20um Streptavidin Microspheres SAPS20UM-10 1%

20µm Streptavidin Microspheres for Biological Research

SHBC SAPS20UM-10 Streptavidin Microspheres are 20µm surface-functionalized microspheres developed for the immobilization and capture of biotinylated antibodies, antigens, proteins, peptides, enzymes, receptors, oligonucleotides, DNA, RNA, aptamers, and other biotin-labeled molecules.

The product is supplied as a 1% solids suspension and is designed for biological research, bead-based immunoassay development, affinity interaction studies, nucleic acid capture, microscopy, microfluidics, cell–particle interaction research, particle-based biosensors, and research reagent manufacturing.

The 20µm particle diameter provides a large individual microsphere surface and a clearly visible micron-sized particle population. Compared with smaller microspheres, the particles can be easier to observe by microscopy, identify in particle-based analytical systems, and recover using an appropriately validated separation method.

Shanghai SanYu Biotechnology Co., Ltd. supports research sample evaluation, pilot-scale development, repeated manufacturing, OEM projects, private-label cooperation, and bulk supply for biotechnology companies, universities, research institutes, reagent manufacturers, instrument developers, and biological research organizations.

Quick Product Answer

SAPS20UM-10 is a 20µm streptavidin-coated microsphere suspension supplied at 1% solids. Its streptavidin-functional surface captures biotinylated biomolecules for biological assays, antibody and protein immobilization, nucleic acid capture, microscopy, cell-interaction studies, affinity research, and particle-based detection-system development.

Product Highlights

• Product name: 20µm Streptavidin Microspheres

• Catalog number: SAPS20UM-10

• Brand: SHBC

• Manufacturer: Shanghai SanYu Biotechnology Co., Ltd.

• Nominal particle diameter: 20µm

• Surface modification: Streptavidin

• Solids content: 1%

• Binding principle: Streptavidin–biotin affinity

• Physical form: Aqueous microsphere suspension

• Primary application: Biological research and bead-based assay development

• Supply capability: Samples, pilot batches, and bulk production

• Customization: Available according to technical feasibility

• Intended use: Research use only

What Are SAPS20UM-10 Streptavidin Microspheres?

SAPS20UM-10 consists of 20µm microspheres with streptavidin immobilized on the particle surface.

The streptavidin coating provides binding sites for biotinylated molecules. A biotinylated antibody, protein, peptide, nucleic acid probe, receptor, ligand, or other biomolecule can be attached to the microsphere without requiring direct carbodiimide activation of the particle surface by the end user.

After the capture molecule has been immobilized, the prepared microspheres can function as a solid phase for:

• Target capture

• Biomolecule immobilization

• Antibody screening

• Protein interaction analysis

• Nucleic acid hybridization

• Cell-surface binding studies

• Microscopy-based assays

• Particle-based biosensors

• Microfluidic research

• Agglutination research

• Bead-based immunoassays

• Affinity separation studies

Potential biotinylated capture molecules include:

• Monoclonal antibodies

• Polyclonal antibodies

• Recombinant antibodies

• Antibody fragments

• Antigens

• Recombinant proteins

• Peptides

• Enzymes

• Receptors

• Lectins

• Growth factors

• Oligonucleotide probes

• DNA probes

• RNA probes

• PCR products

• Aptamers

• Biotinylated small molecules

The 20µm particle diameter is significantly larger than the particle sizes commonly used for high-particle-number immunoassays. This gives each individual microsphere a relatively large physical surface but results in fewer particles per unit mass than smaller microspheres of the same material.

The product is therefore particularly suitable when the research priority includes:

• Large surface area per individual particle

• Direct microscopic observation

• Clear particle identification

• Cell-size-range particle modeling

• Individual-particle analysis

• Controlled particle manipulation

• Microfluidic transport studies

• Easy visual confirmation of recovery

• Size-coded particle systems

SAPS20UM-10 is supplied as a research raw material. It should not automatically be represented as a finished diagnostic reagent, certified particle standard, absolute counting bead, magnetic separation product, or internally fluorescent microsphere unless those functions are specifically included in the final specification.

SAPS20UM-10 Technical Specifications

The following parameters should be confirmed using the final product specification or lot-specific Certificate of Analysis:

• Particle material

• Mean particle diameter

• Particle-size range

• Particle-size distribution

• Particle-size coefficient of variation

• Particle morphology

• Particle density

• Streptavidin coating level

• Biotin-binding capacity

• Particle number concentration

• Suspension buffer

• Buffer pH

• Stabilizer or surfactant

• Preservative

• Recommended separation conditions

• Package size

• Shelf life

• Storage conditions

Biotin-binding capacity should be reported together with:

• The biotinylated test probe

• Molecular weight of the probe

• Number of biotin groups

• Binding buffer

• Incubation conditions

• Washing procedure

• Detection method

• Calculation basis

• Lot-specific result

The 1% solids value alone cannot determine the number of particles per milliliter or the amount of biotinylated ligand that can be immobilized.

How Streptavidin–Biotin Binding Works

Streptavidin is a biotin-binding protein that enables stable non-covalent attachment of biotinylated molecules to the microsphere surface.

