Jonathan Ashby

Mount Holyoke Fellow; Visiting Lecturer in Chemistry
Specialization: 
bioanalytical chemistry, separation sciences

Jonathan Ashby received his doctorate from the University of California, Riverside, where he used open-channel separation methods for the isolation of biomolecular complexes, such as proteins bound to nanoparticles and nucleic acid carriers in human serum. His postdoctoral studies at the University of California, Davis focused on affinity purification of DNA repair enzymes using non-cleavable lesion analogs.  Ashby’s research interests at Mount Holyoke involve the development of lower-cost, higher throughput assays that can act as alternatives to established methodology.

One of Ashby’s research projects involves developing tools for investigating protein-protein binding interfaces. In Ashby’s research group, amino-acid specific tags, such as fluorescamine, are used to tag the surface of a protein. As the protein-protein binding interface is shielded from the solvent environment, it cannot be tagged. Through comparison of the tagging locations on the single proteins and the protein-protein complex via mass spectrometry, identification of the binding interface is possible.

Another of Ashby’s research projects involves designing DNA aptasensors for small molecules. Aptamers are an attractive alternative to antibodies due to their ease of production, their ability to bind to targets under a wide variety of enviromental conditions, and their ability to be developed for targets that antibodies cannot be developed for. High affinity aptamers can be selected from a large, randomized DNA library for a target through a process known as SELEX (Selective Evolution of Ligands via EXponential enrichment). The Ashby lab is looking at aptamer selection for neurodegenerative disease biomarkers. The selection process focuses on finding high affinity aptamers, where the aptamer undergoes significant structural change upon binding to the target. These aptamers can then be used in a variety of sensing platforms for point-of-care analysis or high-throughput screening.

Ashby teaches introductory chemistry and analytical chemistry. In his analytical chemistry course, one of the focuses is on science communication, such as learning how to give an elevator pitch, as well as learning how to effectively write short technical notes. In addition, another focus is on the critical comparison of different methods for chemical analysis.

 

Selected Presentations (* indicates undergraduate researcher, ** - co-first author):

Ashby, Jonathan; Ligans, Erik*; Tamsi, Michael*; Zhong, Wenwan. High-throughput profiling of nanoparticle-protein interactions by fluorescence labeling. Anal. Chem., 2015, 87, 2213-2219.

 Ashby, Jonathan**; Flack, Kenneth**; Jimenez, Luis; Duan, Yaokai; Kareem-Khatib, Abdel*; Somlo, George; Wang, Shizen Emily; Cui, Xinping; Zhong, Wenwan. Distribution profiling of circulating microRNAs in serum. Anal. Chem.201486, 9343–9349.

 Ashby, Jonathan; Pan, Songquin; Zhong, Wenwan. Size and surface functionalization of iron oxide nanoparticles influence the composition and dynamic nature of their protein corona. ACS Appl. Mater. Interfaces20146, 15412–15419.

 Ashby, Jonathan**; Schachermeyer, Samantha**; Duan, Yaokai; Jimenez, Luis; Zhong, Wenwan. Probing and quantifying DNA-protein interactions with asymmetrical flow field-flow fractionation. J. Chrom. A., 2014, 1358, 217-224.