≥95% for sensitive chromatographic and analytical workflows requiring minimal baseline interference.
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Storage & shipping
Store at -20°C Ships Ice chest + Ice pads Check lot-specific COA for exact specifications.
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Quality documents
SDS, COA, datasheet, and spec sheet available for download. Lot-specific COA accessible via lot number lookup.
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Literature proof
Cited in 0 peer-reviewed publications across chromatography, organic synthesis, and cross-coupling reactions.
Panoramica
Thiol-PEG12-acid is a PEG derivative containing a thiol group and a terminal carboxylic acid. The hydrophilic PEG spacer increases solubility in aqueous media. The thiol group reacts with maleimide, OPSS, vinylsulfone and transition metal surfaces including gold, silver, etc. The terminal carboxylic acid can be reacted with primary amine groups in the presence of activators (e.g. EDC, or DCC) to form a stable amide bond.
This compound belongs to the class of organic compounds known as carboxylic acids. These are compounds containing a carboxylic acid group with the formula -C(=O)OH.
External Descriptors
Not available
1. Djoumbou Feunang Y, Eisner R, Knox C, Chepelev L, Hastings J, Owen G, Fahy E, Steinbeck C, Subramanian S, Bolton E, Greiner R, and Wishart DS. ClassyFire: Automated Chemical Classification With A Comprehensive, Computable Taxonomy. Journal of Cheminformatics, 2016, 8:61.
Clean Au substrate; immerse in 0.1–1 mM ethanolic solution of Thiol‑PEG12‑acid (degassed), 12 h, RT.
Rinse, dry under N2; activate terminal –COOH in situ with EDC/NHS for amine coupling.
Note: These are literature-style examples, not validated, item-specific protocols. Optimize conditions empirically.
Biological Roles
This product is a synthetic bifunctional linker rather than a native metabolite.
General notes (literature/general)
Function in bioconjugation: Thiol‑PEG12‑acid serves as a hydrophilic spacer to separate functional cargo from surfaces or biomolecules, reducing steric hindrance and nonspecific interactions. The PEG chain can improve aqueous solubility and reduce protein adsorption.
Nonbiogenic character: PEG backbones are not natural biopolymers; biological processing varies by system. Terminal –COOH and –SH groups participate in standard covalent chemistries (amide formation, Michael addition), but the polymeric backbone is generally inert biologically.
In vitro utility: Frequently used to present carboxyl groups on thiol-binding surfaces (e.g., gold) for subsequent immobilization of peptides, enzymes, or antibodies via EDC/NHS coupling, or conversely to introduce thiols onto amine-bearing biomolecules after prior activation of the acid.
Item-specific biological data
Not specified for this item; no claims are made regarding cellular uptake, metabolism, or in vivo behavior. For research use only.
Buffer Applications
This is not a classical buffering agent. However, buffer choice is critical for its coupling chemistries (literature/general):
EDC/NHS coupling of –COOH: Use MES (pH 5.0–6.5) or phosphate (pH 6.0–7.4). Avoid primary amine buffers (Tris, glycine) during activation to prevent side reactions. Typical ionic strength 50–200 mM.
Thiol–maleimide coupling: pH 6.5–7.5 in phosphate or HEPES buffers maintains thiol in reactive yet not overly deprotonated state, limiting maleimide hydrolysis.
Metal chelation: Include 0.5–2 mM EDTA to suppress metal-catalyzed thiol oxidation when compatible.
Oxygen control: Degas buffers (N2 sparge or vacuum/N2 cycles) to slow thiol oxidation. Prepare fresh immediately before use.
Item-specific buffer capacity/specs
Not applicable; this product does not itself buffer solutions. Verify coupling efficiency in your chosen buffer by small-scale trials.
Green Alternatives
Context (literature/general)
The PEG12 backbone is water-compatible and often enables aqueous or water-rich processes, reducing reliance on chlorinated solvents. However, synthesis and downstream processing can still involve DMF, DCM, and other less-green media.
