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MSD NfL (Neurofilament Light) Testing

MSD S-PLEX · fg/mL Sensitivity

MSD NfL (Neurofilament Light) Assay Service

Quantify Neurofilament Light chain at femtogram-per-milliliter sensitivity — the leading fluid biomarker for axonal injury and neurodegeneration across multiple neurological conditions.

Unlike disease-specific markers, NfL reflects the shared final pathway of axonal degeneration — making it one of the most versatile biomarkers in neurodegeneration research. From multiple sclerosis and ALS to Alzheimer's and TBI, plasma NfL tracks neuronal injury across the disease spectrum. MSD S-PLEX delivers the fg/mL sensitivity needed for reliable quantification in both serum and plasma.

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NfL — The Universal Biomarker of Axonal Injury

Neurofilament Light chain (NfL) is the smallest subunit of neurofilaments — the type IV intermediate filament proteins that form the primary structural scaffold of the neuronal cytoskeleton. Expressed abundantly in large-caliber myelinated axons, NfL is released into the extracellular space following axonal damage or degeneration, regardless of the underlying etiology. Measurable in both cerebrospinal fluid (CSF) and blood, NfL has emerged as a sensitive, quantitative, and disease-agnostic biomarker of neuronal injury.

 Why NfL Is the Most Versatile Neurodegeneration Biomarker
Cross-disease applicability: NfL is elevated across a remarkably broad spectrum of neurological conditions — Alzheimer's disease, multiple sclerosis, ALS, frontotemporal dementia, traumatic brain injury, Huntington's disease, Parkinson's disease, and more. This makes it a powerful research tool for studies spanning multiple disease areas.
Quantitative injury readout: Blood NfL concentration correlates with the magnitude of axonal damage, providing a continuous, quantitative measure of ongoing neurodegeneration in research settings.
Prognostic value: Published studies demonstrate that elevated baseline NfL predicts future brain atrophy, cognitive decline, and disease progression across multiple neurological disorders.
Treatment response monitoring: NfL reductions have been observed in response to disease-modifying therapies in multiple sclerosis research, supporting its use as a pharmacodynamic biomarker in therapeutic development programs.
Blood-based accessibility: The strong correlation between CSF and blood NfL enables non-invasive, repeat-measure longitudinal research designs that are impractical with lumbar puncture.

Research Applications Across Disease Areas

Alzheimer's disease research — NfL complements amyloid and Tau biomarkers by capturing the neurodegenerative component of AD pathology; elevated NfL predicts faster cognitive decline in amyloid-positive research cohorts.
Multiple sclerosis research — NfL is one of the most extensively studied blood biomarkers in MS; levels correlate with MRI lesion load, relapse activity, and treatment response to disease-modifying therapies.
Amyotrophic lateral sclerosis research — baseline NfL levels correlate with disease progression rate and survival in ALS research cohorts.
Frontotemporal dementia research — NfL distinguishes FTD from primary psychiatric disorders and tracks disease intensity in longitudinal observational studies.
Traumatic brain injury research — serum NfL reflects the severity of axonal injury following concussion and repetitive head impacts; widely studied in sports-related concussion and military TBI research programs.
Cross-disease comparative research — NfL's pan-disease signal enables head-to-head comparisons of neurodegenerative burden across different pathologies in large cohort studies.

NfL Assay Performance

Representative performance metrics from peer-reviewed studies using blood NfL for neurodegeneration research across multiple disease areas.

0.87 AUC

MS vs. Healthy Controls
(Representative published value)

~2.5% /yr

Age-Related NfL Increase
In healthy adults >60 yr

≥5×

Elevation After Severe TBI
vs. pre-injury baseline

Note: Values are illustrative and drawn from published literature for informational purposes. Individual study results vary by cohort, assay platform, and pre-analytical protocols. These metrics do not constitute performance claims for clinical diagnostic use.

