Medium and high substituted carboxymethyl starch: Synthesis, characterization and application

Citric acid cross-linked pomegranate peel extract-loaded pH-responsive β-cyclodextrin/carboxymethyl tapioca starch hydrogel film for diabetic wound healing

Pomegranate peel extract (PPE) hydrogel films filled with citric acid (CA) and β-cyclodextrin-carboxymethyl tapioca starch (CMS) were designed mainly to prevent wound infections and speed up the healing process. FTIR and NMR studies corroborated the carboxymethylation of neat tapioca starch (NS). CMS exhibited superior swelling behavior than NS. The amount of CA and β-CD controlled the physicochemical parameters of developed PPE/CA/β-CD/CMS films. Optimized film (OF) exhibited acceptable swellability, wound fluid absorptivity, water vapor transmission rate, water contact angle, and mechanical properties. Biodegradable, biocompatible, and antibacterial films exhibited pH dependence in the release of ellagic acid for up to 24 h. In mice model, PPE/CA/β-CD/CMS hydrogel film treatment showed promising wound healing effects, including increased collagen deposition, reduced inflammation, activation of the Wingless-related integration site (wnt) pathway leading to cell division, proliferation, and migration to the wound site. The expression of the WNT3A gene did not show any significant differences among all the studied groups. Developed PPE-loaded CA/β-CD/CMS film promoted wound healing by epithelialization, granulation tissue thickness, collagen deposition, and angiogenesis, hence could be recommended as a biodegradable and antibacterial hydrogel platform to improve the cell proliferation during the healing of diabetic wounds.

Effects of crosslinking agents on properties of starch-based intelligent labels for food freshness detection

The impact of citric acid, carboxymethyl cellulose, carboxymethyl starch, sodium trimetaphosphate, or soybean protein on the crosslinking of starch-based films was examined. These crosslinking starch films were then used to create pH-sensitive food labels using a casting method. Blueberry anthocyanins were incorporated into these smart labels as a pH-sensitive colorimetric sensor. The mechanical properties, moisture resistance, and pH responsiveness of these smart labels were then examined. Crosslinking improved the mechanical properties and pH sensitivity of the labels. These different crosslinking agents also affected the hydrophobicity of the labels to varying degrees. Soybean protein was the only additive that led to labels that could sustain their structural integrity after immersion in water for 12 h. Because it increased the hydrophobicity of the labels, which decreased their water vapor permeability, moisture content, swelling index, and water solubility by 47 %, 29 %, 52 % and 10 %, respectively. The potential of using these labels to monitor the freshness of chicken breast was then examined. Only the films containing soybean protein exhibited good pH sensitivity, high structural stability, and low pigment leakage. This combination of beneficial attributes suggests that the composite films containing starch and soybean protein may be most suitable for monitoring meat freshness.

Porous antimicrobial crosslinked film of hydroxypropyl methylcellulose/carboxymethyl starch incorporating gallic acid for wound dressing application

Because of weak mechanical qualities and low degree of swelling of hydroxypropyl methylcellulose/carboxymethyl starch (HP/CMS) blended films for wound dressing application, this work prepared a unique antimicrobial crosslinked film utilizing succinic acid (SA) as a non-toxic crosslinker and gallic acid (GAL) as an antibacterial agent. It was observed that the infrared-shifted peak position of OH stretching and bending in HP/CMS/SA/GAL films was caused by hydrogen bond formation among HP, CMS and GAL components. The antimicrobial crosslinked films considerably enhanced their mechanical properties and swelling degree. After adding SA and GAL, the films retained their porosity structure as observed by scanning electron images. Moreover, GAL-loaded HP/CMS/SA films could inhibit Staphylococcus aureus and Escherichia coli growth, showing their wound dressing potential. Crystallinity percentage, water vapor transmission rate, gel fraction, water solubility, water uptake and cytotoxicity were also investigated.

Removal of Pb (II) and Zn (II) in the mineral beneficiation wastewater by using cross-linked carboxymethyl starch-g-methacrylic acid as an effective flocculant

The cross-linked carboxymethyl starch-g-methacrylic acid (CCMS-g-MAA) was prepared by using grafting and micro-cross-linking in the one-pot preparation process. CCMS-g-MAA presented high removal capacity of Pb (II) of 57.13 mg/g at pH = 4 and high removal capacity of Zn (II) of 51.41 mg/g at pH = 5 by using a sample dosage of 0.68 g/L. Characterization results of FTIR, TG, and XRD illustrate that methacrylic acid and sodium tri-metaphosphate were successfully introduced into the structure of carboxymethyl starch. SEM characterization presented that the sample particles were amorphous aggregates with surface voids, which was favorable for the adsorption of heavy metal ions from wastewater. Adsorption isotherm results indicated that Freundlich equation could be better used to describe the adsorption process of metal ions on CCMS-g-MAA. The adsorption kinetic results indicated that the pseudo-second-order model is more suitable to describe this removal process. XPS results indicated that metal ions interacted with functional groups on the surface of flocculant, especially carboxyl groups. The removal process may be purposed that metal ions were adsorbed by porous material, and then combined with surface functional groups of the flocculant via electrostatic interaction, chelation or ion exchange. Subsequently, metal ions were separated from the wastewater with flocs precipitated in the bottom of solution via bridging and patching. The obtained results illustrated that CCMS-g-MAA was an effective material for the treatment of wastewater containing polymetallic ions besides mineral beneficiation wastewater supported by its excellent regeneration.