Greener choices and practices
Solvent selection: Prefer water, ethanol, or isopropanol for washing/assembly when feasible (e.g., Au–S SAM formation in ethanol/water). For carbodiimide couplings, use aqueous MES or phosphate buffers; minimize DMF/DMSO cosolvent percentages.
Alternative linkers: Polyglycerol- or polysarcosine-based hydrophilic spacers can offer improved biodegradability and reduced immunogenicity relative to PEG in some contexts (literature). Tradeoff: Different reactivity/availability and altered hydrodynamic profiles.
Greener activations: Use EDC with NHS or sulfo-NHS in buffered water instead of acid chlorides or carbodiimides in chlorinated solvents. Consider enzymatic ligations (e.g., sortase, transglutaminase) when compatible with substrates to avoid carbodiimides entirely.
Process intensification: Employ micro-scale or flow coupling to reduce reagent excess and waste. Use in situ degassing (vacuum/N2 cycling) instead of chemical oxygen scavengers when possible.
Tradeoffs
Aqueous work increases thiol oxidation risk; counter with inert atmosphere and minimal headspace. Ethanol is greener than acetonitrile or DCM but may slow SAM ordering; slight heating or longer times can compensate. Always validate performance versus standard conditions.
Pharmaceutical Uses
No clinical/therapeutic claims are made. For research and process development contexts only.
Literature/general formulation roles
Excipient/linker: Thiol‑PEG12‑acid can function as a spacer in conjugation of actives to carriers (proteins, nanoparticles) during preclinical research, offering increased hydrophilicity and tunable spacing.
Surface modification: PEGylation of device or particle surfaces to reduce nonspecific adsorption in formulation development studies.
Regulatory and compendial status
Pharmacopeial listing: Not specified for this item; refer to CoA/Spec Sheet. PEG oligomers and end-capped derivatives may not have monographs.
Impurity considerations: Free thiol vs disulfide content, residual solvents, and peroxides are key attributes to monitor for suitability in sensitive applications.
Manufacturing notes
For process development, document lot traceability and perform orthogonal identity testing (NMR, MS). Establish acceptance criteria for free –SH content and moisture. Any use in finished products would require comprehensive safety and regulatory assessment beyond the scope of this research-grade listing.
Physical Properties
Item-specific (from Product Data)
Appearance: Not specified for this item; refer to CoA/Spec Sheet.
Molecular weight: Not specified for this item; refer to CoA/Spec Sheet.
Literature/general values and expectations (for PEG12 thiol–acid linkers; non-spec)
Physical state: Typically a waxy solid or viscous syrup at ambient temperature for PEG chains in the PEG12 range.
Solubility: Highly soluble in polar protic and aprotic solvents (water, methanol, ethanol, DMSO, DMF) and miscible with many glycol-compatible media; limited solubility in nonpolar hydrocarbons (literature, general PEG behavior).
Acid–base properties: Terminal –COOH pKa typically ~4–5 in water; thiol pKa typically ~8–10 depending on local environment (literature ranges; actual value depends on exact end-group and microenvironment).
Partitioning: PEG backbones are hydrophilic; logP for PEGylated small molecules decreases with repeat number; PEG12 analogs are generally water-wettable (literature trend; not an item-specific spec).
Thermal behavior: PEG oligomers often show broad, ill-defined melting transitions and glass-transition behavior; decomposition occurs before classic “boiling” under ambient pressure (literature trend).
Refractive index/density: Not specified for this item; refer to CoA/Spec Sheet.
Notes
The thiol end is air-oxidation sensitive; apparent properties can change if partial disulfide formation occurs. Verify by analytical methods (Ellman’s assay, LC–MS) prior to use.
Quality and Grades
Item-specific (from Product Data)
Grade/purity: Not specified for this item; refer to CoA/Spec Sheet.
Guidance for this class of material (literature/general)
Typical offerings: PEG linkers are often provided at synthetic (research) grade with assay by 1H NMR and LC–MS. Some vendors provide enhanced “bioconjugation grade” materials with tighter controls on moisture, residual solvents, and free thiol content (verified by Ellman’s assay) and low peroxide content.
