30nm Carboxyl Red-Fluo Microspheres CFR030-10 0.5%

30nm Carboxyl Red-Fluo Microspheres CFR030-10

CFR030-10 30nm Carboxyl Red-Fluo Microspheres are nanoscale fluorescent polymer particles developed for lateral flow immunoassay research, fluorescent labeling, antibody conjugation, assay optimization, and scale-up reagent manufacturing.

The microspheres have a nominal particle diameter of 30 nm, a carboxyl-functionalized surface, red fluorescence, and a standard solids concentration of 1% w/v. Their small particle size provides a high particle number and large available surface area per unit mass, making them suitable for researchers evaluating nanoscale fluorescent labels in sensitive and quantitative lateral flow systems.

The surface carboxyl groups can be activated using carbodiimide chemistry for covalent immobilization of antibodies, antigens, proteins, peptides, and other biomolecules containing primary amine groups. Carboxyl-modified fluorescent microspheres are widely used as coupling particles because they support stable covalent conjugation through EDC or EDC/NHS activation.

CFR030-10 is supplied for research use, immunoassay development, process optimization, pilot production, and bulk manufacturing of lateral flow reagents.

What Are 30nm Carboxyl Red-Fluo Microspheres?

30nm Carboxyl Red-Fluo Microspheres are fluorescent nanoparticles containing red fluorescent dye within a polymer particle matrix and functional carboxyl groups on the outer surface.

The fluorescent component provides an optical signal that can be detected by a compatible fluorescence reader. The surface carboxyl groups provide reactive sites for covalent conjugation with antibodies or other amine-containing biomolecules.

Unlike passive adsorption-based labels, carboxyl-functionalized microspheres can form stable covalent bonds with biological ligands after activation. This helps assay developers improve conjugate stability and control biomolecule immobilization during lateral flow reagent development.

Fluorescent particles have been used in lateral flow systems for qualitative and quantitative detection, while carboxylated particles provide a convenient surface for protein conjugation.

Product Specifications

The exact excitation and emission wavelengths, particle-size distribution, surface carboxyl content, packaging specification, preservative system, and batch-specific testing data can be provided according to the applicable product specification or Certificate of Analysis.

Key Features of CFR030-10 Red Fluorescent Microspheres

30nm Nanoscale Particle Diameter

The nominal 30 nm particle size provides a high number of fluorescent particles at a given solids concentration.

For a fixed polymer density and mass, reducing particle diameter substantially increases particle number. Smaller particles also provide more total surface area per unit mass, which can be beneficial when optimizing antibody loading and conjugate mobility.

Because the particles are significantly smaller than conventional 100–400 nm lateral flow labels, the final membrane migration, test-line capture efficiency, brightness, background, and antibody loading should be evaluated for the specific assay system.

Red Fluorescence for Instrument-Based Detection

The incorporated red fluorescent signal can be detected using a fluorescence reader configured for the corresponding excitation and emission wavelengths.

Compared with visually interpreted colored labels, fluorescent detection can support:

• Instrument-based signal measurement

• Quantitative or semi-quantitative analysis

• Broader analytical measurement ranges

• Digital result interpretation

• Reduced dependence on subjective visual judgment

• Integration with portable lateral flow readers

Fluorescent lateral flow platforms are commonly developed to improve quantitative detection and analytical sensitivity, although final performance depends on fluorophore brightness, reader optics, conjugate chemistry, membrane properties and assay design.

Carboxyl-Functionalized Surface

CFR030-10 microspheres contain carboxyl groups on the particle surface.

After activation, these groups can react with primary amine groups present in antibodies, proteins and peptides to form stable amide bonds.

Carboxyl-functionalized particles are suitable for covalent conjugation using water-soluble carbodiimide reagents such as EDC. NHS or sulfo-NHS may also be introduced to improve active-ester formation and facilitate protein coupling.

Internally Incorporated Fluorescent Dye

The red fluorescent dye is incorporated within the polymer particle matrix rather than relying only on surface adsorption.

