Professor of Chemical Engineering
DNA/RNA separations, alkylated peptides, capillary electrophoresis, atomic force microscopy
Prof. Schneider's work focuses on the development of novel colloidal and biomolecular materials for bioanalytical devices, pharmaceutical processing, and drug delivery. We are also developing methods to better characterize these biologically inspired materials using atomic force microscopy (AFM) and other aspects of nanotechnology.
Peptide nucleic acids (PNAs) are synthetic materials that hybridize with complementary DNA and RNA with great sequence selectivity. We have developed a series of PNA amphiphiles that self-assemble in solution and bind tightly to nonpolar chromatographic media while retaining their unique DNA binding properties. We have demonstrated that both single-stranded and double-stranded DNA targets can be easily separated from non-target DNA by this tag-and-separate approach. Current efforts include scaling up the process for the large-scale purification of plasmid DNA, and using capillary electrophoresis to separate and concentrate target DNA or RNA in microfluidic, lab-on-a-chip analysis systems.
Many biosensing modalities require that probes be immobilized on surfaces for detection using waveguides, acoustic vibrations, or fluorescence. Here, detection can be slow in highly dilute solutions due to the long (average) distances analytes must traverse to bind immobilized probes. We are working to accelerate the transport of these analytes to surface-bound probes by approaches that encourage surface diffusion or employ responsive polymers. Surface diffusion and binding kinetics are measured using fluorescence recovery after photobleaching (FRAP) and total-internal-reflection fluorescence (TIRF), respectively.
Tapping-mode AFM is a well established method for the imaging of soft surfaces. We have developed a methodology to interpret the attenuation of the AFM tip oscillation as the tip approaches soft surfaces. By accounting for and removing the effect of hydrodynamic forces and other viscous effects, we obtain the interaction force between tip and sample during a tapping mode experiment. By using this method, we can probe polymer chain dynamics and receptor-ligand interactions at very fast time scales. Currently, we are applying this method to investigate receptor-ligand interactions in polymer thin films similar to those used in biosensors.
|1999–present||Associate Professor, Carnegie Mellon University|
|1998–1999||Postdoctoral Fellow, Naval Research Laboratory, Washington DC|
|1998||Ph.D., University of Minnesota|
Beckman Young Investigator Award
|2001||NSF CAREER Award|
|1998–1999||ASEE Postdoctoral Fellowship, Naval Research Laboratory|
"Effect of Electrostatic Interactions on Binding and Retention of DNA Oligomers to PNA Liposomes Assessed by FRET Measurements," B.F. Marques and J.W. Schneider, Coll. Surf. B: Biointerfaces 53:1-8 (2006).
"A Tapping-Mode AFM Study of the Compression of Grafted Poly(ethylene glycol) Chains," I.M. Nnebe and J.W. Schneider, Macromolecules 39:3616-3621 (2006).
"Morphological Characterization of Self-Assembled Peptide Nucleic Acid Amphiphiles," C. Lau, R. Bitton, H. Bianco-Peled, D.G. Schultz, D.J. Cookson, S.T. Grosser, and J.W. Schneider, J. Phys. Chem. B 110:9027-9033 (2006).
"Peptide Nucleic Acid (PNA) Amphiphiles: Synthesis, Self-Assembly, and Duplex Stability," J.P. Vernille, L.C. Kovell, and J.W. Schneider, Bioconj. Chem. 15:1314-1321 (2004).