Overview
Hydrazide-PEG-Thiol is a heterobifunctional polyethylene glycol (PEG) derivative designed for advanced bioconjugation and material science applications. The hydrazide group (-CONHNH2) reacts selectively with aldehydes or ketones, while the thiol (-SH) enables covalent bonding with maleimides, gold surfaces, or other thiol-reactive groups. The PEG spacer enhances solubility, reduces immunogenicity, and provides steric flexibility in biomedical systems. This compound is synthesized through controlled PEGylation processes, ensuring consistent chain lengths and functional group availability. It is commonly used in pharmaceuticals, diagnostics, and nanotechnology due to its ability to bridge biomolecules with synthetic materials while maintaining bioactivity.
Physical and Chemical Properties
Hydrazide-PEG-Thiol exhibits properties derived from its PEG backbone and functional termini. The PEG chain length (e.g., 1k, 3.4k, 5k Da) dictates hydrodynamic volume and solubility, with longer chains offering higher water solubility and steric shielding. The thiol group is prone to oxidation, forming disulfide bonds unless stabilized with reducing agents like TCEP. The hydrazide group is nucleophilic, reacting rapidly with carbonyl groups under mildly acidic conditions (pH 4-6). The compound’s bifunctionality allows orthogonal conjugation strategies, making it ideal for multi-step labeling or crosslinking. FTIR and NMR spectroscopy are typically used to verify structure and purity.
Main Applications
In drug delivery, Hydrazide-PEG-Thiol links therapeutic payloads (e.g., antibodies, peptides) to carrier nanoparticles via hydrazone bonds, which are stable at physiological pH but cleavable in acidic tumor environments. The thiol end can simultaneously anchor the construct to gold nanoparticles or maleimide-functionalized surfaces. In diagnostics, it conjugates enzymes or fluorescent probes to substrates while minimizing nonspecific binding. The PEG spacer also reduces steric hindrance in immunoassays. Additionally, this compound is used to modify hydrogels for controlled drug release, where the thiol group participates in Michael addition reactions with vinyl sulfones or acrylates.
Safety and Storage
Hydrazide-PEG-Thiol requires careful handling due to its reactive thiol group, which can cause skin/eye irritation. Use PPE (gloves, goggles) and work in a well-ventilated area. The hydrazide moiety may form explosive hydrazine derivatives under strong oxidizing conditions; avoid contact with peroxides. For long-term stability, store aliquots at -20°C under argon or nitrogen, sealed with desiccants. Solutions should be prepared fresh or frozen at -80°C with 1-5% trehalose as a cryoprotectant. Monitor for oxidation (yellow discoloration) and check thiol activity via Ellman’s assay before critical experiments.
B2B Procurement Guide
When sourcing Hydrazide-PEG-Thiol, prioritize suppliers with GMP-compliant synthesis facilities for batch-to-batch consistency. Key specifications include PEG molecular weight (e.g., 2k, 5k Da), purity (HPLC >95%), and functional group substitution (typically >90%). Request COA with MALDI-TOF or NMR data. Bulk buyers should negotiate custom modifications, such as maleimide-protected thiols (for stability) or azide-PEG-hydrazide variants for click chemistry. Lead times vary: off-the-shelf products ship in 1-2 weeks, while custom syntheses may take 4-8 weeks. For research use, smaller vials (100mg-1g) from Sigma-Aldrich or Creative PEGWorks are cost-effective.