Cellulose, considered the most widespread organic material and polysaccharide on Earth, occurs in nature primarily as microfibrils in the cell walls of wood and plants, algal cell wall, and the Ascidian sac of tunicates. Traditionally, cellulosic materials have been used in industry to make paper and textiles.
If you are looking for more details, kindly visit our website.
All the specific properties of cellulose make it an attractive substitute for plastics. As a replacement for traditionally used synthetic materials, it is expected to show similarly promising performance characteristics while maintaining an acceptable level of efficiency. Cellulose fibres of wood or plant origin have long shown potential as a reinforcement for composites (Ramamoorthy et al., ), in addition to the commonly used glass fibres (Thomason, ) and carbon fibres (Chawla, ). The challenge is to find a biobased option for the composite matrix that is responsible for fibre binding, as two chemically different components often have poor interfacial compatibility, which can lead to water absorption, reduced mechanical properties of the material (Nishino and Arimoto, ) and shorter product life. In the following sections, a brief overview of the most relevant applications of plant cellulosic fibres in the field of polymer bio-composites is presented, taking into account the technological possibilities and limitations of cellulose processing, and with a special focus on the applicability of this biomaterial in the packaging industry, currently considered as the largest consumer sector.
The plastics market is an important part of the global economy. For example in Poland, the demand for plastics is 3.5 million tonnes per year and the biggest consumer is the packaging sector. This sector consumes 30&#;40% of all plastics processed. The biggest role is played by polyolefins: LDPE and LLDPE, PP and HDPE, as well as PET. These polymers account for more than 80% of the plastics demand for packaging. On the other hand, 26% of the plastics produced are used in the construction industry and one tonne in ten is used for the automotive industry.
There are significant differences in the lifespan of different plastic products. Some are used for a very short period of time while others last for decades. However, the problem arises when we no longer need a given product or plastic packaging. When thinking about polymer technology, a great challenge is to minimize plastic waste (Datta and Kopczyńska, ; Liu et al., ) and to reduce environmental pollution (Platnieks et al., ).
Growing environmental awareness requires the development of materials that are less harmful to our surroundings and make use of the natural environment around us without harm. In order to achieve a compromise between sustainability principles and polymer technology, it is very important to use environmentally friendly materials (Barczewski et al., a; Bartos et al., ; Ates et al., b) and to reduce harmful chemicals used in polymer processing (Lisuzzo et al., ; Yang et al., ; Bertolino et al., ). Therefore, the search for natural substitutes is a current need.
Biodegradable and compostable packaging made of bioplastics is therefore today an example of an ecological alternative to plastic films and fits perfectly into the principles of the ClosedLoop Economy. Cellulose is a polymer that is cheap, hydrophilic, chiral and easy to modify chemically. It is biodegradable and socially acceptable. All these characteristics make cellulose an attractive substitute for plastics. However, despite these undoubted advantages and indisputable arguments, bioplastics are still at an early stage of development and occupy a small market niche. Their further development will be linked to improvements in properties, availability and price, as well as the introduction of organic waste collection systems for composting.
Technological possibilities and limitations are also not insignificant. To analyze this issue, it is worth looking at the properties of cellulose, which may determine the possibilities of its use in polymer processing. An important aspect in this regard is, first of all, the question of compatibility of cellulose fibers with the polymer matrix. The hydrophilic nature of cellulose contributes to the widespread use of water-soluble matrices in the production of composites. However, the use of nanofibers and cellulose nanocrystals in composites with hydrophobic matrices may encounter problems due to weak interfacial bonding.