When a biotinylated ligand is mixed with SAPS20UM-10, the biotin group binds to available streptavidin sites on the particle.

The general structure can be represented as:

Microsphere Surface – Streptavidin – Biotin – Capture Molecule

For an antibody-based sandwich assay, the structure may be:

Microsphere – Streptavidin – Biotinylated Capture Antibody – Target Antigen – Detection Antibody

If the detection antibody carries a fluorescent, enzymatic, colorimetric, chemiluminescent, or other measurable label, the amount of target associated with the particles can be evaluated using a compatible detection method.

Advantages of Streptavidin–Biotin Immobilization

• Direct EDC/NHS activation is normally unnecessary when loading biotinylated ligands.

• One microsphere platform can be used with many different biotinylated molecules.

• Antibodies, proteins, peptides, oligonucleotides, DNA, RNA and aptamers can be immobilized.

• Ligand loading can be performed under relatively mild aqueous conditions.

• Capture molecules can be changed without redesigning the base microsphere.

• The platform supports modular assay development.

• Ligand loading can be optimized separately from target detection.

• The microspheres can be used with different reporter systems.

• The platform may support single-target and multiplex research.

Factors Affecting Binding Performance

Final ligand loading and assay performance can be affected by:

• Streptavidin coating density

• Streptavidin activity

• Biotinylation level

• Location of biotin groups

• Biotin accessibility

• Spacer length

• Ligand molecular size

• Ligand purity

• Ligand aggregation

• Surface crowding

• Buffer composition

• Salt concentration

• Incubation time

• Incubation temperature

• Mixing method

• Particle settling

Free biotin and unreacted biotinylated reagents can compete with the intended capture molecule for available streptavidin-binding sites. Removal of free biotin or excess biotinylated primer may therefore be important before ligand immobilization.

Why Choose 20µm Streptavidin Microspheres?

Large Surface per Individual Microsphere

A 20µm microsphere provides a larger physical surface per individual particle than 10µm, 5µm, 3µm, or 1µm particles.

This may be useful when:

• A large amount of capture molecule is required on each individual particle

• Strong signal generation per particle is desired

• Individual particles will be observed by microscopy

• Particle-by-particle analysis is required

• A cell-size-range synthetic model is needed

• Surface patterning or localized binding will be investigated

A larger particle does not necessarily provide a higher total surface area per milligram. Smaller particles generally provide a greater number of particles and more collective surface area at the same mass concentration.

Easy Microscopic Observation

The 20µm size makes individual particles comparatively easy to observe using suitable bright-field, phase-contrast, fluorescence, or confocal microscopy.

Microscopy may support:

• Particle morphology evaluation

• Aggregate detection

• Ligand-binding visualization

• Cell–particle interaction studies

• Surface fluorescence analysis

• Particle localization

• Microfluidic tracking

• Particle recovery confirmation

Strong Particle Identification

Large microspheres can be clearly differentiated from small debris and many background particles in imaging, microfluidic, particle-counting, and flow-based analytical systems.

Suitable for Cell-Size-Range Research

The 20µm diameter is within the broad size range of many eukaryotic cells and cell-sized biological structures.

SAPS20UM-10 may be evaluated for:

• Synthetic cell-model research

• Cell-sized particle transport

• Particle–cell contact studies

• Phagocytosis or uptake research

• Cell-surface receptor interaction

• Mechanical handling in microfluidic systems

• Imaging-system development

Synthetic microspheres do not reproduce the complete optical, mechanical, chemical, or biological properties of living cells. Suitability as a cell model must be validated for each project.

Convenient Recovery and Manipulation

Large particles may be comparatively easy to recover by an optimized centrifugation, filtration, or controlled sedimentation method.

The most appropriate method depends on:

• Particle density

• Particle material

• Processing volume

• Centrifugal force

• Centrifugation time

• Filter pore size

• Tube geometry

• Buffer viscosity

• Surfactant concentration

• Required recovery rate

Suitable for Size-Coded Assays

The 20µm population may be combined with smaller microsphere populations in research systems that distinguish particles by size.

Size-based coding may be useful in:

• Multiplex assays

• Multi-analyte research

• Process controls

• Imaging-based assays

• Microfluidic sorting

• Particle-tracking experiments

Key Features and Benefits

20µm Nominal Particle Diameter

The large microsphere size supports direct observation, individual-particle analysis, size-based identification, biological modeling, and particle manipulation.

Streptavidin-Functional Surface

The surface captures biotinylated antibodies, antigens, proteins, peptides, enzymes, oligonucleotides, DNA, RNA, aptamers, receptors, and other biotin-containing molecules.

1% Solids Suspension

SAPS20UM-10 is supplied at 1% solids and can be diluted according to the required particle number, reaction volume, binding capacity, and detection method.

Simple Capture-Ligand Immobilization

Biotinylated capture molecules can be attached without direct chemical activation of the microsphere surface by the end user.

Large Surface per Particle

Each 20µm microsphere provides a comparatively large physical surface for ligand immobilization and signal generation.

