Direct conjugation of silicon nanoparticles with M13pVIII-engineered proteins to bacteria identification

Pseudomonas aeruginosa and Staphylococcus aureus are two opportunistic human pathogens among the most common agents of nosocomial infections. The early detection plays an important role in health care, and pharmacological and biomedical sectors. The use of functional nanoparticles is promising candidate to create new materials and devices to improve diagnosis, prevention, and treatment of diseases in different fields of applications. In this work, we used phage-specific pVIII proteins, isolated from P9b and St.au9IVS5 phage clones, displaying exogenous peptide (QRKLAAKLT and RVRSAPSSS) to detect P. aeruginosa and S. aureus, respectively. These selective bioprobes were used in “one-step” functionalization of silicon nanoparticles (SiNPs) by pulsed laser ablation of silicon in an aqueous solution, containing phage-specific pVIII protein. The optical properties of the bioconjugates (pVIII–SiNPs) are examined by photoluminescence and UV–Vis spectroscopy. Furthermore, size distribution and ability of bioconjugates to bind its bacterial target has been investigated by scanning electron microscopy, scanning transmission electron microscopy, and epi-fluorescence microscope. Our results show that the bioconjugates are able to bind P. aeruginosa and S. aureus, respectively, within 30 min. Furthermore, the yellow–green photo-emissive properties, detected by epi-fluorescence microscopy, demonstrate their potential use as fluorescent probes silicon-based for in vitro applications.