Nanopore Protein Sequencing: Principles, Current Progress, and Research Applications

Nanopore protein sequencing is an emerging technique in next-generation proteomics, offering the potential for single-molecule protein readout, which could complement existing peptide-centric workflows.

It is also easy to misunderstand. Significant progress has been made in amino acid/peptide discrimination, motor-controlled translocation, and signal modeling, although the field continues to address key technical barriers. As a recent perspective in Trends in Biochemical Sciences stresses, true de novo protein sequencing with nanopores remains an open challenge rather than a solved routine method (Rukes et al., 2025).

Key takeaways

• This approach aims to infer protein identity or sequence-related patterns by reading electrical signals produced when a protein or peptide interacts with a nanoscale pore.
• Compared with DNA/RNA nanopore sequencing, proteins add a larger "alphabet," folding/unfolding physics, and diverse post-translational modifications (PTMs), which complicate both signal acquisition and decoding.
• Near-term research value often lies in controlled peptide readouts, protein fingerprinting, and modification/variant-sensitive signals—alongside orthogonal validation (commonly with MS-based methods).

Introduction: What Is Protein Nanopore Sequencing?

Definition and Core Concept

Protein nanopore sequencing can be defined as a single-molecule protein analysis approach in which proteins, peptides, or amino acid–containing analytes are interrogated by a nanopore sensor and translated into electrical (typically ionic-current) signals. Those signals are then analyzed to infer molecular identity, sequence-related patterns, or modification-associated changes.

At the most intuitive level, the nanopore behaves like a nanometer-scale "bottleneck" in an ionic circuit. When a peptide enters, dwells in, or translocates through the sensing region, it perturbs the current in a way that reflects its physical chemistry—size, charge distribution, and local interactions with the pore environment. A tutorial review on nanopore protein sensing emphasizes that even for "simple" protein events, multiple interaction modes can appear (e.g., collision, partial entry, adsorption, tumbling), which is part of what makes interpretation non-trivial (Varongchayakul et al., 2018).

The relationship to DNA/RNA nanopore sequencing is best understood as shared sensing physics, different decoding difficulty:

• Similar sensing concept. Both measure changes in ionic current (or related signals) as a biopolymer interacts with a nanometer-scale pore under an applied potential.
• Greater complexity for proteins. Proteins introduce 20 canonical amino acids (and many PTMs), broad conformational diversity, and analyte-dependent charge states—making it harder to "ratchet" and decode with base-like regularity.

Why This Technology Is Emerging

Renewed interest in nanopore-based protein analysis reflects a demand for next-generation sequencing strategies capable of capturing protein heterogeneity, which current methods cannot fully address.

Three key drivers are commonly discussed in the literature and research:

First, the proteome is not a static catalog of gene products. A single gene can give rise to multiple proteoforms through alternative splicing, sequence variants, proteolysis, and a spectrum of PTMs. In many projects, the question is not "what protein family is present?" but "which proteoform(s) dominate, and what modifications coexist on the same molecule?"

Second, classic sequencing approaches are powerful but not universally sufficient. Edman degradation remains highly valuable for N-terminal sequencing in purified contexts, and LC-MS/MS is the workhorse for identification, quantification, and PTM analysis. Yet neither is automatically a direct, end-to-end, single-molecule readout of an intact proteoform in all settings.

Third, there is sustained interest in direct or near-direct readout for low-input or otherwise difficult samples, where a single-molecule approach could be attractive if (and this is the key caveat) controlled translocation and reliable decoding can be achieved.

For teams exploring feasibility or complementary workflows, Creative Proteomics' Nanopore Protein Sequencing service provides a practical entry point into how nanopore-based concepts can be positioned alongside other sequencing approaches, without assuming the technology is already a routine replacement.

How Nanopore Protein Sequencing Works

Core Working Principle

A nanopore sensor, whether biological, solid-state, or hybrid, is integrated into a membrane or sensing platform that separates two electrolyte compartments. When a voltage bias is applied across the membrane, ions flow through the pore and create a baseline "open pore" current.

When a protein or peptide approaches and interacts with the sensing region, it partially excludes ions and/or perturbs the local electrostatics. The result is a change in current amplitude, dwell time, and often a richer pattern of sublevels. In the tutorial framework described by Varongchayakul and colleagues, these event features are the basic observables for single-molecule nanopore protein analysis (Varongchayakul et al., 2018).

