Quaternary nitrogen heterocyclic boronic acid-containing compounds are described, which are sensitive to glucose and fructose, as well as a variety of other physiologically important analytes, such as aqueous chloride and iodide, and a method of using the compounds. Also disclosed is a contact lens doped with the quaternary nitrogen heterocyclic boronic acid-containing compound, and a method of using the doped contact lens to measure the concentration of analyte in tears under physiological conditions.