Thus, the moisture content of cellulose fibers is an extremely important parameter, as it determines a number of its properties. The ability to absorb water influences the molecular packing, the stresses occurring inside the fibers, the mobility of the polymer chains or the availability of active centers important during modification, as well as the size of the pores. Cellulose in equilibrium with the atmosphere always contains absorbed moisture, generally between 4 and 5% by weight. (Mihranyan et al., ). Considering the applications in polymer composites where fibers act as a filler, this may be a certain disadvantage and limitation. This is because the water content may contribute to poor mechanical properties of the polymer composite (Espert et al., ), poor adhesion of the filler to the hydrophobic polymer matrix (Chen et al., ) and result in a decrease in the decomposition temperature, i.e., a deterioration in the thermal stability of the material (Sombatsompop and Chaochanchaikul, ). Moreover, according to the available information, it can be concluded that water content significantly contributes to cellulose degradation. The hydrolysis reaction of the glucosidic bonds contributes to the attachment of unstable acetal chain ends and to the reduction of the molecular weight. Moreover, considering that water is the main product of the thermal decomposition of cellulose, especially during the initial phase of thermal treatment, the considered process can be attributed to autocatalytic reactions (Scheirs et al., ; Poletto et al., ; Poletto et al., ). In this situation, the moisture content of the biopolymer is of great importance to obtain a material with the best possible properties (Manaf et al., ; Liu et al., ; Leszczyńska et al., ; Mao et al., ).
According to the literature, the changes that the water contained in cellulose undergoes during conventional heat treatment can be divided into the following three stages (Scheirs et al., ): physical water loss (<220°C), chemical water loss (220&#;550°C), and chemical water loss in pyrolysis (>600°C). From the point of view of materials science, the first and second stages of water loss are the most important. The first of these relates to the problem of drying cellulose prior to incorporation into a polymer matrix. Then, the subsequent chemical water loss process (220&#;550°C) can help to understand and analyze the thermal behavior of the produced polymer composites with respect to the initial moisture content of the cellulose fibers.
Our research in the field of hydrophobization of cellulose fibers, conducted for potential applications to polymer composites, includes the replacement of heat treatment with a new method (Cichosz and Masek, ). Although published studies concern cellulose fibers (Arbocel UFC100 - Ultra Fine Cellulose), but considering its chemical structure and that of bionanocellulose, it is the same. Thus, any modifications can be carried out very similarly, which may be important from the point of view of the directions of development of biopolymers and bioplastics, whose further development and new applications will be related, among others, to the improvement of properties.
In a published study, we proposed and described a novel hybrid chemical modification method using maleic anhydride and solvents of different polarity to minimize the moisture content and intensify the cohesion forces of the filler-matrix pair ( ). This is the reverse of the commonly used process of grafting the polymer matrix with maleic anhydride (MA) followed by blending with cellulose. In our work, we presented an alternative approach that aims to use MA not as a direct coupling agent (i.e., coupling agent) of the cellulose to the polymer matrix, but as an agent that changes the surface properties of the cellulose (e.g., hydrophobicity, specific surface area).
Thus, the described method consists of two steps: solvent exchange (water to ethanol or hexane) and chemical modification by maleic anhydride (MA) grafting. Previously, the concept of solvent exchange was proposed by Ishii and coworkers (Ishii et al., ). It was found then that the presence of solvent molecules between cellulose macromolecules relaxes the surface fractal of microfibril aggregates. As a consequence, the aggregate geometry changes to a bulk fractal (Laine et al., ). The overall conclusion of the study by Ishii et al. is that solvent exchange improves molecular mobility and shortens the characteristic length along cellulose microfibrils (Ishii et al., ). We therefore used the chemical filler modification process implemented in our study to alter the molecular mobility of the biopolymer during solvent exchange. As a result, the cellulose underwent changes in physical structure (swelling in solvent) and surface properties (by chemical grafting with maleic anhydride MA) after complex treatment.
By means of infrared spectroscopy (FT-IR), it has been demonstrated that the use of different solvents can contribute to the efficiency of the modification process, as they cause rearrangements in the hydrogen bond structure, as well as swelling of the biopolymer, consequently affecting its molecular packing. Based on the results obtained, it can be concluded that the use of ethanol greatly contributed to the reduction of water absorption capacity of cellulose (Cichosz and Masek, ).
