FITC-Labeled Alendronate as an In Vivo Bone pH Sensor

  • Biomed Res Int. 2020 May 19;2020:4012194. doi: 10.1155/2020/4012194.
Yuzhou Li  1  2  3 ,  Yiru Fu  1  2  3 ,  He Zhang  1  2  3 ,  Jinlin Song  1  2  3 ,  Sheng Yang  1  2  3
Affiliations
  • 1. College of Stomatology, Chongqing Medical University, Chongqing 401147, China.
  • 2. Chongqing Key Laboratory of Oral Diseases and Biomedical Sciences, Chongqing 401147, China.
  • 3. Chongqing Municipal Key Laboratory of Oral Biomedical Engineering of Higher Education, Chongqing 401147, China.
PMID: 32550231 DOI: 10.1155/2020/4012194
Abstract

pH is a critical indicator of bone physiological function and disease status; however, noninvasive and real-time sensing of bone pH in vivo has been a challenge. Here, we synthesized a bone pH sensor by labeling alendronate with the H+-sensitive dye fluorescein isothiocyanate (Aln-FITC). Aln-FITC showed selective affinity for hydroxyapatite (HAp) rather than other calcium Materials. An in vivo biodistribution study showed that Aln-FITC can be rapidly and specifically delivered to rat Bones after caudal vein injection, and the fluorescence lasted for at least 12 h. The fluorescence intensity of Aln-FITC binding to HAp linearly decreased when the pH changed from 6 to 12. This finding was further confirmed on bone blocks and perfused bone when the pH changed from 6.8 to 7.4, indicating unique pH-responsive characteristics in the bone microenvironment. Aln-FITC was then preliminarily applied to evaluate the changes in bone pH in a nude mouse acidosis model. Our results demonstrated that Aln-FITC might have the potential for minimally invasive and real-time in vivo bone pH sensing in preclinical studies of bone healing, metabolism, and Cancer mechanisms.

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