*5.1. Biosensors*

BP is a good candidate for several strategic applications in the biomedical sector (Figure 3). Properties such as biocompatibility, biodegradability, and biosafety are essential for use in medicine. As will be further described, recent studies on BP have shown it to be among the 2D materials which are applicable in more than one biomedical field. Its use has been considered in the therapeutic, in imaging, pharmacological, and diagnostic fields, as well as in the realization of biosensors, and in bio-printing. Wang et al. highlighted the excellent optical properties of BP in phototherapy. In fact, BP can be used as nanoagen<sup>t</sup> in vivo, which, during irradiation with NIR light, can selectively kill tumor cells within a well-defined time (typically, 8–10 min). As confirmation of recent in vitro studies reporting interesting proof of its use in oncology, the behavior of BP in oncological phototherapy showed an efficiency higher than those of other traditional photothermic agents. Another application is related to photoacoustic imaging, in which BP was combined with TiL4 to be used as an exogenous agent. The TiL4-BP combination has made it possible to obtain better stability in water, avoiding degradation issues [27]. Also, BP has been shown to have electrochemical, fluorescent, and electrical properties, which may make it suitable for use in biosensors-related technologies. Many applications in the clinical field involve the use of technologies which are able to define the concentrations of certain substances in biological fluids, e.g., in human blood. BP nanosheets and nanoparticles are often used in the realization of sensors inside analytical instruments. Typically, a biosensor made of BP is used for the detection of immunoglobulins, cardiac markers, and early oncological markers [13]. In 2016, Sofer et al., studying the properties of BP nanosheets, reported excellent results after combining gold nanoparticles with BP sheets. The presence of BP increased the already excellent conductivity of gold, also increasing its sensitivity in detecting poorly circulating biomarkers [28]. Many sensors for medical applications can also detect several substances in healthcare environments. The BPQD (BP Quantum Dose) is used for devices which are able to detect humidity in medical equipment, such as sterilizers, incubators, and surgical instruments [13].
