In recent years, conducting polymer (CP) nanomaterials have been used in a variety of fields, such as in energy, environmental, and biomedical applications, owing to their outstanding chemical and physical properties compared to conventional metal materials. In particular, nanobiosensors based on CP nanomaterials exhibit excellent performance sensing target molecules. The performance of CP nanobiosensors varies based on their size, shape, conductivity, and morphology, among other characteristics. Therefore, in this review, we provide an overview of the techniques commonly used to fabricate novel CP nanomaterials and their biosensor applications, including aptasensors, field-effect transistor (FET) biosensors, human sense mimicking biosensors, and immunoassays. We also discuss prospects for state-of-the-art nanobiosensors using CP nanomaterials by focusing on strategies to overcome the current limitations.

Triplet–triplet annihilation upconversion (TTA-UC) has been attracting attention in various fields as a promising tool to efficiently generate a shorter-wavelength photon than incident light. Compared to conventional UC technologies (e.g., lanthanide-doped inorganic nanoparticles), TTA-UC has advantages of tunable spectral range and high UC efficiency (>1–40%) at non-coherent solar irradiance (I_ex < 1–10² mW cm⁻²). This review article provides a succinct overview of the historical background and recent strategies for solving a critical problem (i.e. oxygen quenching) of TTA-UC to improve the efficiency and to expand its applicability in various fields. We also introduce recent strategies to develop host materials (e.g., films, polymers, nanocapsules, gels) for overcoming a quenching problem, before we detail recent progress in applications of TTA-UC materials involving bioimaging, biomedicines, photocatalysts, photovoltaics and OLEDs. This review article aims to highlight the challenges and recent advances in the field of TTA-UC, providing the readers with guidance and opportunities to join the research.