Stability in normal saline solution increased upon coating the hydrogels with chitosan. Cryo-SEM Cryogenic scanning electron microscopy analysis of the coated hydrogels indicated a regular and compact surface with altered internal morphology.
Coated hydrogels exhibited antibacterial activity against Escherichia Coli. Release studies using rhodamine B as a low molecular weight hydrophilic drug showed that coating the hydrogels reduced the drug release kinetics, resulting in a sustained drug release [ 53 ].
Incorporating bioactive agents and nanoparticles onto alginate-based hydrogels have also been reported to enhance wound healing process. Yu et al. The wound dressings enhanced the formation of new blood vessel and enhanced re-epithelialization of the cutaneous wounds in vivo [ 54 ]. Incorporated simvastatin enhanced angiogenic differentiation of human umbilical vein endothelial cells in vitro.
Mohandas et al. The presence of zinc oxide reduced the swelling ratio of the wound dressing to 16— After two weeks, no significant change in the swelling ratio of the wound dressing was observed. The antibacterial activity of the wound dressing against S. The wound dressing was also effective against C. In vivo evaluation revealed re-epithelialization after 48 h revealing that the zinc oxide nanoparticles enhanced the proliferation and migration of keratinocyte cells to the wound site [ 55 ].
Singh et al. Different doses of gamma irradiation of 25 and 40 kGy were employed. The hydrogels containing 70 ppm nanosilver exhibited good antimicrobial activity [ 56 ]. The fluid absorption capacity of the hydrogels revealed their potential application for exuding wounds.
Nazeri et al. In vivo evaluation of the hydrogel on Wistar rat revealed that the time taken for wound healing was seven days when compared to alginate hydrogels without honey that required eight days for wound healing. The finding revealed that the presence of honey in the hydrogel stimulated angiogenesis and the growth of fibroblasts as a result of the delivery of hydrogen peroxide.
The hydrogel enhanced re-epithelialization in the wounds which was evident by the thickness of the epiderm. The wound healing of the hydrogels revealed the synergistic effect of the alginate hydrogel and honey [ 57 ]. Combining anticancer drug with alginate-based hydrogels and incorporation of antimicrobial agents onto alginate-based hydrogels resulted in enhanced re-epithelization in vivo.
Murakami et al. The hydrogel protected the wound by providing a moist environment for an enhanced healing process in full-thickness skin defects on rats. Granulation tissue and capillary formation in the healing-impaired wounds treated with the hydrogel and mitomycin C was significant on day seven. However, the degree of re-epithelialization was reduced, suggesting that the hydrogel hindered the migration of keratinocytes [ 58 ].
The hydrogels exhibited a minor healing effect on wounds that were not treated with mitomycin C. The wound dressing with the diameter of 10 mm absorbed 0. The wound dressing was easily applied and removed from the wound. The hydrogel absorbed substances involved in the wound healing process such as the growth factors and cytokines from the blood plasma or exudate in the wound, thereby stimulating wound healing process [ 58 ]. Kamoun et al. The maximum tensile strength and elongation of the hydrogel membranes decreased with an increase in the content of the sodium alginate.
The pore size and distribution also increased with increase in the content of the sodium alginate. The hydrogel membrane wound dressing system containing ampicillin exhibited sufficient antibacterial activity and were found to be suitable for wound dressing [ 59 ]. Preparation of hydrogels with good swelling capacity from the combination of alginate with other polysaccharides has been reported by some researchers.
Xing et al. The hydrogel was non-toxic to the cells [ 60 ]. Rudyardjo and Wijayanto prepared hydrogel chitosan-alginate using a plasticizer, lauric acid [ 61 ]. The addition of lauric acid enhanced the mechanical properties of the hydrogel. The mechanical properties revealed the suitability of the hydrogels for wound dressing.
Devi et al. The hydrogel exhibited fibrous morphology with pore sizes of — mm suggesting that the hydrogel has a potential to prevent bacterial infection, enhance wound healing, and favourable for cell attachment and skin formation [ 62 ]. Zhou et al. The ratio of the gelatin, sodium alginate, and hyaluronic acid in the hydrogels were , , 4.