Suitable for Multiple Detection Platforms

The particles may be evaluated with:

• Optical microscopy

• Fluorescence microscopy

• Confocal microscopy

• Flow cytometry

• Imaging flow cytometry

• Microfluidic systems

• Plate-based assays

• Particle-counting systems

• Colorimetric detection

• Fluorescent detection

Modular Biological Assay Platform

The same particle platform can be used with different biotinylated capture molecules.

Bulk Production Capability

SHBC supports samples, pilot batches, repeated production, OEM cooperation, private-label projects, and bulk supply.

Custom Development Options

Particle size, streptavidin coating level, binding capacity, concentration, buffer, preservative, fluorescent coding, color coding, packaging, and quality specifications may be discussed for qualified projects.

Biological Research Applications

Bead-Based Immunoassay Development

SAPS20UM-10 may be used as the solid phase in sandwich, indirect, competitive, or agglutination-based research assays.

A sandwich assay may include:

1. Immobilization of a biotinylated capture antibody.

2. Blocking of unoccupied surfaces.

3. Incubation with the target sample.

4. Capture of the target analyte.

5. Addition of a labeled detection antibody.

6. Removal of unbound reagents.

7. Detection of the particle-associated signal.

Potential research targets include:

• Antibodies

• Antigens

• Cytokines

• Hormones

• Growth factors

• Enzymes

• Biomarkers

• Pathogen-associated proteins

• Food-safety analytes

• Environmental targets

• Veterinary research targets

• Research compounds

Competitive Binding Assays

Competitive assay formats may be evaluated for:

• Small molecules

• Haptens

• Drugs

• Toxins

• Peptides

• Hormones

• Metabolites

• Targets with limited binding sites

The relationship between target concentration and measured signal depends on the assay design.

Antibody Immobilization and Screening

Biotinylated antibodies may be attached for:

• Antigen detection

• Antibody screening

• Hybridoma screening

• Antibody specificity studies

• Cross-reactivity evaluation

• Affinity comparison

• Capture-antibody selection

• Assay feasibility testing

Protein and Peptide Interaction Research

Biotinylated proteins or peptides may be immobilized to investigate:

• Antibody–antigen interactions

• Protein–protein interactions

• Receptor–ligand binding

• Epitope recognition

• Enzyme–substrate interactions

• Inhibitor screening

• Drug-candidate binding

• Protein-affinity comparison

Nucleic Acid Capture

Biotinylated oligonucleotides, DNA, RNA, PCR products, and aptamers may be attached to SAPS20UM-10.

Potential applications include:

• Sequence-specific capture

• Hybridization assay development

• PCR-product capture

• Genotyping research

• Mutation-detection research

• Aptamer-based detection

• DNA–protein interaction studies

• RNA-binding research

• Molecular assay development

Cell–Particle Interaction Research

When functionalized with a suitable biotinylated antibody, ligand, receptor, lectin, or peptide, the particles may be evaluated for interaction with cells.

Potential research directions include:

• Cell-surface receptor recognition

• Cell adhesion

• Ligand-mediated cell binding

• Immune-cell interaction

• Particle uptake

• Phagocytosis

• Cellular imaging

• Cell sorting research

• Synthetic antigen-presenting particle research

Important variables include:

• Capture-ligand density

• Particle-to-cell ratio

• Cell concentration

• Incubation time

• Temperature

• Mixing method

• Washing conditions

• Cell viability

• Particle aggregation

• Non-specific attachment

Microscopy and Imaging

The 20µm particles may support:

• Bright-field imaging

• Fluorescence imaging

• Confocal microscopy

• High-content imaging

• Particle localization

• Cell–particle interaction imaging

• Surface fluorescence analysis

• Imaging-based assay development

Microfluidic Research

SAPS20UM-10 may be evaluated in:

• Particle transport studies

• Microchannel flow research

• Size-based separation

• Particle trapping

• Hydrodynamic focusing

• Imaging in microfluidic devices

• Cell-sized particle manipulation

• Device-performance testing

Confirm that the microchannel dimensions and narrowest flow path are compatible with 20µm particles.

Agglutination Research

Large streptavidin microspheres may be evaluated in particle agglutination methods when binding of a target or bridging molecule causes measurable particle clustering.

Agglutination may be observed using:

• Microscopy

• Optical imaging

• Light-scattering methods

• Sedimentation patterns

• Automated image analysis

The relationship between aggregation and target concentration must be optimized experimentally.

Affinity Capture and Separation

The particles may be evaluated for affinity capture of biotinylated biomolecules or targets recognized by immobilized ligands.

SAPS20UM-10 is not necessarily magnetic. Particle recovery must use a method compatible with the confirmed particle material.

Compatible Biotinylated Biomolecules

Biotinylated Antibodies

Potential antibody formats include:

• Full-length IgG

• IgM

• Fab fragments

• F(ab′)₂ fragments

• Recombinant antibodies

• Single-chain variable fragments

• Single-domain antibodies

• Engineered antibody formats

Antibody activity after immobilization depends on:

• Biotinylation chemistry

• Number of biotin groups

• Location of biotin groups

• Spacer length

• Protein purity

• Antibody aggregation

• Surface loading

• Storage conditions

Biotinylated Proteins

Examples include:

• Recombinant antigens

• Enzymes

• Cytokines

• Growth factors

• Receptors

• Lectins

• Binding proteins

• Fusion proteins

• Protein standards

Biotinylated Peptides

Potential applications include:

• Epitope mapping

• Antibody screening

• Receptor-binding research

• Enzyme studies

• Protein interaction studies

• Drug-screening assays

A suitable spacer between biotin and the peptide may improve accessibility.

