160nm Quantum Dot Microspheres HQD610-160 1%

160 nm Quantum Dot Microspheres HQD610-160

SHBC HQD610-160 Quantum Dot Microspheres are high-brightness fluorescent microspheres developed for immunoassay research, quantitative fluorescence detection, lateral flow assay development and bulk diagnostic reagent manufacturing.

The product has a nominal particle size of 160 nm, a solids content of 1%, an excitation wavelength of approximately 360 nm and a fluorescence emission peak centered at approximately 620 nm.

Multiple quantum dots are incorporated into each polymer microsphere to generate a strong orange-red fluorescent signal. The functional microsphere surface provides a practical platform for coupling antibodies, antigens, proteins, peptides, oligonucleotides and other affinity ligands.

HQD610-160 is designed for research institutions, IVD developers, fluorescence reader manufacturers and immunoassay reagent companies that require consistent fluorescent particles from initial material screening through pilot production and commercial-scale manufacturing.

Product Overview

HQD610-160 combines the optical properties of quantum dots with the handling and surface chemistry advantages of functional polymer microspheres.

Individual quantum dots can provide bright fluorescence but may be difficult to separate, wash and process during routine immunoassay production. Incorporating multiple quantum dots into a polymer nanobead creates a larger and more manageable fluorescent labeling particle.

Quantum dot nanobeads have been used in lateral flow immunoassays because the encapsulation of many quantum dots in one particle can increase the fluorescence generated by each captured label. Their larger particle size also makes separation after antibody conjugation more convenient than the separation of individual quantum dots. 60 nm particle size provides a balance among:

• Fluorescence loading capacity

• Available surface area

• Antibody conjugation capacity

• Colloidal stability

• Centrifugal separation

• Membrane migration

• Test-line accumulation

• Quantitative reader sensitivity

HQD610-160 can be evaluated in fluorescence lateral flow assays, quantitative immunoassays, microfluidic detection cartridges, fluorescence biochips, optical biosensors and multiplex biomarker detection systems.

Key Features and Benefits

360 nm Excitation and 620 nm Emission

HQD610-160 is designed for excitation at approximately 360 nm and fluorescence measurement at approximately 620 nm.

This wide separation between the excitation and emission wavelengths can help an optical system distinguish the emitted fluorescence from the excitation light when appropriate filters are used.

The approximately 620 nm orange-red fluorescence channel is suitable for quantitative immunoassay readers and fluorescence strip analyzers.

A compatible reader should generally include:

• A UV excitation source centered near 360 nm

• An excitation filter matched to the effective absorption range

• An emission filter centered near 620 nm

• Appropriate optical bandwidth

• Adjustable exposure time

• Adjustable detector gain

• Background subtraction

• Stable scanning position

• Calibration and data-processing functions

The final optical configuration should be established using the actual excitation and emission spectra of the production lot. Nominal wavelengths alone are not sufficient for final reader validation.

Quantum Dot Encapsulation for Signal Amplification

Multiple quantum dots are incorporated into each HQD610-160 microsphere.

This particle architecture can provide:

• Strong fluorescence output per labeling particle

• Greater signal accumulation at the test line

• Easier separation and washing

• A larger surface for biomolecule immobilization

• Improved handling during reagent preparation

• Better suitability for quantitative detection

• Reduced loss of individual quantum dots

• Potential for single-channel and multiplex assays

Published lateral flow methods describe quantum dot nanobeads containing numerous quantum dots as amplified fluorescent labels for qualitative and quantitative biomarker detection. 60 nm Particle Size

Controlled particle size is important for reproducible conjugation, fluorescence output, membrane migration and test-line formation.

The nominal 160 nm size offers:

• More internal volume for quantum dot loading than smaller nanoparticles

• A relatively large external surface for antibody conjugation

• Strong fluorescence output per captured particle

• Easier centrifugal separation than individual quantum dots

• Lower sedimentation tendency than micron-sized fluorescent beads

• Compatibility with selected lateral flow membranes

• Strong potential for instrument-based quantitative detection

Quantum dot nanobeads used in lateral flow research commonly fall within a broader nanoscale range of approximately 70–200 nm, making 160 nm a practical size for evaluating the balance between fluorescence intensity and flow performance. l Surface for Biomolecule Coupling

HQD610-160 can be supplied with an application-compatible functional surface for biomolecule conjugation.

