Graphene oxide (GO) and reduced graphene oxide (RGO), due to their large active surface areas, can serve as a platform for biological molecule adhesion (both organic and inorganic). In this work we described methods of preparing composites consisting of GO and RGO and inorganic nanoparticles of specified biological properties: nanoAg, nanoAu, nanoTiO₂ and nanoAg₂O. The idea of this work was to introduce effective methods of production of these composites that could be used for future biomedical applications such as antibiotics, tissue regeneration, anticancer therapy, or bioimaging. In order to characterize the pristine graphene materials and resulting composites, we used spectroscopic techniques: XPS and Raman, microscopic techniques: SEM with and AFM, followed by X-Ray diffraction. We obtained volumetric composites of flake graphene and Ag, Au, Ag₂O, and TiO₂ nanoparticles; moreover, Ag nanoparticles were obtained using three different approaches.

This research presents an electrochemical immunosensor for collagen I detection using a self-assembled monolayer (SAM) of gold nanoparticles (AuNPs) and covalently immobilized half-reduced monoclonal antibody as a receptor; this allowed for the validation of the collagen I concentration through two different independent methods: electrochemically by Electrochemical Impedance Spectroscopy (EIS), and optically by Surface Plasmon Resonance (SPR). The high unique advantage of the proposed sensor is based on the performance of the stable covalent immobilization of the AuNPs and enzymatically reduced half-IgG collagen I antibodies, which ensured their appropriate orientation onto the sensor’s surface, good stability, and sensitivity properties. The detection of collagen type I was performed in a concentration range from 1 to 5 pg/mL. Moreover, SPR was utilized to confirm the immobilization of the monoclonal half-antibodies and sensing of collagen I versus time. Furthermore, EIS experiments revealed a limit of detection (LOD) of 0.38 pg/mL. The selectivity of the performed immunosensor was confirmed by negligible responses for BSA. The performed approach of the immunosensor is a novel, innovative attempt that enables the detection of collagen I with very high sensitivity in the range of pg/mL, which is significantly lower than the commonly used enzyme-linked immunosorbent assay (ELISA).

The wear of contacting silicon surfaces in microelectromechanical systems (MEMS) has been a longstanding concern. To address this issue, the effects of immersing silicon surfaces into alkali metal chloride solutions (LiCl, NaCl, CsCl) on their sliding friction and wear were investigated. A custom-built reciprocating tribometer was used with a sapphire ball as the counterbody. Results indicated that the friction coefficient between the silicon surface (p-doped, orientation (100)) and a sapphire ball can be reduced by up to 30% by treating the silicon surfaces in aqueous salt solutions (concentration 1 mol/L, exposure for 24 h). These modified surfaces also have higher wear resistance and a significant change in wettability. After immersion, the contact angle between the silicon surface and water was reduced by approximately 50%. These results may lead to new, simple, and inexpensive methods to increase the wear resistance of silicon surfaces for use in MEMs devices.