Pectin-mucin interactions: Insights from fluorimetry, thermodynamics and dual (static and dynamic) quenching mechanisms.

Binary systems of citrus peel pectin (a major food carbohydrate) and mucin (a principal oral-gastrointestinal glycoprotein) are studied, as to understand the interactions and thermodynamics between food and biofluids during oral processing and digestion. The fluorimetry emission spectra of mucin were quenched by pectin addition at 293, 301, 310 and 318 K, indicating direct contact between the two macromolecular populations. A red shift, suggesting pectin-induced alterations on mucin conformation, has been observed at 318 K. Intensity-based Stern - Volmer plots fitted second-order polynomial equations, suggesting the coexistence of both static and dynamic quenching, while the increase of the slopes with temperature points to the predominance of dynamic phenomena. Time-resolved fluorescence measurements also point to dynamic quenching related to transient interactions, rather than to specific bonding. Thermodynamic analysis yields negative free energy changes in all cases, with positive changes for enthalpy and large positive values for TΔS. These are in agreement with the Stern - Volmer analysis, suggesting the predominance of transient, dynamic (here entropic) interactions. These provide an image of mucin interacting with pectin macromolecules during the oral processing and digestion of foods, and can relate to the texture, flavor (e.g. astringency) and bioavailability of polysaccharide-based foods.

Hydrostability, mechanical resilience, and biodegradability of paper straws fabricated through lignin-based polyurethane and chitosan binary emulsion bonding.

This study focuses on enhancing the strength and water stability of paper straws through a novel approach involving a binary emulsion of lignin-based polyurethane and chitosan. Kraft lignin serves as the raw material for synthesizing a blocked waterborne polyurethane, subsequently combined with carboxylated chitosan to form a stable binary emulsion. The resulting emulsion, exhibiting remarkable stability over at least 6 months, is applied to the base paper. Following emulsion application, the paper undergoes torrefaction at 155 °C. This process deblocks isocyanate groups, enabling their reaction with hydroxyl groups on chitosan and fibers, ultimately forming ester bonds. This reaction significantly improves the mechanical strength and hydrophobicity of paper straws. The composite paper straws demonstrate exceptional mechanical properties, including a tensile strength of 47.21 MPa, Young's modulus of 4.33 GPa, and flexural strength of 32.38 MPa. Notably, its water stability is greatly enhanced, with a wet tensile strength of 40.66 MPa, surpassing commercial paper straws by 8 folds. Furthermore, the composite straw achieves complete biodegradability within 120 days, outperforming conventional paper straws in terms of environmental impact. This innovative solution presents a promising and sustainable alternative to plastic straws, addressing the urgent need for eco-friendly products.

Polysaccharide-based nanoassemblies: From synthesis methodologies and industrial applications to future prospects.

Polysaccharides, due to their remarkable features, have gained significant prominence in the sustainable production of nanoparticles (NPs). High market demand and minimal production cost, compared to the chemically synthesised NPs, demonstrate a drive towards polysaccharide-based nanoparticles (PSNPs) benign to environment. Various approaches are used for the synthesis of PSNPs including cross-linking, polyelectrolyte complexation, and self-assembly. PSNPs have the potential to replace a wide diversity of chemical-based agents within the food, health, medical and pharmacy sectors. Nevertheless, the considerable challenges associated with optimising the characteristics of PSNPs to meet specific targeting applications are of utmost importance. This review provides a detailed compilation of recent accomplishments in the synthesis of PSNPs, the fundamental principles and critical factors that govern their rational fabrication, as well as various characterisation techniques. Noteworthy, the multiple use of PSNPs in different disciplines such as biomedical, cosmetics agrochemicals, energy storage, water detoxification, and food-related realms, is accounted in detail. Insights into the toxicological impacts of the PSNPs and their possible risks to human health are addressed, and efforts made in terms of PSNPs development and optimising strategies that allow for enhanced delivery are highlighted. Finally, limitations, potential drawbacks, market diffusion, economic viability and future possibilities for PSNPs to achieve widespread commercial use are also discussed.

In-situ CBM3-modified bacterial cellulose film with improved mechanical properties.

Cellulose materials have poor wet strength and are susceptible to acidic or basic environments. Herein, we developed a facile strategy to modify bacterial cellulose (BC) with a genetically engineered Family 3 Carbohydrate-Binding Module (CBM3). To assess the effect of BC films, water adsorption rate (WAR), water holding capacity (WHC), water contact angle (WCA), and mechanical and barrier properties were determined. The results showed that CBM3-modified BC film exhibited significant strength and ductility improvement, reflecting improved mechanical properties of the film. The excellent wet strength (both in the acidic and basic environment), bursting strength, and folding endurance of CBM3-BC films were due to the strong interaction between CBM3 and fiber. The toughness of CBM3-BC films reached 7.9, 28.0, 13.3, and 13.6 MJ/m3, which were 6.1, 1.3, 1.4, and 3.0 folds over the control for conditions of dry, wet, acidic, and basic, respectively. In addition, its gas permeability was reduced by 74.3 %, and folding times increased by 56.8 % compared with the control. The synthesized CBM3-BC films may hold promise for future applications in food packaging, paper straw, battery separator, and other fields. Finally, the in situ modification strategy used to BC can be successfully applied in other functional modifications for BC materials.

Magnetic nanocellulose alginate hydrogel beads as potential drug delivery system.

