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We report on production of novel quaternary nanocomposite films based on thermoplastic starch (TPS, 8% w/v) derived from cassava, cocoa butter, (CB, 30% wt.%), and lemongrass essential oil (LEO, 1:1) nanoemulsions reinforced with different concentrations of brewery spent grain (BSG, 5 or 10 wt.%) fibers, by continuous casting. The chemical composition, the morphological, thermal, mechanical properties, film barrier, biodegradability in the vegetable compound, in addition to the application in chocolates, have been widely studied. The addition of CB, LEO, and BSG caused relevant changes in the starch-based films, such as increased extensibility (from 2.4-BSG5 to 9.4%-BSG10) and improved barrier to moisture (2.9 and 2.4 g.mm.kPa-1 .h-1 .m-2 ). Contrastingly, the thermal stability of the starch film was slightly decreased. The biodegradability of the herein developed quaternary nanocomposite films was the same as that of TPS films, eliminating concerns on the supplementation with active ingredients that are expected to have some biocidal effect. Despite checking antimicrobial activity only by contact under the biocomposites, chocolates packed with the films were well accepted by consumers, especially the samples of white chocolate stored in the BSG5 biocomposite. Overall, this new approach towards quaternary active, biodegradable films produced in a pilot-scale lamination unit was successful in either improving or at least maintaining the essential properties of TPS-based films for food packaging applications, while providing them with unique features and functionalities. PRACTICAL APPLICATION: This contribution relates to new approach toward quaternary films produced in a pilot-scale lamination unit. It relates to sustainability as it is both biodegradable and based on plant biomass, as well as produced via a clean, through high-yield process. The four components of the edible films we developed provide it with good in properties performance, as both a passive barrier (i.e. purely physical), and active, related to the sensory attributes of food, essential to be applied in food packaging. The valorization of a BSG also adds to the relevance of our contribution within the circular bioeconomy framework.

Injured bone tissues can be healed with scaffolds, which could be manufactured using the fused deposition modeling (FDM) strategy. Poly(lactic acid) (PLA) is one of the most biocompatible polymers suitable for FDM, while hydroxyapatite (HA) could improve the bioactivity of scaffold due to its chemical composition. Therefore, the combination of PLA/HA can create composite filaments adequate for FDM and with high osteoconductive and osteointegration potentials. In this work, we proposed a different approache to improve the potential bioactivity of 3D printed scaffolds for bone tissue engineering by increasing the HA loading (20-30%) in the PLA composite filaments. Two routes were investigated regarding the use of solvents in the filament production. To assess the suitability of the FDM-3D printing process, and the influence of the HA content on the polymer matrix, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) were performed. The HA phase content of the composite filaments agreed with the initial composite proportions. The wettability of the 3D printed scaffolds was also increased. It was shown a greener route for obtaining composite filaments that generate scaffolds with properties similar to those obtained by the solvent casting, with high HA content and great potential to be used as a bone graft.

Cellulose nanocrystals (CNCs) are unique and promising natural nanomaterials that can be extracted from native cellulose fibers by acid hydrolysis. In this study, we developed chemically modified CNC derivatives by covalent tethering of PEGylated biotin and perylenediimide (PDI)-based near-infrared organic dye and evaluated their suitability for labeling and imaging of different cell lines including J774A.1 macrophages, NIH-3T3 fibroblasts, HeLa adenocarcinoma cells, and primary murine dendritic cells. PDI-labeled CNCs showed a superior photostability compared to similar commercially available dyes under long periods of constant and high-intensity illumination. All CNC derivatives displayed excellent cytocompatibility toward all cell types and efficiently labeled cells in a dose-dependent manner. Moreover, CNCs were effectively internalized and localized in the cytoplasm around perinuclear areas. Thus, our findings demonstrate the suitability of these new CNC derivatives for labeling, imaging, and long-time tracking of a variety of cell lines and primary cells.

Injured bone tissues can be healed with bone grafts, but this procedure may cause intense pain to the patient. A slow and localized delivery of nonsteroidal anti-inflammatory drugs (NSAIDs) could help to reduce the pain without affecting bone regeneration. The objective of the present study was to use [Mg-Al]-layered double hydroxide (LDH) as a matrix for controlled release of sodium naproxen (NAP). This system could be applied in biomaterial formulations (such as bone grafts) to achieve a local delivery of naproxen. [Mg-Al]-LDH successfully incorporated up to 80% (w/w) of naproxen by the structural reconstruction route, with the [Mg-Al]-LDH interlayer space increasing by 0.55 nm, corresponding to the drug molecule size. The evaluation of the naproxen release kinetics showed that 40% of the drug was delivered over 48 h in aqueous medium (pH 7.4 ± 0.1), indicating the potential of [Mg-Al]-LDH/NAP for local release of naproxen at adequate concentrations. Kinetic modeling showed that the naproxen release process was closely related to the Higuchi model, which considers the drug release as a diffusional process based on Fick’s law. The chemical stability of NAP after the release tests was verified by 1H NMR. The [Mg-Al]-LDH/NAP also exhibited low cytotoxicity toward fibroblast cells (L929 cell line), without modifications in their morphology and adhesion capacity. These results describe a suitable approach for preparing efficient systems for local delivery of nonsteroidal anti-inflammatory drugs for biomedical applications.

Nanocellulosic materials, either as cellulose nanofibrils (CNF) or cellulose nanocrystals (CNC), have a wide range of potential applications in different industrial sectors, due to their renewable ...

Made available in DSpace on 2022-04-08T11:02:03Z (GMT). No. of bitstreams: 1 P-Electrospun-polylactic-acid-nanofibers-loaded-with-silver-....pdf: 2312409 bytes, checksum: 31e2f3d9af7ba66efcdd1a834713a40e (MD5) Previous issue date: 2020

The application of green process engineering strategies to obtain high-value, eco-friendly, and biodegradable materials from residual lignocellulosic biomass can contribute to the sustainability of...