Moreover, investigations carried out using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) revealed an improvement in the thermal resistance of the fibers as a result of the new hybrid chemical modification. A shift in the value of 5% temperature loss in weight from 240 to 306°C was observed as a result of the use of a solvent in the modification process.
We extended the study to analyze the effect of cellulose moisture content on the modification process by drying the test fibers, or not, prior to hybrid chemical modification. Based on the results obtained, we found that cellulose pre-dried before modification showed increased heat resistance, while non-dried fibers were more susceptible to maleic anhydride (MA) modification (Cichosz and Masek, ).
It should be emphasized that for all modifications carried out, a reduction in moisture content was observed, ranging from about 4% for thermal drying to 1.7% for hybrid MA modification. This result is extremely promising considering the possibility of using the treated fibers in a polymer matrix. It is also worth noting that MA treatment can contribute to the formation of nanofibrils (Iwamoto and Endo, ).
We found the presented experimental results to be a promising and effective way to improve the interactions of the cellulose filler with the potential polymer matrix. Therefore, the next research was concerned with the application of modified fibers in the polymer.
As a result, we obtained and described the properties of composites based on ethylenenorbornene copolymer (TOPAS Elastomer E-140) filled with cellulosic plant fibers (Cichosz et al., ). It is worth noting that similar systems, e.g., polyethylene (PE) or polypropylene (PP) modified with MA, similar to ethylene-norbornene copolymer filled with natural fibers, have been reported in the literature as polymer composites with good mechanical characteristics (Chen et al., ; Li et al., ; Yeh et al., ; Sato et al., ).
Therefore, we evaluated the change in the filler structure and stiffness of the polymer composite based on ethylene-norbornene copolymer obtained with its participation, as well as the tensile strength and elongation at break using static mechanical analysis methods. As a result, the conducted tests showed a significant improvement in the performance of the composite, tensile strength of 38.8 MPa and 510% elongation at break (Cichosz et al., ). The values obtained are higher than for the pure polymer matrix and, importantly, previously impossible to achieve as a result of regular modification with maleic anhydride (MA). Considering the available literature data, for example, in the case of a polyethylene-based composite filled with modified cellulose fibers, which is a system similar to ethylene-norbornene copolymer, the tensile strength usually varies between 25 and 40 MPa (Arrakhiz et al., ; Sato et al., ), depending on the source and type of polyethylene.
For more information, please visit henggu jianxin.
Dynamic Mechanical Analysis (DMA) can provide valuable information regarding rheological properties such as viscosity, storage modulus and loss modulus data, and Payne effect (Essabir et al., ; Saba et al., ; Barczewski et al., b). In the case of our study, it was carried out to evaluate the reinforcing nature of the biofiller and to confirm the results of the static tensile test.
In order to understand the changes in polymer composites occurring due to the reinforcing effect of fillers, many theories have been proposed to explain the Payne effect, e.g., clustering of particles in the network in the form of clusters or through physically stuck domains due to filler-matrix interfacial interactions (Robertson and Wang, ). It should be noted here that a well-developed filler structure does not always correlate well with improved performance of the composite, as the tendency of the filler to aggregate can be misunderstood in terms of its correct dispersion within the polymer matrix (Jordan et al., ). Therefore, an additional factor was established to estimate the behavior of the filler in the polymer matrix, namely the filler volume fraction, which compares the storage modulus of the unfilled and filled system with respect to the volume fraction of filler in the matrix. The study described (Cichosz et al., ) shows that both the Payne effect and the cellulose filler capacity factor, although not in all samples considered, indicate the possibility of a reinforcing nature of the fibers, which is not a common result.
Summarizing at this stage, it should be emphasized that the effect of polymer matrix strengthening is a very complex phenomenon. Apart from the fact that it depends on good distribution of the filler and its structure in the polymer matrix, other factors, e.g., filler-polymer matrix adhesion, properties at the phase boundary, as well as possible entanglements, are also of great importance (Gurovich et al., ).
