Novel bionanocomposite films based on graphene oxide filled starch/polyacrylamide polymer blend: structural, mechanical and water barrier properties

Starch spectra of Ampelopteris prolifera (Retz.) Copel, a new addition to the existing lexicon and its comparison with a local potato cultivar (Solanum tuberosum L. cv. Kufri Jyoti)

Novel kinds of starch spectra were generated from a lesser-known plant, making this investigation unique. The recent trend of starch characterization shows the establishment of novel bioresources from nonconventional unexplored databases. The present endeavor was made to obtain the starch fingerprint of Ampelopteris prolifera (rhizome) belonging to seedless vascular plants. For comparison, a commercial local cultivar of potato (Kufri Jyoti) was taken. The starch particle of A. prolifera shows much uniqueness depicting its novelty viz., crystallinity index of 60.04 %, powder diffractogram at (2θ scale)17.57° to 39.78°; this diffractogram pattern is reported from this study as newer one i.e. R type(whereas potato starch is CB type); characteristic peak at 2θ = 20.07° suggests starch-lipid complex formation and V type crystallinity (i.e. RS 5 type); FTIR spectra showing the presence of more short chain branching; high gelatinization temperature(84.62 ± 0.10), particle size and zeta value of A. prolifera is 4.00 ± 0.81 μm and - 18.91 ± 3.58 mV respectively. Bragg's peak from the single crystal X-ray diffraction has been generated for the first time of A. prolifera. Extraction of the starch particle was performed in chilled water. Therefore, the present study suggests wide-spectrum commercial utility and cost-effective production.

Starch/polyvinyl alcohol with ionic liquid/graphene oxide enabled highly tough, conductive and freezing-resistance hydrogels for multimodal wearable sensors

With ever-growing demand for eco-friendly materials for wearable electronics, biopolymer-based hydrogels have drawn significant attention. As one of the most abundant and biodegradable biopolymers, starch-based hydrogels have a great potential for wearable electronics. However, mechanical fragility, low conductivity and subzero freeze restrict their applications. Here, a multifunctional hydrogel was facilely fabricated by integrating ionic liquid and graphene oxide into potato starch/polyvinyl alcohol skeleton via a green physical-crosslinking method. The abundant hydrogen-bond and electrostatic interactions endowed the hydrogel with excellent stretchability (657.5 %), strength (0.64 MPa), high conductivity (1.98 S·m-1) and good anti-freezing property (< -20 °C). Multiple characterizations and theoretical simulation (DFT) were combined to understand and confirm the interactions among different components. Taking advantage of these properties, multimodal wearable sensors were constructed for sensing tension (gauge factor: 6.04), compression (gauge factor: 3.27) and temperature (sensitivity: 0.71 %/°C), which are applied for monitoring human motion, daily-life pressure and body temperature. The sensor had a good anti-fatigue property with stable signals during 2000 cycles. Moreover, the sensor can effectively recognize handwriting and perform human-computer interaction. This work provides a promising route to develop sustainable and multifunctional biopolymer hydrogels for wearable sensors with versatile applications in human health, exercise monitors and soft robots.

Effect of enzymatic hydrolysis on digestibility and morpho-structural properties of hydrothermally pre-treated red rice starch

The objective of this work was to evaluate the effects of enzymatic hydrolysis on digestibility and morphological and structural properties of hydrothermally pre-treated (HPT) red rice starch. The pre-treatments were performed in autoclave and cooking for the modification of rice grains and native starch. In vitro starch digestibility was performed consecutively and semi-simultaneously using α-amylase and amyloglucosidase. A first-order mathematical model was used to adjust the hydrolysis kinetic data, which made it possible to calculate the surface area, hydrolysis index, and glycemic index of the starch. Scanning electron microscopy images (SEM), Fourier transform infrared (FTIR) spectra and X-ray diffraction (XRD) were also performed to investigate the characteristics of the post-hydrolysis starch samples. The autoclaved starch HSS-A3, which was subjected to 121 °C/1.08 bar for 10 min, showed the highest in vitro digestibility values (80.08 %). Both starch samples showed increase of particle size and enzymatic digestibility after HPT. FTIR spectra of the starch samples showed that there was no appearance of new functional groups. However, XRD evidenced that HPT changed the intensity of the peaks and the type of crystallinity was changed for autoclaved starch (A3) from type A to Vh, with crystallinity ranging from 21.71 % to 26.42 %. The semi-simultaneous approach showed more advantages due to the highest in vitro digestibility as well as reducing the processing time and use of reagents.

Facile synthesis of starch and tellurium doped SrO nanocomposite for catalytic and antibacterial potential: In silico molecular docking studies

A chemical co-precipitation route was used to synthesize novel strontium oxide (SrO), SrO-starch composite and various tellurium (Te) concentrations were incorporated in SrO-starch composite. This study aims to enhance the catalytic activities and bactericidal behavior of SrO, SrO-starch composite with different percentage concentrations of Te doping and a fixed amount of starch nanoparticles. XRD affirmed that the dopant contribution was investigated to improve crystallinity. Surface morphological characteristics and elemental composition evaluation were determined using an FE-SEM and EDS exhibit a doping concentration of an element in the synthesized products. The configuration of Sr-O-Sr bonds and molecular vibrations has been indicated by FTIR spectra. In addition, dye degradation of prepared samples was investigated through catalytic activity (CA) in the existence of NaBH₄ act as a reduction representative. The Te-doped SrO-starch composite indicates superior catalytic activity and shows a degradation of Methylene blue dye (91.4 %) in an acidic medium. The synthesis nanocatalyst demonstrated impressive antibacterial activity against Staphylococcus aureus (S. aureus) at high and low concentrations exhibiting zones of inhibition 9.30 mm as compared to ciprofloxacin. Furthermore, molecular docking studies of synthesized nanocomposites were performed against selected enzyme targets, i.e., β-lactamase_E.coli and DNA Gyrase_E.coli.

