As a natural raw material to replace synthetic chemicals, cellulose and its derivatives are the most popular choices in the pharmaceutical industry. For drug delivery applications, cellulose is usually used as a cellulose nanocrystal (CNC). CNC-based hydrogels are widely utilized for drug delivery because drug molecules can be encapsulated in their pore-like structures. This study aims to develop CNC hydrogels for the delivery of doripenem antibiotics. CNC was obtained from jackfruit peel extraction, and alginate was used as a network polymer to produce hydrogels. Ionotropic gelation was used in the synthesis of CNC-alginate hydrogel composites. The maximum adsorption of doripenem by CNC was 65.7 mg/g, while the maximum adsorption by CNC-alginate was 98.4 mg/g. One of the most challenging aspects of drug delivery is predicting drug release from a solid matrix using simple and complex mathematical equations. The sigmoidal equation could represent the doripenem release from CNC, while the Ritger-Peppas equation could describe the doripenem release from CNC-Alginate. The biocompatibility testing of CNC and CNC-alginate against a 7F2 cell line indicates that both materials were non-toxic.
The current study sought to create graphene oxide-based superstructures for gastrointestinal drug delivery. Graphene oxide has a large surface area that can be used to load anti-cancer drugs via non-covalent methods such as surface adsorption and hydrogen bonding. To enhance the bio-applicability of graphene oxide, nano-hybrids were synthesized by encapsulating the graphene oxide into calcium alginate hydrogel beads through the dripping-extrusion technique. These newly developed bio-nanocomposite hybrid hydrogel beads were evaluated in structural analysis, swelling study, drug release parameters, haemolytic assay, and antibacterial activity. Doxorubicin served as a model drug. The drug entrapment efficiency was determined by UV-spectroscopy analysis and was found to be high at ⁓89% in graphene oxide hybrid hydrogel beads. These fabricated hydrogel beads ensure the drug release from a hybrid polymeric matrix in a more controlled and sustained pattern avoiding the problems associated with a non-hybrid polymeric system. The drug release study of 12 h shows about 83% release at pH 6.8. In vitro drug release kinetics proved that drug release was a Fickian mechanism. The cytotoxic effect of graphene oxide hybrid alginate beads was also determined by evaluating the morphology of bacterial cells and red blood cells after incubation. Additionally, it was determined that the sequential encapsulation of graphene oxide in alginate hydrogel beads hides its uneven edges and lessens the graphene oxide's negative impacts. Also, the antibacterial study and biocompatibility of fabricated hydrogel beads made them potential candidates for gastrointestinal delivery.
The primary aim of this study is to develop an economical, stable, and effective heterogeneous catalyst for wastewater remediation via the Fenton oxidation process. For this purpose, Fe3O4-montmorillonite alginate (FeMA) composite beads were synthesized by entrapping Fe3O4-montmorillonite in calcium alginate beads. The performance of the catalysts was evaluated via the Fenton degradation of ofloxacin (OFL), an antibiotic that is frequently detected in water bodies. The physiochemical properties of the FeMA composite beads were characterized using X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscope/energy dispersive X-ray (FESEM/EDX), Brunauer-Emmett-Teller (BET) analysis, Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA). FeMA composite beads were found to have a higher surface area, higher porosity, and better thermal stability compared to pristine alginate beads. The composite beads were subsequently used for Fenton degradation of ofloxacin (OFL) in an aqueous solution. The effects of Fe3O4-montmorillonite loading on alginate, FeMA composite beads dosage, initial solution pH, initial OFL concentration, different oxidants, H2O2 dosage, reaction temperature, and inorganic salts on Fenton degradation of OFL in aqueous solution was investigated. The results revealed that the percentage of OFL degradation reached about 80 % under optimized conditions, while the total organic carbon (TOC) removal reached about 53 %. The entrapment of Fe3O4-montmorillonite in alginate beads results in less iron ions leaching compared to previous observation, and the efficiency remains constant over the five cycles investigated. The kinetics of the Fenton degradation process are best fitted to the pseudo-first-order kinetic model. It is therefore believed that FeMA composite beads can be a promising material for wastewater remediation via the Fenton oxidation process.
