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22 pages, 7250 KiB

Open AccessArticle

Ionic Liquid Agar–Alginate Beads as a Sustainable Phenol Adsorbent

by Nihal Yasir, Amir Sada Khan, Muhammad Faheem Hassan, Taleb H. Ibrahim, Mustafa I. Khamis and Paul Nancarrow

Polymers 2022, 14(5), 984; https://doi.org/10.3390/polym14050984 - 28 Feb 2022

Cited by 8 | Viewed by 2600

Abstract

Cleaning wastewater containing low concentrations of phenolic compounds is a challenging task. In this work, agar–alginate beads impregnated with trihexyltetradecylphosphonium bromide ([P₆₆₆₁₄][Br]) ionic liquid adsorbent were synthesized as a potential adsorbent for such applications. FTIR, TGA, SEM, EDX and PZC studies [...] Read more.

Cleaning wastewater containing low concentrations of phenolic compounds is a challenging task. In this work, agar–alginate beads impregnated with trihexyltetradecylphosphonium bromide ([P₆₆₆₁₄][Br]) ionic liquid adsorbent were synthesized as a potential adsorbent for such applications. FTIR, TGA, SEM, EDX and PZC studies were performed to characterize and understand the physicochemical properties of the adsorbent. The Fourier transformation infrared spectroscopy (FTIR) study showed that [P₆₆₆₁₄][Br] ionic liquid was effectively incorporated into the agar–alginate structure. TGA and SEM confirmed comparative enhanced thermal stability and porous surface, respectively. Chemical reaction rate-altering parameters, i.e., pH, contact time, initial phenol concentration and temperature, are optimized at highest phenol removal. It was found that the maximum phenol adsorption capacity and highest removal efficiency by the adsorbent occurred at pH 2, initial phenol concentration of 150 mg/L, beads dosage of 6 mg/mL and contact time of 2 h with values of 16.28 mg/g and 65.12%, respectively. The pseudo-second order model fitted the adsorption kinetics well, and the Freundlich isotherm model gave the experimental data the best fit. Analysis of thermodynamic data demonstrated that the adsorption process is fundamentally exothermic in nature, and low temperature favors spontaneity of the chemical reaction. Regeneration studies indicated that the adsorbent can at least be used for four cycles in such applications without any considerable loss in adsorption efficiency. Full article

(This article belongs to the Special Issue Functional Alginate-Based Materials)

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14 pages, 662 KiB

Open AccessEditor’s ChoiceArticle

Effect of Nanoencapsulated Alginate-Synbiotic on Gut Microflora Balance, Immunity, and Growth Performance of Growing Rabbits

by Nesrein M. Hashem, Nourhan S. Hosny, Nagwa I. El-Desoky and Mohamed G. Shehata

Polymers 2021, 13(23), 4191; https://doi.org/10.3390/polym13234191 - 30 Nov 2021

Cited by 11 | Viewed by 2559

Abstract

A synbiotic comprising Saccharomyces cerevisiae yeast (SCY) and Moringa oleifera leaf extract (MOLE) has been encapsulated using nanotechnology. This duo is used as a dietary supplement for growing rabbits. Physicochemical analyses, in vitro antimicrobial activity, and gastrointestinal system evaluation were used to evaluate [...] Read more.

