Keratin is a structural protein of mammalian tissues and birds, representing the principal constituent of hair, nails, skin, wool, hooves, horns, beaks, and feathers, and playing an essential role in protecting the body from external harassment. Due to its intrinsic features such as biocompatibility, biodegradability, responsiveness to specific biological environment, and physical–chemical properties, keratin has been extensively explored in the production of nanocarriers of active principles for different biomedical applications. In the present review paper, we aimed to give a literature overview of keratin-based nanoparticles produced starting from human hair, wool, and chicken feathers. Along with the chemical and structural description of keratin nanoparticles, selected in vitro and in vivo biological data are also discussed to provide a more comprehensive framework of possible fields of application of this protein. Despite the considerable number of papers describing the production and use of keratin nanoparticles as carries of anticancer and antimicrobial drugs or as hemostatic and wound healing materials, still, efforts are needed to implement keratin nanoparticles towards their clinical application.

We studied the chemical-physics and the nature of the interactions involved in the formation of adducts of two-dimensional black phosphorus (2D BP) with organoboron derivatives of a conjugated fluorescent molecule (pyrene). Time-resolved fluorescence spectroscopy showed a stabilization effect of 2D BP on all the organoboron derivatives, in particular for the adducts endowed with the boronic functionalities. Also, a stronger modulation of the fluorescence decay with oxygen was registered for one of the adducts compared to the corresponding organoboron derivative alone. NMR experiments in suspension and DFT simulations confirmed that only non-covalent interactions are involved in the formation of the adducts. The energetic gain in their formation arises from the interaction of P atoms with both C atoms of the pyrene core and with B atom of the boronic functionalities, with a stronger contribution from the ester with respect to the acid one. The interaction results in a lowering of the band gap of 2D BP by around 0.10 eV. Furthermore, we demonstrated through Raman spectroscopy an increased stability towards oxidation in air of 2D BP in the adducts in the solid state (more than six months). The modification of the electronic structure at the interface between 2D BP and a conjugated organic molecule through non-covalent stabilizing interactions mediated by the B atom is particularly appealing in view of creating heterojunctions for optoelectronic, photonic and chemical sensing applications.