title: Detection of residual rifampicin in urine via fluorescence quenching of gold nanoclusters on paper.
abstract: BACKGROUND
  Rifampicin or rifampin (R) is a common drug used to treat inactive meningitis, cholestatic pruritus and tuberculosis (TB), and it is generally prescribed for long-term administration under regulated dosages. Constant monitoring of rifampicin is important for controlling the side effects and preventing overdose caused by chronic medication. In this study, we present an easy to use, effective and less costly method for detecting residual rifampicin in urine samples using protein (bovine serum albumin, BSA)-stabilized gold nanoclusters (BSA-Au NCs) adsorbed on a paper substrate in which the concentration of rifampicin in urine can be detected via fluorescence quenching. The intensity of the colorimetric assay performed on the paper-based platforms can be easily captured using a digital camera and subsequently analyzed.
  
  
  RESULTS
  The decreased fluorescence intensity of BSA-Au NCs in the presence of rifampicin allows for the sensitive detection of rifampicin in a range from 0.5 to 823 µg/mL. The detection limit for rifampicin was measured as 70 ng/mL. The BSA-Au NCs were immobilized on a wax-printed paper-based platform and used to conduct real-time monitoring of rifampicin in urine.
  
  
  CONCLUSIONS
  We have developed a robust, cost-effective, and portable point-of-care medical diagnostic platform for the detection of rifampicin in urine based on the ability of rifampicin to quench the fluorescence of immobilized BSA-Au NCs on wax-printed papers. The paper-based assay can be further used for the detection of other specific analytes via surface modification of the BSA in BSA-Au NCs and offers a useful tool for monitoring other diseases.
authors.affiliation: Department of Engineering and System Science, National Tsing Hua University, Hsinchu, 300, Taiwan. sanu.hit@gmail.com.|Nano Science and Technology Program, Taiwan International Graduate Program, Academia Sinica, Taipei, 115, Taiwan. sanu.hit@gmail.com.|National Tsing Hua University, Hsinchu, 300, Taiwan. sanu.hit@gmail.com.|Research Center for Applied Sciences, Academia Sinica, Taipei, 115, Taiwan, ROC. sanu.hit@gmail.com.
authors.forename: Krishnendu
authors.initials: K
authors.lastname: Chatterjee
authors.affiliation: Research Center for Applied Sciences, Academia Sinica, Taipei, 115, Taiwan, ROC. kuo55@gate.sinica.edu.tw.
authors.forename: Chiung Wen
authors.initials: CW
authors.lastname: Kuo
authors.affiliation: Department of Pathology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan. doc31717@ndmctsgh.edu.tw.
authors.forename: Ann
authors.initials: A
authors.lastname: Chen
authors.affiliation: Research Center for Applied Sciences, Academia Sinica, Taipei, 115, Taiwan, ROC. peilin@gate.sinica.edu.tw.
authors.forename: Peilin
authors.initials: P
authors.lastname: Chen
mesh_terms: D000818:Animals; D000904:Antibiotics, Antitubercular / Q000652:urine*; D015374:Biosensing Techniques / Q000379:methods; D002417:Cattle; D006046:Gold / Q000737:chemistry*; D006801:Humans; D057230:Limit of Detection; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D010209:Paper; D019095:Point-of-Care Systems; D012293:Rifampin / Q000652:urine*; D012710:Serum Albumin, Bovine / Q000737:chemistry; D013050:Spectrometry, Fluorescence / Q000379:methods*
chemical_list: D000904:Antibiotics, Antitubercular; D012710:Serum Albumin, Bovine; D006046:Gold; D012293:Rifampin