Crucially, the signal is not a simple one-to-one "amino acid letter" readout in most current implementations. Instead, researchers often aim to extract sequence-related patterns or modification-sensitive features from:

• the magnitude of current blockade,
• the time spent in the sensing region,
• the presence of repeatable sublevels,
• and the response under controlled assay conditions.

Typical Workflow

In practice, nanopore protein sequencing research is best thought of as a pipeline from molecular handling to signal inference. Depending on the platform and the experimental question, steps can include unfolding, digestion to peptides, tagging, conjugation to carriers, and controlled translocation.

The table below summarizes a typical workflow and why each step matters.

Main Nanopore Platform Types

The field commonly describes three platform families. Each comes with different "degrees of freedom" for pore engineering and for controlling how proteins behave near the sensing region.

Biological nanopores are protein-based channels (often engineered) with defined structures and engineerable sensing regions. Because the pore is itself a biomolecule, it can sometimes be tuned (by mutation or chemical functionalization) to enhance sensitivity to specific analyte features. A comprehensive review in ACS Nano summarizes how engineering biological nanopores, carrier strategies, and data-driven decoding are being combined in the push toward protein sequencing (Wei et al., 2023).

Solid-state nanopores are synthetic apertures fabricated in materials such as silicon nitride or emerging 2D materials. They offer robustness and tunable geometry, and they are attractive for integration with electronics and arrays. For protein work, the central challenge is often achieving sufficiently precise sensing regions and stable surface chemistries that support discriminating signals.

Hybrid systems combine elements from both worlds—for example, integrating biological nanopores into solid-state supports, or combining engineered recognition elements with nanopore readout. The rationale is straightforward: use biological specificity where it helps, and solid-state stability where it helps. In practice, hybrid designs can also introduce new sources of noise and sealing challenges, so their performance is highly implementation-dependent.

Why Protein Sequencing Is More Challenging Than DNA Sequencing

Molecular Complexity of Proteins

It is tempting to assume that if DNA nanopore sequencing is mature, proteins should be "next." But proteins are fundamentally a harder object to decode.

The first reason is the alphabet: proteins have 20 canonical amino acids rather than four nucleic acid bases, and those residues vary widely in size, charge, hydrophobicity, and side-chain chemistry.

The second reason is structural heterogeneity. A DNA strand is typically handled as a relatively uniform polymer; proteins, in contrast, occupy a landscape of folded domains, flexible regions, disulfide constraints, transient conformations, and heterogeneous charge states. Even in denaturing conditions, polypeptides can adopt multiple conformations.

The third reason is chemical diversity beyond sequence. PTMs (phosphorylation, acetylation, glycosylation, and more), sequence variants, and proteolytic processing create a distribution of proteoforms. For nanopore signals, these changes can be both an opportunity (a measurable perturbation) and a confounder (overlapping patterns).

Technical Barriers in Nanopore-Based Protein Analysis

The technical bottlenecks are often less about "detecting a protein" and more about controlling and interpreting the interaction well enough to extract sequence-level information.

Several recurring barriers include:

• Controlling motion through the pore. Protein translocation can be too fast for readable signals, or it can be dominated by sticking/adsorption events.
• Protein translocation control and slowing translocation are harder because proteins lack a uniform charged backbone like nucleic acids and can present diverse charge distributions.
• Unfolding vs informativeness. You may need to unfold structured proteins for linear readout, but unfolding conditions can also erase meaningful structural cues or introduce unwanted interactions.
• Amino-acid signal overlap. Many residues have similar physical properties, so "amino acid discrimination in nanopores" can require exceptionally stable sensing regions and high-quality modeling.
• Noise and mixed interaction modes. Practical nanopore traces reflect not only the analyte but also bandwidth/noise, pore drift, and multiple event types.

A useful way to communicate the gap is to compare DNA and protein nanopore work in terms that matter to experimentalists.

Current Progress in Nanopore Protein Sequencing

Amino Acid and Peptide Discrimination

Nanopore-based protein analysis has seen the most progress in amino acid and short peptide analysis, where experimental control is more manageable.

