Superior Peroxidase-Like Activity of Gold Nanorattles in Ultrasensitive H2 O2 Sensing and Antioxidant Screening.

Nanozymes are artificial enzyme systems which are easy to produce, highly stable and cost-effective in comparison to natural enzymes. Herein, we evaluated the peroxidase-like activity of gold nanorattles (Au NRTs) having a solid gold octahedron core and thin, porous cubic gold shell. We also prepared solid gold nanocubes and nanospheres of similar sizes and surface charge as that of Au NRTs and compared their activity with standard horse radish peroxidase (HRP). All the prepared nanostructures followed Michaelis-Menten kinetics as observed from their substrate concentration vs. initial reaction velocity plot using 3,3',5,5'-tetramethylbenzidine (TMB) as a substrate. The kinetic parameters and the catalytic efficiency for the peroxidase-like activity of the nanostructures and HRP were calculated, and it was observed that Au NRTs possess the best nanozymatic activity with lowest KM and highest catalytic efficiency (kcat /KM ). The better activity of Au NRTs compared with other nanostructures and HRP could be attributed to the hollow porous structure with a solid core where different surfaces are available for reaction. Au NRTs, being the best amongst the tested nanozymes were further used for the sensing of hydrogen peroxide (H2 O2 ) and were found to sense H2 O2 down to 0.5 µM. Further, two naturally occurring antioxidants, tannic acid and ascorbic acid showed inhibitory effect on the peroxidase-like activity of Au NRTs in a concentration dependent manner which can be further used for screening of antioxidants or for determining the antioxidant potential.

A review of recent advances in magnetic nanoparticle-based theranostics of glioblastoma.

Rapid vascular growth, infiltrative cells and high tumor heterogenicity are some glioblastoma multiforme (GBM) characteristics, making it the most lethal form of brain cancer. Low efficacy of the conventional treatment modalities leads to rampant disease progression and a median survival of 15 months. Magnetic nanoparticles (MNPs), due to their unique physical features/inherent abilities, have emerged as a suitable theranostic platform for targeted GBM treatment. Thus, new strategies are being designed to enhance the efficiency of existing therapeutic techniques such as chemotherapy, radiotherapy, and so on, using MNPs. Herein, the limitations of the current therapeutic strategies, the role of MNPs in mitigating those inadequacies, recent advances in the MNP-based theranostics of GBM and possible future directions are discussed.

Lay abstract Glioblastoma multiforme is the most aggressive and deadly form of brain cancer. Currently available treatment methods such as chemotherapy, surgery and radiotherapy are not often successful. This leads to fast disease progression and a maximum survival of 15 months. Magnetic nanoparticles, due to their unique features, could be a suitable tool for treating and diagnosing glioblastoma. This review article discusses their potential in this field.