A synbiotic comprising Saccharomyces cerevisiae yeast (SCY) and Moringa oleifera leaf extract (MOLE) has been encapsulated using nanotechnology. This duo is used as a dietary supplement for growing rabbits. Physicochemical analyses, in vitro antimicrobial activity, and gastrointestinal system evaluation were used to evaluate the quality of the nanofabricated synbiotic. The in vivo study was conducted using 40-day-old male growing rabbits (n = 16 rabbits/group) to evaluate the effect of the nanofabricated synbiotic on the health and growth performance of examined rabbits. Rabbits were equally allocated into four groups; (a) NCS, which received a basal diet supplemented with a noncapsulated 11 × 10¹² CFU SCY + 0.15 g MOLE/kg diet, (b) LCS: those receiving a nanoencapsulated 5.5 × 10¹² CFU SCY + 0.075 g MOLE/kg diet, (c) HCS: those receiving an 11 × 10¹² CFU SCY + 0.15 g MOLE/kg diet, and (d) CON: those receiving a basal diet without treatment (control). The treatments continued from day 40 to day 89 of age. During the experimental period, growth performance variables, including body weight (BW), feed consumption, BW gain, and feed conversion ratio were recorded weekly. Blood samples were collected on day 40 of age and immediately before the start of the treatments to confirm the homogeneity of rabbits among groups. On day 89 of age, blood samples, intestinal, and cecal samples were individually collected from eight randomly selected rabbits. The size and polydispersity index of the nanofabricated synbiotic were 51.38 nm and 0.177, respectively. Results revealed that the encapsulation process significantly improved yeast survival through the gastrointestinal tract, specifically in stomach acidic conditions, and significantly increased in vitro inhibitory activities against tested pathogens. Furthermore, treatments had no negative effects on hematobiochemical variables but significantly improved levels of blood plasma, total protein, and insulin-like growth factor-l. Compared to the CON, NCS, and LCS treatments, the HCS treatment increased the amount of intestinal and cecal yeast cells (p < 0.05) and Lactobacillus bacteria (p < 0.05) and decreased number of Salmonella (p < 0.05) and Coliform (p = 0.08) bacteria. Likewise, both LCS and HCS significantly improved the small intestine and cecum lengths compared to CON and NCS. The HCS treatment also significantly improved BW gain and feed conversion compared to CON treatment, whereas the NCS and LCS treatments showed intermediate values. Conclusively, the nanoencapsulation process improved the biological efficiency of the innovative synbiotic used in this study. A high dose of encapsulated synbiotic balanced the gut microflora, resulting in the growth of rabbits during the fattening period. Full article

(This article belongs to the Special Issue Functional Alginate-Based Materials)

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19 pages, 10966 KiB

Open AccessEditor’s ChoiceArticle

Preliminary Study for the Preparation of Transmucosal or Transdermal Patches with Acyclovir and Lidocaine

by Cristina-Adela Marioane, Mădălin Bunoiu, Mădălina Mateescu, Paula Sfîrloagă, Gabriela Vlase and Titus Vlase

Polymers 2021, 13(20), 3596; https://doi.org/10.3390/polym13203596 - 19 Oct 2021

Cited by 7 | Viewed by 2057

Abstract

The present study aimed to prepare and evaluate patches for the controlled release of lidocaine/acyclovir and the binary mixture between lidocaine: acyclovir in the oral cavity. Mucoside adhesive patches containing 12.5 mg/cm² lidocaine/acyclovir or binary mixture base were developed by a solvent [...] Read more.

The present study aimed to prepare and evaluate patches for the controlled release of lidocaine/acyclovir and the binary mixture between lidocaine: acyclovir in the oral cavity. Mucoside adhesive patches containing 12.5 mg/cm² lidocaine/acyclovir or binary mixture base were developed by a solvent casting method using sodium alginate, polyvinylpyrrolidone (PVP), glycerol (Gly), polyvinyl alcohol (PVA), and Span 80 (S). Binary mixtures between all components were prepared before the patches’ formulation in order to be able to check the substance compatibility. All formulated patches were analyzed by FT-IR spectroscopy, UV-Vis analysis, thermogravimetry (TGA), and scanning electron microscopy (SEM). FT-IR and TGA analyses were also used to check compatibility between binary mixtures. The study establishes which membranes are indicated in the controlled release of lidocaine/acyclovir and those membranes that contain both active principles. Membranes based on alginate, PVP, and PVA can be used to release the active substance. Simultaneously, membranes with SPAN used as a gelling agent were excluded due to the interaction with the active substance. The following membranes composition have been chosen for lidocaine release: Alginate:Gly and Alginate:Gly:PVP. At the same time, the following membrane compositions were chosen for acyclovir membranes: Alginate:Gly:PVP and Alginate:PVA:Gly. Both active substances could be included to obtain a homogeneous distribution only in the membrane based on alginate, PVA, and Gly. Full article

