pEG tiol de 8 brazos - MW 40000 Da

Cat. No.: A163150

GRADE & PURITY MW 40000 Da

Storage

Protegido de la luz,Almacenar a -20°C,Cargado con argón

Shipped In

Hielera + almohadillas de hielo

Descripción general

8 brazo Los derivados del PEG tienen múltiples grupos reactivos que pueden utilizarse para modificar proteínas, péptidos y otros materiales a través de sus grupos funcionales. La pEGilación puede aumentar la solubilidad y la estabilidad y reducir la inmunogenicidad de péptidos y proteínas. También puede suprimir la unión inespecífica de moléculas cargadas a las superficies modificadas. .

Specifications

Especificaciones y pureza

MW 40000 Da

Condiciones de almacenamiento de almacenamiento

Protegido de la luz,Almacenar a -20°C,Cargado con argón

Enviado en

Hielera + almohadillas de hielo

Propiedades químicas y físicas

• Solubilidad: Soluble in regular aqeous solution as well as most organic solvents
• Sensibilidad: Light sensitive

Application Protocols

Item-specific tested applications and conditions are not provided for this product. Not specified for this item; refer to CoA/Spec Sheet.

Note: While general procedures for hydrogel formation and thiol-based conjugations are described in other sections (Reaction Conditions, Reaction & Applications), no validated, product-specific protocols or QC-tested application ranges are claimed here.

Biological Roles

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

General considerations for PEG–thiols in bio-related research (literature/general):

• Bioinert backbone: PEG is widely used to reduce protein adsorption and cell adhesion due to its hydrophilicity and chain mobility, creating steric and hydration barriers at interfaces.
• Multivalency: An 8-arm architecture enables multivalent presentation of ligands (when thiols are coupled to bioactive groups), facilitating avidity-driven interactions in biochemical assays and sensor platforms.
• Bioconjugation handle: Thiol termini allow selective reaction with cysteine residues on proteins via maleimide chemistry under mild, near-physiological conditions, enabling pegylated conjugates or network formation around biomacromolecules.
• Redox responsiveness: Disulfide formation/cleavage provides reversible linkages sensitive to intracellular redox environments (e.g., glutathione-rich conditions), useful for designing redox-cleavable materials in vitro.
• Hydrogel matrix: Crosslinked PEG networks serve as biologically inert scaffolds for 3D cell culture, controlled by incorporating adhesion peptides or growth factor-binding motifs via thiol coupling.

Notes and limitations:

• No intrinsic buffering capacity or biological activity is expected; biological effects arise from conjugated ligands or physical properties of formed materials.
• Endotoxin/bioburden control is critical for cell-contact experiments; status for this item is Not specified for this item; refer to CoA/Spec Sheet.

Buffer Applications

This product is not a buffer reagent per se. However, its performance in aqueous buffers is central to its use in bioconjugation and hydrogel formation.

General guidance (literature/general):

• Compatible buffers: Phosphate (PBS, 10–50 mM), HEPES (10–50 mM). Avoid amine-containing buffers (e.g., Tris) when reacting with maleimides due to possible side reactions; carbonate buffers (pH 8.0–9.0) can accelerate Michael additions but increase oxidation risk.
• pH ranges: Preserve –SH at pH 6.5–7.5 for storage/short handling; promote reaction at pH 7.0–8.0 (maleimide) or 7.5–8.5 (acrylates/vinyl sulfones), balancing kinetics vs oxidation.
• Oxygen control: Degas buffers (N2/Ar sparge) and use freshly prepared, deionized water. Include 0.1–1 mM EDTA to chelate trace metals.
• Ionic strength: 100–150 mM NaCl maintains protein stability in conjugations; adjust as needed for gelation in microfabrication contexts.

Practical recipe example (illustrative, literature/general):

• 1× PBS, pH 7.4, degassed, 0.5 mM EDTA; dissolve 8-Arm PEG Thiol to 5–20 wt% for hydrogel precursors. Mix stoichiometric electrophile partner rapidly and cast; allow gelation at room temperature.

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

Green Alternatives

Context: 8-Arm PEG Thiol is often used in aqueous, room-temperature processes, which aligns well with green chemistry principles. Greener choices focus on solvent systems and complementary crosslinkers rather than replacing the PEG–thiol itself.

