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The ever-growing environmental concerns over the unrestricted fossil sources exploitation for non-biodegradable materials production has stimulated research on alternative renewable resources. The pectin films (HDM) were incorporated in different concentrations of spent coffee grounds (SCG) (5-20% w/w HDM) aiming at developing biodegradable films and the use of an underutilized resource. The films were obtained by continuous casting. The chemical composition, morphology, thermal stability, barrier and mechanical properties (traction and puncture), and functional groups were investigated. Overall, SCG showed sound dispersibility and good interaction with the polymer matrix. The addition of SCG resulted in important pectin-based film properties changes, allowing an increase in color and thermal stability. SCG incorporation significantly improved the water vapor permeability rate improving or at least preserving the physicochemical properties.

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.

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.

Efforts have been made on the development of new modified electrodes to be used in the fast determination of neurotransmitters, either in commercial drugs or in biological samples. Determination of dopamine (DA), for example, is of great importance since the lack of this neurotransmitter is related to many neurological disorders, including Parkinson’s and Alzheimer’s diseases. In this paper, we present a detailed electrochemical characterization, as well as DA detection studies of paste electrodes incorporating carbon materials in different allotropic forms, including carbon black modified with intrinsically conducting polymers (Eeonomers®), pristine carbon black, graphite, and carbon nanotubes. Emphasis is put on the smaller particle size and larger specific surface area of CB Eeonomers® materials, which led to an improved electroanalytical performance for the developed devices. The electrodes fabricated with Eeonomers® modified with polyaniline exhibited the higher current response towards DA detection, in addition to the ability of distinguishing DA from its natural interferent, ascorbic acid. Furthermore, a central composite design was used to investigate the influence of pH and electrode composition (proportion of Eeonomers®) on the electrochemical sensing of DA. A greater sensitivity was achieved for 50:50 (w/w) KP20/KPy20 electrode at pH 7.0. The optimized devices showed to be promising tools to perform quick, cheap and sensitive detection of this neurotransmitter in bioanalytical systems.

We report on gelatin films incorporating rosin-grafted cellulose nanocrystals (r-CNCs), which fulfill the most relevant requirements for antimicrobial packaging applications. Transparent gelatin/r-CNCs bionanocomposite films (0.5–6 wt% r-CNCs) were obtained by solution casting and displayed high UV-barrier properties, which were superior to the most used plastic packaging films. The gelatin/r-CNCs films exhibited a moderate water vapor permeability (0.09 g mm/m2 h kPa), and high tensile strength (40 MPa) and Young's modulus (1.9 GPa). The r-CNCs were more efficient in improving the optical, water vapor barrier and tensile properties of gelatin films than conventional CNCs. Grafting of rosin on CNCs resulted in an antimicrobial nanocellulose that inhibited the growth of Staphylococcus aureus and Escherichia coli. The antibacterial properties of r-CNCs were sustained in the gelatin films, as demonstrated by agar diffusion tests and proof-of-principle experiments involving cheese storage. Overall, the incorporation of r-CNCs as active fillers in gelatin films is a suitable approach for producing novel eco-friendly, antimicrobial packaging materials., This research was made possible thanks to the facilities of the Laboratory of Pulp and Paper 479 Science and Graphic Arts (LGP2) that is part of the LabEx Tec 21 (Investissements d'Avenir - grant 480 agreement n°ANR-11-LABX-0030) and of PolyNat Carnot Institute (Investissements d'Avenir - 481 grant agreement n° ANR-16-CARN-0025- 0), and Plant Macromolecule Research Center 482 (CERMAV) for the support to this work. This study was financed in part by CNPq, SISNANO 26 483 (MCTI), FINEP, Embrapa AgroNano research network (Embrapa), Coordenação de 484 Aperfeiçoamento de Pessoal de Nível Superior - Brazil (CAPES) [Finance Code 001] and by the 485 São Paulo Research Foundation (FAPESP) [grant numbers 2016/03080-2, 2017/18725-2 and 486 2018/00278-2, 2018/10899-4, 2018/22214-6, 2018/18953-8]. We would like to thank Berthine 487 Khelifi , Cécile Sillard and Thierry Encinas from Grenoble Institute of Technology for their 488 expertise in providing SEM imaging, XPS and XRD analyses, respectively.

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.