For a carboxyl-functionalized version, surface carboxyl groups can be activated through EDC/NHS chemistry and covalently coupled with primary amine groups on antibodies, proteins or other ligands.

Compatible biomolecules may include:

• Monoclonal antibodies

• Polyclonal antibodies

• Recombinant proteins

• Antigens

• Peptides

• Enzymes

• Aptamers

• Amine-modified oligonucleotides

• Other amine-containing ligands

Commercial carboxyl quantum dot products similarly use EDC-mediated condensation to couple quantum dots with proteins and modified oligonucleotides. rface functional group of HQD610-160 should be confirmed using the product specification or lot-specific certificate of analysis before establishing a conjugation protocol.

Stable 1% Solids Suspension

HQD610-160 is supplied as an aqueous microsphere suspension with a solids content of 1%.

When expressed as weight per volume, a 1% suspension contains approximately 10 mg of microspheres per milliliter.

The amount required for one conjugation reaction depends on:

• Antibody type

• Antibody molecular weight

• Desired surface coverage

• Microsphere recovery

• Assay format

• Required fluorescence intensity

• Final conjugate concentration

• Test-strip dispensing volume

• Number of tests to be manufactured

The suspension should be mixed thoroughly before sampling to restore a uniform particle concentration.

Bright and Stable Fluorescence

Quantum dots are widely selected for applications requiring bright fluorescence, narrow emission bands and better resistance to photobleaching than many conventional organic dyes.

Commercial Qdot 625 materials are similarly promoted for bright fluorescence, narrow emission, photostability and excitation using UV-to-visible light sources. nce stability of the finished reagent will also depend on:

• Storage temperature

• Buffer pH

• Ionic strength

• Light exposure

• Oxidizing agents

• Reducing agents

• Surfactants

• Preservatives

• Drying temperature

• Residual moisture

• Packaging material

Suitable for Quantitative Detection

The approximately 620 nm signal can be measured by a compatible fluorescence reader.

HQD610-160 may be evaluated in:

• Qualitative fluorescence tests

• Semi-quantitative tests

• Quantitative immunoassays

• Single-analyte detection

• Multiplex biomarker detection

• Laboratory fluorescence systems

• Portable point-of-care readers

• Automated diagnostic cartridges

A calibration curve should be established for every target analyte, sample type and reader configuration.

Lot-Controlled Supply for Reagent Manufacturing

HQD610-160 is developed for customers that require more than small research quantities.

SHBC supports:

• Initial material samples

• Antibody-conjugation experiments

• Assay-development quantities

• Pilot-production batches

• Scale-up verification

• Bulk manufacturing

• Lot reservation

• Customized packaging

• Customer-specific quality specifications

• OEM and ODM projects

Stable control of particle size, solids content, fluorescence properties and surface functionality helps reduce material-related risks when transferring an assay from research to routine manufacturing.

Technical Specifications

The following parameters should be confirmed using the lot-specific specification or certificate of analysis:

• Particle-size tolerance

• Hydrodynamic particle size

• Polydispersity

• Fluorescence bandwidth

• Relative fluorescence intensity

• Surface functional-group density

• Zeta potential

• Dispersion-buffer composition

• Preservative system

• Storage temperature

• Shelf life

Why Choose 160 nm Quantum Dot Microspheres?

Particle size affects fluorescence loading, biomolecule conjugation, steric hindrance, colloidal stability, membrane migration and test-line signal.

The 160 nm size is particularly suitable for assay developers who require a strong fluorescence signal while retaining nanoscale particle behavior.

Potential Benefits of the 160 nm Size

HQD610-160 may provide:

• Strong fluorescence per labeling particle

• High potential biomolecule-loading capacity

• Good accumulation at the test line

• Practical centrifugal separation

• Lower sedimentation than micron-sized microspheres

• Compatibility with selected nitrocellulose membranes

• Strong response from portable fluorescence readers

• Good potential for quantitative assays

• A useful balance between brightness and flow performance

160 nm vs. 100 nm Quantum Dot Microspheres

Compared with a 100 nm microsphere, a 160 nm microsphere generally provides greater particle volume and external surface area.

A 160 nm product may be preferred when the assay requires:

• Higher fluorescence output per particle

• Greater potential antibody-loading capacity

• Stronger test-line accumulation

• Easier centrifugal recovery

• Improved detection with a portable reader

• Lower particle dosage for a comparable fluorescence signal

A 100 nm product may be preferred when the assay requires:

• Faster membrane migration

• Better passage through smaller membrane pores

• Reduced steric hindrance

• Lower risk of flow retardation

• Better performance in viscous samples

The final choice should be based on side-by-side testing under the intended assay conditions.