Greener options (literature/general):

• Aqueous-only workflows: Prefer water or buffered saline over aprotic dipolar solvents (DMSO/DMF). Use degassing instead of chemical reducing agents when feasible.
• Complementary partners: Use PEG–maleimide or PEG–vinyl sulfone crosslinkers that react efficiently with thiols at neutral pH, minimizing catalysts and energy input.
• Photochemistry: For thiol–ene gels, select water-soluble, low-toxicity photoinitiators (e.g., LAP) and LED sources (405 nm) to reduce energy and avoid UV where possible.

Comparison (general, qualitative):

• Water/buffer vs DMSO/DMF: Water minimizes environmental impact and simplifies waste handling; DMSO/DMF offer kinetic control but raise EHS concerns and require solvent recovery.
• Thiol–Michael vs radical curing: Michael additions proceed at ambient temperature without radical initiators; radical thiol–ene can avoid amines/catalysts but may require light exposure.

Tradeoffs:

• Oxygen control is needed in water to prevent thiol oxidation; modest pH elevation (7.5–8.0) increases rate but also oxidation risk.
• Highly efficient electrophiles (maleimides) can hydrolyze; careful pH selection balances reactivity and stability.

Recommendation: Whenever possible, conduct crosslinking in degassed aqueous buffers at near-neutral pH, minimize organic cosolvent, and avoid heavy-metal catalysts.

Pharmaceutical Uses

No therapeutic or clinical claims are made. The following relate to formulation and manufacturing contexts (literature/general).

Roles for 8-arm PEG–thiols in pharma/bioprocess R&D:

• Excipient in materials: Formation of inert PEG-based hydrogels for in vitro formulation screening, depot matrices, or device coatings; can modulate mechanical properties and diffusion.
• Conjugation scaffold: Multivalent attachment of ligands, linkers, or targeting motifs via thiol chemistry to create defined macromolecular excipients or analytical standards.
• Surface treatment: Gold-binding thiols enable controlled PEGylation of medical device components or nanoparticle surfaces to reduce fouling during manufacturing analytics.
• Process aids: Star PEGs can serve as crowding agents or viscosity modifiers in development studies.

Regulatory/compendial notes:

• PEGs are widely described in pharmacopeias, but specific compliance (residual solvents, heavy metals, peroxides, endotoxin) depends on grade and supplier controls. For this specific item, compliance status is Not specified for this item; refer to CoA/Spec Sheet.

Caveats:

• Residual/reactive thiols must be fully reacted or controlled in finished devices/excipients to avoid unintended reactions.
• For any use approaching GMP, verify lot-specific data (Mn, PDI, functionality, bioburden/endotoxin) and perform risk assessments.

Physical Properties

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

General properties of 8-arm PEG–thiols (literature/general):

• Physical state: Typically a white to off-white solid or waxy solid at room temperature; may appear glassy or highly viscous depending on arm length (Mn).
• Solubility: Highly soluble in water and polar organic solvents (e.g., DMSO, DMF); soluble in alcohols; limited solubility in nonpolar solvents (e.g., hexane, toluene). Salt-containing aqueous buffers (PBS, HEPES) generally compatible.
• Hygroscopicity: PEG segments are hygroscopic; materials readily absorb moisture from air.
• Refractive index/viscosity: Increases with concentration and Mn; not a fixed value due to polydispersity.
• pKa: The terminal thiol pKa typically ~8–10 (literature, depends on linker microenvironment); deprotonation facilitates Michael addition but also accelerates oxidation.
• Thermal behavior: Glass-transition and softening temperatures depend on Mn; PEG lacks a sharp boiling point and decomposes before boiling under ambient pressure (polymeric).
• Oxidation: Thiols oxidize to disulfides; rate increases with pH, oxygen, and metal ions. PEG ether backbone is generally stable under neutral aqueous conditions.

Practical notes (general guidance):

• Prepare aqueous solutions with degassed, deionized water or buffer; include 0.1–1 mM EDTA to chelate trace metals when preserving –SH functionality.
• Minimize headspace oxygen and exposure to light to reduce thiol oxidation.