Biotinylated Nucleic Acids

Compatible formats may include:

• Single-stranded DNA

• Double-stranded DNA

• RNA

• Oligonucleotide probes

• PCR amplicons

• Aptamers

• Modified nucleic acid probes

• Capture sequences

Biotinylated Small Molecules

Small biotinylated compounds may be immobilized when the biotin group remains accessible.

Spacer design and molecular orientation should be considered during method development.

Recommended Biotinylated Ligand Loading Protocol

The following procedure is a general development starting point. Final conditions should be optimized for the actual biomolecule and application.

1. Resuspend SAPS20UM-10

Allow the product to reach the recommended handling temperature.

Mix by gentle inversion, rotation, or controlled vortexing until the suspension is homogeneous.

Because 20µm particles may settle quickly, mix the suspension immediately before removing each aliquot.

Continue gentle mixing during repeated sampling to reduce concentration differences between aliquots.

2. Calculate the Required Particle Amount

Determine the required amount according to:

• Number of tests

• Particles required per test

• Surface required per reaction

• Reaction volume

• Expected target concentration

• Lot-specific binding capacity

• Number of washing steps

• Expected processing loss

Do not estimate ligand-loading capacity from the solids concentration alone.

3. Transfer the Microspheres

Transfer the required amount to a clean, low-binding tube or processing vessel.

Use a pipette tip with an opening appropriate for 20µm particles.

Avoid very narrow tips that may restrict particle transfer or contribute to uneven sampling.

4. Wash the Particles

Wash the microspheres using a buffer compatible with streptavidin and the selected biotinylated ligand.

Avoid buffers containing free biotin during ligand immobilization.

Potential recovery methods include:

• Low-speed or moderate-speed centrifugation

• Membrane filtration

• Controlled sedimentation

• Other validated solid–liquid separation methods

The correct method should be determined using the actual particle material, density, buffer, volume, and recovery requirement.

5. Prepare the Biotinylated Ligand

Dilute the selected ligand in a compatible binding buffer.

Review:

• Ligand concentration

• Biotinylation level

• Molecular purity

• Aggregate level

• Free biotin content

• Free biotinylated reagent

• Buffer additives

• Protein stability

• Nucleic acid stability

6. Add the Ligand

Combine the washed particles with the biotinylated ligand.

Use gentle rotation, rocking, or controlled mixing to keep the particles suspended.

Avoid excessive vortexing, foaming, mechanical damage, and biomolecule denaturation.

7. Optimize the Incubation

Evaluate:

• Particle concentration

• Ligand concentration

• Ligand-to-particle ratio

• Incubation time

• Temperature

• Buffer pH

• Salt concentration

• Mixing speed

• Reaction volume

Continuous gentle mixing is especially important because 20µm particles may settle during incubation.

8. Remove Unbound Ligand

Separate and wash the particles to remove unbound biotinylated molecules.

Insufficient washing may increase background, while excessive washing may reduce particle recovery.

9. Block the Microsphere Surface

Incubate the ligand-loaded particles with an application-compatible blocking reagent.

Potential blockers include:

• Bovine serum albumin

• Casein

• Fish gelatin

• Non-immune immunoglobulin

• Synthetic blocking polymers

• Commercial microsphere-blocking buffers

The blocker should reduce negative-sample signal without significantly reducing target-specific binding.

10. Resuspend the Prepared Microspheres

Resuspend the coated and blocked particles in a suitable assay or storage buffer.

Evaluate:

• Particle dispersion

• Ligand retention

• Binding activity

• Non-specific binding

• Particle recovery

• Settling behavior

• Redispersion

• Short-term stability

• Long-term stability

• Microbial stability

Recommended Biological Assay Workflow

1. Prepare the Capture Microspheres

Load SAPS20UM-10 with the selected biotinylated capture molecule.

Wash and block the particles before sample testing.

2. Prepare Experimental Controls

Recommended controls may include:

• Assay-buffer blank

• Streptavidin microspheres without capture ligand

• Capture-ligand-loaded particles without target

• Negative sample

• Positive sample

• Reporter-only control

• Isotype control

• Non-relevant biotinylated ligand control

• Unlabeled target control

• Single-color controls when fluorescence is used

3. Add the Test Sample

Combine the prepared particles with the sample.

Optimize:

• Sample volume

• Sample dilution

• Particle concentration

• Particles per reaction

• Target concentration range

• Incubation time

• Incubation temperature

• Mixing method

• Sample matrix

Maintain gentle mixing throughout incubation.

4. Wash the Microspheres

Remove unbound sample components while maintaining acceptable particle recovery.

Record:

• Number of washes

• Wash-buffer composition

• Wash volume

• Separation method

• Residual supernatant volume

• Mixing procedure

5. Add the Detection Reagent

Add a fluorescent, enzymatic, colorimetric, chemiluminescent, or other compatible detection reagent.

