No abstract

Pathogenic bacteria are a major public cause of foodborne and waterborne infections and are currently among the most serious public health threats. Conventional diagnostic techniques for bacteria, including plate culturing, the polymerase chain reaction, and the enzyme-linked immunosorbent assay, have many limitations, such as time consumption, high rates of false results, and complex instrument requirements. Aptamer-based electrochemical biosensors for bacteria address several of these issues and are promising for bacterial detection. This review discusses the current advances in electrochemical aptasensors for pathogenic bacteria with regard to the sensing performance with various specific aptamers for different types of bacteria. The advantages and disadvantages of these electrochemical aptasensors were investigated with the aim of promoting the development and commercialization of electrochemical aptasensors for the point-of-care detection of bacteria.

We report that conjugated polymer nanoparticles (CPNs) coated with polyethylene glycols (PEGs) exhibit photothermal and photodynamic capabilities according to molecular ordering in their assembly structures. CPN-PEGs were made using three different methods: a dispersion process of phase-separated film assemblies of a conjugated polymer and a phospholipid-conjugated PEG (CPN-I), a dispersion process of a conjugated polymer and a phospholipid followed by surface conjugation with PEGs (CPN-II), and a miniemulsification of the conjugated polymer and the phospholipid-conjugated PEG. Our findings revealed that the ordered molecular assembly structures in CPN-I and CPN-II increased intermolecular interactions and decreased the optical band gap, promoting nonradiative exciton relaxation via the energy-gap law’s internal conversion mechanism and rationalizing CPN-I’s shorter singlet exciton lifetime (13 ps). Meanwhile, CPN-III with a disordered structure generated more singlet oxygen than CPN-I and CPN-II, indicating increased triplet exciton generation upon the polaron recombination. Our findings present that the photothermal and photodynamic properties of CPNs are obviously dependent on the assembly structure order and that CPNs with an ordered assembly of conjugated backbones have a stronger photothermal effect, whereas those with a disordered structure have a better photodynamic effect.