Microspheres in Drug Delivery Systems – 2 Essential Uses

Polystyrene Microspheres

Benefits of Microspheres in Drug Delivery There are numerous benefits of using microspheres in drug delivery due to their precise uniform dimensions, larger surface area per unit volume, as well as the ability to be surface-functioalized or loaded with active compounds and other additives. Typically microspheres in drug delivery are manufactured out of biodegradable materials … Read more

Black Paramagnetic Spheres and Micropsheres 10micron to 1.4mm

Black Paramagnetic Microspheres

Black polyethylene paramagnetic microspheres are now available in wide selection of particle sizes ranging from 10 micron to 1.4 millimeters. The particles are supplied in dry powder form. No solvents are used in the manufacturing process. Black paramagnetic polymer microspheres have a strong response to magnetic fields and can be manipulated with a magnet. Highly … Read more

Custom Janus Particles, Microspheres, Microbeads – Bichromal Particles

Custom Janus Particles - Ceramic

What are Custom Janus Particles? Janus particle is anisotropic and refers to a particle, typically of spherical shape, with two hemispheres which may vary in color, optical properties, surface tension, electrostatic charge, magnetic response, conductivity, fluorescence, reflectivity and more. Custom Janus Particles Manufacturing Cospheric LLC uses a patented process to offer a unique capability of … Read more

Negatively-charged Yellow Microparticles – Back in Stock

Cospheric’s neutrally-buoyant highly charged yellow microspheres have a strong negative charge and are used by scientists in medical technology, biotechnology, applied physics and research. Precise particles with known density of 1.0g/cc that behave in a known way are useful as a model particles in simulation experiments.? Particles in a range of diameters from 5micron to … Read more

BioCompatability of Metal Coated Spheres

For those scientists?who are looking to use silver coated materials?such as silver coated microspheres in biomedical applications, it is important to understand whether they are bio-compatable.? A selection of abstracts and article references related to the biocompatability of silver follow:

The Biocompatibility of Silver2

The experiments reported have referred to some of the characteristics of the biocompatibility of Ag. Silver has been shown to display interactions with albumin, as an example of a plasma protein, quite different from those of most metals. Such studies shed further light on the complex issue of protein adsorption on biomaterials. It has also been demonstrated that Ag at concentrations < 1 ppm exerts a considerable influence on the activity of lactate dehydrogenase, this effect being reversed in the presence of albumin. A significant but transient increase in blood levels of Ag following intramuscular implantation of the metal has been observed. This is not reflected in any raised urine level. It is proposed that the richly vascular tissue immediately surrounding the implant in the acute phase of the response gives rise to the transient increase, but a subsequent decrease in vascularity reduces this possibility. It appears that Ag released from implants following this initial period substantially remains in the local area.2

Lack of toxicologocial side-effects in silver-coated megaprostheses in humans1

Deep infection of megaprostheses remains a serious complication in orthopedic tumor surgery. Furthermore, reinfection gets a raising problem in revision surgery of patients suffering from infections associated with primary endoprosthetic replacement of the knee and hip joint. These patients will need many revision surgeries and in some cases even an amputation is inevitable. Silver-coated medical devices proved their effectiveness on reducing infections, but toxic side-effects concerning some silver applications have been described as well. Our study reports about a silver-coated megaprosthesis for the first time and can exclude side-effects of silver-coated orthopedic implants in humans. The silver-levels in the blood did not exceed 56.4 parts per billion (ppb) and can be considered as non-toxic. Additionally we could exclude significant changes in liver and kidney functions measured by laboratory values. Histopathologic examination of the periprosthetic environment in two patients showed no signs of foreign body granulomas or chronic inflammation, despite distant effective silver concentrations up to 1626 ppb directly related to the prosthetic surface. In conclusion the silver-coated megaprosthesis allowed a release of silver without showing any local or systemic side-effects.1

Specific Article?References for the biocompatability of silver are below:

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Patent Review: Use of Adsorbent Carbon Microspheres for Treatment of Irritable Bowel Syndrome

One embodiment disclosed herein includes a method of treating one or more symptoms of irritable bowel syndrome by administering to the subject adsorbent carbon microspheres with a particle size of 0.01mm to about 2 mm to reduce the abdominal discomfort or pain. In one embodiment, the amount of the adsorbent carbon microspheres is sufficient to achieve at least about a 50% reduction in the number of days the subject experiences abdominal pain or discomfort.

Patent Review: Preparation of Swellable and Deformable Microspheres

United States Patent number 7,794,755 was issued on September 14, 2010, describing the process for preparation of swellable and deformable microspheres. The patent is assigned to E.I. du Pont de Nemours and cites Figuly, Mahajan, and Schiffino as inventors.

Motivations for Using Biodegradable Microspheres in Drug Delivery

In recent years there is significant interest in using biodegradable polymeric microspheres for drug delivery. Delivering drugs through biodegradable microspheres has numerous advantages compared to conventional delivery systems. While in conventional systems the drug is usually released shortly after delivery and stops working after a brief period of time, biodegradable polymer offers a way to provide sustained release over a longer time, thus eliminating the need for multiple doses and ensuring sustained and controlled drug delivery over weeks or months.

Dual nanocomposite multihollow polymer microspheres prepared by suspension polymerization based on a multiple pickering emulsion

Excerpts from an interesting approach to creating hollow polymer microspheres from a pickering emulsion.

Abstract:

A solid-stabilized multiple w/o/w or o/w/o emulsion was prepared in a two-step process. Various nanocomposite polymer microspheres with multihollow armored closed pores were fabricated easily by suspension polymerization of the multiple Pickering stabilized emulsions.

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Chitosan microspheres prepared by spray drying

Spray drying has been used in the production of fine powders from emulsions for many years, but it is not a process in which most people associate the production of microspheres.? This journal article shows how the authors were able to produce highly spherical microspheres in the 2-10um range by controlling the levels of Chitosan and crosslinking agents used.

Chitosan MicrospheresThe key items I found of interest in this article were:

The quality of the microspheres that were produced, as seen the the attached SEM micrograph.

How the process variables did not affect the zeta potential of the microspheres produced (Table 4 below), and how the size can be varied by varying the concentrations of Chitosan or the Molecular weight (MW).

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