(This article belongs to the Special Issue Functional Alginate-Based Materials)

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12 pages, 5288 KiB

Open AccessEditor’s ChoiceArticle

Rheological Properties of Aqueous Sodium Alginate Slurries for LTO Battery Electrodes

by Christina Toigo, Milan Kracalik, Elke Bradt, Karl-Heinz Pettinger and Catia Arbizzani

Polymers 2021, 13(20), 3582; https://doi.org/10.3390/polym13203582 - 17 Oct 2021

Cited by 8 | Viewed by 2700

Abstract

Rheological properties of electrode slurries have been intensively studied for manifold different combinations of active materials and binders. Standardly, solvent-based systems are under use, but a trend towards water-based electrode manufacturing is becoming more and more important. The different solvent is beneficial in [...] Read more.

Rheological properties of electrode slurries have been intensively studied for manifold different combinations of active materials and binders. Standardly, solvent-based systems are under use, but a trend towards water-based electrode manufacturing is becoming more and more important. The different solvent is beneficial in terms of sustainability and process safety but is also accompanied by some disadvantages such as extraction of residual humidity and a higher complexity concerning slurry stability. Li₄Ti₅O₁₂ (LTO) active material provides good long-term stability and can be processed in aqueous solutions. Combining the LTO active material with sodium alginate (SA) as a promising biobased polymer binder reveals good electrochemical properties but suffers from bad slurry stability. In this work, we present a comprehensive rheological study on material interactions in anode slurries consisting of LTO and SA, based on a complex interaction of differentially sized materials. The use of two different surfactants—namely, an anionic and non-ionic one, to enhance slurry stability, compared with surfactant-free slurry. Full article

(This article belongs to the Special Issue Functional Alginate-Based Materials)

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13 pages, 24165 KiB

Open AccessArticle

Self-Healing, Stretchable, Biocompatible, and Conductive Alginate Hydrogels through Dynamic Covalent Bonds for Implantable Electronics

by Yeonsun Choi, Kyuha Park, Heewon Choi, Donghee Son and Mikyung Shin

Polymers 2021, 13(7), 1133; https://doi.org/10.3390/polym13071133 - 02 Apr 2021

Cited by 32 | Viewed by 4841

Abstract

Implantable electronics have recently been attracting attention because of the promising advances in personalized healthcare. They can be used to diagnose and treat chronic diseases by monitoring and applying bioelectrical signals to various organs. However, there are challenges regarding the rigidity and hardness [...] Read more.

Implantable electronics have recently been attracting attention because of the promising advances in personalized healthcare. They can be used to diagnose and treat chronic diseases by monitoring and applying bioelectrical signals to various organs. However, there are challenges regarding the rigidity and hardness of typical electronic devices that can trigger inflammatory reactions in tissues. In an effort to improve the physicochemical properties of conventional implantable electronics, soft hydrogel-based platforms have emerged as components of implantable electronics. It is important that they meet functional criteria, such as stretchability, biocompatibility, and self-healing. Herein, plant-inspired conductive alginate hydrogels composed of “boronic acid modified alginate” and “oligomerized epigallocatechin gallate,” which are extracted from plant compounds, are proposed. The conductive hydrogels show great stretchability up to 500% and self-healing properties because of the boronic acid-cis-diol dynamic covalent bonds. In addition, as a simple strategy to increase the electrical conductivity of the hydrogels, ionically crosslinked shells with cations (e.g., sodium) were generated on the hydrogel under physiological salt conditions. This decreased the resistance of the conductive hydrogel down to 900 ohm without trading off the original properties of stretchability and self-healing. The hydrogels were used for “electrophysiological bridging” to transfer electromyographic signals in an ex vivo muscle defect model, showing a great bridging effect comparable to that of a muscle-to-muscle contact model. The use of plant-inspired ionically conductive hydrogels is a promising strategy for designing implantable and self-healable bioelectronics. Full article

(This article belongs to the Special Issue Functional Alginate-Based Materials)

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20 pages, 3244 KiB

Open AccessArticle

Performance Evaluation of a Novel Biosourced Co-Processed Excipient in Direct Compression and Drug Release

by Rihab Benabbas, Noelia M. Sanchez-Ballester, Adrien Aubert, Tahmer Sharkawi, Bernard Bataille and Ian Soulairol

Polymers 2021, 13(6), 988; https://doi.org/10.3390/polym13060988 - 23 Mar 2021

Cited by 9 | Viewed by 2887

Abstract

This study exposes the potential usefulness of a new co-processed excipient, composed of alginic acid and microcrystalline cellulose (Cop AA-MCC), for the preparation of immediate drug release tablets by direct compression. Evaluation of the physical and mechanical properties as well as the disintegration [...] Read more.

This study exposes the potential usefulness of a new co-processed excipient, composed of alginic acid and microcrystalline cellulose (Cop AA-MCC), for the preparation of immediate drug release tablets by direct compression. Evaluation of the physical and mechanical properties as well as the disintegration behavior of Cop AA-MCC in comparison to commercial co-processed excipients (Cellactose^®, Ludipress^®, Prosolv^® SMCC HD90 and Prosolv^® ODT) and to the physical mixture of the native excipients (MCC and AA), was carried out. The obtained results illustrate the good performance of Cop AA-MCC in terms of powder flowability, tablet tensile strength, compressibility, and disintegration time. Although, this new co-processed excipient showed a slightly high lubricant sensitivity, which was explained by its more plastic than fragmentary deformation behavior, it presented a low lubricant requirement due to the remarkably low ejection force observed during compression. Compression speed and dwell time seemed not to affect significantly the tabletability of Cop AA-MCC. The study exposed evenly the performance of Cop AA-MCC compared to Prosolv^® ODT, in terms of tabletability and dissolution rate of Melatonin. Cop AA-MCC presented comparable hardness, lower dilution potential, higher lubricant sensitivity, lower ejection force, and faster Melatonin’s release time than Prosolv^® ODT. In summary, Cop AA-MCC exhibited interesting physical, mechanical, and biopharmaceutical properties, which demonstrate its concurrence to commercially available co-processed excipients. Furthermore, the simplicity of its composition and the scalability of its elaboration makes this multifunctional excipient highly recommended for direct compression. Full article

(This article belongs to the Special Issue Functional Alginate-Based Materials)

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13 pages, 2368 KiB

Open AccessArticle

Mechanical Stabilization of Alginate Hydrogel Fiber and 3D Constructs by Mussel-Inspired Catechol Modification

by Kyoungryong Kim, Jae Hyuk Choi and Mikyung Shin

Polymers 2021, 13(6), 892; https://doi.org/10.3390/polym13060892 - 14 Mar 2021

Cited by 14 | Viewed by 3640

Abstract

Alginate is a representative biocompatible natural polymer with low cost for a variety of biomedical applications, such as wound dressing, drug delivery systems, tissue scaffolds, and 3D bioprinting. Particularly, the rapid and facile gelation of alginate via ionic interactions with divalent cations has [...] Read more.

Alginate is a representative biocompatible natural polymer with low cost for a variety of biomedical applications, such as wound dressing, drug delivery systems, tissue scaffolds, and 3D bioprinting. Particularly, the rapid and facile gelation of alginate via ionic interactions with divalent cations has been used for in situ 3D hydrogel fiber formation, which is potentially applicable to engineering cell alignment. However, challenges in enhancing the mechanical properties of alginate hydrogel fibers under physiological conditions are unresolved because of their fast dissociation by ion exchange. Herein, we report a stabilization strategy for alginate hydrogel fibers through mussel-inspired catechol chemistry, which involves inter-catechol crosslinking within a few minutes under basic conditions. The fabrication of catechol-tethered alginate hydrogel fibers through wet-spinning enabled the design of mechanically strong 3D constructs consisting of fibers. Catechol-to-quinone oxidation followed by covalent crosslinking enhanced the tensile strength of a single fiber. Additionally, the ‘gluing’ capability of the catechol stabilized the interface among the fibers, thus retaining the shape fidelity of the 3D constructs and encapsulating the cell density during culture. Our findings will be useful for designing bioink materials specialized in fibrous-type tissue scaffolds with mechanical stability. Full article

