Cristian Staii, Ph.D. - US grants

1067093
Staii

Intellectual merit: The objective of this proposal is to gain a deeper understanding of the basic rules that neuronal cells use to form functional connections with one another. Understanding the brain is of tremendous fundamental importance, but it is immensely challenging because of the complexity of both its architecture and function. The central nervous system consists of many different spatially localized and yet highly interconnected regions. To date the processes involved in forming functional neuronal connections, the mechanisms of axonal navigation to their target region and their specific interactions with guidance factors such as chemical gradients and mechanical cues are still largely unknown. The scientific goal of the current project is to understand the fundamental processes governing the development of connections and communications between neurons in living systems by studying the growth and interconnectivity of small numbers of neurons patterned in simplified, well-controlled geometries. The central hypothesis is that simplifying the neuronal growth environment by creating highly controlled neuronal circuits in vitro will allow the basic rules that underlie neuronal development and the formation of neural connections to be elucidated.

Simple neuronal networks will be created on two dimensional substrates, guiding the formation of synapses and measuring their electrical activity using a) atomic force microscope nanolithography; b) atomic force imaging and atomic force based electrical force microscopy; c) fluorescence spectroscopy. Specifically, one aims to: 1) pattern different types of proteins/growth factors at precise locations on surfaces and use them as growth templates for fluorescently labeled neurons; 2) guide the formation of neuronal synapses by controlling the type and geometry of the underlying protein patterns; 3) systematically investigate the adhesion and growth of neuronal processes using both atomic force and fluorescence spectroscopy measurements; 4) map the electrical activity of the network by combined electrical force microscopy and fluorescence microscopy. The crucial aspect for this last step is the use of a voltage-biased atomic force tip as a movable electrode to both stimulate and record the electrical activity of patterned neurons, both at the synapse level and along the neuronal pathway. Simultaneous fluorescence monitoring will identify the specific signaling molecules released during synapse formation as well as during the propagation of the electrical signal. By performing these experiments one seeks to a) quantify the role that different types of biochemical and geometrical cues play in neuronal growth and development; b) to measure under what conditions synaptic junctions are functional and c) to learn to control the formation of functional synapses in neuronal circuits having well-defined geometries.

Broader Impacts: The proposed research may lead to great insights into diseases that result when the growth of neuronal processes fails, including birth defects, mental disorders, and sensory-motor deficits. Further, options to direct nerve-material interfaces have broad applicability for prosthetic devices to better mimic human functions. A specific goal for broader impact will be to use the research in the grant as a focused teaching tool for the undergraduates. Specifically, the investigators will establish a Research Mentorship Team which will provide undergraduate students with: a) research intensive experience b) multidisciplinary teams and projects (integration between physics, biology and engineering) such that the students gain exposure to broader thinking outside of their own discipline; c) mentorship experience at the undergraduate level, as senior students will serve as the upper class mentors to the second and third year undergraduate students helping to prepare them for their senior year. The postdoctoral researcher and graduate student involved in the grant will be part of the mentorship team. As part of this activity the investigators will also work directly with Tufts Center for Engineering Education Outreach to explore how to modularize the tools and teaching for use in the broader outreach activities.

PI: Sokolov, Igor
Proposal: 1428919
Title: MRI: Acquisition of Raman-AFM-Lifetime System for Materials Research and Training

Significance
The requested system has the ability to collect multiple parameters (using Raman, AFM and optical excitation) from the same area of the sample surface, opening the possibility for a better understanding of surface properties. The system has significant advantages over previous systems, including function-structure studies and uses a smaller amount of laser radiation, thus allowing the study of many organic samples in non-destructive way, and faster acquisition of Raman maps. This new version of confocal imaging Raman spectrometer allows collection of Raman spectra over a sample surface much faster than was previously possible. It opens a window of opportunities for both research and education. In addition to allowing studies of organic samples non-destructively, it will achieve faster acquisition of Raman maps allowing the use of the instrument for real-time demonstrations for students.

Technical Description
The state-of-the-art integrated Raman-AFM-Lifetime system by WITec Instruments Corp. (Alpha 300R+ Raman system) consists of three integrated parts: a Confocal Raman imaging spectrometer, an atomic force microscope (AFM), and a time-correlated single photon counter. It allows measuring a unique synergistic combination of material parameters, which makes this instrument a unique platform for a large number of potential applications and users. The instrument, hosted at the School of Engineering of Tufts University, will be used by researchers from multiple department and schools across Tufts University as well as outside researchers, including those from the Greater Boston Area (in which no similar instrument exists). The instrument gives the material and stress specific information (the Raman part), physical parameters (topography, electrical charges, viscoelastic moduli of the sample; the AFM part), and lifetime of optical excitation (the lifetime part). All these parameters are measured at the same location on the sample surface. Furthermore, the AFM part will substantially enhance the spatial resolution of the Raman mapping by using a combination with AFM through the tip-enhanced Raman spectroscopy (TERS). The option of single-photon sensitivity and ability to measure life-time of radiated light allow, for example, not only luminescent life-time mapping but also the separation of true Raman and (sometimes Raman-look) fluorescent signals, which is important for quantitative measurements.

NON-TECHNICAL SUMMARY

This research involves a new biomaterials strategy to protect living cells. Cells experience many types of environmental stress when they are grown in culture dishes, and can easily be killed when they are injected through a syringe. Cellular stress can also cause changes in cell functions and even trigger diseases. This project utilizes modified silk, a natural and inexpensive protein biomaterial as a barrier to isolate the cells from their surroundings and protect the cells from being stressed and damaged. Ultrathin coatings on cells will be used for cell protection under unfavorable conditions to maintain normal cell functions. The results should provide insight into new biomaterial systems and interfaces for successful cell and tissue engineering. The work will also provide education and research opportunities for a broad range of students including underrepresented minorities, post-graduate entrepreneurship students, and materials science and engineering students at Tufts and beyond via dissemination. The project will provide both virtual learning tools, modules via YouTube videos, and hands-on research opportunities to underrepresented minority students in the Boston area through collaborations with UMass Boston, Roxbury Community College and Bunker Hill Community College. These partnerships will provide a unique opportunity for underrepresented minority students to gain hands-on experience with these systems to study biomaterial designs and cell interactions.

TECHNICAL SUMMARY

The goal of the project is to develop a new family of protein polymers that self-organize in a customizable layer-by-layer fashion, offer versatility in material properties (e.g., mechanics, crosslink type and degree, and provide shape-change features) and can be assembled and utilized with biological systems (e.g., as cell coatings). Nanocoating cells holds promise for protection against harsh environmental and processing conditions by isolating the cells from their surroundings within a physical barrier. The project focuses on a core strategy of building upon tough, selectively designable silk-like protein systems, with the utilization of selective chemistries to match structure-assembly-function biomaterial goals. The plan is to program these designs to modulate mechanics, dynamic shape changes and cell surface assembly, to establish new systems for versatile control of self-assembly that can be programmed for robust mechanical properties in the context of sensitive biological systems such as cells, enzymes and other biological entities. The strategies presented here provide potential benefits for surface engineering of cells, 3D printing, and preservation. Nanocoated cells would find use in clinical and biotechnology applications during in vitro and in vivo manipulation, where cells are exposed to a variety of stresses including proteolytic enzymes, immune attack, or hydrodynamic forces in bioreactors, in the host, or during injection-based delivery or 3D bioprinting. The work will also provide a focus for training underrepresented minority groups in techniques connecting material science and cell/tissue engineering.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.