Rapid, Label-Free Aggregation Detection & Colloidal Stability Assessment — From 2 µL of Sample in Under a Minute
Creative Proteomics provides dynamic light scattering (DLS) services for rapid, label-free screening of protein size, polydispersity, aggregation, and colloidal stability. Our high-throughput plate-based platform — using 96/384/1536-well formats — measures hydrodynamic radius (Rh), polydispersity index (PDI), thermal aggregation onset (Tonset/Tagg), and diffusion interaction parameters (kD, B22) from as little as 2 µL of sample in under one minute per measurement. This makes DLS the highest-throughput technique available for early candidate triage, formulation screening, and batch-to-batch comparability in biopharmaceutical development.
DLS occupies a unique position in the analytical toolkit because it detects the earliest signs of aggregation and self-association — trace oligomers and reversible aggregates that SEC may miss due to dilution or column interaction. A PDI below 0.1 indicates a monodisperse, well-behaved sample; a PDI above 0.3 flags aggregation risk that demands formulation optimization or candidate deselection. This binary readout — combined with sub-µL sample consumption and
Core Capabilities:
Dynamic light scattering (DLS) measures the Brownian motion of particles in solution by analyzing time-dependent fluctuations in scattered laser light. Larger particles diffuse more slowly, producing slower intensity fluctuations; smaller particles diffuse faster. A digital autocorrelator converts these fluctuation patterns into a diffusion coefficient, from which the hydrodynamic radius (Rh) is calculated via the Stokes-Einstein equation. The width of the size distribution — the polydispersity index (PDI) — reports on sample homogeneity: PDI 0.3 indicates significant size heterogeneity or aggregation.
DLS is a screening and triage tool, not a high-resolution structural technique. Its value lies in speed and sensitivity to trace aggregates: a single measurement answers the most fundamental developability question — is my protein monodisperse and aggregation-free under these conditions? For formulation screening, DLS tests dozens of buffer/pH/excipient combinations in hours rather than days. This screening-first workflow — DLS for rapid triage, SEC-MALS or AUC for confirmatory characterization — reflects current best practice in biopharmaceutical developability (Forder, University of Delaware, 2024).
If your protein therapeutic development program needs rapid, quantitative answers about aggregation risk, colloidal stability, or formulation behavior — DLS provides the data in minutes, from microliters of sample.
Detects Trace Aggregates at
DLS intensity distributions are weighted by the sixth power of particle radius — a 1% population of 100 nm aggregates contributes ~10⁶× more scattering intensity than 1 nm monomers. This inherent bias toward large species makes DLS extraordinarily sensitive to trace oligomers and pre-aggregate species that SEC may miss entirely due to column dilution, filtration, or matrix interaction. For developability screening — where catching aggregation-prone candidates early saves millions in downstream development costs — this sensitivity is the technique's most valuable attribute — catching aggregation-prone candidates early, when formulation changes are still inexpensive.
kD and B22 — Predict Long-Term Stability from Dilute Solution Measurements
The diffusion interaction parameter (kD) and second virial coefficient (B22) — measured by DLS at multiple protein concentrations — quantify net protein–protein interactions in solution. Negative kD values indicate net attractive interactions (aggregation-prone); positive kD values indicate net repulsive interactions (colloidally stable). A 2024 dissertation (Forder, University of Delaware) demonstrated that kD measured by DLS predicts high-concentration behavior — including viscosity, phase separation, and long-term storage stability — from measurements at
96 Conditions in Under 2 Hours
Plate-based DLS on 96/384/1536-well formats — with automated acquisition and analysis — screens a full formulation matrix (pH × ionic strength × excipient type × excipient concentration) in a single experiment. Each well consumes 2–4 µL of sample and takes 1 hour per condition) or AUC (>3 hours per condition) is decisive during early development when dozens of candidates and conditions must be evaluated simultaneously.
Thermal Ramp Stability from a Single Sample Aliquot
Temperature-controlled DLS (4–85°C) tracks Rh and scattering intensity as a function of temperature — identifying Tonset (first detectable aggregation), Tagg (aggregation midpoint), and Tsize (particle size transition temperature) from a single 20 µL sample. These parameters define the safe handling window for manufacturing (hold steps, viral inactivation, UF/DF) and storage. Combined with isothermal stability at user-specified temperatures, the data directly support formulation selection and process development.
Five assay configurations span the full developability workflow — from rapid first-pass candidate triage through detailed colloidal stability profiling for late-stage formulation development.
