Dr Seishi Shimizu

01904 328281
E-mail: seishi.shimizu@york.ac.uk

Statistical thermodynamics of complex fluids: towards a rational approach to formulation

Solvents are crucial in all chemical, biotechnological, pharmaceutical, biomaterials and food industries: 

  • Solubilizing key ingredients is central to product formulation and chemical processes.
  • Yet choosing appropriate solvents (or mixtures) often requires extensive trials and errors and is costly.
  • Biomolecules exploit solvation for their stability and function.

To exploit solvation to the full, we need to understand its molecular mechanism:

  • Solvents associate with solutes in a non-specific and dynamic manner
  • Traditional approaches (such as solvent binding model) do not work
  • Statistical thermodynamics bridging molecular world with ours is the only reliable guideline from physics laws

Routine experimental data can be surprisingly informative on how molecules work, when assisted by theory:

  • Solubilization mechanism can be revealed only from solubility, density and osmotic data
  • Why some additives (cosolvents, hydrotropes, entrainers) dramatically increase solubility has been revealed
  • How biomolecular stability is affected by osmolytes or flavour molecules can directly come from calorimetry data

To make this possible, we work on:

  • Fundamental theory of solvation, adsorption and colloidal interactions using pen and paper
  • Experimental work on solubility, densitometry, neutron scattering and biomolecular stability in collaboration with experimentalists
  • Industrial collaborations on specific questions

Our present target areas are:

  • Hydrotropy and solubilization
  • Protein stability and denaturation
  • Cellulose dissolution and biomass exploitation
  • Colloids, surfactants and interface
  • Food science

To find out more, our recent reviews would be useful:

  • A general theory of hydrotropy: Shimizu & Matubayasi, Phys. Chem. Chem. Phys. 2017, 19, 23597.
  • Green solution chemistry: Abbott, Booth & Shimizu, Green Chem. 2017, 19, 68-75.
  • “Gastrophysics” - food gels and protein stability: Shimizu, Stenner & Matubayasi, Food Hydrocoll. 2017, 62, 128-139.
  • Food flavour: Shimizu, Abbott & Matubayasi, Food & Function, 2017, 8, 2999-3009.

Selected Publications

  • Hydrotropy and scattering: pre-ouzo as extended near-spinodal region
    S Shimizu and N Matubayasi, Phys Chem Chem Phys, 2017, 19, 26734-26742
  • Unifying hydrotropy under Gibbs phase rule
    S Shimizu and N Matubayasi, Phys Chem Chem Phys, 2017, 19, 23597-23605 
  • The origin of cooperative solubilisation by hydrotropes
    S Shimizu and N Matubayasi, Phys Chem Chem Phys, 2016, 18, 25621-25628 
  • Origin of nonlinearity in phase solubility: Solubilisation by cyclodextrin beyond stoichiometric complexation
    T W J Nicol, N Matubayasi and S Shimizu, Phys Chem Chem Phys, 2016, 18, 15205-16217
  • Hydrotrope accumulation around the drug: The driving force for solubilization and minimum hydrotrope concentration for nicotinamide and urea
    J J Booth, M Omar, S Abbott and S Shimizu, Phys Chem Chem Phys, 2015, 17, 8028-8037
  • Subnanoscale hydrophobic modulation of salt bridges in aqueous media
    S Chen, Y Itoh, T Masuda, S Shimizu, J Zhao, J Ma, S Nakamura, K Okuro, H Noguchi, K Uosaki and T Aida, Science, 2015, 348, 555-559
  • Preferential Solvation: Dividing surface vs excess numbers
    S Shimizu and N Matubayasi, J Phys Chem B, 2014, 118, 3922-3930.
  • Hydrotropy: Monomer–micelle equilibrium and minimum hydrotrope concentration
    S Shimizu and N Matubayasi, J Phys Chem B, 2014, 118, 10515-10524.
  • The Mechanism of Hydrophobic Drug Solubilization by Small Molecule Hydrotropes
    J J Booth, S Abbott and S Shimizu, J Phys Chem B, 2012, 116, 14915–14921.
  • Estimating hydration changes upon biomolecular reactions from osmotic stress, high pressure, and preferential hydration experiments
    S Shimizu, Proc Natl Acad Sci USA, 2004, 101, 1195-1199.