Gemcitabine Direct Electrochemical Detection from Pharmaceutical Formulations Using a Boron-Doped Diamond Electrode

At a Glance

Metadata	Details
Publication Date	2021-09-10
Journal	Pharmaceuticals
Authors	Iulia Rus, Alexandra Pusta, Mihaela Tertiş, Cristina Barbălată, Ioan Tomuță
Institutions	Iuliu Hațieganu University of Medicine and Pharmacy
Citations	15
Analysis	Full AI Review Included

Executive Summary

Core Achievement: A simple, fast, and direct electrochemical method was successfully developed for the quantification of the chemotherapeutic drug Gemcitabine (GMB) using a Boron-Doped Diamond Electrode (BDDE).
Electrode Performance: BDDE enabled the detection of GMB via irreversible anodic oxidation at approximately 2.2 V vs. Ag/AgCl, a potential range where conventional electrodes (GCE, AuE, SPEs) failed to show a signal.
Mechanism: Scan rate studies confirmed the electrochemical oxidation process is primarily diffusion-controlled, suggesting high stability and reproducibility.
High Sensitivity (Amperometry): The optimized amperometric technique (AMP) achieved a low limit of detection (LOD) of 0.15 µg/mL, covering a wide linear range of 0.5-65 µg/mL, making it suitable for sensitive analysis.
Voltammetry Utility: Differential Pulse Voltammetry (DPV) was optimized for physiological conditions (PBS pH 7.4), offering an LOD of 0.85 µg/mL and a linear range of 2.5-50 µg/mL, ideal for rapid quality control.
Validation and Robustness: Both DPV and AMP methods showed excellent recovery rates and strong statistical correlation (Bland-Altman analysis) with established control methods (HPLC-UV and UV-Vis spectrophotometry).
Value Proposition: The BDDE methods offer a robust, low-cost, and rapid alternative (30 s for DPV, 300 s for AMP) to complex chromatographic techniques for pharmaceutical quality control.

Technical Specifications

Parameter	Value	Unit	Context
Working Electrode Material	Boron-Doped Diamond (BDDE)	N/A	3-mm diameter
GMB Oxidation Potential	~2.2	V	Anodic peak in DPV vs. Ag/AgCl
Optimal Electrolyte	Phosphate-Buffered Saline (PBS)	pH 7.4; 0.05 M	Physiological conditions
DPV Scan Rate (Optimized)	100	mV/s	Used for calibration
DPV Linear Range	2.5-50	µg/mL	GMB concentration
DPV Limit of Detection (LOD)	0.85	µg/mL	Calculated (S/N = 3)
DPV Sensitivity	0.9137	µA mL/µg	Calibration curve slope
Amperometry Applied Potential	2.0	V	Fixed potential for AMP
AMP Linear Range	0.5-65	µg/mL	GMB concentration (pH 7.4)
AMP Limit of Detection (LOD)	0.15	µg/mL	Calculated (S/N = 3)
AMP Sensitivity (pH 7.4)	0.0741	µA mL/µg	Calibration curve slope
Potential Shift with pH	21.4	mV pH^-1	Observed potential decrease with pH increase
HPLC Mobile Phase	Phosphoric acid 0.1% (v/v)-methanol	97:3 (v/v)	Control method
HPLC Detection Wavelength	272	nm	UV detection

