High Degree Of Substitution Research Articles

The degree of substitution of OSA-modified starch affects the retention and release of encapsulated mint flavour

This study explored the effect of the degree of substitution (DS) of octenyl succinic anhydride (OSA)-modified starch on the retention and release properties of spray-dried mint flavour microcapsules. The results showed that a higher DS (0.0287, 0.0379) led to greater flavour retention (86.68 %, 90.10 %). The flavour release was negatively correlated with DS during simulated oral processing. A mechanism by which DS affects flavour release was proposed. The emulsifying capacity was improved with increasing DS, thus forming an effective interface. The effective interface increased the partition coefficient, thereby reducing the release. During oral processing, a lower friction coefficient and higher microstructural stability and carrier enzymatic resistance jointly promoted interface stabilization. Data obtained using the EPI suite, a gas chromatograph, a mini traction machine, a Mastersizer analyser and confocal scanning laser microscopy validated this mechanism. This study provides a strategy for designing flavour microcapsules with high retention and slow-release properties using OSA-modified starch.

Tailored sequencing of highly brominated Poly(ether ether ketone) as a means to preserve crystallizability and enhance Tg

In this report, the bromination of poly(ether ether ketone) (PEEK) using the mild reagent N-bromosuccinimide (NBS) is explored to generate controlled random and blocky microstructures. Bromination proceeded quantitatively in both the solution state and semicrystalline gel-state, and degrees of bromination between 25 and 175 mol% were obtained for both random and blocky BrPEEK. Spectroscopic evidence revealed a higher prevalence of unfunctionalized repeat units for blocky BrPEEK than random BrPEEK at similar degrees of functionality. Furthermore, at similar degrees of bromination, blocky BrPEEK exhibited enhanced glass transition temperatures, greater crystallizability, higher melting temperatures, and faster crystallization kinetics than random BrPEEK, suggesting longer segments of unfunctionalized PEEK in blocky BrPEEK. Overall, this work demonstrates that PEEK can be brominated to very high degrees of substitution in the semicrystalline gel-state while preserving crystallizability and effectively blocking up the functionality.

Cellulose allylcarbamate with high content of reactive double bonds for thiol-ene reaction

Polysaccharide phenylcarbonates react with amines to form carbamates with high efficiency and can be used to introduce reactive CC bonds into a biopolymer, which may be converted by thiol-ene click reactions. Thus, cellulose phenylcarbonates are allowed react with allylamine by nucleophilic reaction to yield cellulose allylcarbamate of very high degree of substitution (DS). The DS of allylcarbamate moieties could be controlled by the molar ratio of allylamine to phenylcarbonate groups. Pure products without remaining phenylcarbonate substituents were accessible. The allylcarbamate moieties are reactive regarding the radical thiol-ene reaction that was exemplified by the reaction of cellulose allylcarbamate with 2-(diethylamino)ethane-1-thiol hydrochloride (DEAET) in dimethyl sulfoxide using a photoinitiator under mild conditions. The phenylcarbonates- and allylcarbamates of cellulose as well as the DAEAET adduct were characterized by elemental analysis, NMR- and FTIR spectroscopy.

Guar gum propionate-kojic acid films for Escherichia coli biofilm disruption and simultaneous inhibition of planktonic growth

Nosocomial bacterial infections associated with biofilms inspire to explore newer bactericidal strategy with eco-friendly biomaterials as sustainable alternatives. In this research work, we successfully developed bio-safe films from kojic acid(KA) and guar gum propionate(GGP) for Escherichia coli biofilm disruption and planktonic cell killing. High DS(degree of substitution = 1.52) GGP was synthesized from guar gum (GG)assisted by chaotropic ions at room-temperature. Biopolymers were routinely characterized in CHN analyzer, FT-IR, TGA and XRD analysis. KA loaded GGP films were prepared by cross-linking the molecules in presence of epichlorhydrin and two different percentages of KA were employed. Film physical and tensile properties were systematically evaluated and optimized. Water vapour permeability (WVP) and tensile strength of final film GGPFK10 were recorded at 0.741 ± 0.09gmm−1kPa−1h−1 and 19.23 MPa. KA release from GGP matrix followed controlled diffusion process. MIC of GGP was 130 μg/mL and zone of inhibition of GGPFK10 was confirmed at 16.1 mm. SEM experiments disclosed the absence of pili-like structures with squeezed and elongated cellular morphology in dead planktonic cells. Disruption of biofilms was experimented in detail by CV assay, fluorescent, light microscopic and SEM studies. The film showed excellent cell-viability on human adult dermal fibroblast (HADF)cell-line. Overall, the biosafe film would be a potent antibacterial device for treating infections against E.coli biofilms and planktonic cells.