This structure is designed to support:

• Stable fluorescence

• Reduced dye migration during washing

• Consistent optical labeling

• Improved compatibility with antibody conjugation

• Better retention of fluorescence during assay processing

Final fluorescence stability should be validated under the selected buffer, surfactant, membrane and storage conditions.

0.5% Ready-to-Optimize Suspension

The standard 0.5% w/v solids concentration is suitable for laboratory development and formulation studies.

Researchers can dilute the microsphere suspension according to:

• Target antibody loading

• Conjugate dispensing concentration

• Membrane flow rate

• Reader sensitivity

• Test-line signal requirement

• Desired detection range

The optimal working concentration should be established experimentally for each assay.

Why Use 30nm Red Fluorescent Microspheres in Lateral Flow Assays?

The 30 nm particle size is designed for assay developers who need a nanoscale fluorescent label with rapid membrane transport potential and a high particle number.

Small fluorescent nanoparticles may be particularly useful when:

• The membrane has relatively small or restrictive pores

• Rapid conjugate release is required

• High particle-number labeling is preferred

• The assay uses an optical reader with high fluorescence sensitivity

• Researchers need to compare nanoscale labels with conventional microspheres

• Biomolecule loading must be optimized across a large particle population

• Low concentrations of conjugate are being evaluated

Fluorescent nanoparticles around 15 nm have previously been used as lateral flow labels with portable fluorescence readers, demonstrating that nanoscale fluorescent reporters can function in lateral-flow formats. However, particle transport and retention in porous membranes are affected by particle size, particle concentration, membrane structure and buffer conditions.

CFR030-10 should therefore be evaluated as part of the complete LFIA system rather than selected only according to nominal particle diameter.

Main Applications

Fluorescent Lateral Flow Immunoassays

CFR030-10 can be evaluated as a fluorescent reporter particle in sandwich, competitive and indirect lateral flow formats.

Typical development areas include:

• Antigen detection

• Antibody detection

• Infectious-disease research

• Inflammation biomarker research

• Food-safety testing

• Veterinary diagnostic research

• Environmental monitoring

• Agricultural pathogen testing

• Pharmaceutical quality-control research

Quantitative Lateral Flow Detection

The red fluorescent signal can be measured using a compatible optical reader to generate a numerical test-line result.

Potential quantitative outputs include:

• Test-line fluorescence intensity

• Test-to-control signal ratio

• Calibration-curve concentration

• Positive or negative threshold

• Semi-quantitative concentration range

• Time-dependent reaction signals

Antibody and Protein Conjugation

The carboxyl-functionalized surface is suitable for coupling:

• Monoclonal antibodies

• Polyclonal antibodies

• Recombinant antigens

• Enzymes

• Peptides

• Streptavidin

• Amine-modified oligonucleotides

• Other primary-amine-containing ligands

Multiplex Assay Development

Red fluorescent microspheres may be combined with particles having different fluorescence channels to develop multiplex detection systems.

Before constructing a multiplex system, researchers should verify:

• Spectral separation

• Reader filter compatibility

• Signal compensation

• Cross-reactivity

• Particle migration consistency

• Individual test-line capture efficiency

Immunoassay Reagent Manufacturing

CFR030-10 is available for research companies and reagent manufacturers progressing from laboratory validation to pilot and batch production.

Potential use stages include:

• Label screening

• Conjugation process development

• Formula optimization

• Conjugate-pad development

• Pilot strip production

• Stability studies

• Production transfer

• Batch manufacturing

How Do CFR030-10 Microspheres Work in a Fluorescent LFIA?

In a typical sandwich lateral flow immunoassay, CFR030-10 microspheres are covalently conjugated to a detection antibody.

