New Material: Electrospinning Mixes Incompatible Ingredients Into A Nanofiber

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Russian researchers from the Federal Center for clinical research in physical and chemical medicine, the Moscow Institute of physical technology and Lomonosov Moscow State University have shown that two incompatible components (a protein and a polymer) may be mixed into an electrospun fiber. The study, also published in the journal RSC progress, also showed that the resulting pads could gradually release protein. Protein containing composite mats are expected to be used in biomedical applications, such as burn and wound dressings, matrix for drug delivery and release, and tissue engineering.

　 Electrospinning

Electrospun mats made of superfine fibers have many applications. They can be used in protective clothing, antibacterial wound dressings, liquid and gas filtration in tissue engineering, cell culture, drug delivery, as adsorbents and catalytic substrates.

Electrospinning is a method for manufacturing microfibers and nanofibers from polymers, involving the use of electrostatic fields. At high pressures of about 20 kV, once the Coulomb repulsion overcomes the surface tension, a drop of polymer solution becomes charged and stretches into fine fibers.

The technology is quite flexible and can be incorporated into electrospun pads: micron and nano particles with different properties, carbon nanotubes, fluorescent dyes, drugs and antibacterial agents, polymer and biopolymer mixtures. In this way, the characteristics of the mat can be fine tuned to suit the specific practical application.

　　 High molecular protein pad

Electrospun pads are usually made of carrier polymers to ensure stable fiber formation and to allow for the addition of other components. For biomedical applications, biodegradable and biocompatible polymers are usually needed, and polylactic acid is one of the most common polymers. PLA is used to produce biodegradable packaging, surgical threads, screws and pins.

The main problem in the use of PLA in biology and medicine is its hydrophobicity, so the cell adhesion is poor. To solve this problem, polymers are mixed with proteins because they are non-toxic, hydrophilic, naturally metabolized and can act as therapeutic agents.

The researchers studied a mixture of water-insoluble PLA and water-soluble globular proteins called bovine serum albumin or BSA. Experiments in aqueous media show that the protein components will gradually release from the mat into the solution. Specifically, about half of the protein is dissolved in a week. This effect suggests that it may be used in prolonging the release of protein based drugs.

In order to predict the performance of the mixing pad, the team had to study the protein distribution in it. It should be noted that most polymers do not mix well. In the polymer protein solvent system, the components tend to separate into two solutions. Although this does apply to PLA and BSA solutions, electrospinning enables researchers to overcome phase separation in the mat. Using three independent analytical methods, they showed that both components were present in each fiber (Figure 1): fluorescence microscope, EDX spectrum and Raman spectrum.

　　 "Electrospun polymer protein hybrid mats have many potential applications. By changing the amount of protein, you can adjust the rate of mat biodegradation. The numerous functional groups of the protein enable us to modify chemical compounds by attaching them to the surface of the mat. Protein based blend mats can also be used as a selective filter or to extend drug release time, for example Such as in burns and wound dressings. " Dmitry klinov, co-author of the study, commented. He is a researcher in the Department of molecular and translational medicine of MIPT and head of the medical Nanotechnology Laboratory of the federal research clinical center of physical and chemical medicine of the Russian federal medical and biological Bureau.