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We report on the synthesis, characterization, and application of biomimetic, spherical Au nanoparticles (AuNPs) coated with keratin (Ker-AuNPs). They are characterized in terms of morphological, spectral, and thermo-optical properties. Besides their excellent colloidal stability, Ker-AuNPs exhibit excellent biocompatibility. The latter is verified by performing viability assay experiments of a strain of Escherichia coli (E. coli) in the presence of Ker-AuNPs as a function of the incubation time. Ker-AuNPs do not affect the E. coli viability and proliferation, even at the highest concentration tested (C = 5.83*10−5 M). Photo-thermal assisted viability experiments are performed by setting the starting temperature at 37 °C, mimicking the normal human body temperature condition. They evidence the capability of the Ker-AuNPs to generate a temperature up to about 73 °C (an increase of 36 °C), thus reducing the viability of bacterial cells 3 order of magnitudes. We also conducted a theoretical analysis with an ad-hoc model that evidences an excellent agreement between theory and experiments. Ker-AuNPs represent a new generation of multifunctional nanotherapeutics, and they constitute a new opportunity in drug-free and minimally invasive biomedical applications. [Display omitted] [ABSTRACT FROM AUTHOR]

Antibiotic resistance refers to when microorganisms survive and grow in the presence of specific antibiotics, a phenomenon mainly related to the indiscriminate widespread use and abuse of antibiotics. In this framework, thanks to the design and fabrication of original functional nanomaterials, nanotechnology offers a powerful weapon against several diseases such as cancer and pathogenic illness. Smart nanomaterials, such as metallic nanoparticles and semiconductor nanocrystals, enable the realization of novel drug-free medical therapies for fighting against antibiotic-resistant bacteria. In the light of the latest developments, we highlight the outstanding capabilities of several nanotechnology-inspired approaches to kill antibiotic-resistant bacteria. Chemically functionalized silver and titanium dioxide nanoparticles have been employed for their intrinsic toxicity, which enables them to exhibit an antimicrobial activity while, in a different approach, photo-thermal properties of metallic nanoparticles have been theoretically studied and experimentally tested against several temperature sensitive (mesophilic) bacteria. We also show that it is possible to combine a highly localized targeting with a plasmonic-based heating therapy by properly functionalizing nanoparticle surfaces with covalently linked antibodies. As a perspective, the utilization of properly engineered and chemically functionalized nanomaterials opens a new roads for realizing antibiotic free treatments against pathogens and related diseases. [ABSTRACT FROM AUTHOR]