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With the recent innovations in nanofabrication, the use of a customizable bioparticle allows for many specified uses previously unimaginable for researchers. Highly sensitive purification, functional group modification or protection, and localized sensing are just a few specific applications that can be achieved using a customized bioparticle.

Free PDF guide:   "Validation of Magnetic Bead Separation Processes" 

A polymeric nano polymer consists of a polymer matrix, which can come in a variety of shapes, such as a sphere or rod, depending on the application. This polymeric matrix is then filled with a substance. For purification applications, the nanopolymer can be designed to store the desired product to be purified. For drug delivery methods, the nanopolymer can be used to store a specific drug. Generally speaking, the radius or dimensions of the particle are in the range of 1-50 nm, with some exceptions. It is also worth acknowledging that some manufactures define different sizes for nanoparticles, and there has not been a specifically defined size to fit this range. However, it is clearly defined that the transition from micro sized nanopolymers, which range from 50 nm into the micrometer size, allows for a large increase in surface area to volume ratio, enabling behavior depending upon surface area instead of diffusion rates. Thus, polymeric nanoparticles do not rely on the rate of diffusion for their application. 

Generally speaking, polymeric nanoparticles are separated into two categories: nanocapsules, and nanospheres. Nanocapsules are noted for having a less rigid surface, whereas nanospheres are rigid, solid structures. As a result, different strategies have emerged for their use. Nanocapsules generally carry proteins or drugs that are lipid or aqueous soluble, with delivery to a specified region, and act as individual molecules. Nanospheres, by comparison, cross link with one another, and are generally better suited for purification instead of molecular delivery. They can also be synthesized with a surface charge to directly conjugated molecules of specific charge or affinity. 

Nanopolymer Synthesis

Due to the versatile nature of polymeric bioparticles, there are numerous methods for synthesis. This depends on the structure of the particle and its desired properties. One method (solvent evaporation) involves using volatile organic solvents such as dichloromethane and chloroform, where the polymer is sonicated while the solvent evaporates out, resulting in polymer bonds forming. Another method (salting out) uses surfactants that prevent the polymers from being stable in solution and therefore link to one another. Polymers can also be precipitated out by quickly depositing the polymer into an oversaturated solvent, forcing the polymer to bond with itself. Many other synthetic methods have been designed depending on the application of this vast process.  

Application – Drug Delivery

One really exciting type of nano polymer is called a nanosponge, which falls within the nanocapsule subcategory. A small polymer is filled with some type of drug, often a chemotoxin, which is administered throughout the whole body in chemotherapy. In this instance, the nanosponge is accompanied with a biological tag that is designed to specifically interact with corresponding DNA sequences, which correspond to mutated cancer cells throughout the body. Nanosponges do not interact within the body, but upon cellular interaction with the nanosponge, they release chemotoxins to the cell that allow for directed targeting of cancer, and eliminates the awful side effects of chemotherapy. 

Enhancing of Nanopolymers using Magnetic Separation

There are various cases where nanoparticles built with superparamagnetic properties (i.e. built with magnetite core) can improve their efficiency as carriers using the right biomagnetic separation system. The application of a magnetic field magnetizes the composite, so one could easily purify a substance using nanoparticles and, when it is removed, then quickly have the particles disperse the desired analyte  (superparamagnetism implies no residual magnetic moment when it is not magnetic field). This would save researchers time and money as they would not need to utilize various solvents to have the nanoparticles release the analyte. In cases of a nanosphere with a surface charge, different magnetic forces could be utilized to conjugate specific analytes of interest, allowing for purification of multiple products with a single nanopolymer. 

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Lluis M. Martínez | SEPMAG Chief Scientific Officer

Founder of SEPMAG, Lluis holds a PhD in Magnetic Materials by the UAB. He has conducted research at German and Spanish academic institutions. Having worked in companies in Ireland, USA and Spain, he has more than 20 years of experience applying magnetic materials and sensors to industrial products and processes. He has filed several international patents on the field and co-authored more than 20 scientific papers, most of them on the subject of magnetic particle movement.

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