When the sample is added to the test strip:

1. The sample rehydrates the fluorescent microsphere conjugate.

2. The microsphere-labeled antibody binds to the target analyte.

3. The resulting fluorescent particle–antibody–analyte complex migrates through the nitrocellulose membrane.

4. The complex is captured by an immobilized capture antibody at the test line.

5. Additional microsphere conjugate is captured at the control line to confirm proper flow.

6. A fluorescence reader measures the signal intensity at the test and control lines.

7. The fluorescence result is interpreted qualitatively, semi-quantitatively or quantitatively.

The final analytical performance depends on the combined effect of particle brightness, antibody affinity, surface conjugation, membrane selection, running buffer, conjugate release and reader settings.

Recommended Antibody Coupling Principle

The following workflow is a general development reference rather than a fixed manufacturing protocol. Reagent concentration, pH, reaction time and protein loading should be optimized for the selected antibody and assay.

Step 1: Disperse the Microspheres

Mix the CFR030-10 suspension thoroughly before use.

Gentle vortex mixing, manual inversion or controlled low-energy ultrasonication may be used to redisperse settled particles. Excessive sonication should be avoided because it may affect antibodies or destabilize the formulation.

Step 2: Transfer into Activation Buffer

Transfer the required quantity of microspheres into a suitable activation buffer.

A mildly acidic MES-based buffer is commonly evaluated for carbodiimide activation. Buffers containing free primary amines should generally be avoided during the activation stage because they may compete with the target ligand.

Step 3: Activate the Carboxyl Groups

Add freshly prepared EDC, with or without NHS or sulfo-NHS, to activate the surface carboxyl groups.

The activated carboxyl groups form reactive intermediates that can subsequently react with primary amines on the antibody or protein. Carboxyl fluorescent particles from established manufacturers are commonly coupled using EDAC/EDC-based chemistry.

Step 4: Add the Antibody or Protein

After activation, add the selected antibody or other amine-containing ligand.

Parameters requiring optimization include:

• Protein concentration

• Microsphere-to-protein ratio

• Coupling pH

• Reaction time

• Mixing method

• Temperature

• Ionic strength

Step 5: Block Remaining Reactive Sites

After conjugation, quench or block unreacted active sites using an appropriate blocking reagent.

Possible formulation components may include proteins, amino acids or other validated blocking materials. The selected blocker should not interfere with fluorescence or membrane migration.

Step 6: Wash and Resuspend

Remove unbound protein and reaction by-products by an appropriate purification method.

Because 30 nm nanoparticles are difficult to separate using low-speed centrifugation, the purification process may require:

• High-speed or ultracentrifugation

• Tangential-flow filtration

• Membrane filtration

• Size-exclusion chromatography

• Dialysis

• Other validated nanoparticle purification methods

The most appropriate method depends on batch volume, particle stability and production equipment.

Step 7: Evaluate the Conjugate

Recommended evaluation parameters include:

• Particle-size distribution

• Aggregation level

• Fluorescence intensity

• Protein-coupling efficiency

• Residual unbound protein

• Zeta potential

• Membrane migration

• Test-line signal

• Background signal

• Control-line consistency

• Accelerated stability

LFIA Development Considerations

Nitrocellulose Membrane Selection

Membrane pore structure and capillary flow rate affect particle migration, capture efficiency and assay time.

A membrane should be selected by evaluating:

• Migration speed

• Test-line sharpness

• Background fluorescence

• Particle retention

• Non-specific adsorption

• Total assay time

• Compatibility with the selected sample matrix

A membrane that works well with 200 or 300 nm particles may not produce identical results with 30 nm nanoparticles.

Conjugate-Pad Release

The conjugate pad should release the fluorescent microspheres rapidly and reproducibly after sample application.

Release formulations may require optimization of:

• Sugars

• Proteins

• Surfactants

• Polymers

• Salts

• Buffer pH

• Drying conditions

• Conjugate application amount

Incomplete release can reduce sensitivity and increase strip-to-strip variation.

Fluorescent Reader Compatibility

The reader must be compatible with the excitation and emission characteristics of the selected CFR030-10 fluorescence configuration.

Before finalizing the assay, confirm:

• Excitation light source

• Emission filter

• Detector sensitivity

• Exposure or integration time

• Test-line scanning position

• Background subtraction method

• Signal saturation limit

• Calibration algorithm

Exact optical specifications should be confirmed using the applicable CFR030-10 technical data or batch documentation.

