Efficient heterogeneous synthesis of nucleophilic carboxymethyl hydrazides of polysaccharides.

Nucleophilic moieties in polysaccharides (PS) with distinct higher reactivity compared with the hydroxy group are interesting for sustainable applications in chemistry, medicine, and pharmacy. An efficient heterogeneous method for the formation of such nucleophilic PS is described. Employing alcohols as slurry medium, protonated carboxymethyl (CM) PS and hydrazine hydrate are allowed to react at elevated temperatures. The CM derivatives of starch and pullulan can be transformed almost quantitatively to the corresponding hydrazides. The reaction is less efficient for CM dextrans and CM xylans. As slurry media, 2-propanol and ethanol were probed, and the results are compared with a homogeneous procedure performed in water. Overall, the heterogeneous procedure is superior compared with the homogeneous route. 2-Propanol is the best slurry medium investigated yielding PS hydrazides with the highest nitrogen content.

Synthesis, characteristics, and applications of modified starch nanoparticles: A review.

Nowadays, starch nanoparticles (SNPs) are drawing attention to the scientific community due to their versatility and wide range of applications. Although several works have extensively addressed the SNP production routes, not much is discussed about the SNPs modification techniques, as well as the use of modified SNPs in typical and unconventional applications. Here, we focused on the SNP modification strategies and characteristics and performance of the resulting products, as well as their practical applications, while pointing out the main limitations and recommendations. We aim to guide researchers by identifying the next steps in this emerging line of research. SNPs esterification and oxidation are preferred chemical modifications, which result in changes in the functional groups. Moreover, additional polymers are incorporated into the SNP surface through copolymer grafting. Physical modification of starch has demonstrated similar changes in the functional groups without the need for toxic chemicals. Modified SNPs rendered differentiated properties, such as size, shape, crystallinity, hydrophobicity, and Zeta-potential. For multiple applications, tailoring the aforementioned properties is key to the performance of nanoparticle-based systems. However, the number of studies focusing on emerging applications is fairly limited, while their applications as drug delivery systems lack in vivo studies. The main challenges and prospects were discussed.

Valorization of unpopped Foxnut starch in stabilizing Pickering emulsion using OSA modification.

Starch was isolated from unpopped fox nut (Euryale ferox) and the effect of octenyl succinic anhydride (OSA) concentration (1, 2 and 3%) on physiochemical, functional, pasting, rheological and structural properties of was examined. The amylose content of native starch (22.9%) was higher than the modified starch (13.7%) for 3% OSA treatment. The water absorption capacity (1.29-0.9 g/g) significantly reduced, while oil absorption capacity (0.15-0.61 g/g), solubility (5-48%) and swelling power (2.77-13.60 g/g) increased after modification. The modification also altered the pasting properties by increasing the peak viscosity and reducing the pasting temperature. The cooked gel of all starch showed shear-thinning flow behavior and dynamic rheology confirmed reduction in storage and loss modulus after modification. Modified starch became rougher and irregular in shape and showed type A pattern as confirmed by SEM and XRD. Soybean oil-in-water Pickering emulsions were prepared by ultrasonication (US, 30 and 40% amplitude for 2 and 4 min) using starch as particle stabilizer and major factors influencing emulsion stability were investigated. Pickering emulsions prepared at 30 and 40% amplitude for 4 min US, produced the smaller droplet size, stable up to 15 days. However, all OSA modified starches were able to separate the oil and water even after the size of droplets increased with storage. The microstructure of the Pickering emulsions confirmed that starch particles aggregated in a tightly packed layer at the oil-water interface.

Association of antioxidant monophenolic compounds with ß-cyclodextrin-functionalized cellulose and starch substrates.

