Keiichi Yoshimatsu

Publications (2)17.98 Total impact

• Article: The Polymer Nanoparticle-Protein Interface. Evaluation of the Contribution of Positively Charged Functional Groups to Protein Affinity.

  Yusuke Yonamine, Keiichi Yoshimatsu, Shih-Hui Lee, Yu Hoshino, Yoshio Okahata, Kenneth J Shea
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  ABSTRACT: Cationic functionalized polymer nanoparticles (NPs) show strikingly distinct affinities to proteins depending on the nature of the cationic functional group. N-isopropylacrylamide (NIPAm) polymer nanoparticles (NPs) incorporating three types of positively charged functional groups (guanidinium, primary amino and quaternary ammonium groups) were prepared by precipitation polymerization. The affinities to fibrinogen, a protein with an isoelectric point (pI) of 5.5, were compared using UV-Vis spectrometry and a quartz crystal microbalance (QCM). Guanidinium-containing NPs showed the highest affinity to fibrinogen. The observation is attributed to strong, specific interactions with carboxylate groups on the protein surface. The affinity of the positively charged NPs to proteins with a range of pIs revealed that protein-NP affinity is due to a combination of ionic, hydrogen bonding and hydrophobic interactions. Protein affinity can be modulated by varying the composition of these functional monomers in the acrylamide NPs. Engineered NPs containing the guanidinium group with hydrophobic and hydrogen bonding functional groups were used in an affinity precipitation for the selective separation of fibrinogen from a plasma protein mixture. Circular dichroism (CD) revealed that the protein was not denatured in the process of binding or release.
  ACS Applied Materials & Interfaces 12/2012; · 4.53 Impact Factor
• Article: Temperature-responsive "catch and release" of proteins by using multifunctional polymer-based nanoparticles.

  Keiichi Yoshimatsu, Benjamin K Lesel, Yusuke Yonamine, John M Beierle, Yu Hoshino, Kenneth J Shea
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  ABSTRACT: Catch me if you can: Multifunctional, polymer-based nanoparticles that are capable of temperature-responsive "catch-and-release" of a target protein have been synthesized. The process is reversible and does not denature the proteins. An optimized combination of functional monomers imparts binding selectivity toward a target protein over other proteins.
  Angewandte Chemie International Edition 03/2012; 51(10):2405-8. · 13.45 Impact Factor