Chloe Zhang
Dextran methacrylate (Dex-MA) is a biodegradable polysaccharide derivative that can be cross-linked by ionizing radiation. This makes it a potential replacement for synthetic hydrophilic polymers in current radiation technologies used for synthesizing hydrophilic cross-linked polymer structures. Dextran methacrylate can be coupled with 2-hydroxyethyl methacrylate (HEMA) and irradiated with visible light in the presence of camphorquinone (CQ) as a photoinitiator, and a coinitiator in a suitable solvent. This process results in the formation of hydrogels with potential applications in drug delivery systems for dental use.
| Characteristics | Values |
|---|---|
| Synthesis | Dextran is modified with hydroxyethyl methacrylate |
| Starting material | Crosslinkable dextran |
| Purpose | Development of new hydrogels as a drug delivery system in dental applications |
| Reaction | Dextran methacrylate (Dex-MA) is cross-linked by ionizing radiation |
| Application | Dextran methacrylate is a potential replacement for synthetic hydrophilic polymers in radiation technologies used for synthesizing hydrophilic cross-linked polymer structures |
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What You'll Learn
- Dextran methacrylate (Dex-MA) can be cross-linked by ionizing radiation
- Dextran methacrylate can be used to form biocompatible, insoluble hydrogels
- Methyl methacrylate (MMA) is graft-polymerized onto dextran in the presence of Ce4+ salts
- Dextran methacrylate is a biodegradable polysaccharide derivative
- Hydroxyethyl methacrylate (HEMA) can be coupled to dextran to create Dex-HEMA
Dextran methacrylate (Dex-MA) can be cross-linked by ionizing radiation
Dextran methacrylate (Dex-MA) is a biodegradable polysaccharide derivative that can be cross-linked by ionizing radiation. Dex-MA is formed by coupling 2-hydroxyethyl methacrylate (HEMA) to dextran. This process is monitored by FTIR and 1H-NMR spectroscopy. Dex-MA is considered a potential replacement for synthetic hydrophilic polymers in current radiation technologies used for synthesizing hydrophilic cross-linked polymer structures. The polymer structures formed are known as hydrogels and are used mainly for medical applications.
The Dex-MA hydrogels are formed in water through the reaction of Dex-MA with hydroxyl radicals and hydrated electrons. The rate of this reaction depends on the molecular weight and molar degree of substitution (DS) of Dex-MA. The DS of Dex-MA can be up to 0.66, and the molecular weight can range from 6 to 500 kDa. The reaction is also influenced by the presence of methacrylate groups on dextran molecules, which allow for fast and efficient hydroxyl radical addition reactions upon irradiation.
The radiation-induced cross-linking of Dex-MA has been demonstrated to be successful by Reichelt and coworkers. This process is versatile, additive-free, and clean, producing chemically cross-linked, biocompatible hydrogels. The formation of these hydrogels occurs at low doses of ionizing radiation due to the presence of a polymerizable methacrylic group (-MA) in Dex-MA.
The kinetic data obtained from studies on Dex-MA and its reaction with hydroxyl radicals provide valuable insights into the controlled synthesis of polysaccharide-based hydrogels and nanogels with predefined structures and properties. These controlled synthesis techniques can be further applied to develop new hydrogels for drug delivery systems in dental applications.
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Dextran methacrylate can be used to form biocompatible, insoluble hydrogels
Dextran methacrylate (Dex-MA) is a biodegradable polysaccharide derivative that can be used to form biocompatible, insoluble hydrogels. Dextran is a non-toxic, hydrophilic, bacterially-derived polysaccharide composed of linear α–1,6 linked D-glucopyranose residuals with a low percentage of α–1,2, α–1,3, or α–1,4 linked side chains. The presence of a polymerizable methacrylic group (-MA) in Dex-MA allows it to form hydrogels through crosslinking.
Crosslinking of Dex-MA can be initiated by ionizing radiation, resulting in the formation of biocompatible hydrogels with potential applications in regenerative medicine. The rate of crosslinking depends on the molecular weight and degree of substitution (DS) of Dex-MA, with higher DS values leading to increased crosslinking density. The equilibrium degree of swelling in the fabricated gels can be controlled by adjusting the initial concentration of the Dex-MA solution subjected to irradiation.
One method to synthesize Dex-MA hydrogels involves irradiating an aqueous solution of Dex-MA, which results in efficient hydrogel formation at low irradiation doses. This process is suitable for synthesizing hydrogel-based biomaterials and medical products, such as hydrogel wound dressings. Additionally, the hydrogels formed using this method have been found to be non-cytotoxic, as demonstrated by XTT assay evaluations.