The effectiveness of antibiotics toward resistant strains of bacteria has brought serious concerns related to human and animal health. Controlled drug release systems, especially those based on polymer and polymer-based nanostructures appears as a remarkable approach, once they can potentially improve the therapeutic outcomes toward bacterial infections, while requiring lower amounts of drugs. The current study was designed to investigate the incorporation and release profile of a drug loaded in biodegradable electrospun nanofibrous membranes, based on the drug-polymer interactions, as well as its ability to inhibit bacterial growth. For that purpose, nanofibrous membranes of Ecovio® (EC), a polymer blend composed by poly (lactic acid) (PLA)/poly (butylene adipate-co-terephthalate) (PBAT), loaded with different cloxacillin (CLOX) contents were successfully produced via electrospinning technique. Electrospun nanofibers of EC unloaded and loaded with drug presented smooth surface with a mean diameter close to 600 nm. The physical-chemical characterizations by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) confirmed the successful drug encapsulation achieved by electrospinning technique. In vitro studies revealed that the developed drug-loaded nanofibrous membrane was successful in inhibiting S. aureus growth. The cumulative release of drug from EC nanofibrous membranes containing 20% of CLOX was demonstrated to be pH dependent, where the antibiotic release rate was much faster for pH 7.3 than that for pH 5.5. In this way, the mechanism involved in the release could be either Fickian or non-Fickian depending on the pH environment. The simple and efficient strategy presented here to develop antimicrobial nanofibrous membrane make them promising for drug delivery carrier and wound dressing applications.

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.

Nanostructured metal oxide semiconductors (MOS) based chemoresistive sensors play an important role in designing handheld, portable and cost-effective sensing systems for the detection of various target analytes. Herein, one-dimensional ZnO-Co3O4 heterostructure nanofibers (NFZCo) were successfully fabricated via electrospinning technique followed by a high-temperature treatment. The heterostructured nanofibers were fully characterized by scanning and transmission electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy and X-ray photo-electron spectroscopy. Using poly (sodium 4-styrenesulfonate) (PSS), a strong anionic polyelectrolyte, to modify the NFZCo surface, a hybrid material (NFZCo-PSS) was prepared, which worked as a humidity sensor through a cost-effective approach. The humidity sensing properties of the hybrid nanomaterial were investigated by exposing it to a wide relative humidity range of 25–75%. The NFZCo-PSS modified electrode exhibited a fast and large response in terms of electrical resistance as the humidity was varied at room temperature. Moreover, the response time for the humidification process was determined as less than 5 s. In general, the sensing performance of the hybrid platform was greatly superior than that of pure NFZCo. Moreover, the humidity sensing mechanism was ascribed to the synergistic effect of the nanofibers morphology and PSS toward water molecules. This work highlights that the hybrid NFZCo-PSS nanofibers can be used as active sensing nanostructures for humidity sensors application.

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

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.

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.

Cellulose nanocrystals (CNCs)-reinforced gelatin (Gel) films are appealing candidates for biodegradable packaging. However, tailoring the physical properties of Gel/CNCs films by control of pH and film-forming drying temperature continues unstudied. Here, we described the influence of pH on the physical properties of Gel/CNCs films covering different CNCs contents. The interactions between CNCs and Gel were studied by assessing the ζ-potential of Gel/CNCs suspensions under acidic (pH 3), Gel isoelectric point (pI, pH 6) and alkaline (pH 8) conditions. pH 3 promotes the electrostatic attraction, while pH 8 favors the electrostatic repulsion in the Gel-CNCs pair, increasing the suspension viscosity in both cases. The addition of 0.5 wt% CNCs decreased the water vapor permeability (WVP) of the Gel/CNCs films by 68% under electrostatic attractive forces and by 39% at the gelatin pI. The addition of 5 wt% CNCs at pH 3 resulted in the formation of complex coacervates, which decreased the mechanical properties and increased the WVP of Gel/CNCs films. Increasing pH above the Gel pI remarkedly increased the gelatin renaturation as triple helices, which was found to be key for increasing by 152% and 56% the Young's modulus and tensile strength, respectively, of the Gel/CNCs films with 0.5 wt% CNCsFilm-forming drying temperatures had an inverse effect on the triple helix content, and, consequently, on the physical properties of the Gel/CNCs films. These findings denote that modulating pH, CNCs amount, and drying temperature is a suitable strategy for tailoring the properties of nanocellulose-reinforced gelatin films for an extended range of food packaging applications.

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.

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.

