100nm Quantum Dot Microspheres HQD610-100 1%

100 nm Quantum Dot Microspheres HQD610-100

SHBC HQD610-100 Quantum Dot Microspheres are highly fluorescent nanoparticles developed for immunoassay research, fluorescence lateral flow assay development, biomarker detection and large-scale diagnostic reagent manufacturing.

The microspheres have a nominal particle size of 100 nm, a solids content of 1% and a fluorescence emission peak centered at approximately 610 nm. Multiple quantum dots are incorporated into each microsphere to generate a strong and stable orange-red fluorescent signal under suitable excitation conditions.

Compared with free quantum dots or conventional organic fluorescent dyes, quantum dot-loaded microspheres provide a practical particle platform for biomolecule conjugation, membrane migration, signal amplification and quantitative fluorescence detection.

HQD610-100 is intended for research institutions, IVD reagent developers and immunoassay manufacturers that require consistent fluorescent microspheres from assay feasibility studies through pilot production and commercial-scale reagent manufacturing.

Product Overview

HQD610-100 combines the optical properties of quantum dots with the handling and surface chemistry advantages of polymer microspheres.

Quantum dots provide bright fluorescence, a broad excitation range, a relatively narrow emission profile and good resistance to photobleaching. Incorporating multiple quantum dots into a microsphere can increase the total fluorescent signal generated by each labeling particle while also providing a functional particle surface for antibody, antigen, protein or oligonucleotide immobilization.

The nominal 100 nm particle size is suitable for immunoassay applications requiring a balance between fluorescence intensity, biomolecule loading, colloidal stability and migration performance.

HQD610-100 can be evaluated as a fluorescent signal label in lateral flow immunoassays, fluorescence-linked immunosorbent assays, microfluidic detection systems, biochips and other quantitative fluorescence platforms.

Key Features of HQD610-100

Bright 610 nm Fluorescence

HQD610-100 produces an orange-red fluorescence signal with an emission maximum centered at approximately 610 nm.

The 610 nm emission channel is compatible with many fluorescence readers used for quantitative immunoassays and lateral flow strip analysis. The relatively narrow emission profile can help improve channel separation and reduce interference from adjacent fluorescence signals when an assay is properly designed.

The actual fluorescence intensity obtained in a finished assay depends on the excitation source, optical filters, antibody loading, particle dosage, membrane material and sample matrix.

Uniform 100 nm Particle Size

The nominal 100 nm particle size provides a useful balance between available surface area and particle migration.

Smaller particles generally provide a high surface-area-to-volume ratio for biomolecule immobilization, while the controlled nanoscale size can support consistent capillary migration through suitable nitrocellulose membranes.

Particle size should be evaluated together with membrane pore structure, conjugate pad treatment, running buffer composition and sample viscosity during lateral flow assay development.

Stable Quantum Dot Encapsulation

Multiple quantum dots are incorporated into the microsphere structure instead of being used only as individual fluorescent nanocrystals.

This particle architecture is designed to:

• Increase the fluorescent signal generated by each labeling particle

• Protect the fluorescent material from direct exposure to the assay environment

• Improve particle handling during washing and conjugation

• Provide a practical surface for biomolecule immobilization

• Support more consistent fluorescence between particles

• Improve suitability for quantitative fluorescence detection

The encapsulated structure also helps reduce the risk of fluorescent material loss during routine washing, storage and assay operation.

Functionalized Surface for Biomolecule Coupling

HQD610-100 can be supplied with an application-compatible functional surface for biomolecule conjugation.

Depending on the selected surface chemistry, the microspheres may be used for the immobilization of:

• Monoclonal and polyclonal antibodies

• Recombinant proteins

• Antigens

• Peptides

• Enzymes

• Aptamers

• Oligonucleotides

• Other affinity ligands

Carboxyl-functionalized versions can be activated through EDC/NHS chemistry for covalent coupling to primary amine groups on antibodies and proteins.

Please confirm the surface functional group of the selected lot before establishing a conjugation protocol.

Stable Aqueous Dispersion

HQD610-100 is supplied as an aqueous microsphere suspension with a solids content of 1%.

The formulation is designed to support particle redispersion and routine assay development. Before use, the suspension should be mixed thoroughly to restore a uniform particle concentration.

Excessively strong or prolonged sonication should be avoided because it may affect the particle surface, fluorescent structure or biomolecule-coupling performance.

Lot-Controlled Supply for Reagent Manufacturing

HQD610-100 is developed for customers that need to move beyond small research quantities.

SHBC supports product evaluation, pilot-scale verification, lot reservation and bulk manufacturing for immunoassay reagent companies. Important product attributes can be controlled and documented according to the agreed specification, including particle size, solids content, fluorescence profile and surface functionality.