Another approach to crosslinking Dex-MA involves chemically modifying the substrate polymer by incorporating cross-linkable groups prior to hydrogel synthesis. For example, dextran methacrylate esters have been used to design macroporous, interconnected scaffolds for tissue engineering. Radical crosslinking of methacrylated dextran derivatives using specific initiating systems has resulted in the formation of biodegradable hydrogels that are stable in physiological environments.
Furthermore, methacrylic anhydride modification is a common method for imparting photocrosslinking properties to polymers. Graft-substituted polymers with methacrylate groups can be photocrosslinked under UV irradiation, leading to the formation of methacrylate-modified hydrogels with potential applications in tissue engineering. The versatility of radiation technology allows for the production of chemically cross-linked, biocompatible hydrogels based on methacrylated polysaccharides without the need for additional additives.
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Methyl methacrylate (MMA) is graft-polymerized onto dextran in the presence of Ce4+ salts
Methyl methacrylate (MMA) can be graft-polymerized onto dextran in the presence of Ce4+ salts. Dextran is a water-soluble, biodegradable, and versatile polysaccharide used in wastewater treatment, pharmaceuticals, photography, cosmetics, and agriculture. It is often used as a starting material for the development of hydrogels as a drug delivery system in dental applications.
Methyl methacrylate (MMA), on the other hand, is a type of methacrylate, which is a versatile reagent with unique reactivity. This reactivity is due to the fact that Ce4+ is a strong one-electron oxidant, enabling it to generate radicals and radical cations, and promoting radical reactions.
The graft-polymerization process involves the copolymerization of dextran and MMA in an acidified aqueous medium. The reaction variables, such as monomer concentration, initiator concentration, backbone polymer content, pH, polymerization time, and temperature, significantly affect the grafting efficiency.
The resulting polymer from this process is neither soluble in water nor in acetone. A hot-pressed film of the copolymer exhibits better wettability, water absorption, and thromboresistance compared to poly-(methyl methacrylate) (PMMA). This process can be further optimized by controlling the molecular weight, molecular weight distribution, polymer structure, and the nature and percentage of ionic groups.
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Dextran methacrylate is a biodegradable polysaccharide derivative
Dextran methacrylate (Dex-MA) is a biodegradable polysaccharide derivative. Polysaccharides are known for their excellent biocompatibility, non-toxicity, and biodegradability. Dextran, a bacterially derived homopolysaccharide, is included in the WHO Model List of Essential Medicines and has a long-standing record of medical applications.
Dextran methacrylate is a dextran derivative with specific properties that can be further engineered to design and obtain a variety of microstructural forms such as fibres, scaffolds, or hydrogels. Due to the presence of a polymerizable methacrylic group (-MA), dextran methacrylate can form biocompatible, insoluble macroscopic hydrogels at low doses of ionizing radiation.
The formation of hydrogels from dextran methacrylate occurs through cross-linking by ionizing radiation. This process involves the reaction of dextran methacrylate with hydroxyl radicals and hydrated electrons in water. The rate constants of these reactions depend on the molecular weight and molar degree of substitution (DS) of dextran methacrylate.
The cross-linking of dextran methacrylate has potential applications in the field of tissue regeneration and medical applications. For example, hydrogels made from dextran methacrylate have been used as drug delivery systems for small molecules and in dental applications. Additionally, the inclusion of polyethylene glycol (PEG) in dextran-based hydrogels has been shown to improve the fragility and hardness of the gels, making them suitable for delivering high molecular weight peptides.
Overall, dextran methacrylate is a versatile biodegradable polysaccharide derivative that can be cross-linked to form hydrogels with a range of properties, making it a valuable material for various applications, especially in the medical field.
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2-Hydroxyethyl methacrylate (HEMA) can be coupled to dextran to create Dex-HEMA
The coinitiator plays a significant role in the crosslinking process, and its type, concentration, and water content in the solvent system can influence the swelling behavior and efficiency of the resulting hydrogels. Aliphatic or aromatic amines are commonly used as coinitiators, with concentrations ranging from 0.25 to 3.0 mol %.
The Dex-HEMA hydrogels have potential applications in drug delivery systems, particularly in dental applications. They have also been studied for their use in delivering small interfering RNA (siRNA) into targeted cells for cancer treatment. However, Dex-HEMA nanogels may have insufficient circulation times, which can impact their effectiveness in reaching and accumulating in tumor tissue.
To address this challenge, PEGylation of Dex-HEMA nanogels has been explored. PEGylation improves circulation time and reduces aggregation upon intravenous injection. This technique involves the modification of therapeutic molecules by conjugation with polyethylene glycol (PEG).
Additionally, Dex-HEMA has been investigated for its degradation kinetics in aqueous solutions. The stability of Dex-HEMA was found to be dependent on pH, with higher stability at alkaline pH compared to low pH.
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