Over the last few decades, there has been an increasing interest in ammonia gas detection for a wide range of applications, including food and environmental sectors and medical diagnostics. Herein, a useful NH3 gas sensor based on a hybrid nanocomposite (NFI-rGO) combining In2O3 ceramic nanofibers (NFI) and reduced graphene oxide (rGO) is proposed. The NFI was obtained by electrospinning technique followed by calcination treatment. The hybrid nanostructure was achieved by covering of the as-prepared NFI with rGO. The structure, surface morphology, and elementary composition of the NFI-rGO were characterized by X-ray diffraction, X-ray photo-electron spectroscopy, scanning and transmission electron microscopies. The ammonia sensing performance of the NFI-rGO was investigated at room temperature by exposing the sensor to a variable gas concentration in the range from 1 up to 60 ppm. The hybrid nanocomposite exhibited superior electrical sensing properties and selectivity when compared with each individual material as sensing layer, indicating the synergistic effect between NFI and rGO. The NFI-rGO nanocomposite sensor showed a fast response with sensitivity 10 times higher than the individual NFI and rGO, a low detection limit of 44 ppb and an outstanding selectivity to NH3 against other nitrogenated compounds and organic solvents. The enhanced sensing performance could be ascribed to the p-n heterojunction and the synergistic effect between the nanofibrous structure and the 2D rGO sheets, paving the way for the development of novel room temperature ammonia sensors employing hybrid nanocomposites.

Renewable cellulose substrates with submicron- and nanoscale structures have revived interest in paper electronics. However, the processes behind their production are still complex and time- and energy-consuming. Besides, the weak electrolytic properties of cellulose with submicron- and nanoscale structures have hindered its application in transistors and integrated circuits with low-voltage operation. Here, we report a simple, low-cost approach to produce flexible ionic conductive cellulose mats using solution blow spinning, which are used both as dielectric interstrate and substrate in low-voltage devices. The electrochemical properties of the cellulose mats are tuned through infiltration with alkali hydroxides (LiOH, NaOH, or KOH), enabling their application as dielectric and substrate in flexible, low-voltage, oxide-based field-effect transistors and pencil-drawn resistor-loaded inverters. The transistors exhibit good transistor performances under operation voltage below 2.5 V, and their electrical performance is strictly related to the type of alkali ionic specie incorporated. Devices fabricated on K+-infiltrated cellulose mats present the best characteristics, indicating pure capacitive charging of the semiconductor. The pencil-drawn load resistor inverter presents good dynamic performance. These findings may pave the way for a new generation of low-power, wearable electronics, enabling concepts such as the "Internet of Things".

Bisphenol A (BPA) is an endocrine-disrupting chemical (EDC) employed in industrial processes that causes adverse effects on the environment and human health. Sensitive and inexpensive methods to detect BPA are therefore needed. In this paper, we describe an electrochemical biosensor for detecting low levels of BPA using polymeric electrospun nanofibers of polyamide 6 (PA6) and poly(allylamine hydrochloride) (PAH) decorated with gold nanoparticles (AuNPs), namely, PA6/PAH@AuNPs, which were deposited onto a fluorine-doped tin oxide (FTO) substrate. The hybrid layer was excellent for the immobilization of tyrosinase (Tyr), which allowed an amperometric detection of BPA with a limit of detection of 0.011 &mu, M in the concentration range from 0.05 to 20 &mu, M. Detection was also possible in real water samples with recoveries in the range of 92&ndash, 105%. The improved sensing performance is attributed to the combined effect of the large surface area and porosity of PA6/PAH nanofibers, the catalytic activity of AuNPs, and oxidoreductase ability of Tyr. These results provide a route for novel biosensing architectures to monitor BPA and other EDCs in water resources.

The use of ultraviolet (UV) and blue irradiation to sterilize surfaces is well established, but commercial applications would be enhanced if the light source is replaced with ambient light. In this paper, it is shown that nanofibers can be explored as an alternative methodology to UV and blue irradiation for bacterial inactivation. It is demonstrated that this is indeed possible using spun nanofibers of poly[lactic-co-(glycolic acid)] (PLGA). This work shows that PLGA spun scaffolds can promote photoinactivation of Staphylococcus aureus and Escherichia coli bacteria with ambient light or with laser irradiation at 630 nm. With the optimized scaffold composition of PLGA85:15 nanofibers, the minimum intensity required to kill the bacteria is much lower than in antimicrobial blue light applications. The enhanced effect introduced by PLGA scaffolds is due to their nanofiber structures since PLGA spun nanofibers were able to inactivate both S. aureus and E. coli bacteria, but cast films had no effect. These findings pave the way for an entirely different method to sterilize surfaces, which is less costly and environmentally friendly than current procedures. In addition, the scaffolds could also be used in cancer treatment with fewer side effects since photosensitizers are not required.

Made available in DSpace on 2021-06-25T10:29:21Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 BACKGROUND: Cut flowers require proper postharvest stem hydration to prolong vase life. Nano-sized chitosan is an effective antimicrobial agent that has several potential agricultural applications. In this study, we compared the efficacies of solutions containing chitosan nanoparticles, regular chitosan particles, citric acid, and distilled and tap water controls in treating cut gerbera inflorescences during postharvest storage. Relative water uptake (RWU), transpiration rate (TR), water balance (WB), ligule color, solution pH, stem bending, stem-end blockage, and counts of bacteria, mold and yeast were investigated. RESULTS: The solution containing chitosan nanoparticles prevented stem bending, enabled higher RWU (41.8 g kg−1 day−1), established a suitable WB, and controlled microbial growth more efficiently than the other solutions. The chitosan nanoparticle solution strongly inhibited molds and yeasts. CONCLUSION: The results of this study demonstrated that nano-chitosan is a promising postharvest preservative for cut gerbera inflorescences. © 2021 Society of Chemical Industry (SCI). Departamento de Produção Vegetal Universidade de São Paulo (USP/ESALQ) Pesquisa e Desenvolvimento Embrapa Hortaliças Ciências Biológicas Universidade Federal de São Carlos (UFSCar) Departamento de Física e Química Universidade Estadual Paulista (UNESP) Faculdade de Engenharia Pesquisa e Desenvolvimento Embrapa Instrumentação Departamento de Física e Química Universidade Estadual Paulista (UNESP) Faculdade de Engenharia

