Synthetic analog computation in living cells.

A central goal of synthetic biology is to achieve multi-signal integration and processing in living cells for diagnostic, therapeutic and biotechnology applications. Digital logic has been used to build small-scale circuits, but other frameworks may be needed for efficient computation in the resource-limited environments of cells. Here we demonstrate that synthetic analog gene circuits can be engineered to execute sophisticated computational functions in living cells using just three transcription factors.

Stochastic signaling in biochemical cascades and genetic systems in genetically engineered living cells.

Living cells, either prokaryote or eukaryote, can be integrated within whole-cell biochips (WCBCs) for various applications. We investigate WCBCs where information is extracted from the cells via a cascade of biochemical reactions that involve gene expression. The overall biological signal is weak due to small sample volume, low intrinsic cell response, and extrinsic signal loss mechanisms.

Dielectric screening of early differentiation patterns in mesenchymal stem cells induced by steroid hormones.

In the framework of this study, target identification and localization of differentiation patterns by means of dielectric spectroscopy is presented. Here, a primary pre-osteoblastic bone marrow-derived MBA-15 cellular system was used to study the variations in the dielectric properties of mesenchymal stem cells while exposed to differentiation regulators. Using the fundamentals of mixed dielectric theories combined with finite numerical tools, the permittivity spectra of MBA-15 cell suspensions have been uniquely analyzed after being activated by steroid hormones to express osteogenic phenotypes.

Development of a quantitative optical biochip based on a double integrating sphere system that determines absolute photon number in bioluminescent solution: application to quantum yield scale realization.

We report a new design of an optical biochip based on a double integrating sphere system to quantify the absolute number of the emitted photons or the total photon flux by a whole cell bioluminescent biosensor, for water toxicity detection, based on genetically engineered Escherichia coli bacteria carrying a recA::luxCDABE promoter-reporter fusion. The new design of the double integrating sphere system does not require any external standard light source for calibration of the tested bioluminescent solution and allows a direct determination of the total photon flux of the bioluminescent solution. In our design, we required that the two spheres are symmetric (have the same radius and reflectance) with a surface area larger than the cut cap area between the spheres.

Modeling and measurement of a whole-cell bioluminescent biosensor based on a single photon avalanche diode.

Whole-cell biosensors are potential candidates for on-line and in situ environmental monitoring. In this work we present a new design of a whole-cell bioluminescence biosensor for water toxicity detection, based on genetically engineered Escherichia coli bacteria, carrying a recA::luxCDABE promoter-reporter fusion. Sensitive optical detection is achieved using a single photon avalanche photodiode (SPAD) working in the Geiger mode.