Surface Modification and Functionalization

Surface modification and functionalization are critical processes in various industries, including pharmaceuticals, materials science, and biotechnology. These processes involve changing the surface properties of a material to enhance its performance, functionality, and compatibility with other materials or biological systems. BOC Sciences is a leading provider of PEG-based surface modification and functionalization services, offering a wide range of solutions to meet the diverse needs of its customers. We can select appropriate polyethylene glycol (PEG) or PEGylated substances for the materials provided according to customer needs, and carry out high-quality PEG modification and functionalization services.

What is Surface Modification?

Surface modification involves changing the physical or chemical properties of a material's surface to improve its performance or functionality. This includes changing the material's surface roughness, wettability, adhesion, or biocompatibility. Surface modification can be achieved through various techniques such as chemical treatments, plasma treatments or coating processes. Functionalization, on the other hand, involves attaching functional groups or molecules to the surface of a material to impart specific properties or functions, including the introduction of reactive groups for further chemical modification, the addition of bioactive molecules for biomedical applications, or the incorporation of conductive materials for electronic devices. Functionalization can be achieved through a variety of methods, such as chemical reactions, physical adsorption, or covalent bonding.

Fig. 1. Surface modification of polysaccharide nanoparticles by polyethylene glycol (Mol. Pharmaceutics. 2017, 14(12): 4403-4416).

Biomedical materials are mainly in contact with blood, tissue engineering, medical equipment or organs, and some biological reactions always occur between the interfaces, such as the adsorption of plasma proteins, the formation of thrombus, etc. Therefore, biomedical materials used to manufacture artificial hearts and artificial blood vessels must have excellent blood compatibility. As we all know, PEG is an excellent hydrophilic polymer with good blood compatibility. Its coating process for modifying and functionalizing biomedical materials has been widely accepted by the medical industry.

Why is PEG Used?

PEG is a kind of linear or branched polyether derived from ring-opening polymerization of epoxyethane. In spite of being a high molecular polymer, PEG possesses some excellent properties such as strong polarity and the resulting hydrophilicity and water-solubility. Due to its excellent hydrophilicity, PEG can make the material have a lower friction coefficient in the wet state, while in the dry state there is no different from ordinary materials, which can improve the mobility of the material and reduce the probability of adhesion to the tissue. On the other hand, the polymer chain of hydrated-PEG can affect the microscopic dynamic environment of the interface between blood and material, and reduce the interaction between plasma protein and material, thus PEG has good blood compatibility and can be used to modify various biomedical materials. In addition, because PEG can be soluble in many different organic solvents, such as dimethylformamide (DMF), tetrahydrofuran (THF), etc., it is easy to process PEG coating on the surface of medical devices by dipping or spraying.

PEG Surface Modification and Functionalization

At BOC Sciences, we offer comprehensive PEG-based surface modification and functionalization services to help our customers optimize the performance of their materials and products. Our experienced team of scientists and engineers work closely with customers to understand your specific requirements and develop custom solutions to meet your needs. Whether you are looking to improve the biocompatibility of medical devices, enhance the adhesion properties of coatings, or functionalize nanoparticles for drug delivery applications, we have the expertise and capabilities to deliver high-quality results.

Physical Adsorption of PEG

Physical adsorption is the most traditional strategy, taking advantages of simple operation, relatively few control conditions and low experiment threshold. Physical adsorption is the force between the adsorbed fluid molecules and the solid surface molecules, which is also called Van der Waals force. This is a reversible process. When the gravitational force between the molecules on the solid surface and the gas or liquid molecules is greater than that inside the gas or liquid, the molecules of the gas or liquid will be adsorbed on the solid surface. Although this method is simple, it still faces the problems of low adsorption strength and unstable of formed layer. Consequently, this strategy of surface modification is suitable for the cases that do not require bigger amount and higher adsorption strength PEG on the surface, or that the substrates have strong adsorption capacity.

Surface Grafting of PEG

Surface grafting strategy is available for surface modification only when both the substrate surface and PEG terminal have reaction activity. For silicon and other silicon-based substrates, PEG-silane coupling reaction is an ideal method. Grafted polymers chains can be securely bonded on the substrates by the high strength Si-O bonds even in tough environment. Moreover, click chemistry is also suitable for the surface modification process due to its characteristics and advantages of mild and controllable reaction conditions, as well as its high yield. Through surface grafting strategy, the grafted bonds are stable enough so that the modified materials will become more durable, and the types of grafted PEGs can be easily chosen or synthesized in advance.

Surface Polymerization of PEG

Surface polymerization is a strategy that the macromolecules grow on the substrate surfaces by polymerization using the appropriated monomers and reagents. In this method, surface-initiated free radical polymerization is usually adopted, and commonly used methods for generation of free radicals involve ozone pretreatment, plasma treatment, ultraviolet irradiation and etc. Surface polymerization is an efficient PEG surface modification strategy with high surface grafting density. In addition, it is more versatile which allows various of substrates with different properties and structures to be constructed.

Functionalization of Nanoparticles

PEG is one of the most commonly used polymers for functionalizing nanoparticles due to its biocompatibility, water solubility, low toxicity, and ability to form a hydration layer on the nanoparticle surface. Functionalizing nanoparticles with PEG has the following benefits: a) PEG can provide a steric barrier to prevent nanoparticle aggregation and enhance their stability in biological fluids; b) PEG can improve the solubility of nanoparticles in water and biological fluids, making it more suitable for in vivo applications; c) PEG can enhance the biocompatibility of nanoparticles by reducing their immunogenicity and toxicity. We can modify the surface of nanoparticles with various functionalized PEGs such as carboxyl, amino, thiol, and hydroxyl groups. This enables the conjugation of targeting ligands, drugs, imaging agents, and other molecules to the nanoparticle surface.

Biomolecule Immobilization

PEG can also be used to immobilize bioactive molecules such as proteins, antibodies or enzymes to material surfaces, which can be used to create biosensors, diagnostic devices or drug delivery systems with enhanced specificity and functionality. For example, in biosensors, PEG can be used to attach antibodies or enzymes to material surfaces, allowing the detection of specific biomolecules with high sensitivity and accuracy. In diagnostic devices, PEG can be used to immobilize proteins that can detect disease or infection, providing fast and reliable results. BOC Sciences not only supports the immobilization of biomolecules, but also supports PEGylation services for biomolecules, including nucleic acids, antibodies, cytokines, peptides and proteins, etc.

PEGylation Analysis and Characterization

In addition to surface modification and functionalization services, BOC Sciences offers comprehensive characterization and testing services to ensure the quality and performance of customers' materials and products. Our state-of-the-art facilities and equipment allow us to perform a variety of analytical techniques such as surface analysis, spectroscopy, microscopy and mechanical testing to evaluate the performance of modified surfaces and coatings.

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References

1. Xiao, X.F. et al. Surface modification of poly ethylene glycol to resist nonspecific adsorption of proteins. Chinese Journal of Analytical Chemistry. 2013, 3(41): 445-453.
2. Bamberger, D. et al. Surface modification of polysaccharide-based nanoparticles with peg and dextran and the effects on immune cell binding and stimulatory characteristics. Mol. Pharmaceutics. 2017, 14(12): 4403-4416.