Poly-L-histidine
Options: HBr or HCL
CAS No: 26062-48-6
Molecular weight: 3-70K Da
Purity: 99.9%
Appearance: white solid
Minimal order quantity: 10 gram
Poly-L-histidine is a synthetic polypeptide composed of repeating L-histidine amino acid residues, offering unique pH-responsive properties that make it invaluable in pharmaceutical and biotechnology research. This biocompatible polymer exhibits remarkable sensitivity to pH changes, undergoing conformational transitions in physiological pH ranges due to the imidazole groups present in its histidine residues. This distinctive characteristic enables poly-L-histidine to serve as an intelligent material for controlled drug delivery systems, gene therapy vectors, and various biomedical applications.
The pH-dependent behavior of poly-L-histidine stems from its protonation state at different pH levels. At acidic pH, the polymer becomes positively charged and more hydrophilic, while at neutral to basic pH, it transitions to a less charged, more hydrophobic state. This property makes it particularly useful for designing drug carriers that can release their payload in response to the acidic microenvironments found in endosomes, tumor tissues, or inflamed areas. Researchers leverage this functionality to develop targeted delivery systems that minimize side effects while maximizing therapeutic efficacy.
In addition to drug delivery applications, poly-L-histidine serves as an excellent tool for membrane studies, protein purification, and as a model polymer for investigating peptide-membrane interactions. Its biocompatibility and biodegradability make it a safer alternative to many synthetic polymers, reducing concerns about long-term accumulation in biological systems. The polymer can be synthesized in various molecular weights to suit specific application requirements.
FAQ
Most frequent questions and answers
Poly-L-histidine is primarily used in drug delivery systems, gene therapy vectors, and targeted therapeutic applications. Its pH-responsive nature makes it ideal for designing carriers that release drugs in acidic environments like endosomes or tumor tissues. It’s also employed in membrane interaction studies, protein purification, biosensor development, and as a coating material for nanoparticles.
At acidic pH (below 6.0), the imidazole groups in poly-L-histidine become protonated, making the polymer positively charged and hydrophilic. At neutral to basic pH (above 7.0), the polymer becomes less charged and more hydrophobic. This transition allows controlled release of encapsulated drugs or facilitates membrane disruption for intracellular delivery.
Poly-L-histidine is typically available in various molecular weight ranges, from low (1-5 kDa) to high (50-100 kDa or more). The choice of molecular weight depends on your specific application—lower molecular weights are often used for coating applications, while higher molecular weights may be preferred for structural or drug delivery purposes.
Store poly-L-histidine as a lyophilized powder in a dry, cool place, preferably at -20°C or below. Keep the container tightly sealed and protected from moisture. When stored properly, the material typically remains stable for extended periods.
Yes, poly-L-histidine is generally biocompatible and biodegradable. As a polypeptide composed of natural amino acids, it can be broken down by proteolytic enzymes in biological systems. However, the degree of biodegradation depends on factors like molecular weight, concentration, and the specific biological environment.
Poly-L-histidine can be dissolved in water or aqueous buffers, with solubility being pH-dependent. It dissolves more readily at acidic pH when the polymer is protonated. For neutral pH applications, you may need to first dissolve it at acidic pH and then adjust the pH gradually. Some formulations may also dissolve in DMSO or DMF.
Yes, poly-L-histidine can be chemically modified through various conjugation strategies. The amino groups at the N-terminus and the imidazole rings can serve as reactive sites for attaching drugs, targeting ligands, imaging agents, or other functional groups to enhance its properties for specific applications.
The difference lies in the stereochemistry of the histidine residues. Poly-L-histidine contains the naturally occurring L-form of histidine, while poly-D-histidine contains the D-enantiomer. L-form polymers are generally more susceptible to enzymatic degradation, while D-form polymers may offer enhanced stability in biological environments.