Posts on Jan 1970

Understanding Zeta Potential: Surface Charge at the Solid/Water Interface and Its Role in Modern Materials Science

Explore the importance of zeta potential and surface charge at the solid/liquid interface for biomaterials, membranes, and nanomaterials.

What is Zeta Potential and why does it matter?

Zeta potential is a key physicochemical parameter that describes the electrostatic potential at the slipping plane of a solid surface in a liquid medium. It is not a direct measure of surface charge but rather the potential at the boundary between the stationary layer of fluid attached to the surface and the mobile layer of the surrounding liquid. This parameter is crucial for understanding the behavior of colloidal dispersions, emulsions, and particles in suspension.

The phenomenon of zeta potential emerges from the formation of the electrical double layer (EDL) at the interface between a solid and an aqueous solution. This layer consists of a charged surface and a compensating layer of counter-ions. When an external field is applied, the movement of these ions relative to the surface creates an observable potential difference.

Zeta potential impacts the stability of colloidal systems: high absolute values (positive or negative) indicate strong electrostatic repulsion, which helps prevent aggregation. Conversely, low values may signal a risk of flocculation or sedimentation. Hence, it is a critical metric in formulating stable suspensions in pharmaceuticals, cosmetics, food products, and beyond.

Surface charge at the solid/water interface

The solid/water interface is a dynamic region where charge develops due to several mechanisms: ionization of surface groups, ion adsorption, and lattice defects. The type and density of surface charge depend strongly on pH, ionic strength, and the nature of the surrounding electrolyte.

This surface charge is the origin of the electrical double layer and directly influences interactions with dissolved molecules, proteins, or ions. In biological and environmental systems, it governs key processes such as adsorption, desorption, ion exchange, and membrane transport.

In materials science, understanding surface charge is essential for tailoring materials with desired wettability, adhesion, or biocompatibility. This is especially relevant in applications involving membranes, coatings, and nanostructures that operate in aqueous environments.

How Zeta Potential is measured: techniques and technologies

Several techniques are used to determine zeta potential, including electrophoretic light scattering (ELS) for colloidal systems and streaming potential or streaming current methods for solid surfaces. Among advanced tools, the SurPASS 3 Electrokinetic Analyzer stands out for its ability to directly measure the zeta potential at the solid/liquid interface.

SurPASS 3 uses the classical electrokinetic approach with continuous flow: an electrolyte is passed through a channel formed between the sample surface and a reference, and the resulting flow potential or flow current is measured. This allows for precise, non-destructive analysis of a wide variety of sample geometries, including flat surfaces, powders, fibers, and porous materials.

Moreover, SurPASS 3 integrates automated pH titration using syringe pumps, enabling the determination of the isoelectric point (IEP). This is invaluable for tracking surface modifications and understanding material behavior across different pH levels. This equipment is available in the services of our Unit 16, among other surface characterization techniques.

Key applications across industries

Biomedical and Pharmaceutical

• Implants: Evaluation of surface charge helps optimize biocompatibility and reduce immune rejection.
• Drug delivery: Zeta potential measurements inform the design of nanoparticle carriers to enhance targeting and stability.
• Contact lenses: Assessment of protein adsorption through surface charge analysis supports development of more comfortable and hygienic lenses.

Materials science and engineering

• Membrane characterization: Understanding surface charge assists in improving antifouling properties and selectivity.
• Nanomaterial design: Enables engineering of coatings like graphene oxide with specific interfacial behaviors.
• Coating and adhesion studies: Surface charge insights guide the functionalization and durability of advanced materials.

Environmental and energy applications

• Fuel cell membranes: Characterizing zeta potential supports optimization of ion transport layers.
• Water purification: Adsorbent and filter materials benefit from surface charge tuning for enhanced contaminant removal.

Industrial and commercial uses

• Textile finishing: Zeta analysis supports better dyeing, treatment, and functional coatings.
• Food packaging: Helps in developing antimicrobial or oxygen-barrier films.
• Construction materials: Surface property evaluation leads to more durable and weather-resistant materials.

Competitive edge of SurPASS 3 vs other equipment

Compared to traditional surface analysis equipment, SurPASS 3 offers:

• Automation: Rapid, reproducible results with minimal user intervention.
• Versatility: Accommodates diverse sample shapes and sizes.
• pH-dependent profiling: Automatically determines IEP and adsorption/desorption kinetics.
• Real-time monitoring: Enables observation of surface transformations during chemical treatments.

However, barriers exist:

• Sample requirements: Specific geometries and physical properties are needed.
• Infrastructure needs: Compressed nitrogen supply and optional temperature control increase setup costs.
• Technical expertise: Trained operators are essential for accurate interpretation and maintenance.

Future outlook: emerging and visionary applications

In the near term, SurPASS 3 will continue supporting:

• Real-time adsorption studies for R&D
• Surface engineering of biomaterials
• Environmental material design (e.g., photocatalysts, adsorbents)

Long-term applications include:

• 4D-printed responsive materials with programmed zeta profiles
• Nanomaterials for quantum devices with controlled interfacial properties
• Virus-trapping smart surfaces for healthcare settings
• Carbon capture materials using charge-optimized MOFs

Final thoughts: why Zeta Potential is a foundational metric

Zeta potential is not just a measurement—it’s a gateway to understanding how materials behave at the most fundamental level. From drug delivery to environmental technology, from textile innovation to nanotechnology, the surface charge at the solid/liquid interface defines interactions, stability, and performance.

With tools like the SurPASS 3, researchers and engineers can now explore these properties with unmatched precision and adaptability, paving the way for smarter, more functional materials.

Credits:
Margarita Hierro Oliva
Gabriel Alfranca

What is NANBIOSIS?