What should be emphasized is that the observed strengthening effect, according to the literature, is a general resultant of two different mechanisms occurring simultaneously; the strengthening effect of the polymer matrix by the filler, as well as the result of interfacial bonding between cellulose and ethylene-norbornene copolymer (Barczewski et al., ).
In addition, the materials described in the cited articles are extremely promising considering the potential use of biopolymer composites in common healthcare applications due to the fact that ethylene-norbornene copolymer is widely used in this field. As a polymer matrix, it has high purity, excellent barrier properties and can be sterilized by all known methods. In addition, it is widely known for its excellent resistance to aqueous and polar organic media, good biocompatibility, and ability to reproduce fine structures, making it an interesting material for medical applications. Furthermore, its ease of fabrication provides molding possibilities that were not available, for example, for glass products (mainly used in the past). Therefore, plant fiber-based polymeric materials described in the cited studies may find potential applications in areas related to medical devices, drug delivery, in the manufacture of trays, pharmaceutical blister packs, or other items in contact with the body. Nevertheless, this material still needs to be well optimized in the future.
For biomedical applications, it is an essential requirement to assess the biocompatibility of materials and verify their interaction with cells, especially for applications where the material needs to remain in contact with living tissue and should not cause any cytotoxic or other side effects. Cellulose offers unique features of biodegradability, biocompatibility, low production cost as compared to synthetic biopolymers, abundance, sustainable resources, nontoxicity, and excellent mechanical properties. These features offer potential as bioresorbable polymers that plays an increasingly important role in biomedical applications due to their unique ability to be resorbed entirely in pre-designed time frames ranging from months to a few years.
Tissue engineering is known as an interdisciplinary field that applies the principles of engineering and life sciences toward the development of smart biological substitutes that potentially restore, maintain, and improve tissue functions that have malfunctioned (Table 6). The tissue engineering field generally utilizes biomaterials to develop constructs for intended medical interventions. Such constructs are to be exposed to living biological entities in the human body, from biomolecules and physiological fluids to cells, up to tissues and organs. In terms of physical properties, regenerative tissue material must possess optimal strength, e.g. compressive strength for bone tissue engineering, or tensile strength for artificial blood vessels and other soft tissue repairs. On the other hand, chemical considerations such as the surface chemistry of the materials are crucial, and the selection of materials must be rendered for specific application purposes. For instance, it is possible to tune porosity, thickness, and interconnectivity of nanocellulosic materials without compromising the mechanical properties for tissue scaffold production (Bäckdahl et al. ). For tissue engineering, cellulose as an additive or as primary scaffold material should have mechanical properties matching real tissues (Farzamfar et al. ; Hasan et al. ), promote porous structures for scaffolds (Hoo et al. ), or provide anchoring sites for osteoblasts (Gouma et al. ), and fibroblasts (Taokaew et al. ). The most commonly used cellulose derivatives for tissue engineering include cellulose acetate (Farzamfar et al. ), hydroxyethyl cellulose (Zulkifli et al. ), hydroxypropyl cellulose (Hoo et al. ), cellulose sulfate (Palaninathan et al. ), carboxymethyl cellulose (Hasan et al. ), methyl cellulose (Zhuo et al. ), and ethyl cellulose (Mao et al. a).
