The use of 111Ag as a tool for studying biological distribution of silver-based antimicrobials

Abstract

Recently, there has been an emergence of significant interest in silver-based antimicrobials. Our goal was to develop a radioactive tracer for investigating the biological fate of such compounds. Purified 111Ag was incorporated into the methylated caffeine analogue, IC1 to yield the silver carbene complex designated as [111Ag]SCC1 and investigated in biodistribution studies.

Investigating the pharmacokinetics and biological distribution of silver‐loaded polyphosphoester‐based nanoparticles using 111Ag as a radiotracer

“…111 Ag has a t ½ = 7.47 days, decays 92% by β − emission (1.037 MeV) and has characteristic γ rays at energies of 245 keV (1.3%) and 342 keV (6.7%) useful for detection and monitoring by gamma spectroscopy. [21, 25] The average recovery of purified 111 Ag was 92.9 ± 23.7% from the palladium target as assessed by comparing the activity measured before and after purification via gamma spectrometry. ICP-MS measurement of the eluted fractions demonstrated a final concentration of <25 ppb of Pd in all solutions used for subsequent radiolabeling which indicated that >99.9% of the palladium was removed by our purification process.…”

“…[21] Silver acetate and diethyl ether were purchased from Sigma-Aldrich (Milwaukee, WI). Other solvents were obtained from Fisher (Pittsburgh, PA) or Burdick and Jackson (Morristown, NJ).…”

“…[21, 22] Briefly, irradiated Palladium wire (4 – 6 mg Pd, 111 Ag ranging from 44.4 to 118.4 MBq) was dissolved in 2 mL of a conc. HCl: conc.…”

“…Isolation of 111 Ag from the dissolved palladium wire target was achieved with the anion exchange AG1-X8 resin using a method described by Aardaneh et al [24] Briefly, as described in the modified method, [21] 4.7 g of AG1-X8 resin was made into a slurry with 3 M HNO 3 and loaded into a Flex column (0.7 × 20 cm) and conditioned further with 15 mL of 3 M HNO 3 . Typically, 2.5 - 2.7 mL of dissolved Pd wire- 111 Ag target in 3 M HNO 3 was loaded onto the resin and eluted with 3 M HNO 3 in 1 mL fractions.…”

“…Synthesis of the carbene compound known as imidazolium complex 1, IC1 (a precursor for SCC1), was accomplished as previously described by Kascatan-Nebioglu et al , [6] and the synthesis of [ 111 Ag]SCC1 was performed as previously published. [21] Briefly, the carbene compound, IC1 (32 mg, 0.095 mmol) was dissolved in 1 mL of methanol before adding into a vial containing dried 111 Ag. This mixture was stirred for 10 min to resuspend the 111 Ag.…”