Joel Kaar
Associate Professor
Chemical and Biological Engineering



Ph.D. (Chemical Engineering), University of Pittsburgh, 2007
B.S. (Chemical Engineering), University of Pittsburgh, 2001

Research Interests

Our research is broadly focused on the symbiotic interfacing of proteins, namely enzymes, and materials. Specifically, we are interested in developing novel functional materials and approaches to material synthesis that exploit the exquisite properties (specificity, catalytic activity, self-assembly) and natural diversity of proteins. Within the context of this focus, we are studying how the microenvironment of proteins at material interfaces impacts protein function. An understanding of the link between protein structure, activity, and molecular environment is a requisite for designing rational strategies for incorporating proteins into materials and, more broadly, using proteins in new ways. The work in our group has considerable implications towards the use of enzymes for green chemistries, which reduce pollution and energy costs and increase safety, the design of tissue scaffolds with improved regenerative properties, the creation of biopolymers that sense and destroy toxic agents, and the development of renewable energy technologies.

The study of proteins in non-natural solvent environments
As solvents for the enzymatic synthesis of functional monomers and polymers, ionic liquids (ILs; salts that are liquid at ambient temperatures) have highly attractive properties. Notable properties of ILs include thermal stability and nonexistent vapor pressure, which render ILs an environmentally attractive solution to polluting organic solvents. Additionally, ILs can be tailored to dissolve virtually any materials by interchanging the cation and anion and thus designed for a specific reaction system. However, despite intense interest in the use of ILs for anhydrous biocatalysis, very little is known about how ILs interact with enzymes. This has greatly hindered the application of ILs in enzymatic processes, which has, to date, met with only modest success. The limited success calls to question the broader utility of ILs with enzymes unless the mechanism of enzyme deactivation in ILs can be understood and reversed. 
The aim of this research area is to address the fundamental question of how ILs impact enzyme structure and dynamics at the molecular level. We are specifically interested in elucidating the propensity and manner in which cations and anions in families of ILs bind to sites on the surface of and destabilize enzymes, the impact of ILs on the folding states and active site plasticity of enzymes as a function of IL properties, and strategies to mediate enzyme-solvent interactions that inactivate enzymes in ILs. Ultimately, this work will enable the framework to fully realize the scope of feasible biocatalytic reactions in ILs.

Rational biomaterial synthesis
Combining the power of biology and the sophistication of polymers presents the potential to engender innovative materials. Protein-containing polymers can be prepared by reacting a prepolymer with a protein, resulting in multipoint covalent immobilization of the protein within the polymer network. To create biomaterials with enhanced functional properties, we are designing rational synthetic schemes that preserve the activity and control the supramolecular assembly of proteins in materials and which are scalable. In developing fundamental design principles, we are interested in resolving how the conformation of proteins and timescale of protein dynamics is perturbed upon incorporation into materials, the forces (chemical and structural) that destabilize proteins at material interfaces, and ubiquitous structural elements in proteins whose modification does not compromise protein function. Moreover, we are devising strategies to guide the spatial immobilization of proteins within materials, which enable complete control over material properties.

  • University of Colorado Provost’s Faculty Achievement Award, 2016
  • University of Colorado Department of Chemical & Biological Engineering Outstanding Junior Faculty Award, 2016
  • NSF CAREER Award, 2015
  • University of Colorado College of Engineering Dean’s Faculty Fellowship, 2013
  • U.S. Army Research Office Young Investigator Award, 2012
  • UK Medical Research Council Career Development Fellowship, 2008

Grover N, Plaks JG, Summers SR, Chado GR, Schurr MJ, Kaar JL. Acylase-containing polyurethane coatings with anti-biofilm activity. Biotechnol Bioeng 2016; 113(12):2535-2543.

Chado GR, Stoykovich MP, Kaar JL. Role of dimension and spatial arrangement on the activity of biocatalytic cascade reactions on scaffolds. ACS Catal 2016; 6:5161-5169.

Faulón Marruecos D, Kastantin M, Schwartz DK, Kaar JL. Dense poly(ethylene glycol) brushes reduce adsorption and stabilize the unfolded conformation of fibronectin. Biomacromolecules 2016; 17(3):1017-1025.

Weltz JS, Schwartz DK, Kaar JL. Surface-mediated protein unfolding as a search process for denaturing sites. ACS Nano 2016; 10(1):730-738.

Nordwald EM, Plaks JG, Snell JR, Sousa MC, Kaar JL. Crystallographic investigation of imidazolium ionic liquid effects on enzyme structure. ChemBioChem 2015; 16(17):2456-2459.

MacConaghy KI, Chadly DM, Stoykovich MP, Kaar JL. Label-free dection of missense mutations and methylation differences in the p53 gene using optically diffracting hydrogels. Analyst 2015; 140(18):6354-6362.

Plaks JG, Falatach R, Kastantin M, Berberich JA, Kaar JL. Multi-site clickable modification of proteins using lipoic acid ligase. Bioconjug Chem 2015; 26(6):1104-1112.

MacConaghy KI, Chadly DM, Stoykovich MP*, Kaar JL. Optically diffracting hydrogels for screening kinase activity: impact of material and solution properties. Anal Chem 2015; 87(6):3467-3475.

Nordwald EM, Armstrong GS, Kaar JL. NMR-guided rational engineering of an ionic liquid tolerant lipase. ACS Catal 2014; 4(11):4057-4064.

MacConaghy KI, Geary CI, Kaar JL, Stoykovich MP. Photonic crystal kinase biosensor. J Am Chem Soc 2014; 136(19):6896-6899.

Nordwald EM, Brunecky R, Himmel ME, Beckham GT, Kaar JL. Charge engineering of cellulases improves ionic liquid tolerance and reduces lignin inhibition. Biotechnol Bioeng 2014; 111(8):1541-1549.

McLoughlin SY, Kastantin M, Schwartz DK, Kaar JL. Single Molecule resolution of protein structure and interfacial dynamics on biomaterial surfaces. Proc Natl Acad Sci U S A 2013; 110(48):19396-19401.

Nordwald EM, Kaar JL. Stabilization of enzymes in ionic liquids via modification of enzyme charge. Biotechnol Bioeng 2013; 110(9):2352-2360.