The 2023 ACS Nano review by Wei and colleagues catalogs multiple strategies—engineered biological pores, chemical derivatization, carrier peptides, and optimized environments—aimed at differentiating residues and small peptide motifs (Wei et al., 2023). Across these approaches, the same themes recur: increase signal resolution, slow the analyte in the sensing region, and use modeling or machine learning to map noisy signals onto molecular states.

Protein Fingerprinting and Identification

A second track of progress is protein fingerprinting: using characteristic signal patterns for protein or peptide identification without requiring full de novo, residue-by-residue reconstruction.

For many labs, this is not a compromise—it is a pragmatic near-term use case. If a method can reliably distinguish a targeted set of proteins, detect engineered substitutions, or track purified-protein identity shifts across conditions, it can be scientifically valuable even before complete sequencing is routine.

This framing also aligns with how recent reviews position the field: nanopores are advancing toward protein identification and sequencing, but the full de novo endpoint remains a frontier challenge (Rukes et al., 2025).

PTMs, Variants, and Proteoform-Related Signals

Many researchers are interested in nanopore approaches precisely because proteoforms matter. In principle, PTMs and substitutions can alter nanopore signals by changing local sterics, charge distribution, and interaction kinetics.

The important nuance is what is being read: a nanopore trace usually reflects a local window in or near the sensing region rather than a perfectly isolated single residue. That means nanopore detection of PTMs may be feasible in controlled contexts (e.g., defined peptides, engineered carriers, repeated reads) but is still being actively developed for more complex mixtures.

A particularly instructive example of "control + rereading" comes from work demonstrating multi-pass, single-molecule reading of long protein strands using a motor/unfoldase concept. In this approach, a ClpX unfoldase ratchets a protein through a CsgG nanopore and enables rereading to improve decoding fidelity (Motone et al., 2023). For PIs following the space, this line of work is valuable not because it proves routine proteome-wide sequencing, but because it demonstrates plausible physical strategies for controlling long polypeptide motion and extracting repeatable signals.

Key Takeaway: For publication-grade claims, treat PTM/variant-sensitive nanopore signals as hypothesis-generating until they are supported by orthogonal evidence.

Technology Maturity and Practical Positioning

Nanopore protein sequencing is promising, but it is still developing as a general-purpose sequencing modality. It should not be positioned as a routine replacement for LC-MS/MS, Edman degradation, or top-down proteomics.

A more realistic framing for research planning is:

• nanopore methods can add value in exploratory studies,
• targeted feasibility assessments,
• and integrated characterization workflows where orthogonal validation is expected.

Research Applications

Next-Generation Proteomics

The long-term promise is clear: if single-molecule protein readout becomes robust, it could enable new classes of proteomics experiments where low input, directness, or molecule-by-molecule heterogeneity are essential.

Near-term, nanopore-based protein analysis can serve as a complementary signal source—especially in research settings where purified proteins or defined peptide systems are available and where the goal is to test whether a nanopore readout can distinguish relevant molecular states.

For broader proteomics needs today, many research programs evaluate nanopore ideas alongside established pipelines. In that context, Creative Proteomics' Proteomics Analysis Services can be a useful companion resource when designing an integrated, multi-method approach.

Proteoform and Full-Length Protein Research

Proteoforms—distinct molecular forms of a protein arising from sequence variation, processing, and PTM combinations—often motivate interest in long-read protein strategies.

Even when full de novo readout is not achieved, approaches that improve controlled long-polypeptide interrogation can inform how intact proteins behave under force, how domains unfold, and how specific sequence edits shift the signal. For PI-led labs, these measurements can be valuable as mechanistic evidence when combined with orthogonal methods.

PTM and Variant Research

Variant-sensitive and modification-sensitive signals are one of the most compelling potential advantages of nanopore methods. Because the signal originates from physical chemistry in a confined sensor, PTMs that alter charge or steric profile can plausibly shift event features in measurable ways.

The practical research question is often not "can a nanopore see PTMs?" but "under what constraints can it see my PTM or substitution reproducibly, and how do we validate the inference?" This is where complementary LC-MS/MS or top-down proteomics remains central, both for discovery and for confirmation.

Low-Input, Precious, or Engineered Samples

Single-molecule measurement is attractive when samples are limited, precious, or engineered in ways that make standard workflows difficult.