DLS is a screening tool — not a high-resolution characterization technique. Pair it with orthogonal methods for complete developability assessment.
| Feature | DLS | SEC-MALS | SV-AUC | nanoDSF |
| What It Measures | Hydrodynamic radius, PDI, aggregation | Absolute MW + size (SEC separation) | Sedimentation coefficient, MW, shape | Thermal unfolding (Tm, Tonset) |
| Detects Trace Aggregates | Yes — very sensitive ( | Yes — but dilution may dissociate reversible aggregates | Yes — gold standard for aggregate quantification | No — detects unfolding, not aggregation directly |
| Measures Colloidal Stability (kD/B22) | Yes — concentration-dependent DLS | No | No | No |
| Speed per Sample | 15–30 minutes | 3–8 hours | ~1 hour (thermal ramp) | |
| Sample Required | 2–20 µL at 0.1–10 mg/mL | 50–100 µL at 0.5–5 mg/mL | 400 µL at 0.5–1 mg/mL | 10 µL at 0.1–5 mg/mL |
| High-Throughput (96/384-Well) | Yes — plate-based, automated | No — sequential SEC runs | No — 7–12 samples per rotor, 3–8 h/run | Yes — capillary-based, 48 capillaries/run |
| Resolution | Low — cannot resolve close MW species | Medium — SEC separates by hydrodynamic volume | High — resolves species by mass and shape | N/A — measures thermal unfolding, not size |
| Best For | Rapid aggregation screening, developability triage, formulation screening, batch comparability | Absolute MW, oligomer quantification, aggregate MW determination | Aggregate quantification (regulatory gold standard), empty/full AAV ratio | Thermal stability ranking, buffer/pH screening for conformational stability |
Sample preparation & plate loading
Automated DLS acquisition
Autocorrelation & size distribution calculation
Thermal unfolding & aggregation analysis (optional)
kD determination (optional)
Report delivery & interpretation
DLS data quality depends on sample preparation, instrument settings, and interpretation criteria. Every measurement includes the following QC checks.
| QC Parameter | Acceptance Criteria | Action if Out of Spec |
| Autocorrelation Function Baseline | Smooth decay to baseline; no oscillations or noise spikes | Check for dust, air bubbles, or insufficient signal; re-filter or increase acquisition time |
| Count Rate Stability | Count rate within expected range for sample concentration; stable across acquisitions | Fluctuating count rate indicates aggregates forming or settling — check sample stability |
| Polydispersity Index (PDI) | 0.3: highly polydisperse / aggregated | PDI >0.3 triggers orthogonal verification by SEC-MALS or AUC before aggregation is concluded |
| Size Distribution Reproducibility | Rh ±5% across triplicate measurements; peak positions consistent | >5% variation indicates sample heterogeneity or instrument instability — re-measure with fresh aliquot |
| Dust/Particulate Contamination | No sharp spikes in the >1 µm region of the intensity distribution | Presence of spikes → re-filter sample (0.22 µm) and re-measure; document in report |
| Thermal Ramp Linearity | Temperature ramps: ±0.2°C from setpoint throughout the experiment | >0.2°C deviation → instrument recalibration before sample measurement |
| Parameter | Specification |
| Sample Types | Purified proteins (mAbs, bispecifics, Fc-fusions, enzymes), peptides, AAV, LNPs, liposomes, polymeric nanoparticles, VLPs, protein conjugates |
| Concentration Range | 0.1–100 mg/mL (protein); optimal 1–10 mg/mL for standard measurement; 0.5–5 mg/mL for kD analysis |
| Sample Volume | Plate-based (96/384/1536): 2–4 µL per well; Cuvette: 20–100 µL; Thermal ramp: 20 µL minimum (sealed plate) |
| Purity | ≥90% by SDS-PAGE; aggregates do not preclude measurement but will be reported; free of dust/particulates (filterable ≤0.22 µm) |
| Buffer Compatibility | Tris, HEPES, PBS, phosphate, citrate, acetate, histidine; detergents ≤0.1% (may contribute to scattering); glycerol ≤10%; DMSO ≤2% |
| Filtration | 0.22 µm filtration or 10,000g × 10 min centrifugation required to remove dust — the most common source of DLS artifacts |
| Shipping | Purified proteins: ship on dry ice; pre-formulated samples: ship frozen; avoid repeated freeze-thaw cycles (document number of cycles) |
Dust is the single largest source of DLS artifacts — a single 5 µm dust particle scatters ~10¹²× more light than a 5 nm protein. We recommend filtering all samples immediately before loading, and we verify count rate stability as a QC gate before data is accepted.
Size Distributions, Thermal Stability Curves, and Colloidal Stability Parameters
Every DLS project includes a complete data package with annotated size distributions, thermal ramp plots, and expert interpretation.
Size Distribution & PDI Analysis
Intensity, volume, and number-weighted size distribution plots for each sample. Z-average Rh, PDI, and peak analysis with % area for each population. QC metrics including count rate, autocorrelation function fit quality, and baseline.
Thermal Stability Profiles
Rh and scattering intensity vs. temperature plots. Tonset (first aggregation), Tagg (aggregation midpoint), and Tsize (size transition) values annotated. Isothermal stability data at user-specified temperatures with time-course Rh and PDI.
Colloidal Stability Parameters
Diffusion coefficient vs. concentration plot with linear regression — kD value with 95% confidence interval. Colloidal stability classification (stable / borderline / aggregation-prone) based on kD sign and magnitude. B22 from complementary SLS where applicable.
What PDI value indicates a "good" protein sample?