Temperature-sensitive multifunctional intelligent responsive hydrogel based on carboxymethyl agarose and N-isopropylacrylamide: Controlled drug release and accelerated wound healing

Wound healing remains challenging due to posttraumatic pain. At present, most wound dressings ignore the importance of wound pain. In this study, a temperature-sensitive multifunctional intelligent hydrogel patch (CPAG) containing lidocaine has developed for wound healing. CPAG hydrogel was prepared by grafting N-isopropylacrylamide and acrylamide onto carboxymethyl agarose (CMA) modified by agarose and encapsulating gallic acid and lidocaine. FTIR, 1H NMR spectroscopy, SEM and rheology were used to investigate its structure and temperature-sensitive properties. The contraction force generated by the temperature response characteristics of CPAG at 30 °C can accelerate wound healing. In vitro release assays demonstrated that CPAG directly controlled the same amount of lidocaine release at different temperatures through the competition between polymer-polymer and polymer-water interactions. In addition, MTT, H&E staining and stimulation test further proved its biological safety. The pain behavior study showed that the pain inhibition rates of the lidocaine cataplasms and LID@CPAG were 51.16 % and 67.83 %, respectively. In vitro and in vivo studies have shown that compared with the blank group, the bleeding volume of LID@CPAG decreased by 54.3 %, and the wound healing rate reached 97 %. CPAG hydrogel can play a comprehensive therapeutic role in accelerating wound closure by controlling drug release, analgesia, antioxidation and hemostasis.

Enhancement of the carboxymethylation of corn starch via induced electric field

This study aimed to enhance the synthesis of carboxymethyl starch (CMS) by induced electric field (IEF). Corn starch was alkalized, pumped into IEF system, and then reacted with monochloroacetic acid at excitation voltages of 0-400 V. IEF enhanced the carboxymethylation by accelerating the rate of OH- and ClCH2COO- attacking starch particles and slightly intensifying the thermal effect by ~7.1 °C (30 min). Compared with the control (0 V), IEF increased the degree of substitution and reaction efficiency by 0.056-0.148 and 9.37-24.56 %, caused more destruction in starch granular and crystal structure, and thus increased its water solubility, swelling power, and paste transparency. Furthermore, some new crystals were formed during IEF treatment, which enhanced the thermostability of CMS, showing an increase of the maximum decomposition temperature by 16-26 °C. Overall, the results classified that IEF could improve the carboxymethylation and enhance the thermostability of products, which provided guides for the applications of electro-techniques in starch modification involving charged species.

Carboxymethyl starch as a reducing and capping agent in the hydrothermal synthesis of selenium nanostructures for use with three-dimensional-printed hydrogel carriers

The hydrothermal method is a cost-effective and eco-friendly route for preparing various nanomaterials. It can use a capping agent, such as a polysaccharide, to govern and define the nanoparticle morphology. Elemental selenium nanostructures (spheres and rods) were synthesized and stabilized using a tailor-made carboxymethyl starch (CMS, degree of substitution = 0.3) under hydrothermal conditions. CMS is particularly convenient because it acts simultaneously as the capping and reducing agent, as verified by several analytical techniques, while the reaction relies entirely on green solvents. Furthermore, the effect of sodium selenite concentration, reaction time and temperature on the nanoparticle size, morphology, microstructure and chemical composition was investigated to identify the ideal synthesis conditions. A pilot experiment demonstrated the feasibility of implementing the synthesized nanoparticles into vat photopolymerization three-dimensional-printed hydrogel carriers based on 2-hydroxyethyl methacrylate (HEMA). When submersed into the water, the subsequent particle release was confirmed by dynamic light scattering (DLS), promising great potential for use in bio-three-dimensional printing and other biomedical applications.

Customizing Starch Properties: A Review of Starch Modifications and Their Applications

Starch has been a convenient, economically important polymer with substantial applications in the food and processing industry. However, native starches present restricted applications, which hinder their industrial usage. Therefore, modification of starch is carried out to augment the positive characteristics and eliminate the limitations of the native starches. Modifications of starch can result in generating novel polymers with numerous functional and value-added properties that suit the needs of the industry. Here, we summarize the possible starch modifications in planta and outside the plant system (physical, chemical, and enzymatic) and their corresponding applications. In addition, this review will highlight the implications of each starch property adjustment.

