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In This Article

  • Summary
  • Abstract
  • Introduction
  • Protocol
  • Representative Results
  • Discussion
  • Disclosures
  • Acknowledgements
  • Materials
  • References
  • Reprints and Permissions

Summary

This article presents a protocol for the production of protein-based nanoparticles that changes the hydrophobic surface to hydrophilic. The produced nanoparticle is an assembly of gliadin-cyanoacrylate diblock copolymers. Spray coating with the produced nanoparticle changes the surface of target material to a hydrophilic surface.

Abstract

This article presents a protocol for the production of protein-based nanoparticles that changes the hydrophobic surface to hydrophilic by a simple spray coating. These nanoparticles are produced by the polymerization reaction of alkyl cyanoacrylate on the surface of cereal protein (gliadin) molecules. Alkyl cyanoacrylate is a monomer that instantly polymerizes at RT when it is applied to the surface of materials. Its polymerization reaction is initiated by the trace amounts of weakly basic or nucleophilic species on the surface, including moisture. Once polymerized, the polymerized alkyl cyanoacrylates show a strong affinity with the object materials because nitrile groups are in the backbone of poly (alkyl cyanoacrylate). Proteins also work as initiator for this polymerization because they contain amine groups that can initiate the polymerization of cyanoacrylate. If aggregated protein is used as an initiator, protein aggregate is surrounded by the hydrophobic poly(alkyl cyanoacrylate) chains after the polymerization reaction of alkyl cyanoacrylate. By controlling the experimental condition, particles in the nanometer range are produced. The produced nanoparticles readily adsorb to the surface of most materials including glass, metals, plastics, wood, leather, and fabrics. When the surface of a material is sprayed with the produced nanoparticle suspension and rinsed with water, the micellar structure of nanoparticle changes its conformation, and the hydrophilic proteins are exposed to the air. As a result, the nanoparticle-coated surface changes to hydrophilic.

Introduction

The goal of this article is to show the protocol for the preparation of nanoparticle suspension that modifies the wetting property of materials by a simple spray. The presented nanoparticle suspension is made from alkyl cyanoacrylate1 and a cereal protein, gliadin2,3. During the manufacturing process, protein aggregates are formed in aqueous ethanol4. Subsequent reaction with monomer (alkyl cyanoacrylate) produces the nanoparticle that is comprised of a protein core surrounded by linear polymer chains [poly(alkyl cyanoacrylate)]5.

Poly(alkyl cyanoacrylate)s are biodegradable and have been used for....

Protocol

1. Defatting Commercial Gliadin

  1. Measure 150 ml of acetone with a graduated cylinder and pour into 250 ml Erlenmeyer flask.
    1. While stirring with a spin bar on a magnetic stirrer at RT, add 30 g of commercial gliadin powder. Seal the opening of flask with aluminum foil, and keep on stirring O/N in the hood.
  2. Filtrate the solution with a filter paper.
    1. Wash the filtrate with fresh acetone (ca. 50 ml). Let stand for 10 min to allow the acetone to drain.
    2. Transfer the filtrate together with the filter paper underneath to a large dish such as a cell culture square dish. Cover the whole dish with a large filt....

Representative Results

Nanoparticles can be prepared in various reaction conditions. Gliadin forms aggregate in broad range of ethanol content5. However, the size of aggregates needs to be as small as possible because an additional layer (i.e., polymerized ECA) will be added to this aggregate and this process will make the final size larger. If the final size of particle is too large, the particle will be unstable and will easily be precipitated. Therefore, 68% aqueous ethanol was chosen as .......

Discussion

There are several critical steps in the production of the nanoparticle suspension. If the purified gliadin contains impurities, the reaction with ECA will produce side products. Although these unwanted products can be removed from the reaction medium during the centrifugation stage, it lowers the yield of the major product. If the gliadin solution prepared during experimental step 2.3) does not show clear separation between supernatant and precipitate after two days, the solution needs to stand for longer time. Using fre.......

Disclosures

Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture. USDA is an equal opportunity provider and employer.

Acknowledgements

Thanks to Mr. Jason Adkins for expert technical assistance.

....

Materials

NameCompanyCatalog NumberComments
Ethyl cyanoacrylate (ECA) monomerK&R International (Laguna Niguel, CA)I-1605Any pure ECA can be used.
GliadinMGP Ingredients, Inc (Atchison, KS)Gift from the companyGliadin can be purchased from Sigma-Aldrich (cat #: G3375-25G). Instead of gliadin, any commercial  gluten can be used.
HClAnyAny reagent grade chemical can be used.
AcetoneAnyAny reagent grade chemical can be used.
MethanolAnyAny reagent grade chemical can be used.
Ethanol (100%)AnyAny reagent grade chemical can be used.
Filter paperAnyAny grade filter paper larger than 10 cm can be used.
Cell culture square dishAnyAny dish larger than 20 cm x 20 cm can be used.
Coffee grinderAnyAny coffee grinder can be used.
Rotary evaporatorAnyAny rotary evaporator can be used.
Freeze DryerAnyAny freeze dryer that can reach - 70°C can be used.
CentrifugeAnyAny centrifuge that can apply 1000 x g can be used.
Magnetic stirrerAnyAny magnetic stirrer that can turn spin bar to 1000 RPM can be used.
Dynamic Light Scattering (DLS)Brookhaven Instruments CorporationNanoBrook Omni Zeta Potential AnalyzerDLS from any company can be used.
Scanning Electron Microscope (SEM)Carl Zeiss Inc.Any SEM can be used.
Dynamic Contact Angle (DCA)Thermo Cahn InstrumentsAny DCA can be used.

References

  1. Vauthier, C., Dubernet, C., Fattal, E., Pinto-Alphandary, H., Couvreur, P. Poly(alkylcyanoacrylates) as biodegradable materials for biomedical applications. Adv. Drug Deliver. Rev. 55, 519-548 (2003).
  2. Wieser, H. Chemistry of gluten proteins.

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