The selected detection system must match the intended instrument and assay format.

6. Incubate and Wash

Optimize reporter concentration and incubation time.

Remove unbound detection reagent to reduce background.

7. Resuspend for Detection

Resuspend the particles in a clean detection buffer.

Mix immediately before transferring the sample to the instrument or imaging chamber.

8. Measure the Signal

Potential analytical outputs include:

• Mean or median particle fluorescence

• Percentage of positive particles

• Signal-to-background ratio

• Particle-associated enzyme activity

• Color intensity

• Agglutination level

• Particle-count changes

• Dose-response curve

• Assay precision

• Recovery

• Specificity

• Cross-reactivity

9. Analyze the Results

Establish positive and negative thresholds using appropriate controls.

Do not define a positive result using the test sample alone.

Handling, Mixing and Recovery of 20µm Microspheres

Settling

The 20µm microspheres may settle more quickly than smaller particles.

Settling can cause:

• Uneven particle concentration

• Variation between aliquots

• Inconsistent ligand loading

• Different particle counts between reactions

• Variable assay signals

• Reduced reproducibility

Mix the stock suspension immediately before every sampling step.

Maintaining a Uniform Suspension

Suitable mixing methods may include:

• Gentle inversion

• End-over-end rotation

• Slow orbital mixing

• Gentle rocking

• Controlled vortexing before use

• Intermittent pipette mixing

Avoid high-speed mixing that causes foaming or biomolecule damage.

Pipetting

Use an appropriate pipette-tip opening.

During repeated sampling:

1. Mix the stock.

2. Aspirate the required volume promptly.

3. Dispense completely.

4. Mix again before the next aliquot.

Centrifugation

The particles may be recoverable using lower centrifugal force or shorter centrifugation times than smaller microspheres, but the correct conditions depend on particle material and density.

Determine the minimum conditions that provide:

• Acceptable particle recovery

• A manageable pellet

• Easy redispersion

• Minimal aggregation

• Minimal biomolecule damage

Filtration

A membrane with an appropriate pore size may be used for recovery or washing.

Confirm:

• Particle retention

• Biomolecule compatibility

• Low non-specific adsorption

• Acceptable recovery

• Easy particle release

• Compatibility with processing volume

Controlled Sedimentation

Natural or accelerated sedimentation may be considered in some workflows.

Sedimentation-based recovery may be slower and more variable than centrifugation but can reduce mechanical stress.

Microscopy, Flow Cytometry and Microfluidic Detection

Optical Microscopy

The 20µm microspheres can generally be observed by standard optical microscopy.

Potential uses include:

• Morphology evaluation

• Aggregate inspection

• Particle counting

• Surface-binding visualization

• Cell–particle interaction imaging

• Recovery assessment

Fluorescence Microscopy

If the particle carries a fluorescent reporter, internally incorporated dye, or fluorescently labeled target, fluorescence microscopy can be used to evaluate:

• Signal localization

• Binding uniformity

• Positive and negative particles

• Cell–particle interactions

• Multiplex particle populations

Flow Cytometry

SAPS20UM-10 may be evaluated by flow cytometry when the instrument fluidics are compatible with 20µm particles.

Before use, confirm:

• Sample tubing diameter

• Flow-cell dimensions

• Nozzle or orifice size

• Sample flow rate

• Particle concentration

• Aggregate level

• Scatter detector range

The particles should remain substantially smaller than the narrowest fluidic pathway.

Imaging Flow Cytometry

The large particle size may be useful for imaging flow cytometry studies that combine particle-associated fluorescence with morphological imaging.

Microfluidics

Confirm that microchannels, constrictions, filters and valves can accommodate 20µm particles without blockage.

Blocking and Non-Specific Binding Control

Non-specific adsorption can increase background and reduce assay sensitivity.

Potential causes include:

• Inadequate blocking

• Incompatible blocking reagent

• Excess capture ligand

• Excess detection reagent

• Insufficient washing

• Aggregated antibodies

• Hydrophobic sample components

• High sample protein concentration

• Particle aggregation

• Sample-matrix interference

Screen Multiple Blocking Reagents

Compare several blocking formulations.

The preferred blocker should reduce negative-sample signal while maintaining target-specific binding.

Optimize Capture-Ligand Loading

Maximum ligand loading does not always produce maximum assay performance.

Excessive loading may:

• Cause steric crowding

• Reduce target accessibility

• Increase reagent consumption

• Increase non-specific interactions

• Increase assay variation

Titrate the Detection Reagent

Excess detection reagent can increase background.

Test several concentrations using positive and negative controls.

Optimize Washing

Evaluate:

• Number of washes

• Wash-buffer composition

• Wash volume

• Separation method

• Mixing method

• Residual supernatant

• Particle recovery

Evaluate Detergents Carefully

A small amount of compatible detergent may improve particle dispersion and reduce non-specific adsorption.

Excessive detergent may interfere with biomolecule interactions or detection reagents.

Comparison of 20µm, 10µm and 5µm Microspheres

Choose SAPS20UM-10 When:

• A large individual-particle surface is required.