Table 6 A summary of cellulose-based biomaterials for major biomedical applicationsFull size table
One of the ubiquitous usages of biomaterials in tissue engineering is in the production of a biologically compatible scaffold that will support the attachment, proliferation, and differentiation of living cells that contribute to the promotion of tissue regeneration in vitro and in vivo conditions. Mammalian cells are not able to attach to the cellulosic surfaces used in artificial tissue scaffolds due to their hydrophilic nature and low non-specific protein adsorption. However, cell adhesion to substrate surfaces in cellulosic materials can be improved by the addition of matrix ligands. For example, ionic charges can be added to the cellulose membranes to adsorb collagen on the membrane surfaces, which can promote cellular adhesion (Courtenay et al. ). The positively charged BC has been applied, in the absence of proteins, to enhance cell attachment (Courtenay et al. ). BC is a biomaterial with a huge potential in dental and oral applications (Canas-Gutierrez et al. ). Recently, cost-effective and user-friendly functional biopolymeric-based materials have been used as a promising tool for developing, repairing, and regenerating functional tissues and organs in the human body. The use of cellulosic composites has been proposed in developing scaffold constructs that can be implanted in patients to replace failing or malfunctioning organs. Moreover, the inclusion of the appropriate reinforcement material for tissue-engineered biocomposite scaffolds is a significant factor in improving its characteristics and sustained biocompatibility. The use of cellulosic materials as reinforcement in biocomposites is now a fast-growing field, on account of their property enhancing capabilities (Ao et al. ; Sajjad et al. ). For instance, cellulosic fibers have been demonstrated recently to improve the formidability of biocomposite scaffolds in bone tissue engineering applications due to their unique structure (Mao et al. b). In addition, microfibrillated cellulose remarkably increases the surface area, and its interfibrillar hydrogen bonds facilitate network formation, which is desirable in bone tissue engineering (Ioniță et al. ). Moreover, CMC stimulates adhesion, spreading, and migration of mouse fibroblasts in vitro (Adachi et al. ; Aoshima and Jo ). Also, the presence of CMC decreases osteoclastogenesis by murine bone marrow progenitors (Agis et al. ), but increases osteoblast differentiation (Qi et al. ). Hydroxyethyl cellulose is a non-ionic, water-soluble polymer, and has a β-glucose linkage, which makes it a suitable candidate for tissue engineering applications. Hydroxyethyl cellulose increases cell viability and substantially stimulates cell growth (Tohamy et al. ). It also significantly enhances cell proliferation at high concentrations of hydroxyethyl cellulose (Chahal et al. ).
The appropriate mechanical properties of biomedical devices and materials are essential and very specific to the nature of the application area. For example, the elastic modulus of the material needs to be close to the medium and/or tissue that it is replacing or reinforcing. Nanocrystalline cellulose can be a promising material for cell attachment and proliferation due to its excellent mechanical properties and biocompatible nature. One particular advantage of using nanocrystalline cellulose is the fibrillar high aspect ratio building blocks, which construct a natural fiber network of fibrils or nanorods that is held together by hydrogen bonding and mechanical entanglement. Such a network could be even further reinforced mechanically by cross-linking the individual nanofibers. There are numerous cellular species cultured on nanocellulose biomaterials such as hydrogels, electrospun nanofibers, sponges, composites, and membranes (Luo et al. ). Among the sources of nanocellulose, bacterial nanocellulose is believed to be the most popular choice for cell culture due to its high porosity, biodegradability, and low toxicity (Halib et al. ). Usually, the rate of scaffold degradation under a given condition is an important issue as it should match the time of tissue formation to ensure the injured tissue is completely replaced by healthy tissue, and its function is restored.