Quality and Grades

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

How quality is typically defined for multi-arm PEG–thiols (literature/general):

• Functionality: Verified number of reactive thiols per molecule (ideally ~8; measured via Ellman’s assay or NMR). Lot-to-lot certificates often report thiol content (meq/g) and percentage of full functionality.
• Molecular weight distribution: Reported as average Mn (and sometimes Mw, PDI = Mw/Mn) by GPC/SEC. Narrower PDI gives more predictable crosslinking behavior.
• Residuals: Monomer/solvent/metal residuals are usually controlled; low residual levels favor sensitive bioconjugations. Specific thresholds for this item are Not specified for this item; refer to CoA/Spec Sheet.
• Bioburden/endotoxin: For biofabrication or cell-contact applications, low bioburden/endotoxin grades are preferred. Status for this item is Not specified for this item; refer to CoA/Spec Sheet.
• Stabilization: Materials are commonly packaged under inert gas with desiccant; antioxidants are generally avoided to maintain bioconjugation performance unless declared. Any stabilizers for this item are Not specified for this item; refer to CoA/Spec Sheet.

What the grade implies (general):

• Research-grade PEG–thiols are suited for hydrogel formation, surface functionalization, and general synthesis. HPLC or “bioconjugation” grades emphasize low UV-absorbing impurities and better control of functionality, supporting optical and biological work.

Recommendation: Consult the item’s CoA for Mn, PDI, thiol content, residuals, and any applicable bioburden/endotoxin testing.

Reaction and Applications

Manufacturer applications: Not specified in Product Data.

General applications for 8-arm PEG Thiol (literature/general):

• Hydrogel crosslinking: Rapid network formation via thiol–Michael addition to multi-vinyl electrophiles (PEG–maleimide, –acrylate, –vinyl sulfone). Eight arms enable high crosslink density and tunable mechanics (storage modulus scales with functionality and concentration).
• Thiol–ene chemistry: UV- or thermal-initiated radical addition to norbornene/allyl substrates using photoinitiators (e.g., LAP, Irgacure 2959). Spatiotemporal control for patterning and microfabrication.
• Disulfide networking: Air oxidation or mild oxidants (e.g., H2O2 traces, ferricyanide) form reversible disulfide crosslinks for redox-responsive materials.
• Bioconjugation: Multivalent conjugation to maleimide-functional proteins/peptides, peptides bearing vinyl sulfones/acrylates, or surface immobilization on Au via Au–S bonds for biosensors and plasmonic nanostructures.
• Surface passivation: Dense PEG corona resists nonspecific adsorption; star topology improves grafting density on nanoparticles and flat substrates.

Practical tips:

• Preserve thiols: Degas solutions, include EDTA, and add TCEP (0.1–1 mM) just prior to coupling if necessary. Avoid amine buffers for maleimide reactions when possible (use phosphate) to limit competing hydrolysis.
• Stoichiometry: Target 1:1 thiol:electrophile equivalents (functional group basis). Account for functionality per macromer from CoA (meq/g).
• Curing control: For thiol–ene photogels, control dose (e.g., 365–405 nm, 5–20 mW/cm²) and initiator (0.05–0.5 wt%) to tune gelation kinetics and modulus.

Reaction Conditions

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

Typical conditions (literature/general):

• Thiol–maleimide conjugation: pH 6.8–7.4 in PBS or phosphate (10–50 mM), RT; reaction often completes within 5–60 min at 1–10 mM functional-group concentrations. Avoid excess amines; optionally include 0.1–0.5 mM EDTA. Maleimide hydrolysis increases >pH 7.5.
• Thiol–Michael (acrylates/vinyl sulfones): pH 7.5–8.5 in phosphate/HEPES or carbonate buffer; base catalysis (e.g., 0.01–0.1 equiv tertiary amine) can accelerate. Gel times span seconds–minutes depending on concentration and catalyst.
• Thiol–ene photopolymerization: Water with 0.05–0.5 wt% photoinitiator (e.g., LAP). Irradiate 365–405 nm, 5–20 mW/cm² for 10–120 s. Oxygen inhibition is modest for thiol–ene but degassing improves consistency.
• Disulfide formation: Air oxidation in pH 7–8 buffer over hours; accelerated by mild oxidants (e.g., 0.1–1 mM ferricyanide). Reversible with 1–10 mM TCEP or glutathione (in vitro).

Practical execution:

• Calculate stoichiometry on a functional-group basis using meq/g from CoA; target 1:1 thiol:electrophile for complete conversion.
• Prepare fresh, degassed solutions; combine components rapidly and cast or apply immediately to substrates.
• For protein conjugations, maintain protein stability (e.g., 100–150 mM NaCl, 0–4°C if needed) and avoid reducing agents that can cap maleimides.

Expected outcomes: High conversions (>90%, literature) under the above conditions when oxygen and pH are controlled.

Safety and Handling

Item-specific hazard classification: Not specified for this item; refer to SDS.

• Signal word, H-statements, GHS class, pictograms: Not specified for this item; refer to SDS.

General safety considerations (literature/general):

• Hazards: PEG backbones are of low acute toxicity; however, terminal thiols can be irritating and prone to oxidation. Dusts or powders may cause mechanical irritation to eyes/respiratory tract. Avoid inhalation of powders and contact with eyes/skin.
• Peroxide/oxidation concerns: Thiol termini readily oxidize to disulfides; handle under inert atmosphere when possible. PEG ethers can form peroxides upon prolonged exposure to air/UV, though the risk is lower than for low-MW ethers; periodic evaluation is prudent for aged solutions.
• Incompatibilities: Strong oxidizers; bases at elevated pH promote thiol oxidation; transition-metal salts catalyze oxidation. Avoid copper and iron surfaces or use chelators.
• PPE: Lab coat, safety glasses, and appropriate chemical-resistant gloves (e.g., nitrile). Use local exhaust/hood when weighing or dissolving.
• First aid (overview; consult SDS): If inhaled, move to fresh air; if on skin or in eyes, rinse with water for ≥15 min; if ingested, rinse mouth and seek medical advice. Show SDS to healthcare provider.
• Handling tips: Work quickly with minimized air exposure. Use degassed buffers, keep solutions on ice for sensitive conjugations, and protect from light.

Always review the product-specific SDS before use and implement institutional risk assessments.

Solvent Selection

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

General solvent guidance for 8-arm PEG Thiol (literature/general):

• Polarity/miscibility: PEG arms confer high hydrophilicity. The macromer is typically readily soluble in water, PBS, HEPES, carbonate, and polar organics (DMSO, DMF, NMP). Limited solubility in nonpolar solvents (hexane, cyclohexane) and chlorinated solvents improves with temperature.
• Aqueous work: Use degassed, oxygen-poor buffers (sparged with N2/Ar). Maintain pH 6.5–7.5 to preserve –SH; pH 7.0–8.0 when promoting Michael additions (balance reactivity vs oxidation).
• Organic work: Anhydrous DMSO or DMF are excellent for maleimide/acrylate couplings to minimize hydrolysis of electrophiles. Add base (e.g., triethylamine) cautiously if needed; avoid strong base that accelerates thiol oxidation.
• Additives: 0.1–1 mM EDTA helps suppress metal-catalyzed oxidation. Reducing agents (e.g., TCEP) can be included immediately before use; avoid DTT in maleimide couplings due to competing reactivity.

Comparison (general):

• Water/buffer: Green, biocompatible; best for hydrogel formation and bio-conjugation. Must control oxygen and pH.
• DMSO/DMF: High solubility and kinetic control; consider toxicity and downstream removal.

Tip: Warm gently (e.g., 25–37°C) and vortex/sonicate to accelerate dissolution; filter (0.22 µm) if sterility is required.

Storage and Reconstitution

Item-specific storage and shipping (from Product Data):

• Storage: Store at −20°C, protected from light, argon charged.
• Shipping: Ice chest + ice pads.