This approach helps reduce the risks associated with changing fluorescent labels during assay scale-up or commercial manufacturing.

Technical Specifications

Particle-size tolerance, fluorescence spectrum, surface chemistry, dispersion buffer, packaging and shelf life should be confirmed using the lot-specific specification or certificate of analysis.

How Quantum Dot Microspheres Work in Immunoassays

In a fluorescent immunoassay, HQD610-100 microspheres are conjugated to a recognition molecule such as an antibody, antigen or aptamer.

When the conjugated microspheres contact a sample, the immobilized recognition molecule binds to the target analyte. The resulting immune complex is captured at a detection zone, microplate surface, microfluidic channel or other solid-phase interface.

Under an appropriate excitation light source, the accumulated quantum dot microspheres emit fluorescence near 610 nm. A fluorescence reader measures the signal intensity and converts it into a qualitative, semi-quantitative or quantitative result.

A typical sandwich immunoassay contains:

1. An HQD610-100 microsphere conjugated to a detection antibody

2. A target analyte in the sample

3. A capture antibody immobilized at the test zone

4. A fluorescence reader configured for the excitation and emission channel

5. A calibration curve for quantitative analysis

For competitive assays, the assay architecture should be selected according to the molecular size of the analyte and the available antibody pair.

Recommended Applications

Fluorescence Lateral Flow Immunoassay

HQD610-100 can be used as a fluorescent reporter particle in lateral flow immunoassays for rapid and quantitative detection.

Potential application fields include:

• Infectious disease testing

• Inflammation biomarker detection

• Cardiac marker detection

• Hormone testing

• Food safety analysis

• Veterinary diagnostics

• Environmental monitoring

• Agricultural testing

• Drug residue detection

• Research-use point-of-care assays

Compared with purely visual colorimetric labels, fluorescent labels allow the test-line signal to be measured using a compatible fluorescence reader.

The final assay sensitivity depends on the antibody pair, particle conjugation, membrane selection, sample matrix, strip structure, running buffer and reader settings.

Quantitative Fluorescence Immunoassay

The stable 610 nm signal can support quantitative fluorescence detection in microplates, cartridges, test strips and automated immunoassay systems.

HQD610-100 may be evaluated for:

• Fluorescence-linked immunosorbent assays

• Sandwich fluorescence immunoassays

• Competitive fluorescence immunoassays

• Antigen and antibody detection

• Biomarker quantification

• High-sensitivity research assays

A standard curve should be established for every assay format and sample type.

Multiplex Biomarker Detection

Quantum dot materials can be manufactured with different emission wavelengths while being excited by a common or overlapping excitation source.

This property makes quantum dot microspheres useful for developing multiplex detection systems. Different microsphere populations may be distinguished according to their emission channels or fluorescence coding patterns.

HQD610-100 can serve as the 610 nm fluorescent channel in a properly designed multiplex panel.

Successful multiplex development requires careful selection of:

• Emission wavelengths

• Optical filters

• Particle concentrations

• Antibody combinations

• Capture-zone locations

• Cross-reactivity controls

• Signal compensation methods

Biochips, Biosensors and Microfluidic Platforms

The controlled particle size and fluorescent signal make HQD610-100 suitable for evaluation in miniaturized analytical systems.

Potential platforms include:

• Microfluidic immunoassay cartridges

• Fluorescence biochips

• Microarray detection systems

• Optical biosensors

• Lab-on-a-chip devices

• Portable fluorescence readers

• Automated point-of-care analyzers

Particle compatibility with channels, pumps, valves and optical detection modules should be confirmed during system development.

Biomolecule Labeling and Tracing

HQD610-100 may also be evaluated as a fluorescent particle label for biomolecule tracing, cell-related research and fluorescence imaging applications.

For cell-based applications, researchers should independently assess cytotoxicity, uptake behavior, nonspecific binding and compatibility with the selected biological model.

Why Choose 100 nm Quantum Dot Microspheres

Particle size can influence conjugation capacity, colloidal stability, membrane migration, sedimentation behavior and fluorescent signal.

The 100 nm size is frequently selected for fluorescent immunoassay development because it can provide:

• High available surface area for biomolecule immobilization

• Strong fluorescence from multiple quantum dots per particle

• Controlled migration through suitable lateral flow membranes

• Lower sedimentation tendency than large microspheres

• Compatibility with common conjugate-pad treatment processes

• A useful starting point for quantitative assay optimization

However, the optimum particle size is application-dependent.

A 100 nm particle may perform well in one membrane or sample matrix but require additional optimization in another. Developers should compare membrane types, antibody loading levels, particle dosages and running buffers before selecting the final formulation.