The wound healing process involves an elaborate series of biological phenomena to restore barrier functionality, prevent dehydration, and reduce the risk of bacterial infection. Burn wounds and skin grafting require the development of novel wound dressing materials. Cellulose-based polymers have a high potential for wound dressing applications (Table 6). As wound dressing material, they should promote water retention or high water absorption capacity (Wutticharoenmongkol et al. ) or promote porosity and dryness that abhors bacterial attachment (Henschen et al. ). Here, the cellulosic material must be shaped like a sheet and used as a cover on wounds. It is highly beneficial to make drug-loaded cellulose-based bandages (Fan et al. ). Nanocellulose has excellent potential for wound healing applications, based on its moisture absorption and water retention ability that can be implemented over the wound itself, to contribute towards lowering inflammatory responses and promoting fibroblast proliferation in the wound healing cascade (Wang et al. ). Nanofibrillar cellulose is an ideal matrix for wound healing due to its high surface area to volume ratio, high water-holding ability, and high porosity. Moreover, its structure allows to mimic the architecture of the extracellular matrix or tissue/organs. Nanofibrillar cellulose hydrogel is a novel material for controlling excessive wound contraction in vivo and in vitro (Nuutila et al. ). Nanofibrillar cellulosics such as CMC and CA are the most promising wound dressing cellulosic materials that have been used in the treatment of burns and ulcers due to biocompatibility with mucous membrane and skin, biodegradability, non-toxicity, low immunogenicity, high water bonding affinity, and swelling capacity (Gomaa et al. ; Hakkarainen et al. ). Oxidized cellulose nanofiber is also appropriate for wound healing applications because of its substantial water absorption capacity and well-dispersed cellulose fibrils (Shefa et al. ).
Using CMC in wound healing requires some modifications to decrease the consequent pain burden in patients. A low level of localized pain, postoperative bleeding, and synechia have been reported for dissolvable CMC foam dressing (Szczygielski et al. ). Dissolvable CMC foam can also be used as wound dressing after sinus surgery due to the observed low levels of postoperative bleeding and synechia formation during application (Szczygielski et al. ). Nanocomposites based on BC are prepared by the direct introduction of magnetic nanoparticles within the cellulose culture medium for efficient chronic wound healing. Bionanocomposites containing plant CNC have been reported to be suitable wound healing templates for accelerating tissue regeneration (Singla et al. ). CA is also a suitable candidate in biocomposites for wound healing scaffold upon developing electrospun nanofibers (Wutticharoenmongkol et al. ). Hydrophilicity and bioactivity of CA enables cellular interaction between CA and fibroblasts, which consequently promotes cell proliferation (Gomaa et al. ).
BC is an appealing candidate for wound healing applications based on its favorable characteristics, such as biocompatibility, nontoxicity, and mechanical stability. Furthermore, BC provides a moist environment for the wound, hence enhancing the healing process (Sulaeva et al. ; Zmejkoski et al. ). However, BCs provide a suitable environment on-site as wound dressing materials, but the pH conditions can affect their contribution to the healing process (Shao et al. a). Different materials have been incorporated to develop BC-based biomaterials with enhanced properties to be suitable for wound dressing (Qiu et al. ). BC-montmorillonite-reinforced composites have been developed as wound dressing and regeneration materials for therapeutic applications without any side effects (Ul-Islam et al. ). BC-chitosan membranes show antibacterial activity and favorably low cytocompatibility for wound dressing (Lin et al. ). BC-based membranes show significant epithelialization and regeneration of the skin, faster than the commercial wound dressing product, Tegaderm&#; (Lin et al. ). Besides, the BC membrane accelerates the wound healing process in a burn model system through the regulation of angiogenesis and connective tissue formation (Kwak et al. ). BC-based hydrogel microparticles have been used as a dressing material for coverage of partial-thickness burn wounds both in vitro and in vivo (Pandey et al. ). Oxidized BC is another kind of cellulosic materials, which is appropriate for wound healing since it possesses considerable water absorption capacity, antibacterial effect, and well-dispersed cellulose fibrils (Wu et al. ).
A drug delivery system is defined as the release of drugs at an appropriate time, to specifically targeted organs in a specified amount. Drug delivery systems transfer drugs to the desired organs, tissues, or cells, where the transfer mechanism can be controlled to respond to environmental stimuli such as light, temperature, pH, chemical actions, and electric and magnetic fields. Cellulose has a long history of application in the pharmaceutical industry, where it has been used as a tablet-coating when blended with various excipients for oral administration. Despite an extended history of use in tableting, there is still ongoing research on the potential use of cellulose and its derivatives in advanced drug-loaded systems in terms of the rate of tablet dissolution as appropriate excipients or extended drug release as novel drug carriers (Table 6) (Abeer et al. ; Yan et al. ). As a drug delivery system, cellulosic materials should promote controllable diffusive properties and dissolvability. For instance, cellulose and its derivatives have been observed to exhibit definite drug delivery patterns by instant, controlled, or delayed-release in oral dosage forms (Godakanda et al. ; Jeddi and Mahkam ). Furthermore, the natural resistance of cellulosic materials to the acidic environment of the stomach makes them very practical to use as enteric coatings on capsules or tablets (Guo et al. ).