Magnetic nanocellulose alginate hydrogel beads are produced from the assembly of alginate and magnetic nanocellulose (m-CNCs) as a potential drug delivery system. The m-CNCs were synthesized from cellulose nanocrystals (CNCs) that were isolated from rice husks (RH) by co-precipitation method and were incorporated into alginate-based hydrogel beads with the aim of enhancing mechanical strength and regulating drug release behavior. Ibuprofen was chosen as a model drug. The prepared CNCs, m-CNCs and the alginate hydrogel beads were characterized by various physicochemical techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM) and vibrating sample magnetometer studies (VSM). Besides the magnetic property, the presence of m-CNCs increased the integrity of the alginate hydrogel beads and the swelling percentage. The drug release study exhibited a controlled release profiles and based on the drug release data, the drug release mechanism was analyzed and discussed based on mathematical models such as Korsmeyer-Peppas and Peppas-Sahlin.

Immobilization of ß-galactosidase on surface modified cobalt/multiwalled carbon nanotube nanocomposite improves enzyme stability and resistance to inhibitor.

The present study aimed to work out a high yield procedure for immobilization of Aspergillus oryzae ß-galactosidase on polyaniline cobalt multiwalled carbon nanotubes nanocomposite (PANI/Co/MWCNTNC) by physical adsorption and covalent attachment via glutaraldehyde. The binding was confirmed by scanning and transmission electron microscopy along with Fourier transform-infrared spectroscopy. The immobilization yields obtained for adsorbed and cross-linked enzymes were 93% and 97%, respectively. The covalently immobilized enzyme was remarkably more stable at extremes of pH and temperature compared to native and adsorbed enzymes. The Ki values were found to increase ten-folds for covalently immobilized ß-galactosidase indicating that this immobilized enzyme was markedly more resistant to galactose inhibition. The covalently attached enzyme retained 92% activity after its 10th successive reuse compared to the adsorbed ß-galactosidase which exhibited 74% of its initial activity. Furthermore, no significant change was noticed in the band intensity of pBR322 plasmid when exposed to free and bound nanocomposite. The covalently bound enzyme exhibited superiority in terms of stability and reusability when compared to the adsorbed and native ß-galactosidase. The results, presented here demonstrate an efficient method of immobilization of ß-galactosidase on PANI/Co/MWCNTNC in order to construct a convenient and novel biosensor for the detection of lactose concentration.

Synthesis, characterization, antimicrobial activity and applications of polyanilineTi(IV)arsenophosphate adsorbent for the analysis of organic and inorganic pollutants.

A novel polyaniline based composite cation exchange material has been synthesized by simple chemical route and characterized on the basis of sophisticated techniques. XRD and SEM analyses reveal the amorphous morphology of the material. The partition coefficient studies of different metal ions on the material were performed in DMW and diverse concentrations of HClO4 solutions. On the basis of high Kd values some significant separations of heavy toxic metal ions were achieved from synthetic mixtures as well as tap water samples by using columns of this exchanger. For the optimum adsorption of dye on the material, the effect of various parameters along with Langmuir and Freundlich adsorption isotherm were examined. The observed result of conducting measurement indicates that the material covers semiconductor range. The photochemical degradation of industrial dyes and antimicrobial activity were also investigated which show significant results than some of the known antibiotics. On the basis of good ion exchange capacity along with photochemical degradation and microbial activity, polyanilineTi(IV)arsenophosphate can be considered as an excellent conducting material for the treatment metal ions and degradation of organic pollutants.

Ion exchangers as adsorbents for removing metals from aquatic media.

A polyaniline-based composite cation-exchange material was synthesized by way of sol-gel method and studied to explore its analytical and environmental applications. It was characterized by using instrumental analyses [Fourier transform infrared (spectrometer), X-ray, thermogravimetric analysis/differential thermal analysis, standard electron microscopy, and transmission electron microscopy]. Physicochemical studies, such as ion-exchange capacity, pH titrations, and chemical stability, along with effect of eluent concentration and elution, were also performed to exploit the ion-exchange capabilities. pH titration studies showed that the material presents monofunctional strong cation-exchange behavior. This nanocomposite material is semicrystalline in nature and exhibits improved thermal and chemical stability. The partition coefficient studies of different metal ions in the material were performed in demineralised water and different surfactant media, and it was found to be selective for Pb(II) and Hg(II) ions. To exploit the usefulness of the material as an adsorbent, some important quantitative binary separations of metal ions were performed on polyaniline Zr(IV) molybdophosphate columns. This composite cation exchanger can be applied for the treatment of polluted water to remove heavy metals.

Synthesis and characterization of nano-composite ion-exchanger; its adsorption behavior.

A novel organic-inorganic nanocomposite cation-exchanger has been synthesized via sol-gel method. It was characterized on the basis of FTIR, XRD, SEM, TEM, AFM and Raman studies. The structural studies reveal semi-crystalline nature of the material with the particle size ranging from 1-5 nm. Physiochemical properties such as ion-exchange capacity, chemical and thermal stability of composite material have also been determined. Bifunctional behavior of the material has been indicated by its pH titrations curves. The nanocomposite material exhibits improved thermal stability, higher ion-exchange capacity and better selectivity for toxic heavy metals. The ion-exchange material shows an ion-exchange capacity of 1.8 meq g(-1) for Na(+) ions. Sorption behavior of metal ions on the material was studied in different solvents. The cation exchanger was found to be selective for Pb(II), Hg(II) and Zr(IV) ions. The limit of detection (LOD) and the limit of quantification (LOQ) for Pb(II) ion was found to be 0.85 and 2.85 µg L(-1). Analytically important separations of heavy metal ions in synthetic mixtures as well as industrial effluents and natural water were achieved with the exchanger. The practical utility of polyanilineZr(IV)sulphosalicylate cation exchanger has been established for the analysis and recovery of heavy metal ions in environmental samples.