Green synthesis of carboxymethyl cellulose from agricultural waste its characterization

In the present study, corncob (an agricultural waste) has been explored as a source of cellulose. Cellulose was extracted from corncob through removal of hemicellulose and lignin. The carboxymethyl cellulose (CMC) was then synthesized from extracted cellulose by alkalization and etherification with 30% NaOH and 120% monochloro acetic acid (MCA) in ethanol medium respectively. Characterization of prepared CMC was carried out by various techniques like Fourier Transform Infra-Red (FTIR) spectroscopy, X-Ray Diffraction (XRD) and Scanning Electron Microscpoe (SEM). Back titration method was used to determine the Degree of Substitution (DS). The synthesized CMC obtained has a large DS value of 2.27. The purity of CMC was high at 91.65% and showed a yield of 1.20g/g, intrinsic viscosity of 1.02, water holding capacity 3.81g/g and oil holding capacity 1.66g/g. Higher degree of substitution is achieved in this work. The synthesized product is effective suitable additive for food and various pharmaceuticals industries.

Complexation behavior of carboxymethyl short-chain amylose and quaternized chitosan

The complexation of carboxymethyl short-chain amylose (CSA) and hydroxypropyl trimethyl ammonium chloride chitosan (HACC) and the stability of CSA/HACC nanocomplex were investigated. Resonance light scattering (RLS), turbidity, nanoparticle size and zeta potential analyses revealed that the complex coacervation occurred between CSA and HACC. The mass ratio and pH markedly influenced the complexation behavior; CSA with a higher degree of substitution (DS0.2) altered the complexation at a lower mass ratio and pH, increasing the turbidity and RLS intensity. The results of particle size and zeta potential analyses indicated that CSA/HACC complexes possessed the good pH and ionic strength stability. In addition to electrostatic interactions, hydrogen bonding and hydrophobic effects were also determined to be involved in the complexation process using thermal titration calorimetry (ITC). Additionally, the process was spontaneous, and CSA with a higher DS showed stronger complexation ability. These results may enable the understanding of polysaccharide complex behaviors.

Carboxymethylation modification, characterization, antioxidant activity and anti-UVC ability of Sargassum fusiforme polysaccharide

Taking the degree of substitution (DS) as the index, the carboxymethylation conditions of Sargassum fusiforme polysaccharide (SFP) were studied. According to the single factor experiment results, the optimum experimental conditions were obtained: sodium hydroxide concentration, 15% (20 mL); alkalization temperature, 50 °C; dosage of chloroacetic acid 1.5 g; etherification time, 2 h, and the Carboxymethyl Sargassum fusiforme polysaccharide (CSFP) with the highest DS (0.635) was obtained. And then, the physicochemical properties, structural information and bioactivity of SFP and CSFP were characterized. The SFP and CSFP were composed of four monosaccharides, with a small amount of protein, and their molecular weights to 780.2 kDa and 386.3 kDa respectively. The results of FTIR and NMR showed that the carboxymethyl was successfully grafted onto the C-4 and C-6 of sugar chain. The results of anti UVC experiment showed that SFP and CSFP had a certain negative effect on cell activity, and the degree of damage caused by UVC radiation was weakened, and the anti UVC performance of CSFP was better than that of SFP.

