OPSS-PEG-OPSS - MW 2000 Da

Cat. No.: O164120

GRADE & PURITY MW 2000 Da

Storage

Room temperature

Shipped In

Normal

Vue d’ensemble

Ortho-pyridyl disulfide (OPSS) functionalized polyethylene glycol (OPSS PEG) is a thiol (-SH) group reactive PEG derivative that can be used to modify biomolecules or other materials via their available thiol groups. Ortho-pyridyl disulfide reacts with thiol group to form a stable disulfide bond while a thiol pyridyl group is released.

Specifications

Spécifications et pureté

MW 2000 Da

Conditions de stockage de stockage

Room temperature

Expédié en

Normal

Propriétés chimiques et physiques

• Solubilité: Off-white/white solid or viscous liquid depends on molecule weight;Soluble in regular aqeous solution as well as most organic solvents

Application Protocols

Tested/validated applications and recommended conditions: Not specified for this item; refer to CoA/Spec Sheet and SDS.

Note: As a general resource, consult peer‑reviewed literature for OPSS‑thiol conjugation workflows appropriate to your substrate (protein, peptide, nanoparticle, surface). Avoid thiol‑containing reductants during coupling and verify completion by UV–vis at ~343 nm.

Biological Roles

Item-specific biological data: Not specified for this item.

General context in biochemical research (literature/general):

• OPSS‑PEG‑OPSS is a synthetic linker, not a natural metabolite. It serves as a hydrophilic, flexible spacer to modulate biomolecular interactions in vitro.
• Roles in research workflows:
  • Site‑directed conjugation to cysteine residues creates defined disulfide bridges, enabling reversible immobilization or labeling strategies.
  • PEGylation reduces nonspecific adsorption and aggregation in assays, improving signal‑to‑noise in proteomics, biosensing, and nanomaterials handling.
  • Bifunctional OPSS ends enable crosslinking of thiol‑bearing macromolecules to form redox‑responsive hydrogels for biomaterials research.
• Biophysical effects (literature):
  • PEG increases hydrodynamic radius and water structuring around conjugates; the disulfide linkage permits reductive cleavage to recover native functionality when needed.

Note: All uses are for laboratory research only; no clinical or in vivo claims are made for this product.

Buffer Applications

This product is not a buffer reagent per se. However, buffer choice critically affects OPSS‑thiol conjugation chemistry (literature/general):

• Recommended buffers: Phosphate or HEPES, pH 7.0–8.0, with 0.5–5 mM EDTA to chelate metals and minimize thiol oxidation.
• Avoid: Thiol‑containing agents (DTT, β‑mercaptoethanol, TCEP) during coupling—they reduce/consume OPSS end groups. Also avoid high concentrations of primary thiol‑bearing additives (e.g., cysteine) unless stoichiometrically intended.
• Ionic strength: 50–200 mM salt can improve solubility and reduce nonspecific interactions for protein work (literature).
• Degassing: Argon or nitrogen sparging limits oxygen‑driven thiol oxidation.
• Practical recipe (illustrative; literature): 50 mM phosphate, 150 mM NaCl, 1–2 mM EDTA, pH 7.2–7.4. Filter (0.22 μm) prior to use.

Item-specific buffer instructions: Not specified for this item; refer to CoA/Spec Sheet if provided.

Green Alternatives

Green chemistry context (literature/general):

• The OPSS handle enables aqueous‑phase conjugation at ambient temperature, minimizing organic solvent use and energy input compared to some alternative chemistries.

Comparison of thiol‑reactive PEG end groups (trade‑offs; literature):

• OPSS (2‑pyridyl disulfide):
  • Pros: Aqueous compatibility; traceless release of chromophoric pyridine‑2‑thione for reaction monitoring; forms reducible disulfide link.
  • Cons: Sensitive to reductants; can be slowly consumed by adventitious thiols.
• Maleimide:
  • Pros: Very fast, selective Michael addition to thiols near neutral pH; forms stable thioether (nonreducible).
  • Cons: Hydrolysis of maleimide at higher pH; potential ring‑opened side products; may require organic cosolvent.
• Vinyl sulfone:
  • Pros: Stable handles; robust thioether formation over pH 7–8.5.
  • Cons: Slower kinetics than maleimide; may need higher pH.

Greener practice suggestions:

• Prefer water or water‑miscible media (DMSO/DMF minimal percentage) and ambient temperatures.
• Use catalytic oxygen removal (argon sparge) instead of excess chemical reductants.
• Apply stoichiometric control to limit thiol excess and minimize quenching waste.
• Employ aqueous SEC or dialysis for purification, reducing halogenated solvent usage.

Pharmaceutical Uses

Item-specific pharmacopeial status/excipient grade: Not specified for this item.

General formulation research context (literature/general):

• OPSS‑PEG‑OPSS is used in research settings to prepare reducible PEGylated conjugates and crosslinked networks for preformulation and delivery studies, enabling controlled cleavage under reducing conditions.
• Utility in process development:
  • As a hydrophilic spacer, PEG can modulate solubility and colloidal stability of biomolecule conjugates during analytical characterization.
  • The pyridyl disulfide handle allows UV‑traceable coupling progress (A343) without additional labels, aiding in-process control.
• Manufacturing considerations (research only):
  • Control of molecular weight distribution and end‑group fidelity is essential for reproducible performance.
  • Residual pyridine‑2‑thione should be minimized by purification (dialysis/SEC) to meet internal quality targets.

Note: For research use only; not for drug, diagnostic, or therapeutic applications.

Physical Properties

Item-specific properties: Not specified for this item; refer to CoA/Spec Sheet.

Typical properties for OPSS‑terminated PEGs (literature/general):

• Physical state: Viscous liquid to waxy solid depending on PEG MW and dispersity.
• Solubility: High in polar organic solvents (DMF, DMSO, acetonitrile, alcohols); good to moderate in water depending on MW and end‑group loading. Aromatic/alkane solubility is limited but may be enhanced by OPSS end groups.
• pKa: Not applicable (neutral polymer); OPSS end groups are not ionizable in neutral water but can be protonated at very low pH (literature trend).
• LogP: Not defined for polymers; overall hydrophilicity dominated by PEG backbone.
• Optical handle: Release of pyridine‑2‑thione upon thiol coupling shows λmax ~343 nm (ε ~8,000 M−1 cm−1 in aqueous buffer; literature, values vary with conditions).
• Viscosity: Increases with MW and concentration (literature).

Notes:

• Melting point, boiling point, density, refractive index, moisture content, and exact molecular weight are batch‑ and MW‑dependent and are not provided for this catalog item.

Quality and Grades

Item-specific grade/purity and appearance: Not specified for this item; refer to CoA/Spec Sheet.

Context for bifunctional OPSS‑PEG quality (literature/general):

• Key QC attributes typically evaluated:
  • Number‑average molecular weight (Mn) and dispersity (Đ) by GPC/SEC relative to PEG standards.
  • End‑group functionality: >90–95% dual functionalization is commonly targeted; verified by 1H NMR end‑group integration and/or UV assay via pyridine‑2‑thione release after quantitative reaction with excess thiol.
  • Residual impurities: Solvent, water, unreacted small molecules, and pyridine‑2‑thione; assessed by NMR, HPLC/UPLC, and Karl Fischer where relevant.
  • Bioburden/endotoxin: Sometimes reported for bio‑oriented PEGs; not specified for this item.
• What grade means in practice:
  • For conjugation work, “bioconjugation” or “research” grade implies low residual small‑molecule contaminants and high end‑group fidelity for predictable coupling efficiency.
• Stabilizers:
  • OPSS end groups generally do not require added stabilizers when stored dry at room temperature away from light; reducing agents must be strictly excluded.
• Documentation: For project‑critical work, request batch CoA including end‑group assay and MW distribution.

Reaction and Applications

Manufacturer applications: Not specified for this item.

General applications for OPSS‑PEG‑OPSS (literature/general):

• Thiol–disulfide exchange bioconjugation:
  • Reacts selectively with free thiols on peptides, proteins, oligonucleotides (thiolated), and nanoparticles/surfaces to yield disulfide‑bridged conjugates (PEG–S–S–R), releasing pyridine‑2‑thione (A343).
  • Enables reducible linkages—stable extracellularly but cleavable by reducing agents (e.g., glutathione in reductive environments; literature concept).
• Crosslinking and hydrogel formation:
  • Bifunctional nature allows inter‑ or intramolecular crosslinking of thiolated polymers to form redox‑responsive networks and coatings.
• Surface modification:
  • Immobilization onto thiol‑functional gold or silica surfaces to create antifouling PEG brushes with disulfide anchors; useful in sensor passivation.
• Protein/particle spacing and stealthing (research use):
  • PEG spacer increases hydrodynamic size, reduces nonspecific interactions, and improves colloidal stability in biochemical assays.

Practical tips (literature):

• Work at pH 7.0–8.0; excessive basicity accelerates side reactions and hydrolysis of sensitive motifs.
• Degas buffers; include EDTA to suppress metal‑catalyzed thiol oxidation.
• Quantify coupling by monitoring A343 of released pyridine‑2‑thione; use extinction coefficient appropriate to your medium.
• Avoid reductants until after conjugation; if reduction is desired post‑coupling, apply stoichiometric control to avoid over‑reduction of product.

Reaction Conditions

Item-specific reaction parameters: Not specified for this item; refer to CoA/Spec Sheet.

Typical conditions for OPSS–thiol coupling (literature/general):

• Medium: Aqueous buffer (phosphate or HEPES) pH 7.0–8.0; or anhydrous DMSO/DMF stocks diluted into buffer.
• Concentration: 0.05–10 mM OPSS end groups, matched stoichiometrically to thiol equivalents.
• Temperature/time: 20–25°C, 15–120 min for most biomolecular thiols; more hindered substrates may require longer.
• Additives: 0.5–5 mM EDTA; oxygen removal by degassing. Avoid DTT/TCEP/β‑ME during coupling.
• Monitoring: Follow release of pyridine‑2‑thione at ~343 nm; calculate conversion using an extinction coefficient appropriate to the buffer/solvent system.
• Workup: Desalt by spin filtration, dialysis, or SEC to remove small‑molecule byproducts and excess reagent.

Stability considerations (literature):

• OPSS groups are stable when dry and protected from reducing agents. In aqueous media, slow background hydrolysis/thiol exchange can occur; prepare fresh solutions.
• Disulfide‑linked products can be cleaved deliberately with reductants (e.g., DTT) if reversible conjugation is desired.

Safety and Handling

Item-specific GHS data (signal word, H‑statements, pictograms, classification): Not specified for this item; refer to SDS.

General safety guidance for OPSS‑functional PEGs (literature/general):

• Hazards: May cause skin/eye/respiratory irritation. OPSS end groups react with free thiols; avoid contact with biological thiols (e.g., cysteine‑containing proteins) unless intended.
• Incompatibilities: Strong reducing agents (e.g., DTT, TCEP, β‑mercaptoethanol) will cleave OPSS groups; free thiols will consume functionality; strong oxidizers; strong bases/acids may degrade PEG over time.
• PPE: Lab coat, safety glasses, appropriate chemically resistant gloves (e.g., nitrile). Handle solutions in a fume hood to avoid aerosol/inhalation.
• Handling: Use dry, oxygen‑poor conditions if long workups are anticipated; include EDTA (0.5–5 mM) in aqueous buffers to chelate metals that catalyze thiol oxidation (literature practice). Avoid prolonged exposure to elevated temperatures.
• First aid (overview; defer to SDS):
  • Skin/eye contact: Rinse with water for 15 minutes; remove contaminated clothing; seek medical attention if irritation persists.
  • Inhalation: Move to fresh air; seek medical attention if symptoms occur.
  • Ingestion: Rinse mouth; do not induce vomiting; seek medical attention.
• Waste: Collect unused reagent/solutions as organic/halogen‑free waste per institutional and local regulations.

Solvent Selection

Item-specific solvent recommendations: Not specified for this item; refer to CoA/Spec Sheet.

General guidance for OPSS‑PEG‑OPSS (literature/general):

• Polarity and miscibility:
  • PEG backbone confers high polarity and hydrogen‑bond acceptance; readily soluble in water (especially lower MW) and polar aprotic solvents (DMSO, DMF, NMP, acetonitrile). Soluble in alcohols; limited solubility in nonpolar hydrocarbons.
• Choosing aqueous vs organic media:
  • Aqueous buffers (pH 7.0–8.0) are preferred for conjugation to biomolecule thiols; include 0.5–5 mM EDTA and degas to minimize thiol oxidation.
  • Anhydrous DMF/DMSO are useful for small‑molecule or surface thiol coupling, then dilute into the working buffer.
• Buffer selection notes:
  • Avoid thiol‑containing buffers/reagents (DTT, β‑ME, TCEP) during coupling—they consume OPSS groups.
  • Phosphate, HEPES, or acetate buffers at neutral to slightly basic pH are common; ionic strength can improve solubility for higher‑MW PEGs (literature).
• Quick comparison (literature):
  • DMSO: Maximum solubilizing power; fully compatible with OPSS; miscible with water for later dilution.
  • DMF: Similar to DMSO with lower viscosity; ensure low water content.
  • Water/PBS: Biocompatible; monitor pH and avoid reductants.
  • Alcohols: Useful for stock solutions; may affect biomolecule structure at higher percentages.

Storage and Reconstitution

Storage (item-specific):

• Storage Conditions: Room temperature (per product data).
• Shipped: Normal (per product data).

Additional guidance (general/literature; not item-specific specifications):

• Keep container tightly closed in a dry place, protected from light. Exclude moisture and reducing agents. If long-term storage is planned, consider inert atmosphere.
• For solution stocks, prepare in anhydrous DMSO/DMF or in buffer immediately before use; store chilled and use promptly. Aqueous solutions are less stable—prepare fresh.
• Do not add DTT, TCEP, β‑mercaptoethanol, or other thiols/reductants until after intended conjugation steps.

Reconstitution details (concentration, solvent, stability): Not specified for this item; refer to CoA/Spec Sheet.

Research Use Note: For research use only.

Structure and Identity

Item-specific identifiers (SMILES, InChIKey, CAS, MF, MW): Not specified for this item; refer to CoA/Spec Sheet.

General description (literature/general knowledge):

• OPSS-PEG-OPSS denotes a bifunctional poly(ethylene glycol) bearing terminal 2‑pyridyl disulfide (OPSS) groups at both ends of the PEG chain.
• Structural features:
  • Central, flexible, hydrophilic polyether backbone: –[CH2–CH2–O]n– (PEG).
  • Each terminus is capped with an OPSS (2‑pyridyl disulfide) moiety: –S–S–(2‑pyridyl).
  • The OPSS group undergoes thiol–disulfide exchange with free thiols (R–SH), forming a new disulfide bond (PEG–S–S–R) and releasing pyridine‑2‑thione (chromophore, λmax ~343 nm; literature).
• 2D structural description in words:
  • A linear PEG chain with ether linkages, flanked at both ends by aryl disulfide caps where each cap consists of a disulfide bridge connected to a 2‑pyridyl ring.
• Typical form:
  • Depending on PEG molecular weight (not specified here), the material may be a viscous liquid (low MW) or a waxy/solid (higher MW) (literature).

Synthetic Utility

General synthetic utility (literature/general):

• Functional group set: Two terminal 2‑pyridyl disulfides on a PEG scaffold provide orthogonal, thiol‑specific reactivity enabling:
  • Installation of disulfide‑linked PEG onto thiolated substrates (proteins, peptides, nanoparticles, polymers) under mild, aqueous conditions.
  • Formation of redox‑cleavable crosslinks between thiol‑bearing macromolecules to build responsive networks and hydrogels.
• Strategic roles in synthesis:
  • Temporarily mask thiols as disulfides with PEG for solubility enhancement and processing, then regenerate thiols by selective reduction.
  • Use as a spacer to control intermolecular distance and reduce steric congestion in multivalent constructs.
• Compatibility:
  • Operates at neutral pH and room temperature; tolerant of many functional groups except strong reductants and competing free thiols.
• Analytical benefit:
  • Coupling releases pyridine‑2‑thione, enabling stoichiometric monitoring and degree‑of‑substitution calculations by UV–vis without extra derivatization.

Item-specific reactivity specs and substitution ratios: Not specified for this item; consult CoA/Spec Sheet.

Target Specificity

Not applicable. This product is a chemical linker/reagent, not a biological targeting agent. No antigen/epitope, clone, isotype, or species reactivity information is provided for this item.

Foire aux questions

How should this product be stored?

Store at room temperature.

How is this product shipped?

This product ships under standard ambient conditions. No temperature-controlled packaging is required.

What documentation is provided?

Available product documentation, including Certificates of Analysis (COA), Safety Data Sheets (SDS), and specification sheets, is shown in the product document area. Document availability and access follow the current site policy.