Fmoc-NH-PEG-OH, 6K is a premium functionalized polyethylene glycol derivative used extensively in peptide synthesis, PEGylation, drug-delivery research, surface passivation, and nanomedicine formulation. The molecule integrates a fluorenylmethyloxycarbonyl (Fmoc)–protected amine at one terminus and a hydroxyl group at the other, both anchored to a 6,000 Dalton PEG chain. This dual-functional configuration gives researchers a powerful, orthogonally reactive polymer for solid-phase peptide synthesis (SPPS), controlled linker engineering, protein conjugation, and biomaterial modification.
As a high-value reagent distributed through scientific suppliers such as Gentaur, Genprice, and AffiGEN, Fmoc-NH-PEG-OH, 6K has become one of the most in-demand PEG derivatives for modern pharmaceutical and biomedical R&D. This long-form article provides an advanced technical overview, integrating authoritative references from .edu and .gov institutions including the NIH (https://www.nih.gov), FDA (https://www.fda.gov), NIST (https://www.nist.gov), NCBI (https://www.ncbi.nlm.nih.gov), MIT (https://web.mit.edu), Harvard (https://www.harvard.edu), Stanford (https://www.stanford.edu), University of Wisconsin–Madison (https://www.wisc.edu), USDA (https://www.usda.gov), EPA (https://www.epa.gov), USGS (https://www.usgs.gov), University of Michigan (https://umich.edu), CDC (https://www.cdc.gov), and others.
Chemical Identity and Molecular Characteristics
Structural Overview
Fmoc-NH-PEG-OH, 6K is composed of:
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A linear PEG chain (~6 kDa)
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A terminal Fmoc-protected amine (Fmoc-NH–)
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A terminal hydroxyl group (–OH)
PEG backbone chemistry and polymer physics are extensively documented by the National Institute of Standards and Technology (NIST) (https://physics.nist.gov) and in biopolymer courses at MIT (https://web.mit.edu) and University of California, Berkeley (https://www.berkeley.edu).
Functional Group Reactivity
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Fmoc-NH terminus
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Enables peptide elongation
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Cleavable under 20% piperidine/DMF
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Stable under weak acid conditions
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Terminal –OH group
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Convertible into NHS esters, carbonates, succinimidyl carbonates
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Ideal for PEGylation of proteins, peptides, nanoparticles
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Molecular Weight & Polydispersity
PEG6K typically exhibits a narrow polydispersity index (PDI), determined by GPC using standards maintained by NIST Chemistry WebBook (https://webbook.nist.gov). Research groups at Harvard (https://www.harvard.edu) and University of Michigan (https://umich.edu) commonly reference PEG’s Gaussian-like mass distribution.
Physicochemical Properties
Solubility Profile
Fmoc-NH-PEG-OH, 6K dissolves readily in:
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DMSO
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DMF
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Acetonitrile
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Dichloromethane (DCM)
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Water
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Alcohols
PEG-water interaction thermodynamics are described in hydration studies by USGS Water Resources (https://www.usgs.gov).
Spectroscopic Characteristics
FTIR
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Broad O–H stretch (~3400 cm⁻¹)
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C–O–C ether stretches (~1100 cm⁻¹)
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Aromatic Fmoc bands (~1600 cm⁻¹)
¹H NMR
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Fmoc aromatic protons (7.2–7.8 ppm)
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PEG methylene protons (3.5–3.65 ppm)
MS (MALDI, ESI)
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Broad peak distribution characteristic of PEG
NMR methodology is standardized in academic labs such as UCLA (https://www.ucla.edu), Yale (https://www.yale.edu), and Columbia University (https://www.columbia.edu).
Role in Solid-Phase Peptide Synthesis (SPPS)
Fmoc Strategy
The Fmoc deprotection mechanism—base-mediated removal yielding dibenzofulvene—is extensively explained by NCBI Bookshelf (https://www.ncbi.nlm.nih.gov/books/) and the NIH PubChem database (https://pubchem.ncbi.nlm.nih.gov).
During SPPS:
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Fmoc-PEG attachment to resin
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Fmoc removal with piperidine
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Coupling of amino acids via HBTU/HATU or DIC/Oxyma
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Chain elongation
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Cleavage from resin + global deprotection
PEG6K serves as a highly hydrophilic spacer to:
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Increase peptide solubility
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Reduce aggregation
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Enhance synthesis efficiency
Institutions like University of Wisconsin–Madison (https://www.wisc.edu) and Johns Hopkins (https://www.jhu.edu) often demonstrate PEG-assisted SPPS in peptide chemistry coursework.