End-group integrity: For thiol-terminated PEGs, the critical quality attribute is the fraction of free –SH vs disulfide. Request an assay for free thiol content and residual disulfide percentage.
Metal and peroxide limits: Not specified for this item; refer to CoA/Spec Sheet. For sensitive applications (Au-surface SAMs, protein conjugation), low metal/peroxide background is desirable to minimize oxidation and side reactions.
Water content: Not specified for this item; refer to CoA/Spec Sheet. PEGs are hygroscopic; Karl Fischer values help gauge drying requirements pre-coupling.
Stabilizers: Not specified for this item; refer to CoA/Spec Sheet. If present, common stabilizers include trace antioxidants; confirm compatibility with your application.
Documentation checklist: CoA should ideally report identity (NMR, MS), assay/purity, free thiol content, residual solvents, and recommended storage. If performing regulated work, request lot-specific analysis and TSE/BSE/GMO statements as needed.
Reaction and Applications
Applications for a thiol–acid PEG12 linker (literature/general)
Bioconjugation spacer: The –COOH terminus can be activated (e.g., EDC/NHS) to couple to primary amines on biomolecules or surfaces; the –SH terminus then targets maleimide/haloacetyl handles via Michael addition/SN2, or binds to Au/Ag surfaces for immobilization.
Surface chemistry: Formation of self-assembled monolayers (SAMs) on gold via Au–S bonds. Mixed SAMs with inert methoxy-PEGs can modulate density and present terminal –COOH for further derivatization.
Nanomaterials: Ligand exchange on AuNPs/AgNPs to impart colloidal stability and introduce carboxyl functionality for subsequent EDC/NHS coupling to peptides, dyes, or polymers.
Polymer/gel modification: Introduction of thiol handles into hydrogels, or carboxyl handles into thiol–ene networks. Useful in hydrogel crosslinking (thiol–ene photochemistry) and post-gel functionalization.
Click strategies: Thiol–maleimide Michael addition (fast at pH 6.5–7.5), radical thiol–ene additions (UV with photoinitiator), and disulfide exchange for reversible linkages.
Practical tips
Control oxidation: Degas solutions; include reducing agents compatible with the chemistry (e.g., TCEP for aqueous work; avoid DTT if it competes with the coupling target). Store and handle under N2/Ar.
Sequence planning: Activate –COOH first (in mildly acidic buffer), quench excess activators, then perform thiol conjugation under near-neutral conditions. Alternatively, protect the thiol (e.g., as trityl/acetylthio) for multistep synthesis.
Analytics: Verify coupling by LC–MS, MALDI, or gel-shift (for proteins); assess free –SH with Ellman’s reagent to ensure integrity prior to maleimide coupling.
Reaction Conditions
Typical conditions (literature/general; adjust per substrate)
EDC/NHS activation of –COOH: Dissolve Thiol‑PEG12‑acid (1 eq) in MES buffer (50–100 mM, pH 5.5–6.0). Add EDC (1.1–2.0 eq) and NHS or sulfo‑NHS (1.1–2.0 eq). Stir 15–30 min at room temperature under N2. Couple immediately to amine-bearing target in pH 7.0–7.4 buffer for 1–2 h. Avoid Tris/glycine during activation.
Thiol–maleimide conjugation: pH 6.5–7.2 in phosphate or HEPES, 20–25°C, 0.5–2 h. Use 1.1–1.5 eq maleimide partner. Optional 0.5–1 mM TCEP to maintain –SH (avoid excess which can consume maleimide). Protect from light/oxygen.
Thiol–ene photochemistry: Organic or aqueous-organic media (EtOH, DMF, or buffer/EtOH), photoinitiator (e.g., LAP/Irgacure), 365–405 nm irradiation, minutes to hours depending on substrate and intensity. Maintain inert atmosphere.
Gold surface assembly: 0.1–1 mM in ethanol (degassed), immerse clean Au for 2–24 h at RT. Rinse with ethanol and water. For mixed SAMs, co-adsorb with methoxy-PEG-thiol at defined ratios.