160 nm vs. 200 nm Quantum Dot Microspheres

Compared with a 200 nm product, a 160 nm microsphere may provide:

• Faster migration

• Lower risk of membrane retention

• Better colloidal stability

• Reduced sedimentation

• Easier release from the conjugate pad

• Better compatibility with relatively small-pore membranes

A 200 nm product may provide stronger fluorescence per particle but can require more careful optimization of membrane pore structure, surfactant concentration and sample viscosity.

When to Evaluate HQD610-160

HQD610-160 should be considered when:

• A colloidal gold test does not provide sufficient quantitative sensitivity

• A conventional fluorescent latex particle does not generate enough signal

• Individual quantum dots are difficult to wash and recover

• The reader uses a UV excitation source near 360 nm

• An orange-red emission channel near 620 nm is required

• Quantitative fluorescence detection is planned

• A multiplex fluorescence panel is being developed

• The project requires pilot and bulk material supply

How HQD610-160 Works in Immunoassays

HQD610-160 microspheres are conjugated with a recognition molecule such as an antibody, antigen, protein or aptamer.

When the conjugated microspheres contact the sample, the recognition molecule binds to the target analyte. The resulting complex is then captured at a test line, microplate surface, microfluidic channel or another solid-phase detection zone.

Under approximately 360 nm excitation, the accumulated microspheres emit fluorescence centered near 620 nm. A compatible fluorescence reader measures the signal and converts it into a qualitative, semi-quantitative or quantitative result.

Typical Sandwich Lateral Flow Assay

A sandwich lateral flow immunoassay may include:

1. HQD610-160 conjugated with a detection antibody

2. Target analyte in the sample

3. Capture antibody immobilized at the test line

4. Control reagent immobilized at the control line

5. A conjugate pad containing the dried fluorescent conjugate

6. A running buffer supporting particle release and migration

7. A fluorescence reader configured for the 360/620 nm channel

8. A calibration curve for quantitative interpretation

Typical Competitive Assay

For a small-molecule analyte, a competitive assay may include:

1. HQD610-160 conjugated with an antibody or target analogue

2. Immobilized competing antigen at the test line

3. Target molecules in the sample

4. An inverse relationship between analyte concentration and test-line signal

Competitive formats may be evaluated for:

• Mycotoxins

• Antibiotics

• Pesticides

• Veterinary drug residues

• Hormones

• Other small molecules

Recommended Applications

Fluorescence Lateral Flow Immunoassay

HQD610-160 can be evaluated as a fluorescent reporter in lateral flow immunoassays.

Potential application fields include:

• Infectious disease testing

• Inflammation biomarker detection

• Cardiac marker detection

• Hormone testing

• Tumor-marker research

• Veterinary diagnostics

• Food safety testing

• Mycotoxin detection

• Antibiotic-residue testing

• Pesticide-residue testing

• Environmental monitoring

• Agricultural testing

Quantum dot nanobead-based lateral flow systems have been used for qualitative and quantitative disease biomarker detection under UV excitation and fluorescence-reader measurement. ive Fluorescence Immunoassay

HQD610-160 may be used in instrument-based immunoassays requiring quantitative measurement.

Potential formats include:

• Sandwich fluorescence immunoassays

• Competitive fluorescence immunoassays

• Fluorescence-linked immunosorbent assays

• Dry fluorescence test strips

• Cartridge-based fluorescence assays

• Automated immunoassay systems

• Portable point-of-care readers

• Microplate fluorescence assays

A standard curve should be established for every target analyte and sample matrix.

Multiplex Biomarker Detection

Quantum dots with different emission wavelengths may be excited using a common or overlapping excitation source.

HQD610-160 can serve as the approximately 620 nm channel in a multiplex detection panel.

Multiplex assay development requires optimization of:

• Fluorescence channel separation

• Excitation source

• Emission filters

• Optical bandwidth

• Particle concentrations

• Antibody combinations

• Capture-zone positions

• Cross-reactivity

• Signal compensation

• Reader gain

• Data-processing algorithms

Commercial quantum dot product families are available in multiple emission colors and can often be efficiently excited using a common UV-to-visible excitation source. and Biosensors

HQD610-160 may be evaluated in:

• Fluorescence biochips

• Optical biosensors

• Microarray systems

• Disposable diagnostic cartridges

• Portable fluorescence analyzers

• Automated fluorescence platforms

The particle must be tested for compatibility with the chip surface, fluid pathway, optical system and signal-processing method.