• Direct microscopy is important.

• A cell-size-range particle model is preferred.

• Individual-particle analysis is required.

• Clear size-based identification is needed.

• Microfluidic manipulation is being studied.

• Large-particle agglutination research is planned.

• Strong visual confirmation of particle recovery is useful.

Choose SAPS10UM-10 When:

• A balance between large particle size and easier fluidic compatibility is desired.

• Conventional flow cytometry is a major detection method.

• Strong scatter detection is required.

• Lower settling than 20µm particles is preferred.

Choose SAPS5UM-10 When:

• A higher particle number per unit mass is needed.

• Lower settling is preferred.

• Standard bead-based flow assays are being developed.

• Smaller reaction volumes are used.

• Easier fluidic compatibility is important.

Final selection should be based on the intended biological application, instrument capability, required particle number, ligand loading, settling behavior, recovery method and detection platform.

Quality Control and Batch Consistency

Potential quality-control parameters include:

• Mean particle diameter

• Particle-size range

• Particle-size distribution

• Particle-size coefficient of variation

• Particle morphology

• Suspension appearance

• Solids content

• Streptavidin coating consistency

• Biotin-binding capacity

• Particle dispersion

• Aggregate level

• Settling rate

• Redispersion performance

• Particle recovery

• Background signal

• Non-specific binding

• Microbial control

• Packaging integrity

• Storage stability

• Lot-to-lot consistency

Particle-Size Testing

Particle-size characterization may report:

• Mean diameter

• Median diameter

• Size range

• Size distribution

• Coefficient of variation

• Microscopy results

• Instrumental particle-size data

The measurement method should be stated when reporting particle-size results.

Biotin-Binding Capacity

Binding capacity should be measured with a defined biotinylated probe.

The measured result can be influenced by:

• Probe type

• Molecular size

• Biotinylation level

• Probe purity

• Incubation conditions

• Buffer composition

• Detection method

• Calculation basis

Values obtained using different probes or methods may not be directly comparable.

Functional Quality Control

A functional QC assay may evaluate:

• Binding of a standardized biotinylated probe

• Percentage of positive particles

• Signal distribution

• Background separation

• Particle recovery

• Aggregate population

• Repeatability

• Redispersion after storage

Lot-Specific Documentation

Available documentation may include:

• Certificate of Analysis

• Product specification

• Particle-size results

• Solids-content results

• Binding-capacity results

• Safety Data Sheet

• Handling instructions

• Storage recommendations

• Lot number

• Production date

Required release tests and acceptance criteria should be agreed upon before bulk manufacturing.

Bulk Manufacturing and Customization

Shanghai SanYu Biotechnology Co., Ltd. supplies SHBC streptavidin microspheres for laboratory research, pilot development, repeated production and enterprise bulk purchasing.

Research Sample Evaluation

Samples may be evaluated for:

• Particle morphology

• Particle dispersion

• Streptavidin activity

• Biotinylated ligand loading

• Non-specific binding

• Particle recovery

• Assay feasibility

• Microscopy compatibility

• Flow-system compatibility

• Settling and redispersion

Pilot-Scale Development

Pilot batches may support:

• Assay optimization

• Binding-capacity verification

• Stability studies

• Buffer selection

• Preservative evaluation

• Packaging evaluation

• Quality-control development

• Customer verification

• Process transfer

Bulk Production

Bulk manufacturing can be arranged after technical requirements and release specifications have been confirmed.

Please provide:

• Required quantity

• Expected annual demand

• Preferred package size

• Intended biological application

• Required particle diameter

• Required solids content

• Required binding capacity

• Biotinylated ligand type

• Buffer requirements

• Preservative restrictions

• Quality-control requirements

• Documentation requirements

• Delivery schedule

• Delivery destination

Custom Particle Diameter

Alternative particle sizes may be discussed according to application and manufacturing feasibility.

Custom Streptavidin Loading

Project-specific streptavidin coating levels or binding-capacity targets may be evaluated.

Custom Fluorescence or Color Coding

For imaging and multiplex projects, fluorescently encoded or visibly colored streptavidin microspheres may be discussed.

Potential options may include:

• Different excitation wavelengths

• Different emission wavelengths

• Multiple fluorescence colors

• Multiple fluorescence intensities

• Visible particle colors

• Customer-specific coding systems

Custom Buffer and Concentration

Alternative solids concentrations, buffer formulations, surfactants, preservative systems and packaging formats may be evaluated.

OEM and Private-Label Supply

Available cooperation formats may include:

• OEM packaging

• Customer-specific labels

• Private-label supply

• Customer-specific catalog numbers

• Bulk raw material supply

• Customized technical documents

• Customer-specific release specifications

Storage and Stability Recommendations

Follow the final product label, technical data sheet and lot-specific Certificate of Analysis.

General recommendations include:

• Store under the specified refrigerated conditions.

• Do not freeze unless freeze–thaw stability has been validated.

• Keep the container tightly closed.

• Store the vial upright.

• Mix thoroughly before sampling.

• Maintain particles in suspension during processing.

• Use clean pipette tips and low-binding tubes.