Polysaccharide substrates loaded with antioxidant and antimicrobial compounds, effectively protected by cyclodextrin moieties, can be a long-lasting solution to confer certain properties to fabrics, paper and other materials. ß-Cyclodextrin was attached to α-cellulose, bleached pulp and starch by a two-step esterification with a tetracarboxylic acid. The resulting derivatives were characterized by spectroscopy, thermal degradation analysis and capability of phenolphthalein inclusion. The carriers, containing between 89 and 171 µmol of ß-cyclodextrin per gram, were loaded with carvacrol, cuminaldehyde, cinnamaldehyde and hydroxytyrosol. From a stoichiometric addition, the percentage of compound retained ranged from 49% (hydroxytyrosol in pulp-cyclodextrin) to 92% (carvacrol in starch-cyclodextrin). Finally, the release rate to aqueous ethanol was measured over eight days and fitted to kinetic models. From the analysis of the mean dissolution time, it can be concluded that inserting ß-cyclodextrin units enhanced the long-term holding of phenolic active compounds in carbohydrate matrices.

Preparation and characterization of octenyl succinic anhydride modified waxy maize starch hydrolyzate/chitosan complexes with enhanced interfacial properties.

The preparation and characterization of colloidal complexes based on octenyl succinic anhydride starch hydrolyzate (OSAS) and chitosan (CS) were conducted. Results showed that OSA-S/CS ratio (r) and pH significantly affected complex turbidities and yields. The highest turbidity and yield were obtained at r = 6:1 when pH was fixed, and at pH 6.5 when r was fixed. All complexes remained liquid-like except that formed at pH 6.5, which exhibited a gel structure due to the strongest complexation. OSA-S/CS complexes had intertwined core-shell microstructure and exhibited electrostatic interactions between COO- and NH3+ groups of OSA-S and CS, respectively. The complexes prepared at r = 6:1 and pH 6.0 exhibited the most suitable wettability (θow = 91.97°) and interfacial adsorption dynamics. The compact lamellar network and intact cores of these complexes were also shown. This work provides profound and comprehensive information about the formation and physicochemical properties of OSA-S/CS complexes.

Structure and properties of corn starch synthesized by using sulfobetaine and deoxycholic acid.

Novel starch polymers (sulfobetaine-starch-deoxycholic acid) were first synthesized by grafting zwitterionic sulfobetaine and deoxycholic acid onto corn starch molecules. In order to explore the mechanism of modified starch, the chemical structure, morphological properties, thermal stability, and self-assembly performance of modified corn starch were determined. Preliminary structural characterization, using NMR, demonstrated that the glucose carbon C6 was the main etherification grafting site and C2 and C3 were the esterification grafting sites. This was confirmed using FT-IR to detect the presence of a new carbonyl signal around 1739 cm-1. XRD, SEM, and PLM micrographs showed structural losses in the starch granule. Thermogravimetric analysis showed an increase in thermal stability with etherification and esterification in nature. Self-assembly performance analysis demonstrated that the polymer formed more thermodynamically stable micelles under highly diluted conditions. This work will help expand the space for starch application.

Expression, Purification and Characterization of CAR/NCOA-1 Tethered Protein in E. coli Using Maltose-Binding Protein Fusion Tag and Gelatinized Corn Starch.

The constitutive active/androstane receptor (CAR) is a nuclear receptor that functions as a xenobiotic sensor, which regulates the expression of enzymes involved in drug metabolism and of efflux transporters. Evaluation of the binding properties between CAR and a drug was assumed to facilitate the prediction of drug-drug interaction, thereby contributing to drug discovery. The purpose of this study is to construct a system for the rapid evaluation of interactions between CAR and drugs. We prepared recombinant CAR protein using the Escherichia coli expression system. Since isolated CAR protein is known to be unstable, we designed a fusion protein with the CAR binding sequence of the nuclear receptor coactivator 1 (NCOA1), which was expressed as a fusion protein with maltose binding protein (MBP), and purified it by several chromatography steps. The thus-obtained CAR/NCOA1 tethered protein (CAR-NCOA1) was used to evaluate the interactions of CAR with agonists and inverse agonists by a thermal denaturation experiment using differential scanning fluorometry (DSF) in the presence and absence of drugs. An increase in the melting temperature was observed with the addition of the drugs, confirming the direct interaction between them and CAR. DSF is easy to set up and compatible with multiwell plate devices (such as 96-well plates). The use of DSF and the CAR-NCOA1 fusion protein together allows for the rapid evaluation of the interaction between a drug and CAR, and is thereby considered to be useful in drug discovery.