Expected outcomes
EDC/NHS couplings typically give high conversions with amines bearing minimal steric hindrance; monitor by MS/HPLC. Maleimide additions proceed rapidly with high selectivity for thiols at near-neutral pH.
Notes
These conditions are general guidance from literature and are not item-specific specifications. Optimize for your system.
Safety and Handling
Item-specific (from Product Data)
GHS classification, signal word, pictograms, and H-statements: Not specified for this item; refer to SDS.
Storage conditions: Store at −20°C.
Shipping: Ice chest + ice pads.
Research use: For research use only.
General safety guidance (literature/general)
Primary hazards: Free thiols can oxidize to disulfides and may have a noticeable thiol odor. PEG backbones are generally regarded as low acute toxicity, but end-groups define reactivity.
Incompatibilities: Avoid strong oxidizers (may consume –SH), strong bases over prolonged times (thiolate formation/side reactions), and carbodiimides in the presence of unprotected nucleophiles unless coupling is intended. Trace transition metals catalyze thiol oxidation; use metal-free plasticware or add EDTA (0.5–2 mM) where compatible.
Handling: Work under inert gas (N2/Ar) for thiol-critical applications. Use dry, oxygen-free solvents. Keep containers tightly closed; minimize headspace oxygen. Prepare fresh solutions immediately prior to coupling.
PPE: Lab coat, safety glasses, and appropriate chemical-resistant gloves (nitrile). Use in a fume hood when weighing/handling powders or organic solutions.
First aid (overview; defer to SDS): Eye/skin contact—rinse with water for 15 minutes, remove contaminated clothing; inhalation—move to fresh air; ingestion—rinse mouth, seek medical advice. Provide SDS to medical personnel.
Waste: Collect solutions and rinses containing carbodiimides, NHS esters, or heavy metals as hazardous organic waste according to institutional and local regulations.
Solvent Selection
General guidance for Thiol‑PEG12‑acid (literature/general)
Polarity/miscibility: The PEG12 backbone confers high polarity and hydrogen-bond acceptor capacity. The material is typically soluble in water, alcohols (MeOH, EtOH), polar aprotics (DMF, DMSO, NMP, acetonitrile), and glycols. Solubility in nonpolar solvents (hexanes, toluene) is poor to moderate and improves with small amounts of polar co-solvent.
Aqueous work: For carbodiimide (EDC/NHS) activation of the acid toward amines, aqueous buffers (MES, phosphate) at pH ~5.5–7.4 are commonly used; ensure oxygen control to protect the thiol (degassing, nitrogen overlay) and consider adding 0.5–2 mM EDTA to suppress metal-catalyzed oxidation.
Anhydrous work: For NHS ester formation or acid chloride generation, use dry DMF, DCM, or THF under inert atmosphere. For thiol–maleimide coupling in organic media, dry DMF/DMSO are typical.
Gold/surface assembly: For self-assembled monolayers (SAMs) on Au, ethanol or ethanol/water mixtures are often preferred; remove dissolved oxygen by sparging or freeze–pump–thaw cycles.
Comparison notes (literature)
Versus shorter PEGs (PEG4/PEG6): PEG12 offers longer spacing and improved aqueous solubility but may increase hydrodynamic radius and reduce packing density on surfaces.
Versus non-PEG alkyl linkers: PEG12 improves water compatibility and reduces nonspecific binding but is less suited to strictly hydrophobic matrices.
Item-specific solvent constraints
Not specified for this item; verify compatibility with your substrates and refer to CoA/SDS for restrictions.
Storage and Reconstitution
Item-specific (from Product Data)
Storage conditions: Store at −20°C.
Shipping: Ice chest + ice pads.
General best practices (literature/general)
Atmosphere: Store under inert gas (N2/Ar) in a tightly sealed, dry container with desiccant to minimize moisture uptake and thiol oxidation.
Light/oxygen: Protect from light and minimize headspace oxygen. Consider aliquoting into small vials to avoid repeated air exposure.