• Avoid contamination of the original suspension.

• Do not allow the particles to dry.

• Avoid repeated unnecessary temperature changes.

• Do not return diluted material to the original container.

• Record the product lot number and opening date.

Streptavidin-coated particles should generally remain in liquid during storage and handling. Drying or freezing can reduce performance. an reduce performance. citeturn146812search1turn146812search5

Settling and Resuspension

Because SAPS20UM-10 contains large particles, settling may occur quickly.

Before use:

1. Allow the vial to reach the recommended handling temperature.

2. Gently invert or rotate the vial.

3. Apply controlled vortexing when necessary.

4. Confirm that the suspension is homogeneous.

5. Mix immediately before sampling.

6. Inspect for irreversible aggregates.

Reversible settling does not necessarily indicate product failure.

Avoid Drying

Do not allow the particle pellet to dry during washing.

Drying may cause:

• Irreversible aggregation

• Reduced streptavidin activity

• Difficult redispersion

• Increased assay background

• Reduced particle recovery

Avoid Freezing

Freezing may cause:

• Particle aggregation

• Changes in suspension stability

• Reduced protein activity

• Reduced particle recovery

• Increased assay variability

Evaluate Prepared Reagent Stability

Ligand-loaded and blocked microspheres may have different stability from the original SAPS20UM-10 suspension.

Evaluate the final prepared reagent under the intended storage, transport and operating conditions.

Troubleshooting Guide

Weak Biotinylated Ligand Binding

Possible causes:

• Free biotin in the buffer

• Unremoved biotinylated reagent

• Low ligand biotinylation

• Inaccessible biotin groups

• Insufficient ligand concentration

• Inadequate incubation time

• Inactive streptavidin

• Incompatible buffer

• Particle settling during incubation

Recommended actions:

• Remove free biotin.

• Purify the biotinylated ligand.

• Verify biotinylation.

• Evaluate a suitable spacer.

• Maintain gentle mixing.

• Increase ligand concentration gradually.

• Test a positive-control biotinylated ligand.

High Background Signal

Possible causes:

• Insufficient blocking

• Excess detection reagent

• Inadequate washing

• Non-specific reagent adsorption

• Sample-matrix interference

• Aggregated antibodies

• Excess capture-ligand loading

Recommended actions:

• Compare different blockers.

• Titrate the detection reagent.

• Optimize washing.

• Remove protein aggregates when appropriate.

• Dilute the sample.

• Reduce capture-ligand loading.

Unequal Results Between Aliquots

Possible causes:

• Rapid particle settling

• Inadequate stock mixing

• Delay between mixing and sampling

• Narrow pipette-tip opening

• Inconsistent transfer technique

Recommended actions:

• Mix immediately before every aliquot.

• Use an appropriate pipette tip.

• Maintain slow continuous mixing during repeated dispensing.

• Standardize the sampling interval.

Particle Aggregation

Possible causes:

• Incompatible buffer

• Extreme pH

• High ionic strength

• Freezing

• Drying

• Excessive ligand loading

• Insufficient stabilizer

• Microbial contamination

Recommended actions:

• Evaluate buffer compatibility.

• Avoid freezing and drying.

• Optimize ligand loading.

• Use controlled gentle mixing.

• Review stabilizer and preservative requirements.

Low Particle Recovery

Possible causes:

• Loss during supernatant removal

• Adhesion to tubes

• Incorrect filter pore size

• Incomplete sedimentation

• Incomplete transfer

• Excessive washing

• Particle settling inside pipette tips

Recommended actions:

• Use low-binding tubes.

• Optimize separation conditions.

• Validate the filter membrane.

• Mix before every transfer.

• Reduce unnecessary wash steps.

• Leave a controlled residual volume above the pellet.

Frequently Asked Questions

What is SAPS20UM-10?

SAPS20UM-10 is a 20µm streptavidin-coated microsphere suspension supplied at 1% solids for capturing biotinylated biomolecules in biological research and bead-based assays.

What is the SHBC brand?

SHBC is the microsphere and biotechnology material brand of Shanghai SanYu Biotechnology Co., Ltd.

What is the nominal particle diameter?

The nominal particle diameter is 20µm.

The measured diameter, size range and particle-size distribution should be confirmed using lot-specific documentation.

What is the solids content?

SAPS20UM-10 is supplied at 1% solids.

Are SAPS20UM-10 microspheres magnetic?

The product should not be assumed to be magnetic unless magnetic properties are specifically stated in the product specification.

For magnetic separation, select a product specifically described as streptavidin magnetic beads.

Are the microspheres fluorescent?

The standard product should not be assumed to contain an internal fluorescent dye unless fluorescence is specifically stated.

A fluorescently encoded version may be discussed as a custom product.

Which molecules can bind to SAPS20UM-10?

The streptavidin surface can capture biotinylated antibodies, antigens, proteins, peptides, enzymes, receptors, oligonucleotides, DNA, RNA, aptamers and other biotin-containing molecules.

Can an unmodified antibody bind directly?

An unmodified antibody will not specifically attach through the streptavidin–biotin interaction unless it is first biotinylated or connected through another compatible reagent.