The goal of NANBIOSIS is to provide comprehensive and integrated advanced solutions for companies and research institutions in biomedical applications. All of this is done through a single-entry point, involving the design and production of biomaterials, nanomaterials, and their nanoconjugates. This includes their characterization from physical-chemical, functional, toxicological, and biological perspectives (preclinical validation).

In order to access our Cutting-Edge Biomedical Solutions with priority access, enter our Competitive Call here.

NANBIOSIS has worked with pharmaceutical companies of all sizes in the areas of drug delivery, biomaterials and regenerative medicine. Here are a few of them:

Protein Purification Methods: Advanced Techniques and Automation with ÄKTA Pure

Explore modern protein purification methods with a special focus on automated systems like ÄKTA Pure. Learn how advanced chromatography workflows are transforming antibody production, diagnostics, and biotech applications.

What is protein purification and why does it matter?

Protein purification is a fundamental process in biotechnology, biomedical research, and pharmaceutical production. It involves isolating a specific protein of interest from a complex mixture, such as a cell lysate, while preserving its structure and function. This process is critical because the quality, purity, and yield of proteins directly impact downstream applications such as drug development, diagnostic assays, and therapeutic research.

In the context of immunoreagents, such as antibodies, protein purification ensures the removal of host cell proteins, nucleic acids, and other contaminants that may interfere with analytical or clinical performance. High-purity proteins are essential for reproducibility and reliability across scientific studies.

The traditional steps of protein purification

The protein purification workflow typically includes several key steps:

1. Cell lysis and extraction: Disruption of the cell membrane to release intracellular contents using chemical, mechanical, or enzymatic methods.
2. Clarification: Removal of insoluble debris through centrifugation or filtration.
3. Buffer exchange and conditioning: Adjusting pH, salt concentration, and adding stabilizers to optimize protein behavior before chromatography.

Each step requires careful design to avoid loss of protein function or yield.

Overview of core purification techniques

Several chromatographic methods are widely employed:

• Affinity Chromatography: Exploits specific interactions between the protein and a ligand attached to a resin. Protein A or G resins are commonly used for antibody purification.
• Ion Exchange Chromatography (IEX): Separates proteins based on charge differences.
• Size Exclusion Chromatography (SEC): Also known as gel filtration, this method separates proteins based on size and shape.
• Precipitation and Filtration: Less specific methods used in early-stage purification, often resulting in variable quality.

The role of automation in protein purification: ÄKTA Pure

The ÄKTA Pure system represents a shift towards automation in protein purification. Developed by Cytiva, it integrates multiple chromatography techniques into a single, modular, and highly customizable platform.

ÄKTA Pure addresses key challenges in protein purification:

• Reproducibility: Reduces variability associated with manual processes.
• Contamination Control: Automation minimizes exposure and potential degradation.
• Optimization: Through UNICORN software, parameters like flow rate, pH, and gradient elution are finely controlled.

Its use of affinity, ion exchange, and size exclusion chromatography enables highly pure antibody isolation with reduced time and effort.

Comparative analysis: ÄKTA Pure vs other systems

While traditional systems like HPLC offer precision, they lack the flexibility and ease of method development found in ÄKTA Pure. Manual purification methods, although accessible, introduce variability and limit scalability.

Compared to other FPLC systems, ÄKTA Pure stands out due to:

• Integrated software (UNICORN) for intuitive protocol design
• Modular components for flexibility
• Scalability from research to pilot production

Applications and impact in the biomedical and biotech industries

The ÄKTA Pure system has a significant impact in fields requiring consistent, high-purity proteins:

• Diagnostics: Antibody production for ELISA and lateral flow assays
• Biotech R&D: Reliable protein reagents for drug screening and discovery
• Therapeutics: Preparation of immunoreagents for preclinical validation

Barriers to entry and practical considerations

Despite its advantages, implementing ÄKTA Pure may involve high initial equipment cost, training needs for advanced chromatography and software use, and infrastructure adjustments in existing labs.

However, these challenges are offset by long-term gains in quality, throughput, and compliance.

Near and long-term opportunities for automated protein purification

Short and mid-term applications include:

• Routine antibody purification for biomedical research
• Development of high-performance diagnostic reagents
• Protocol refinement to increase yields and consistency

Looking forward:

• Integration with AI for adaptive protocol optimization
• Large-scale purification of advanced antibody formats (e.g., bispecifics, ADCs)
• Continuous processing for industrial-scale immunoreagent production

NANBIOSIS case study: Integrating ÄKTA Pure into CABS services

The CABS platform within NANBIOSIS incorporates ÄKTA Pure to support:

• Rapid adaptation to different antibody types
• Regulatory-compliant workflows
• Expert-guided optimization for diverse client needs

This integration allows seamless transition from research protocols to industrial applications, drastically decreasing the challenges of the technique, and enhancing efficiency and reliability.

Conclusion

Modern protein purification is evolving from manual methods to intelligent, automated systems. ÄKTA Pure exemplifies this shift, offering robust solutions to common challenges in protein production. As the demand for high-quality immunoreagents grows, adopting flexible, scalable purification systems will be key to innovation in diagnostics, therapeutics, and beyond.

Credits:
Nuria Pascual
Gabriel Alfranca

What is NANBIOSIS?

The goal of NANBIOSIS is to provide comprehensive and integrated advanced solutions for companies and research institutions in biomedical applications. All of this is done through a single-entry point, involving the design and production of biomaterials, nanomaterials, and their nanoconjugates. This includes their characterization from physical-chemical, functional, toxicological, and biological perspectives (preclinical validation).

In order to access our Cutting-Edge Biomedical Solutions with priority access, enter our Competitive Call here.

NANBIOSIS has worked with pharmaceutical companies of all sizes in the areas of drug delivery, biomaterials and regenerative medicine. Here are a few of them: