CY5.5-PEG5000-Mal

Cat. No.: C1452373

Storage

Store at -20°C

Shipped In

Ice chest + Ice pads

Visão geral

CY5.5-PEG5000-Mal is used for preparing fluorescently labeled molecules. It is formed by condensing maleimide groups (Mal), PEG5000, and fluorescent dye CY5.5.

Specifications

Condições de armazenamento de armazenamento

Store at -20°C

Enviado em

Ice chest + Ice pads

Este produto requer transporte de cadeia fria. Serviços terrestres e outros serviços econômicos não estão disponíveis.

Application Protocols

Tested applications, recommended dilutions, and positive control data are not specified for this item; refer to CoA/Spec Sheet. As this is a general labeling reagent rather than an assay‑ready kit, users should develop and validate protocols appropriate to their substrates and instrumentation. See Reaction Conditions and Buffer Applications tabs for general planning considerations.

Biological Roles

This product is a synthetic labeling reagent; it does not possess intrinsic biological roles. The following points describe how its components interact with biological systems in research contexts (general, literature):

• PEG (polyethylene glycol):
  • Biologically inert, hydrophilic polymer that reduces nonspecific interactions and aggregation; used widely to improve colloidal stability of bioconjugates and surfaces.
• Maleimide–thiol chemistry:
  • Exploits the nucleophilicity of cysteine thiols at near‑neutral pH to achieve site‑selective modification of biomolecules, forming nonreducible thioether bonds that are stable under most physiological conditions.
• Cy5.5 fluorophore:
  • A near‑infrared cyanine dye with absorption/emission in the 675/694–705 nm range (literature), minimizing autofluorescence from biological matrices and enabling deep‑red/NIR detection in imaging and assay readouts.
• Spacing effects:
  • The ~5 kDa PEG spacer increases hydrodynamic radius and distances the dye from the biomolecule surface, which often improves fluorescence quantum yield and reduces quenching by proximal aromatic residues or metals.
• Surface and nanoparticle labeling:
  • PEGylated NIR labels are commonly employed to passivate and functionalize nanoparticles, biosensors, and microarrays to achieve high signal‑to‑background in complex media.

All uses are for laboratory research only. No medical, diagnostic, or therapeutic claims are made or implied for this material.

Buffer Applications

This product is not a buffering agent. However, buffer choice is critical for successful maleimide–thiol conjugation (general, literature guidance):

• Recommended conjugation buffers:
  • Phosphate or HEPES, pH 6.5–7.2; include 0.5–5 mM EDTA to suppress metal‑catalyzed thiol oxidation.
  • Ionic strength 50–150 mM NaCl helps maintain protein stability and reduces nonspecific interactions.
• Avoid during conjugation:
  • Tris, glycine, or other primary amine buffers; they can react or accelerate maleimide hydrolysis.
  • pH >7.5, which increases hydrolysis of maleimide to maleamic acid (loss of reactivity).
• Reducing agents:
  • Use TCEP at ≤1–5 mM during disulfide reduction at pH ≤7.0, then remove prior to labeling. Avoid DTT/β‑mercaptoethanol in the labeling step due to competitive thiols.
• Quenching and storage buffers:
  • After labeling, unreacted maleimide can be quenched with cysteine (1–5 mM). Store labeled biomolecules in PBS/HEPES at pH 7.2–7.5, optionally with glycerol or sugars for stability (application‑dependent).

For electrophoresis or cell‑based assays, validate that residual DMSO (if used) is ≤0.1–0.5% to avoid perturbing biological systems.

Green Alternatives

Sustainability considerations for dye–PEG–maleimide labeling focus on solvent selection, atom economy of coupling, and waste minimization.

Greener choices (general, literature):

• Favor aqueous conjugation:
  • Prepare concentrated anhydrous DMSO stocks, then dilute immediately into amine‑free aqueous buffers (pH 6.5–7.0). This minimizes aprotic polar solvent volumes and reduces VOC waste.
• Buffer and reagent choices:
  • Use HEPES or phosphate buffers instead of organic amine buffers (e.g., Tris) during conjugation; they are benign and do not compete with maleimide.
  • Prefer TCEP (odorless, non‑volatile) over β‑mercaptoethanol for disulfide reduction; remove excess reducer prior to labeling to avoid quenching.
• Waste reduction:
  • Scale reactions to actual need using DOL calculators; quench unreacted maleimide with a benign thiol (e.g., cysteine) to ease downstream disposal.

