Fluorescent polymer as a biosensing tool for the diagnosis of microbial pathogens.

Diseases and diagnoses are predominant in the human population. Early diagnosis of etiological agents plays a vital role in the treatment of bacterial infections. Existing standard diagnostic platforms are laborious, time-consuming, and require trained personnel and cost-effective procedure, though they are producing promising results. These shortcomings have led to a thirst for rapid diagnostic procedures. Fluorescence-based diagnosis is one of the efficient rapid diagnostic methods that rely on specific and sensitive bacterial detection. Emerging bio-sensing studies on conducting polymers (CPs) are gaining popularity in medical diagnostics due to their promising properties of high fluorescence efficiency, good light stability, and low cytotoxicity. Poly[2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV), is the first identified soluble polymer and model material for understanding the fundamental photophysics of conventional CPs. In this present study, MEH-PPV is used as a fluorescent dye for direct pathogen detection applications by interacting with the microbial cell surface. An optimized concentration of MEH-PPV solution used to confirm the presence of selective bacterial structures. The present study endeavours towards bacterial detection based on the emission from bacteria due to interfacial interaction between polymer and bacterial surface.

Role of defective states in MgO nanoparticles on the photophysical properties and photostability of MEH-PPV/MgO nanocomposite.

Hybrid organic-inorganic nanocomposites employ metal oxides to improve the charge transport properties and stability of the conjugated polymer. They are considered one of the most interesting candidates for optoelectronic applications. This article presents a detailed investigation on the influence of defective electronic states of MgO nanoparticles on the photophysical properties and photostability of a conjugated polymer, poly[2-methoxy-5-(2-ethylhyxyloxy)-1,4-phenylene vinylene] (MEH-PPV). Since MgO is an insulator (Eg - 7.8 eV), defect states were induced to improve the delocalization of electrons and conductivity. These defect-induced MgO nanoparticles accounted for the enhanced absorbance in the hybrid polymer nanocomposites. The nanocomposites demonstrated photoluminescence (PL) quenching owing to the transfer of electrons from MEH-PPV to the defective energy levels (oxygen vacancies) of MgO. The photoinduced electron transfer was confirmed through solvent and temperature-dependent PL analysis, and also through electrochemical analysis. The MEH-PPV/MgO nanocomposite displayed 23% PL quantum efficiency. An improvement in photostability was observed due to the reduction in the polymer chain defects, prevention of oxygen diffusion by MgO nanoparticles, inhibition of moisture intervention by improving the hydrophobicity of nanocomposites, and most importantly, transfer of electrons from the polymer to oxygen vacancies, which prohibited superoxide formation. Hence, this work validates the role of oxygen vacancies of MgO nanoparticles in the PL quenching and photostability enhancement of MEH-PPV.

Correction: Role of defective states in MgO nanoparticles on the photophysical properties and photostability of MEH-PPV/MgO nanocomposite.

Correction for 'Role of defective states in MgO nanoparticles on the photophysical properties and photostability of MEH-PPV/MgO nanocomposite' by Sangeetha Ashok Kumar et al., Phys. Chem. Chem. Phys., 2021, 23, 22804-22816, DOI: 10.1039/d1cp03035c.