Dual modification of various starches: Synthesis, properties and applications.

The problems associated with native starches (NSs) and single modified starches were stated in order to justify dual modification of various starches. Broadly, there are two types of dual modification, i.e., homogeneous dual modification and heterogeneous dual modification. The combination of two physical modifications, e.g., (extrusion/annealing); two chemical modifications, e.g., (succinylation/cross-linking) and two enzymes modification (α-amylase/pullulanase) falls under the former classification and the latter classification is the combination of two of each of the differently stated modifications, e.g., acetylation/annealing, extrusion/succinylation, and microwave-assisted phosphorylation, etc. The classification, synthesis, properties and applications of dually modified starches were discussed. There is an attempt to elucidate the problems of each of the single modification in order to justify dual modifications. In dual modifications, the order of reactions, the reaction conditions, the medium of reaction, and the botanical sources of the various starches are very important parameters.

Bio-Based Thermoplastic Starch Composites Reinforced by Dialdehyde Lignocellulose.

In order to improve the mechanical properties and water resistance of thermoplastic starch (TPS), a novel reinforcement of dialdehyde lignocellulose (DLC) was prepared via the oxidation of lignocellulose (LC) using sodium periodate. Then, the DLC-reinforced TPS composites were prepared by an extrusion and injection process using glycerol as a plasticizer. The DLC and LC were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and the effects of DLC content on the properties of the DLC/TPS composites were investigated via the evaluation of SEM images, mechanical properties, thermal stability, and contact angles. XRD showed that the crystallinity of the DLC decreased due to oxidation damage to the LC. SEM showed good dispersion of the DLC in the continuous TPS phase at low amounts of DLC, which related to good mechanical properties. The tensile strength of the DLC/TPS composite reached a maximum at a DLC content of 3 wt.%, while the elongation at break of the DLC/TPS composites increased with increasing DLC content. The DLC/TPS composites had better thermal stability than the neat TPS. As the DLC content increased, the water resistance first increased, then decreased. The highest tensile strength and elongation at break reached 5.26 MPa and 111.25%, respectively, and the highest contact angle was about 90.7°.

Synthesis and characterization of starch nanocellulosic films incorporated with Eucalyptus globulus leaf extract.

Carrot cellulose nano fibers (CNF) have been extracted from carrot pulp using acid hydrolysis process. The size of the CNF was in the range of 6.33-58.77 nm. Starch nano-composite films were manufactured using varying concentration of CNF (5%, 10%, 15%, 20%) and mechanical properties of the films were studied at relative humidity 50% and 75%. Nano-composite films were manufactured using Eucalyptus globulus leafs extract (1%, 2%, 3%, 4%). Physio-chemical properties, antioxidant, antimicrobial, morphological and crystalline properties of the films were studied. Nano-composite films with 4% Eucalyptus globulus leafs extract was best to provide better barrier, antioxidant properties to grapes when wrapped and stored at room temperature (25 ± 2)°C for 7 days and refrigerator temperature (4 ± 1)°C for 28 days. Wrapped grapes with NCC/Eucalyptus globulus leaf extract stored for 28 days either at 25 °C or 4 °C had bacterial surface loads reduced up to 5 orders of magnitude compared to non-wrapped samples and had 4 orders of magnitude less bacterial surface loads than at the beginning of the experiments. Wrapped grapes with NCC/Eucalyptus globulus leaf extract significantly reduced the growth of Escherichia coli, Listeria monocytogenes, Salmonella typhimurium and Penicillium spp. when the cells of these organisms were spiked onto grapes and the samples were stored either at (25 ± 2) °C or (4 ± 1) °C for 28 days. The results showed that nano-composite with 4% Eucalyptus globulus leafs extract films have immense potential as food packaging/wrapping material.