Freeze–thaw: Avoid repeated freeze–thaw cycles; thaw only what is needed immediately before use.
Reconstitution
Solvents: Use freshly dried, oxygen-free solvents (e.g., anhydrous DMF, DMSO, ethanol, or degassed buffers) depending on the intended chemistry.
Concentration: Prepare working solutions at 1–100 mM as required by your application. For aqueous solutions intended for thiol chemistry, include 0.5–1 mM TCEP if compatible to maintain free –SH.
Filtration: If particulate matter is observed, clarify with 0.22 µm PTFE filter in organic media or PES in aqueous media.
Stability notes
The free thiol is susceptible to air oxidation to disulfide, especially in neutral/alkaline aqueous solutions. Prepare solutions immediately prior to use and verify free –SH content (e.g., Ellman’s assay) for sensitive conjugations.
Specifications
Any item-specific stabilizers, water content, or shelf life: Not specified for this item; refer to CoA/Spec Sheet.
Structure and Identity
Item-specific (from Product Data)
Product name: Thiol-PEG12-acid (SKU: T597505)
CAS: 1032347-93-5
CID: 75535053
InChIKey: 170179
SMILES: 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.
General structural description (literature/general)
Functional motif: A bifunctional polyethylene glycol (PEG) spacer with a terminal free thiol (–SH) on one end and a terminal carboxylic acid (–COOH) on the other.
Spacer length: “PEG12” denotes twelve ethylene glycol repeat units, i.e., –(CH2–CH2–O)12–, conferring hydrophilicity, flexibility, and ~4–5 nm end-to-end contour length in extended conformations (literature, approximate and conformation-dependent).
2D/features in words: One terminus presents a nucleophilic/soft thiol suitable for Michael addition or Au–S coordination; the opposite terminus presents a Brønsted-acidic carboxyl group amenable to carbodiimide activation and amide coupling. The interior comprises ether oxygens capable of hydrogen bonding and metal coordination.
Stereochemistry: None (achiral, no stereocenters in the PEG backbone).
Typical connectivity (schematic): HS–(CH2–CH2–O)12–CH2–CO2H (exact atom count/vendor architecture may vary by supplier; verify on CoA).
Synthetic Utility
Functional group reactivity (literature/general)
Carboxylic acid terminus: Amenable to carbodiimide (EDC/DIC) activation to form NHS esters, coupling to primary amines to yield amides. Can form acid chlorides (e.g., oxalyl chloride) for further derivatization when water-free conditions are used.
Thiol terminus: Undergoes Michael addition to maleimides, acrylates, and vinyl sulfones; SN2 alkylation with haloacetyl reagents; radical thiol–ene addition across terminal alkenes; and reversible disulfide formation/reshuffling.
Linker value
PEG12 spacing: Provides hydrophilic, flexible separation between conjugation partners, mitigating steric hindrance and enhancing accessibility to active sites on proteins or surfaces. Useful in mixed-monolayer strategies where spacing and hydration layers are critical.
Protecting group strategies
Thiol protection (e.g., trityl, acetylthio) facilitates multistep syntheses where the acid is first derivatized. Deprotection under mild acidic or nucleophilic conditions reveals the free thiol for the final coupling.
Analytical/QA
Characterize intermediates by 1H/13C NMR in D2O or CDCl3/CD3OD mixtures; confirm mass by ESI–MS/MALDI (PEG oligomers show characteristic 44 m/z spacing). Quantify free thiol by Ellman’s reagent. Monitor coupling by HPLC/UPLC with evaporative light scattering or MS detection due to weak UV absorbance of PEG backbones.
Target Specificity
Not applicable. This product is a small-molecule linker, not an antibody, enzyme, or biological targeting reagent. It does not possess inherent biochemical target specificity. Any selectivity arises from the chemistry of its end groups (e.g., thiol reactivity with maleimides or Au surfaces, and carboxyl activation toward amines). Refer to Reaction & Applications and Synthetic Utility for relevant selectivity considerations.
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