Evaluation of oxidative stress - Nanoparticle-based electrochemical sensors for hydrogen peroxide determination in human semen samples

At a Glance

Metadata	Details
Publication Date	2020-06-02
Journal	Bioelectrochemistry
Authors	Elías Blanco, L. Vázquez, María del Pozo, R. Roy, María Dolores Petit‐Domínguez
Institutions	Universidad Autónoma de Madrid, Instituto de Ciencia de Materiales de Madrid
Citations	15
Analysis	Full AI Review Included

Technical Documentation & Analysis: Diamond Nanoparticle Electrochemical Sensors for Oxidative Stress Evaluation

This document analyzes the research paper “Evaluation of oxidative stress: Nanoparticle-based electrochemical sensors for hydrogen peroxide determination in human semen samples” to provide technical specifications and align the findings with 6CCVD’s advanced MPCVD diamond material catalog.

Executive Summary

This research validates the use of diamond nanoparticles (DNp) as highly effective, enzyme-less electrocatalysts for hydrogen peroxide (H₂O₂) sensing, a critical marker for oxidative stress (OS) related to male infertility.

Core Application: Non-enzymatic electrochemical determination of H₂O₂ in complex biological matrices (human seminal plasma).
Material Validation: Undoped Diamond Nanoparticles (DNp) significantly enhanced the electrochemical signal on both Glassy Carbon (GC) and Gold (Au) substrates.
Superior Sensitivity: The GC/DNp sensor achieved the lowest Limit of Detection (LD) at 1.1 µM, demonstrating superior intrinsic sensitivity compared to all other tested systems, including Au/DNp and GC/CuNp.
Analytical Performance: The GC/CuNp sensor provided the best overall accuracy and recovery in real human semen samples (102% recovery), successfully quantifying H₂O₂ concentration at 1.42 ± 0.05 mM.
Methodology: The sensors utilize a simple, environmentally friendly modification procedure (drop-casting DNp or electrodepositing CuNp) followed by chronoamperometric detection.
6CCVD Value Proposition: This work confirms the potential of diamond nanomaterials in high-sensitivity bioanalytical applications, requiring the high-purity, customizable SCD and PCD substrates that 6CCVD provides for next-generation sensor fabrication.

Technical Specifications

The following table summarizes the key analytical and physical parameters achieved using the nanoparticle-modified electrodes.

Parameter	Value	Unit	Context
Best Limit of Detection (LD)	1.1	µM	Achieved by GC/DNp sensor at +1.0 V
Best Sensitivity (GC/DNp)	42.6	µA/mM	H₂O₂ oxidation at +1.0 V (pH 7)
Best Sensitivity (GC/CuNp)	35.0	µA/mM	H₂O₂ oxidation at +0.2 V (NaOH)
Linear Range (GC/DNp)	3.6 - 340	µM	At optimal potential (+1.0 V)
Linear Range (GC/CuNp)	8.6 - 1000	µM	Widest range achieved
DNp Nominal Size	4 - 15	nm	Supplier specification (SkySpring Nanomaterials)
RMS Surface Roughness (GC/DNp)	73	nm	High roughness due to DNp agglomeration
RMS Surface Roughness (Au/DNp)	15	nm	Smoother morphology on Au substrate
H₂O₂ Concentration (Real Semen)	1.42 ± 0.05	mM	Measured using GC/CuNp sensor
Recovery (Real Semen)	102	%	Average recovery for fortified samples

Key Methodologies

The electrochemical sensors were fabricated using conventional electrode substrates modified with diamond or copper nanoparticles.

Electrode Pre-treatment:
- Glassy Carbon (GC) and Gold (Au) electrodes were polished using 1 µm diamond paste (Buehler).
- Au electrodes were further conditioned by holding potential at +2.0 V (5 s) and -0.35 V (10 s) in 0.1 M H₂SO₄, followed by potential cycling.
DNp Sensor Preparation (GC/DNp and Au/DNp):
- 6 µL of a 1 mg/mL DNp suspension (in water) was drop-cast onto the polished electrode surface.
- The deposit was air-dried and rinsed with water.
CuNp Sensor Preparation (GC/CuNp):
- GC electrodes were immersed in a deaerated solution of 1.8 mM Cu(NO₃)₂ in 0.1 M KNO₃.
- Electrodeposition was performed at -0.4 V (vs Ag/AgCl) for 3 minutes under a nitrogen stream.
- The electrode was then cycled 20 times between -0.60 V and +0.3 V in 0.1 M NaOH solution.
Characterization:
- Atomic Force Microscopy (AFM) was used to characterize surface morphology and nanoparticle aggregation, revealing roughness values ranging from 1.5 nm (GC/CuNp) to 73 nm (GC/DNp).
Electrochemical Measurement:
- Chronoamperometric measurements were performed at optimized potentials (e.g., +1.0 V for GC/DNp, -0.6 V for Au/DNp, +0.2 V for GC/CuNp) in 0.1 M phosphate buffer (pH 7) or 0.1 M NaOH.