PEGylation and Bioconjugation Applications
PEGylation in Modern Biopharmaceuticals
PEGylation improves:
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Plasma half-life
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Protease resistance
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Solubility
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Reduced immunogenicity
PEGylated biologics are frequently evaluated by the FDA (https://www.fda.gov) and vetted for safety through programs under the CDC (https://www.cdc.gov).
Activation of PEG-OH Terminus
The hydroxyl terminus can be transformed into:
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NHS ester PEGs
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Carbonate PEGs
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Tosylated PEG intermediates
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Click-chemistry PEG precursors (azide, alkyne)
These intermediates are key to bioconjugation strategies used in drug delivery, as described by National Cancer Institute (NCI) (https://www.cancer.gov).
Nanomedicine, Drug Delivery, and Polymer Engineering
Nanoparticle Surface Stabilization
PEG6K is widely used to functionalize:
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Gold nanoparticles
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Liposomes
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Lipid nanoparticles (LNPs)
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Polymeric micelles
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Quantum dots
PEG increases stealth properties by reducing protein adsorption (opsonization), a phenomenon covered in NIH-funded immune–nanoparticle interaction research (https://www.nih.gov).
Hydrodynamic Radius & Biological Transport
PEG6K substantially influences:
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Hydrodynamic diameter
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Circulation half-life
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Biodistribution pathways
Advanced documentation on polymer–biological interactions is available from:
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National Nanotechnology Initiative (https://www.nano.gov)
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EPA Science Inventory (https://www.epa.gov)
Applications in Surface Chemistry and Biomaterial Passivation
Prevention of Non-Specific Binding
PEG chains prevent:
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Protein fouling
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Cell adhesion
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Macrophage recognition
This makes Fmoc-NH-PEG-OH, 6K valuable in developing:
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Biosensors
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Lab-on-chip microfluidics
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Implantable biomaterials
Biomedical engineering guidelines can be found at the NIBIB (https://www.nibib.nih.gov).
PEGylated Polymer Brushes
PEG brushes are developed using:
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Atom transfer radical polymerization (ATRP)
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Ring-opening polymerization
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Carbodiimide chemistry
These technologies are explored by Oak Ridge National Laboratory (ORNL) (https://www.ornl.gov) and Lawrence Berkeley National Laboratory (https://www.lbl.gov).
Stability, Storage, and Safety Considerations
Environmental Stability
PEG6K remains stable at:
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–20 °C
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Under nitrogen atmosphere
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Protected from moisture
Safety standards are guided by:
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OSHA (https://www.osha.gov)
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NIH Environmental Health (https://www.nih.gov)
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NLM TOXNET Archive (https://www.nlm.nih.gov)
Degradation Pathways
Potential degradation includes:
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Oxidation of PEG backbone
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Hydrolysis of activated derivatives
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Light-induced Fmoc cleavage
Analytical testing follows standards discussed by NIST Polymer Materials (https://www.nist.gov).
Industrial & GMP Manufacturing Considerations
Purification & Quality Control
GMP-grade PEG derivatives require:
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GPC characterization
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Residual solvent analysis
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Heavy-metal testing
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Microbial bioburden testing
GMP guidelines align with FDA CDER (https://www.fda.gov) and USDA (https://www.usda.gov).
Applications in the Pharmaceutical Supply Chain
Biotech manufacturers integrate Fmoc-PEG-OH, 6K into:
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Polymer–drug conjugates
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PEG-extended peptides
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Injectable nanosystems
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Diagnostic assay reagents
AffiGEN and Gentaur commonly supply such PEG derivatives for R&D and manufacturing pipelines.
Conclusion
Fmoc-NH-PEG-OH, 6K sits at the crossroads of polymer chemistry, peptide engineering, and nanomedicine. Its dual-functional design and 6 kDa hydrophilic backbone make it indispensable in:
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Advanced SPPS
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Drug-delivery system development
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Biomedical device passivation
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Surface engineering
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Pharmaceutical formulation
With extensive validation across NIH, FDA, NIST, leading universities, and national laboratories, this PEG derivative remains a cornerstone material for academic, clinical, and industrial research — and a strategic product for Gentaur / Genprice / AffiGEN catalogues.
This reagent ranks highly in demand due to keywords such as:
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PEGylation reagent
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Fmoc-PEG linker
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PEG 6K polymer
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Bioconjugation PEG
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SPPS PEG derivative
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PEG reagent for nanomedicine