Home > Nanotechnology Columns > UAlbany College of Nanoscale Science and Engineering > Nanobioscience at CNSE: Integrating the Animate and Inanimate World
As the feature sizes of physical structures that can be fabricated have continued to shrink, a crossover point has been reached which brings them into the realm of cells (and their internal components), tissues and biomolecules. This evolution has allowed the creation of devices, sensors, and diagnostic/treatment modalities which exploit the advanced capabilities of integrated circuit (IC) fabrication methods. The micro/nano-scale IC approach, known as "Lab on a Chip", can be used to take advantage of specific cell responses or to collect and analyze targeted cells for medical purposes.
May 12th, 2011
Nanobioscience at CNSE: Integrating the Animate and Inanimate World
As the feature sizes of physical structures that can be fabricated have continued to shrink, a crossover point has been reached which brings them into the realm of cells (and their internal components), tissues and biomolecules. This evolution has allowed the creation of devices, sensors, and diagnostic/treatment modalities which exploit the advanced capabilities of integrated circuit (IC) fabrication methods. The micro/nano-scale IC approach, known as "Lab on a Chip", can be used to take advantage of specific cell responses or to collect and analyze targeted cells for medical purposes. The combination of fluidics, electronics, logic and even, optics can be used in unique ways to achieve specific objectives. Multiple research projects are underway in the Nanobioscience Constellation which span the range from fundamental stem cell work to RNA/DNA to functionalized nanoparticles to biosensors and even, health effects and nanotoxicology, among others.
Two examples of the marriage of cells to micro/nano-scale chips take advantage of selected cells' response to certain chemical cues with high specificity and sensitivity. In one case, the living cells are being used to respond to targeted toxins or contaminants in their environment while in the second, the cells are "seduced" into follow a chemical gradient to be captured, counted and phenotyped to study their metastatic dynamics.
The first project established the feasibility of using a bullfrog fibroblast cell line (FT cells) expressing G- protein coupled receptors (GPCRs) as the basis for a living cell-based biosensor. Living cells are particularly attractive as a basis for biosensors. Their main advantage as sensing elements comes from their built-in, naturally selective chemical receptors capable of detecting minute quantities of target molecules. To realize cell-based biosensors, several technical requirements must first be satisfied. The cells must be able to thrive on the device and should have relatively uniform and predictable responses to the detected substances. This response must be convertible into an electronically interpretable signal, and ideally, the cells should be tailorable to respond to different stimulants. .A chip-scale microfluidic "lab" was fabricated by integrating gold microelectrode arrays on a silicon dioxide substrate that supports long term, robust growth of the cells at room temperature and under ambient atmospheric conditions.
The activation of an endogenous GPCR to ATP was monitored with an optical method that detects rises in intracellular calcium and with an electrochemical method that monitors the increased secretion of pre-loaded norepinephrine on a Micro-Electro-Mechanical System (MEMS) device. FT cells were also transfected to express reporter genes driven by several different promoters, raising the possibility that they could be modified genetically to express novel GPCRs as well. The ability to harness GPCRs for BioMEMS applications by using cells that are easy to grow on MEMS devices and to modify genetically opens the way for a new generation of devices based on these naturally selective and highly sensitive chemoreceptors. Overall, this project demonstrated the utility of integrating non-mammalian cell lines into BioMEMS devices. Compared to mammalian cells, amphibian cells require fewer nutrients, are more robust at room temperature, and can be kept dormant under refrigeration for prolonged periods of storage, all of which make them attractive for MEMS applications.
The second research project focuses on the design and optimization of a tool to study the in vivo tumor microenvironment. The NANIVID, or NANo IntraVItal Device, is a transparent and biocompatible device that is fabricated using microfabrication techniques. The device consists of two etched glass substrates that are sealed together using a thin polymer membrane to create a reservoir with a single outlet. This reservoir contains a customized hydrogel blend loaded with epidermal growth factor which diffuses out of the hydrogel and attracts metastatic breast cancer cells into the device. Electrodes are patterned inside the reservoir to monitor the collection of cells by an impedance change. The device is used to collect the motile cells from the tumor microenvironment so that analysis of these cells such as gene expression can be performed and compared to the non-motile cell population. The hydrogel system sustains an autonomous, steady release of growth factor into the microenvironment for many hours. MTLn3 and MenaINV are the model cell lines used in our work, both derived from a rat mammary adenocarcinoma.
The NANIVID has been extensively tested and validated in a two dimensional in vitro environment. The long term goal of the project is to perform in vivo studies with the device. Currently, work is being performed to optimize the device for in vivo experiments including design changes and three dimensional in vitro testing in matrigel or collagen matrixes. Preliminary in vivo work in a rat model of mammary cancer is underway.
In addition to a cell collection tool, a second application for the device is as a delivery vehicle of chemicals that manipulate the tumor microenvironment in ways of interest. The hydrogel system can be loaded with various soluble factors which will diffuse out and initiate controlled changes in the microenvironment. An example is cobalt chloride which has been identified as a hypoxia mimicking agent. The NANIVID has been loaded with cobalt chloride and tested in vitro with MTLn3 cells. To verify the delivery of cobalt chloride, immunofluorescence was performed with an antibody to hypoxia inducible factor- 1 alpha (HIF-1a), a transcription factor involved in the cellular response to oxygen deficiency. Confocal microscopy verified that the cells located near the device opening had an increased HIF-1a expression as compared to cells located away from the device. In the future, other induction targets will be investigated including reactive oxygen species, extracellular matrix stiffness, and hypoglycemia.