A PDI below 0.1 indicates a monodisperse sample — well-behaved and suitable for development. PDI between 0.1 and 0.3 indicates moderate polydispersity — the sample may contain oligomers or multiple conformational states. PDI above 0.3 flags significant size heterogeneity, likely aggregation, and should trigger investigation by orthogonal methods (SEC-MALS, AUC) before the candidate is advanced. These thresholds are guidelines, not absolute cutoffs — a PDI of 0.15 may be acceptable for an inherently flexible protein, while a PDI of 0.08 may be expected for a rigid mAb.
Why does DLS detect aggregates that SEC misses?
Three reasons: (1) DLS intensity scales with the sixth power of particle radius — a 0.1% population of 100 nm aggregates dominates the scattering signal and is easily detected. (2) SEC dilutes the sample 10–50× during chromatography, which can dissociate reversible aggregates. (3) SEC columns and frits can filter out larger aggregates before they reach the detector. DLS measures the sample directly in its native concentration and buffer — without dilution, separation, or filtration — preserving the aggregation state as it exists in solution. This is why DLS is recommended as a first-line screening tool, with SEC-MALS or AUC deployed as confirmatory methods for samples that pass the DLS screen.
What does a negative kD value mean for my protein?
A negative kD indicates net attractive protein–protein interactions — as concentration increases, proteins are more likely to self-associate, leading to aggregation, high viscosity, or phase separation at the high concentrations required for subcutaneous delivery (>100 mg/mL). A positive kD indicates net repulsive interactions — the protein is colloidally stable and likely to remain monodisperse at high concentration. kD is measured from DLS at 5–8 concentrations (typically 1–10 mg/mL) and predicts behavior at >100 mg/mL — enabling formulation decisions months before high-concentration material is available. For reference, marketed mAbs typically have kD values between −10 and +20 mL/g; values below −20 mL/g are considered high risk for developability.
How is DLS different from nanoDSF for stability screening?
DLS measures colloidal stability — whether the protein remains monodisperse or aggregates in solution. nanoDSF measures conformational stability — whether the protein maintains its folded structure at increasing temperature (Tm, Tonset of unfolding). A protein can have excellent conformational stability (high Tm) but poor colloidal stability (aggregates before unfolding), or vice versa. The two techniques are complementary, not redundant. The industry best practice — adopted from NanoTemper's developability workflow — is to use DLS for aggregation screening and nanoDSF for thermal unfolding, together providing orthogonal stability data that neither technique alone can supply.
Can DLS be used for AAV and LNP samples?
Yes. DLS is widely used in gene therapy development for AAV capsid aggregation screening, empty/full capsid size comparison (though it cannot resolve the two populations — AUC is required for that), and LNP size/PDI/stability profiling. For AAV, DLS detects pre-existing aggregates and monitors thermal stability in formulation buffer — critical quality attributes because aggregated AAV has reduced transduction efficiency and increased immunogenicity risk. For LNPs, DLS provides rapid size and PDI feedback during formulation development — a full 96-well formulation screen can be completed in under 2 hours. DLS is non-destructive; the sample is recovered after measurement for orthogonal analysis by AUC, SEC-MALS, or TEM if needed.
How much sample do I need for a full DLS screening study?
A standard plate-based DLS measurement consumes 2–4 µL per well. For a typical 96-well formulation screen (e.g., 8 pH levels × 12 excipient conditions), the total sample requirement is approximately 200–400 µL of protein at the desired concentration. For kD analysis (5–8 concentrations × triplicate), approximately 50–100 µL total is needed. Thermal ramp measurements require 20 µL per condition. DLS has the lowest sample consumption of any biophysical stability technique — a 1 mL aliquot at 1 mg/mL can support a full screening campaign across dozens of conditions.
Forder, J.K. (2024). Self-interactions and aggregation of therapeutic proteins. Doctoral Dissertation, University of Delaware. UD Space Repository
— Comprehensive study linking DLS/SLS-measured kD and B22 to irreversible aggregation, high viscosity, phase separation, and long-term storage stability of mAbs and Fc-fusion proteins.
Rodriguez-Loya, J. et al. (2024). Dynamic light scattering and its application to control nanoparticle aggregation in colloidal systems: A review. Micromachines. 15(1):24. DOI: 10.3390/mi15010024
— Review of DLS fundamentals, correlation functions, CONTIN/NNLS algorithms, and practical strategies for monitoring and controlling aggregation.
NanoTemper Technologies (2023). How early discovery and development teams use dynamic light scattering to de-risk downstream biologics development. NanoTemper Blog. Link
— Industry best-practice guidance for DLS-based developability screening: first-pass triage, candidate ranking, and multiparameter stability assessment.
Stetefeld, J. et al. (2016). Dynamic light scattering: a practical guide and applications in biomedical sciences. Biophysical Reviews. 8(4):409-427. DOI: 10.1007/s12551-016-0218-6
— Practical guide to DLS sample preparation, data acquisition, and interpretation — widely cited reference for DLS method standardization.
Minton, A.P. (2016). Recent applications of light scattering measurement in the biological and biopharmaceutical sciences. Analytical Biochemistry. 501:4-22. DOI: 10.1016/j.ab.2016.02.007
— Reviews the application of DLS and SLS to protein interactions, aggregation, and developability assessment in biopharmaceutical development.
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