Standard Curve & Linearity

8-point calibration curve with R² ≥ 0.99 across the full dynamic range. Recombinant NfL calibrator traceable to international reference material. Dilution linearity verified at 1:2, 1:4, and 1:8 in serum and EDTA plasma matrices.

Precision & Reproducibility

Intra-plate CV <8% across low, medium, and high QC samples. Inter-plate CV <12%. Three independent QC levels run in duplicate on each plate. Lot-to-lot bridging data available for longitudinal studies.

Sample Stability

NfL is exceptionally stable — resistant to 24 hr at RT, 7 days at 4°C, and ≥3 years at −80°C with minimal signal loss. Up to 4 freeze-thaw cycles with <5% degradation. Compatible with serum, EDTA plasma, and citrate plasma collection tubes.

How MSD S-PLEX Detects NfL at fg/mL

Why standard immunoassays are insufficient — and how electrochemiluminescence addresses the sensitivity gap for blood NfL research.

The Sensitivity Challenge

Blood NfL circulates at approximately 5–20 pg/mL in healthy adults and 15–500+ pg/mL in individuals with active neurodegeneration, depending on the disease and severity. Conventional ELISA typically has an LLOQ of 15–30 pg/mL — barely sufficient to distinguish normal from mildly elevated levels. Longitudinal studies tracking subtle NfL changes within an individual require the fg/mL resolution that only ultra-sensitive platforms can provide.

The S-PLEX Solution

1. High-Capacity Carbon Electrode Surface

MSD's proprietary carbon electrode provides ~10× higher binding capacity than polystyrene, capturing more NfL molecules per well and extending the measurable range into the fg/mL domain.

2. SULFO-TAG ECL Label

Non-enzymatic, chemically stable label that emits light only upon electrical stimulation at the electrode surface. Zero background from unbound detection antibody or sample autofluorescence — critical for detecting ultra-low NfL concentrations.

3. S-PLEX Signal Amplification

An additional antibody amplification layer multiplies the number of SULFO-TAG labels per captured NfL molecule, pushing the lower limit of detection into the sub-pg/mL range and enabling reliable quantification of baseline NfL levels in healthy research populations.

4. Electrical Excitation

ECL signal is generated only when voltage is applied to the electrode — no excitation light source means no autofluorescence, light scattering, or photo-bleaching artifacts. This is particularly important for NfL, where matrix interference in serum can confound optical detection methods.

S-PLEX NfL Assay Specifications

TechnologyMSD S-PLEX (ECL)

AnalyteNeurofilament Light (NfL)

LOD<0.05 pg/mL (fg/mL)

LLOQ~0.1 pg/mL

Dynamic Range0.1–10,000 pg/mL (5+ logs)

Sample Volume25 µL per well

Recommended MatrixSerum, EDTA Plasma

Acceptable MatricesCSF, Citrate Plasma (on consultation)

Intra-Assay CV<8%

Inter-Assay CV<12%

Plate Format96-well MULTI-ARRAY

Read Time~70 seconds/plate

NfL vs Other Neurodegeneration Biomarkers

Versatility across disease areas in published research cohorts (broader applicability = higher score)

NfL 5/5

GFAP 3/5

p-Tau217 2/5*

UCH-L1 3/5

Aβ42/Aβ40 1/5*

Total Tau 3/5

* p-Tau217 and Aβ42/Aβ40 are highly disease-specific (Alzheimer's). Scores reflect cross-disease versatility in neurodegeneration research — not absolute utility. For research reference only.

NfL Assay Service Details

Service package, sample requirements, and deliverables.

Service Package

Item	Full Service	Kit Only
Sample Processing	Included	— Self-run
Standard Curve	8-point, each plate	Reagents provided
QC Samples	3 levels, duplicate	— User-prepared
Data Analysis	Full report	— Self-analysis
Raw Data	Included	— Instrument-dependent

For Research Use Only. Not for diagnostic procedures.

