Coating gold nanorods with silica prevents the generation of reactive oxygen species under laser light irradiation for safe biomedical applications

Gold nanoparticles can produce reactive oxygen species (ROS) under the action of ultrashort pulsed light. While beneficial for photodynamic therapy, this phenomenon is prohibitive for other biomedical applications such as...

Antibacterial and Antibiofilm Activity of Mercaptophenol Functionalized-Gold Nanorods Against a Clinical Isolate of Methicillin-Resistant Staphylococcus Aureus

Gold nanorods (AuNRs) were synthesized and surface functionalized with 4-mercaptophenol (4-MPH) ligand. The surface-functionalized AuNRs, 4-MPH-AuNRs, were characterized by UV-Vis spectroscopy, dynamic light scattering (DLS), transmission electron microscopy (TEM) imaging, zeta potential, and Fourier-Transformed Infrared (FTIR) spectroscopy. The antibacterial and antibiofilm activities of 4-MPH-AuNRs were evaluated against a clinical isolate of Methicillin-Resistant Staphylococcus aureus (MRSA). The results indicate that the surface-modified nanorods, 4-MPH-AuNRs, exhibit a bactericidal activity with a minimum inhibitory concentration (MIC) of ~6.25 \(\mu\)g/ml against a planktonic suspension of MRSA. Furthermore, 4-MPH-AuNRs resulted in 2-3 log-cycle reduction of MRSA biofilm viable count over a concentration range of 100-4.0 \(\mu\)g/ml. The bacterial uptake of surface-modified nanorods was investigated by inductively coupled plasma-optical emission spectroscopy (ICP-OES) and scanning electron microscopy (SEM) imaging; the results reveal that ~27% of the nanorods were internalized into the bacterial cells after 6 hrs of exposure. SEM imaging revealed a significant accumulation of the nanorods at the bacterial cell wall and a possible cellular internalization. Thus, 4-MPH-AuNRs can be considered a potential novel antibacterial agent, particularly against resistant MRSA strain biofilm.

Delivery of siRNA Using Functionalized Gold Nanorods Enhances Anti-Osteosarcoma Efficacy

Gold nanorods (GNRs) are intensively explored for the application in cancer therapy, which has motivated the development of photothermal therapy (PTT) multifunctional nanoplatforms based on GNRs to cure osteosarcoma (OS). However, the major limitations include the toxicity of surface protectants of GNRs, unsatisfactory targeting therapy, and the resistant effects of photothermal-induced autophagy, so the risk of relapse and metastasis of OS increase. In the present study, the GNR multifunctional nanoplatforms were designed and synthesized to deliver transcription factor EB (TFEB)-siRNA–targeting autophagy; then, the resistance of autophagy to PTT and the pH-sensitive cell-penetrating membrane peptide (CPP) was weakened, which could improve the tumor-targeting ability of the GNR nanoplatforms and realize an efficient synergistic effect for tumor treatment. Meanwhile, it is worth noting that the GNR nanoplatform groups have anti-lung metastasis of OS. This study provides a new reference to improve the efficacy of OS clinically.