Comparison (literature; tradeoffs):

• DMSO vs water-only labeling:
  • Water-only labeling is greener but may suffer from limited solubility or aggregation; small percentages of DMSO (≤5–10%) often strike a balance.
• Alternative fluorophores:
  • More photostable dyes (e.g., sulfonated cyanines or certain carbopyronines) can reduce required dye loadings, thereby lowering waste. However, cross‑study comparability may favor Cy5.5 due to established instrumentation filters.

Note: Wherever possible, recover and re‑use desalting columns and use microspin formats to minimize buffer consumption.

Pharmaceutical Uses

No pharmacopeial status or clinical/formulation use is claimed or provided for this item. This material is supplied strictly for laboratory research use only.

General context (literature, for background only):

• PEG spacers are widely used in pharmaceutical development to modulate solubility and reduce nonspecific interactions; however, this product is not qualified for GMP manufacturing or clinical applications.
• NIR dyes like Cy5.5 are commonly used in preclinical assay development, analytical method development, and imaging tool creation. Translation to clinical use requires extensive additional qualification (purity, residuals, stability, biocompatibility), which is beyond the scope of this research‑grade product.
• Excipients/impurities: Not specified for this item; refer to CoA/Spec Sheet if you require limits for process development feasibility studies.

If your work requires regulated‑grade materials (e.g., GMP linkers or dyes), contact technical support to discuss custom sourcing and documentation.

Physical Properties

Item-specific numerical specifications are not provided in the Product Data.

• Appearance: Not specified for this item; refer to CoA/Spec Sheet.
• Molecular weight (exact): Not specified for this item; refer to CoA/Spec Sheet. (General: PEG5000 contributes ~5 kDa; total MW depends on the Cy5.5 variant and linkages.)
• Solubility (general, literature):
  • Highly soluble in polar organic solvents (DMSO, DMF). Often soluble/dispersible in aqueous buffers due to PEGylation; final solubility depends on counterions and dye substitution pattern.
  • Avoid alcohols or high‑pH buffers for stock solutions before conjugation because maleimide can hydrolyze.
• Photophysical properties (Cy5.5 dye, literature values; formulation-dependent):
  • Absorption (λmax) ~675 nm in aqueous media; secondary shoulder near 600–620 nm typical for cyanines.
  • Emission (λem) ~694–705 nm; quantum yield and extinction coefficient depend on microenvironment and substitution.
• LogP/pKa/refractive index: Not specified for this item; refer to CoA/Spec Sheet. (Cyanine dyes are cationic/zwitterionic; PEG is neutral; maleimide is neutral but electrophilic.)
• Stability (general): Maleimide undergoes ring hydrolysis at basic pH (>7.5–8.0), reducing thiol reactivity; cyanine dyes are light‑sensitive and may photobleach; PEG backbone is chemically robust.

Always consult the CoA/SDS for any batch‑specific constants and rely on small‑scale test dissolutions to confirm working solubility in your chosen medium.

Quality and Grades

• Grade/purity: Not specified for this item; refer to CoA/Spec Sheet.

Interpretation and implications (general guidance for this product class):

