Interactions between sulfonamide antibiotics and metal ions: does toxicity increase or decrease?

Area of Science:

• Environmental Chemistry
• Aquatic Toxicology
• Spectroscopy

Background:

• Coexistence of antibiotics and metal ions is common in aquatic environments.
• Understanding combined effects of these contaminants is crucial for environmental risk assessment.
• Effects of antibiotic-metal interactions on photochemical behavior and toxicity are not well understood.

Purpose of the Study:

• Investigate spectroscopic changes and toxicity of sulfonamide antibiotics (SDZ, SMX) upon binding with metal ions (Fe(iii), Al(iii), Cu(ii)).
• Evaluate how metal binding influences the physicochemical properties and biological toxicity of sulfonamides.
• Assess implications for contaminant fate and remediation in aquatic ecosystems.

Main Methods:

• Fourier-transform infrared (FTIR) spectroscopy to identify metal binding sites.
• UV-vis spectroscopy to analyze spectral shifts and electronic environment changes.
• Vibrio fischeri bioluminescence inhibition assay for toxicity evaluation.

Main Results:

• Metal binding altered UV-vis spectra and fluorescence intensity of sulfonamides.
• Interaction strength followed Fe(iii) > Cu(ii) > Al(iii).
• Sulfonamide toxicity generally decreased after metal binding, especially when metal ion toxicity was high.

Conclusions:

• Metal-sulfonamide interactions significantly modify spectroscopic characteristics and reduce biological toxicity.
• These interactions impact contaminant bioavailability, environmental risk, and remediation strategies.
• Further research is needed to fully understand the environmental fate of coexisting contaminants.