Microfluidic Platforms

Potential microfluidic applications include:

• Lab-on-a-chip immunoassays

• Microfluidic diagnostic cartridges

• Automated sample-processing systems

• Miniaturized fluorescence detection

• Multiplex microchannel assays

Compatibility with channel dimensions, pumps, valves, filters and detector geometry should be verified.

Biomolecule Labeling and Tracing

The functional surface can be used to immobilize proteins and other ligands for fluorescence labeling and tracing research.

For cell-related applications, researchers should independently evaluate:

• Cytotoxicity

• Nonspecific uptake

• Cellular internalization

• Surface-charge effects

• Biological compatibility

• Signal stability

• Washing requirements

Antibody and Protein Conjugation

Carboxyl Coupling Principle

For a carboxyl-functionalized HQD610-160 product, EDC can be used to activate surface carboxyl groups. NHS is commonly added to form a more stable active intermediate.

Primary amine groups on an antibody or protein then react with the activated carboxyl surface to form stable covalent amide bonds.

Commercial quantum dot products and protocols use EDC or EDC/NHS chemistry to couple carboxyl-functionalized particles with proteins and other amine-containing ligands. oupling Workflow

A general development workflow includes:

1. Mix the HQD610-160 suspension thoroughly.

2. Transfer the required microsphere quantity into a low-binding tube.

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

4. Prepare fresh EDC and NHS solutions.

5. Add EDC and NHS to activate the carboxyl groups.

6. Incubate under controlled mixing conditions.

7. Remove excess activation reagents.

8. Add the antibody or protein.

9. Incubate under the selected coupling conditions.

10. Add a suitable blocking reagent.

11. Wash the conjugated microspheres.

12. Resuspend the conjugate in an optimized storage buffer.

13. Measure particle recovery.

14. Confirm fluorescence retention.

15. Evaluate functional binding in the intended assay.

This is a development framework rather than a fixed production formula.

Variables Requiring Optimization

Important coupling variables include:

• Microsphere concentration

• EDC concentration

• NHS concentration

• Activation-buffer composition

• Activation pH

• Activation time

• Antibody-to-particle ratio

• Coupling-buffer composition

• Coupling pH

• Coupling time

• Reaction temperature

• Mixing speed

• Blocking reagent

• Washing method

• Centrifugation speed

• Final storage buffer

• Surfactant concentration

• Preservative system

Avoid Excessive Antibody Loading

Higher antibody loading does not always improve assay performance.

Excessive surface coverage may cause:

• Steric hindrance

• Reduced antigen accessibility

• Microsphere aggregation

• Increased nonspecific binding

• Slower membrane migration

• Poor conjugate-pad release

• Increased raw-material cost

• Lower production reproducibility

Several antibody-to-particle ratios should therefore be compared during development.

Evaluation After Conjugation

Recommended evaluation parameters include:

• Particle recovery

• Fluorescence retention

• Hydrodynamic particle size

• Polydispersity

• Visible aggregation

• Redispersion performance

• Antibody-binding activity

• Nonspecific binding

• Test-line fluorescence

• Background fluorescence

• Control-line performance

• Conjugate storage stability

Recommended Immunoassay Development Workflow

Step 1: Confirm the Material Specification

Before conjugation, confirm:

• Catalog number

• Nominal particle size

• Particle-size tolerance

• Solids content

• Excitation wavelength

• Emission wavelength

• Surface functional group

• Dispersion buffer

• Initial fluorescence intensity

• Storage requirements

Step 2: Match the Fluorescence Reader

Confirm that the reader provides:

• UV excitation near 360 nm

• A suitable excitation filter

• An emission filter near 620 nm

• Sufficient detector sensitivity

• Adjustable gain

• Adjustable exposure time

• Stable scanning repeatability

• Background subtraction

• Calibration functions

The final reader configuration should be verified using the actual microsphere lot.

Step 3: Screen Antibody-Loading Levels

Evaluate several antibody-to-microsphere ratios.