Antibody Loading

Increasing antibody loading does not always improve assay sensitivity.

Excessive antibody loading may result in:

• Particle aggregation

• Steric hindrance

• Reduced antigen accessibility

• Slower migration

• Higher non-specific binding

• Increased reagent cost

A protein-loading gradient should be evaluated during process development.

Particle Concentration

The optimum microsphere concentration depends on the reader, membrane and target detection range.

A concentration that is too low may produce weak fluorescence. A concentration that is too high may increase background, slow flow, cause membrane retention or saturate the reader.

Running Buffer

The running buffer influences:

• Antigen–antibody binding

• Conjugate release

• Particle dispersion

• Non-specific adsorption

• Membrane flow

• Test-line intensity

Surfactant type, surfactant concentration, protein blocker, salt concentration and pH should be optimized together.

30nm Versus Larger Fluorescent Microspheres

These are general development tendencies rather than guaranteed assay results. The optimum particle size should be selected through side-by-side strip testing.

Quality Control for Research and Batch Production

For research institutions and diagnostic-reagent manufacturers, particle consistency is important during the transfer from R&D to production.

Recommended batch-control parameters include:

Particle Size

Particle size and distribution influence membrane flow, surface area, antibody loading and conjugate consistency.

Solids Concentration

Consistent solids concentration helps maintain repeatable particle input during coupling and dispensing.

Fluorescence Consistency

Fluorescence intensity should be evaluated between batches using consistent instrument settings.

Surface Carboxyl Content

Carboxyl density affects protein-loading capacity and coupling efficiency.

Dispersion Stability

The suspension should be evaluated for sedimentation, aggregation and recovery after redispersion.

Conjugation Performance

Representative coupling tests can help verify that new batches perform consistently with established reference material.

LFIA Performance

Where appropriate, incoming material may be evaluated in a standardized model strip to compare:

• Test-line intensity

• Control-line intensity

• Background

• Migration time

• Signal ratio

• Coefficient of variation

Advantages for Research Companies and Reagent Manufacturers

CFR030-10 is designed to support both early-stage research and scale-up production.

Key commercial and technical advantages include:

• 30 nm specialized particle-size option

• Red fluorescent optical signal

• Carboxyl surface for covalent conjugation

• Standard 1% solids suspension

• Suitable for LFIA development

• Support for antibody and protein coupling

• Research sample availability

• Pilot-batch supply

• Bulk production capability

• Batch documentation support

• Particle and fluorescence customization

• Packaging customization

• Technical communication during process transfer

Customization Options

Customized fluorescent microsphere specifications can be discussed according to project requirements.

Available customization options may include:

Particle Size Customization

Alternative nanoscale and microscale particle diameters can be developed or supplied for comparative assay testing.

Fluorescence Customization

Fluorescence color, excitation range, emission range and intensity can be evaluated according to reader compatibility.

Surface Functionalization

Available or developable surface chemistries may include:

• Carboxyl

• Amino

• Aldehyde

• Epoxy

• Streptavidin

• Other project-specific functional groups

Solids Concentration

Alternative solids concentrations may be prepared according to coupling and manufacturing requirements.

Packaging

Research, pilot and production packaging can be discussed based on projected usage volume.

OEM and Bulk Manufacturing

OEM, custom labeling, batch supply and long-term manufacturing cooperation are available for qualified research and reagent-production projects.

Storage and Handling

For fluorescent carboxyl microsphere suspensions, the following general handling practices are recommended unless the product-specific COA, SDS or technical specification states otherwise:

• Store refrigerated at approximately 2–8°C

• Protect the suspension from strong light

• Keep the container tightly closed

• Do not freeze unless freeze stability has been validated

• Mix thoroughly before sampling

• Avoid prolonged exposure to intense excitation light

• Use clean, low-binding laboratory materials where possible

• Prevent microbial contamination

• Avoid repeated uncontrolled temperature cycling

Established fluorescent microsphere suppliers commonly recommend refrigerated, light-protected storage, and some specifically warn against prolonged exposure to intense light sources.

