Physical adsorption of protamine for heparin assay using a quartz crystal microbalance and electrochemical impedance spectroscopy

Tzong Jih Cheng, Tsun Mei Lin, Hsien Chang Chang

Research output: Contribution to journalArticlepeer-review

30 Citations (Scopus)

Abstract

This study attempted to determine absolute heparin concentration in phosphate buffer solution (PBS, pH 7.4) by using quartz crystal microbalance (QCM) as an affinity biosensor. Electrochemical impedance spectroscopy (EIS) was also used to investigate immobilization of protamine and heparin assay. In addition, the effectiveness of physical adsorption in immobilizing protamine was confirmed by examining the preparation conditions, including the incubation time and protamine concentration. It induced maximum decrease (ca. -100Hz) in oscillating frequency of QCM by applying 20mg/ml protamine and 20min for incubation in PBS. Heparin adsorption onto protamine-modified electrode in PBS revealed an exponential-like binding curve and long duration for reaching the steady state in frequency response of QCM. Moreover, two linear calibration curves were obtained judging from the initial slope (df/dt) and the frequency change (Δf) of QCM obtained after a binding interval (600s) for heparin concentrations from 0 to 3.0 and 7.0U/ml, respectively. In EIS analysis, calibration curves with linear concentration range of 0-3.0U/ml were obtained for heparin in PBS when ferrocyanide was used as an electroactive marker.

Original languageEnglish
Pages (from-to)261-273
Number of pages13
JournalAnalytica Chimica Acta
Volume462
Issue number2
DOIs
Publication statusPublished - 2002 Jul 1

All Science Journal Classification (ASJC) codes

  • Analytical Chemistry
  • Biochemistry
  • Environmental Chemistry
  • Spectroscopy

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