Dr. Virginia M. Ayres
The Electronic and Biological Nanostructures Laboratory
Research - Scanning Probe Recognition Microscopy/Nanobiology
SCANNING PROBE RECOGNITION MICROSCOPY
Scanning Probe Recognition Microscopy (SPRM) is a new scanning probe microscopy capability developed with myself as Principal Investigator in an NSF GOALI collaborative partnership with Veeco Instruments. In Scanning Probe Recognition Microscopy, the scanning probe microscope system itself is given the power auto-track specific regions of interest through feature recognition coupled with adaptive scan plan generation and implementation. 'Feature' means any recognizable element, not just topography; for example, I currently investigate nanoscale elasticity as a physical property feature. SPRM is an approach that works directly with the interaction sensing capability of a scanning probe microscope, which inherently has atomic to nanometer scale resolution. The human operator interaction is now focused to the decision-making level rather than the execution level, and the research emphasis evolves from sample imaging to feature/property investigation.
Scanning Probe Recognition Microscopy in Regenerative Medicine
In the images shown below, SPRM is used to auto-track along individual nanofibers within a nanofibrillar matrix of electrospun polyamide nanofibers, enabling property extraction including nanoscale elasticity and surface roughness. Data from SPRM auto-track investigations over multiple individual nanofibers is compiled into a new, statistical representation of each property for the nanofibrillar matrix as a whole. These particular nanofibrillar matrices are used as tissue scaffolds for regenerative medicine for the central nervous system (brain and spinal cord), which is one of the most challenging injury repair situations.
Figure 3. SPRM statistical plot of nanofibrillar matrix elasticity. Neural cell interactions are directed by both biochemical cues and physcial cues, including nanoscale elasticity. SPRM invesitgation shows that the overall nanofibrillar matrix elasticity changes when the nanofibers are covalently modified with growth factor FGF-2, to mimic sequestration of growth factors on the extracellular matrix at the blood-brain barrier. (Ayres, V, et al, Int. J. Nanomanufacturing, in press, 2009)
Figure 4. Unmodified versus covalently FGF-2 modified nanofibers. Survey AFM images of nanofibrillar scaffolds showing unmodified and covalently FGF-2 modified nanofibers. (AFM images: Ayres' EBNL group, MSU) (Delgado-Rivera, R, et al, Matrix Biology, 2009)
Figure 5. Astrocytes on 2D versus 3D nanofibrillar substrates. Collaborative work with Dr. Sally Meiners at the University of Medicine and Dentistry of New Jersey (UMDNJ) is linking the nanoscale physical and biochemical cues of the prosthetic nanofibrillar scaffolds with important astrocyte and astrocyte-neuron responses. Significant differences in astrocyte response to 2D planar, 3D nanofibrillar and 3D nanofibrillar covalently modified with FGF-2 substrates are observed. The most in-vivo-like response is to 3D nanofibrillar covalently modified with FGF-2 substrates but even unmodified 3D nanofibrillar substrates improve life for astrocytes. (Optical images: Meiners' group, UMDNJ) (Delgado-Rivera, R, et al, Matrix Biology, 2009)