Overview
MAL-PEG-PH-CHO is a heterobifunctional crosslinker designed for bioconjugation applications. Its structure combines a maleimide group (MAL) for thiol-specific reactions, a polyethylene glycol (PEG) spacer for improved solubility and biocompatibility, a phenyl (PH) group for stability, and an aldehyde (CHO) terminus for amine coupling. This compound is particularly valuable in pharmaceutical and biomedical research, where precise protein modification and drug delivery systems are critical. The PEG spacer reduces steric hindrance and minimizes immune responses, making it ideal for therapeutic applications like antibody-drug conjugates (ADCs). The aldehyde group enables stable Schiff base formation with lysine residues or other primary amines, while the maleimide reacts selectively with cysteine thiols under mild conditions.
Physical and Chemical Properties
MAL-PEG-PH-CHO is typically supplied as a white to off-white powder or solid, soluble in water and organic solvents like DMSO or DMF. Its molecular weight varies depending on the PEG chain length (commonly 1,000-5,000 Da). The maleimide group is sensitive to hydrolysis, especially at high pH, while the aldehyde group is reactive toward nucleophiles such as amines and hydrazides. The PEG component enhances hydrophilicity, reducing aggregation and improving biocompatibility. The phenyl group adds structural rigidity, which can stabilize the linker in complex conjugates. Storage at -20°C under anhydrous conditions is recommended to preserve reactivity, as moisture and light can degrade the maleimide and aldehyde functionalities.
Main Applications
MAL-PEG-PH-CHO is widely used in bioconjugation for creating antibody-drug conjugates (ADCs), where it links cytotoxic drugs to antibodies via thiol and amine groups. Its PEG spacer prolongs circulation time in vivo and reduces immunogenicity, critical for therapeutic efficacy. In diagnostics, it aids in fluorescent or enzyme labeling of proteins for assays. Another key application is in drug delivery systems, where the linker attaches targeting ligands (e.g., peptides) to nanoparticles or liposomes. The aldehyde group also facilitates immobilization of proteins onto solid supports for biosensors or chromatography resins. Research labs use it for site-specific protein modifications to study structure-function relationships.
Safety and Storage
MAL-PEG-PH-CHO is an irritant and should be handled with gloves, goggles, and lab coats to avoid skin/eye contact or inhalation. Work in a fume hood when handling powders. The maleimide group is sensitive to thiols, so avoid contamination with reducing agents like DTT or β-mercaptoethanol. Store the compound at -20°C in a tightly sealed container with desiccants to prevent moisture absorption. Under proper conditions, it remains stable for up to 12 months. Solutions should be prepared fresh or stored at -80°C for short-term use. Disposal must comply with local regulations for reactive organic compounds.
B2B Procurement Guide
When procuring MAL-PEG-PH-CHO, specify the PEG chain length (e.g., PEG2000, PEG3400) and purity (≥95% for most applications). Bulk orders (100g+) may require customization and longer lead times. Reputable suppliers provide certificates of analysis (CoA) with HPLC/MS data to verify purity and molecular weight. For ADC development, opt for endotoxin-free grades. Compare prices across vendors, as costs vary by scale and PEG length. Consider logistics—cold chain shipping is often necessary. Some suppliers offer technical support for conjugation optimization, which can be valuable for first-time users.