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Mechanistic insights into synergistic and antagonistic effects of nanoplastics on antibiotic toxicities via a Biospectroscopy-Bioreporter Coupling (BBC) approach
Summary
Researchers used a novel approach combining bioreporters and Raman spectroscopy to study how nanoplastics interact with common antibiotics. They found that nanoplastics can either reduce or amplify antibiotic toxicity depending on the specific antibiotic involved, acting as absorbers that lower toxicity for some drugs while serving as carriers that increase cellular uptake and damage for others. The findings highlight the complex and unpredictable ways that nanoplastics and pharmaceutical contaminants may interact in the environment.
The co-occurrence of nanoplastics (NPs) and antibiotics poses emerging and complex toxicological challenges. In this study, we combined whole-cell bioreporter (Acinetobacter baylyi ADPWH_recA) and Raman biospectroscopy to evaluate cytotoxicity and genotoxicity induced by three representative antibiotics of amoxicillin, ciprofloxacin, and tetracycline at environmentally relevant concentrations (0.01-1 mg/L), in the presence of 80-nm pristine (PS), UV-aged (uvPS), and freeze-thaw-aged (ftPS) polystyrene NPs. Amoxicillin and tetracycline alone induced cytotoxicity, whereas ciprofloxacin exhibited pronounced genotoxicity and elevated intracellular reactive oxygen species. Raman biomarkers (e.g., 1122, 1210, 1386 and 1700 cm) revealed distinct mechanisms involving membrane disruption, DNA damage, and lipid disorder. PS-NPs modulated antibiotic toxicity in a concentration- and type-dependent manner, acting as either adsorbents (antagonism) or nanocarriers (synergism). For cytotoxic antibiotics such as amoxicillin and tetracycline, PS-NPs primarily functioned as adsorbents, reducing bioavailability and mitigating toxicity. In contrast, for ciprofloxacin, which targets intracellular components, PS-NPs enhanced cellular uptake and exacerbated genotoxicity. A random forest model integrating spectral features achieved a classification accuracy of over 93 % and enabled the source-apportionment of toxicity, elucidating the dual roles of PS-NPs as both adsorbents and nanocarriers. These findings provide mechanistic insights into the interplay between nanoplastics and antibiotics, demonstrating the efficacy of the Biospectroscopy-Bioreporter Coupling (BBC) strategy for risk assessment of emerging contaminants.