2-methacryloyloxyethyl phosphorylcholine, commonly known as MPC, is a monomer used in the creation of advanced biomaterials. It is a synthetic molecule designed to mimic a component of human cell membranes. This molecular mimicry is the foundation of its utility in medical and biomedical engineering fields. MPC’s structure allows it to be built into larger structures, forming materials with unique properties for sensitive applications.
Core Chemical Properties
A defining feature of MPC is its zwitterionic nature, meaning the molecule contains both a positively and a negatively charged group. These opposite charges cancel each other out, resulting in an electrically neutral molecule. This charge balance is a primary reason MPC surfaces interact so minimally with their biological surroundings.
This zwitterionic property contributes to MPC’s hydrophilicity, or its strong attraction to water molecules. In an aqueous environment like that inside the human body, the MPC molecule attracts and organizes water, forming a tightly bound hydration layer. This layer of water acts as a physical barrier, masking the underlying material.
The combination of a neutral charge and a hydration shell gives rise to MPC’s bio-inertness. Surfaces modified with MPC resist the attachment, or adsorption, of biological entities such as proteins and cells. The initial adsorption of proteins onto a foreign surface is what triggers negative responses, like blood clotting or inflammation. By preventing this first step, MPC-based materials can avoid detection and remain stable within the body.
Polymerization and Material Formation
While a single MPC molecule has beneficial properties, its utility is realized when many are linked together to form a material. MPC is a monomer, a single chemical building block. Through polymerization, these monomers are bonded into long, repeating chains, creating a substance known as poly(MPC) or PMPC. This process transforms the monomer into a stable, solid material.
Radical polymerization is a common method used to create PMPC, allowing for the synthesis of polymers with tailored structures. The resulting PMPC can then be applied in several physical forms. For instance, it can be used to create ultra-thin surface coatings on existing medical devices.
PMPC can also be formulated to form hydrogels, which are networks of polymer chains that absorb large amounts of water, creating soft, flexible materials. In other applications, PMPC is blended with plastics as an additive. This versatility allows engineers to integrate the benefits of MPC into a wide array of products.
Biomedical and Industrial Applications
In ophthalmology, PMPC is a component of high-performance soft contact lenses. Its ability to attract and hold water enhances moisture retention on the lens surface, leading to improved comfort for the wearer and resisting the buildup of protein and lipid deposits from tears that can cloud the lens.
Within the cardiovascular field, PMPC coatings are applied to devices that come into contact with blood, such as arterial stents, catheters, and the internal tubing of heart-lung machines. These surfaces are exceptionally resistant to thrombosis, or the formation of blood clots. The PMPC surface minimizes the activation of platelets and other clotting factors, improving the safety of these life-saving devices.
In orthopedics, PMPC is explored for its potential as a lubricating agent on the surfaces of artificial joints. The tightly bound water layer on a PMPC surface creates an extremely lubricious interface that can mimic the function of natural cartilage. This application aims to reduce friction and wear in prosthetic hips and knees, extending the operational lifespan of the implants.
Beyond these areas, PMPC is used to create specialized nanoparticles for targeted drug delivery systems and as non-adhesive coatings on laboratory equipment. For drug delivery, the PMPC shell can encapsulate therapeutic agents, improving their stability and solubility in the bloodstream. In cell culture, coating petri dishes with PMPC prevents cells from sticking to the bottom, encouraging them to aggregate and form more biologically relevant three-dimensional structures for research.
Biocompatibility and Safety Profile
The safety of MPC-based materials stems from biomimicry. The phosphorylcholine chemical group is naturally present on the outer surface of human cell membranes, including those of red blood cells and endothelial cells lining blood vessels.
Because the body’s immune system encounters this structure on its own cells, it recognizes it as “self.” When a medical device coated with PMPC is introduced, its surface presents this familiar chemical signature. This molecular camouflage prevents the activation of the body’s defense mechanisms, like the inflammatory response.
The result is a material with low toxicity and a strong safety record in clinical use. This high degree of biocompatibility has established PMPC as a benchmark material for medical devices intended for both short-term and long-term implantation.