Guanidinium-Functionalized Polymer Dielectrics for Triboelectric Bacterial Detection.

Development of rapid detection strategies that target potentially pathogenic bacteria has gained increasing attention due to the increasing awareness for better health and safety. In this study, we evaluate an intrinsically antimicrobial polymer, 2Gdm, which is a poly(norbornene)-based functional polymer featuring guanidinium groups as side chains, for bacterial detection by the means of triboelectric nanogenerators (TENGs) and triboelectric nanosensors (TENSs). Attachment of bacteria to the sensing layer is anticipated to alter the overall triboelectric properties of the underlying polymer layer. The positively charged guanidinium functional groups can interact with the negatively charged phospholipid bilayer of bacteria and lead to bacterial death, which can then be detected by optical microscopy, X-ray photoelectron microscopy, and more advanced self-powered sensing techniques such as TENGs and TENSs. The double bonds present along the poly(norbornene) backbone allow for thermally induced cross-linking to obtain X-2Gdm and thus rendering materials remain stable in water. By monitoring the change in voltage output after immersion in various concentrations of Gram-negative Escherichia coli (E. coli) and Gram-positive Streptococcus pneumoniae (S. pneumoniae), we have demonstrated the utility of X-2Gdm as a new polymer dielectric for autonomous bacterial detection. As the bacterial concentration increases, the amount of adsorbed bacteria also increases, resulting in a decrease in the surface potential of the X-2Gdm thin film; this reduction in surface potential can cause a decrease in the triboelectric output for both TENGs and TENSs, which serves as a key working mechanism for facile bacterial detection. TENG and TENS systems are capable of detecting E. coli and S. pneumoniae within a range of 4 × 105 to 4 × 108 CFU/mL with a limit of detection of 106 CFU/mL. This report highlights the promising prospects of employing TENGs and TENSs as innovative sensing technologies for rapid bacterial detection by leveraging the electrostatic interactions between bacterial cell membranes and cationic groups present on polymer surfaces.

Antrodia camphorata polysaccharides exhibit anti-hepatitis B virus effects.

Polysaccharides were extracted from fruiting bodies and cultured mycelia from five Antrodia camphorata strains. Polysaccharide profiles of the five strains, as determined by high-performance anion-exchange chromatography, showed varying yields and composition of neutral sugars. A. camphorata fruiting bodies also had different polysaccharide patterns compared to the cultured mycelium. Analysis of 26-day-old mycelia showed that the neutral sugars galactose, glucose, mannose, and galactosamine were predominant. All mycelia polysaccharide preparations exhibited anti-hepatitis B virus activity. Polysaccharides from strain B86 at a concentration of 50 microg ml(-1) showed the highest level of anti-hepatitis B surface antigen effect, which was higher than alpha-interferon at a dosage of 1000 U ml(-1). Only strains B86 and 35398 had substantial anti-hepatitis B e antigen activities. None of the polysaccharides exhibited cytotoxic effects.