Quantum Dot Microspheres vs. Other Signal Labels

No signal label is universally optimal for every immunoassay.

The final selection should be based on the target detection limit, assay format, sample matrix, reader platform, manufacturing cost and required storage stability.

Antibody Conjugation and Assay Development

Coupling of Carboxyl-Functionalized Microspheres

For a carboxyl-functionalized version of HQD610-100, antibodies or proteins can typically be immobilized through EDC/NHS-mediated amide-bond formation.

A general development workflow includes:

1. Resuspend the microspheres thoroughly.

2. Transfer the required quantity to a low-binding reaction tube.

3. Wash or exchange the microspheres into a suitable activation buffer.

4. Add freshly prepared EDC and NHS to activate the surface carboxyl groups.

5. Incubate under controlled mixing conditions.

6. Remove excess activation reagents.

7. Add the antibody or protein in a suitable coupling buffer.

8. Incubate for the required coupling time.

9. Block remaining active sites.

10. Wash the conjugated microspheres.

11. Resuspend the conjugate in an optimized storage buffer.

12. Evaluate fluorescence, recovery, binding activity and colloidal stability.

The exact EDC/NHS ratio, antibody dosage, pH, reaction time and blocking reagent must be optimized for each biomolecule.

Recommended Assay Optimization Workflow

A structured optimization plan can reduce development time and material consumption.

Stage 1: Material characterization

Confirm particle size, fluorescence spectrum, solids content, surface group and initial dispersion stability.

Stage 2: Conjugation screening

Compare antibody-to-particle ratios, activation conditions, coupling buffers and blocking reagents.

Stage 3: Conjugate-pad optimization

Evaluate pad material, pretreatment buffer, sugar stabilizers, surfactants and drying conditions.

Stage 4: Membrane screening

Compare nitrocellulose membranes with different capillary-flow rates and protein-binding capacities.

Stage 5: Running-buffer optimization

Adjust pH, ionic strength, protein blockers, surfactants and viscosity modifiers.

Stage 6: Particle dosage optimization

Determine the minimum particle dosage that provides the required signal without increasing background or slowing migration.

Stage 7: Reader configuration

Confirm the excitation source, emission filter, exposure time, gain and signal-processing algorithm.

Stage 8: Sample-matrix validation

Test negative samples, positive samples, interfering substances and samples covering the expected clinical or analytical range.

Stage 9: Stability verification

Evaluate conjugate stability, strip stability, accelerated stability and real-time storage performance.

Important Variables Affecting Assay Performance

Quantum dot microspheres can provide a strong fluorescent label, but final assay performance is controlled by the entire detection system.

Important variables include:

• Antibody affinity and specificity

• Antibody orientation after conjugation

• Steric hindrance on the particle surface

• Antibody loading density

• Particle aggregation

• Buffer pH and ionic strength

• Type and concentration of surfactant

• Blocking reagent

• Nitrocellulose membrane selection

• Sample viscosity

• Sample autofluorescence

• Fluorescence-reader sensitivity

• Excitation and emission filter matching

• Test-line capture density

• Reaction and migration time

Using an excessive antibody loading level may not always improve assay performance. Dense surface coverage can increase steric hindrance or reduce the accessibility of antigen-binding sites.

A conjugation screening experiment is therefore recommended before selecting the final production formula.

Quality Control for Batch Production

For immunoassay manufacturers, lot-to-lot consistency is as important as the initial fluorescence intensity.

Recommended quality-control parameters for quantum dot microspheres include:

• Particle-size distribution

• Hydrodynamic particle size

• Polydispersity

• Solids content

• Fluorescence emission peak

• Relative fluorescence intensity

• Fluorescence spectrum width

• Surface functional-group consistency

• Zeta potential, when applicable

• Appearance and dispersion condition

• Redispersion performance

• Short-term temperature stability

• Storage stability

• Conjugation recovery

• Functional binding performance

• Microbial-control requirements, when specified

SHBC can discuss customer-specific quality-control items and acceptance criteria for pilot and bulk production.

For commercial reagent projects, customers are encouraged to establish a retained reference lot and evaluate new production lots against the same conjugation and assay protocol.

Customization and Bulk Manufacturing Support

Different immunoassay systems may require different optical, chemical and physical particle properties.

SHBC provides customization support based on project requirements, including:

• Alternative particle sizes

• Different fluorescence emission wavelengths

• Carboxyl-functionalized surfaces

• Amine-functionalized surfaces

• Streptavidin-functionalized surfaces

• Customized solids content

• Customized dispersion buffer

• Customized preservative system

• Low-background surface treatment

• Application-specific packaging

• Pilot-batch production

• Bulk manufacturing

• Lot reservation

• OEM and ODM services

For a new project, customers should provide the intended assay format, target analyte, sample matrix, reader wavelength, required detection limit, preferred surface chemistry and estimated annual demand.