Green engineering of TMC-CMS nanoparticles decorated graphene sheets for targeting M. tuberculosis

Our current work intends to primarily engineer a new type of antibacterial composite by preparing a highly biocompatible graphene sheet decorated with TMC-CMS IPNs nanoparticles utilizing one-pot, green, cost-effective ultrasonication approach. The microstructure of as-formed materials was chemically confirmed using various analytical techniques such as ¹H-NMR, FTIR, UV/vis, SEM, and TEM. TEM data has proved the formation of uniformly distributed TCNPs on graphene surfaces with a small particle size of ~22 nm compared with that of pure nanoparticles (~30 nm). The inhibitory activity of these developed materials was examined against the growth of three different M. tuberculosis pathogens and in a comparison with the isoniazid drug as a standard anti-tuberculosis drug. The TCNPs@GRP composite attained MIC values of 0.98, 3.9, and 7.81 μg/mL for inhibiting the growth of sensitive, MDR, and XDR M. tuberculosis pathogens compared to the bare TCNPs (7.81, 31.25, >125 μg/mL) and the isoniazid drug (0.24, 0, 0 μg/mL), respectively. This reveals a considerable synergism in the antituberculosis activity between TCNPs and graphene nanosheets. Cytotoxicity of the TCNPs@GRP was examined against normal lung cell lines (WI38) and was found to have cell viability of 100% with the concentration range of 0.98-7.81 μg/mL.

Potential of Wood Hemicelluloses and Their Derivates as Food Ingredients

A holistic utilization of all lignocellulosic wood biomass, instead of the current approach of using only the cellulose fraction, is crucial for the efficient, ecological, and economical use of the forest resources. Use of wood constituents in the food and feed sector is a potential way of promoting the global economy. However, industrially established food products utilizing such components are still scarce, with the exception of cellulose derivatives. Hemicelluloses that include xylans and mannans are major constituents of wood. The wood hemicelluloses are structurally similar to hemicelluloses from crops, which are included in our diet, for example, as a part of dietary fibers. Hence, structurally similar wood hemicelluloses have the potential for similar uses. We review the current status and future potential of wood hemicelluloses as food ingredients. We include an inventory of the extraction routes of wood hemicelluloses, their physicochemical properties, and some of their gastrointestinal characteristics, and we also consider the regulatory route that research findings need to follow to be approved for food solutions, as well as the current status of the wood hemicellulose applications on that route.

Starch plasticization with choline dihydrogencitrate-based deep eutectic system

Two-component deep eutectic solvents (DES) based on choline dihydrogencitrate and glycerol or urea were tested as starch plasticizers. Thermal analysis techniques were applied to characterize the properties of starch/DES systems. The X-ray diffractometry measurements revealed a significant decrease in crystallinity indicating that used DES exhibited the ability to penetrate the ordered regions of potato starch, which is a necessary feature of a true plasticizer. However, the differential scanning calorimetry and dynamic thermal analysis results surprisingly showed an increase of Tg of starch materials indicating chemical crosslinking at elevated temperature. The eutectic solvents based on choline dihydrogencitrate could act as a plasticizer and a simultaneously crosslinking agent.

Curcumin-loaded HKUST-1@ carboxymethyl starch-based composites with moisture-responsive release properties and synergistic antibacterial effect for perishable fruits

The spoilage of fruit is one of the most important causes of fruit waste. High humidity by fresh fruit respiration leads to bacterial reproduction, which is the key factor of products corruption. Herein, a biological multifunctional film (Cur-HKUST-1@CMS/PVA) for fruits preservation with a high moisture environment was developed by cross-linking carboxymethyl starch (CMS)/polyvinyl alcohol (PVA) with MOF-199 (HKUST-1), and loaded with curcumin. The hydrophilic CMS facilitates water adsorption and moisture can stimulate curcumin release from HKUST-1. HKUST-1 not only acts as curcumin carriers but also forms synergistic antibacterial with curcumin to improve the antibacterial activity of the composites. XRD and SEM demonstrated that moisture disrupts the structure of HKUST-1 and releases curcumin and the results showed that the release of curcumin increased from 25.11 % to 58.32 % after moisture stimulation. In addition, Cur-HKUST-1@CMS/PVA had excellent antibacterial activity and antioxidant ability. As validation, the film can keep pitaya and avocado freshness at least 4 days longer than the control, confirming the effectiveness of Cur-HKUST-1@CMS/PVA in preventing fruit decay. Consequently, Cur-HKUST-1@CMS/PVA is a promising active packaging material for improve the shelf life of perishable fruits.