Extemporaneously, compounded medicines are used when a needed dose or dose form is commercially inaccessible, or when a particular dosing regime is required. Powdered cellulose and MCC are used as adsorbents, capsule diluents, and thickening stabilizing agents in compounded medicines (Marques-Marinho and Vianna-Soares ). MCC shows viscoelastic behavior and sensitivity to the strain rate. In high-speed tableting, the time for plastic deformation is limited, and hence, in this case, elastic effects are more significant (Roberts and Rowe ). Thus, in the formulation design and dosing, dependency of MCC to the strain rate should be considered (Thoorens et al. ).
CNFs possess a considerable potential in biomedicine as carrier for controlled drug delivery because of their suitable flexibility, conducive elasticity, low density, low toxicity, and relatively reactive surface, that can be used for grafting specific groups, in addition to being renewable and cheap. The rheological, barrier, and physicochemical characteristics of CNFs allow them to stabilize oil&#;water and air&#;water interfaces. Moreover, CNFs&#; high surface area per unit mass provides stabilization of nanoparticles and a higher probability for positive molecular interaction with poorly soluble drugs. CNFs have been used as stabilizers for crystalline drug nanoparticles, as matrix former to obtain a long-lasting sustained drug release over several weeks, and as film former with immediate release properties for poorly soluble drug (Löbmann and Svagan ). CNFs can generally be converted into aerogel form during drug adsorption and subsequent freeze-drying (Bhandari et al. ). Plant-based CNFs have been successfully used as an injectable drug-releasing hydrogel in mice, demonstrating the potential application of CNFs as a matrix for controlled release or targeted local delivery of drug compounds in humans (Laurén et al. ).
CA nanofiber mats have been used mainly in diverse pharmaceutical applications due to their advantageous characteristics, like high shear strength and shear modulus, biocompatibility, regenerative properties, high affinity with other substances, biodegradability, and suitable flexural and tensile strength. In particular, CA-based drug-loaded nanofibers have received considerable attention in the development of topical and transdermal drug delivery systems (Yu et al. ). Besides, cellulose acetate phthalate is a novel material that provides the most efficient solution for pH-controlled drug release. One of the decisive applications of cellulose acetate phthalate is in microencapsulation, which is utilized in an aqueous or organic medium (Wan and Chui ). Cellulose acetate phthalate electrospun fibers facilitate resistance to HIV infections. These fibers, even after dissolution, are nontoxic for vaginal epithelial cells and vaginal lactobacilli. These fibers are suitable for loading anti-HIV drugs and in preventing HIV infection during sexual intercourse (Huang et al. ). Typically, microencapsulation with cellulose acetate phthalate has been done by coacervation phase separation, spray-drying, and extrusion methods (Wan and Chui ).
One of the most prevalent hydrophilic biodegradable polymers that has been used in controlled-release formulations and that has been approved by the United States Food and Drug Administration (FDA), is hydroxy propyl methyl cellulose (Hu et al. ). Injectable chitosan/glycerophosphate thermosensitive solutions containing vancomycin-loaded hydroxy propyl methyl cellulose microparticles are produced for the local treatment of osteomyelitis (Mahmoudian and Ganji ). The porous and spongy structure of a hydroxyl propyl methyl cellulose hydrogel allows for a long-term release profile in vitro, which provides excellent potential for usage in sustained antibiotic delivery (Mahmoudian and Ganji ).
For more information, please visit cellulose distributor.