Made available in DSpace on 2020-12-10T20:06:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-10-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Ministry of Science, Technology, and Innovation (MCTI/SISNANO) This contribution falls within the context of sustainable functional materials. We report on the production of fruit leathers based chiefly on peach pulp, but combined with hydroxypropyl methylcellulose (HPMC) as binding agent and cellulose micro/nanofibrils (CMNF) as fillers. Increased permeability to moisture (from 0.9 to 5.6 g mm kPa(-1) h(-1)m(-2)) and extensibility (from 10 to 17%) but reduced mechanical resistance (67-2 MPa) and stiffness (1.8 GPa-18 MPa) evidenced the plasticizing effect of peach pulp in HPMC matrix, which was reinforced by CMNF. A ternary mixture design allowed building response surfaces and optimizing leather composition. The laboratory-scale leather production via bench casting was extended to a pilot-scale through continuous casting. The effect of scaling up on the nutritional and sensory features of the peach leather was also depicted. The herein established composition-processing-property correlations are useful to support the large-scale production of peach leather towards applications both as packaging materials and as nutritional leathers. Embrapa Instrumentat, Nanotechnol Natl Lab Agr LNNA, Rua 15 Novembro 1452, BR-13560979 Sao Carlos, SP, Brazil Univ Fed Sao Carlos, Dept Chem, PPGQ, Rod Washington Luis,Km 235, BR-13565905 Sao Carlos, SP, Brazil Univ Fed Sao Carlos, Dept Mat Engn, Rod Washington Luis,Km 235, BR-13565905 Sao Carlos, SP, Brazil Sao Paulo State Univ, Dept Phys & Chem, FEIS, Av Brasil 56, BR-15385000 Ilha Solteira, SP, Brazil Sao Paulo State Univ, Dept Phys & Chem, FEIS, Av Brasil 56, BR-15385000 Ilha Solteira, SP, Brazil FAPESP: 2013/14366-7 FAPESP: 2014/23098-9 FAPESP: 2019/06170-1 CNPq: 303796/2014-6 CNPq: 312530/2018-8 CNPq: 800629/2016-7 CAPES: 33001014005D-6 CAPES: 88882.332747/2019-01 Ministry of Science, Technology, and Innovation (MCTI/SISNANO): 402287/2013-4

We report a paper-based electrochemical immunosensor made with sustainable materials to detect aflatoxin B1 (AFB1), a highly toxic, carcinogenic mycotoxin found in food. The immunosensor was prepared with a waterproof paper substrate and low-cost graphite-based conductive ink through a simple cut-printing method. The working electrode was functionalized with a drop-cast film of multiwalled carbon nanotubes (MWCNT)/chitosan on which a layer of anti-AFB1 monoclonal antibodies was immobilized covalently. The architecture of the immunosensor was confirmed with polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS) and electrochemical impedance spectroscopy (EIS), including the effective immobilization of the active layer of anti-AFB1. With EIS as the principle of detection, the immunosensor could detect AFB1 in the range from 1 to 30 ng&middot, mL&minus, 1, and detection limit of 0.62 ng&middot, 1. This sensitivity is sufficient to detect AFB1 in food according to regulatory agencies. The immunosensor exhibited good repeatability, reproducibility, stability, and selectivity in experiments with a possible interferent. Furthermore, detection of AFB1 in maize flour samples yielded recovery of 97&ndash, 99%, in a demonstration of the possible use of the paper-based immunosensor to detect AFB1 using extraction solutions from food samples.

Detection of pathogenic microorganisms is essential for food quality control and diagnosis of various diseases, which is currently performed with high-cost, sophisticated methods. In this paper, we report on a low-cost detection method based on impedance spectroscopy to detect Staphylococcus aureus (S. aureus). The immunosensors were made with microfluidic devices made of interdigitated electrodes coated with layer-by-layer (LbL) films of chitosan and chondroitin sulfate, on which a layer of anti-S. aureus antibodies was adsorbed. The limit of detection was 2.83 CFU mL−1 with a limit of quantification of 9.42 CFU mL−1 for immunosensors with 10-bilayer LbL films. This level of sensitivity is sufficient to detect traces of bacteria that cause mastitis in milk, which we have confirmed by distinguishing milk samples containing various concentrations of S. aureus from pure milk and milk contaminated with Escherichia coli (E. coli) and Salmonella. Distinction of these samples was made possible by projecting the electrical impedance data with the interactive document mapping (IDMAP) technique. The high sensitivity and selectivity are attributed to the highly specific interaction with anti-S. aureus antibodies captured with polarization-modulated reflection absorption spectroscopy (PM-IRRAS), with adsorption on the antibodies explained with the Langmuir–Freundlich model. Since these immunosensors are stable for up to 25 days and detection measurements can be made within minutes, the methodology proposed is promising for monitoring S. aureus contamination in the food industry and hospitals, and in detecting bovine mastitis., This work was supported by São Paulo Research Foundation (FAPESP) (Grants # 2018/18953-8 and 2018/22214-6, CNPq, CAPES (Grant # 88887364257/2019-00), SISNANO (MCTI) and Rede AgroNano for the financial support. The authors also are grateful to CNPEM researchers Maria Helena Piazzetta and Angelo Gobbi for their assistance in electrode fabrication.

The development of nanofibrous membranes with tunable wettability, degradation, and biocompatibility is highly keen for biomedical applications, including drug delivery and wound dressing. In this study, biocompatible and biodegradable nanofibrous membranes with antioxidant properties were successfully prepared by the electrospinning technique. The membranes were developed using polylactic acid (PLA) and polyethylene oxide (PEO) as the matrix, with the addition of grape seed extract (GSE), a rich source of natural antioxidants. The nanofibrous membranes were thoroughly characterized both from the materials and from the biocompatibility point of view. PLA and PLA/PEO nanofibers showed high encapsulation efficiency, close to 90%, while the encapsulated GSE retained its antioxidant capacity in the membranes. In vitro release studies showed that GSE diffuses from PLA/GSE and PLA/PEO/GSE membranes in a Fickian diffusion manner, whose experimental data were well fitted using the Korsmeyer-Peppas model. Furthermore, a higher controlled release of GSE was observed for the PLA/PEO/GSE membrane. Moreover, culturing experiments with human foreskin fibroblast (HFF1) cells demonstrated that all samples are biocompatible and showed that the GSE-loaded PLA/PEO nanofibrous membranes support better cell attachment and proliferation compared to the PLA/GSE nanofibrous membranes, owing to the superior hydrophilicity. In summary, the results suggested that the GSE-loaded membranes are a promising topical drug delivery system and have a great potential for wound dressing applications.

