First Screen-Printed Sensor (Electrochemically Activated Screen-Printed Boron-Doped Diamond Electrode) for Quantitative Determination of Rifampicin by Adsorptive Stripping Voltammetry

At a Glance

Metadata	Details
Publication Date	2021-07-29
Journal	Materials
Authors	Jędrzej Kozak, Katarzyna Tyszczuk‐Rotko, Magdalena Wójciak, Ireneusz Sowa, Marek Rotko
Institutions	Maria Curie-Skłodowska University, Medical University of Lublin
Citations	26
Analysis	Full AI Review Included

Technical Documentation & Analysis: MPCVD Boron-Doped Diamond for Ultra-Trace Voltammetric Sensing

Executive Summary

This technical analysis focuses on the development of an electrochemically activated screen-printed boron-doped diamond electrode (aSPBDDE) for the ultra-sensitive determination of Rifampicin (RIF) using Differential Pulse Adsorptive Stripping Voltammetry (DPAdSV).

Material Focus: The study validates the use of Boron-Doped Diamond (BDD) as a superior working electrode material for high-sensitivity electrochemical sensing.
Ultra-Trace Sensitivity: Achieved exceptionally low detection limits (LOD) of 0.22 pM and quantification limits (LOQ) of 0.73 pM for RIF, significantly surpassing traditional HPLC and spectrophotometric methods.
Activation Mechanism: Electrochemical activation via Cyclic Voltammetry (CV) in 0.1 M NaOH was critical, reducing the charge transfer resistance (Rct) from 286.5 Ω cm² to 105.4 Ω cm².
Surface Optimization: Activation enhanced the surface morphology, increasing roughness (Ra) from 0.451 µm to 0.517 µm, which facilitated RIF adsorption and oxidation.
Robustness and Selectivity: The aSPBDDE demonstrated excellent repeatability (RSD 2.5%) and high selectivity, successfully analyzing RIF in complex matrices like river water and certified bovine urine reference material.
Application: Confirms the viability of screen-printed BDD sensors for fast, simple, and cost-effective in situ analysis of pharmaceuticals in biological fluids and environmental samples.

Technical Specifications

Parameter	Value	Unit	Context
Limit of Detection (LOD)	0.22	pM	RIF determination (DPAdSV)
Limit of Quantification (LOQ)	0.73	pM	RIF determination (DPAdSV)
Unactivated Rct	286.5	Ω cm²	SPBDDE (Electrochemical Impedance Spectroscopy)
Activated Rct	105.4	Ω cm²	aSPBDDE (Electrochemical Impedance Spectroscopy)
Activation Solution	0.1	M	NaOH
Activation Cycles	5	Cycles	Cyclic Voltammetry (CV)
Activation Scan Rate	100	mV s^-1	CV sweep rate
Optimal Accumulation Potential (Eacc)	-0.45	V	DPAdSV optimization
Optimal Accumulation Time (tacc)	120	s	Selected for optimal signal vs. analysis time
Optimal Electrolyte pH	3.0 ± 0.1	N/A	0.1 M Phosphate Buffer Saline (PBS)
Unactivated Roughness (Ra)	0.451	µm	Optical Profilometry (SPBDDE)
Activated Roughness (Ra)	0.517	µm	Optical Profilometry (aSPBDDE)
Repeatability (RSD)	2.5	%	0.1 nM RIF (n=10)

Key Methodologies

The high performance of the sensor was achieved through precise electrochemical activation and optimization of the DPAdSV parameters.

Electrode Substrate: Commercial screen-printed sensors were used, featuring a Boron-Doped Diamond (BDD) working electrode, a carbon auxiliary electrode, and a silver pseudo-reference electrode.
Electrochemical Activation: The SPBDDE was subjected to electrochemical activation using Cyclic Voltammetry (CV).
- Solution: 0.1 M NaOH.
- Parameters: Five voltammetric cycles were applied between 0 and 2 V at a scan rate of 100 mV s^-1.
Electrolyte Selection: The optimal supporting electrolyte was determined to be 0.1 mol L^-1 Phosphate Buffer Saline (PBS) at a pH of 3.0 ± 0.1.
DPAdSV Optimization: Differential Pulse Adsorptive Stripping Voltammetry was performed under the following optimized conditions for RIF determination:
- Accumulation Potential (Eacc): -0.45 V.
- Accumulation Time (tacc): 120 s.
- Amplitude (ΔΕA): 150 mV.
- Scan Rate (v): 100 mV s^-1.
- Modulation Time (tm): 5 ms.
Characterization: Surface changes were confirmed using Scanning Electron Microscopy (SEM) and Optical Profilometry, showing increased porosity and roughness post-activation.
Validation: Real-sample analysis was conducted on river water and bovine urine, with results cross-validated against High-Performance Liquid Chromatography (HPLC/PDA).

6CCVD Solutions & Capabilities

The research successfully demonstrates the critical role of high-quality Boron-Doped Diamond in achieving ultra-low detection limits for pharmaceutical analysis. 6CCVD is uniquely positioned to supply and enhance the BDD materials required to replicate or advance this technology, moving from commercial screen-printed sensors to robust, custom-engineered MPCVD diamond chips.

