Related Experiment Video
Updated: Feb 6, 2026

Synthesis and Operation of Fluorescent-core Microcavities for Refractometric Sensing
Published on: March 13, 2013
Strong binding and fluorescence sensing of bisphosphonates by guanidinium-modified calix[5]arene
Jie Gao1, Zhe Zheng1, Lin Shi1
1College of Chemistry, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), Nankai University, Tianjin 300071, China.
Abstract:
Based on the indicator displacement assay (IDA) approach, we herein report the fluorescence "switch-on" sensing and quantitative detection of bisphosphonates (BPs), a class of drugs extensively used in the treatment of patients with various skeletal diseases. Guanidinium-modified calix[5]arene (GC5A) affords strong binding on the micromolar to nanomolar level towards BPs dominantly via multiple salt bridge interactions, which was evaluated by fluorescence competitive titrations. Fluorescent IDA enables the highly sensitive and label-free detection of BPs in buffer solution, and more importantly, in artificial urine. Calibration lines were therefore set up in untreated artificial urine, allowing for quantifying the concentrations of BPs in the biologically relevant low range.
Related Concept Videos
Titration Calculations: Strong Acid - Strong Base
A titration is carried out for 25.00 mL of 0.100 M HCl (strong acid) with 0.100 M of a strong base NaOH. The pH at different volumes of added base solution can be calculated as follows:
(a) Titrant volume = 0 mL. The solution pH is due to the acid ionization of HCl. Because this is a strong acid, the ionization is complete and the hydronium ion molarity is 0.100 M. The pH of the solution is then:
Strong Acid and Base Solutions
Titration of a Strong Acid with a Strong Base
The Equilibrium Binding Constant and Binding Strength
The Sense of Self: Reflected Self-Appraisal and Social Comparison
5-Number Summary
In a box plot, the minimum and maximum data values represent the lower and upper whiskers in the graph, and the median is designated as the center of the box in the chart. The first quartile and third...