Octenyl-succinylated inulin for the encapsulation and release of hydrophobic compounds.

Octenyl-succinylated inulins (OSA-inulin) were synthesized in aqueous solutions using inulin with varying degrees of polymerization (DP). They were characterized using 1H NMR and FTIR and their degrees of substitution were determined. All the samples formed micellar aggregates in aqueous solution above a critical aggregation concentration (CAC) and solubilized beta-carotene. The amount of beta carotene solubilized within the micelles ranged from 12 to 25 mg/g of OSA-inulin and depended on the inulin molar mass. Dynamic light scattering showed that the aggregates, with and without dissolved beta-carotene, were ∼10-15 nm in size and this was confirmed by Transmission Electron Microscopy which also indicated that the micelles had a globular shape. OSA-inulin particles containing encapsulated beta-carotene were produced by freeze-drying. The encapsulated beta-carotene was not released from the freeze-dried particles when introduced into simulated gastric fluid at pH 2.5 but was readily released in simulated small intestinal fluid at pH 7. The results demonstrate the potential application of OSA-inulin in the encapsulation, dissolution and targeted delivery of hydrophobic drug molecules for nutraceutical, pharmaceutical and medical applications.

Effect of processing methods on xylitol-starch base co-processed adjuvant for orally disintegrating tablet application.

Orally disintegrating tablet (ODT) is a friendly dosage form that requires no access to water and serves as a solution to non-compliance. There are many co-processed adjuvants available in the market. However, there is no single product possesses all the ideal characteristics such as good compressibility, fast disintegration and good palatability for ODT application. The aim of this research was to produce a xylitol-starch base co-processed adjuvant which is suitable for ODT application. Two processing methods namely wet granulation and freeze drying were used to compare the characteristics of co-processed adjuvant comprising of xylitol, starch and crospovidone XL-10 mixed at various ratios. The co-processed excipients were compressed into ODT and physically characterized for powder flow, particle size, hardness, thickness, weight, friability, in-vitro disintegration time and in-situ disintegration time, lubricant sensitivity, dilution potential, Fourier transform infrared spectroscopy, scanning electronic microscopy and x-ray diffraction analysis. Formulation F6 was selected as the optimum formulation due to the fastest in-vitro (135.33±11.52 s) and in-situ disintegration time (88.67±13.56s) among all the formulations (p<0.05). Increase in starch component decreases disintegration time of ODT. The powder flow fell under the category of fair flow. Generally, it was observed that freeze drying method produced smaller particle size granules compared to wet granulation method. ODT produced from freeze drying method had shorter disintegration time compared to ODT from wet granulation batch. In conclusion, a novel co-processed excipient comprised of xylitol, starch and crospovidone XL-10, produced using freeze drying method with fast disintegration time, good compressibility and palatability was developed and characterized. The co-processed excipient is suitable for ODT application.

In-vitro and in-vivo evaluation of modified sodium starch glycolate for exploring its haemostatic potential.

The control of blood flow from breached blood vessels during surgery or trauma is challenging. With the existing treatment options being either expensive or ineffective, the development of a haemostat that overcome such drawbacks would be beneficial. With an aim to develop an ideal haemostat, the potential of sodium starch glycolate (SSG), a commonly used pharmaceutical disintegrant was modified to obtain porous microparticles (pSSG). The biodegradability, cyto-compatibility and haemo-compatibility of the modified particles were confirmed using appropriate studies. In comparison to starch and SSG, the irregular shaped pSSG demonstrated spontaneous and significant fluid absorption (3500+500 %) and formed a physical barrier to blood flow. In addition, significant blood cells aggregation and platelet activation was observed in the modified micoparticles leading to rapid clot formation. In-vivo studies on liver and abdominal artery injury models in rats indicated the superior haemostatic potential of pSSG over SSG and starch. The results indicated that pSSG can be explored further in clinical evaluation as a hemostat.

Rapid and solvent-free synthesis of pH-responsive graft-copolymers based on wheat starch and their properties as potential ammonium sorbents.

