ABSTRACT
I. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 887
II. Design of Micro-Biosensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 888
III. Immobilization of Chromatophores . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 889
IV. Experimental . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 890
A. Isolation of Primary Cell Culture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 890
B. Microcarriers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 890
C. Cell Immobilization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 891
D. Analysis of Attachment Kinetics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 891
E. Capturing of Microcapsules Using Magnetic Field . . . . . . . . . . . . . . . . . . . 891
F. Testing of Immobilized Chromatophores with Clonidine . . . . . . . . . . . . . . . 892
V. Results and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 892
A. Attachment of Cells to Microcarriers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 892
1. Kinetics of Attachment to Gelatin Beads . . . . . . . . . . . . . . . . . . . . . . . 893
2. Effect of Cell-to-Bead Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 894
B. Capturing of Microcapsules Using Magnetic Field . . . . . . . . . . . . . . . . . . . 895
C. Testing of Immobilized Chromatophores Using Clonidine . . . . . . . . . . . . . 896
1. Fitting Experimental Data with a Double Exponential
Model for Cell Area Decrease . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 896
2. Effect of Toxin Concentration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 899
VI. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 899
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 900
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 900
Chromatophores are terminally differentiated, neuron-like cells containing pigmented granules that are
responsible for the brilliant colors of fish, amphibians, reptiles, and cephalopods, and their dynamic
color adaptations and adjustable camouflage capabilities [1,2]. Chromatophores are located in the
skin and scale tissues of fish. They are biochemically related to nerve cells and share many of their
important sensory properties and responses to biologically active chemical agents. Various biologi-
cally active and toxic substances can act on chromatophores as signaling molecules through the recep-
tors placed on the cell surface. Chromatophore responses to these agents are mediated through a
complex array of cell surface receptors, signal transduction pathways, and metabolic processes result-
ing in the movement of pigment granules along microtubules [3,4]. Figure 32.1 presents a
characteristic response of chromatophores to biologically active agents. Changes in pigment color and
location within cells can be monitored microscopically. In addition to various environmental toxins
such as heavy metals, organophosphate pesticides, polynuclear aromatic hydrocarbons [5], herbicides,
fungicides, and some genotoxins [6], the cytosensor has the capability to detect a wide variety of
potential toxicants from various classes of bacterial toxins to numerous cell-receptor agonists [7].