Sample Submission Requirements

Preferred MatrixSerum or EDTA Plasma

AcceptableCSF, Citrate Plasma (consultation required)

Typical Sample Volume50–200 µL per aliquot; as low as 25 µL per well. We'll advise based on your panel.

CollectionSerum: clot 30 min → 1,500×g/10 min → aliquot → −80°C; Plasma: EDTA tube → 1,500×g/10 min → aliquot → −80°C

ShippingDry ice, overnight courier

DocumentationSample manifest form (provided)

How to Get Started

Consult

Tell us about your study — samples, timeline, analytes of interest. We''ll recommend the optimal panel configuration.

Ship

Send your samples on dry ice. We provide collection kits and customs support for international shipments.

Receive Data

Receive your complete data package — quantitative report, raw data, and publication-ready methods.

Testing a hypothesis or new to this assay? Ask about a pilot feasibility run with a subset of samples before committing to a full study.

NfL Detection: MSD S-PLEX vs Other Platforms

Platform comparison for research applications.

Feature	MSD S-PLEX (ECL)	Simoa (Quanterix)	Conventional ELISA	LC-MS/MS
Sensitivity (LOD)	fg/mL	fg/mL	~15–30 pg/mL	~5–10 pg/mL
Dynamic Range	5–6 logs	4–5 logs	2–3 logs	3–4 logs
Sample Volume	25 µL	~100 µL	100 µL	250–500 µL
Multiplex Capability	Up to 10-plex	Up to 4-plex	Single-plex only	Targeted panels
Throughput	96-well / 70 sec read	~60 samples/hr	96-well batch	Low (~20/day)
Matrix Tolerance	High	Moderate	Low–Moderate	High
Best Research Fit	Cohort studies, trials, multiplex neuro panels	Ultra-low single markers, rare matrices	Small pilot studies	Isoform-specific work

For a detailed head-to-head analysis covering all neuro biomarkers, see our MSD vs Simoa: Ultra-Sensitive Immunoassay Platform Comparison.

What You Receive

Quantitative report — analyte concentrations, QC metrics, standard curve parameters (Excel + PDF)
Raw ECL data — per-well signal values, plate maps, curve plots — analysis-ready formats
Methods summary — ready for manuscript Methods or supplementary materials
QC documentation — intra/inter-plate CV, LOD/LLOQ, dilution linearity verification
Sample tracking log — receipt to analysis chain-of-custody
Consultation — post-delivery call to discuss results and interpretation as needed

Why Our Clients Choose Us

Assay expertise — dedicated scientist assigned to your project, not a rotating team
Flexible delivery — full-service or kit-only; custom U-PLEX combinations available
No-surprise QC — all QC results reported transparently; flagged values with explanations, never silently removed
Publication track record — data generated on our platform appears in peer-reviewed journals
Longitudinal consistency — reagent lot tracking across timepoints for multi-year cohort studies
Direct communication — talk to the scientist running your assay, not a project manager

Supporting Publications

Published research supporting NfL as a cross-disease biomarker of axonal injury.

Khalil M, Teunissen CE, Otto M, et al. (2018) Nature Reviews Neurology. 14(10):577–589. "Neurofilaments as biomarkers in neurological disorders." DOI: 10.1038/s41582-018-0058-z · PMID: 30171200

Mattsson N, Andreasson U, Zetterberg H, et al. (2017) JAMA Neurology. 74(5):557–566. "Association of Plasma Neurofilament Light With Neurodegeneration in Patients With Alzheimer Disease." DOI: 10.1001/jamaneurol.2016.6117 · PMID: 28346578

Disanto G, Barro C, Benkert P, et al. (2017) Annals of Neurology. 81(6):857–870. "Serum Neurofilament Light: A Biomarker of Neuronal Damage in Multiple Sclerosis." DOI: 10.1002/ana.24954 · PMID: 28512753