The ratio of the polymers had no effect on the surface and cross-section morphologies of the hydrogels. Sodium alginate in the hydrogel matrix enhanced the water vapor transmission capacity of the hydrogel suggesting their potential application as wound dressing materials due to their ability to provide a moist environment for comfortable wound healing. However, the difference in the water vapor transmission rate of the hydrogels was not significant [ 63 ].
Factors that influenced the swelling capacity of alginate-based hydrogels are the composition of polymers used [ 52 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 ], the plasticizer [ 61 ], and the presence of nanoparticles [ 55 ].
Their good swelling capacity is a good feature for wound dressings because it reveals their potential to keep the wound environment moist, thereby reducing the risk of bacterial infection, thereby enhancing the wound healing process [ 25 ]. The antibacterial activity of the hydrogels was enhanced by the incorporation of antibacterial agents [ 54 , 59 ], combining the hydrogel with an anticancer agent [ 58 ], incorporation of nanoparticles [ 55 , 56 ], and the coating of the hydrogels with honey [ 57 ] and chitosan [ 53 ].
Sodium alginate-based films have been designed and reported by some researchers as potential wound dressing materials Figure 4. Films are useful for wound dressing. They enhance wound healing process, permeability to water vapor, carbon dioxide and oxygen, protect the wound from bacterial infections, and their mechanical properties can be improved by combining alginate with other polymers. However, they are not effective wound dressing for wounds with excessive exudates [ 10 , 11 ].
Sodium alginate films incorporated with essential oils were developed by Liakos et al. Essential oils, such as chamomile blue, cinnamon, lavender, tea tree, peppermint, eucalyptus, lemon grass, and lemon oils were incorporated onto the films and glycerol was used as a plasticizer [ 64 ]. Igepal surfactant was used in order to enhance the dispersion of the oil in the film matrix.
The addition of the surfactant enhanced the miscibility between the essential oil and the matrix. The films exhibited good antimicrobial activity. The films containing tea tree, cinnamon, lemon grass, and peppermint were able to inhibit C. The film containing elicriso oil was effective against C. The antibacterial activity of the films was selective and influenced by the nature of essential oil loaded onto the films.
Pereira et al. Their mechanical properties were suitable for skin applications and their swelling increased with increase in the amount of Aloe vera in the films [ 65 ]. The films were characterized by a smooth surface, high malleability, and thicknesses in a range The non-crosslinked films exhibited tensile strength and elongation values at break point, in a range of Addition of glycerol resulted in a significant decrease in the rigidity, which was evident by a decrease of the tensile strength in the range of The aforementioned behavior was attributed to the plasticizing effect of glycerol that decreased the polymer-polymer interactions and increased the mobility of the polymeric chains.
The addition of Aloe vera decreased the tensile strength and elongation at break of the films. In another research report, Pereira et al. The thermal and mechanical properties of the films were influenced by the loaded Aloe vera extract which revealed their potentials as wound dressing materials.
The film thickness was in the range of Blending alginate with Aloe vera caused a slight increase in the degradation temperature of the films, suggesting that a strong polymer-polymer interaction was visible from incorporating Aloe vera [ 66 ].
Alginate-based films incorporated with antibacterial and selected bioactive agents have also been reported by some researchers. George et al. The release profile of silver from the film was sustained over a period of seven days.
The percentage drug encapsulation in the films was in a range of Li et al. The water absorption rate of the strontium-loaded films decreased with an increase in the content of strontium. These findings revealed that the films become more hydrophobic after incorporating strontium.
The ultimate tensile stress, tensile strain and E-modulus of the films were in the range of 1. Rezvanian et al. From the pre-formulation studies, sodium alginate blended with pectin exhibited superior mechanical properties.
The rate of drug release from the film was influenced by the ratio of the polymers. The release of the drug from sodium alginate-pectin film loaded with simvastatin, sodium alginate loaded with simvastatin, sodium alginate-gelatin loaded with simvastatin was 0. In vitro cytotoxicity evaluation on normal human dermal fibroblast cells revealed cell viability of Thu et al. The bilayer was encapsulated with ibuprofen in the upper layer with a drug-free lower layer.
