A new design of colorimetric films using bacterial cellulose nanocrystals derived from nata de coco for sensing volatile organic compounds.

In this work, bacterial cellulose (BC) derived from Nata de Coco is a polysaccharide material, and it is further processed into bacterial cellulose nanocrystal (BCNC) via acid hydrolysis. Then BCNC is doped with transition metals to enhance its amine/hydrogen sulfide response. Therefore, the aim of this study is to investigate the use of transition metals as indicators to detect amine and hydrogen sulfide gas for efficiently monitoring food spoilage. BCNCs were treated with various concentrations of silver nitrate (AgNO3) and copper sulfate pentahydrate (CuSO4·5H2O). Then the dropwise addition of ascorbic acid was applied to reduce Ag+ and Cu2+ to Ag0 (silver nanoparticle) and Cu0 (copper nanoparticle), which refer to red brown and red wine colors, respectively. The results indicated that BCNC/Ag nanoparticles were spherical, while BCNC/Cu nanoparticles exhibited a rod-like structure. XRD results also presented the incorporation of Ag and Cu nanoparticles, as confirmed by both crystallography structures. Furthermore, UV-Vis spectra showed the adsorption bands at 422-430 nm and 626-629 nm, belonging to Ag and Cu nanoparticles. After H2S and ammonia gas exposure, BH/Ag and BH/Cu films turned black from brown and red. In conclusion, transition metal-doped BCNCs exhibit potential for innovative food spoilage gas sensors.

Fabrication of a colorimetric film based on bacterial cellulose/metal coordination framework composite for monitoring food spoilage gas.

A newly designed colorimetric sensing film has been developed to determine the spoilage gas from food deterioration. The fabrication of sensing film used for food labels based on bacterial cellulose and carboxymethyl cellulose composite film (BC/CMC) incorporated with Bis(imidazolium) tetrachlorocuprate, HIm2CuCl4 was focused. The BC/CMC composite films were prepared by vacuum filtration and then dipped into the (5-20 % w/w) HIm2CuCl4 solution. Subsequently, they were dried at 60 °C to obtain the BC/CMC-Cu film. For monitoring fish freshness, the TVB-N level was considered an indicator of determining fish spoilage. In addition, the color change was evaluated and expressed as Lab color values and total color difference (TCD). According to the sensing response, the TCD values of the sensing films had continuously changed, corresponding to the ammonia gas, which is one of the TVB-N gases. Based on the variations in Lab color values exposed to ammonia gas at room temperature, the film color shifted from the initial lime green color to the final blue color due to the substitution of metal-ligand bonding. Finally, this colorimetric sensing film can be employed as a potential food freshness indicator in intelligent packaging.

Solution plasma synthesis of bacterial cellulose acetate derived from nata de coco waste incorporated with polyether block amide.

Cellulose acetate (CA), one of the most important cellulose derivatives, is used in various applications especially in membranes, films, fibers, filters, and polymers. Because of the tough and flexible character and resistance to acids of CA, bacterial cellulose acetate (BCA) has been used as reinforcement for high performance separator purposes. In this study, BCA was synthesized through the heterogeneous acetylation in acetic solution with H2SO4 as catalyst by solution plasma process (SPP) of bacterial cellulose (BC) extracted form nata de coco waste. The SPP was considered as mild, simple, and fast method for many kinds of synthesis. The solution plasma time was studied to obtain considerably high DS values (in this work, DS = 1.95). The high DS values are an important feature when considering an environmental factor, good liquid transport and excellent absorption. Furthermore, the BCA incorporated with poly ether block amide by electrospinning method is successfully fabricated as nanofibrous membranes. The proposed PEBAX/BCA nanofibrous membranes display superior sufficient porosity (74.7%), exceptional liquid electrolyte uptake (364.6%), sufficient thermal dimensional stability at 150 °C, great electrochemical stability (discharge capacity at 0.2C = 102.14 mAh g-1), and high ionic conductivity (9.12 × 10-3 S/cm). Furthermore, the PEBAX/BCA nanofibrous membranes can be used as high-performance separators enhancing its safety for Li-ion battery applications.

A Single Crystal Hybrid Ligand Framework of Copper(II) with Stable Intrinsic Blue-Light Luminescence in Aqueous Solution.