(This article belongs to the Special Issue Functional Alginate-Based Materials)

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11 pages, 3540 KiB

Open AccessArticle

Alginate as Dispersing Agent for Compounding Natural Rubber with High Loading Microfibrillated Cellulose

by Goragot Supanakorn, Nanthaphak Varatkowpairote, Siriporn Taokaew and Muenduen Phisalaphong

Polymers 2021, 13(3), 468; https://doi.org/10.3390/polym13030468 - 01 Feb 2021

Cited by 17 | Viewed by 3871

Abstract

Natural rubber (NR) reinforced with high loading of microfibrillated cellulose (MFC) was fabricated in the presence of sodium alginate as a thickening and dispersing agent in NR latex. The tensile strength and Young’s moduli of the 50% wt. MFC loading-NR composites were 13.6 [...] Read more.

Natural rubber (NR) reinforced with high loading of microfibrillated cellulose (MFC) was fabricated in the presence of sodium alginate as a thickening and dispersing agent in NR latex. The tensile strength and Young’s moduli of the 50% wt. MFC loading-NR composites were 13.6 and 1085.7 MPa, which were about 11.3- and 329-times enhanced compared with those of the neat NR film. The maximum elongation at 313.3% was obtained from 30% MFC loading, which was a 3.3-fold increase of that of the NR film. The thermal stability of MFC–NR films was slightly reduced, while the glass transition temperature remained unchanged at −64 °C. The MFC–NR films exhibited high water adsorption ability, toluene resistance, and biodegradability. Full article

(This article belongs to the Special Issue Functional Alginate-Based Materials)

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15 pages, 4984 KiB

Open AccessArticle

Functionalization of an Alginate-Based Material by Oxidation and Reductive Amination

by Ronny G. Huamani-Palomino, Bryan M. Córdova, Elvis Renzo Pichilingue L., Tiago Venâncio and Ana C. Valderrama

Polymers 2021, 13(2), 255; https://doi.org/10.3390/polym13020255 - 14 Jan 2021

Cited by 16 | Viewed by 4091

Abstract

This research focused on the synthesis of a functional alginate-based material via chemical modification processes with two steps: oxidation and reductive amination. In previous alginate functionalization with a target molecule such as cysteine, the starting material was purified and characterized by UV-Vis, ¹ [...] Read more.

This research focused on the synthesis of a functional alginate-based material via chemical modification processes with two steps: oxidation and reductive amination. In previous alginate functionalization with a target molecule such as cysteine, the starting material was purified and characterized by UV-Vis, ¹H-NMR and HSQC. Additionally, the application of FT-IR techniques during each step of alginate functionalization was very useful, since new bands and spiked signals around the pyranose ring (1200–1000 cm⁻¹) and anomeric region (1000–750 cm⁻¹) region were identified by a second derivative. Additionally, the presence of C₁-H₁ of β-D-mannuronic acid residue as well as C₁-H₁ of α-L-guluronic acid residue was observed in the FT-IR spectra, including a band at 858 cm⁻¹ with characteristics of the N-H moiety from cysteine. The possibility of attaching cysteine molecules to an alginate backbone by oxidation and post-reductive amination processes was confirmed through ¹³C-NMR in solid state; a new peak at 99.2 ppm was observed, owing to a hemiacetal group formed in oxidation alginate. Further, the peak at 31.2 ppm demonstrates the presence of carbon -CH₂-SH in functionalized alginate—clear evidence that cysteine was successfully attached to the alginate backbone, with 185 μmol of thiol groups per gram polymer estimated in alginate-based material by UV-Visible. Finally, it was observed that guluronic acid residue of alginate are preferentially more affected than mannuronic acid residue in the functionalization. Full article