Frequent droughts significantly affect agricultural productivity and highlight the need for effective solutions to improve water availability for crops. This study investigates the potential of chitosan-based hydrogels, biodegradable biopolymers known for their water-retaining properties, to improve soil moisture and promote plant growth during drought periods. Chitosan hydrogels were synthesized using Pluronic F127 and compared with chitosan and chitosan in combination with sodium alginate (CS/Alg-Na). Comprehensive chemical characterizations were performed by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) and field emission scanning electron microscopy (FESEM). The CS/Pl-F127 hydrogels showed high porosity and a water absorption capacity of 81.5 %, while the CS/Alg-Na exhibited a denser network with a capacity of 93.35 % and improved mechanical strength. Plants in the CS/Pl-F127 hydrogel had a shoot elongation rate of 5.9 mm/day on Day 9, which continued until Day 40. In contrast, shoot elongation in the CS/Alg-Na hydrogel peaked at 7.1 mm/day on Day 20 and maintained growth under drought conditions until Day 33. These results show that all chitosan-based hydrogels improve water use efficiency. CS/Alg-Na provides the best support for plant growth under drought conditions, followed by CS/Pl-F127 and pure chitosan.
The current study aimed at developing diethonolamine-modified high-methoxyl pectin (DMP)-alginate (ALG) based core-shell composites for controlled intragastric delivery of metformin HCl (MFM) by combined approach of floating and bioadhesion. DMP with degree of amidation of 48.72% was initially accomplished and characterized by FTIR, DSC and XRD analyses. MFM-loaded core matrices were then fabricated by ionotropic gelation technique employing zinc acetate as cross-linker. The core matrices were further coated by fenugreek gum (FG)-ALG gel membrane via diffusion-controlled interfacial complexation method. Various formulations demonstrated excellent drug encapsulation efficiency (DEE, 51-70%) and sustained drug eluting behavior (Q8h, 72-96%), which were extremely influenced by polymer-blend (ALG:DMP) ratios, low density additives (olive oil/magnesium stearate) and FG-ALG coating inclusion. The drug release profile of the core-shell matrices (F-7) was best fitted in zero-order kinetic model with case-II transport driven mechanism. It also portrayed outstanding gastroretentive characteristics. Moreover, the composites were analyzed for surface morphology, drug-excipients compatibility, thermal behavior and drug crystallinity. Thus, the developed composites are appropriate for controlled stomach-specific delivery of MFM for type 2 diabetes management.
The commercial application of liquid-state Pickering emulsions in food systems remains a major challenge. In this study, we developed a spray-dried Pickering emulsion powder using chitosan as a Pickering emulsifier and alginate as a coating material. The functionality of the powder was evaluated in terms of its oxidative stability, pH-responsiveness, mucoadhesivity, and lipid digestibility. The Pickering emulsion powder was oxidatively more stable than the conventional emulsion powder stabilized by gum Arabic. The powder exhibited pH-responsiveness, whereby it remained intact in acidic pH, but dissolved to release the emulsion in 'Pickering form' at near-neutral pH. The Pickering emulsion powder was also mucoadhesive and could be digested by lipase in a controlled manner. These findings suggested that the multi-functional Pickering emulsion powder could be a potential delivery system for applications in the food industry.
The presence of Cs(I) ions in nuclear wastewater becomes an important issue for the reason of its high toxicity. The development of adsorbent embedded metal-based catalysts that has sufficient adsorption capacity is expected for the removal of Cs(I) ions from contaminated water. This study tested the use of maghemite, titania and combined maghemite-titania polyvinyl alcohol (PVA)-alginate beads as an adsorbent to remove Cs(I) ions from aqueous solution with the variables of pH and initial concentration using batch experiments under sunlight. The results showed that the use of combined maghemite-titania PVA-alginate beads can have an efficiency of 93.1% better than the use of either maghemite PVA-alginate beads with an efficiency of 91.8% or titania PVA-alginate beads with an efficiency of 90.1%. The experimental data for adsorption of Cs(I) ions from aqueous solution with the initial concentrations of 50, 100 and 200 mg L(-1) on the surface of combined maghemite-titania PVA-alginate beads were well fit by the pseudo-second-order and Langmuir models. The optimal adsorption of Cs(I) ions from aqueous solution by combined maghemite-titania PVA-alginate beads under sunlight occurs at pH 8 with an initial Cs(I) ion concentration of 50 mg L(-1). The combined maghemite-titania PVA-alginate beads can be recycled at least five times with a slight loss of their original properties.
