Silk nanospheres and microspheres from silk/pva blend films for drug delivery

Abstract

Silk fibroin protein-based micro-and nanospheres provide new options for drug delivery due to their biocompatibility, biodegradability and their tunable drug loading and release properties. In the present study, we report a new aqueous-based preparation method for silk spheres with controllable sphere size and shape. The preparation was based on phase separation between silk fibroin and polyvinyl alcohol (PVA) at a weight ratio of 1/1 and 1/4. Water-insoluble silk spheres were easily obtained from the blend in a three step process: (1) air-drying the blend solution into a film, (2) film dissolution in water and (3) removal of residual PVA by subsequent centrifugation. In both cases, the spheres had approximately 30% beta-sheet content and less than 5% residual PVA. Spindleshaped silk particles, as opposed to the spherical particles formed above, were obtained by stretching the blend films before dissolving in water. Compared to the 1/1 ratio sample, the silk spheres prepared from the 1/4 ratio sample showed a more homogeneous size distribution ranging from 300 nm up to 20 μm. Further studies showed that sphere size and polydispersity could be controlled either by changing the concentration of silk and PVA or by applying ultrasonication on the blend solution. Drug loading was achieved by mixing model drugs in the original silk solution. The distribution and loading efficiency of the drug molecules in silk spheres depended on their hydrophobicity and charge, resulting in different drug release profiles. The entire fabrication procedure could be completed within one day. The only chemical used in the preparation except water was PVA, an FDA-approved ingredient in drug formulations. Silk micro-and nanospheres reported have potential as drug delivery carriers in a variety of biomedical applications.

Ultra‐Thin Hollow Carbon Nanospheres for Pseudocapacitive Sodium‐Ion Storage

“…[30] It can be dissolved and easily reformed into various morphologies resulting from self-assembly. [31][32][33][34][35] This recombined silk fibroin (RSF) can be further transformed into a nanostructured, nitrogen-doped, carbon-based material via a simple pyrolysis process. [5] The fabrication process of the UTH-CNs is shown in Figure 1.…”

Keratin/Polyvinyl Alcohol Blend Films Cross-Linked by Dialdehyde Starch and Their Potential Application for Drug Release

“…PVA is a nontoxic, biodegradable, synthetic, water-soluble polymer with outstanding chemical stability and good film-forming capacity [18,19]. PVA-protein films are produced as materials for food packing, tissue engineering, and drug delivery systems [20][21][22][23]. PVA hydrogel materials containing keratin from wool and hair were recently synthesized by electron beam irradiation [24].…”

Synthesis and Properties of Silk Fibroin/Konjac Glucomannan Blend Beads

“…The experiments involved three steps: (1) vaporization and removal of moisture in beads (to 100 °C), (2) material decomposition (at a different range for each case), and (3) thermal degradation and carbonization of the compounds (375 °C for all cases). In the case of SF samples, they presented a loss mass related to the breakdown of peptide bonds and side-chains of the residual amino acids [14,36].…”

“…However, to be successfully used these materials should be modified to improve different properties, such as in-vivo stability, biocompatibility, biodegradability, and potential interaction with cells. For that, the scaffolds should also have a cell-friendly surface, and interconnected pores for the transport of cells, nutrients, and metabolites [2].…”