The bilayer films exhibited superior rheological and mechanical properties of The time required for diffusion of the water molecules across the bilayer films with the thickness of 3. The release of ibuprofen liberated from bilayer film was 0. The lower layer of bilayer film retained moist in the wound thereby accelerate epithelialization.
In vivo studies of wounds treated with bilayer films were covered with epidermis and newly formed dermis. Wounds treated with single layer films showed re-epithelialized epidermis composed of fewer keratinocytes on the surface [ 70 ]. Alginate-based films have also been used in combination with laser therapy and metal-based nanoparticles, resulting in enhanced wound healing in vivo.
Dantas et al. In vivo studies on male rats using a combination of laser therapy with the films enhanced rapid replacement of type III for type I collagen, blood vessels formation, epithelization, collagenization, and promoted good arrangement of the newly formed collagen fibres.
The combination improved the burn healing significantly resulting from the anti-inflammatory activities of chitosan and alginate that potentiate low-level laser therapy biostimulatory activity [ 71 ]. Sharma et al. The thickness of the ratio film was 5. The films were also effective at inhibiting Gram-positive bacteria which further revealed their potential in wound dressing [ 72 ].
Nanofibres prepared from sodium alginate have been reported by few researchers. They are potential materials for wound dressing. Nanofibres mimic the extracellular matrix, thereby enhancing the proliferation of epithelial cells and the formation of new tissue. However, the method of preparation influences the outcome of the nanofibers.
Controlling pore structure of the nanofibers is difficult when using electrospinning technique. Using self-assembly method of preparation results in nanofibers with shapes that are not uniform.
Drug loading onto the nanofibers is low when fiber mesh or self-assembly is used for drug loading process [ 75 , 76 ]. The addition of nanoparticles onto nanofibres promotes their antibacterial activity. Shalumon et al. The nanoparticles size was nm and different concentrations, namely: 0.
Nanofibers containing 0. The nanofibers were effective against S. In the preparation of the nanofibers, the ratio of alginate used can result in structural defects. Hu et al. The spinnability of the alginate solution into nanofibers was possible by the addition of polyethylene oxide. The ratio of sodium alginate and polyethylene oxide used to prepare the nanofibers were , , , and The smoothness and the diameter of the nanofibers were influenced by the ratio of sodium alginate and polyethylene oxide used for the preparation.
Increasing the ratio of alginate in the nanofibres resulted in spindle-like defects and decreased diameter. The tensile strength of the nanocoated hybrid yarn was superior to the uncoated yarn [ 78 ]. The antibacterial and wound healing effects of essential have been employed in alginate-based nanofibers.
Hajiali et al. The electrospinnability of the solution of alginate was made possible by the use of polyethylene oxide and Pluronic F The elongation at break was 2.
Their good mechanical properties indicate that the nanofibers are flexible, can be easily handled without breaking, and can adapt to skin wounds. Sodium alginate-polyethylene oxide-lavender oil was effective against S.
In vivo studies of the nanofibers on burns revealed a complete disappearance of erythema within 48 h, which indicate that the nanofibers ability to prevent inflammation induced by UVB irradiation.
The nanofibers were important in suppressing the production of cytokines and their anti-inflammatory activity was enhanced by the addition of lavender essential oil in the nanofibres. Alginate-based nanofibers have been prepared using synthetic polymers, such as poly vinyl alcohol and poly ethylene oxide.
The nanofibers were prepared from sodium alginate and poly vinyl alcohol. The nanofibers were characterized by a uniform and continuous fiber formations with fiber diameter of The nanofibers air permeability effect of 0. The nanofiber revealed enhanced wound healing characterized by re-epithelization, vascularization and formation of hair follicles.
The nanofibrous mat exhibited healing performance when compared to other wound dressings. The nanofiber acted as an artificial skin on the wound region till the formation of a new tissue [ 81 ].