Encapsulation of indole-3-carbinol in Pickering emulsions stabilized by OSA-modified high amylose corn starch: Preparation, characterization and storage stability properties

The stability of hydrophobic bioactive compound indole-3-carbinol (I3C) is a challenge for application. In this work, Pickering emulsions were prepared to encapsulate I3C. As the emulsifier, high amylose corn starch was pretreated by acid hydrolysis, afterwards modified by different concentrations of octenyl succinic anhydride (OSA), and their emulsions were evaluated. The XRD, SEM and FTIR results indicated the successful modification. ζ-potential, mean droplet size and emulsification index (EI) of the emulsions confirmed that modified starch with a higher degree of substitution (DS) was more effective for enhancing the storage stability. The results of encapsulation efficiency (EE) and retention degree of I3C after 14 d also proved the assumption. Moreover, the Pickering emulsions protected I3C against ultraviolet light and achieved controlled release in vitro. The food-grade Pickering emulsion loading I3C is promising to be used as a nutrient or dietary supplement for food applications.

Preparation and Characterization of Thermoplastics Achira (Canna indica L.) Starch by Three Succination Methods

AbstractThermoplastic starches (TPS) from achira, succinated to 3% and 5% octenyl succinate anhydrous (OSA) using aqueous medium, reactive extrusion (REX), and in situ are developed (TPS 3A, TPS 5A, TPS 3R, TPS 5R, TPS 3I, and TPS I5). The physicochemical properties are studied to explore the effect of different methods applied to modified thermoplastic starches. Analysis of infrared spectroscopy and nuclear magnetic resonance of proton shows that the methods used in succination are effective in esterifying starches. REX and the in situ method make it possible to obtain materials with higher degree of substitution (DS), from 0.011 to 0.050, affecting thermoplasticization. The aqueous method promotes greater thermal stability, TPS 3A and TPS 5A are degraded at temperature ranges from 135 to 279 °C and shows a pattern similar to counterpart native TPS 0 (sample control), unlike the REX and the in situ method, both of them beginning degrading at lower temperature values than all starches. Mechanical properties and contact angle are influenced by the processing method and not by DS or glycerol content. All achira TPS developed are a feasible alternative for application in the industry dedicated to the processing of bioplastics.

In Situ Reduced Graphene Oxide and Polyvinyl Alcohol Nanocomposites With Enhanced Multiple Properties.

The nanocomposites formed by graphene oxide (GO) and carbazate-modified polyvinyl alcohol (PVA-N) were developed to investigate their multiple properties for wide applications. Their physicochemical characterizations confirmed that the in situ reduced GO (rGO) not only decreased the crystallization but also induced the porous structures inside the nanocomposites. Significantly, it revealed that the comprehensive performance of PVA-N2-2%GO consisted of PVA-N2 with the carbazate degree of substitution (DS) of 7% and the weight ratio (wt%) of 2% GO displayed 79% of tensile elongation and tensile strength of 5.96 N/mm2 (MPa) by tensile testing, glass transition temperature (Tg) of 60.8°C and decomposition temperature (Td) of 303.5°C by TGA and DSC, surface contact angle at 89.4 ± 2.1°, and electrical conductivity of 9.95 × 10−11 S/cm. The abovementioned comprehensive performance was enhanced with the increased amount of in situ rGO, contributed by the high DS of the carbazate group in PVA-N and high amount of GO. The rGO by in situ reduction was the main driving force for enhancing the multiple properties inside the nanocomposites.