Nanoarchitectonics for Biodegradable Superabsorbent Based on Carboxymethyl Starch and Chitosan Cross-Linked with Vanillin

Due to the growing demand for sustainable hygiene products (that will exhibit biodegradability and compostability properties), the challenge of developing a superabsorbent polymer that absorbs significant amounts of liquid has been raised so that it can be used in the hygiene sector in the future. The work covers the study of the swelling and dehydration kinetics of hydrogels formed by grafting polymerization of carboxymethyl starch (CMS) and chitosan (Ch). Vanillin (Van) was used as the crosslinking agent. The swelling and dehydration kinetics of the polymers were measured in various solutes including deionized water buffers with pH from 1 to 12 and in aqueous solutions of sodium chloride at 298 and 311 K. The surface morphology and texture properties of the analyzed hydrogels were observed by scanning electron microscopy (SEM). The influence of this structure on swelling and dehydration is discussed. Fourier transform infrared (FTIR) analyses confirmed the interaction between the carboxymethyl starch carbonyl groups and the chitosan amino groups in the resulting hydrogels. Additionally, spectroscopic analyses confirmed the formation of acetal crosslink bridges including vanillin molecules. The chemical dynamics studies revealed that new hydrogel dehydration kinetics strongly depend on the vanillin content. The main significance of the study concerns the positive results of the survey for the new superabsorbent polymer material, coupling high fluid absorbance with biodegradability. The studies on biodegradability indicated that resulting materials show good environmental degradability characteristics and can be considered true biodegradable superabsorbent polymers.

Quantitative analysis of degree of substitution/molar substitution of etherified polysaccharide derivatives

Due to the unique properties such as nontoxicity, biodegradability, availability from renewable resources, and cost-effectiveness, polysaccharides play a very important part in the science and technology field. The various chemically modified derivatives of these offer a wide range of high value-added in both food and non-food industries. Among the chemical modification, etherified polysaccharide is one of the most widespread derivatives by introducing an ether group which is commonly stable in both acidic and alkaline conditions. Hydroxyalkylation, alkylation, carboxymethylation, cationization, and cyanoethylation are some of the modifications commonly employed to prepare polysaccharides ethers derivatives. There also has been a growing tendency for creating new types of modification by combining the different means of chemical techniques. The correct determination of degree of substitution (DS)/molar substitution (MS) is crucially important. The objective of this article is to summarize developments in synthetic etherified polysaccharides, involving analytical methods for determination of MS/DS, measurement processes, and the associated mechanisms.

Investigation of the vibrational density of states of sodium carboxymethyl starch glass via terahertz time-domain spectroscopy

We investigated the vibrational density of states of sodium carboxymethyl starch (CM-starch) by terahertz (THz) time-domain spectroscopy. The CM-starch showed a broad peak at ∼3 THz. The structure of the peak was similar to those corresponding to glucose-based polymer glasses possessing hydrogen bonds. The boson peak (BP) appeared at 1.16 THz at the lowest temperature and disappeared because of the existence of excess wing at higher temperatures. However, based on our novel BP frequency determination method using the inflection point of the extinction coefficient, the BP frequency showed almost no dependence on temperature. Further, the chain length dependence of the BP frequency of the glucose-based glasses showed that the BP frequency of the polymer glass was slightly lower than that of the monomer glass. The power law behaviour of the absorption coefficient suggested the existence of fractons, and the fractal dimension was estimated to be 2.33.

Morphology, Mechanical, and Water Barrier Properties of Carboxymethyl Rice Starch Films: Sodium Hydroxide Effect

Carboxymethyl rice starch films were prepared from carboxymethyl rice starch (CMSr) treated with sodium hydroxide (NaOH) at 10-50% w/v. The objective of this research was to determine the effect of NaOH concentrations on morphology, mechanical properties, and water barrier properties of the CMSr films. The degree of substitution (DS) and morphology of native rice starch and CMSr powders were examined. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and differential scanning calorimetry (DSC) were used to investigate the chemical structure, crystallinity, and thermal properties of the CMSr films. As the NaOH concentrations increased, the DS of CMSr powders increased, which affected the morphology of CMSr powders; a polyhedral shape of the native rice starch was deformed. In addition, the increase in NaOH concentrations of the synthesis of CMSr resulted in an increase in water solubility, elongation at break, and water vapor permeability (WVP) of CMSr films. On the other hand, the water contact angle, melting temperature, and the tensile strength of the CMSr films decreased with increasing NaOH concentrations. However, the tensile strength of the CMSr films was relatively low. Therefore, such a property needs to be improved and the application of the developed films should be investigated in the future work.