Is EDC/NHS activation required?

EDC/NHS activation is normally not required when loading a biotinylated molecule onto streptavidin-coated microspheres.

What is the biotin-binding capacity?

Binding capacity should be confirmed using the product specification or lot-specific Certificate of Analysis.

It should not be estimated from solids content alone.

Why choose 20µm microspheres?

The 20µm particles provide a large surface per individual particle, clear microscopy visibility, cell-size-range dimensions and convenient particle identification.

Do 20µm microspheres have more surface area than smaller particles?

Each 20µm particle has more surface area than each smaller particle.

However, smaller particles generally provide more particles and greater total surface area per unit mass.

Why do the particles settle quickly?

Large particles typically settle faster than smaller microspheres.

Mix the stock immediately before sampling and maintain gentle mixing during incubation.

Can SAPS20UM-10 be used in flow cytometry?

It may be evaluated in flow cytometry when the instrument fluidics, flow cell and sample pathway are compatible with 20µm particles.

Can it be used for microscopy?

Yes. The large particle size is suitable for evaluation by optical, fluorescence or confocal microscopy.

Can SAPS20UM-10 be used as a cell model?

The 20µm size may be useful in cell-size-range particle research.

However, synthetic microspheres do not reproduce all optical, mechanical, chemical or biological properties of living cells.

Can the microspheres be used for immunoassays?

Yes. A biotinylated capture antibody may be immobilized on the particle, followed by target capture and detection with an appropriate reporter.

Can the particles be used for nucleic acid capture?

Yes. Biotinylated oligonucleotides, DNA, RNA, PCR products and aptamers may be evaluated for immobilization and target capture.

Can SAPS20UM-10 be used in multiplex assays?

Yes, provided that the 20µm population can be distinguished from other particle populations.

Size coding, fluorescence coding or color coding may be considered.

How should the particles be washed?

The washing method depends on particle material, density, buffer, volume and required recovery.

Centrifugation, filtration or controlled sedimentation may be evaluated.

How can non-specific binding be reduced?

Optimize the blocking reagent, capture-ligand concentration, detection-reagent concentration, washing conditions, detergent level, sample dilution and incubation time.

Can buffers containing free biotin be used?

Free biotin may occupy streptavidin-binding sites and should generally be avoided during capture-ligand loading.

Should the product be diluted before use?

Yes. Prepare a working concentration according to the required particle number, assay volume and detection method.

Can SAPS20UM-10 be frozen?

Freezing is generally not recommended unless freeze–thaw stability has been specifically validated.

Can the concentration be customized?

Alternative solids concentrations may be discussed according to project requirements and manufacturing feasibility.

Can the binding capacity be customized?

Project-specific streptavidin coating levels or binding-capacity targets may be evaluated.

Can fluorescent 20µm streptavidin microspheres be produced?

Fluorescently encoded or visibly colored 20µm streptavidin microspheres may be discussed for qualified imaging, microfluidic and multiplex projects.

Is bulk production available?

Yes. Shanghai SanYu Biotechnology Co., Ltd. supports samples, pilot batches, repeated orders, OEM projects and bulk production.

What information is required for a quotation?

Please provide:

• Catalog number SAPS20UM-10

• Required quantity

• Expected annual purchasing volume

• Preferred package size

• Intended biological application

• Type of biotinylated ligand

• Required binding capacity

• Required number of particles per test

• Detection method

• Buffer restrictions

• Preservative restrictions

• Quality-control requirements

• Documentation requirements

• Delivery destination

Request a Sample or Bulk Quotation

SHBC SAPS20UM-10 20µm Streptavidin Microspheres provide a large, clearly identifiable particle platform for immobilizing biotinylated antibodies, proteins, peptides, enzymes, receptors, oligonucleotides, DNA, RNA, aptamers and other biotin-labeled molecules.

The product is suitable for:

• Biological assay development

• Bead-based immunoassays

• Antibody immobilization

• Protein interaction research

• Nucleic acid capture

• Hybridization assays

• Cell–particle interaction studies

• Microscopy and imaging

• Microfluidic research

• Agglutination research

• Size-coded multiplex systems

• Research reagent manufacturing

SAPS20UM-10 provides:

• 20µm nominal particle diameter

• Streptavidin-functional surface

• 1% solids suspension

• Large surface per individual particle

• Clear microscopic visibility

• Compatibility with biotinylated biomolecules

• Sample and pilot-batch supply

• Bulk manufacturing capability

• OEM and custom-development support

For sample evaluation or bulk purchasing, provide the intended application, required quantity, biotinylated ligand, desired binding capacity, detection platform, packaging requirements and quality-control specifications.

Product Name: 20µm Streptavidin Microspheres
Catalog Number: SAPS20UM-10
Brand: SHBC
Manufacturer: Shanghai SanYu Biotechnology Co., Ltd.
Nominal Particle Diameter: 20µm
Surface Modification: Streptavidin
Solids Content: 1%
Primary Application: Biological Research and Bead-Based Assays
Supply Capability: Samples, Pilot Batches and Bulk Production
Intended Use: Research Use Only. Not for diagnostic or therapeutic use.