Solubility of C-A-S-H phases with high degree of heavy metal ion substitution

Knowledge about interactions between cementitious materials and dissolved metal (Me) ions is key for environmental remediation and waste management, but thermodynamic data on this topic are still limited. We present solubility data for nanocrystalline C-A-S-H phases substituted by distinct Me ions with (Ca + Me)/(Si + Al) molar ratios from 0.86 to 1.04 and Ca2+ substitution of ∼ 48 mol% for Zn2+, ∼29 mol% for Co2+ and ∼ 27 mol% for Cu2+ in tobermorite-type Me-C-A-S-H. The solubility constants of the Me-C-A-S-H phases are significantly lower compared to pure C-A-S-H (logK = -8.3), ranging from logK = -8.6 to −11.3 for Co-C-A-S-H, logK = -9.1 to −11.6 for Cu-C-A-S-H and logK = -8.9 to −14.1 for Zn-C-A-S-H, as the Me content increases according to the expression:logKMe-C-A-S-H=0.11±0.03·%Mesubstitution-8.33±0.12;R2=0.89independent on the type of incorporated Me ion. Thus, newly-forming C-A-S-H phases have a high immobilization potential for aqueous Me ions. The novel solubility data open the door for thermodynamic modelling of Me ion mobility in aquatic media.

Degradation of Cellulose Acetate in Simulated Aqueous Environments: One‐Year Study

AbstractCellulose acetate (CA) is subjected to different aqueous environments (e.g., lake water, seawater, artificial seawater) under controlled laboratory conditions to investigate the degradation potential in natural water systems. The main changes in the CA films are detected during the first months of the 12‐month study. Approximately 5% and 10% weight losses are observed during the first month of aging at RT and at 60 °C, respectively. The temperature effect is rather negligible and the weight loss also does not significantly increase on prolonged aging. A quantitative high‐performance liquid chromatography analysis shows that this weight loss is mainly caused by deacetylation and depending on the aging conditions, 10–30% of the acetate groups are lost during the first 1–3 months of aging. Fourier transform infrared and nuclear magnetic resonance analyses further support this. It is well established that a high degree of substitution (DS) is the bottleneck for biodegradation of CA and a significantly higher biodegradation rate has been demonstrated for CA materials with degree of substitution, DS<2, compared to those with DS>2. The degree of deacetylation observed here is enough to decrease the DS to below 2, which can therefore have a significant effect on the subsequent biodegradation.

Preparation of pH-Responsive Poly(γ-glutamic acid) Hydrogels by Enzymatic Cross-Linking.

pH-responsive hydrogels are important for oral drug release applications, and they are increasingly demanded to reduce the adverse side effects of drug release and improve drug absorption. In this study, a new type of pH-responsive hydrogel comprised of poly(γ-glutamic acid) modified with tyramine (PGA-Tyr) was developed through enzymatic cross-linking in the presence of horseradish peroxidase (HRP) and hydrogen peroxide (H2O2). The gelation rate, stiffness, swelling behavior, and pore size of the resulting hydrogels were tuned by changing the concentrations of HRP and H2O2 or the degree of substitution (DS) of PGA-Tyr. The pH responsiveness of the hydrogels was evaluated by the swelling ratio in solutions with various pH values, and their pH responsiveness exhibited a good reversibility in pH 2.0 and 7.0 solutions. The degradation rate of the hydrogels in simulated intestinal fluid (SIF) was faster than that in simulated gastric fluid (SGF). Moreover, indomethacin (IM), a hydrophobic drug model, was encapsulated in the hydrogels by rapid in situ gelation, and the pH-dependent drug release of IM-loaded hydrogels was achieved in SGF and SIF. Importantly, when IM was entrapped in pluronic F-127 to form drug micelles, the burst release of the IM-micelle-loaded hydrogels with a high DS of PGA-Tyr was remarkably decreased in SGF, and sustained drug release was presented in SIF. Thus, pH-responsive PGA-based hydrogels have tremendous promise for biomedical applications, especially oral drug delivery.