Preparation and characterization of starch-cellulose interpenetrating network hydrogels based on sequential Diels-Alder click reaction and photopolymerization

Herein, starch-cellulose interpenetrating network (IPN) hydrogels were fabricated by sequential Diels-Alder click reaction and photopolymerization in water. Moreover, β-cyclodextrin, a commonly used host molecule in supramolecular chemistry, was also introduced to improve the performance of the IPN hydrogel. Firstly, the starch-based dienes were synthesized by modifying starch with N-maleoyl-β-alanine, and the cellulose-based dienophiles were obtained by the reaction of cellulose and furfurylamide succinate; Secondly, the as-synthesized starch-based dienes, cellulose-based dienophiles, polymerizable β-cyclodextrin, crosslinker, and acrylamide were dissolved in water and obtained a transparent solution. The solution was maintained in a water bath of 50 °C for 3 h, forming the first network via catalyst-free click Diels-Alder reaction, subsequently, the second network was formed by photopolymerization. Their preparation conditions were optimized via one-factor experiments and their properties and structures were characterized. Finally, 5- fluorouracil (5-Fu) was used as a model drug to study the sustained release behavior of the drug-loaded hydrogels. Release profile was found to fit in Ritger-Peppas kinetic model and polymer relaxation and drug diffusion made a valuable contribution to drug release. Taking into account the virtues of easily controllable photopolymerization and catalyst-free Diels-Alder reaction, the strategy described here has a potential application in the preparation of IPN hydrogels.

Bioactive Carboxymethyl Starch-Based Hydrogels Decorated with CuO Nanoparticles: Antioxidant and Antimicrobial Properties and Accelerated Wound Healing In Vivo

In this study, nanocomposite hydrogels composed of sodium carboxymethylated starch (CMS)-containing CuO nanoparticles (CMS@CuO) were synthesized and used as experimental wound healing materials. The hydrogels were fabricated by a solution-casting technique using citric acid as a crosslinking agent. They were characterized by Fourier-transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and thermogravimetric analysis (TGA) to evaluate their physicochemical properties. In addition, swelling, antibacterial activities, antioxidant activities, cytotoxicity, and in vivo wound healing were investigated to evaluate the wound healing potential of the CMS@CuO nanocomposite hydrogels. Growth inhibition of the Gram-positive and Gram-negative pathogens, antioxidant activity, and swelling were observed in the CMS@CuO nanocomposite hydrogels containing 2 wt.% and 4 wt.% CuO nanoparticles. The hydrogel containing 2 wt.% CuO nanoparticles displayed low toxicity to human fibroblasts and exhibited good biocompatibility. Wounds created in rats and treated with the CMS@2%CuO nanocomposite hydrogel healed within 13 days, whereas wounds were still present when treated for the same time-period with CMS only. The impact of antibacterial and antioxidant activities on accelerating wound healing could be ascribed to the antibacterial and antioxidant activities of the nanocomposite hydrogel. Incorporation of CuO nanoparticles in the hydrogel improved its antibacterial properties, antioxidant activity, and degree of swelling. The present nanocomposite hydrogel has the potential to be used clinically as a novel wound healing material.

Synthesis of Carboxymethyl Starch-Bio-Based Epoxy Resin and their Impact on Mechanical Properties

In the current research, we observed numerous suggestions are promoting the use of bio-based epoxy resins, replacing the petroleum-based products like Diglycidyl ether of bisphenol A type epoxy resin DGEBA. With the passage of time, the impending challenges include preparation of environmentally-friendly epoxy with minimum toxic side effect and improved properties. Therefore, we describe a very useful method for preparing new silicone-bridged dimethyl siloxane monomers in high quantity, derived from naturally occurring eugenol. By putting the methyl siloxane, computed with different chain lengths into their molecular backbone. Such epoxy monomers have different molecular structure with high purity. This dimethyl siloxane epoxy, with lower viscosity than commercial DGEBA epoxy, has superior thermal properties, which were evaluated using differential scanning calorimetry DSC. Modification of CMS increases the hydrophilicity. Bio-based epoxy (self-prepared) resin improved adhesive properties, with the help of modified CMS. This study presents a very easy and effective chemical modification to enhance interfacial adhesion composites with superior properties.

Swelling of Hydrogels Based on Carboxymethylated Starch and Poly(Acrylic Acid): Nonlinear Rheological Approach

In this paper, the authors discuss the results of research on the preparation and properties of superabsorbent hydrogels based on carboxymethylated high-amylose corn starches. They were obtained by graft copolymerisation (in an aqueous environment) of acrylic acid and its sodium salt onto modified starches (with various substitution degrees DS = 0.2 and 0.8), using potassium persulfate as an initiator and N,N’-methylenebisacrylamide (MBA) as a cross-linker. Modified starches, with various DS, were used to synthesise two series of hydrogels with varying molar ratios of cross-linkers to monomers. The swelling behaviour of hydrogels was studied and their properties were estimated using the kinetic equation. The occurrence of starch–polyacrylic acid covalent interactions was demonstrated by FTIR analysis. Nonlinear rheological methods have proved to be very effective in assessing the mechanical properties of hydrogels. LAOS (large -amplitude oscillatory shear) analysis allowed the determination of the durability of the gel structure as a function of the amount of absorbed water.