This study aims at assessing the potential use of cellulose pulp in MgO-water slurries with potential for precast composites. These systems for composites applications envisage encapsulating CO2 when exposed to fast carbonation. The effect of cellulose fibers was evaluated on samples after the drainage of MgO-cellulose-water slurries. Different cellulose mass fractions were added into MgO-water suspensions – up to 30 wt% – to study the MgO hydration during the first 96 h. Afterward, the carbonation of the hydrated products for 6 and 12 h was evaluated. The addition of cellulose, after hydration, increases the sample porosity, where Mg(OH)2 is the main crystalline phase and only minor traces of unreacted MgO are found. MgO-H2O systems after hydration do not present any binding capacity given the low density and high apparent porosity of the clusters. However, XRD and TG analyses show that exposing samples to a rich CO2 environment promotes the formation of nesquehonite (MgCO3·3H20), which significantly reduces the porosity induced by the cellulose hygroscopy. This reduction in porosity is greater for samples with cellulose fibers because of the greater content of nesquehonite produced in samples with cellulose. Besides, cellulose fibers are covered with nesquehonite nanocrystals after carbonation. By adding cellulose to water-MgO suspensions yields lighter products with promising potential for fiber-cement applications. Moreover, the addition of cellulose contributes to the encapsulation of CO2 in building materials through the Mg(OH)2 carbonation.

The objective of this study was to prepare pectin films (PEC) activated by copaiba oil (CP) nanoemulsions (NE). CP-NE were added to film-forming formulations based on pectin and then dried into films by continuous casting. Chemical, morphological, thermal, mechanical and antimicrobial properties were studied in addition to biodegradability by the respirometer test. In general, the nanoemulsions were suitably dispersed in the PEC matrix, both phases showing good interaction and compatibility. The nanoemulsions caused large changes in PEC, such as increased roughness with oil concentration, gradual reduction of the elastic modulus and tensile strength, increased elongation at break, and antimicrobial activity against S. aureus and E. coli. Another important observation was the maintenance of the biodegradation profile of the films after the addition of CP-NE. In conclusion, the active pectin film manufactured with CP emulsions showed great potential for active food packaging and is a promising alternative to reduce environmental impacts.

Polyurethanes have been widely used in a wide variety of applications that benefit our everyday life. However, in the present scenario, it is urgent to find solutions towards more sustainable polymeric systems that can be more biodegradable and less dependent on non-renewable feedstocks. The present work proposes a thorough structural investigation of polyurethane materials based on the use of two small eco-friendly reactants: glycerol and urea. The results with glycerol demonstrated a preferential reactivity of MDI with primary alcohol terminals, except when the diisocyanate was in excess, which resulted in crosslinking formation (shown in 13C NMR). Urea-based materials displayed superior thermal stability, associated with higher crystallinity and intermolecular forces, as observed in TGA, XRD, and FTIR. Overall, the structural characteristics support the potential of biodegradability of the studied polyurethanes and polyureas.

In this paper, series of novel nanocomposite hydrogels based on polyacrylamide (PAAm), carboxymethylcellulose (CMC) and nanoclay were synthesized. Hydrophilic, kinetic, spectroscopic and morphological properties were investigated as function of their constituents. Spectroscopic properties confirmed the obtaining of the nanocomposites. It was also observed that the nanocomposites have walls of pores with a more rugged morphology compared with the morphology of the hydrogel without clay, contributing to repel the water molecules. Besides, the results showed that the velocity and quantity of water uptake may be controlled by adjusting of matrix rigidity, i.e., nanoclay content into polymeric matrix. This behavior is required to future application in agriculture fields, specifically as carrier vehicle in controlled release of agrochemicals. Thus, these nanocomposites have technological application.

Ammonia (NH3) gas is a prominent air pollutant that is frequently found in industrial and livestock production environments. Due to the importance in controlling pollution and protecting public health, the development of new platforms for sensing NH3 at room temperature has attracted great attention. In this study, a sensitive NH3 gas device with enhanced selectivity is developed based on zinc oxide nanofibers (ZnO NFs) decorated with poly(styrene sulfonate) (PSS) and operated at room temperature. ZnO NFs were prepared by electrospinning followed by calcination at 500 °C for 3 h. The electrospun ZnO NFs are characterized to evaluate the properties of the as-prepared sensing materials. The loading of PSS to prepare ZnO NFs/PSS composite is also optimized based on the best sensing performance. Under the optimal composition, ZnO NFs/PSS displays rapid, reversible, and sensitive response upon NH3 exposure at room temperature. The device shows a dynamic linear range up to 100 ppm and a limit of detection of 3.22 ppm and enhanced selectivity toward NH3 in synthetic air, against NO2 and CO, compared to pure ZnO NFs. Additionally, a sensing mechanism is proposed to illustrate the sensing performance using ZnO NFs/PSS composite. Therefore, this study provides a simple methodology to design a sensitive platform for NH3 monitoring at room temperature.

