Microspheres Online

Everything about microspheres and research utilizing precision spherical particles.

Chitosan Coated PLGA-Microspheres – A Modular System for Targeted Drug Delivery

During some research on PLGA microspheres we found this interesting article published in European Cells and Materials Vol 7 Suppl 2. 2004 (pages 11-12).?? They were able to achieve a significant change in the zeta potential of their microspheres just by increasing the dosage of Chitosan.?? The authors conclusions and a graph of their data follow.

Discussion and Conclusions by the authors:

The increase in zeta potential from ?70.8 mV (chitosan-free PLGA particles) to +20.5 mV with increasing chitosan concentrations in the W2-phase used for particle preparation strongly suggests that the polycationic chitosan was firmly adsorbed to the particle surface. This finding was confirmed by X-ray photoelectron spectroscopy (data not shown). The coupling of biotin via a NHS-PEGlinker showed that the amino groups of? chitosan represent suitable sites for covalent bioconjugation of different ligands. The process allows the production of particles with a mean diameter between 1 and 10 um, a useful size range for the phagocytosis by? phagocytes like dendritic cells or macrophages.

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Biodegradable microspheres for vitreoretinal drug delivery

One of the microsphere topics that seems to be growing these days is biodegradability.? For those of you who are unfamiliar with the topic an excellent introductory article can be found in: Advance Drug Delivery Reviews 52 (2001) 5-16, called “Biodegradable microspheres for vitreoretinal drug delivery.”? The article does a good job describing the advantages of the various polymers available, such as poly(lactic acid) [PLA], poly(glycolic acid) [PGA], and its copolymer poly(lactic-coglycolic) acid [PLGA].

The article also recommends the prefered sterlization method for drug delivery (the authors recommend irradiation).

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Exfoliating Beads: Clinical Study

Exfoliating beads have a long history in cosmetics, but we are unaware of previous studies on the effect of their regular use. A clinical study with 10 subjects shows that regular exfoliation leads to a reduction in the cell turnover time of the stratum corneum (SC) by about 15% (significant at the 95% level)

What is a Microsphere? Definition and Explanation.

Sourcing Microspheres - Monodisperse Silica
Conductive Bondline Spacer - Silver-Coated Silica Spheres
Conductive Bondline Spacer – Silver-Coated Silica Microspheres (Cospheric Product ID: SiO2MS-Ag)

Definition of a Microsphere:

There is a lot of confusion and uncertainty in the academic community as well as the industry on exactly what is a microsphere. Below is the definition of “microsphere” that we use, because it is clear and straight-forward:

Microsphere is a term used for a small solid spherical particle, with diameter in the micrometer range (typically 1 micron to 1000 micron (1mm)).

What a Microsphere is Not:

A microsphere is not the same as a microcapsule, because microcapsules typically consist of a flexible (deformable) shell encapsulating a fluid, which might be liquid or gas. Microspheres always have a solid shell. Even if the microsphere is technically hollow (containing gas inside), its shape is not significantly flexible or deformable.

A microsphere is not the same as a microparticle, because microparticle is a general term that refers only to the size of the granular material and does not provide information on the shape. Microspheres are always round and spherical. There are no sharp edges, oblong shapes, or debris.

What are Nanospheres? Silica Nanospheres
Monodisperse Silica Nanospheres (Cospheric Product ID: SiO2MS)

A microsphere is not the same as a nanopshere, because nanospheres have diameters on the nanoscale (typically between 1 nanometer and 1000 nanometers (1 micron)). Nano-diameters present a complete different characteristics, behaviors, and functionalities.

What are Microsphere Materials:

Microspheres are manufactured from various natural and synthetic materials. Glass microspheres, polymer microspheres, and ceramic microspheres are commercially available. Solid and hollow microspheres vary a lot in density and, therefore, are used for different applications. Hollow microspheres are typically used as additives to lower the density of a material. Solid microspheres have numerous applications depending on what material they are constructed of and what size they are.

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