New materials can be developed using a known compound with enhanced properties modifying and controlling its microstructure, morphology, and density of defects. In this work, a new material was produced by the addition of ionic liquid (IL) to the poly(o-methoxyaniline) (POMA) conductive polymer, in the form of esmeraldine salt. The polymer impregnated with IL was tested as an electrode for use in supercapacitors. The results show that the charge storage properties of the materials are dependent on the length of the alquil substituent of imidazolium ring of ionic liquid cation. The best results, obtained by the addition of 1-butyl-3-methylimidazolium triflate IL to the polymer, improved electrical charge storage and electrochemical stability, making the material a promising electrode for supercapacitor devices. This compound has specific capacitance of 205 F/g, five times larger than pure POMA and was stable for 3000 cycles of charge/discharge experiments carried out at 1.0 A/g.

Over the last few years, there has been a great interest in the production of cellulose nanofiber films. However, conventional casting and film with only one kind of nanofiber may give rise to brittle material. Furthermore, films formed by the mixture of cellulose nanocrystal (CNC) and cellulose nanofibril (CNF) by continuous casting have not been reported. In this way, this study aims to investigate the optical, thermal, mechanical, and physical properties of the mixture of CNC and CNF films obtained by continuous casting from curaua and eucalyptus fibers at the proportions of 0/100, 25/75, 50/50, 75/25, and 100/0 (% w/w). After continuous casting, neat CNC and neat CNF are cleared oriented, causing anisotropic mechanical properties. On the other hand, the mixture of CNC and CNF made the films mechanically more isotropic, even though some degree of orientation of the fibers. The films with a mixture of CNC/CNF 25/75 (% w/w) were more thermally stable. The addition of CNC in CNF films decreased their opacity. Thus, the type of nanofibers, the cellulose source, the process, and the mixture of CNC/CNF affect the properties of the films significantly. CNC/CNF blend films obtained by continuous casting.

Alginate (ALG) is an abundant, biocompatible, regenerative, and nontoxic polysaccharide that has potential applications in tissue engineering. Silver sulfadiazine (SDZ) is a topical antibiotic used to control bacterial infection in burns. Aiming to combine the intrinsic alginate characteristics and silver sulfadiazine antimicrobial properties, hydrotalcite ([Mg-Al]-LDH) was used as a host matrix to obtain a system efficient in delivering SDZ from alginate films. SDZ was successfully intercalated in [Mg-Al]-LDH through structural reconstruction. Different solutions were prepared using sodium alginate at 10 wt%, glycerol at 10 wt% as a plasticizer and [Mg-Al]-LDH and [Mg-Al]-LDH/SDZ as fillers at 1 wt% and 5 wt%. Films were obtained by continuous casting and further characterized for their microstructural, mechanical, water barrier and antimicrobial properties. Cytotoxicity tests were also performed on fibroblasts cells. The incorporation of [Mg-Al]-LDH and [Mg-Al]-LDH/SDZ presented neither negative nor positive effects on the mechanical properties and morphology of the alginate films. Moreover, samples containing SDZ exhibited inhibitory activity against S. aureus, E. coli, and S. enterica. The addition of [Mg-Al]-LDH/SDZ even at the highest concentration did not afford a very significant cytotoxicity to the alginate-[Mg-Al]-LDH/SDZ films. These results describe a suitable approach for preparing innovative active wound dressings integrated to efficient drug delivery.

Composites of thermoplastic cassava starch (TPS) and oil palm mesocarp fibers (OPMF) were prepared using a screw extrusion rheometer. Two types of OPMF were used: raw and alkaline treated oil palm fibers. TPS composites using raw fiber showed an improvement of 193% in the elastic modulus and 153% for maximum stress, while the elongation at break was kept constant when compared to the neat TPS matrix. The high improvement in the mechanical and thermal properties of the TPS matrix by the raw fiber is due to the presence of silica, which influences the interaction of the matrix and OPMF fibers. The present work shows that TPS composites with 10 wt% raw fiber have greater mechanical properties than higher OPMF raw fiber content or alkaline treated fibers and provides the use of OPMF residue to produce an eco-friendly composite for various applications.

This paper reports on a study of highly filled composites of polypropylene (PP) and 75 and 85% by weight of oil palm mesocarp fiber (OPF) with and without coupling agent, maleic anhydride-grafted poly (styrene-ethylene/butadiene styrene) (SEBS-MA) and a maleated polypropylene (MAPP). Composites were prepared using a thermokinetic mixer for blending followed by hot pressing. The thermal and mechanical behavior of these composites was investigated by flexural and impact testing and scanning electron microscopy (SEM). Dynamic mechanical analysis (DMA) was also used to study the properties. The MAPP improve the flexural modulus and flexural strength of the composites with 75 and 85wt% of oil palm fiber while SEBS-MA improved the impact strength of the composites. By SEM it was possible to observe some voids, pull out and debonding in the polypropylene, and allowing the observation of level of adhesion between the fiber and matrix. DMTA showed a decrease in storage modulus when high amounts of fiber we...

Bio-based chitosan/pectin blend films were prepared by solution casting and fully characterized in terms of their viscoelastic, thermo-mechanical and water affinity properties. Dynamic light scattering and rheological analyses served as a probe that polyelectrolyte complexes were formed through COO-/NH3+ ionic cross-linking, changing the chitosan/pectin solutions from Newtonian to pseudoplastic gel-like systems. The highest degree of ionic cross-linking has been found at a specific mass ratio (chitosan/pectin 25/75) and solid-state data were obtained in detail using dynamic mechanical thermal analysis. Ionic cross-linking was determining on the physical properties of chitosan/pectin blends, which was demonstrated by the thermo-mechanical spectra, high water contact angle and tensile strength of films. The specific thermo-mechanical properties of the chitosan/pectin films can be specifically modulated according to the chitosan/pectin mass ratio to ensure successfully applications in medicine, drug delivery, agricultural and food coatings.

