Biosensors

Scheme: Illustration of proposed mechanism of real time monitoring of hydrolysis reaction by conjugated polymers
Scheme: Illustration of proposed mechanism of real time monitoring of hydrolysis reaction by conjugated polymers

Prototyping high performance chemo-bio sensing platforms continues to be active focus of chemistry, biology and medicinal science due to growing demand for quick, efficient and affordable diagnosis tools, assays and methodologies. The objective of my research is to design and synthesize of water soluble conjugated polyelectrolytes (CPEs) which are utilized as luminescent biosensors. The high detection capabilities of CPEs make them one of the indispensable components of ultrasensitive biosensors. In this work, I aimed to exploit the potential of the Poly (3-alkylthiophenes) type novel CPEs as an adenosine triphosphate (ATP) sensor for real time activity determination of enzymes regulating protein degradation processes. Due to proposed methodology rapid, practical, and “mix and measure” type assay procedure have been developed for determination of real time kinetics of proteins. This work demonstrated the high potential of CPEs as a sensing material.

Scheme: Illustration of working principle of nano-sized fluorescent ATP sensor made of polymer vesicles
Scheme: Illustration of working principle of nano-sized fluorescent ATP sensor made of polymer vesicles

As follow up work, I have used novel block copolymer to synthesize supramolecular polymersomes for monitoring of enzymatic activity inside porous nanoreactor which co-encapsulate alkaline phosphatase and fluorescent reporter polymers. This allowed to study in detail the diffusion and consumption of the prototypical natural substrate ATP in the containers’ confinement. The possibility to focus on product formation as well as consumption affords a more complete picture of enzyme behaviour at the cellular and organelle level. This part of my study opens a new possibility for sustainable research in the investigation of “purinergic signalling pathways”. As a future perspective, I plan to extend my research to develop functional polymers as well as methodologies to monitor ATP mediated signalling processes in vivo conditions.

Apart from the sensing applications I foresee that CPEs have great potential to improve the performance of cutting edge technology point-of-care devices. I anticipate there are multiple advantages which CPEs can bring in to the field such as i)“green fabrication processes” since active materials are water soluble, ii) nanoscopic control of device morphology by layer by layer assembly.

Related Publications;

1- Real-Time Activity Determination of ATPase by Water Soluble Polythiophenes

Umit Hakan Yildiz, Chia Wei Sheng, Diyar Mailepessov, Diana Chia Xueqi, Susana Geifman Shochat, Bo Liedberg 2012, Analytical & Bioanalytical Chemistry,

404, 8, 2369-2375.

2- Third-Party ATP Sensing in Polymersomes: a label-free assay of enzyme reactions in vesicular compartments

Umit Hakan Yildiz, Hans-Peter M. De Hoog, Zhikang Fu, Nikodem Tomczak, Atul Parikh, Madhavan Nallani, Bo Liedberg (Accepted, Small)

3- A Sensitive Polythiophene based Cationic Sensor for Nucleoside Triphosphates

Umit Hakan Yildiz, Reinhard Haselsberger, Ma Lin, Gagik Gurdzadyan, Bo Liedberg and Michel-Beyerle M. E. (in preparation)