Search

Silver nanoclusters (AgNCs) stabilized by DNA are promising materials with tunable fluorescent properties, which have been employed in a plethora of sensing systems. In this report, we explore their antimicrobial properties in Gram-positive and Gram-negative bacteria. After testing 9 oligonucleotides with different sequence and length, we found that the antibacterial activity depends on the sequence of the oligonucleotide employed. The sequences tested yielded fluorescent AgNCs, which can be grouped in blue, yellow, and red emitters. Interestingly, blue emitters yielded poor antibacterial activity, whereas yellow and red emitters afforded an activity similar to silver nitrate. Furthermore, structural studies using circular dichroism indicate the formation of complexes with different stability and structure, which might be one of the factors that modulate their activity. Finally, we prepared a trimeric structure containing the sequence that afforded the best antimicrobial activity, which inhibited the growth of Gram-positive and negative bacteria in the submicromolar range.

Over the past few years, several types of radiosensitizers have been developed to address the challenges of tumor hypoxia in favor of cancer radiotherapy. In this study, we aimed to synthesize a nano-radiosensitizers via conjugation of metronidazole (Met) to bovine serum albumin coated bismuth sulfide nanoparticles (Bi2S3@BSA NPs), named Bi2S3@BSA-Met. The NPs were characterized with different techniques. Bi2S3@BSA-Met NPs were shown to have a mean hydrodynamic particle size around 154 nm and a spherical shape with homogenous size distribution. Apoptosis assay revealed that the combination of Bi2S3@BSA-Met NPs with X-Ray irradiation potentiated the cell apoptotic rate. Furthermore, one of the most striking results to emerge from the data comparison was the effects of Met on radiosensitization of 4T1 cells under hypoxia condition. Conjugation of Met to Bi2S3@BSA NPs resulted in superior cell cytotoxicity upon X-ray irradiation. Results provide unprecedented evidence for the potential capability of Met as an effective radiation sensitizer for hypoxic tumor cells.