Programmable cell-free transcriptional switches for antibody detection

We report here the development of a cell-free in-vitro transcription system for the detection of specific target antibodies. The approach is based on the use of programmable antigen-conjugated DNA-based conformational switches that, upon binding to a target antibody, can trigger the cell-free transcription of a light-up fluorescence-activating RNA aptamer. The system couples the unique programmability and responsiveness of DNA-based systems with the specificity and sensitivity offered by invitro genetic circuitries and commercially available transcription kits. We demonstrate that cell-free transcriptional switches can efficiently measure antibody levels directly in blood serum. Thanks to the programmable nature of the sensing platform the method can be adapted to different antibodies: we demonstrate here the sensitive, rapid and cost-effective detection of three different antibodies and the possible use of this approach for the simultaneous detection of two antibodies in the same solution

Percolation breakdown in binary and ternary monodisperse and polydisperse systems of spherical particles

We perform computer simulations of an agglomeration process for monodisperse and polydisperse systems of spherical particles in a cylindrical container, using a simplified stochastic-hydrodynamic model. We consider a ternary system with three particle types A, B, and C, in which only connections of the type can be forged, while any other connections with particles of the same type or with C-particles are forbidden, and for comparison a binary system with two particle types A and C, in which only connections of the type can be formed. We study the breakdown of the percolation in the agglomeration at the bottom of the cylinder with an increasing fraction of C-particles

Kauffman Model with spatially separated ligation and cleavage reactions

One of the open questions regarding the origin of life is the problem how macromolecules could be created. One possible answer is the existence of autocatalytic sets in which some macromolecules mutually catalyze each other’s formation. This mechanism is theoretically described in the Kauffman model. We introduce and simulate an extension of the Kauffman model, in which ligation and cleavage reactions are spatially separated in different containers connected by diffusion, and provide computational results for instances with and without autocatalytic sets, focusing on the time evolution of the densities of the various molecules. Furthermore, we study the rich behavior of a randomly generated instance containing an autocatalytic metabolism, in which molecules are created by ligation processes and destroyed by cleavage processes and vice versa or generated and destroyed both by ligation processes