Synthesis and characterization of sodium‐carboxymethylcellulose from cotton, powder, microcrystalline and nanocellulose

AbstractCotton cellulose, powder cellulose, microcrystalline cellulose and nanocellulose were carboxymethylated with monochloroacetic acid by the suspension method in an ethyl alcohol medium. The effects of reaction conditions such as cellulose materials, sodium hydroxide concentration, molar NaOH/anhydroglucose unit ratio, monochloroacetic acid consumption, reaction temperature and etherification time on product quality, especially the degree of substitution, degree of polymerization and water solubility of sodium‐carboxymethylcellulose, were studied. By controlling these parameters, completely water‐soluble sodium‐carboxymethylcellulose samples with a high degree of substitution within 0.75, 1.47, 0.88, and 1.23 were obtained from cotton cellulose, powder cellulose, microcrystalline and nanocellulose. The boundaries of complete solubility of the obtained sodium‐carboxymethylcellulose were at low degrees of substitution (0.6, 0.44, 0.43, 0.33) and degrees of polymerization (880, 490, 240, 150) obtained from cotton cellulose, powder cellulose, microcrystalline cellulose and nanocellulose, respectively.

Impact of the Incorporation of Nano-Sized Cellulose Formate on the End Quality of Polylactic Acid Composite Film.

Polylactic acid (PLA) films with good sustainable and biodegradable properties have been increasingly explored recently, while the poor mechanical property of PLA limits its further application. Herein, three kinds of nano-sized cellulose formate (NCF: cellulose nanofibril (CNF), cellulose nanocrystal (CNC), and regenerated cellulose formate (CF)) with different properties were fabricated via a one-step formic acid (FA) hydrolysis of tobacco stalk, and the influence of the properties of NCF with different morphologies, crystallinity index (CrI), and degree of substitution (DS) on the end quality of PLA composite film was systematically compared. Results showed that the PLA/CNC film showed the highest increase (106%) of tensile strength compared to the CNF- and CF-based films, which was induced by the rod-like CNC with higher CrI. PLA/CF film showed the largest increase (50%) of elongation at the break and more even surface, which was due to the stronger interfacial interaction between PLA and the CF with higher DS. Moreover, the degradation property of PLA/CNF film was better than that of other composite films. This fundamental study was very beneficial for the development of high-quality, sustainable packaging as an alternative to petroleum-based products.

Study on quantitative structure of oil from oily sludge by improved Brown-Ladner (B-L) method

Oily sludge is a mixture of crude oil, mud, and water contaminated by other organic matter. Oil from oily sludge was Soxhlet extracted using toluene solvent. Modern analytical techniques such as FT-IR, GPC, 1H-NMR were applied to characterize the structure of the extracted oil. The quantitative structure of the extracted oil was evaluated by improved B-L method. The average molecular weight and formula of the extracted oil were established. The extracted oil was found paraffin-based crude oil with aliphatic chain structure as main component, aromatic structure as a supplement, and aromatic rings were all the aliphatic side chain substituted unit rings with a high degree of substitution. This paper tried to apply the latest methods during the analysis of the sludge and extracted crude oil and provides theoretical basis of molecular structure for the recovery and utilization of oily sludge.

Preparation of Acetylated Acid-hydrolysis Modified Starch with High Degree of Substitution and Its Nanoparticles

In order to improve the application of acetylated starch in biomedicine and targeted drug delivery system, ordinary corn starch was selected as the material, acid hydrolysis in alcohol medium before the acetylation was introduced in the preparation of the acetylated acid-hydrolysis modified starch with high degree of substitution. The effects of acid-hydrolysis conditions on physicochemical properties of the modified starches were investigated by means of FT-IR, XRD, contact angle measurement, pasting curve and scanning electron microscope. Subsequently, anti-solvent precipitation was introduced in the preparation of the starch nanoparticles, and the size range was determined. Based on the results, under the condition of 70% ethanol（v/v）, 12 mol/L hydrochloric acid and 65 ℃, the substitution degree of acetylated starch increased from 0.84 to 1.33, the hydrophobicity significantly (P<0.05) improved and the particle size was reduced. Starch nanoparticles with a particle size of about 200 nm could be obtained through anti-solvent precipitation.

