40 nm ''Lateral-Flow-Easy'' Gold Nanoparticles

Overview:

NanoBrand 40 nm Gold Nanoparticles “Lateral‑Flow‑Easy” are highly monodisperse nano‑spheres specifically engineered for lateral flow assays (LFAs) and other immunochromatographic formats. Their tight size distribution and optimized surface chemistry deliver high‑contrast test and control lines with minimal background, supporting robust assay development, validation, and scale‑up for diagnostic applications.

These LFA‑grade gold nanoparticles combine excellent monodispersity (CoV ≤ 5% for 5nm and larger particles; PdI ≤ 0.1) with carefully tuned optical and flow properties to ensure predictable performance on nitrocellulose and other LFA membranes. Uniform size leads to consistent localized surface plasmon resonance (LSPR) and a stable, intense red color signal that is critical for visual detection, while avoiding the diffuse or inconsistent colors associated with more polydisperse colloids.

Particle and Surface Properties:

Core diameter 40 nm, narrow size distribution

CoV (polydispersity): ≤ 5% (compared with CoV ≈ 12–15% commonly available)

Polydispersity index: PdI ≤ 0.1 (versus PdI ≤ 0.2 typically offered)

Learn Why is Monodispersity Important.

Morphology: spherical gold nanoparticles (nanospheres), no other shapes. 

Surface options: citrate‑coated formulation or PEG‑COOH (thiol‑PEG‑carboxylate).

Matrix: reactant‑free aqueous colloidal suspension, low ionic strength

Find out Why should Stabilizing agents be Avoided.

Optical density and concentration: tuned for conjugation performance and membrane flow

Supplied with: Lot-specific Certificate of Analysis including TEM images, size distribution, UV-vis spectra, PdI, hydrodynamic diameter, Zeta-potential, and relevant QC data.

Consult a typical CoA for 40nm Gold Nano-Spheres, PEG5K-CARB, OD=50 and CoA for 40nm Gold Nano-Spheres, Citrate, OD=20.

PEG‑Carboxylate Surface

For PEGylated “Lateral‑Flow‑Easy” variants, PEG chains are attached via gold–thiol bonds, leaving terminal carboxyl groups available for covalent coupling. This highly stable coating offers excellent resistance to nonspecific protein adsorption, high‑salt and pH stability, and enables EDC/NHS coupling to amine‑containing proteins and biomolecules for preparation of stable, covalent conjugates.

Learn more about Gold Nanoparticles in Biosensing and Personalized Medicine.

Advantages in Lateral Flow Assays:

Consistent Optical Properties

Monodisperse 40 nm gold nano‑spheres exhibit uniform LSPR characteristics, resulting in a stable and predictable red color on LFA test and control lines. This consistency improves readability, reduces assay‑to‑assay variability, and is particularly important for commercial diagnostic tests where visual clarity and user confidence are critical.

Improved Sensitivity and Limit of Detection

The uniform size of these nanoparticles supports optimal binding efficiency to antibodies, antigens, and other biomolecular recognition elements. Enhanced per‑particle signal and strong plasmonic absorption at the test line translate into improved analytical sensitivity and lower limits of detection compared with polydisperse or non‑optimized colloidal gold.

Enhanced Reproducibility and Flow Dynamics

Highly monodisperse particles ensure consistent conjugation with recognition elements and reproducible capillary flow through nitrocellulose membranes. This minimizes batch‑to‑batch variation in conjugate performance, reduces the risk of clogging or uneven particle distribution, and supports dependable scale‑up from R&D to pilot and full‑scale manufacturing.

High Colloidal Stability

Reactant‑free dispersions with controlled surface chemistry yield high colloidal stability and reduced aggregation risk. Stable particles maintain their optical properties and mobility during storage and throughout the assay, preventing false signals, flow issues, or performance drift over time.

Tunable Size and Surface for Assay Optimization

Within the “Lateral‑Flow‑Easy” product line, gold nanoparticles can be synthesized at specific diameters and supplied with different concentrations and PEG spacer lengths. This tunability allows researchers and manufacturers to optimize signal strength, flow behavior, and conjugation strategy for particular analytes, membrane types, and assay formats.

Explore more about the Benefits of monodisperse gold nanoparticles for LFAs.

Conjugation to Antibodies and Proteins

The citrate surface provides a controlled starting point for passive adsorption–based conjugation, with pH‑dependent binding optimized to support consistent antibody orientation and surface coverage. PEG‑COOH surfaces, in turn, enable covalent attachment of amine‑containing biomolecules via EDC/NHS chemistry, giving users flexibility to select the conjugation approach that best fits their LFA design, stability requirements, and regulatory strategy.

Manufacturing and Scale‑Up Consistency

“Lateral‑Flow‑Easy” 80 nm gold nanoparticles are manufactured under tightly controlled synthesis and quality‑control procedures, including routine measurement of CoV, PdI, hydrodynamic diameter, Zeta potential, and other characteristic parameters. This high level of reproducibility simplifies technology transfer from research to commercial manufacturing and reduces the need to re‑optimize conjugation, blocking, or strip‑coating parameters when changing lots or scaling up production.

Storage and Expiration

- Citrate‑coated “Lateral‑Flow‑Easy” nanoparticles: store at 4–25 °C, protected from light. Do not freeze. Shake or gently invert the bottle before use.

- PEG‑COOH “Lateral‑Flow‑Easy” nanoparticles: store at 2–8 °C, protected from light. Do not freeze. Shake or gently invert before use.

Products can typically be used for at least one year under recommended storage conditions. For extended storage, measuring UV‑Vis spectra is recommended to confirm colloidal and optical stability. Storage at the lower end of the temperature range is preferable to maximize shelf life.

Safety and Handling

NanoBrand does not guarantee the suitability of its products for any particular application. It is the customer’s responsibility to ensure that the product is appropriate and permitted for the intended use, in accordance with applicable regulations and internal quality systems. Please consult our Terms of Service and follow institutional guidelines for the safe handling and disposal of nanomaterials.

For “Lateral‑Flow‑Easy” gold nanoparticle products, customized diameters, concentrations, and PEG spacer sizes are available on request to support assay optimization, OEM production, and private‑label diagnostic development.

Go back to Gold Nanoparticles for Lateral Flow Assays.

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