A rapid and cost-effective reactive extrusion (REx) method was employed in this study as an alternative technique for the graft-copolymerization of non-food grade native wheat starch with acrylamide, and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) monomers, with a total starch/monomer ratio of 3:1, using twin-screw extrusion technology. The influence of AMPS content ratio on the REx process was monitored using specific mechanical energy, die pressure and torque values recorded during the extrusion. The as-prepared starch-copolymers were characterized using ATR-FTIR, NMR, TG-DSC, and elemental analysis. An average grafting efficiency and monomer conversion of ~61 and ~86%, respectively, was achieved within 5 min of extrusion at a high starch concentration (0.75:1 w/w starch-water). The copolymer with starch/acrylamide/AMPS weight ratio of 75:20:4 showed the highest swelling capacity in water, while behaving similarly to polyelectrolyte networks in the presence of free ions in both NaCl and NH4Cl solutions. A steady NH4+ adsorption capacity was also recorded for these starch-copolymers within the pH range of ~5.5-8.5, which exceeded those of the natural sorbents. These findings indicate the suitability of the starch-copolymers as potential precursors of effective sorbents, thus confirming the feasibility of using REx to produce pH-responsive hybrid copolymers based on wheat starch at low-cost.

Octenylsuccinylation differentially modifies the physicochemical properties and digestibility of small granule starches.

The impact of starch granule size on 2-octenyl-1-succinic anhydride (OSA) modification remains unclear. To investigate changes of structural, physicochemical, digestibility and emulsifying properties due to OSA modification, five small granule starches (from wheat, rice, oat, quinoa and amaranth) were selected and compared with a standard large granule starch (waxy maize). OSA starches were prepared in 3% (volume by weight) OSA reagent with continuous stirring for 6 h under constant pH of 8.5. The hypothesis was that property changes induced by OSA treatment can be more efficiently achieved in small granule starches (< 10 µm diameter). Small granule OSA starches generally had greater emulsion stability, swelling power and digestibility after gelatinization than waxy maize OSA starch, likely due to the unique physical properties and specific molecular structures of small granule starches, i.e. low sedimentation coefficient, low DP of amylopectin and highly branched amylopectin with short chain length. Granule sizes of OSA starches significantly impact on swelling power, amylose leaching, digestibility and emulsifying capacity, but to different extents depending on botanical origin.

Synthesis and properties of thermoplastic starch laurates.

Maize starch was allowed to react homogeneously in N,N-dimethylacetamide (DMAc)/LiCl with lauric acid activated with 4-toluenesulfonyl chloride, N,N'-dicyclohexylcarbodiimide/4-(1-pyrrolidinyl)pyridine, 1,1'-carbonyldiimidazole, and N,N-dimethylformamide (DMF) combined with oxalyl chloride. Characterization of the products by means of 13C NMR spectroscopy revealed different substitution patterns depending on the activation agent. The activation of lauric acid with DMF in combination with oxalyl chloride gave starch laurates of highest degree of substitution (DS), yield and reaction efficiency. The melting temperatures and the solubility of the thermoplastic starch laurates were found to depend on the DS, the substitution pattern, and on the molar mass of the starch esters.

New strategies for the construction of eggshell powder reinforced starch based fire hazard suppression biomaterials with tailorable thermal, mechanical and oxygen barrier properties.

A novel eco-friendly approach is highlighted for synthesizing chicken eggshell powder (EP) modified starch-g-poly(N-isopropylacrylamide) (starch-g-PNIPAAm) bionanocomposites (BNCs) by emulsifier-free emulsion polymerisation and aiming to study the effect of EP on the properties of modified starch BNCs. Young's modulus and tensile strength of BNCs are found to be improved dramatically. The enhanced char forming ability of EP improves the thermal stability of BNCs at high temperature as investigated by thermogravimetric analyses carried out in inert atmosphere. The cone calorimeter test revealed that the 4% w/v EP-based BNC resulted suppression on fire hazards in terms of reduction in PHRR (decreased by 33.3%), PSPR (decreased by 75.3%) compared with those of the control starch-g-PNIPAAm and could be attributed to the insulating barrier effect of EP. In addition, the fire retardancy of the BNCs is investigated from limiting oxygen index (LOI) test. The surface morphology and the elemental content of the collected char residues of BNCs after fire retardant test is analysed by FESEM and EDX. Further the oxygen barrier property of BNC with 4% w/v EP is reduced by 73% compared to starch-g-PNIPAAm. The resulting nanostructure and molecular interactions in the BNCs are analysed by FTIR, XRD and TEM.