• Dye–PEG conjugates are typically supplied as research-grade materials with QA release based on identity (e.g., UV‑Vis profile for Cy5.5), functionality (maleimide reactivity), and average molecular weight distribution (GPC for PEG). If applicable, residual solvents, water content, and endotoxin/bioburden may be reported—defer to the specific CoA.
• Absorbance ratio checks (literature): The Amax at ~675 nm relative to a pegylated background baseline helps confirm dye loading and absence of aggregates; however, numeric thresholds are batch‑specific.
• Functional group integrity: Maleimide content can be assessed by thiol titration (e.g., Ellman’s reagent post‑conjugation control) or NMR signals characteristic of maleimide olefin protons; again, refer to CoA for acceptance criteria.
• Stabilizers: Not specified for this item; refer to CoA/Spec Sheet. Many suppliers avoid stabilizers for bioconjugation‑ready reagents; handle under inert, anhydrous, light‑protected conditions to preserve functionality.
• What to verify upon receipt:
  • UV‑Vis spectrum in a suitable solvent (DMSO or PBS) to confirm expected λmax near 675 nm (literature).
  • Quick small‑scale thiol conjugation test (e.g., with a cysteine‑containing peptide) to confirm reactivity before committing valuable biomolecules.

Contact technical support with your application details if you require specific grade definitions (e.g., low endotoxin, anhydrous, or chromatography-grade documentation).

Reaction and Applications

CY5.5-PEG5000-Mal enables site‑selective thiol bioconjugation and materials labeling with NIR fluorescence readouts.

Key application families (general, literature):

• Protein/peptide labeling:
  • Cysteine‑selective modification via Michael addition to the maleimide, yielding stable thioether linkages. PEG5000 spacing can reduce steric hindrance near active sites and minimize dye–protein interactions, improving photophysics and solubility.
• Antibody and nanobody labeling:
  • Controlled partial reduction of interchain disulfides (e.g., with TCEP at pH ≤7.0) followed by labeling affords NIR‑fluorescent conjugates for research imaging and assay development.
• Nucleic acid and nanoparticle surfaces:
  • Labeling of thiolated oligos or thiol‑functionalized surfaces (Au–S assemblies, thiolated silica) to build NIR‑readout probes and surfaces. PEG reduces nonspecific adsorption and improves colloidal stability.
• Assay and biosensor development:
  • FRET pairs using Cy5.5 as acceptor/donor (depending on partner), fluorescence anisotropy assays, and in‑gel or in‑solution detection.

Practical tips (literature/practice):

• Maintain pH 6.5–7.2 during coupling to balance thiol nucleophilicity and maleimide stability. Avoid pH >7.5.
• Degas buffers and include EDTA to prevent thiol oxidation. Prefer TCEP over DTT during the coupling step (DTT competes as a thiol); if DTT is used to reduce, remove it thoroughly before labeling.
• Control degree of labeling (DOL) by stoichiometry (typically 1–3 equivalents of dye per accessible thiol), time (0.5–2 h at room temperature), and temperature (4–25°C). Protect from light throughout.

Reaction Conditions

Typical conditions for maleimide–thiol conjugation with CY5.5-PEG5000-Mal (general, literature guidance; optimize per system):

• Substrates: Proteins/peptides with free cysteines, thiolated oligonucleotides, or thiol‑functionalized surfaces/particles.
• Buffer: Phosphate or HEPES, pH 6.5–7.2; 50–150 mM NaCl; 0.5–5 mM EDTA. Degas to limit O2.
• Solvent: Add dye from anhydrous DMSO/DMF stock to give ≤5–10% organic cosolvent after dilution.
• Stoichiometry: 1–3 equivalents of dye per accessible thiol for proteins; higher excess (5–10 eq) for surfaces or dilute systems.
• Temperature/time: 20–25°C for 30–120 min; for sensitive proteins, 4–8°C with extended time (2–16 h). Protect from light.
• Reducing conditions: If disulfide reduction is needed, use TCEP at pH ≤7.0, then remove prior to adding dye (spin columns, desalting) to avoid competition.
• Quenching: After desired DOL is reached, quench unreacted maleimide with cysteine or 2‑mercaptoethanesulfonate.
• Workup: Desalt or dialyze to remove excess dye and small molecules; monitor by UV‑Vis (A675) and protein assays to calculate DOL.

Expected outcomes (literature):

• High conversions are typical under these conditions; succinimidyl thioether linkages are stable near neutral pH. Avoid prolonged exposure to pH >8 to minimize retro‑Michael or hydrolytic side reactions.

Always perform small‑scale pilots to fine‑tune equivalents and time for your specific substrate.