Hydrophilic Films Based on Carboxymethylated Derivatives of Starch and Cellulose

The carboxymethylated derivatives of starch (CMS) and cellulose (CMC) were used for film preparation. The infrared spectroscopy revealed that crosslinking via ester bridges with citric acid occurred between the two polysaccharide derivatives. The effect of polysaccharide derivatives ratio on physicochemical properties of prepared films was evaluated. Generally, the values of tested parameters (moisture absorption, surface roughness, and mechanical and thermal properties) were between the values noted for neat CMS or CMC-based films. However, the physicochemical properties of the system with equal CMS/CMC weight ratio diverged from this trend, i.e., the highest tensile strength, the highest Young's modulus (ca. 3.4 MPa and ca. 4.9 MPa, respectively), with simultaneously the lowest moisture absorption (18.5% after 72 h) have been noted. Such systems could potentially find application in agriculture or pharmacy.

Cross-linked-substituted (esterified/etherified) starch derivatives as aqueous heavy metal ion adsorbent: a review

Starch is a biopolymer with outstanding economic and environmentally friendly attributes which has driven technological innovations to enhance its applications in food and non-food industries. Starch is constituted by O-H groups with valency and electronic characteristics that can initiate adsorption of aqueous heavy metal ions (AHMIs). However, this can be enhanced using various modification sequences. A common procedure is the cross-linking and substitution of the O-H groups via esterification and/or etherification reactions to produce starch derivative adsorbents (SDAs) with improved structural and functional properties for adsorption of AHMIs. The efficiency of SDAs developed using these procedures depends on the botanical source of the native starch base, porosity and structural stability of the derivative (i.e. degree of cross-linking), substituted functional group(s), degree of substitution and the steric/conformation effects of the substituted groups. Many works have been done to optimize these factors, and this review highlighted some of the tailored procedures and the results obtained.

A Spray-Dried, Co-Processed Rice Starch as a Multifunctional Excipient for Direct Compression

A new co-processed, rice starch-based excipient (CS) was developed via a spray-drying technique. Native rice starch (RS) was suspended in aqueous solutions of 10%–15% cross-linked carboxymethyl rice starch (CCMS) and 0.5%–6.75% silicon dioxide (in the form of sodium silicate), before spray drying. The resulting CSs were obtained as spherical agglomerates, with improved flowability. The compressibility study revealed an improved plastic deformation profile of RS, leading to better compaction and tensile strength. The presence of CCMS also ensured a rapid disintegration of the compressed tablets. CS-CCMS:SiO₂ (10:2.7), prepared with 10% CCMS, 2.7% silicon dioxide, and 40% solid content, was found to exhibit the best characteristics. Compared to the two commercial DC excipients, Prosolv^® and Tablettose^®, the flow property of CS-CCMS:SiO₂ (10:2.7) was not significantly different, while the tensile strength was 23%: lower than that of Prosolv^® but 4 times higher than that of Tablettose^® at 196 MPa compression force. The disintegration time of CS-CCMS:SiO₂ (10:2.7) tablet (28 s) was practically identical to that of Tablettose^® tablet (26 s) and far superior to that of Prosolv^® tablet (>30 min). These results show that CSs could potentially be employed as a multifunctional excipient for the manufacturing of commercial tablets by DC.

The production of gel beads of soybean hull polysaccharides loaded with soy isoflavone and their pH-dependent release

Core-shell hydrogel beads were successfully produced from soybean hull polysaccharides (SHP). Using electron microscopy, the beads were found to be spherical with smooth surfaces and have tight gel network internal structures. Fourier transform infrared spectroscopy, differential scanning calorimetry, and X-ray diffraction were used to investigate the interaction between soy isoflavone and SHP in the gel beads mesh-like structure. Furthermore, the encapsulation efficiency and loading capacity of gel beads for soy isoflavone are 66.90% and 4.67%, respectively, and have the ability of pH-responsive release in vitro. Through the mathematical model of kinetics, we found that the release of soy isoflavone from gel beads showed Fickian diffusion in release media (pH 2.0 and 7.4), but showed non-Fickian diffusion at pH 4.0 and 6.8. This polymer can be extended to prepare more versatile delivery and controlled release system, appealing for food, pharmaceutical, biomedicine and cosmetics applications.

Kinetics and Thermodynamics of Thermal Degradation of Different Starches and Estimation the OH Group and H2O Content on the Surface by TG/DTG-DTA

The main aim of this study is to estimate the kinetic and thermodynamic parameters of thermal decomposition of starches by the Coats-Redfern method. This procedure is a commonly used thermogravimetric analysis/difference thermal gravimetry/differental thermal analysis (TG/DTG-DTA) kinetic method for single rate form. The study also shows a proposed method for reactive hydroxyl groups content on the starch surface determination, and values were in range of 960.21-1078.76 mg OH per 1 g of starch. Thermal processing revealed the thermophysical properties of biomass for the kinetics of decomposition estimation. Activation energies reached the values in range of approximately 66.5-167 kJ·mol-1. This research also enables the determination of the temperature conditions required for becoming the desired form of material. Therefore, it is necessary to achieve the requested compact porous structure in an activation process, because in the native state, the polymer exhibits limited applications as a result of thermal decomposition, low shear stress, retrogradation, and syneresis, hence the low solubility in organic solvents. Thermodynamic parameters and reactive hydroxyl groups in this article review are innovative and have not yet been found in the literature.