Endocrine disruptor compounds (EDCs) are environmental pollutant chemicals that can affect the endocrine system of some organisms. Such compounds are excreted by humans and released into aquatic environments via sewage treatment plant. One example of EDC is 17α-ethinylestradiol (EE2), a synthetic estrogen widely used as oral contraceptive and considered a powerful estrogenic. Although there has been a deep concern about the EDC presence in surface and drinking waters, there are only a few works in the scientific literature regarding EE2 electrochemical detection. Here we present the development of a new nanostructured sensing platform aimed at the electrochemical detection of EE2. The platform was based on a fluorine doped tin oxide (FTO) electrode coated with nanostructured Layer-by-Layer (LbL) films of chitosan/multi-walled carbon nanotubes (Chi/CNTs). The physicochemical properties of the films were evaluated by atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR). Electrochemical characterization revealed a decrease in the film resistance as the number of bilayers increased from 1 to 3, as a direct consequence of the augment in the amount of conductive material (CNTs). Cyclic voltammetric measurements showed that the three bilayer electrode, namely FTO-(Chi/CNTs) 3 , are suitable to EE2 detection, through an irreversible and adsorption-controlled electrochemical oxidation process. Square Wave Voltammetry (SWV) yielded a linear response for EE2 detection in range from 0.05 to 20 μmol L − 1 , with a detection limit of 0.09 μmol L − 1 (S/N = 3). The sensor showed a good reproducibility with the relative standard deviation (RSD) equal to 3.2% and 6.6% to intra- and inter-electrode, respectively. Furthermore, the sensor platform showed to be suitable to EE2 selective electrochemical detection, with no significant interference from common interfering compounds. The concepts behind the EE2 electrochemical behavior can be potentially harnessed for designing new electrochemical sensors and biosensors with the architecture described here.

The controlled-release of natural plant oils such as linalool is of interest in therapeutics, cosmetics, and antimicrobial and larvicidal products. The present study reports the release characteristics of linalool encapsulated at three concentrations (10, 15 and 20 wt.%) in poly(lactic acid) nanofibrous membranes produced by electrospinning and solution blow spinning (SBS) as well as the effect of linalool on fiber morphology and structural properties. PLA nanofibrous membranes were characterized by Scanning Electron Microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and contact angle measurements. The average diameters of the electrospun and solution blow spun nanofibers were similar, ranging from 176 to 240 nm. Linalool behaved as a plasticizer to PLA decreasing the glass transition temperature (Tg), melting point (Tm) and crystallization temperature (TC) of PLA. Curves of the release of linalool at 35 °C were non-linear, showing a clear biphasic pattern consistent with one or more Fickian release components. The time required to release 50% of linalool (t1/2) decreased with increasing linalool concentration. The range in t1/2 values for SBS nanofibers was higher (291-1645s) than the t1/2 values for electrospun fibers (76-575s).

Cellulose, the main component of plant cell walls, is a biopolymer widely used for industrial applications, including, food, paper and textile fabrication. More recently, hybrid materials composed of cellulose nanostructures and metal nanoparticles have been applied in diverse areas such as medical and pharmaceutical applications. In this work, cellulose-silver nanoparticles (AgNPs) hybrid material was synthesized and the influence of cellulose, employed as a stabilizer agent, was investigated. Specifically, cellulose whiskers (CCW) were extracted from commercial cotton fibers by acid hydrolysis route, while the AgNPs were synthesized by reducing silver salt using sodium citrate and/or sodium borohydride in the presence of CCW. The synthesized AgNPs/CCW nanocomposites were characterized in terms of morphology, chemical composition, surface charge and antibacterial properties. The varied synthetic routes generated AgNPs with different morphological characteristics in terms of size, shape and coalescence. The particularity of each sample resulted in distinct behaviors for the tested bacteria. Syntheses employing CCW resulted in AgNPs/CCW nanocomposites with controlled morphology and improved antibacterial effects against E. coli (Gram-negative) and S. aureus (Gram-positive), indicating CCW as a promising compound to be used in the syntheses of silver and other metal nanoparticles with controlled morphology and antibacterial properties.

