Multidrug resistant bacteria are a long-standing public health emergency, and Ag+ is a powerful tool to treat multidrug resistant bacteria by disrupting metabolism and disulfide bond formation. Currently silver-based treatments use silver salts or colloidal silver, which suffer from both local and systemic toxicity concerns. In addition, there are few tools to effectively monitor and trigger Ag+ release. Photoacoustic (PA) imaging is an excellent noninvasive imaging modality, and gold nanorods (AuNR) are a powerful photoacoustic contrast agent due to their tunable absorption spectra and high absorption cross section. Previously, we developed Ag-coated AuNR hybrid particles (Ag/AuNR) that showed selective etching of Ag with 5-30 mM H2O2. We now extend this to include a silver shell doped with iodide to increase its etching sensitivity to H2O2. Doping iodide decreases the reduction potential of Ag from E0Ag = 0.69 V to EoAgI = - 0.15 V causing a 10-fold increase in H2O2 sensitivity. The as-prepared silver iodide coated gold nanorods (AgI/AuNR) are stable under ambient conditions and show selective etching of Ag between 0.1-1 mM of H2O2. Uncoated AuNR have a peak absorbance at 700 nm whereas AgI/AuNR show a blue shift to 644 nm. Treating AgI/AuNR with varying concentrations of H2O2 shows recovery of the 700 nm peak and selective etching of silver from the gold core. This was further confirmed by transmission electron microscopy. The PA signal is also recovered post etching. Kinetic studies show that the AgI/AuNR show faster etching with the same concentration of H2O2 versus Ag/AuNR. Future work will evaluate these materials as a bactericidal agent.

Iodide-doped gold/silver hybrid nanorods report reactive oxygen species concentrations via photoacoustic imaging

2019 Fall National Meeting

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