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NOF’s Polyethylene Glycols (PEGs) for Hydrogels

Tunable PEG Structures, Tunable Hydrogels

  • What’s Polyethylene Glycol (PEG)?

    PEG, –(OCH₂CH₂)ₙ–, is a low-immunogenicity, biocompatible polymer. It is highly soluble in water and widely used in injectable drugs and medical devices.

    Reference: A.-E. Segneanu et al., Polymers, 17, 2026 (2025) and references therein. doi:10.3390/polym17152026

    Drawing of a PEG chain, a repeating –(OCH₂CH₂)ₙ– unit, ending in a terminal functional group

  • Tunable PEG Structures

    • Number of branching units: 3, 4 or 8 arms
    • PEG length: total MW 5,000–40,000
    • Terminal functional groups

  • Tunable Hydrogel Properties

    • Gelation speed
    • Stiffness
    • Degradability
    • Swelling behavior

  • Hydrogel Applications

    • Medical devices
    • Surgical sealants and implants
    • Drug delivery
    • 3D bioprinting, and more

Molecular Network Formation

Hydrogel Formation of Multi-Arm PEGs

  1. Two 4-arm PEGs, one ending in green and one ending in pink terminal functional groups

    Two Multi-Arm PEGs

    Each PEG carries a different terminal functional group.

  2. Dual-barrel syringe holding one PEG solution in each barrel, joined at a single outlet

    Mixing

    Solutions of the two PEGs are combined.

  3. Network of 4-arm PEGs linked where green and pink terminal groups meet

    Network Formation

    The two terminal groups couple with each other and crosslink the PEG arms.

  4. Clear hydrogel molded into the letters NOF in a glass petri dish

    Hydrogel

    The crosslinked PEG network forms the hydrogel.

Crosslinking Chemistry

Various Terminal Functional Groups

The network forms when the terminal groups of two PEGs couple, so choose a pair that react with each other. Each card lists the reactive partners. The abbreviations appear in product names, for example SUNBRIGHT® PTE‑200SH.

Terminal group X

PEG–(OCH₂CH₂)ₙ–X: thiol, amine and norbornene

Thiol and amine

Thiol (SH)

SH end group: –O–CH₂CH₂–SH
  • Reactive with maleimides, acrylates, NHS esters, hydroximoyl chlorides, etc.

Amine (EA)

EA end group: –O–CH₂CH₂–NH₂
  • Reactive with NHS esters, acrylates, aldehydes, etc.
  • HCl salt is also available

Norbornene

  • Reactive with hydroximoyl chlorides, tetrazines, etc.
  • Conjugation to thiols with a photoinitiator and light
  • High bioorthogonality

NB

NB end group: –O–CH₂CH₂– bonded to the nitrogen of a norbornene dicarboximide

NB2

NB2 end group: –O–(CH₂)₃–NH–CO– amide bonded to a norbornene ring

NB3

NB3 end group: –O–CO– ester bonded to a norbornene ring

Terminal group Y

PEG–(OCH₂CH₂)ₙ–Y: NHS ester, hydroximoyl chloride, maleimide, aldehyde and acrylate

NHS ester

  • Reactive with amines, thiols, etc.
  • Reactivity: CS > TS > GS > HS
  • Stability: HS > GS > TS > CS

CS

CS end group: succinimidyl succinate ester, –O–CO–CH₂CH₂–CO–O–NHS

TS

TS end group: succinimidyl carbonate, –O–CO–O–NHS

GS

GS end group: succinimidyl glutarate ester, –O–CO–(CH₂)₃–CO–O–NHS

HS

HS end group: –O–(CH₂)₅–CO–O–NHS, a succinimidyl hexanoate

Hydroximoyl chloride

  • Precursor for nitrile oxide
  • Reactive with norbornenes, alkynes, thiols, amines, isocyanides, etc.
  • High bioorthogonality

HM

HM end group: phenyl ether carrying a hydroximoyl chloride, –O–C₆H₄–C(Cl)=N–OH

HM3

HM3 end group: benzoate ester carrying a hydroximoyl chloride, –O–CO–C₆H₄–C(Cl)=N–OH

Maleimide

  • Reactive with thiols
  • Reversibly reactive with furans for constructing self-healing materials

MA2

MA2 end group: –O–CH₂CH₂–NH–CO–CH₂CH₂– bonded to a maleimide

Aldehyde

  • Reactive with amines

AL2

AL2 end group: –O–CH₂CH₂–CHO

Acrylate

  • Reactive with thiols and amines
  • Radical polymerization is possible

AR

AR end group: acrylate ester, –O–CO–CH=CH₂

Other end groups

The catalog also lists p‑nitrophenyl carbonate (NP) PEGs and more amine and maleimide variants. Flexible custom synthesis is available for specific requirements.

View all PEGs for hydrogels

SUNBRIGHT® Multi-Arm PEGs

Various Branching Architectures

Each arm ends in a terminal functional group, shown as X. Total molecular weights range from 5,000 to 40,000.

3-arm PEGs

3-arm PEG with three PEG arms on a glycerine core, each ending in X

SUNBRIGHT® GL series

Glycerine, tri-polyethylene glycol ether

4-arm PEGs

4-arm PEG with four PEG arms on a pentaerythritol core, each ending in X

SUNBRIGHT® PTE series

Pentaerythritol, tetra-polyethylene glycol ether

View 4-arm Functional PEG Series

8-arm PEGs

8-arm PEG with eight PEG arms on a hexaglycerine core, each ending in X

SUNBRIGHT® HGEO series

Hexa-glycerine, octa-polyethylene glycol ether

View 8-arm Functional PEG Series

High-Purity 8-Arm PEGs

SUNBRIGHT® DX Series

NOF’s 8-arm PEGs with high polymer purity and a narrow polydispersity.

View SUNBRIGHT® DX Series

Features

  • High polymer purity
  • Narrow polydispersity: ca. 1.02, compared with ca. 1.12 for a conventional 8-arm PEG (HGEO series)
SUNBRIGHT DX series structure: two branched cores joined by an –OCH₂CH₂CH₂CH₂O– linker, each carrying four PEG arms that end in X

Conventional 8-arm PEG

Chromatogram of a conventional 8-arm PEG with a broader main peak

HGEO series

Polydispersity: ca. 1.12

NOF’s 8-arm PEG

Chromatogram of the SUNBRIGHT DX series with a single sharp, narrow peak

SUNBRIGHT® DX series

Polydispersity: ca. 1.02

Key finding

SUNBRIGHT® DX series has a narrower molecular weight distribution than a conventional 8-arm PEG, with a polydispersity of about 1.02 versus 1.12.

Partner with NOF

Why Choose NOF?

  • GMP manufacturing at qualified facilities in Japan
  • Extensive experience with customer audits
  • High-quality production from lab to commercial scale
  • Used in numerous marketed drugs and clinical trials
  • Design and optimization of scalable, robust synthetic routes
  • Fully synthetic and free from BSE and TSE risk
  • Proven regulatory support and responsive technical support
  • Flexible custom synthesis for specific requirements

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