DESIGN, CHARACTERIZATION AND ENHANCED BIOAVAILABILITY OF HYDROXYPROPYLCELLULOSE-BASED NOVEL BIOCONJUGATES FOR INCLUSION OF A FLUOROQUINOLONE ANTIBIOTIC – GEMIFLOXACIN

Polysaccharides are beneficially used as drug carriers via prodrug formation and offer a mechanism for better effectiveness and delivery of the drug. The unique geometry of hydroxypropylcellulose (HPC), a polysaccharide, allows the attachment of drug molecules with a higher degree of substitution. Therefore, HPC-gemifloxacin conjugates, i.e., macromolecular prodrugs, were synthesized using acylation reagents, i.e., tosyl chloride and carbonyldiimidazole using N,N-dimethylacetamide as a solvent. The reactions were carried out at 80 °C under stirring for 24 h in inert environment. This strategy of reaction appeared efficient to obtain a high degree of drug substitution (DS = 0.42-1.34) on the polymer parent chain, as calculated by UV-visible spectrophotometry after hydrolysis of the samples. The method provides high efficacy as product yields were high (71-76%). Macromolecular prodrugs with different DS of gemifloxacin (GEM) designed were found soluble in organic solvents. The pharmacokinetic studies showed that the t1/2 and tmax values of GEM from HPC-GEM conjugate were considerably higher, which indicates improved bioavailability of the drug after conjugate formation.

Low temperature oxidized coke of the ultra-heavy oil during in-situ combustion process: Structural characterization and evolution elucidation

Fundamental knowledge on the evolution of low temperature oxidized coke was a prerequisite towards a deep understanding of coke deposition and subsequent combustion of ultra-heavy oils during in-situ combustion (ISC) process. This study investigated the structural characterization (oxidation behavior, elemental composition, functional groups, and morphology) and elucidated evolution mechanism of cokes generated from the low temperature oxidation/pyrolysis of the ultra-heavy oil during ISC process. The results shown that, compared with pyrolytic coke, the intermediate groups of C-O/C-OH (1260–1060 cm−1) were further oxidized into C = O (1850–1650 cm−1) groups and finally converted into C = C groups (“coke peak”, 1590 cm−1) in highly conjugated aromatic structures for oxidized cokes. Besides, the oxidized coking condition would result in a higher degree of substitution (γCHAr1, γCHAr4) of aromatic rings (900–700 cm−1) and promote the evolution of N- and S- functional groups. Although >78 % of C 1 s belonged to the graphitic carbon for four cokes, morphologies of oxidized cokes were relatively coarse with much looser distribution. In addition, the corresponding enthalpies were in the order cokeLTO3 (25.51 kJ·g−1) > cokeLTP (24.22 kJ·g−1) > cokeLTO2 (23.23 kJ·g−1) > cokeLTO1 (17.45 kJ·g−1), indicating a considerable contribution of low temperature oxidation reactions on derived coke morphology, oxidizability and exothermicity, which contained complicated and crucial dehydrogenation, crosslinking and polymerization reactions to accelerate coke evolution.

Cellulose laurate films containing curcumin as photoinduced antibacterial agent for meat preservation

Hydrophobic cellulose laurate (CL) with high degree of substitution has been successfully synthesized. The mechanical property, water-resistance, antimicrobial activity, barrier properties and food decontamination of cellulose-laurate-curcumin films (CL-Cux, x = 0.1, 0.5, and 1) were investigated. The results showed that the mechanical properties of CL-Cux hardly change after soaking in water for 24 h, probably due to the strong hydrophobicity of cellulose laurate. CL-Cu1 represented a good photoinduced antibacterial effect against S. aureus. After irradiation of white light at 60 mW·cm−2 for 20 min, the inhibition efficiency reached to 95 ± 2.02%, probably owing to the generated active 1O2. In comparison with CL-Cu1 stored in natural light, the bacteriostatic effect of CL-Cu1 in dark storage was better, and the inhibition rate of CL-Cu1 remained 80 ± 1.22 at 60th day. The stabler excited state of curcumin in hydrophobic cellulose laurate was probably assigned to inhibition of tautomerism or conformational transition, which was beneficial to the generation of singlet oxygen. CL-Cu1 can significantly inhibit the growth of TVBN and TVC values of chilled meat upon white light irradiation, indicating the potential application of cellulose-laurate-curcumin films in food decontamination.