Single-crystal solid-liquid dual-phase hybrid organic-inorganic ligand frameworks with reversible sensing response facilitated by external stimuli have received significant attention in recent years. This report presents a significant leap in designing electronic structures that display reversible dual-phase photoluminescence properties from single-crystal hybrid ligand frameworks. Three-dimensional Cu(C3N2H4)4Cl2 complex frameworks were formed through the intermolecular hydrogen bonding and π⋯π stacking supramolecular interactions. The absorption band peaks at 627 nm were assigned to d-d transition showing 10Dq = 15,949 cm-1 and crystal field stabilization energy (CFSE) = 0.6 × 10Dq = 114.4 kJmol-1, while the ligand-to-metal charge transfer (LMCT) of complexes was displayed at 292 nm. The intense luminescence band results from LMCT present at 397 nm. Considering its structure, air stability, framework forming and stable luminescence in aqueous solution, the Cu(C3N2H4)4Cl2 complex shows potential for luminescence Cu-based sensors using emission intensity to detect heavy metal ion species.

Influence of hydrogen sulfide gas concentrations on LOD and LOQ of thermal spray coated hybrid-bacterial cellulose film for intelligent meat label.

Hybrid nanocomposite thin film for hydrogen sulfide (H2S) gas sensor based on bacterial cellulose nanocrystals (BCNCs) has resulted in high demand of environmentally friendly nanomaterials. Films were prepared using thermal spray coating that sprayed hybrid nanocomposite suspension based on silver nanoparticles (AgNPs)-loaded BCNCs's surface and alginate-molybdenum trioxide (MoO3NPs) onto PET substratum. In this study, a novel food package label characterized as H2S gas sensor for meat spoilage is based on an optically transparent coated film with thickness ranging from 0.73 to 2.18 µm. Sensor characteristics with different suspension concentrations and various H2S gas concentrations were evaluated. The highest sensitivity to H2S with the limit of detection (LOD) (3.27 ppm) and the limit of quantification (LOQ) (10.94 ppm) was exhibited in 1%w/v suspension. Label prototypes which respond as visible color changes through naked-eye to H2S gas released during meat spoilage, monitored at 4 °C and varying storage times were conducted.

Novel bacterial cellulose nanocrystals/polyether block amide microporous membranes as separators for lithium-ion batteries.

Bacterial cellulose nanocrystals (BCNCs) were extracted from nata de coco waste and underwent sulphuric acid (H2SO4) hydrolysis for use as a reinforcement giving thermal and dimensional stability to polyether block amide (PEBAX) as a polymer matrix for the fabrication of BCNCs/PEBAX microporous membranes. The H2SO4-hydrolysis of BCNCs yielded rod-like/needle-like BCNCs and negatively charged surfaces, resulting from the generated surface sulfate groups on the bacterial cellulose (BC), which may be competent for numerous applications. The non-solvent induced phase separating (NIPS) and subsequent film casting methods were used to prepare the BCNCs/PEBAX microporous membranes. The obtained films were characterized with regards to their structure in terms of the content of crystalline phases, as well as their ionic transport and performance at elevated temperatures. The presence of the BCNCs fillers resulted in a good thermal and dimensional stability up to 150 °C and correlated with no membrane shrinkage. For NIPS membranes, the formation of a rigid cellulosic network within the matrix was emphasized and attributed to the thermal stabilization at temperatures above the melting temperature. In addition, the wettability, ionic conductivity, and thermal stability were investigated in BCNCs/PEBAX membranes filled with different amounts of BCNCs. Thus, the BCNCs/PEBAX membranes derived via NIPS had a remarkably good ionic conductivity, within the range of 10-2-10-3 S/cm, with up to 56.8% porosity. Such porous membranes are considered as an important and interesting candidate for the replacement of the commercial polyolefin-based microporous separator in lithium-ion batteries due to their superior electrochemical performances and the observed reinforcement effect.

Fabrication of hybrid thin film based on bacterial cellulose nanocrystals and metal nanoparticles with hydrogen sulfide gas sensor ability.

The nanocrystalline structures of bacterial cellulose (BC) are described as "environmentally friendly green nanomaterials". Bacterial cellulose (BC) was produced from Gluconacetobacter xylinus in pellicle form with a large bundle of fibers were acid hydrolyzed to obtain bacterial cellulose nanocrystals (BCNCs). The H2SO4 acid-hydrolyzed BCNCs were evaluated for their smallest crystallite size and hydrodynamic size, highly negative ζ-potential value, and the highest specific surface area to interact with metallic nanoparticles. Hybrid thin film of BCNCs based surface-loaded silver nanoparticles (AgNPs) and alginate-molybdenum trioxide nanoparticles (MoO3NPs) was developed for hydrogen sulfide (H2S) gas sensor. Sensor characteristics were investigated as well as its response with H2S gas. The film was successfully detected H2S gas. The color of the film changed by the shift of oxidation number of MoO3NPs. Once activated by AgNPs, MoO3NPs was readily reduced to a colored sub-oxide by atomic hydrogen that produced and received from reaction of H2S gas.

Sulfonation of dialdehyde cellulose extracted from sugarcane bagasse for synergistically enhanced water solubility.