The presence of heavy metal and radionuclides in water bodies has been a long-lasting environmental problem which results in many undesirable consequences. In this framework, the biosorption process, which uses inexpensive and naturally produced material such as alginate, is an alternative technology in the environmental remediation. This review provides relevant and recent literature regarding the application of alginate and its derivatives on removal of various heavy metal ions and radionuclides. The effects of process variables such as solution pH, adsorbent dosage, metal ion concentration, contact time, temperature and co-existing ions used in batch studies in addition to kinetic, isothermal models as well as thermodynamic that fit the adsorption experimental data are critically discussed. This review also includes mechanisms involved during adsorption process. Furthermore, future research needs for the removal of contaminants by alginate-based materials with the aims of improving their adsorption performance and their practical applications are commented.
Use of alginate graft copolymers in oral drug delivery reduces dosage form manufacture complexity with reference to mixing or coating processes. It is deemed to give constant or approximately steady weight ratio of alginate to covalently attached co-excipient in copolymers, thereby leading to controllable matrix processing and drug release. This review describes various grafting approaches and their outcome on oral drug release behaviour of alginate graft copolymeric matrices. It examines drug release modulation mechanism of alginate graft copolymers against that of co-excipients in non-grafted formulations.
Metal removal potential of both alginate-immobilized and free-cells of Effective Microorganisms (EM-1™ Inoculant) was investigated in this study. Results revealed that removal of Cr(III), Cu(II) and Pb(II) followed a similar trend where alginate-immobilized EM were more efficient compared to free-cells of EM. For these metals, 0.940, 2.695 and 4.011 mg g(-1) of Cr(III), Cu(II) and Pb(II) were removed compared to only 0.160, 0.859 and 0.755 mg ml(-1) removed by free-cells, respectively. The higher efficiency of alginate-immobilized EM was primarily attributed to the alginate matrix. This was evident when both alginate-immobilized EM and plain alginate beads (without EM), were not significantly different in their removal efficacies. Presence of alginate also enhanced the use of the biosorbents as maximum metal sorption was achieved after 120 min as opposed to only 60 min for free-cells. EM per se in immobilized or free-cell forms did not enhance metal removal efficacy.
Although anionic polyelectrolyte hydrogel beads offer attractive adsorption of cationic dyes, phosphate adsorption is limited by electrostatic interactions. In this work, carboxymethyl cellulose (CMC)/sodium alginate (SA) hydrogel beads were modified with calcium carbonate (CaCO3) and/or bentonite (Be). The compatibility between CaCO3 and Be was proven by the homogeneous surface, as shown in the scanning electron microscopic images. Fourier-transform infrared and X-ray diffraction spectra further confirmed the existence of inorganic filler in the hydrogel beads. Although CMC/SA/Be/CaCO3 hydrogel beads attained the highest methylene blue and phosphate adsorption capacities (142.15 MB mg/g, 90.31 P mg/g), phosphate adsorption was significantly improved once CaCO3 nanoparticles were incorporated into CMC/SA/CaCO3 hydrogel beads. The kinetics of MB adsorption by CMC/SA hydrogel beads with or without inorganic fillers could be described by the pseudo-second-order model under chemical interactions. The phosphate adsorption by CMC/SA/Be/CaCO3 hydrogel beads could be explained by the Elovich model due to heterogeneous properties. The incorporation of Be and CaCO3 also improved the phosphate adsorption through chemical interaction since Langmuir isotherm fitted the phosphate adsorption by CMC/SA/Be/CaCO3 hydrogel beads. Unlike MB adsorption, the reusability of these hydrogel beads in phosphate adsorption reduced slightly after 5 cycles.
In this study, the synthesis and experimental theoretical evaluation of a new chitosan/alginate/hydrozyapatite nanocomposite doped with Mn2 and Fe2O3 for Cr removal was reported. The physicochemical properties of the obtained materials were analyzed using the following methods: SEM-EDX, XRD, FTIR, XPS, pH drift measurements, and thermal analysis. The adsorption properties were estimated based on equilibrium and adsorption kinetics measurements. The Langmuir, Freundlich and Temkin isotherms were applied to analyze the equilibrium data. The thermodynamic analysis of adsorption isotherms was performed. A number of equations and kinetic models were used to describe the adsorption rate data, including pseudo-first (PFOE) and pseudo-second (PSOE) order kinetic equations. The obtained test results show that the synthesized biomaterial, compared to pure chitosan, is characterized by greater resistance to high temperatures. Moreover, this biomaterial had excellent adsorption properties. For the adsorption of Cr (VI), the equilibrium state was reached after 120 min, and the sorption capacity was 455.9 mg/g. In addition, DFT calculations and NCI analyses were performed to get more light on the adsorption mechanism of Cr (VI) on the prepared biocomposite.