Key Methodologies

Electrode Selection and Preparation:
- The BDDE (3-mm diameter) was selected after testing conventional electrodes (GCE, SPEs, PGE, AuNPs) which failed to detect GMB oxidation below 1.5 V.
- BDDE cleaning involved polishing with 3-µm diamond polish followed by 30 min sonication in ultrapure water.
Electrolyte and pH Optimization:
- GMB oxidation was tested using DPV across Britton Robinson Buffer (BRB) solutions (pH 2-12). Peak current was highest at pH 5.
- Phosphate-Buffered Saline (PBS) at pH 7.4 (0.05 M) was chosen for subsequent studies due to its physiological relevance and good signal intensity.
Voltammetry (DPV) Optimization:
- Cyclic Voltammetry (CV) confirmed the GMB oxidation was irreversible.
- Scan rate studies (5 mV/s to 200 mV/s) showed the process is diffusion-controlled (log(I) vs. log(v) slope of 0.226).
- Optimized DPV parameters: Step potential (0.01 V), Modulation amplitude (0.05 V), Scan rate (100 mV/s).
Amperometry (AMP) Optimization:
- AMP was performed at a fixed potential of 2.0 V to maximize sensitivity while maintaining acceptable baseline noise.
- Measurements involved successive additions of concentrated GMB solution into 5 mL PBS (pH 7.4 or pH 5.5) under continuous stirring, recording the resulting current leaps over time.
Real Sample Analysis and Validation:
- Pharmaceutical formulations (powder and concentrate) were analyzed using the optimized DPV and AMP procedures.
- Results were compared against standard HPLC-UV (mobile phase: 0.1% phosphoric acid/methanol 97:3; detection at 272 nm) and UV-Vis spectrophotometry (270 nm).
- Statistical analysis (ANOVA and Bland-Altman plot) confirmed high accuracy, robustness, and strong correlation between the BDDE methods and the control methods.

Commercial Applications

Pharmaceutical Quality Control (QC): Provides a rapid, low-cost, and robust alternative to HPLC-UV for routine quality assurance of Gemcitabine formulations, particularly in hospital settings where infusion solutions are prepared ex tempore.
Drug Delivery System Analysis: Essential tool for research and development (R&D) focused on novel antitumor drug carriers (liposomes, nanoparticles, dendrimers), enabling fast quantification of drug loading, encapsulation efficiency, and in vitro release kinetics in physiological or tumor media (e.g., PBS pH 5.5).
Electrochemical Sensor Manufacturing: BDDE technology is highly valuable for creating stable, reusable sensors for complex organic molecules due to its large potential window, low background current, and resistance to fouling.
Biomedical Analysis: Potential application in developing point-of-care devices for therapeutic drug monitoring (TDM) of Gemcitabine and other pyrimidine nucleoside drugs in biological fluids, leveraging the method’s speed and simplicity.
High-Accuracy Analytical Validation: The BDDE methods serve as excellent supplementary or replacement tools for conventional physiochemical methods, offering validated accuracy comparable to European Pharmacopoeia standards.

View Original Abstract

The development of fast and easy-to-use methods for gemcitabine detection is of great interest for pharmaceutical formulation control in both research laboratories and hospitals. In this study, we report a simple, fast and direct electrochemical method for gemcitabine detection using a boron-doped diamond electrode. The electrochemical oxidation of gemcitabine on a boron-doped diamond electrode was found to be irreversible in differential pulse voltammetry, and scan rate influence studies demonstrated that the process is diffusion-controlled. The influence of the pH and supporting electrolytes were also tested, and the optimized differential pulse voltammetry method was linear in the range of 2.5-50 μg/mL, with a detection limit of 0.85 μg/mL in phosphate-buffered saline (pH 7.4; 0.1 M). An amperometric method was also optimized for gemcitabine detection. The linear range of the method was 0.5-65 μg/mL in phosphate-buffered saline of pH 7.4 as well as pH 5.5, the limit of detection being 0.15 μg/mL. The optimized differential pulse voltammetry and amperometric detection strategies were successfully applied to pharmaceutical formulations, and the results were compared to those obtained by high-performance liquid chromatography and UV-Vis spectrophotometry with good correlations.

Tech Support

Original Source

DOI: https://doi.org/10.3390/ph14090912

References

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2019 - Tumor-Specific Delivery of Gemcitabine with Activatable Liposomes [Crossref]
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2020 - Cytotoxic Effects of Gemcitabine-Loaded Solid Lipid Nanoparticles in Pancreatic Cancer Cells [Crossref]
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