We herein report the production of environmentally inspired all-cellulose composites in response to the ever-growing concern on the extensive usage of nonbiodegradable materials derived from nonrenewable resources. Hydroxypropyl methylcellulose (HPMC) was used as a film-forming matrix, while microcrystalline cellulose (MCC) was added as a reinforcement filler. Because the efficiency of fillers in transferring mechanical strength to polymer matrixes relies upon the dispersion level of the former within the latter, this contribution set out to improve the homogeneity of the composite films through a green, solvent-free approach. Indeed, as-received MCC actually decreased the tensile strength, Young’s modulus, and elongation at break of HPMC films in ca. 80%, 33%, and 90%, respectively. High-pressure microfluidization was demonstrated to break MCC particles down, not to play a role on cellulose crystallinity, and to expose surface groups and/or create mechanoradicals, as suggested by a combination of spectro...

Edible films made up of yellow passion fruit (YPF) rind and pectin as a matrix-forming agent are proposed as a means of valorizing passion fruit processing wastes. YPF films were produced at pilot-scale using continuous casting from aqueous formulations covering pectin/rind and water/pulp mass ratios of 100/0–0/100. YPF films were successfully obtained with systematic, tunable yellowish coloration and were achieved at an optimal temperature of 120 °C, leading to a drying time of 7 min and productivity of 0.03 m2 film min–1. YPF pulp is found to plasticize the pectin matrix of the films and thus can replace glycerol or other synthetic plasticizers. Films with the largest rind content (50 wt %) showed mechanical strength comparable to that of PVC cling film (9 vs 5 MPa). The biodegradable, renewable character of YPF films was demonstrated upon exposure to Escherichia coli, Staphylococcus aureus,, and Bradyrhizobium diazoefficiens, a nitrogen-fixing symbiotic bacterium.

Reliable analytical techniques to evaluate dairy products, including milk, are of outmost importance to ensure food safety against contaminants. Among possible substances employed as adulterants in milk, urea raises deep concern due to its harmful effects to consumer’s health. In the present study, a biosensing platform was developed to be applied in the electrochemical detection of urea. The sensing platform was fabricated using polymeric electrospun nanofibers of polyamide 6 (PA6) and polypyrrole (PPy) deposited onto fluorine doped tin oxide (FTO) electrodes, which were then modified with zinc oxide nanoparticles (ZnO). This material showed excellent properties for the immobilization of urease enzyme, conferring the FTO/PA6/PPy/ZnO/urease electrode high sensitivity for urea detection within the concentration range between 0.1 and 250 mg dL−1 with a limit of detection of 0.011 mg dL−1. The results achieved evidence the potential of electrospun nanofibers-based electrodes for applications in biosensors aiming at dairy products analysis.

An integrated biorefinery process is proposed here for the enzymatic production of cellulose nanofiber (CNF) and sugars in a stirred-tank reactor using eucalyptus cellulose pulp as feedstock. Process engineering variables required for scale-up such as impeller speed, power consumption, and rheological behavior were determined under different experimental conditions of solids loading (10 and 15% w/v) and enzyme dosage (5 and 10 mg/g). Based on the mixing time, an impeller speed rotation of 470 rpm was selected for provision of adequate homogenization of the medium. Total energy consumption ranged from 161 to 207 W h and showed that significantly lower power consumption could be achieved using 10 mg/g enzyme loading with 10% w/v solids. Evaluation of rheological behavior showed that transition to a turbulent flow regime during the enzymatic hydrolysis reaction resulted in a constant power number ranging from 2.06 to 2.51, which was also lower for 10 mg/g enzyme loading with 10% w/v solids. Integrated analysis of glucose released and CNF generated after enzymatic hydrolysis showed that glucose values varied from 42.0 to 90.6 g/L, corresponding to cellulose conversion ranging from 57.2 to 76.4%. These values are suitable for the microbial fermentation of sugars into biofuels, while leaving a useful amount of residual nanomaterial. The residual solids of the enzymatic reactions presented the characteristics of CNF, as shown by X-ray diffraction (XRD) analyses, with crystallinity index (CI) values of 72–81%, as well as by morphological analysis using field emission scanning electron microscopy (FEG-SEM), which revealed diameters in the range 18–31 nm, making this nanomaterial suitable for use in a wide range of industrial applications. The findings indicated the potential of using conventional stirred-tank reactors for enzymatic hydrolysis for the integrated production of CNF and glucose, hence contributing to the implementation of future large-scale biorefineries.

Made available in DSpace on 2018-11-26T17:45:04Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-04-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) In line with the increasing demand for sustainable packaging materials, this contribution aimed to investigate the film-forming properties of hydroxypropyl methylcellulose (HPMC) to correlate its chemical structure with film properties. The roles played by substitution degree (SD) and molecular weight (M-w) on the mechanical and water barrier properties of HPMC films were elucidated. Rheological, thermal, and structural experiments supported such correlations. SD was shown to markedly affect film affinity and barrier to moisture, glass transition, resistance, and extensibility, as hydroxyl substitution lessens the occurrence of polar groups. M-w affected mostly the rheological and mechanical properties of HPMC-based materials. Methocel (R) E4 M led to films featuring the greatest tensile strength (ca., 67 MPa), stiffness (ca., 1.8 GPa), and extensibility (ca., 17%) and the lowest permeability to water vapor (ca., 0.9 g mm kPa(-1) h(-1) m(-2)). These properties, which arise from its longer and less polar chains, are desirable for food packaging materials. Embrapa Instrumentat, Nanotechnol Natl Lab Agr LNNA, Rua 15 Novembro 1452, BR-13560970 Sao Carlos, SP, Brazil Univ Fed Sao Carlos, Dept Mat Engn, PPG CEM, Rodovia Washington Luis,Km 235, BR-13565905 Sao Carlos, SP, Brazil Univ Fed Sao Carlos, Dept Chem, PPGQ, Rodovia Washington Luis,Km 235, BR-13565905 Sao Carlos, SP, Brazil Sao Paulo State Univ, FEIS, Dept Phys & Chem, Av Brasil 56, BR-15385000 Ilha Solteira, SP, Brazil Sao Paulo State Univ, FEIS, Dept Phys & Chem, Av Brasil 56, BR-15385000 Ilha Solteira, SP, Brazil FAPESP: 2013/14366-7 FAPESP: 2014/23098-9 CNPq: 402287/2013-4

