Dispersible Conjugated Polymer Nanoparticles as Biointerface Materials for Label-Free Bacteria Detection

Abstract

Fast and efficient identification of bacterial pathogens in water and biological fluids is an important issue in medicine, food safety and public health concerns that requires low-cost and improved sensing strategies. Impedimetric sensors are promising tools for monitoring bacteria detection, due to their reliability and ease-of-use. We herein report a study on a new bio-interface-based amphiphilic poly(3-hexylthiophene)-bpoly(3-triethylene-glycol-thiophene), P3HT-b-P3TEGT, for label-free impedimetric detection of Escherichia coli (E. coli). This bio-interface is fabricated by selfassembly of P3HT-b-P3TEGT into core-shell nanoparticles, which are further decorated with mannose, leading to an easy-to-use solution-processable nanoparticle material for biosensing. The hydrophilic block, P3TEGT promotes antifouling and prevents non-specific interactions while improving the ionic and electronic transport properties, thus enhancing the electrochemical-sensing capability in aqueous solution. Self-assembly and micelle formation of P3HT-b-P3TEGT were analyzed by 2D-NMR, FTIR, DLS, contact angle and microscopy characterizations. Detection of E. coli was characterized and evaluated by electrochemical impedance spectroscopy, optical and scanning electron microscopy techniques. The sensing layer based on mannose-functionalized P3HT-b-P3TEGT nanoparticles demonstrates targetingability toward E. coli pili protein with a detection range from 10 3 CFU/mL to 10 7 CFU/mL and selectivity studied with Gram(+)bacteria. Application to real samples was performed by detection of bacteria in tap water and Nile water. The approach developed here shows that water/alcohol-processable functionalized conjugated polymer nanoparticles are suitable for use as electrode materials for the fabrication of a low-cost label-free impedimetric biosensor for the detection of bacteria in water.

3,4-Ethylenedioxythiophene (EDOT) End-Group Functionalized Poly-ε-caprolactone (PCL): Self-Assembly in Organic Solvents and Its Coincidentally Observed Peculiar Behavior in Thin Film and Protonated Media

“…Based on the through-space dipole–dipole interaction, NOESY experiments have provided significant information on both the intra- and inter-molecular proximity of protons [ 64 ] that have sufficient rotational mobility [ 65 ] and which had internuclear distances that were typically <0.5 nm. This provided excellent insights into the nature of the micelle-forming process [ 65 , 66 , 67 ], which is applicable in any kind of self-assembled structure, for any geometry, and for any type of constituents [ 65 ].…”

Current Progress of Interfacing Organic Semiconducting Materials with Bacteria

“…Positively charged p-doped polymers can electrostatically bind with the negatively charged outer membrane of bacteria and thereby enhance direct electron transfer between the electrode and microbes. Specific types of recognition elements have also been utilized to obtain selectivity toward certain microbes. − These hybrid materials can also accelerate biofilm formation, a relevant requirement for MESs. ,,− The ability to copolymerize or functionalize polymers with biomolecular recognition units, such as aptamers, gives rise to specificity. ,− Aptamers consist of short oligonucleotides or peptides generated by a combinatorial method, usually called ligands’ systematic evolution by exponential enrichment (SELEX). , …”

Principles and Recent Advances in Biosensors for Pathogens Detection

“…On the other hand, conductometric biosensors have a significant drawback due to the presence of high background conductivity while examining contaminated water samples, resulting in poor selectivity. [59] This is perhaps one of the reasons for the rare use of biosensors in the detection of foodborne and waterborne pathogens. For instance, Muhammad-Tahir et al [159] developed a conductometric biosensor for the detection of Escherichia coli O157:H7 by developing an electrochemical sandwich immunoassay containing a lateral flow system to allow contaminated water and complex food samples to pass through the sensor assembly (see Figure 4(a) and (b)).…”