AlyQ from Persicobacter sp. CCB-QB2 is an alginate lyase with three domains - a carbohydrate-binding domain modestly resembling family 16 carbohydrate-binding module (CBM16), a family 32 CBM (CBM32) domain, and an alginate lyase domain belonging to polysaccharide lyase family 7 (PL7). Although AlyQ can also act on polyguluronate (poly-G) and polymannuronate (poly-M), it is most active on alginate. Studies with truncated AlyQ showed that the CBM32 domain did not contribute to enhancing AlyQ's activity under the assayed conditions. Nevertheless, it could bind to cleaved but not intact alginate, indicating that the CBM32 domain recognises alginate termini. The crystal structure containing both CBM32 and catalytic domains show that they do not interact with one another. The CBM32 domain contains a conserved Arg that may bind to the carboxyl group of alginate. The catalytic domain, meanwhile, shares a conserved substrate-binding groove, and the presence of two negatively charged Asp residues may dictate substrate specificity especially at subsite +1. As Persicobacter sp. CCB-QB2 was unable to utilise alginate, AlyQ may function to help the bacterium degrade cell walls more efficiently.
Considering the health benefits of tocotrienols, continuous works have been done on the encapsulation and delivery of these compounds. In this study, we encapsulated tocotrienols in chitosan-alginate microcapsules and evaluated their release profile. Generally, these tocotrienols microcapsules (TM) displayed high thermal stability. When subjected to pH adjustments (pH 1-9), we observed that the release of tocotrienols was the highest (33.78 ± 0.18%) under basic conditions. The TM were also unstable against the effect of ionic strength, with a high release (70.73 ± 0.04%) of tocotrienols even at a low sodium chloride concentration (50 mM). As for the individual isomers, δ-tocotrienol was the most sensitive to pH and ionic strength. In contrast, β-/γ-tocotrienols were the most ionic-stable isomers but more responsive toward thermal treatment. Simulated gastrointestinal model showed that the chitosan-alginate-based TM could be used to retain tocotrienols in the gastric and subsequently release them in the intestines for possible absorption.
Magnetic nanocellulose alginate hydrogel beads are produced from the assembly of alginate and magnetic nanocellulose (m-CNCs) as a potential drug delivery system. The m-CNCs were synthesized from cellulose nanocrystals (CNCs) that were isolated from rice husks (RH) by co-precipitation method and were incorporated into alginate-based hydrogel beads with the aim of enhancing mechanical strength and regulating drug release behavior. Ibuprofen was chosen as a model drug. The prepared CNCs, m-CNCs and the alginate hydrogel beads were characterized by various physicochemical techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM) and vibrating sample magnetometer studies (VSM). Besides the magnetic property, the presence of m-CNCs increased the integrity of the alginate hydrogel beads and the swelling percentage. The drug release study exhibited a controlled release profiles and based on the drug release data, the drug release mechanism was analyzed and discussed based on mathematical models such as Korsmeyer-Peppas and Peppas-Sahlin.
This study aimed to develop and characterize the calcium alginate films loaded with diclofenac sodium and other hydrophilic polymers with different degrees of cross-linking obtained by external gelation process. To the formed films different physicochemical evaluation were performed which showed an initial character of the films. The films produced by this external gelation process were found thicker (0.031-0.038 mm) and stronger (51.9-52.9 MPa) but less elastic (2.3%) than those non-cross-linked films (0.029 mm; 39.7 MPa; 4.4%). The lower water vapor permeability (WVP) values of the films were obtained where maximum level of crosslinking occurs. Composite films can be cross-linked in presence of external crosslinking agent to improve the quality of the produced matrices for various uses. The characterization of the film was performed using Differential Scanning Calorimetry (DSC) and Fourier-Transform Infrared Spectroscopy (FT-IR) analysis. The Scanning Electron Microscopy (SEM) study showed the morphology of treated composite films. The kinetic release studies showed a sustained release of the drug from the formulated films as it can be prolonged in composite film. The prepared biodegradable Ca-Alginate bio-composite film may be of clinical importance for its therapeutic benefit.