A wide variety of new green materials such as curaua leaf fibers (CLFs) has potential applications in nanotechnology. This study aims to investigate the thermomechanical properties and morphological structure of cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs) films obtained by continuous casting. The CNCs were obtained by acid hydrolysis and CNFs by mechanical shearing from bleached CLFs and eucalyptus pulp. The morphology after continuous casting resulted in oriented nanofibers, and as a consequence there was mechanical anisotropy. CNCs films showed the greatest values of tensile strength (36 ± 4 MPa) and the more effective fibrillation provided better mechanical strength of eucalyptus CNFs films than curaua CNFs films. Sulfur groups and mechanical shear degradation affected the stability of CNCs and CNFs films, respectively. Thus, the type of nanostructure, the way they interact to each other, the cellulose source and the process interfere significantly on the properties of the films.

Cassava starch films reinforced with cellulose nanowhiskers from oil palm mesocarp fibers were produced by casting. Nanowhiskers were obtained by sulphuric acid hydrolysis followed by microfluidization and incorporated in starch films at various loadings (1-10wt%). Morphological and mechanical characterizations showed that the reinforcing effect of oil palm cellulose nanowhiskers was significant at loadings of up to 6wt%, which was determined to be the nanowhiskers percolation threshold. Above this content, formation of agglomerates became more significant, causing a decrease in mechanical properties of starch bionanocomposites. Below percolation threshold, such as 2wt%, elongation at break increased by 70%, showing an effective reinforcing effect. Dynamic mechanical analyses revealed filler/matrix interactions through hydrogen bonding in bionanocomposites.

Thermoplastic starch properties depends of plastification process. The aim of this study was to analyze the effect of concentration of glycerol and water on plastification, glass transition temperature (Tg) and tensile properties of thermoplastic waxy starch (TPWS). Formulations were extruded in the following concentrations of starch/glycerol/water: 70/30/0 (TPWS 0%); 70/25/5 (TPWS 5%); 70/20/10 (TPWS 10%) weight percentage. Crystalline peaks in WAXS diagrams and native grains present in SEM micrographs showed that the TPWS 0% and 5% were not sufficient to promote total plastification of the waxy starch, and TPWS 10% showed the higher starch plastification. Tg measurements by DMTA were 30 oC to TPWS 0%, 23 oC to TPWS 5% and 40 oC to TPWS 10%. These results showed that glycerol and water had effect plasticizer in TPWS 5% and antiplasticizer in TPWS 10%. Mechanical tensile results showed that higher tensile strength was observed in the systems with more effective starch plastification.

In the present study, oil palm mesocarp fibers (OPMF), an agroindustrial residue from the production of palm oil, were used to obtain cellulose nanowhiskers. They were obtained from bleaching of fibers, followed by hydrolysis using sulfuric acid and microfkuidization, to control the length of cellulose nanowhiskers and avoid a decrease in thermal stability with extended acid hydrolysis time. The results showed that the nanowhiskers obtained by acid hydrolysis for 105 min resulted in structures with an average length (L) of 117 ± 54 nm and diameter (D) of 10 ± 5 nm. After 105 min of acid hydrolysis, the suspension was dialyzed and the neutral suspension was subjected to microfku- idization. At this time the nanowhiskers presented the same dimensions, even with the fibrils disintegration of both amorphous and crystalline phases, during the microfkuidization. However, after microfkuidization, the sample presented a more stable suspension, but the crystallinity decreased. Increasing the hydrolysis time from 105 to 140 min, more sulfonated nanowhiskers were obtained, presenting lower thermal stability, but higher crystallinity than the microfkuidized sample. Furthermore, this study proved that it is possible to obtain cellulose nanowhiskers from oil palm mesocarp fibers, an agroindustrial residue from the palm oil production, helping to reduce the environmental impact of this waste, as well as providing the obtaining of a high value-added product.

The feasibility of integration of cellulosic ethanol production with the manufacture of cellulose nanofibers (CNF) and cellulose nanocrystals (CNC) was evaluated using eucalyptus cellulose pulp as feedstock and employing the biochemical route alone. For the enzymatic hydrolysis step, experimental central composite design (CCD) methodology was used as a tool to evaluate the effects of solids loading (SL) and enzymatic loading (EL) on glucose release and cellulose conversion. Glucose concentrations from 45 to 125 g/L were obtained after 24 h, with cellulose conversions from 35 to 96%. Validation of the statistical model was performed at SL of 20% and EL of 10 mg protein/g, which was defined by the desirability function as the optimum condition. The sugars released were used for the production of ethanol by Saccharomyces cerevisiae, resulting in 62.1 g/L ethanol after 8 h (yield of 95.5%). For all the CCD experimental conditions, the residual solids presented CNF characteristics. Moreover, the use of a new strategy with temperature reduction from 50 to 35°C after 24 h of enzymatic hydrolysis enabled CNC to be obtained after 144 h. The CNC showed a crystallinity index of 83%, length of 260 nm, diameter of 15 nm, and aspect ratio (L/D) of 15. These characteristics are suitable for many applications, such as reinforcement in polymeric materials and other lower volume higher value bio-based products. The findings indicate the viability of obtaining ethanol and CNC using the biochemical route exclusively, potentially contributing to the future implementation of forest biorefineries. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1085-1095, 2017.

Blends of zein and poly(vinyl alcohol) (PVAl) were processed in an internal mixer (150oC, 50 rpm) for 5-8 minutes. Glycerol and oleic acid were used as plasticizers. The mixtures obtained were then compression molded and further characterized by Fourier transform infrared spectroscopy (FTIR), water-absorption experiments, mechanical tests, and scanning electron microscopy (SEM). FTIR analysis indicated the existence of hydrogen bonding interactions between zein and PVAl. Tensile tests showed that the addition of PVAl increased the flexibility of the blends. The tensile strength ranged from 1.7 to 5.7 MPa, elongation at break ranged from 2.7 to 32% and Young’s modulus ranged from 433 to 7371 MPa. Water absorption at equilibrium decreased with increasing zein content, which favored a brittle behavior in the zein/PVAl. The blends were immiscible in the composition studied and the presence of voids indicated poor interfacial interaction between the polymers.

