One of the most common questions in biosensor development is whether to begin with a direct electrochemical measurement or immediately pursue a more sophisticated recognition strategy such as an aptamer or antibody assay. This question frequently arises when developing point-of-care diagnostics for targets such as cytochrome c, an electroactive protein with well-established biological significance.
Start Simple
When a molecule is inherently electroactive, the most practical starting point is often to investigate whether it can be measured directly at an electrode surface. For cytochrome c, direct electrochemical detection offers several advantages:
- Simpler assay architecture
- Lower development complexity
- Faster experimental validation
- Reduced reagent costs
- Easier path towards manufacturability
Rather than immediately investing time and resources into aptamer selection, antibody generation, surface chemistry optimisation, and assay integration, it can be valuable to establish what performance is achievable through direct electrochemical detection alone.
Why Carbon Electrodes Are Worth Investigating
Many researchers naturally gravitate toward gold electrodes because there is a substantial body of literature describing cytochrome c measurements on gold surfaces. However, laboratory success and commercial success are not always driven by the same factors. For point-of-care applications, carbon electrodes often provide a more practical foundation because they are:
- Cost effective
- Scalable to high-volume manufacturing
- Mechanically robust
- Compatible with disposable sensor formats
A suitable starting point for such investigations is the Carbon 501 sensor cartridge: Carbon 501 Sensor Cartridge Pack Whilst gold remains extremely useful in research environments, the continued increase in gold prices can create significant cost pressures when transitioning from proof-of-concept studies to commercial devices. Further discussion on electrode material selection can be found here: Carbon vs Gold vs Platinum Electrodes: Practical Trade-Offs for Real-World Biosensor Development
The Case for Gold
That said, gold electrodes remain highly attractive in certain circumstances. A major reason is the extensive literature describing the formation of self-assembled monolayers (SAMs) on gold surfaces. These SAMs enable convenient immobilisation of biological recognition elements such as:
- Aptamers
- Antibodies
- Peptides
- Other affinity reagents
As a result, many researchers developing highly selective biosensors choose gold as their starting platform. Additional discussion can be found here: Selecting Gold Electrodes for Aptamer-Based Electrochemical Biosensor Development
Measurement Techniques
If direct electrochemical detection is being evaluated, techniques such as square-wave voltammetry can provide a useful starting point. Square-wave voltammetry is widely used because it offers:
- High sensitivity
- Fast measurement times
- Effective discrimination against background currents
- Compatibility with disposable screen-printed electrodes
An introduction to the technique can be found here: Square-Wave Voltammetry, Potentiostats and Screen-Printed Electrodes
Thinking Beyond the Laboratory
A common challenge in biosensor development is the transition from laboratory measurements to real-world deployment. A system intended for commercialisation must eventually address far more than electrochemistry alone, including:
- User experience
- Data handling
- Connectivity
- Reporting
- Regulatory considerations
- Product scalability
For this reason, developers increasingly look for platforms that support both measurement and eventual deployment. The SenseItAll (SIA) platform is designed for this dual role, acting as both a potentiostat and a route towards commercial deployment: SenseItAll Generation 4 Further discussion can be found here: From Measurement to Meaning: Turning Electrochemical Data into Real-World Insight
A Recommended Development Path
For many electroactive targets, the most sensible development pathway is:
- Establish whether direct electrochemical detection is feasible.
- Evaluate performance in relevant biological samples.
- Identify any limitations in sensitivity, selectivity, stability, or robustness.
- Only then consider more complex affinity-based approaches using aptamers or antibodies.
This approach minimises technical risk and allows developers to understand the true analytical challenge before committing to significantly more complicated assay architectures. In many cases, direct detection can provide valuable data surprisingly quickly. Where performance proves insufficient, affinity-based approaches remain available as the next step in the development roadmap.
Conclusion
When developing a point-of-care sensor for cytochrome c or a similar electroactive biomarker, our preference would generally be to start with direct electrochemical detection on a carbon electrode. Carbon provides a practical balance of performance, scalability, manufacturability, and cost. Only once the limitations of direct measurement are understood would we typically move towards more complex strategies involving aptamers, antibodies, or other affinity reagents. By following this staged approach, developers can minimise risk, reduce development costs, and focus resources on the areas that genuinely require additional assay complexity.
