]. To prepare the CaCOj microspheres loaded with SNARF-1 dextran were nsed 1.6 ml H O, 0.5 ml IM CaClj, 0.5 ml IM Na COj and 0.4 ml SNARF-1 dextran solntion (1 mg/ml). 

To prepare the CaCO microspheres contained different ratio of SNARF-1 dextran and urease were used ... 

The preparation of loaded CaCO microspheres was carried out according to the coprecipitation-method [20, 21], To prepare the CaC03 microspheres loaded with SNARF-1 dextranwere used 1.6 mLHjO, 0.5 mL 1 M CaCl, 0.5 mL 1 MNa COj and 0.4 mL SNARF-1 dextran solution (1 mg/mL). 

Chen F, Wu Z, Wang Q. et al. Preparation and biological characteristics of recombinant human bone morphogenetic protein-2-loaded dextran-co-gelatin hydrogel microspheres, in vitro and in vivo studies. Pharmacology 2005 75 133-44. 

Figures 4, 5 and 13 show the release of proteins form macroscopic dextran-based hydrogels. For therapeutic applications of these protein-loaded gels, injectable dosage forms like microspheres are preferred. Extensive research has been done so far on the preparation of microspheres based on biodegradable polymers (e.g. PLGA). However, for the preparation of these microspheres, organic solvents are used which might cause denaturation of the encapsulated protein (see Introduction). Furthermore, the use of organic solvents has environmental and clinical drawbacks.

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