In practice, nanopore feasibility can depend on sample purity, buffer compatibility, and the ability to control capture and translocation. That often makes purified proteins, engineered constructs, antibody-related samples, and defined modified peptides reasonable candidates for exploratory nanopore evaluation—while complex mixtures can be substantially harder.

Comparison with Established Protein Sequencing Methods

Nanopore Protein Sequencing vs Mass Spectrometry

Nanopore protein sequencing is fundamentally an electrical, single-molecule readout. When it works well, its appeal is the possibility of direct or near-direct sensing of sequence-related features in real time—an idea often discussed under the umbrella of single-molecule protein sequencing.

Mass spectrometry, by contrast, is a mature ecosystem for protein identification, quantification, and PTM analysis. It is exceptionally strong for routine proteomics and for robust workflows backed by decades of method development. In many studies, MS relies on peptide fragmentation and database matching; for sequence inference and modification mapping, the interpretation is powerful but can be indirect when the aim is intact proteoform resolution.

From a method-selection perspective, it is more helpful to treat nanopore as a potential complement—especially in early-stage feasibility studies—rather than a replacement.

Nanopore Protein Sequencing vs Edman Degradation

Edman degradation remains a gold standard for N-terminal sequencing when sample purity and N-terminus accessibility allow it. Its value is clarity: direct chemistry at the N-terminus with interpretable outputs.

Nanopore protein sequencing is an exploratory next-generation strategy with a different ambition: potentially moving beyond an N-terminal-only readout and enabling long-range interrogation under controlled translocation. However, its current constraints mean it is most credible as a research method under development rather than a universal "better Edman."

Nanopore Protein Sequencing vs Top-Down Proteomics

Top-down proteomics is an established route for intact proteoform characterization by MS, with strong relevance to PTM and proteoform analysis when instrumentation and expertise are available.

Nanopore approaches, if they mature, could offer a different kind of long-read advantage at the single-molecule level. The key phrase is "if they mature": robust complete sequence interpretation from nanopore signals is still being actively researched.

Method Selection Considerations

Because each approach measures something slightly different, method selection is usually about what you need to conclude and how confident you need to be.

A practical way to frame the choice is to ask:

• What is the sample type and purity?
• What is the relevant molecular scale: intact protein, long peptide, or peptide fragments?
• What is the required readout: identification only, sequence-level evidence, PTM mapping, variant detection, or proteoform-level insight?
• Is this exploratory (hypothesis generation) or routine (high-confidence reporting)?
• Is sample amount limiting?
• What orthogonal validation will be needed?

Sample and Project Considerations

Sample Types That May Be Considered

Nanopore feasibility is highly sample-dependent. In general, exploratory studies tend to be most tractable when you can control the molecular system and reduce competing signals.

Common sample categories considered in nanopore protein sequencing research include purified proteins, peptides or fragments, engineered proteins, modified proteins/peptides, and low-abundance or precious samples.

Key Information for Feasibility Evaluation

For a feasibility evaluation, the most useful information is the minimum set that determines whether controlled nanopore interaction is plausible and what kind of inference is realistic.

When Nanopore Protein Sequencing May Be Worth Exploring

Nanopore approaches may be worth exploring when conventional methods provide incomplete answers, when single-molecule heterogeneity is central, when proteoform/PTM/variant heterogeneity is the primary scientific question, or when sample amount is limited.

Just as importantly, nanopore exploration is most productive when it is planned as part of an integrated strategy: define what the nanopore readout would add, what it would not settle, and what orthogonal methods will provide confirmation.

How Creative Proteomics Supports Nanopore Protein Sequencing Research

Research-Oriented Project Evaluation

A research-oriented evaluation starts with your sample and your scientific question—not with a one-size-fits-all workflow. For nanopore-related projects, feasibility often depends on whether the measurement goal is best framed as controlled peptide sensing, protein fingerprinting, or a long-read exploratory study.

When nanopore approaches are not the best fit, a realistic plan is to combine methods. For broader sequencing needs, Creative Proteomics' Protein Sequencing Service page outlines complementary sequencing capabilities that can be paired with nanopore exploration under a coherent study design.

Integrated Protein Sequencing Capabilities

Frontier nanopore work is typically strongest when it is integrated with established characterization methods and bioinformatics interpretation.