For every formulation, record:

• Coupling recovery

• Particle size after coupling

• Fluorescence retention

• Test-line signal

• Background signal

• Migration time

• Reproducibility

• Stability

Step 4: Optimize Activation Conditions

Screen:

• EDC dosage

• NHS dosage

• Activation time

• Activation pH

• Coupling pH

• Reaction temperature

• Mixing intensity

The strongest chemical activation does not necessarily produce the most active antibody conjugate.

Step 5: Optimize Blocking and Storage Buffers

Potential formulation components include:

• Bovine serum albumin

• Casein

• Inert proteins

• Glycine

• Ethanolamine

• Sugars

• Polyols

• Salts

• Surfactants

• Preservatives

The selected formulation should maintain fluorescence, colloidal stability and antibody activity.

Step 6: Screen Conjugate Pads

Evaluate:

• Glass-fiber pads

• Polyester pads

• Pad pretreatment

• Conjugate concentration

• Dispensing volume

• Drying temperature

• Drying time

• Sugar stabilizers

• Protein blockers

• Surfactants

Step 7: Screen Nitrocellulose Membranes

Compare membranes with different:

• Capillary-flow rates

• Pore structures

• Protein-binding capacities

• Thicknesses

• Surface treatments

A membrane that produces a strong signal but inconsistent migration may not be suitable for commercial production.

Step 8: Optimize the Running Buffer

Evaluate:

• pH

• Ionic strength

• Protein blockers

• Surfactants

• Chelating agents

• Viscosity modifiers

• Heterophilic-antibody blockers

• Antimicrobial preservatives

Step 9: Optimize Microsphere Dosage

Excessive microsphere dosage may increase raw fluorescence but can also increase:

• Background

• Aggregation

• Membrane retention

• Migration time

• Hook-effect risk

• Production cost

Select the lowest particle dosage that meets the required analytical performance.

Step 10: Validate the Sample Matrix

Evaluate:

• Negative samples

• Low-positive samples

• High-positive samples

• Hemolytic samples

• Lipemic samples

• Icteric samples

• High-viscosity samples

• Cross-reactive samples

• Common interfering substances

Step 11: Perform Stability Testing

Recommended studies include:

• Liquid conjugate stability

• Dried conjugate stability

• Accelerated strip stability

• Real-time strip stability

• Open-pouch stability

• Freeze-thaw evaluation when relevant

• Temperature-transport simulation

• Lot-to-lot reproducibility

Factors Affecting Assay Performance

HQD610-160 provides a fluorescent signal platform, but it does not independently determine the final detection limit.

Final assay performance also depends on:

• Antibody affinity

• Antibody specificity

• Epitope accessibility

• Antibody orientation

• Antibody-loading density

• Microsphere aggregation

• Particle dosage

• Membrane selection

• Capture-antibody concentration

• Running-buffer composition

• Sample viscosity

• Sample autofluorescence

• Nonspecific adsorption

• Reader sensitivity

• Filter matching

• Strip assembly

• Reaction time

• Environmental temperature

Weak Test-Line Signal

Possible causes include:

• Insufficient antibody loading

• Low-affinity antibody

• Incorrect excitation wavelength

• Incorrect emission filter

• Insufficient microsphere dosage

• Poor capture-antibody activity

• Excessively fast membrane flow

• Incomplete conjugate release

• Fluorescence loss during coupling

• Incorrect reader gain

High Background Fluorescence

Possible causes include:

• Excessive microsphere dosage

• Excessive antibody loading

• Inadequate blocking

• High nonspecific adsorption

• Microsphere aggregation

• Incompatible membrane

• Incorrect surfactant concentration

• Reader gain set too high

• Sample autofluorescence

• Insufficient washing during conjugation

Slow or Incomplete Migration

Possible causes include:

• Particle aggregation

• High conjugate concentration

• Small membrane pores

• High sample viscosity

• Insufficient surfactant

• Poor conjugate-pad release

• Excessive protein concentration

• Incompatible buffer ionic strength

Low Conjugation Recovery

Possible causes include:

• Inappropriate centrifugation speed

• Incomplete particle resuspension

• Adhesion to the reaction tube

• Particle loss during washing

• Aggregation during activation

• Incorrect buffer composition

• Excessive reaction time

Poor Lot-to-Lot Reproducibility

Possible causes include:

• Inconsistent particle mixing

• Variable EDC/NHS activity

• Variation in antibody quality

• Uncontrolled reaction temperature

• Inconsistent reaction time

• Variation in washing recovery

• Changes in membrane batches

• Changes in pad materials

• Reader-calibration differences

Quantum Dot Microspheres vs. Other Signal Labels

No signal label is optimal for every application.