Maltooligosaccharides (MOSs) are emerging oligosaccharides in food-based applications and can be synthesized through the enzymatic synthesis of maltogenic amylase from Bacillus lehensis G1 (Mag1). However, the lack of enzyme stability makes this approach unrealistic for industrial applications. The formation of cross-linked enzyme aggregates (CLEAs) is a promising tool for improving enzyme stability, and the substrate accessibility problem of CLEA formation was overcome by the addition of porous agents to generate porous CLEAs (p-CLEAs). However, p-CLEAs exhibited high enzyme leaching and low solvent tolerance. To address these problems, p-CLEAs of Mag1 (Mag1-p-CLEAs) were entrapped in calcium alginate beads (CA). Mag1-p-CLEAs-CA prepared with 2.5% (w/v) sodium alginate and 0.6% (w/v) calcium chloride yielded 53.16% (17.0 U/mg) activity and showed a lower deactivation rate and longer half-life than those of entrapped free Mag1 (Mag1-CA) and entrapped non-porous Mag1-CLEAs (Mag1-CLEAs-CA). Moreover, Mag1-p-CLEAs-CA exhibited low enzyme leaching and high tolerance in various solvents compared to Mag1-p-CLEAs. A kinetic study revealed that Mag1-p-CLEAs-CA exhibited relatively high affinity towards beta-cyclodextrin (β-CD) (Km = 0.62 mM). MOSs (300 mg/g) were synthesized by Mag1-p-CLEAs-CA at 50 °C. Finally, the reusability of Mag1-p-CLEAs-CA makes them as a potential biocatalyst for the continuous synthesis of MOSs.
Aminoacylase I (E.C.3.5.1.14) was immobilized by entrapment in calcium alginate beads coated with polyethyleneimine for the production of L-phenylalanine by the hydrolysis of a racemic mixture of N-acetyl-DL-phenylalanine. The operational stability in terms of batch operation and continuous reaction in packed-bed bioreactor were studied. Kinetic constants, Km and Vmax values of free and immobilized enzymes were studied. Polyethyleneimine treatment was found to enhance the operational stability of the enzyme though its activity was substantially reduced. When polyethyleneimine-coated calcium alginate beads were packed into packed bed bioreactor, it was stable for at least 25 days under continuous operation without appreciable loss of activity.
The susceptibility of probiotics to low pH and high temperature has limited their use as nutraceuticals. In this study, enhanced protection of probiotics via microencapsulation was achieved. Lactobacillus plantarum LAB12 were immobilised within polymeric matrix comprised of alginate (Alg) with supplementation of cellulose derivatives (methylcellulose (MC), sodium carboxymethyl cellulose (NaCMC) or hydroxypropyl methylcellulose (HPMC)). L. plantarum LAB12 encapsulated in Alg-HPMC(1.0) and Alg-MC(1.0) elicited improved survivability (91%) in simulated gastric conditions and facilitated maximal release (∼100%) in simulated intestinal condition. Alg-HPMC(1.0) and Alg-MC(1.0) significantly reduced (P 7 log CFU g-1. Alg-MC and Alg-HPMC improved the survival of LAB12 against simulated gastric condition (9.24 and 9.55 log CFU g-1, respectively), temperature up to 90 °C (9.54 and 9.86 log CFU g-1, respectively) and 4-week of storage at 4 °C (8.61 and 9.23 log CFU g-1, respectively) with sustained release of probiotic in intestinal condition (>9 log CFU g-1). These findings strongly suggest the potential of cellulose derivatives supplemented Alg bead as protective micro-transport for probiotic strains. They can be safely incorporated into new functional food or nutraceutical products.
Obesity is a major epidemic that poses a worldwide threat to human health, as it is also associated with metabolic syndrome, type 2 diabetes and cardiovascular disease. Therapeutic intervention through weight loss drugs, accompanied by diet and exercise, is one of the options for the treatment and management of obesity. However, the only approved anti-obesity drug currently available in the market is orlistat, a synthetic inhibitor of pancreatic lipase. Other anti-obesity drugs are still being evaluated at different stages of clinical trials, while some have been withdrawn due to their severe adverse effects. Thus, there is a need to look for new anti-obesity agents, especially from biological sources. Marine algae, especially seaweeds are a promising source of anti-obesity agents. Four major bioactive compounds from seaweeds which have the potential as anti-obesity agents are fucoxanthin, alginates, fucoidans and phlorotannins. The anti-obesity effects of such compounds are due to several mechanisms, which include the inhibition of lipid absorption and metabolism (e.g., fucoxanthin and fucoidans), effect on satiety feeling (e.g., alginates), and inhibition of adipocyte differentiation (e.g., fucoxanthin). Further studies, especially testing bioactive compounds in long-term human trials are required before any new anti-obesity drugs based on algal products can be developed.