The use of nanomaterials as an electroactive medium has improved the performance of bio/chemical sensors, particularly when synergy is reached upon combining distinct materials. In this paper, we report on a novel architecture comprising electrospun polyamide 6/poly(allylamine hydrochloride) (PA6/PAH) nanofibers functionalized with multiwalled carbon nanotubes, used to detect the neurotransmitter dopamine (DA). Miscibility of PA6 and PAH was sufficient to form a single phase material, as indicated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), leading to nanofibers with no beads onto which the nanotubes could adsorb strongly. Differential pulse voltammetry was employed with indium tin oxide (ITO) electrodes coated with the functionalized nanofibers for the selective electrochemical detection of dopamine (DA), with no interference from uric acid (UA) and ascorbic acid (AA) that are normally present in biological fluids. The response was linear for a DA concentration range from 1 to 70 μmol L(-1), with detection limit of 0.15 μmol L(-1) (S/N = 3). The concepts behind the novel architecture to modify electrodes can be potentially harnessed in other electrochemical sensors and biosensors.

Edible films supplemented with active ingredients are promising for food packaging and preservation. Numerous plant essential oils present antimicrobial activity against pathogenic microorganisms, but their low solubility in water limits food-related applications. Emulsification is herein exploited as a means of improving the dispersion of such active substances in water, imparting increased functionality and reduced degradation. Lemongrass essential oil (LEO) was directly emulsified as dispersed phase into aqueous solutions of pectin, which was used together with Tween 80 as polymeric emulsifiers. LEO nano- and micro-sized droplets were added to film-forming formulations based on glycerol-plasticized cassava starch (TPS) and then dried into films by continuous casting. LEO contents in films relied upon microbiological assays to ensure antimicrobial activity. Films’ chemical composition, morphological, thermal, mechanical, and barrier properties, in addition to biodegradability in vegetal compost, were comprehensively studied. In general, emulsions were suitably dispersed within the TPS matrix, both phases showing good interaction and compatibility. Emulsification caused important changes in the TPS-based films, such as improved colorimetric attributes, thermal stability, barrier to moisture, and mechanical properties. Another key observation was the maintenance of the biodegradation profile in soil of TPS after the addition of LEO emulsions. Overall, the emulsification approach was successful in providing TPS films with multifunctionality by the supplementation of an active substance without negatively affecting its fundamental properties for food packaging applications.

Made available in DSpace on 2020-12-12T02:31:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-03-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) The demand for bioplastics from renewable sources for a range of emerging applications has been as extensive as the efforts to find greener routes for their isolation from nature. Surfing this wave, we report on the production of flexible, optically semi-transparent onion-only bioplastics through different all-aqueous film-forming procedures encompassing hydrothermal, grinding, washing, and/or sieving pre-solvent casting steps. The onion bioplastics were extensively characterized targeting correlations among chemical structure, film-forming protocol, and film properties. HPLC evidenced insoluble carbohydrates/polysaccharides in all samples, though at different contents (11–44%) depending on processing, but washing lixiviated all soluble carbohydrates – the presence of ca. 14% of the latter in unwashed samples provided their films with reduced glass transition temperature – from 73–83 to 13 °C, as indicated by DSC; elastic modulus and tensile strength – from 1.5–3.2 GPa to 47 MPa and from 7–21 to 3 MPa, respectively; increased elongation at break – from 0.7–1.6% to 22%; and decreased contact angle with water – from 39-70° to 22° (in comparison with washed samples). Additionally, SEM provided morphological aspects; thermogravimetry indicated thermal stability profile; FTIR led to hydrogen bond energy [kJ] and distance [Å] as well as total crystallinity index (0.43–0.96), lateral order index (0.8–3.2), and hydrogen bonding intensity (13–4.7); and XRD determined the index of crystallinity (21–49%). Finally, the hydrophilic/hydrophobic nature, water barrier, and moisture sorption of the bioplastics were determined. Altogether, we herein depict the production of novel bioplastics made up exclusively of onion and used a range of characterization techniques to come up with relevant structure-processing-property correlations. São Paulo State University (UNESP) Institute of Chemistry Nanotechnology National Laboratory for Agriculture (LNNA) Embrapa Instrumentation University of Araraquara (Uniara) Laboratory of Biopolymers and Biomaterials (BIOPOLMAT) Chalmers University of Technology Department of Chemistry and Chemical Engineering São Paulo State University (UNESP) Institute of Chemistry FAPESP: 2014/23098-9 FAPESP: 2016/15504-2

Colorimetric sensors developed by the solution blow spinning (SBS) technique have a rapid response to a variation in different physicochemical properties. In this study, polystyrene nanofibrous (PSNF) mats containing the bromothymol blue (BTB) indicator were obtained by SBS for the pH sensing of wine sample. The incorporation of the indicator did not promote changes in fiber diameter but led to the appearance of beads, allowing for the encapsulation of BTB. The halochromic property of BTB was retained in the PSNF material, and the migration tests showed that the indicator mats presented values below the maximum acceptable limit (10 mg dm&minus, 2) established by EU Commission Regulation No. 10/2011 for foods with an alcohol content up to 20%. The present study opens the possibility of applying nanostructured materials to innovative food packaging which, through nanosensory zones, change color as a function of the food pH.