Sulfonated cellulose (SC) was successfully derived from microcrystalline cellulose (MCC) extracted from sugarcane bagasse, which is a type of agricultural waste. The obtained MCC was first modified by oxidation using sodium periodate in order to cleave the carbon-carbon bonds at the C2 and C3 of the pyranose ring to form 2,3-dialdehyde cellulose. These activated aldehyde groups significantly facilitated the sulfonation carried out using potassium metabisulfite. The sulfonic acid group contents, surface morphology, and water solubility of the obtained products were characterized by titration, field-emission scanning electron microscopy, UV-vis spectroscopy, and zeta potential. High sulfonic acid group content was achieved for the obtained SC samples (i.e., 305-689 µmol/g). The increase in the sulfonic acid group content resulted in the gradual change in the surface morphology and water solubility of the SC samples. The obtained results imply that sugarcane bagasse is a promising raw material for the production of SC with good water solubility.

Well-Defined Cationic N-[3-(Dimethylamino)propyl]methacrylamide Hydrochloride-Based (Co)polymers for siRNA Delivery.

Cationic glycopolymers have shown to be excellent candidates for the fabrication of gene delivery devices due to their ability to electrostatically interact with negatively charged nucleic acids and the carbohydrate residues ensure enhanced stability and low toxicity of the polyplexes. The ability to engineer the polymers for optimized compositions, molecular weights, and architectures is critical in the design of effective gene delivery vehicles. Therefore, in this study, the aqueous reversible addition-fragmentation chain transfer polymerization (RAFT) was used to synthesize well-defined cationic glycopolymers with various cationic segments. For the preparation of cationic parts, N-[3-(dimethylamino)propyl]methacrylamide hydrochloride (DMAPMA·HCl), water-soluble methacrylamide monomer containing tertiary amine, was polymerized to produce DMAPMA·HCl homopolymer, which was then used as macroCTA in the block copolymerization with two other methacrylamide monomers containing different pendant groups, namely, 2-aminoethyl methacrylamide hydrochloride (AEMA) (with primary amine) and N-(3-aminopropyl) morpholine methacrylamide (MPMA) (with morpholine ring). In addition, statistical copolymers of DMAPMA.HCl with either AEMA or MPMA were also synthesized. All resulting cationic polymers were utilized as macroCTA for the RAFT copolymerization with 2-lactobionamidoethyl methacrylamide (LAEMA), which consists of the pendent galactose residues to achieve DMAPMA·HCl-based glycopolymers. From the in vitro cytotoxicity study, the cationic glycopolymers showed better cell viabilities than the corresponding cationic homopolymers. Furthermore, complexation of the cationic polymers with siRNA, cellular uptake of the resulting polyplexes, and gene knockdown efficiencies were evaluated. All cationic polymers/glycopolymers demonstrated good complexation ability with siRNA at low weight ratios. Among these cationic polymer-siRNA polyplexes, the polyplexes prepared from the two glycopolymers, P(DMAPMA65-b-LAEMA15) and P[(DMAPMA65-b-MPMA63)-b-LAEMA16], showed outstanding results in the cellular uptake, high EGFR knockdown, and low post-transfection toxicity, suggesting the great potential in siRNA delivery of these novel glycopolymers.

Thermo-Responsive Poly(N-Isopropylacrylamide)-Cellulose Nanocrystals Hybrid Hydrogels for Wound Dressing.

Thermo-responsive hydrogels containing poly(N-isopropylacrylamide) (PNIPAAm), reinforced both with covalent and non-covalent interactions with cellulose nanocrystals (CNC), were synthesized via free-radical polymerization in the absence of any additional cross-linkers. The properties of PNIPAAm-CNC hybrid hydrogels were dependent on the amounts of incorporated CNC. The thermal stability of the hydrogels decreased with increasing CNC content. The rheological measurement indicated that the elastic and viscous moduli of hydrogels increased with the higher amounts of CNC addition, representing stronger mechanical properties of the hydrogels. Moreover, the hydrogel injection also supported the hypothesis that CNC reinforced the hydrogels; the increased CNC content exhibited higher structural integrity upon injection. The PNIPAAm-CNC hybrid hydrogels exhibited clear thermo-responsive behavior; the volume phase transition temperature (VPTT) was in the range of 36 to 39 °C, which is close to normal human body temperature. For wound dressing purposes, metronidazole, an antibiotic and antiprotozoal often used for skin infections, was used as a target drug to study drug-loading and the release properties of the hydrogels. The hydrogels showed a good drug-loading capacity at room temperature and a burst drug release, which was followed by slow and sustained release at 37 °C. These results suggested that newly developed drugs containing injectable hydrogels are promising materials for wound dressing.