(This article belongs to the Special Issue Functional Alginate-Based Materials)

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20 pages, 6017 KiB

Open AccessArticle

Bacterial Nanocellulose-Enhanced Alginate Double-Network Hydrogels Cross-Linked with Six Metal Cations for Antibacterial Wound Dressing

by Mina Shahriari-Khalaji, Siyi Hong, Gaoquan Hu, Ying Ji and Feng F. Hong

Polymers 2020, 12(11), 2683; https://doi.org/10.3390/polym12112683 - 13 Nov 2020

Cited by 43 | Viewed by 3789

Abstract

Alginate (Alg) and bacterial nanocellulose (BNC) have exhibited great potential in biomedical applications, especially wound dressing. Non-toxicity and a moisture-maintaining nature are common features making them favorable for functional dressing fabrication. BNC is a natural biopolymer that promotes major advances to the current [...] Read more.

Alginate (Alg) and bacterial nanocellulose (BNC) have exhibited great potential in biomedical applications, especially wound dressing. Non-toxicity and a moisture-maintaining nature are common features making them favorable for functional dressing fabrication. BNC is a natural biopolymer that promotes major advances to the current and future biomedical materials, especially in a flat or tubular membrane form with excellent mechanical strength at hydrated state. The main drawback limiting wide applications of both BNC and Alg is the lack of antibacterial activity, furthermore, the inherent poor mechanical property of Alg leads to the requirement of a secondary dressing in clinical treatment. To fabricate composite dressings with antibacterial activity and better mechanical properties, sodium alginate was efficiently incorporated into the BNC matrix using a time-saving vacuum suction method followed by cross-linking through immersion in separate solutions of six cations (manganese, cobalt, copper, zinc, silver, and cerium). The results showed the fabricated composites had not only pH-responsive antibacterial activities but also improved mechanical properties, which are capable of acting as smart dressings. All composites showed non-toxicity toward fibroblast cells. Rat model evaluation showed the skin wounds covered by the dressings healed faster than by BNC. Full article

(This article belongs to the Special Issue Functional Alginate-Based Materials)

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Review

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26 pages, 45868 KiB

Open AccessReview

Collagen–Alginate Composite Hydrogel: Application in Tissue Engineering and Biomedical Sciences

by Tingyu Hu and Amy C. Y. Lo

Polymers 2021, 13(11), 1852; https://doi.org/10.3390/polym13111852 - 02 Jun 2021

Cited by 47 | Viewed by 8154

Abstract

Alginate (ALG), a polysaccharide derived from brown seaweed, has been extensively investigated as a biomaterial not only in tissue engineering but also for numerous biomedical sciences owing to its wide availability, good compatibility, weak cytotoxicity, low cost, and ease of gelation. Nevertheless, alginate [...] Read more.

Alginate (ALG), a polysaccharide derived from brown seaweed, has been extensively investigated as a biomaterial not only in tissue engineering but also for numerous biomedical sciences owing to its wide availability, good compatibility, weak cytotoxicity, low cost, and ease of gelation. Nevertheless, alginate lacks cell-binding sites, limiting long-term cell survival and viability in 3D culture. Collagen (Col), a major component protein found in the extracellular matrix (ECM), exhibits excellent biocompatibility and weak immunogenicity. Furthermore, collagen contains cell-binding motifs, which facilitate cell attachment, interaction, and spreading, consequently maintaining cell viability and promoting cell proliferation. Recently, there has been a growing body of investigations into collagen-based hydrogel trying to overcome the poor mechanical properties of collagen. In particular, collagen–alginate composite (CAC) hydrogel has attracted much attention due to its excellent biocompatibility, gelling under mild conditions, low cytotoxicity, controllable mechanic properties, wider availability as well as ease of incorporation of other biomaterials and bioactive agents. This review aims to provide an overview of the properties of alginate and collagen. Moreover, the application of CAC hydrogel in tissue engineering and biomedical sciences is also discussed. Full article

(This article belongs to the Special Issue Functional Alginate-Based Materials)

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