High performance of electrochemical and fluorescent probe by interaction of cell and bacteria with pH-sensitive polymer dots coated surfaces.

Using pH-switchable fluorescent polymer dots (PD) by means of fluorescent, colorimetric, and electrochemical signals generated from surfaces coated with PD of zwitterionic structure provided a fast and easy method to assess their performance in mammalian cell and bacterial interactions. The PD-coated surfaces showed high sensitivity over a broad range of pH levels by switching reversibly zwitterionic states, which led to an excellent cellular resistance effect by inhibiting the attachment of nearly 95% of mammalian cells. Similarly, they exhibited a strong interaction with the negatively charged surfaces of bacteria, as observed in the fluorescence ON/OFF system. In addition, PD were employed to detect the attachment of mammalian and bacterial cells: we deposited PD on a screen-printed carbon electrode for cyclic voltammetry analysis. Notably, the presence of cells remarkably interfered with the current flow between the PD and the screen-printed carbon electrode surface by causing an impressive decline in both reduction-oxidation signals, implying the high sensitivity of the PD-coated surfaces to cells and bacteria in different pH environments. Therefore, as smart materials with high sensitivity, biocompatibility, selectivity, and accuracy, PD-coated surfaces represent a promising approach to visualizing and controlling biological cell attachment, thereby helping to avoid contamination in biomedical applications.