(001) facet-supported TiO 2 facet heterojunction with abundant active sites and high-efficiency carrier separation for ultrasensitive SERS detection of antibiotic residues in foods.

Background: Antibiotic residues in animal-derived foods are seriously threatening human health and have attracted growing public attention. It is very important and valuable to carry out a rapid ultrasensitive detection of antibiotic residues, especially accurate identification based on molecular fingerprints.
Results: Here, a (001) facet-supported TiO ₂ facet heterojunction with abundant active sites (SF-TiO ₂ ) was developed as a surface-enhanced Raman scattering (SERS) substrate for ultrasensitive detection of antibiotic residues in milk and honey foods. Exposure of more (001) facets in SF-TiO ₂ can not only provide abundant surface-active sites for efficient chemical recognition of target molecules, but also form effective facet heterojunctions to achieve high-efficient carrier separation for charge transfer between substrate and molecule, which are together responsible for ultrasensitive SERS detection of target molecules with an enhancement factor of 1.3 × 10 ⁷ . The detection limit of enrofloxacin, enoxacin, ciprofloxacin and chloramphenicol residues in milk or honey reaches to 10 ^-10 -10 ^-9  M, far lower than the EU standard. And, a simultaneous identification of multi-component residues in foods can be realized. The developed substrate exhibits excellent stability, anti-interference ability, and recyclability in the actual detection.
Significance: This work not only provides a novel SERS method for ultrasensitive detection of antibiotic residues in animal-derived foods, but also provides new ideas and concepts for the development of new-type semiconductor SERS substrates and their practical application.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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