Craig A Aspinwall

Craig A Aspinwall

Department Head, Chemistry & Biochemistry - Sci
Professor, Chemistry and Biochemistry-Sci
Professor, Chemistry and Biochemistry - Med
Professor, Biomedical Engineering
Professor, BIO5 Institute
Member of the General Faculty
Member of the Graduate Faculty
Primary Department
Department Affiliations
Contact
(520) 621-6338

Research Interest

Craig A. Aspinwall, PhD, is an Associate Professor of Chemistry and Biochemistry at the University of Arizona. Dr. Aspinwall’s research is focused on the development of novel technology that facilitates the investigation of the molecular underpinnings of disease states. His work encompasses a broad range of scientific disciplines and allows complex biochemical problems to be studied with an increasing level of molecular detail. Dr. Aspinwall has published over 40 original research papers and maintains active collaborations with several international investigators. His research has been funded by the National Institutes of Health, the National Science Foundation, the Arizona Biomedical Research Corporation, and other organizations. He is actively involved in mentoring and education of students and young scientists.

Publications

Cheng, Z., Zaki, A. A., Jones, I. W., Hall, H. K., Aspinwall, C. A., & Tsourkas, A. (2014). Stabilized porous liposomes with encapsulated Gd-labeled dextran as a highly efficient MRI contrast agent. Chemical Communications, 50(19), 2502-2504.

Abstract:

A highly efficient contrast agent for magnetic resonance imaging was developed by encapsulating gadolinium within a stabilized porous liposome. The highly porous membrane leads to a high relaxivity of the encapsulated Gd. The stability of the liposome was improved by forming a polymer network within the bilayer membrane. © 2014 The Royal Society of Chemistry.

Li, Z., Muhandiramlage, T. P., Keogh, J. P., Hall, H. K., & Aspinwall, C. A. (2015). Aptamer-functionalized porous phospholipid nanoshells for direct measurement of Hg(2+) in urine. Analytical and bioanalytical chemistry, 407(3), 953-60.

A porous phospholipid nanoshell (PPN) sensor functionalized with a specific aptamer sensor agent was prepared for rapid detection of Hg(2+) in human urine with minimal sample preparation. Aptamer sensors provide an important class of optical transducers that can be readily and reproducibly synthesized. A key limitation of aptamer sensors, and many other optical sensors, is the potential of biofouling or biodegradation when used in complex biological matrices such as serum or urine, particularly when high levels of nucleases are present. We prepared Hg(2+)-responsive, PPN-encapsulated aptamer sensors that overcome these limitations. PPNs provide a protective barrier to encapsulate the aptamer sensor in an aqueous environment free of diffusional restrictions encountered with many polymer nanomaterials. The unique porous properties of the PPN membrane enable ready and rapid transfer of small molecular weight ions and molecules into the sensor interior while minimizing the macromolecular interactions between the transducer and degradants or interferents in the exterior milieu. Using Hg(2+)-responsive, PPN-encapsulated aptamer sensors, we were able to detect sub-100 ppb (chronic threshold limit from urine test) Hg(2+) in human urine with no sample preparation, whereas free aptamer sensors yielded inaccurate results due to interferences from the matrix. The PPN architecture provides a new platform for construction of aptamer-functionalized sensors that target low molecular weight species in complex matrices, beyond the Hg(2+) demonstrated here.

Aspinwall, C. A., Brooks, S. A., Kennedy, R. T., & R., J. (1997). Effects of intravesicular H+ and extracellular H+ and Zn2+ on insulin secretion in pancreatic beta cells. Journal of Biological Chemistry, 272(50), 31308-31314.

PMID: 9395458;Abstract:

The effects of extracellular Zn2+ and pH and intravesicular pH on insulin and 5-hydroxytryptamine (5-HT) secretion from pancreatic beta cells were investigated. Insulin and 5-HT secretion from single cells was detected by amperometry as a series of current spikes corresponding to detection of multimolecular packets secreted by exocytosis. Spike width was used as a measure of the kinetics of clearance from the cell and the area of spikes as a measure of amount released. Changes in extracellular pH from 6.9 to 7.9 caused insulin spikes to become narrower with no change in area, whereas the same treatments had no effect on 5-HT secretion. Treatment of cells with Bafilomycin A1 or N-ethylmaleimide, both of which are expected to increase intravesicular pH by inhibiting V-type H+-ATPase, had no effect on 5-HT secretion but caused insulin spikes to become more narrow. These results indicate that exposure to high pH, whether intravesicular or extracellular, accelerates release of insulin during exocytosis without affecting the amount of insulin released. Increasing extracellular Zn2+ concentration from 0 to 25 μM increased the width and decreased the area of insulin spikes without affecting 5-HT secretion. Zn2+ effects were likely exerted through a common-ion effect on Zn2+-insulin dissociation. It was concluded that intravesicular storage conditions and extracellular ions can affect free insulin concentration in the vicinity of beta cells during secretion.

Agasid, M. T., Comi, T. J., Saavedra, S. S., & Aspinwall, C. A. (2017). Enhanced Temporal Resolution with Ion Channel-Functionalized Sensors Using a Conductance-Based Measurement Protocol. ANALYTICAL CHEMISTRY, 89(2), 1315-1322.
Aspinwall, C., Mansfield, E., Ross, E. E., & Aspinwall, C. A. (2007). Preparation and characterization of cross-linked phospholipid bilayer capillary coatings for protein separations. Analytical chemistry, 79(8).

Analysis of protein and peptide mixtures via capillary electrophoresis is hindered by nonspecific adsorption of analytes to the capillary walls, resulting in poor separations and quantitative reproducibility. Phospholipid bilayer (PLB) coatings are very promising for improving protein and peptide separations due to the native resistance to nonspecific protein adsorption offered by PLBs; however, these coatings display limited chemical and temporal stability. Here, we show the preparation and characterization of a highly cross-linked, polymerized phospholipid capillary coating prepared using bis-SorbPC. Poly(bis-SorbPC) PLB coatings are prepared in situ within fully enclosed fused silica capillaries via self-assembly and radical polymerization. Polymerization of the PLB coating stabilizes the membrane against desorption from the surface and migration in an electric field, improves the temporal and chemical stability, and allows for the separation of both cationic and anionic proteins, while preserving the native resistance to nonspecific protein adsorption of natural PLBs.