Pathogen detection based on nano-engineered polydopamine biosensors

Abstract

facile method which can be adjusted on various surfaces, able to functionalize in different ways, and shows great biocompatibility. With solid advantages, polydopamine have implied with several approaches in biotechnology. Herein, we present two different diagnosis methods for the rapid diagnosis of pathogen, using polydopamine biosensors. This thesis is organized as follows.In chapter 1 first describes the importance of pathogen detection and development of rapid diagnosis methods. Also, the characteristic and applications of polydopamine is briefly introduced. Chapter 2 describes the fluorescent detection of live bacteria coupled with polydopamine formation. During exponential growth of bacteria oxygen depletion is caused by large consumption of oxygen by bacteria, which inhibits the polymerization of dopamine. In contrast, polymerization of dopamine occurs during the steady-state growth of bacteria because high-oxygen concentration in solution, which is not consumed by bacteria. This difference in polydopamine formation is also described by the fluorescent dextran nanoparticles (FDNPs) as sensors. Fluorescence of FDNP is controlled by the polydopamine formations, which is strongly related with bacterial growth. Coupling of bacterial growth – polydopamine formation – and fluorescence of FDNPs were also used for the detection of antibacterial resistant bacteria (NDM1+ E. coli). In chapter 3, Type II clustered regularly interspaced short palindromic repeats (CRISPR) associated protein (Cas) system was used to detect genomic targets. We immobilized the RNA guidable nuclease-deficient Cas9 (dCas9) proteins on polydopamine particle (PDNP) for the rapid detection of nucleic acids. When the target genes are present in sample solution, dCas9 holds the genes onto PDNP surface, and PDNP quenches the fluorescent dye bound to the target. In this thesis we developed different methods for the diagnosis of pathogens using different characteristics of polydopamine. With these studies, I was able to obtain a broad and in-depth understanding of polydopamine chemistry, and ability to apply polydopamine in different ways for the biotechnological applications.

With growing deaths from late diagnosis of diseases, development of rapid and simple diagnosis method is essential for the early treatment of disease. We used polydopamine based chemistry for the development of biosensors to detect the pathogen. Polydopamine have several benefits at surface functionalization