Park et al. In the blend, the conductivities were reduced when increased amount of poly ethylene oxide was added because of the low viscosity of poly ethylene oxide compared to sodium alginate. Immersion of the nanofiber in deionized water and phosphate buffer solution indicated the ability of the nanofibers to absorb exudates [ 82 ]. Antibacterial agent has been incorporated onto alginate-based nanofibres.
Fu et al. The water vapor permeability of the nanofibers was Increasing the amount of moxifloxacin hydrochloride did not increase the diameters of the nanofibres. The antibacterial activity of the nanofibers increased with increase in the concentration of moxifloxacin hydrochloride in the nanofiber. In vivo studies of the nanofibers in rats with full-thickness round wounds with a surface area of 0. The nanofibers also exhibited good antibacterial activity against S.
Foams are solid porous matrices that can be sterilized and administered to wounds without causing discomfort to the patient. However, if parameters such as thickness, density, and mechanical properties, such as tensile strength and elongation of the freeze-dried foam, are not properly tailored, their application in wound dressing can cause discomfort to the patients and maceration of skin around the wound periphery [ 84 ].
Foams can absorb exudate, protect the wound from maceration, enhance gaseous exchange, and can provide a moist environment for the wound. Wounds that foam dressings are applicable are traumatic wounds, burns, diabetic ulcers, etc.
Foam dressings can also be used as a secondary dressing [ 85 ]. Alginate-based foams are characterized by extended hydration time, they can be removed from wound site without severe damage to the tissue. However, their use requires frequent dressing and they are not suitable for wounds with low exudates, and dry wounds [ 10 ].
Alginate-based foams that have been reported were prepared by loading antibacterial agent. Hegge et al. The foam loaded with curcumin exhibited extended hydration time. However, E. The foams hydrated rapidly when in contact with the physiological solution and remained intact after the release of the loaded curcumin, suggesting that they can be removed from the wound site without tissue damage prior to irradiation, thereby minimizing light attenuation in a photodynamic therapy PDT [ 86 ].
The foams were loaded with 5,10,15,tetrakis 4-hydroxyphenyl porphyrin. The foams were thin and flexible and easy to handle. The percentage of drug loaded onto the foam was between 0. Topical formulations are semi-solid dosage and occur in the form of gels, ointment and creams [ 88 ]. It offers several advantages such as patient compliance, incorporated drugs are delivered more selectively to a target site and it overcomes fluctuation in the levels of drug [ 88 ].
Skin is the ideal site for the delivery of drug substances for systemic and local effects. The epidermal and dermal of the skin act as a barrier that inhibits drug transport. Selecting the right excipient can result in reduced surface adsorption, immunogenic effect, and overcome degradation [ 89 ].
Preparing the formulation is very important because it affects the drug delivery, integrity of the dosage, and duration of the efficacy of the active agent [ 89 ].
Loading the right bioactive agent is very important because its interaction with the excipient influences its permeation effect, its stability, its rate of metabolism, and the rate of drug delivery [ 89 ]. There is very little research report on sodium alginate-based topical formulation for wound dressing. However, the application of topical formulation for wounds is limited by reduced penetration in open wounds, risk of hypersensitivity reactions, systematic absorption in large wounds, contamination of the formulation from day-to-day bodily contact because of frequent applications and alteration of normal cutaneous flora [ 89 ].
Sodium alginate has been employed in topical formulation for wound healing. Ahmed et al. The drug content of the gels was in the range of The gels exhibited good viscosity in the range of Lyophilized wafers are prepared by freeze-drying polymer solutions resulting in solid porous structures that can be applied to exuding wound surfaces [ 91 ].
Their physical structure is similar to foam wound dressings. They also act as drug delivery systems and can be loaded with bioactive agents that can enhance wound healing process. They absorb wound exudates and transform into a gel and provide a moist environment useful for wound healing. Their preparation process is very important because poor preparation process from poor ratios of materials can result in rigid, sticky, and non-porous wafers that are not suitable for wound dressing [ 92 ].