Frequently Asked Questions

What is CFR030-10?

CFR030-10 is a 30 nm carboxyl-functionalized red fluorescent microsphere suspension with a standard solids concentration of 1% w/v. It is developed for fluorescent lateral flow immunoassay research, antibody conjugation, assay optimization and reagent manufacturing.

Can CFR030-10 be used in lateral flow assays?

Yes. CFR030-10 is designed for evaluation as a fluorescent reporter label in lateral flow immunoassays. Final compatibility should be confirmed with the selected membrane, antibody pair, sample matrix, conjugate pad and fluorescence reader.

Can antibodies be covalently coupled to the microspheres?

Yes. The surface carboxyl groups can be activated using EDC or EDC/NHS chemistry and then reacted with primary amine groups on antibodies or proteins to form stable amide bonds.

Are 30nm microspheres suitable for quantitative LFIA?

They can be evaluated for quantitative LFIA when used with a compatible fluorescence reader. Quantitative performance depends on fluorescence brightness, antibody affinity, test-strip design, reader calibration and data-processing methods.

Is the red fluorescence visible to the naked eye?

The product should be treated as a fluorescent optical label rather than a conventional visibly colored latex label. Fluorescence performance is evaluated under the appropriate excitation source and through a compatible emission channel.

What excitation and emission wavelengths should be used?

The reader wavelength must match the specific fluorescence configuration of CFR030-10. Confirm the applicable excitation and emission specifications on the technical data sheet, COA or project specification before selecting the reader filters.

What is the recommended antibody-loading amount?

There is no universal loading amount for all antibodies. A gradient experiment should be performed because the optimum protein-to-particle ratio depends on antibody molecular properties, affinity, formulation and target assay performance.

How should 30nm particles be purified after conjugation?

Because 30 nm particles may not sediment efficiently under conventional low-speed centrifugation, methods such as ultracentrifugation, tangential-flow filtration, membrane filtration, dialysis or chromatography may need to be evaluated.

Can the solids concentration be customized?

Alternative solids concentrations can be discussed according to the required conjugation process, dispensing method, production volume and shipping specification.

Are bulk quantities available?

Yes. Research samples, pilot quantities and bulk-production supply can be discussed for research institutions, biotechnology companies and lateral flow reagent manufacturers.

Can you provide batch documentation?

Available documentation may include a Certificate of Analysis, product specification, SDS and batch-related quality information according to the agreed product and supply requirements.

Is CFR030-10 intended for direct clinical use?

CFR030-10 is supplied as a raw material for research, assay development and reagent-manufacturing applications. The finished diagnostic product must be validated and registered by the customer according to the applicable regulatory requirements.

Why Choose SHBC 30nm Carboxyl Red-Fluo Microspheres?

SHBC provides fluorescent microsphere materials for biotechnology research, immunoassay development and reagent manufacturing.

By selecting CFR030-10, customers can access:

• A specialized 30 nm fluorescent nanoparticle size

• Carboxyl-functionalized surface chemistry

• Red fluorescent labeling

• Standardized solids concentration

• Research and scale-up supply

• Customized particle specifications

• OEM and bulk-production support

• Technical communication for conjugation and LFIA development

• Batch-oriented quality-control services

• Long-term material-supply cooperation

Request a Sample or Bulk Quotation

Contact SHBC to request a sample, technical specification, Certificate of Analysis, bulk quotation or customized fluorescent microsphere solution.

Please provide the following project information when making an inquiry:

• Target analyte

• Lateral flow assay format

• Antibody or ligand type

• Required excitation and emission range

• Fluorescence reader model

• Desired particle size

• Required solids concentration

• Estimated research or annual production volume

• Packaging requirements

• Current development challenges

Our technical and manufacturing team will evaluate the project requirements and recommend an appropriate fluorescent microsphere specification for laboratory development, pilot testing or batch production.