Safety and Handling

Hazard classifications are not provided in the Product Data.

• GHS classification, signal word, pictograms, H‑statements: Not specified for this item; refer to SDS for authoritative safety information.

General laboratory safety guidance for cyanine dye–PEG–maleimide reagents (literature/practice):

• Likely hazards: May cause skin/eye/respiratory irritation. Maleimide groups are electrophilic Michael acceptors and can alkylate thiols; avoid contact with skin and eyes. DMSO stocks can enhance dermal absorption of solutes—prevent skin contact.
• PPE: Lab coat, nitrile gloves, safety glasses; handle powders/lyophilizates in a fume hood or ventilated enclosure to avoid dust/aerosol inhalation.
• Handling precautions:
  • Protect from light to minimize photobleaching and photo‑degradation.
  • Work under dry conditions; maleimide slowly hydrolyzes in aqueous/basic environments.
  • Avoid amine‑containing buffers (e.g., Tris) during conjugation; they can compete or promote hydrolysis.
• Incompatibilities: Strong bases, nucleophiles (primary amines), reducing agents that generate free thiols unintentionally, and oxidants that consume thiols.
• First aid (overview; consult SDS):
  • Skin/eye contact: Rinse with water for at least 15 minutes; remove contaminated clothing; seek medical advice.
  • Inhalation: Move to fresh air; obtain medical attention if symptoms persist.
  • Ingestion: Rinse mouth; do not induce vomiting; seek medical attention.
• Spills/waste: Absorb with inert material, avoid light, collect in appropriate container for disposal according to local regulations.

For research use only. Not for human or veterinary use.

Solvent Selection

CY5.5-PEG5000-Mal is a polar, amphiphilic reagent. Solvent choice should preserve maleimide reactivity, maintain dye integrity, and match the target substrate’s solubility.

• Preferred stock solvent (practice):
  • Anhydrous DMSO or DMF for concentrated stocks (e.g., 5–20 mM), protected from light. These maintain maleimide integrity and dissolve PEGylated dyes efficiently.
• Aqueous media:
  • For immediate conjugation, dilute stock into oxygen‑poor, amine‑free buffers (e.g., PBS, HEPES) at pH 6.5–7.2. Include 0.5–5 mM EDTA to chelate metals that catalyze thiol oxidation.
• Avoid before conjugation:
  • Primary amines (Tris, glycine), high pH (>7.5–8.0), and prolonged aqueous storage—each promotes maleimide hydrolysis to maleamic acid (loss of reactivity).
• Miscibility profile (general):
  • DMSO/DMF: Miscible with water—facilitates rapid dilution into buffer.
  • Alcohols: Less ideal; can affect dye spectra and may accelerate hydrolysis at basic pH.
• When to choose alternatives:
  • If fully aqueous labeling is needed, use sulfonated Cy5.5 derivatives or add minimal DMSO (≤10% v/v) to maintain solubility without perturbing biomolecules.

Quick comparison (literature, general):

• DMSO: Best solvency, good stability; manage potential protein denaturation above ~10% v/v.
• DMF: Similar to DMSO; typically used for synthetic coupling steps.
• Aqueous buffer (pH 6.5–7.0): Optimal for reaction phase after immediate dilution from an anhydrous stock.

Storage and Reconstitution

• Storage conditions (item-specific from Product Data): Store at −20°C. Shipped in an ice chest with ice pads. For research use only.

General best practices for this class of reagents (literature/practice):

• Light/moisture protection: Store in amber, airtight containers with desiccant. Minimize freeze–thaw cycles; if supplied lyophilized, keep vial tightly capped under dry atmosphere.
• Stock solution preparation:
  • Reconstitute in anhydrous DMSO or DMF to prepare a concentrated stock (e.g., 5–20 mM). Filter (0.2 μm PTFE) if particulates are observed. Aliquot into light‑protected microtubes and refreeze at −20°C to avoid repeated thawing.
  • For immediate use, dilute the organic stock into amine‑free buffer (pH 6.5–7.2) to the working concentration while gently mixing and protecting from light.
• Stability considerations:
  • Maleimide undergoes hydrolysis at elevated pH and on prolonged exposure to water; prepare only the volume needed for a given session.
  • Cyanine dyes are photolabile; avoid strong light during handling and storage.
• Thawing/handling: Warm to room temperature before opening to prevent condensation ingress. Work quickly in low‑humidity conditions.