Wafers loaded with silver sulfadiazine have been reported. Boateng et al. It contained 0. Formulation with the absence of sodium alginate was characterized by a non-porous morphology. The addition of sodium alginate in the formulation resulted in uniform pores in the polymeric network. The water uptake of the wafers was also influenced by the presence of sodium alginate. The wafers containing only sodium alginate exhibited a high water uptake of Increasing the content of gelatin in the hydrogels decreased the swelling capacity of the hydrogels.
Formulations containing a higher amount of sodium alginate released the loaded drug faster when compared to other formulations over a period of 7 h. The high swelling ability, mechanical properties, and drug release profiles suggest that sodium alginate-based wafers are potential wound dressings for highly exuding wounds [ 93 ].
In severe cases, gangrene can set in if ulcers go untreated. Wounds like pressure ulcers, diabetic ulcers, and venous ulcers can be treated safely and effectively with an alginate dressing. Alginate dressings are absorbent wound care products that contain sodium and calcium fibers derived from seaweed.
They come in the form of flat dressings that can be placed over open ulcers and rope dressings that are used for packing the wound, which absorb fluids and promote healing with pressure ulcers, diabetic foot ulcers, or venous ulcers. An individual dressing is able to absorb up to 20 times its own weight. These dressings, which are easy to use, mold themselves to the shape of the wound, which helps ensure that they absorb wound drainage properly. This also makes these dressings ideal for using on ulcers in areas that are difficult to dress, such as heels and sacral areas.
Alginate dressings are dry when initially placed on an open wound and become larger and more gel-like as they draw in fluids.
This helps clear out the wound, prevents it from becoming dry, and protects it from harmful bacteria, which helps lower the risk of infection. These dressings also help promote new skin growth during the wound healing process by ensuring that the wound area stays moist.
This encourages natural debridement via enzymes, which supplements the wound care provided by wound care practitioners in a clinical setting. The debridement process removes dead or damaged skin, promoting a healthier wound environment that aids wound healing.
Alginate dressings can also help wounds that are bleeding. The calcium in these dressings helps stabilize blood flow, which slows bleeding.
Treating wounds with alginate dressings is a straightforward process if you follow the correct wound care procedure using these steps:. Keep in mind that alginate dressings are designed for use on draining wounds or wounds with excessive amounts of fluid. They should not be used on wounds that have very little drainage or they may dry them out, which slows the healing process. Although alginate dressings typically keep wounds moist for faster healing, they need to form a gel in order to do so.
In some cases, this gel does not form, which increases the risk of having the dressing stick to the skin and cause irritation or damage. How much the alginate dressing swells depends on the chemical composition of the product and the botanical source.
Alginates can be used in a variety of wound situations. With sloughy wounds that also produce exudate, the alginate dressing provides a moist cover to prevent the wound from drying out and allowing the wound to heal more quickly. Common wound situations where alginate dressing can be applied are:. Most of the time, alginate dressings can be left unchanged for days unless exudate capacity is reached. With infected wounds, the wound bed should be inspected daily. In general, using an alginate dressing is a straightforward process that follows the best practices of wound care:.
Along with being an excellent absorbent, alginate dressings protect the affected area from bacterial infections and maintain a moist environment that promotes quicker and more efficient healing. Alginate dressing is easy to apply and has high manipulability. Furthermore, few individuals are allergic to alginates.
Alginate dressing is not an appropriate treatment for a wound that is bleeding heavily, or for wounds that are dry or have minimal exudate. They are also not a good choice for surgical implantations or third-degree burns. Other counter-indications are an allergy to any of the components in the dressing.
Caution should also be used in using the dressing on tumors or any wound with exposed blood vessels because removing the dressing may cause fresh bleeding.
While not as well-known as some other dressing types, alginate dressing has properties which make it a good choice for a variety of wound types, especially wounds requiring absorbent dressing. The views and opinions expressed in this blog are solely those of the author, and do not represent the views of IncontinenceSource, Kestrel Health Information, Inc. Being a wound care professional is often a lot like being a detective.
You have to decide what caused the wound, what is contributing to its not healing and how you are going to get it to heal. It was an established wound care patient calling me to state that his negative pressure therapy device went awry. He was requesting advice to View the discussion thread.
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