Marine mussels secrete proteins rich in residues containing catechols and cationic amines that displace hydration layers and adhere to charged surfaces under water via a cooperative binding effect known as catechol-cation synergy. Mussel-inspired adhesives containing paired catechol and cationic functionalities are a promising class of materials for biomedical applications, but few studies address the molecular adhesion mechanism(s) of these materials. To determine whether intramolecular adjacency of these functionalities is necessary for robust adhesion, a suite of siderophore analog surface primers was synthesized with systematic variations in intramolecular spacing between catechol and cationic functionalities. Adhesion measurements conducted with a surface forces apparatus (SFA) allow adhesive failure to be distinguished from cohesive failure and show that the failure mode depends critically on the siderophore analog adsorption density. The adhesion of these molecules to muscovite mica in an aqueous electrolyte solution demonstrates that direct intramolecular adjacency of catechol and cationic functionalities is not necessary for synergistic binding. However, we show that increasing the catechol-cation spacing by incorporating nonbinding domains results in decreased adhesion, which we attribute to a decrease in the density of catechol functionalities. A mechanism for catechol-cation synergy is proposed based on electrostatically driven adsorption and subsequent binding of catechol functionalities. This work should guide the design of new adhesives for binding to charged surfaces in saline environments.

A course is described where students are engaged in an inquiry-based quarter-long research project to synthesize a known pharmaceutical target. Students use literature search engines, such as Reaxys and SciFinder, and the primary chemical literature as resources to plan and perform the synthesis of their pharmaceutical target. Through this process, students develop critical thinking, problem solving, and data analysis skills in the laboratory setting. Teaching assistants guide students through three phases of the research process: (1) literature-based proposal, (2) experimentation and analysis, and (3) communication of research findings by oral presentation and written report. This course is designed for upper-division chemistry majors, taken as the third-quarter organic laboratory class after two quarters of introductory laboratory courses and two quarters of the associated organic chemistry lecture courses. Nine different teaching assistants have taught the course described to over 90 students in four different quarters.

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