Chemical Modification and Processing of Chitin for Sustainable Production of Biobased Electrolytes

In the present work we report on the development of a novel and sustainable electrolyte based on chitin. Chitin biopolymer was carboxymethylated in simple, mild, and green conditions in order to fine-tune the final properties of the electrolyte. To this end, chitin was modified for various reaction times, while the molar ratio of the reagents, e.g., sodium hydroxide and monochloroacetic acid, was maintained fixed. The resulting chitin derivatives were characterized using various techniques. Under optimized conditions, modified chitin derivatives exhibiting a distinct degree of carboxymethylation and acetylation were obtained. Structural features, morphology, and properties are discussed in relation to the chemical structure of the chitin derivatives. For electrolyte applications, the ionic conductivity increased by three magnitudes from 10⁻⁹ S·cm⁻¹ for unmodified chitin to 10⁻⁶ S·cm⁻¹ for modified chitin with the highest degree of acetylation. Interestingly, the chitin derivatives formed free-standing films with and without the addition of up to 60% of ionic liquid, the ionic conductivity of the obtained solid electrolyte system reaching the value of 10⁻³ S·cm⁻¹.

Hydrophilic films based on starch and carboxymethyl starch

The hydrophilic films based on starch and carboxymethyl starch (CMS) were obtained using cast method. The effect of CMS content on the physicochemical properties of prepared films were evaluated. With increasing content of starch derivative the moisture absorption, solubility in water as well as swelling ratio increased. The highest values of mechanical parameters (tensile strength and Young’s modulus) were determined for the starch/CMS film containing the lowest CMS amount, i.e. 10 wt.% (1.1 MPa, 15 MPa, respectively). For the same system the lowest moisture absorption, solubility in water as well as swelling ratio were reported. Thus, it could be concluded that for this system the highest crosslinking density has been achieved, what was confirmed by DMTA results. Such a film could potentially find application in food or agricultural industry.

Carboxymethylated starch and cellulose derivatives-based film as human skin equivalent for adhesive properties testing

The films based on carboxymethyl derivatives of starch (CMS) and cellulose (CMC) were proposed as a novel human skin equivalent. The physicochemical properties (moisture absorption, solubility in water, mechanical properties) of CMS/CMC films were evaluated. Additionally, some properties were compared to the human skin ones (surface roughness, tribology). The system based on CMS/CMC 25/75 wt. % was selected for testing the adhesive properties of pressure-sensitive adhesives commonly used for medical purposes (acrylic, silicone and polyisobutylene). Similar tests were performed for human skin. The peel adhesion values for CMS/CMC film and human skin were similar for all adhesives types tested. Applying such a skin equivalent allows to evaluate the functional properties of medical pressure-sensitive adhesives without the ethical and economic issues.

Ampholytic and Polyelectrolytic Starch as Matrices for Controlled Drug Delivery

The potential of the polyampholytic and polyelectrolytic starch compounds as excipients for drug controlled release was investigated using various tracers differing in terms of solubility and permeability. Ampholytic trimethylaminecarboxymethylstarch (TMACMS) simultaneously carrying trimethylaminehydroxypropyl (TMA) cationic groups and carboxymethyl (CM) anionic groups was obtained in one-step synthesis in aqueous media. Trimethylaminestarch (TMAS) and carboxymethylstarch (CMS) powders were also synthesized separately and then homogenized at equal proportions in liquid phase for co-processing by spray drying (SD) to obtain polyelectrolytic complexes TMAS-CMS (SD). Similarly, equal amounts of TMAS and CMS powders were dry mixed (DM) to obtain TMAS:CMS (DM). Monolithic tablets were obtained by direct compression of excipient/API mixes with 60% or 80% drug loads. The in vitro dissolution tests showed that ampholytic (TMACMS) and co-processed TMAS-CMS (SD) with selected tracers (one from each class of Biopharmaceutical Classification System (BCS)), were able to control the release even at very high loading (80%). The presence of opposite charges located at adequate distances may impact the polymeric chain organisation, their self-assembling, and implicitly the control of drug release. In conclusion, irrespective of preparation procedure, ampholytic and polyelectrolytic starch materials exhibited similar behaviours. Electrostatic interactions generated polymeric matrices conferring good mechanical features of tablets even at high drug loading.