Benatar M, Wuu J, Andersen PM, et al. (2018) Neurology. 91(12):e1175–e1185. "Neurofilament light: A biomarker of disease activity and treatment response in presymptomatic ALS." DOI: 10.1212/WNL.0000000000006207

Shahim P, Gren M, Liman V, et al. (2016) Scientific Reports. 6:36791. "Serum neurofilament light protein predicts clinical outcome in traumatic brain injury." DOI: 10.1038/srep36791 · PMID: 27819296

Rohrer JD, Woollacott IO, Dick KM, et al. (2016) Neurology. 87(13):1329–1336. "Serum neurofilament light chain protein is a measure of disease intensity in frontotemporal dementia." DOI: 10.1212/WNL.0000000000003154 · PMID: 27581216

References for informational context. For Research Use Only.

NfL Assay FAQ

Is this NfL assay validated for clinical diagnostic use?

No. This NfL assay is manufacturer-validated for research use only (RUO). It is suitable for preclinical studies, cohort research, biomarker discovery, and therapeutic development applications. It is not validated for clinical diagnostic procedures, patient management decisions, or as a standalone screening tool in a clinical setting. All data is reported with the explicit disclaimer that it should not be used as the sole basis for clinical decision-making.

What sample types are compatible with the NfL assay?

The assay is compatible with serum and EDTA plasma as preferred matrices. CSF and citrate plasma can also be accommodated on consultation. Importantly, serum and plasma NfL values are highly correlated (r > 0.90 in published studies), though absolute values may differ slightly between matrices. We strongly recommend consistent matrix use within a study. Matrix-specific normative reference data are available to support interpretation.

How does NfL differ from disease-specific biomarkers like p-Tau217?

NfL is a non-specific marker of axonal injury — it reflects the downstream consequence of neurodegeneration regardless of the underlying etiology. In contrast, p-Tau217 is a pathology-specific marker strongly associated with Alzheimer's disease amyloid and Tau pathology. This makes NfL and p-Tau217 complementary: NfL tells you how much neurodegeneration is occurring, while p-Tau217 tells you why (in the case of AD). Many research programs combine both biomarkers for a comprehensive picture. The optimal choice depends on your specific research question — NfL for pan-disease neurodegeneration studies, p-Tau217 for Alzheimer's-specific investigations.

Can NfL be combined with other biomarkers in a multiplex panel?

Yes. Through MSD's U-PLEX custom platform, NfL can be combined with up to 9 other biomarkers in a single well. Common combinations include: NfL + GFAP + p-Tau217 (neurodegeneration 3-plex), and NfL + Aβ40 + Aβ42 + p-Tau217 (comprehensive AD pathology panel). Note that for maximum sensitivity (fg/mL range), the S-PLEX single-plex format is recommended. Contact us to determine the optimal configuration for your research objectives.

What is the effect of age on NfL levels?

Blood NfL concentrations increase with age in healthy adults — approximately 2.2–3.3% per year after age 60 according to published population-based studies. This age-dependence is an important consideration for study design. We provide age-stratified reference ranges to support appropriate interpretation. For longitudinal studies, each participant serves as their own control, which mitigates age effects. Cross-sectional studies should include age-matched control groups. Our scientific team can advise on study design strategies to account for age-related NfL variation.

How should I prepare and ship samples for NfL analysis?

For serum: collect in serum separator tubes → allow to clot for 30 minutes at room temperature → centrifuge at 1,500×g for 10 minutes at 4°C → transfer to labeled polypropylene cryovials → freeze immediately at −80°C. For plasma: collect in EDTA tubes → centrifuge at 1,500×g for 10 minutes at 4°C → transfer plasma to labeled polypropylene cryovials → freeze immediately at −80°C. Ship on dry ice via overnight courier with a completed sample manifest form. Avoid repeated freeze-thaw cycles. NfL is a robust protein with excellent freeze-thaw stability, but consistent pre-analytical handling is essential for reliable data. Contact us for a detailed sample collection and shipping guide.

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