Infectious bacterial biofilms are recalcitrant to most antibiotics compared to their planktonic version, and the lack of appropriate therapeutic strategies for mitigating them poses a serious threat to clinical treatment. A ternary heterojunction material derived from a Bi-based perovskite-TiO2hybrid and a [Ru(2,2′-bpy)2(4,4′-dicarboxy-2,2′-bpy)]2+(2,2′-bpy, 2,2′-bipyridyl) as a photosensitizer (RuPS) is developed. This hybrid material is found to be capable of generating reactive oxygen species (ROS)/reactive nitrogen species (RNS) upon solar light irradiation. The aligned band edges and effective exciton dynamics between multisite heterojunctions are established by steady-state/time-resolved optical and other spectroscopic studies. Proposed mechanistic pathways for the photocatalytic generation of ROS/RNS are rationalized based on a cascade-redox processes arising from three catalytic centers. These ROS/RNS are utilized to demonstrate a proof-of-concept in treating two elusive bacterial biofilms while maintaining a high level of biocompatibility (IC50> 1 mg/mL). The in situ generation of radical species (ROS/RNS) upon photoirradiation is established with EPR spectroscopic measurements and colorimetric assays. Experimental results showed improved efficacy toward biofilm inactivation of the ternary heterojunction material as compared to their individual/binary counterparts under solar light irradiation. The multisite heterojunction formation helped with better exciton delocalization for an efficient catalytic biofilm inactivation. This was rationalized based on the favorable exciton dissociation followed by the onset of multiple oxidation and reduction sites in the ternary heterojunction. This together with exceptional photoelectric features of lead-free halide perovskites outlines a proof-of-principle demonstration in biomedical optoelectronics addressing multimodal antibiofilm/antimicrobial modality.
Bibliographical noteFunding Information:
A.D. acknowledges SERB (India) Grants CRG/2020/000492 and JCB/2017/000004 for supporting this research. S.B. acknowledges SERB (India) Grants CRG/2020/000084 and STR/2021/00000 for supporting this research. N.K. acknowledges the SRA-CSIR scientist pool scheme (13/9144-A/2020-pool). S.P.C. thanks CSIR for a Research Fellowship (File No-09/921(0180)/2017-EMR-I). K.R. acknowledges the DST/INSPIRE program for a Ph.D. fellowship (IF170004). S.K.P. acknowledges DBT Grant BT/PR22251/NNT/28/1274/2017. Su.G. and Sh.G acknowledge MoE, Government of India, IISER Kolkata and Prime Ministers Research Fellowship, respectively, for their fellowships. The research reported in this publication was also partially supported by the King Abdullah University of Science and Technology (KAUST). N.K. and S.K. acknowledge FIRST India scientific outreach forum.
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- bacterial biofilm
- bismuth perovskite halides
- ruthenium polypyridyl complex
ASJC Scopus subject areas
- General Materials Science
- General Engineering
- General Physics and Astronomy