The final label should be selected according to:

• Required detection limit

• Quantitative range

• Sample matrix

• Assay format

• Reader platform

• Multiplexing requirements

• Manufacturing cost

• Required shelf life

• Production process

Quality Control for Batch Production

For commercial immunoassay manufacturing, lot consistency is as important as the fluorescence intensity of the initial evaluation sample.

Recommended quality-control parameters include:

• Mean particle size

• Particle-size distribution

• Polydispersity

• Solids content

• Excitation spectrum

• Fluorescence emission peak

• Relative fluorescence intensity

• Fluorescence spectrum width

• Surface functional-group consistency

• Zeta potential

• Appearance

• Dispersion stability

• Redispersion performance

• Biomolecule-coupling performance

• Functional immunoassay performance

• Storage stability

• Microbial control when required

Recommended Incoming Inspection

Reagent manufacturers should consider testing each incoming lot for:

1. Appearance and dispersion

2. Solids content

3. Particle size

4. Particle-size distribution

5. Fluorescence intensity

6. Emission peak

7. Conjugation recovery

8. Test-line performance

9. Background fluorescence

10. Migration time

11. Comparison with a qualified reference lot

Reference-Lot Strategy

Customers developing commercial reagents should retain a qualified reference lot.

Each new lot can then be compared using:

• The same antibody

• The same antibody-loading level

• The same coupling protocol

• The same blocking buffer

• The same membrane type

• The same running buffer

• The same fluorescence reader

• The same positive and negative controls

This strategy helps distinguish microsphere-related variation from changes in antibodies, membranes, buffers or reader calibration.

Scale-Up Verification

Before moving from laboratory conjugation to large-scale production, verify:

• Mixing uniformity

• Activation-reagent addition sequence

• Reaction temperature distribution

• Reaction time

• Particle recovery

• Washing efficiency

• Final concentration adjustment

• Filling accuracy

• Conjugate stability

• Functional assay performance

A laboratory formula should not be transferred directly to a larger reactor without process verification.

Customization and Bulk Manufacturing

SHBC supports customized quantum dot microspheres for different immunoassay platforms.

Potential customization options include:

• Different particle sizes

• Alternative excitation wavelengths

• Alternative emission wavelengths

• Carboxyl-functionalized surfaces

• Amine-functionalized surfaces

• Streptavidin-functionalized surfaces

• Customized solids content

• Customized dispersion buffer

• Customized preservative

• Low-nonspecific-binding surface treatment

• Customized packaging

• Pilot-batch manufacturing

• Bulk manufacturing

• Lot reservation

• OEM and ODM services

Information Required for Product Selection

To recommend an appropriate microsphere, please provide:

• Target analyte

• Intended assay format

• Sandwich or competitive format

• Sample matrix

• Required detection limit

• Required quantitative range

• Fluorescence-reader model

• Excitation wavelength

• Emission filter

• Preferred surface chemistry

• Required sample quantity

• Estimated annual demand

• Packaging requirements

• Special quality-control requirements

Support from Research to Production

Material screening

Small quantities for comparing particle sizes, fluorescence channels and surface chemistries.

Conjugation development

Materials for antibody-loading, activation, blocking and storage-buffer optimization.

Assay development

Materials for membrane screening, particle-dosage optimization and reader configuration.

Pilot production

Larger quantities for process transfer, stability studies and validation.

Bulk manufacturing

Lot-controlled material supply for routine immunoassay reagent manufacturing.

Storage and Handling

Recommended practices include:

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

• 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 contaminating the original suspension.

• Avoid strong acids and strong alkalis.

• Avoid incompatible organic solvents.

• Avoid prolonged high-power sonication.

• Close the bottle immediately after use.

• Follow the lot-specific expiration date.

Commercial carboxyl Qdot 625 materials are also commonly stored under refrigerated conditions and protected from light. ion occurs during storage, gently invert the container, apply low-speed vortex mixing or use brief mild sonication until the suspension becomes uniform.

Sedimentation alone does not necessarily indicate product failure. Confirm that the microspheres can be fully redispersed and that particle size and fluorescence remain within specification.

Frequently Asked Questions

What is HQD610-160?

