Colorimetric and Fluorometric Assays Based on Conjugated Polydiacetylene Supramolecules for Screening Acetylcholinesterase and Its Inhibitors

Polydiacetylene supramolecules (PDAs) are unique sensing materials. Upon environmental stimulation, blue PDAs can undergo a colorimetric transition from blue to red accompanied by fluorescence enhancement. In this paper, we report a new PDA system polymerized from a mixed liposome comprising 2-(2-(2-hydroxyethoxy)­ethoxy)­ethyl pentacosa-10,12-diynoate and pentacosa-10,12-diynoic acid at a 3:7 ratio. The PDA system provided new colorimetric and fluorometric assay methods for screening acetylcholinesterase and its inhibitors through three processes. First, myristoylcholine reacted with PDAs, which then underwent colorimetric and fluorometric transition. Second, acetylcholinesterase catalyzed the hydrolysis of myristoylcholine into tetradecanoic acid, which reduced the myristoylcholine concentration and led to faded color and fluorescence. Third and last, acetylcholinesterase inhibitors retarded the activity of acetylcholinesterase, thereby inducing the recovery of color and fluorescence

Additional file 2 of Recombinant-attenuated Salmonella enterica serovar Choleraesuis vector expressing the PlpE protein of Pasteurella multocida protects mice from lethal challenge

Supplementary Material

Additional file 1 of Recombinant-attenuated Salmonella enterica serovar Choleraesuis vector expressing the PlpE protein of Pasteurella multocida protects mice from lethal challenge

Supplementary Material

Liquid–Solid Dual-Gate Organic Transistors with Tunable Threshold Voltage for Cell Sensing

Liquid electrolyte-gated organic field effect transistors and organic electrochemical transistors have recently emerged as powerful technology platforms for sensing and simulation of living cells and organisms. For such applications, the transistors are operated at a gate voltage around or below 0.3 V because prolonged application of a higher voltage bias can lead to membrane rupturing and cell death. This constraint often prevents the operation of the transistors at their maximum transconductance or most sensitive regime. Here, we exploit a solid–liquid dual-gate organic transistor structure, where the threshold voltage of the liquid-gated conduction channel is controlled by an additional gate that is separated from the channel by a metal-oxide gate dielectric. With this design, the threshold voltage of the “sensing channel” can be linearly tuned in a voltage window exceeding 0.4 V. We have demonstrated that the dual-gate structure enables a much better sensor response to the detachment of human mesenchymal stem cells. In general, the capability of tuning the optimal sensing bias will not only improve the device performance but also broaden the material selection for cell-based organic bioelectronics