Any batch‑specific reconstitution notes (e.g., exact solvent recommendations, concentration limits) are Not specified for this item; refer to CoA/Spec Sheet.

Structure and Identity

CY5.5-PEG5000-Mal is a thiol-reactive, near‑infrared (NIR) fluorescent labeling reagent comprising a Cy5.5-class cyanine fluorophore tethered through a poly(ethylene glycol) spacer of nominal average molecular weight ~5 kDa (PEG5000) bearing a terminal maleimide group for cysteine-selective conjugation.

• SKU: C1452373
• Product name: CY5.5-PEG5000-Mal
• CAS: Not specified for this item; refer to CoA/Spec Sheet.
• Molecular formula: Not specified for this item; refer to CoA/Spec Sheet.
• Molecular weight: Not specified for this item; refer to CoA/Spec Sheet.
• SMILES / InChI / InChIKey: Not specified for this item; refer to CoA/Spec Sheet.

Structural features (general, literature):

• Fluorophore: Cy5.5-type heptamethine cyanine with two indolenine rings linked by a polymethine chain; typically carries sulfonate or other polar substituents to enhance aqueous compatibility (formulation-dependent across suppliers).
• Linker: Linear PEG chain (~110–115 ethylene oxide units on average for PEG5000), conferring hydrophilicity, extended reach, and reduced nonspecific interactions.
• Reactive handle: Maleimide (cis-di‑substituted cyclohex-2-ene-1,4-dione imide) as a soft Michael acceptor that couples selectively to thiols to form stable thioether bonds.
• 2D description in words: Aromatic indolenine–polymethine–indolenine core (dye) connected via an amide/urethane-type junction to a flexible repeating –CH2–CH2–O– chain (PEG), terminating in a five‑membered maleimide ring activated toward conjugate addition by thiolates.

Notes:

• Exact microheterogeneity is inherent to PEG5000 (Poisson distribution of chain lengths). Any batch-specific identifiers (exact average Mn, dye-to-PEG stoichiometry) should be confirmed on the CoA.

Synthetic Utility

From a synthetic perspective, CY5.5-PEG5000-Mal is a modular, bifunctional handle combining photophysical reporting (Cy5.5), solubility/spacing (PEG5000), and chemoselective reactivity (maleimide). This makes it valuable for late‑stage functionalization of complex substrates.

Key functional elements and transformations (general, literature):

• Maleimide electrophile:
  • Undergoes Michael addition with thiolates to form robust thioether linkages; exhibits soft electrophile selectivity (S >> N,O) at pH ~6.5–7.2.
  • Can be converted to succinimide thioethers that are largely stable; at higher pH over time, succinimide ring opening may occur—consider post‑conjugation stabilization strategies if needed.
• PEG spacer:
  • Enhances solubility in polar media, reduces aggregation, and increases effective reach to buried cysteines or surface thiols on materials.
• Cyanine dye:
  • Enables optical tracking, quantification, and FRET‑type measurements. Dye presence can be used as an analytical handle by UV‑Vis or fluorescence.

Retrosynthetic value:

• Allows installation of a reporting group without perturbing core scaffold synthesis; thiol installation (cysteine residues, thiolated ligands, or surface thiols) can be planned upstream, leaving dye attachment to the final step under mild conditions.

Complementary chemistries:

• Orthogonal handles such as azide/alkyne (click) or NHS esters may be used in parallel on other sites; maleimide selectivity helps maintain orthogonality in multi‑step labeling workflows.

Target Specificity

No target specificity data (e.g., antigen, epitope, species reactivity, clone, isotype) are provided for this product. This is a general thiol‑reactive fluorescent labeling reagent and is not an antibody or affinity reagent. Refer to Reaction & Applications and Synthetic Utility for applicable use cases.