This paper reports on biosensors made with a matrix of polylactic acid (PLA) fibers, which are suitable for immobilization of the anti-p53 active layer for detection of p53 biomarker. The PLA fibers were produced with solution blow spinning, a method that is advantageous for its simplicity and possibility to tune the fiber properties. For the biosensors, the optimized time to deposit the fibers was 60 s, with which detection of p53 could be achieved with the limit of detection of 11 pg/mL using electrical impedance spectroscopy. This sensitivity is also sufficient to detect the p53 biomarker in patient samples, which was confirmed by distinguishing samples from cell lines with distinct p53 concentrations in a plot where the impedance spectra were visualized with the interactive document mapping (IDMAP) technique. The high sensitivity and selectivity of the biosensors may be attributed to the specific interaction between the active layer and p53 modeled with a Langmuir-Freundlich and Freundlich isotherms and inferred from the analysis of the vibrational bands at 1550, 1650 and 1757 cm−1 using polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS). The successful immobilization of the active layer is evidence that the approach based on solution blown spun fibers may be replicated to other types of biosensors., The authors are grateful to Brazilian National Council for Scientific and Technological Development (CNPq) (Grant #150985/2017-7, #113757/2018-2, #402287/2013-4 and 303796/2014-6), São Paulo Research Foundation (FAPESP) (Grant #2013/14262-7, #2017/18725-2 and #2018/18953-8), CAPES (001), INEO, and Barretos Cancer Hospital. The authors are also thanks to Maria Helena Piazzetta and Angelo Gobbi (LMF/LNNANO/CNPEM, Brazil) for their assistance in electrode fabrication.

In this work, the natural flower extracted dyes containing luteolin were prepared using three different specimens from daisy flowers family (Leucanthemum vulgare), namely yellow daisy, purple daisy and wine daisy, according to the color of its petals. Moreover, DSSCs were fabricated using nanosized titanium dioxide (TiO2) as an anode; for the photocathodes, two different specimens were used: i) graphite electrode and ii) platinum electrode. To recognize the light absorption behavior, the existence of anchoring groups and coloring components of the extracted dyes were determined using absorption spectroscopy. The surface roughness of the photoanodes and cathodes were examined using atomic force microscope (AFM). The photovoltaic performance and efficiency of assembled DSSCs were evaluated to realize the influence of TiO2 photoanodes on interaction of the Leucanthemum vulgare extracted dye molecules with graphite or platinum photocathodes. DSSCs fabricated with platinum cathode show higher conversion efficiency (η) of 0.6%, 0.4% and 0.8% for the yellow daisy, wine daisy and purple daisy, respectively. DSSCs sensitized with daisy wine dye showed highest open-circuit voltage (Voc) of 520 mV and efficiency of 0.79% and 0.88%, for the graphite and platinum cathodes, respectively. These results showed that the DSSCs, using daisy flowers extracts as efficient photosensitizers, are suitable for the fabrication of environmentally safe, inexpensive, clean and renewable energy.

Cellulose nanocrystals (CNC) were obtained from macauba and gravata fibers. Macauba (or Bocaiuva) is a palm tree found throughout most of Brazil and Gravata is an abundant kind of bromelia with 1&ndash, 2m long leaves, found in Brazilian Pantanal and Cerrado. The raw fibers of both fibers were mercerized with NaOH solutions and bleached, they were then submitted to acid hydrolysis using H2SO4 at 45 &deg, C, varying the hydrolysis time from 15 up to 75 min. The fibers were analyzed by X-ray diffraction (XRD), FTIR Spectroscopy, scanning electron microscopy (SEM) and thermal stability by thermogravimetric analysis (TG). XRD patterns did not present changes in the crystal structure of cellulose after mercerization, but it was observed a decrease of hemicellulose and lignin contents, and consequently an increase of cellulose content with the increase of NaOH solution concentration in the mercerization. After acid hydrolysis, the cellulose nanocrystals (CNC) were also analyzed by transmission electron microscopy (TEM) which showed an acicular or rod-like aspect and nanometric dimensions of CNC from both fibers, but the higher values of aspect ratio (L/D) were found on CNC obtained from gravata after 45 min of acid hydrolysis. The mercerization and subsequent bleaching of fibers influenced the crystallinity index and thermal stability of the resulting CNC, but their properties are mainly influenced by the hydrolysis time, i. e., there is an increase in crystallinity and thermal stability up to 45 min of hydrolysis, after this time, both properties decrease, probably due to the cellulose degradation by the sulfuric acid.

The presence of contaminants in water is a subject of paramount importance nowadays, which can make water improper to human consumption even when these contaminants are present at very low concentrations, causing health issues and economic losses. In this work, we evaluated the performance of nanocomposites based on nylon 6,6/chitosan electrospun nanofibers modified by cellulose nanowhiskers combined with functional materials like silver nanoparticles, gold nanoparticles, and reduced graphene oxide to be used as sensing layers of an electronic tongue (e-tongue) to detect Isoborneol. This compound, found in some plants and essential oils, is used as a natural repellent and also to produce many other chemicals. Additionally, its chemical structure is related to that of 2-methylisoborneol, a critical pollutant in aqueous media. The synergism between the nanomaterials combined with electrospun nanofibers could be verified by the enhancement of the charge transference ability. Additionally, electrical capacitance data measured with the impedimetric e-tongue were treated by Principal Component Analysis (PCA), and revealed the sensing system was able to discriminate samples contaminated with Isoborneol at nanomolar concentrations. Moreover, the electronic tongue system could detect Isoborneol in real water samples under different concentrations.