6CCVD Solutions & Capabilities

This research highlights the immense potential of diamond nanomaterials in high-performance electrochemical sensing. 6CCVD is uniquely positioned to supply the foundational diamond materials necessary to replicate, optimize, and scale this technology.

Applicable Materials for Sensor Optimization

The DNp sensors demonstrated high sensitivity but suffered from drift and inadequate recovery in complex matrices at high potentials. 6CCVD offers advanced MPCVD diamond materials that can overcome these limitations by providing a stable, conductive, and highly pure substrate platform.

6CCVD Material	Recommendation for H₂O₂ Sensing	Technical Advantage
Boron-Doped Diamond (BDD) Thin Films	Highly Recommended Alternative. Used as the primary electrode material, replacing GC or Au.	Provides the widest electrochemical potential window, superior stability, and low background current, directly addressing the high drift issue observed in the GC/DNp system.
Optical Grade Single Crystal Diamond (SCD)	Recommended for High-Purity Substrates. Used as a base for subsequent DNp or metal nanoparticle deposition.	Ultra-low defect density ensures minimal background noise and maximum material purity for fundamental electrochemical studies. Available in thicknesses from 0.1 µm to 500 µm.
Polycrystalline Diamond (PCD) Wafers	Recommended for Scalability and Large Area Sensors.	Available in large formats (up to 125 mm diameter) for high-throughput sensor array fabrication or industrial scale-up of the GC/DNp concept.

Customization Potential for Advanced Sensor Fabrication

6CCVD’s in-house engineering capabilities directly support the advanced fabrication requirements implied by this research:

Custom Dimensions and Substrates: While the paper used standard GC and Au electrodes, 6CCVD can supply custom-sized BDD or SCD plates/wafers up to 125 mm, optimized for integration into microfluidic or screen-printed electrode architectures.
Precision Polishing: The paper noted that the roughness of the substrate significantly affects DNp aggregation (e.g., Au/DNp roughness was 15 nm). 6CCVD guarantees ultra-smooth surfaces:
- SCD Polishing: Achievable roughness Ra < 1 nm.
- PCD Polishing: Achievable roughness Ra < 5 nm (for inch-size wafers).
- Benefit: Providing substrates with controlled, ultra-low roughness allows researchers to precisely control nanoparticle deposition and morphology, potentially improving sensor reproducibility and stability.
Integrated Metalization: The research utilized Au and CuNp modification. 6CCVD offers internal metalization services (Au, Pt, Pd, Ti, W, Cu) directly onto diamond substrates (SCD or BDD), enabling the creation of integrated, stable, and high-performance hybrid electrodes (e.g., BDD/Ti/Au/DNp).

Engineering Support

6CCVD’s in-house PhD team specializes in the material science of MPCVD diamond and its application in electrochemistry and sensing. We offer consultation services to assist researchers in selecting the optimal diamond material (BDD conductivity level, SCD orientation, surface termination) required to extend this work into robust, commercial-grade Oxidative Stress (OS) Detection platforms.

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

Tech Support

Original Source

DOI: https://doi.org/10.1016/j.bioelechem.2020.107581

References

2012 - Oxidative stress and male infertility-a clinical perspective
2017 - Free radical and superoxide reactivity detection in semen quality assessment: past, present, and future [Crossref]
2017 - Factors and pathways involved in capacitation: how are they regulated? [Crossref]
2018 - Obesity and male infertility: role of fatty acids in the modulation of sperm energetic metabolism [Crossref]
2009 - Oxidative stress and medical antioxidant treatment in male infertility [Crossref]
2017 - Oxidation-reduction potential as a new marker for oxidative stress: correlation to male infertility [Crossref]
2015 - Low concentrations of hydrogen peroxide activate the antioxidant defense system in human sperm cells [Crossref]
2018 - Male infertility: the intracellular bacterial hypothesis [Crossref]
2018 - Caffeine, alcohol, smoking, and reproductive outcomes among couples undergoing assisted reproductive technology treatments [Crossref]
2017 - Systematic review of worldwide trends in assisted reproductive technology 2004-2013 [Crossref]