Applicable Materials

The core requirement for this application is a highly conductive, stable BDD film. 6CCVD provides materials engineered specifically for electrochemical sensing:

Heavy Boron-Doped PCD (Polycrystalline Diamond): Ideal for large-scale production of robust sensors. We offer wafers up to 125mm in diameter and thicknesses from 0.1 µm to 500 µm, ensuring low resistivity and a wide potential window necessary for stripping voltammetry.
BDD Thin Films on Silicon: For researchers requiring integration into existing semiconductor or microelectromechanical systems (MEMS) platforms, 6CCVD supplies BDD films on silicon substrates, allowing for precise lithographic patterning of the electrode array.

Customization Potential

6CCVD’s in-house manufacturing capabilities directly address the material and fabrication needs highlighted by this study:

Research Requirement	6CCVD Custom Solution	Technical Advantage
Low Rct & High Activity	Custom Boron Doping Levels	Precise control over boron concentration during MPCVD growth to guarantee metallic conductivity and maximize electrochemical activity, optimizing the material before activation.
Surface Morphology (Ra)	Polishing & Surface Termination	We offer as-grown surfaces (suitable for activation/porosity) or highly polished surfaces (Ra < 5nm for PCD) for baseline control, allowing researchers to precisely tune the initial surface state for optimal RIF adsorption.
Integrated Electrodes	Custom Metalization Services	We can deposit Au, Pt, Ti, or other metals directly onto the diamond substrate to create integrated, robust three-electrode systems (working, auxiliary, reference) on a single chip, eliminating the need for separate screen-printed components.
Sensor Geometry	Precision Laser Cutting	Custom shaping and sizing of BDD wafers to fit specific microfluidic channels or portable sensor housing designs, ensuring seamless integration into final devices.
Substrate Thickness	Custom Substrates up to 10mm	Providing thick, mechanically stable BDD substrates for high-pressure or harsh environment applications, extending the sensor’s operational lifetime.

Engineering Support

The success of the aSPBDDE relies on the precise interaction between the RIF molecule and the activated diamond surface. 6CCVD’s dedicated team of PhD material scientists offers specialized support:

Material Selection Consultation: Assistance in selecting the optimal diamond type (PCD vs. SCD) and boron doping level to maximize the electrogeneration of hydroxyl radicals and minimize fouling for Ultra-Trace Voltammetric Sensing.
Process Optimization: Guidance on pre-treatment and activation protocols, ensuring the delivered BDD material responds optimally to the electrochemical activation steps (e.g., CV in NaOH) described in this research.
Global Logistics: We ensure reliable, global delivery of custom diamond materials (DDU default, DDP available) to keep your research timeline on track.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

In this paper, a screen-printed boron-doped electrode (aSPBDDE) was subjected to electrochemical activation by cyclic voltammetry (CV) in 0.1 M NaOH and the response to rifampicin (RIF) oxidation was used as a testing probe. Changes in surface morphology and electrochemical behaviour of RIF before and after the electrochemical activation of SPBDDE were studied by scanning electron microscopy (SEM), CV and electrochemical impedance spectroscopy (EIS). The increase in number and size of pores in the modifier layer and reduction of charge transfer residence were likely responsible for electrochemical improvement of the analytical signal from RIF at the SPBDDE. Quantitative analysis of RIF by using differential pulse adsorptive stripping voltammetry in 0.1 mol L−1 solution of PBS of pH 3.0 ± 0.1 at the aSPBDDE was carried out. Using optimized conditions (Eacc of −0.45 V, tacc of 120 s, ΔEA of 150 mV, ν of 100 mV s−1 and tm of 5 ms), the RIF peak current increased linearly with the concentration in the four ranges: 0.002-0.02, 0.02-0.2, 0.2-2.0, and 2.0-20.0 nM. The limits of detection and quantification were calculated at 0.22 and 0.73 pM. The aSPBDDE showed satisfactory repeatability, reproducibility, and selectivity towards potential interferences. The applicability of the aSPBDDE for control analysis of RIF was demonstrated using river water samples and certified reference material of bovine urine.

Tech Support

Original Source

DOI: https://doi.org/10.3390/ma14154231

References

2017 - Simultaneous determination of isoniazid and rifampicin by UV spectrophotometry
2015 - Development of a sensitive and rapid method for rifampicin impurity analysis using supercritical fluid chromatography [Crossref]
2019 - A validated stable HPLC method for the simultaneous determination of rifampicin and 25-O-desacetyl rifampicin—evaluation of in vitro metabolism [Crossref]
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2019 - Fast and simple LC-MS/MS method for rifampicin quantification in human plasma
2017 - Determination of protein-unbound, active rifampicin in serum by ultrafiltration and ultra performance liquid chromatography with UV detection. A method suitable for standard and high doses of rifampicin [Crossref]
2021 - Determination of rifampin concentrations by urine colorimetry and mobile phone readout for personalized dosing in tuberculosis treatment [Crossref]
2005 - Optimization of a cyclodextrin-based sensor for rifampicin monitoring [Crossref]