These details allow the technical team to recommend a more appropriate product configuration and evaluation plan.

Storage and Handling

Recommended handling practices include:

• Store at 2–8°C unless otherwise stated on the product label or certificate of analysis.

• Protect the product from direct light.

• Do not freeze.

• Avoid repeated freeze-thaw cycles.

• Mix thoroughly before sampling.

• Use clean, low-binding laboratory containers.

• Avoid contamination of the stock suspension.

• Do not expose the product to strong acids, strong alkalis or incompatible organic solvents.

• Avoid prolonged high-power sonication.

• Close the container immediately after use.

• Follow the lot-specific storage and expiration information.

If sedimentation occurs during storage, gently invert, vortex at a low setting or apply brief mild sonication until a uniform suspension is restored.

Do not use visible sedimentation alone as a product-failure criterion. Confirm whether the microspheres can be completely redispersed and whether their fluorescence and particle-size characteristics remain within specification.

Frequently Asked Questions

What is HQD610-100?

HQD610-100 is a quantum dot-loaded fluorescent microsphere suspension with a nominal particle size of 100 nm, a solids content of 1% and an emission peak centered at approximately 610 nm.

It is developed for immunoassay research, fluorescence lateral flow assay development and batch reagent manufacturing.

What does “610” mean in HQD610-100?

“610” refers to the approximate fluorescence emission wavelength of the microspheres.

The exact emission maximum and tolerance should be confirmed using the lot-specific fluorescence spectrum or certificate of analysis.

Why are quantum dots incorporated into microspheres?

Incorporating multiple quantum dots into a microsphere can increase the fluorescent signal generated by each labeling particle.

The microsphere structure also provides a practical surface for biomolecule conjugation and makes the fluorescent particles easier to wash, process and use in immunoassay manufacturing.

Can HQD610-100 be used in lateral flow assays?

Yes. HQD610-100 can be evaluated as a fluorescent signal label in lateral flow immunoassays.

Compatibility should be verified with the selected nitrocellulose membrane, conjugate pad, running buffer, sample type and fluorescence reader.

Is HQD610-100 suitable for quantitative detection?

Yes. A compatible fluorescence reader can measure the 610 nm signal and convert test-line fluorescence into quantitative results through a calibration curve.

The quantitative range and detection limit must be established for the individual assay.

How are antibodies coupled to the microspheres?

The coupling method depends on the surface chemistry.

Carboxyl-functionalized particles are commonly coupled to antibody amine groups through EDC/NHS chemistry. Amine-, streptavidin- or other functionalized particles require different coupling strategies.

Do quantum dot microspheres always provide better sensitivity than colloidal gold?

Not automatically.

Quantum dot microspheres can provide a strong measurable fluorescence signal, but the final sensitivity also depends on antibody quality, conjugation orientation, particle dosage, membrane selection, sample matrix and reader performance.

A side-by-side assay comparison is recommended.

Can HQD610-100 be used for multiplex detection?

Yes. HQD610-100 can serve as one fluorescence channel in a multiplex detection system.

Other particle populations with different emission wavelengths can be combined when the reader, filters and assay design provide sufficient spectral separation.

Can the particle size or fluorescence wavelength be customized?

Yes. SHBC can discuss customized particle sizes, emission wavelengths, surface chemistries, solids contents, buffers and packaging according to the project requirements.

Is bulk manufacturing available?

Yes. Research samples, pilot quantities and bulk production can be discussed based on the customer’s development stage and annual demand.

Lot reservation and customer-specific quality-control requirements may also be available.

How should HQD610-100 be stored?

The product should generally be stored at 2–8°C, protected from light and not frozen.

Always follow the storage instructions stated on the product label and lot-specific certificate of analysis.

Is HQD610-100 intended for clinical use?

HQD610-100 is supplied for research use and diagnostic reagent development.

It is not intended for direct administration to humans or animals and is not a finished diagnostic product.

Request a Sample or Bulk Quotation

SHBC supports immunoassay developers from early material screening to pilot production and large-scale reagent manufacturing.

To request an HQD610-100 sample or quotation, please provide:

• Intended assay format

• Target analyte

• Sample matrix

• Required detection range

• Fluorescence-reader excitation and emission channels

• Preferred surface functional group

• Required sample quantity

• Expected annual demand

• Special buffer or packaging requirements

Contact SHBC to evaluate 100 nm Quantum Dot Microspheres HQD610-100 for your fluorescence immunoassay, lateral flow assay or quantitative diagnostic reagent development project.