Some Properties of Chemical Cross-Linking Biohydrogel from Starch and Chitosan

Chemical cross-linking was developed to prepare starch and chitosan-based hydrogels. First, the precursor of starch was synthesized through the reaction of carboxymethylation with sodium monochloroacetate, and then chitosan was grafted by using methacrylic acid as cross-linker. In this research, sago and cassava starches were used and mixed with chitosan, and the effect of methacrylic acid concentration was investigated to determine the grafting parameters and hydrogel characteristics. Compared to native starch and carboxymethylated starch, hydrogels from both starches have high ability to swell and high capacity to absorb water and oil. The highest grafting yield, grafting efficiency, and monomer conversion were achieved by experiment using 0.550 g of methacrylic acid per g of CMS-chitosan mixture. These hydrogels have a good potency as biodegradable absorbents for pharmaceutical and industrial application.

Preparation, optimization and swelling study of carboxymethyl sago starch (CMSS)-acid hydrogel

In this study, sago starch was modified in order to enhance its physicochemical properties. Carboxymethylation was used to introduce a carboxymethyl group into a starch compound. The carboxymethyl sago starch (CMSS) was used to prepare smart hydrogel by adding acetic acid into the CMSS powder as the crosslinking agent. The degree of substitution of the CMSS obtained was 0.6410. The optimization was based on the gel content and degree of swelling of the hydrogel. In this research, four parameters were studied in order to optimize the formation of CMSS–acid hydrogel. The parameters were; CMSS concentration, acetic acid concentration, reaction time and reaction temperature. From the data analyzed, 76.69% of optimum gel content was obtained with 33.77 g/g of degree of swelling. Other than that, the swelling properties of CMSS–acid hydrogel in different media such as salt solution, different pH of phosphate buffer saline solution as well as acidic and alkaline solution were also investigated. The results showed that the CMSS–acid hydrogel swelled in both alkaline and salt solution, while in acidic or low pH solution, it tended to shrink and deswell. The production of the hydrogel as a smart material offers a lot of auspicious benefits in the future especially related to swelling behaviour and properties of the hydrogel in different types of media.

Preparation of Activated Carbon from the Biodegradable film for Co2 Capture Applications

In this work for the fi rst time, activated carbons were prepared from carboxymethyl fi lm (low-cost carboxymethyl fi lm waste), using chemical activation with potassium hydroxide. The samples were characterized by nitrogen adsorption-desorption at 77 K, XRD, SEM methods. The high values of the specifi c surface area and total pore volume were achieved and were equal to 2064 m2/g and 1.188 cm3/g, respectively. Waste from the fi lm can be immediately utilized without CO2 production. This is the environmentally friendly way of waste utilization. Through this process, we can protect our environment. This study showed that the activated carbon obtained from carboxymethyl fi lm waste can be used as a good adsorbent for CO2 adsorption.

Effects of curing conditions on the structure of sodium carboxymethyl starch/mineral matrix system: FT-IR investigation

Strength properties of the microwave cured molding sands containing binders in a form of the aqueous solution of sodium carboxymethyl starch (CMS-Na) are higher than the same molding composition cured by conventional heating. Finding the reason of this effect was the main purpose in this study. Structural changes caused by both physical curing methods of molding sands systems containing mineral matrix (silica sand) and polymer water-soluble binder (CMS-Na) were compared. It was shown, by means of the FT-IR spectroscopic studies, that the activation of the polar groups in the polymer macromolecules structure as well as silanol groups on the mineral matrix surfaces was occurred in the microwave radiation. Binding process in microwave-cured samples was an effect of formation the hydrogen bonds network between hydroxyl and/or carbonyl groups present in polymer and silanol groups present in mineral matrix. FT-IR studies of structural changes in conventional and microwave cured samples confirm that participation of hydrogen bonds is greater after microwave curing than conventional heating.

Effect of microwave treatment on structure of binders based on sodium carboxymethyl starch: FT-IR, FT-Raman and XRD investigations

The paper deals with the influence of the microwave treatment on sodium carboxymethyl starch (CMS-Na) applied as a binder for moulding sands. The Fourier transformation infrared spectrometry (FT-IR), Raman spectroscopy (FT-Raman) and XRD analysis data of native potato starch and three different carboxymethyl starches (CMS-Na) with various degree of substitution (DS) before and after exposition to microwave radiation have been compared. FT-IR studies showed that polar groups present in CMS-Na structure take part in the formation of new hydrogen bonds network after water evaporation. However, these changes depend on DS value of the modified starch. The FT-Raman study confirmed that due to the impact on the samples by microwave, the changes of intensity in the characteristic bands associated with the crystalline regions in the sample were noticed. The X-ray diffraction data for microwave treated CMS-Na samples have been compared with the diffractograms of initial materials and analysis of XRD patterns confirmed that microwave-treated samples exhibit completely amorphous structure. Analysis of structural changes allows to state that the binding of sand grains in moulding sand with CMS-Na polymeric binder consists in the formation of hydrogen bonds networks (physical cross-linking).