A novel biodegradable polymer based on glycerol, succinic anhydride and maleic anhydride, poly(glycerol succinate-co-maleate), poly(GlySAMA), was synthesized by melt polycondensation and tested as a matrix for composites with nanocrystalline cellulose. This glycerol-based polymer is thermally stable as a consequence of its targeted cross-linked structure. To broaden its range of properties, it was specifically formulated with nanocrystalline cellulose (NCC) at concentrations of 1, 2 and 4 wt%, and showed improved mechanical properties with NCC. Specifically, the effect of reinforcement on mechanical properties, thermal stability, structure, and biodegradability was evaluated, respectively, by tensile tests and thermogravimetric analyses, X-ray diffraction and respirometry. The neat poly(GlySAMA) polymer proved flexible, exhibiting an elongation-to-break of 8.8 % while the addition of nanowhiskers (at 4 wt%) caused tensile strength and Young’s modulus to increase, 20 and 40 %, respectively. Stiffness improved without significantly decreasing thermal stability as measured by thermogravimetric analysis. Biodegradation tests indicated that all samples were degradable but NCC reduced the rate of biodegradation.

Electrospun fibers are explored as a new system for controlled drug delivery. Novel techniques capable of obtaining polymer nanofibers have been reported in the literature. They include solution blow spinning (SBS), which is a technique to produce polymer nanofibers in the same range as electrospinning, using pressurized gas instead of high voltage. The present study investigates release characteristics of diclofenac sodium encapsulated at three concentrations (5, 10, and 20% w/v) in poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) nanofibers made by electrospinning and SBS and determines the drug’s effect on fiber morphology and structural properties. PHBV nanofibers were characterized using scanning electronic microscopy, differential scanning calorimetry, and X-ray diffraction, and the release profile was examined via UV-Vis spectrophotometry. Both electrospinning and SBS encapsulated diclofenac sodium in PHBV membranes efficiently and effectively. The profile of thein vitrorelease of diclofenac sodium was dependent on drug concentration and temperature. The drug reduced crystallinity and increased flexibility.

In order to investigate the incorporation of tannin from barbatimao bark in zein nanofibers obtained by electrospinning, it was studied the effect of addition of different contents of tannin in the properties of zein nanostructured membranes and their relationship with fiber morphology. It was confirmed the interaction occurring between the tannin and zein by thermal and microscopy analysis. Addition of tannins increased the glass transition temperature of the nanofibers, suggesting higher energy input for processing for example. SEM micrographs provided evidence of a homogeneous structure for the nanostructured membranes. X-ray analysis showed the presence of zein crystals in the nanofibers. This ongoing research confirms the possibility of incorporation of barbatimao tannin in the production of bio-nanofibers that will be studied for multi-purpose applications.

In this work, thermoplastic starch (TPS)–clay bionanocomposites were obtained by an innovative methodology using a combination of methodologies commonly used in the composites and nanocomposites preparations. The main objectives or novelties were to confirm efficiency of the processing methodology by field emission gun scanning electron microscopy and investigate the effect of clay content on the spectroscopic, bulk and surface hydrophilic/hydrophobic properties of these bionanocomposites. Raman and FTIR spectroscopies confirmed the changes in the spectroscopic properties of the TPS bionanocomposites with the addition of the clay materials. Water absorption and contact angle measurements were also used to analyze the effect of the clay content on the hydrophilic properties of the TPS bionanocomposites. The results also showed that the addition of the cloisite-Na + clay increased the bulk and surface hydrophobicities of the TPS matrix, which may increase its industrial application, particularly in manufacturing of food containers.