Nanotechnology has provided innovative solutions to guarantee sustainable energy and maintain a clean environment for the future. In this regard, 1D nanostructured materials, such as nanofibers, are very attractive, especially for the development of economic and environmentally friendly approaches for wastewater treatment. Recently, Solution Blow Spinning (SBS) has appeared as a powerful fiber forming technique with several advantages compared to the traditional electrospinning method. Herein, we present the fabrication of composite membranes using solution blow spun poly(methylmethacrylate) nanofibers wrapped with reduced graphene oxide (PMMA-rGO) to adsorb methylene blue (MB), which is a typical dye used in the printing and dyeing industry. The dye adsorption kinetics and isotherm follow the pseudo-second-order and the Langmuir models, respectively. The π–π stacking interactions were considered to be the major driving force for the spontaneous adsorption of MB and the maximum adsorption capacity was 698.51 mg g−1 according to Langmuir fitting. The developed nanocomposite shows great potential for decolorizing dyeing wastewater aimed at industrial and environmental remediation applications.

Poly(lactic acid) (PLA) is a biodegradable polymer that exhibits high elastic modulus, high mechanical strength, and feasible processability. However, high cost and fragility hinder the application of PLA in food packaging. Therefore, this study aimed to develop flexible PLA/acetate and PLA/chitosan films with improved thermal and mechanical properties without the addition of a plasticizer and additive to yield extruder compositions with melt temperatures above those of acetate and chitosan. PLA blends with 10, 20, and 30 wt% of chitosan or cellulose acetate were processed in a twin-screw extruder, and grain pellets were then pressed to form films. PLA/acetate films showed an increase of 30 °C in initial degradation temperature and an increase of 3.9 % in elongation at break. On the other hand, PLA/chitosan films showed improvements in mechanical properties as an increase of 4.7 % in elongation at break. PLA/chitosan film which presented the greatest increase in elongation at break proved to be the best candidate for application in packaging.

This paper reports on a study of highly filled composites of polypropylene (PP) and 75% by weight sugarcane bagasse fiber with and without alkali treatment and with and without coupling agent (SEBS-g-MA). Composites were prepared using a Rheomix600 mixer connected to a HAAKE torque rheometer. The thermal and mechanical behavior of these composites were investigated by thermogravimetry (TGA), differential Scanning Calorimetry (DSC), flexural tests, impact tests and scanning electron microscopy. Scanning electron microscopy (SEM) images taken from sugarcane bagasse fibers showed enhancements in the fiber's surface topography after the surface treatment process. The FTIR, TGA and SEM results for the fibers showed that the alkali treatment modified the fiber surface as well as the chemical composition. The impact test results showed a good potential of SEBS-g-MA as coupling agent and impact modifier in highly filled composites, increasing by more than 100% the impact strength of the composite as compared to those without the coupling agent. Scanning electron microscopy showed that addition of coupling agent improved the interfacial adhesion between the fibers and polypropylene.

The reuse of the solid residues generated in the production of second-generation (2G) ethanol to obtain high-value products is a potential strategy for improving the economic and environmental viability of the overall process. This study evaluated the feasibility of using the residual solids remaining after the enzymatic hydrolysis of sugarcane bagasse for the production of cellulose nanocrystals (CNC), a valuable bionanomaterial. To this end, sugarcane bagasse subjected to steam explosion (SEB) or liquid hot water (LHWB) pretreatment was hydrolysed using different loadings of a commercial cellulase cocktail. Samples of SEB and LHWB were hydrolysed enzymatically, resulting in glucose releases close to 40 g/L, which would be suitable for producing 2G ethanol by microbial fermentation. The solid residues after the enzymatic hydrolysis step presented cellulose contents of up to 54 %, indicating that a significant amount of recalcitrant crystalline cellulose remained available for subsequent use. These solid residues were purified and submitted to acid hydrolysis, resulting in the successful formation of CNC with crystallinity close to 80 %, lengths of 193–246 nm and diameters of 14–18 nm. The CNC produced presented morphology, dimensions, physical-chemical characteristics, thermal stability and crystallinity within the ranges reported for this type of material. Moreover, the enzyme loading or the type of hydrothermal pretreatment process employed here showed no significant effects on the CNC obtained, indicating that these variables could be flexibly adjusted according to specific interests.

Efficient use of the entire lignocellulosic biomass is important for biorefinery sustainability, especially considering the extraction of high value-added products, such as nanocellulosic materials. This work investigates the feasibility of using sugarcane straw as a feedstock to obtain lignocellulose nanocrystals (LCNCs). Together with bagasse, the straw is a residue from the processing of sugarcane in the ethanol/sugar mills, but its effective use remains to be further studied. An organosolv pretreatment process was first applied to the straw for partial removal of the lignin and hemicellulose contents (reductions of 72.2 and 62.1 %, respectively) and to increase the surface area (observed by scanning electron microscopy and atomic force microscopy). Acid hydrolysis carried out for different reaction times, with or without mechanical treatment, resulted in high yields of sugarcane straw LCNCs (40–64 % of the total mass). X-ray diffraction analyses showed that the crystallinity of the LCNCs increased from 65 to 80 %, with an estimated average elementary crystallite size of 3.3 nm. The aspect ratios of the LCNCs were determined by AFM and ranged from 18.0–30.1. The onset of thermal degradation of the LCNCs occurred between 145 and 191 °C. The findings demonstrated the effective extraction of cellulose nanocrystals with residual lignin from sugarcane straw, opening the possibility of obtaining high value-added nanomaterials and contributing to the sustainability of future lignocellulosic biomass biorefineries.

Miniaturized and inexpensive sensing platforms remains an important goal for the field-deployable monitoring of toxic gases. In this work, we report a disposable ethanol sensor based on nanochitin-composite containing chitin nanowhiskers/zinc oxide nanoparticles/polyaniline (ChitNW-ZnO/PANI) produced via solution casting method. The as-prepared material was fully characterized by transmission electron microscopy, atomic force microscopy, contact angle measurements, mechanical tests, thermogravimetric analysis and X-ray diffraction, confirming its successful preparation and revealing its morphology, microstructure and composition. Such nanocomposite showed enhanced ethanol sensing performance at room temperature, in which quantitative analysis was obtained in the range 20–100 ppm with a detection limit of 17 ppm (S/N = 3). We further validated that common potential interfering agents were not misidentified with ethanol. The development of such a unique nanochitin-based composite as a disposable sensor is a great step ahead in flexible and wearable electronics having potential applications in different fields such as biomedical and biotechnological engineering, security and internet of things (IoT).