HQD610-160 is a quantum dot-loaded fluorescent microsphere suspension with a nominal particle size of 160 nm, a solids content of 1%, an excitation wavelength of approximately 360 nm and an emission wavelength of approximately 620 nm.

It is developed for immunoassay research, fluorescence lateral flow development and bulk diagnostic reagent production.

What fluorescence color does HQD610-160 produce?

HQD610-160 produces an orange-red fluorescent signal centered at approximately 620 nm.

The observed color may vary according to the excitation source, optical filter and observation conditions.

What excitation source is recommended?

A UV excitation source centered near 360 nm is recommended as the initial configuration.

The final excitation source and filter should be selected using the actual excitation spectrum and the intended fluorescence reader.

What emission filter is recommended?

An emission filter centered near 620 nm can be used as an initial configuration.

The filter bandwidth should be optimized according to the actual emission spectrum, detector sensitivity and background fluorescence.

What does 160 nm mean?

It refers to the nominal particle diameter of HQD610-160.

The lot-specific particle-size range and analytical method should be confirmed in the product specification or certificate of analysis.

What does 1% solids content mean?

A 1% weight-per-volume suspension contains approximately 10 mg of microspheres per milliliter.

The actual working concentration should be determined according to the conjugation and assay protocol.

Why choose 160 nm quantum dot microspheres?

The 160 nm size provides a balance among fluorescence loading, biomolecule-coupling capacity, centrifugal recovery, dispersion stability and membrane migration.

It may provide a stronger per-particle signal than smaller microspheres while maintaining better flow performance than larger particles.

Can HQD610-160 be used in lateral flow assays?

Yes. HQD610-160 can be evaluated as a fluorescent reporter in lateral flow immunoassays.

The conjugate pad, nitrocellulose membrane, running buffer, microsphere dosage and reader settings must be optimized for the intended test.

Is HQD610-160 suitable for quantitative detection?

Yes. A compatible fluorescence reader can measure the approximately 620 nm signal and convert it into quantitative results using a calibration curve.

How are antibodies coupled to HQD610-160?

For a carboxyl-functionalized version, antibodies can be covalently coupled through EDC/NHS chemistry.

The activation conditions, antibody dosage, coupling pH and reaction time should be optimized for each antibody.

Can HQD610-160 be used in competitive assays?

Yes. HQD610-160 can be evaluated in competitive immunoassays for small molecules such as toxins, antibiotics, pesticides, veterinary drug residues and hormones.

Can HQD610-160 be used for multiplex detection?

Yes. HQD610-160 can serve as the approximately 620 nm fluorescence channel in a multiplex system.

Other fluorescent particle populations can be combined when the reader provides sufficient spectral separation.

Does HQD610-160 always provide higher sensitivity than colloidal gold?

No signal label automatically guarantees a lower detection limit.

Quantum dot microspheres provide a strong instrument-readable signal, but final sensitivity also depends on antibody quality, conjugation, membrane selection, sample matrix, buffer formulation and reader performance.

Why is my test-line signal weak?

Possible causes include insufficient antibody loading, low antibody affinity, incorrect optical settings, low microsphere dosage, poor conjugate release or unsuitable membrane flow.

Each component should be evaluated systematically.

Why is the background fluorescence high?

Possible causes include excessive microsphere dosage, insufficient blocking, particle aggregation, nonspecific adsorption, sample autofluorescence or excessive reader gain.

Can the solids content be customized?

Customized concentrations may be available depending on the required quantity and project specification.

Is bulk supply available?

Yes. SHBC supports research samples, pilot quantities, bulk manufacturing, lot reservation and customized packaging.

Is HQD610-160 a finished diagnostic reagent?

No. HQD610-160 is a raw material supplied for research use and diagnostic reagent development. It is not a finished diagnostic product.

Request a Sample or Bulk Quotation

SHBC supplies HQD610-160 Quantum Dot Microspheres for immunoassay research, quantitative fluorescence detection, lateral flow assay development and batch reagent manufacturing.

To request a sample, technical consultation or bulk quotation, please provide:

• Target analyte

• Sample matrix

• Assay format

• Required detection limit

• Required quantitative range

• Fluorescence-reader specifications

• Excitation source

• Emission filter

• Preferred surface chemistry

• Required quantity

• Estimated annual demand

• Packaging requirements

• Special quality-control requirements

Contact SHBC to evaluate HQD610-160 for your fluorescence lateral flow assay, quantitative immunoassay, biosensor or multiplex diagnostic reagent project.