In this work, we synthesized a novel series of hydrogels composed of polyacrylamide (PAAm), methylcellulose (MC), and calcic montmorillonite (MMt) appropriate for the controlled release of fertilizers, where the components presented a synergistic effect, giving very high fertilizer loading in their structure. The synthesized hydrogel was characterized in relation to morphological, hydrophilic, spectroscopic, structural, thermal, and kinetic properties. After those characterizations, the application potential was verified through sorption and desorption studies of a nitrogenated fertilizer, urea (CO(NH2)2). The swelling degree results showed that the clay loading considerably reduces the water absorption capability; however, the hydrolysis process favored the urea adsorption in the hydrogel nanocomposites, increasing the load content according to the increase of the clay mass. The FTIR spectra indicated that there was incorporation of the clay with the polymeric matrix of the hydrogel and that incorporation increased the water absorption speed (indicated by the kinetic constant k). By an X-ray diffraction technique, good nanodispersion (intercalation) and exfoliation of the clay platelets in the hydrogel matrix were observed. Furthermore, the presence of the montmorillonite in the hydrogel caused the system to liberate the nutrient in a more controlled manner than that with the neat hydrogel in different pH ranges. In conclusion, excellent results were obtained for the controlled desorption of urea, highlighting the hydrolyzed hydrogels containing 50% calcic montmorillonite. This system presented the best desorption results, releasing larger amounts of nutrient and almost 200 times slower than pure urea, i.e., without hydrogel. The total values of nutrients present in the system show that this material is potentially viable for application in agriculture as a nutrient carrier vehicle.

Rice husk are generated from the rice cultivation. Silica is the major inorganic constituent of the rice husk, and by carrying out an acid chemical treatment followed by the process of burning, it is possible to extract high-surface area amorphous silica. This paper reports the extraction and characterization of nanosilica from two types of rice husk, namely agulhinha and cateto, using milder acid solutions. Thermogravimetry was used to characterize the burning behavior and to determine the activation energies. FT-IR results showed a good peak correlation between the commercial silica and burnt rice husk residue. There were found both nano- and microparticles with a large particle size distribution. The results showed the potential of silica extraction from rice husk, and additionally exhibited lower levels of corrosion damage to the reactor that generated weak acid residues due to the use of milder acid solutions.

Grupo de Compositos e Nanocompositos Hibridos - GCNH Faculdade de Engenharia de Ilha Solteira UNESP - Univ. Estadual Paulista Departamento de Fisica e Quimica

Cutin is the biopolyester that protects the extracellular layer of terrestrial plants against dehydration and environmental stresses. In this work, cutin was extracted from tomato processing waste and cast into edible films having pectin as a binding agent. The influences of cutin/pectin ratio (50/50 and 25/75), film-forming suspension pH, and casting method on phase dispersion, water resistance and affinity, and thermal and mechanical properties of films were investigated. Dynamic light scattering and scanning electron microscopy revealed that cutin phase aggregation was reduced by simply increasing pH. The 50/50 films obtained by casting neutral-pH suspensions presented uniform cutin dispersion within the pectin matrix. Consequently, these films exhibited lower water uptake and solubility than their acidic counterparts. The cutin/pectin films developed here were shown to mimic tomato peel itself with respect to mechanical strength and thermal stability. Such behavior was found to be virtually independent of pH and casting method.

Cellulose nanocrystals (CNCs) were extracted from Eucalyptus kraft pulp by sulfuric acid hydrolysis, and esterified with maleic anhydride (CNCMA). The incorporation of sulfate ester groups on the cellulose surface resulted in higher stability of the nanoparticles in aqueous suspensions and lower thermal stability. Then, PLA/CNC and PLA/CNCMA nanocomposites were successfully obtained by solution blow spinning (SBS) using dimethyl carbonate (DMC) as solvent. CNC and CNCMA indicated to be acting both as nucleating agents or growth inhibitors of PLA crystal and tends to favor the formation of PLA crystals of higher stability. A fraction of the nanocrystals indicate to be exposed on the surface of the PLA fibers, since the hydrophilicity of the composite films increased significantly. Such composites may have potential application as filtering membranes or adsorbents.

This paper is an initial study of the implementation of two new enzymes, an endoglucanase and a concoction of hemicellulases and pectinases to obtain cellulosic nanoparticles. In this study, curaua and sugarcane bagasse were dewaxed and bleached prior to enzymatic action for 72 h at 50 °C, and then followed by sonication. The concentration between these two enzymes was varied, and for the concentrations and time of enzymatic treatment used, subsequent sonication was necessary for cellulose nanoparticle release. It was easier to extract cellulose nanofibers from sugarcane bagasse which resulted in nanoparticles without damage of cellulose chains. On the other hand, curaua fibers needed a higher concentration of enzymes and the nanofibers obtained displayed a decrease of crystallinity suggesting that the cellulose structure was compromized. For both fibers, cellulose nanocrystals (single crystals) and larger diameter nanofibers were attained after the sonication.