One-step synthesis of eco-friendly boiled rice starch blended polyvinyl alcohol bionanocomposite films decorated with in situ generated silver nanoparticles for food packaging purpose.

The study reports a one-step preparation of polyvinyl alcohol/boiled rice starch blend film fabricated with in situ generated silver nanoparticles (PVA/BRS/sAgNPs) formed in the presence of sunlight irradiation. The bionanocomposite appeared to have dark brown color with a characteristic surface plasmon resonance peak at 439 nm. Further characterization has confirmed the presence of physical interactions among the components PVA, BRS and sAgNPs. Compared to the control PVA, the nanocomposites showed improved mechanical and optical properties with decreased water sensitivity. Presence of boiled rice starch and sAgNPs were also found to influence the light transmittance of composite film. Moreover, PVA/BRS/sAgNPs film was found to have superior barrier property against environmental microorganisms. Biodegradation of the composite films was studied by indoor soil burial test and was assessed by visual appearance, weight loss and FTIR analysis. Interestingly, both the PVA/BRS and PVA/BRS/sAgNPs films proved to be biodegradable and hence have promising application as cost effective food packaging material with the latter having marked antimicrobial property.

Grafting from Starch Nanoparticles with Synthetic Polymers via Nitroxide-Mediated Polymerization.

Nitroxide-mediated polymerization (NMP) is employed to graft synthetic polymers from polysaccharides. This work demonstrates the first successful polymer grafting from starch nanoparticles (SNPs) via NMP. To graft synthetic polymers from the SNPs' surface, the SNPs are first functionalized with 4-vinylbenzyl chloride prior to reaction with BlocBuilder MA yielding a macroinitiator. Methyl methacrylate with styrene, acrylic acid, or methyl acrylate are then grafted from the SNPs. The polymerizations exhibited linear reaction kinetics, indicating that they are well controlled. Thermal gravimetric analysis and spectroscopic techniques confirmed the synthesis of the precursors materials and the success of the grafting from polymerizations. The incorporation of hydrophobic synthetic polymers on hydrophilic SNPs yields new hybrid materials that could find use in several industrial applications including paper coatings, adhesives, and paints.

Synthesis and characterization of a low solubility edible film based on native cassava starch.

Films based on cassava starch have been widely used for fruit coating; however, it is necessary to incorporate other polymers in order to improve mechanical properties, once starch only leads to highly hydrophilic films, compromising their application. In this way, a polymeric blend based on cassava starch, chitosan and gelatin was combined with a plasticizer to produce biodegradable films with satisfactory mechanical and barrier properties, in order to be used as fruit coating. The films were prepared by casting method and a statistical design of 23 was used to evaluate the effect of each polymer and what their combinations would influence over the final product. The formation of a physical blend was confirmed by FTIR. It showed low solubility, varying (10 ±â€¯2) % a (23 ±â€¯4) %, Opacity ranging from (1.06 ±â€¯0.04) to (1.55 ±â€¯0.13) AU x nm/mm, thickness from (0.20 ±â€¯0.01) mm to (0.44 ±â€¯0.03) mm and water vapor transmission rate ranging from 25 ±â€¯0.2 to 30 ±â€¯1.4 g s-1 m-2. Lower amounts of starch led to more flexible, less opaque and soluble films, while the combination of higher levels of starch and chitosan was responsible for lowering films water vapor transmission rate. Thus, the films showed interesting properties for fruit surface coating.