Cellulose nanofibrils reinforced xylan-alginate composites: Mechanical, thermal and barrier properties

Cellulose nanofibrils (CNFs) can be used as an effective reinforcement material for biopolymer films intended for food packaging applications. The aim of this study was to improve the mechanical and barrier properties of xylan-alginate films by incorporating CNFs into the xylan-alginate matrix. CNFs was produced from maize stalk waste residues through a combination of chemical and mechanical treatment. The CNFs was incorporated into the xylan-alginate matrix between 1 and 10 wt%. The suitability of the CNFs reinforced composite films for food packaging applications was investigated by testing the mechanical, thermal and optical properties as well as the moisture sorption, solubility and water vapour permeability of the films. The CNFs produced had fibre diameters between 10 and 80 nm and transmission electron microscopy images showed that the CNFs were highly entangled hence forming a web like structure. It was found that the incorporation of CNFs into the xylan-alginate matrix increased the tensile strength and Young's modulus of the films. The incorporation of CNFs improved the WVP of the films but did not show any significant effect on the thermal properties of the films.

Surface modification of highly hydrophobic polyester fabric coated with octadecylamine-functionalized graphene nanosheets

This study focuses on the design of highly hydrophobic polyester fabrics (PET) coated with organophilic graphene nanosheets (G-ODA) through a simple, cost-effective and scalable coating method. The organophilic graphene oxide was successfully synthesized by covalently grafting a long chain fatty amine on its surface and was fully characterized by various physicochemical techniques. G-ODA was coated at different loadings onto the PET fabric ranging from 1 to 7 wt% to produce uniformly dispersed PET@G-ODA fabrics with multifunctional performances. FTIR has confirmed the formation of strong interfacial interaction between the PET and G-ODA functional groups. Moreover, the produced PET@G-ODA fabrics resulted in achieving enhanced thermal stability as well as excellent water repellency compared to the pristine PET. Water contact angle measurements showed a tremendous enhancement of surface hydrophobicity up to 148° with 7 wt% loading of G-ODA. Tensile strength tests revealed that our fabric exhibited excellent mechanical properties compared to neat PET. In addition, the designed PET@G-ODA fabrics demonstrated excellent oil/water separation efficiency for different oil/water mixtures. The obtained results are very promising in terms of designing and producing functional PET fabrics with improved thermal and surface proprieties.

This study focuses on the design of highly hydrophobic polyester fabrics (PET) coated with organophilic graphene nanosheets (G-ODA) through a simple, cost-effective and scalable coating method.

Entropy and Random Walk Trails Water Confinement and Non-Thermal Equilibrium in Photon-Induced Nanocavities

Molecules near surfaces are regularly trapped in small cavitations. Molecular confinement, especially water confinement, shows intriguing and unexpected behavior including surface entropy adjustment; nevertheless, observations of entropic variation during molecular confinement are scarce. An experimental assessment of the correlation between surface strain and entropy during molecular confinement in tiny crevices is difficult because strain variances fall in the nanometer scale. In this work, entropic variations during water confinement in 2D nano/micro cavitations were observed. Experimental results and random walk simulations of water molecules inside different size nanocavitations show that the mean escaping time of molecular water from nanocavities largely deviates from the mean collision time of water molecules near surfaces, crafted by 157 nm vacuum ultraviolet laser light on polyacrylamide matrixes. The mean escape time distribution of a few molecules indicates a non-thermal equilibrium state inside the cavity. The time differentiation inside and outside nanocavities reveals an additional state of ordered arrangements between nanocavities and molecular water ensembles of fixed molecular length near the surface. The configured number of microstates correctly counts for the experimental surface entropy deviation during molecular water confinement. The methodology has the potential to identify confined water molecules in nanocavities with life science importance.

Novel high-gluten flour physically cross-linked graphene oxide composites: Hydrothermal fabrication and adsorption properties for rare earth ions

Graphene oxide (GO) nanosheets were immobilized and cross-linked by high-gluten flour (HGF), and a series of biomass-GO composites with various HGF-to-GO mass ratios were fabricated through a one-step hydrothermal method. The HGF-GO composites were used as novel adsorbents to adsorb rare earth ions (REE³⁺: La³⁺, Yb³⁺, Y³⁺, Er³⁺ and Nd³⁺) from aqueous solutions, and their adsorption properties were also investigated detailly. To evaluate the physicochemical properties of HGF-GO composites and further understand the mechanisms of adsorption of REE³⁺ onto HGF-GO composites, the HGF-GO composites were characterized by scanning electron microscopy (SEM), thermal gravimetric analyzer (TGA), Raman spectroscopy and Fourier transform infrared (FT-IR) spectroscopy. Several important condition parameters including contact time, initial REE³⁺concentrations, solution pH values and temperature that might affect the adsorption process were studied in detail. The maximum adsorption capacities of HGF-GO_1:1 composite toward La³⁺, Yb³⁺, Y³⁺, Er³⁺ and Nd³⁺ were 30.32, 36.64, 32.84, 42.36 and 48.68 mg g^-1, respectively. The experimental data indicated that the adsorption of REE³⁺ onto HGF-GO_1:1 was well fitted by the pseudo-second order kinetic model and the Langmuir isotherm model, and the adsorption process was a spontaneous and endothermic reaction. The HGF-GO_1:1 composite could be well regenerated and reused after five adsorption-desorption cycles, and its removal efficiency for Yb³⁺ remained as a constant of 100%.