Creative Proteomics supports research workflows that can include nanopore-based protein sequencing exploration alongside mass spectrometry-based protein sequencing, de novo sequencing strategies, top-down proteomics, PTM analysis, and proteomics bioinformatics—selected based on project goals and evidence requirements.

Bioinformatics and Data Interpretation Support

Signal interpretation is a core limiter in nanopore work: it is rarely the pore alone that solves the problem.

Because nanopore events can reflect multiple interaction modes and because amino-acid signatures can overlap, computational analysis (feature extraction, modeling, classification, and cross-platform validation) becomes central. For teams building an integrated analysis plan, Creative Proteomics' Bioinformatics Services page is a natural next step for understanding how signal-level analysis can be paired with MS-based interpretation.

Next step (research-focused): If you’re considering nanopore readouts for a specific protein/peptide system, a short feasibility discussion can help align the measurement goal (fingerprinting vs variant/PTM sensitivity vs long-read exploration) with an appropriate orthogonal validation plan.

FAQs

What is nanopore protein sequencing, in one sentence?

Nanopore protein sequencing is a single-molecule approach that infers protein identity or sequence-related features by measuring how a protein or peptide changes the electrical signal (usually ionic current) as it interacts with a nanopore.

How does nanopore protein sequencing work at the signal level?

A voltage drives ions through a nanopore to create a baseline current, and a peptide's presence in the sensing region perturbs that current, producing event features such as blockade depth, dwell time, and sublevels; those features are then modeled to map signals to molecular states (Varongchayakul et al., 2018).

Is nanopore protein sequencing the same as DNA nanopore sequencing?

No. The sensing concept is similar, but proteins add a larger alphabet, folding/unfolding physics, and diverse PTMs, making both translocation control and decoding substantially more complex than in nucleic acids.

What are biological vs solid-state nanopores for proteins?

Biological nanopores are protein channels that can be engineered at the amino-acid level to tune sensing interactions, while solid-state nanopores are fabricated apertures in inorganic materials with tunable geometry and robustness; hybrid designs aim to combine biological specificity with solid-state stability, but each platform brings distinct noise, surface-interaction, and control trade-offs.

Can nanopore methods detect PTMs like phosphorylation or glycosylation?

Potentially, yes—PTMs can change local sterics and charge and therefore shift nanopore signals—but feasibility depends on controlled experimental context (e.g., defined peptides or engineered constructs) and on having an analysis model that can separate PTM effects from other sources of signal variation.

What are the biggest technical bottlenecks today?

The most persistent bottlenecks are controlling peptide/protein motion through the pore (so events are slow and repeatable enough to read) and building decoding models that can distinguish similar residues and modifications without being confused by noise and mixed interaction modes.

What does "protein fingerprinting with nanopores" mean?

Protein fingerprinting refers to identifying a protein (or distinguishing variants/modified forms) using characteristic signal patterns rather than reconstructing a complete de novo sequence; it can be a pragmatic near-term goal while full sequencing remains a frontier challenge.

What sample types are most suitable for early feasibility studies?

Purified proteins, defined peptides/fragments, engineered constructs, and known modified peptides are often more tractable starting points because they reduce competing signals and enable clearer validation against orthogonal methods.

How should results be validated for publication-grade rigor?

Treat nanopore readouts as one evidence stream: pair them with orthogonal confirmation (commonly LC-MS/MS and, where appropriate, top-down proteomics) and report the experimental controls that rule out nonspecific adsorption, mixed event modes, and model overfitting.

Can nanopore protein sequencing replace mass spectrometry?

Not as a routine replacement today. Mass spectrometry remains the most mature and broadly applicable platform for proteomics and PTM analysis, while nanopore protein sequencing is still developing and is most credibly positioned as complementary for specific research questions.

Is de novo protein sequencing with nanopores solved?

No—reviews in the field describe true de novo nanopore protein sequencing as an open challenge, even as protein identification and controlled-readout strategies continue to advance.

References

1. Advancing nanopore technology toward protein identification and sequencing
2. Engineering Biological Nanopore Approaches toward Protein Sequencing
3. Single-molecule protein sensing in a nanopore: a tutorial
4. Multi-pass, single-molecule nanopore reading of long protein strands with single-amino-acid sensitivity

For research use only, not intended for any clinical use.