General handling and reconstitution guidance (literature/general):

• Upon receipt: Allow container to warm to room temperature in a desiccator before opening to avoid moisture condensation. Open under inert atmosphere if possible.
• Protection: Keep tightly sealed under inert gas (Ar/N2). Include desiccant. Minimize headspace oxygen.
• Solution preparation: Dissolve in degassed water, PBS, HEPES, or anhydrous DMSO/DMF as appropriate. Typical working concentrations for gel precursors are 5–30 wt% (literature), depending on desired crosslink density. Filter sterilize (0.22 µm) for sterile work.
• Antioxidants/reductants: If necessary, add EDTA (0.1–1 mM) and prepare immediately before use. For preserving –SH, a small amount of TCEP can be added just prior to reaction; avoid long-term storage with reducing agents.
• Aliquoting: Prepare single-use aliquots; store frozen (−20°C) and protected from light. Avoid repeated freeze–thaw cycles.
• Stability: Thiols can slowly oxidize even when frozen; verify free –SH content (e.g., Ellman’s assay) for critical applications.

Disposal: Follow institutional guidelines for disposal of PEG-containing and thiol-bearing materials; segregate organic solvent wastes when used.

Structure and Identity

Item-specific identifiers (from Product Data):

• Product name: 8-Arm PEG Thiol (SKU: A163150)
• CAS: Not specified for this item; refer to CoA/Spec Sheet.
• InChIKey / SMILES: Not applicable for polydisperse PEG macromolecules; Not specified for this item; refer to CoA/Spec Sheet.
• Molecular formula and exact molecular weight: Not specified for this item; refer to CoA/Spec Sheet. (Note: multi-arm PEGs are typically reported by average Mn.)

General structure (literature/general):

• Architecture: An 8-arm, star-shaped polyethylene glycol (PEG) macromer with each arm terminating in a free thiol (–SH) group.
• Core: Typically a multifunctional hub (e.g., hexaglycerol, pentaerythritol, or other polyol) from which eight PEG chains radiate. Exact core for this item is Not specified for this item; refer to CoA/Spec Sheet.
• Arms: Each arm consists of repeating –CH2–CH2–O– units (PEG). Degree of polymerization per arm determines average molecular weight; distribution is polydisperse by nature.
• Functional groups: Terminal thiols (–SH) enable Michael-type addition (to maleimides, acrylates, vinyl sulfones), thiol–ene radical additions, disulfide formation, and chemisorption to gold surfaces.
• Stereochemistry: PEG backbones are achiral; no defined stereocenters. Multi-arm topology is constitutional, not stereochemical.
• 2D description: A central node linked by eight ether chains (–(CH2–CH2–O)n–) ending in –CH2–CH2–SH or –(linker)–SH moieties; no aromatic rings.

Notes:

• Because multi-arm PEGs are polymers, conventional single-molecule identifiers (SMILES/InChI) are not uniquely defined; specifications are typically given as average Mn/Mw and arm functionality.

Synthetic Utility

General synthetic roles of 8-Arm PEG Thiol (literature/general):

• Multifunctional crosslinker: Eight –SH termini enable rapid formation of 3D polymer networks with di- or multi-functional electrophiles (acrylates, vinyl sulfones, maleimides), providing control over gel point, modulus, and mesh size.
• Modular macromolecular scaffold: Orthogonal conversion of thiols to thioethers, thioesters, thio-carbamates allows attachment of dyes, peptides, or linkers, creating dendritic conjugates with defined multivalency.
• Click-chemistry partner: Engages in thiol–Michael and thiol–ene “click” reactions that are high-yielding, tolerant of water and biomolecules, and proceed under mild conditions.
• Redox-chemistry handle: Reversible disulfide formation enables temporary protection or stimuli-responsive linkages; reduction (e.g., with TCEP) regenerates –SH.
• Surface/layer construction: Strong Au–S chemisorption provides dense PEG layers on gold, enabling SAMs with anti-fouling tails; 8-arm topology increases surface coverage per molecule.

Retrosynthetic/strategic considerations:

• Use arm length (Mn/arm) to tune hydrodynamic radius and spacing between attachment points; higher Mn affords larger mesh sizes and lower crosslink density at equal wt%.
• Account for polydispersity and functionality efficiency when calculating stoichiometry; use meq/g from CoA.
• Preserve orthogonality: Perform thiol-specific steps before introducing nucleophiles that might compete at Michael acceptors.

Target Specificity

This product is not an antibody or affinity reagent. No target specificity, epitope, clone, or isotype information applies.

Item-specific immunoassay details: Not applicable; not provided in Product Data.