The properties of mixtures of poly(lactic acid) (PLA) and poly(ethylene oxide) (PEO) were studied in polymer solutions by dilute solution viscometry, and in-solution blow-spun nanofibers were studied by microscopy (scanning electron and transmission electron microscopy) and thermal and spectral analysis. Three mixtures of PLA and PEO (3:1, 1:1, and 1:3) were solution-blended in chloroform. Dilute solvent viscometry indicated that the 3:1 mixture of PLA and PEO had a higher miscibility coefficient value than the other mixtures. The neat polymers and mixtures were solution-blow-spun into nanofibers. The fiber diameters were smallest in the neat polymers. Transmission electron micrographs revealed a core/sheath structure for the sample mixtures. X-ray analysis indi- cated that the crystallinity was positively correlated with the PEO content. Fibers from the mixtures had contact angle measurements similar to those of the neat PEO. Fourier transform infrared and Raman spectroscopy of the mixtures indicated interactions between ester and ether groups, which were attributed to dipole-dipole interactions between the ester groups of PLA and the ether groups of PEO. V C 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 129: 3672-3681, 2013

Solution blow spinning (SBS) is a novel technology feasible to produce nanostructured polymeric membranes loaded with active agents. In the present study, nanofibrous mats of poly(lactic acid) (PLA) loaded with progesterone (P4) were produced by SBS at different P4 concentrations. The spun membranes were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Fourier-transform infrared spectroscopy (FTIR). The in vitro releasing of P4 was evaluated using high-performance liquid chromatography (HPLC). Interactions between progesterone and PLA were confirmed by rheological measurements of the PLA/P4 solutions and in the spun mats by microscopy (SEM), thermal (DSC) and spectral (FTIR) analyses. SEM micrographs provided evidences of a smooth and homogeneous structure for nanostructured membranes without progesterone crystals on fiber surface. FTIR spectroscopy indicated miscibility and interaction between the ester of PLA and the ketone groups of the P4 in the nanofibers. X-ray analysis indicated that the size of PLA crystallites increased with progesterone content. Finally, by in vitro release experiments it was possible to observe that the progesterone releasing follows nearly first-order kinetics, probably due to the diffusion of hormone into PLA nanofibers.

A disposable low cost and simple flow-cell electronic tongue for water analysis is described. A sensor array is used that is comprised of six interdigitated microelectrodes coated with nanofiber films of poly(lactic acid)/mutliwalled carbon nanotube (MWCNT) composites. Fiber films are deposited directly on the interdigitated electrodes surface by solution blow spinning. Fiber film thickness is varied by using different deposition times (1, 3, and 15 min). Analysis of scanning electron microscopy and transmission electron microscopy micrographs indicates that average fiber diameters are 400 nm for neat poly lactic acid (PLA) and 200 nm for the PLA/MWCNT composite. The MWCNT is poorly dispersed in the PLA fiber matrix and formed aggregates interspersed throughout the fiber length. There are also MWCNTs exposed or partially exposed at the fiber surface. Fiber films containing MWCNT (1%) give the highest dc conductivity values and the most linear I-V profiles at room temperature. Sensor arrays with thin fiber film coatings (1 min deposition time) provide the best result for discriminating potable water samples using principal component analysis (PCA). The flow-cell electronic tongue coupled with PCA is used to discriminate potable water samples from non-potable water contaminated with metals or traces of pesticides.

Nonwoven mats of poly(lactic acid) (PLA), poly(ethylene oxide) (PEO), and poly(ε-caprolactone) (PCL) were prepared at a nano- and submicron scale by solution blow spinning (SBS) and electrospinning in order to compare crystalline structure and morphology developed by both processes during fiber formation. Polymer solutions were characterized by rheometry and tensiometry. Spun fibers were characterized by several analytical steps. SEM analyses showed that both solution blow spun and electrospun fibers had similar morphology. Absence of residual solvents and characteristic infrared bands in the solution blow spun fibers for PLA, PCL, and PEO was confirmed by FTIR studies. XRD diffraction patterns for solution blow spun and electrospun mats revealed some differences related to distinct mechanisms of fiber formation developed by each process. Significant differences in thermal behavior by DSC were observed between cast films of PLA, PCL, and PEO and their corresponding spun nanofibers. Furthermore, the average contact angles for spun PLA and PCL were higher than for electrospun mats, whereas it was slightly lower for PEO. When comparing electrospun and solution blow spun fibers, it was possible to verify that fiber morphology and physical properties depended both on the spinning technique and type of polymer.