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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.

We have developed carbon quantum dots (CQDs) with excellent photoluminescence (PL) properties from macaúba (Acrocomia aculeate) fibers; a widely available cellulosic biomass species of palm trees in South America. As-prepared CQDs showed quasi-spherical morphology with high aqueous solubility, strong photostability and excitation dependent multicolor fluorescence behaviour. Interestingly, the CQDs display fluorescence 'turn-off' response with excellent sensitivity toward multi-metal ions including Fe3+, Cu2+ and Hg2+ with the very low detection limits of 0.69 µM, 0.99 µM, 0.25 µM, respectively. Notably, ascorbic acid (AA) induced a change in the (turn-off) fluorescence of Fe3+-CQDs, which caused an almost 70% revival of fluorescence (turn-on) by displacing Fe3+ ions. We have also harnessed CQDs as the visible-light-induced photocatalyst to reduce CO2 in water. Especially, the CQDs efficiently promote the photocatalytic reduction of CO2 into methane (CH4) with an evolution rate of 99.8 nmol/g at 436 nm in aqueous conditions. This indicates that the CQDs provide abundant active sites for CO2 adsorption and thus enhance the separation and migration of photo-induced charge carriers that efficiently reduce CO2 into CH4 without any co-catalyst in 100% water.

In this study we attempt to obtain ecological composites, produced from high density polyethylene (HDPE) and spent coffee grounds (SCG), 10–30% w/w, through extrusion and injection molding. The influence of the SCG concentration on the mechanical properties, microstructure, thermal and physical stability of the composites was determined. The incorporation of SCG fibers provided an increase of 49% (modulus of elasticity), and 108% (modulus of flexion) in the stiffness of composites. There was also an increase of approximately 13% in the elasticity of composites with 10% w/w SCG. In general, SCG particles up to 20% w/w were homogeneously dispersed in the HDPE matrix, showing good interaction and compatibility, without the need of a compatibilizer. Another important result was the maintenance of the thermal profile of the HDPE matrix with the incorporation of SCG, without causing processing modifications. Overall, the HDPE/SCG-based approach to obtaining natural fiber reinforced composite (NFRC) was promising, enabling the production of green composites using an underutilized resource, without negatively affecting its properties.

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.

Made available in DSpace on 2021-06-25T10:15:51Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-10-14 Nissan North America Food security is one of the biggest challenges for the next few decades, especially with the accelerated population growth rates. Therefore, achieving a better nutrient use efficiency is crucial to enhance crop yields and productivity, which depend directly on how macronutrients are supplied. It is notably complex because fertilizers are often applied as granules instead of more soluble powdered forms. Here, we propose a new model for an all-in-one NPK fertilizer production, which allows quickly adjustable compositions in multi-nutrient granules. Thus, thermoplastic starch has been used as a biodegradable matrix binder mixed with the fertilizers in a continuous process by extrusion. Urea and KCl were considered as N and K sources, respectively. P sources with different solubilities (triple superphosphate (TSP) and Bayovar and Patos phosphate rocks) have been tested and compared. The greenhouse experiment revealed that the TSP composite promoted superior biomass production than the standard application, in addition to an overall better nutrient uptake. While Bayovar did not benefit from the all-in-one granule, Patos results were improved in this system, revealing a boost in its solubilization. Embrapa Instrumentation Agricultural Research and Rural Extension Company of Santa Catarina Federal University of Saõ Carlos Department of Chemistry UNESP Botucatu Av. Universitaria Embrapa Pecuaria Sudeste UNESP Botucatu Av. Universitaria

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...

Detection of human papillomavirus 16 (HPV16) is essential for the diagnosis of cervix and head and neck cancer, which has prompted the development of biosensors to replace the sophisticated molecular techniques. In this paper, we employ a genosensor made with a HPV16 DNA probe (cpHPV16) immobilized on a layer-by-layer (LbL) film of chitosan and carbon nanotubes to detect a complementary sequence HPV16 oligo (ssHPV16). In addition to employing impedance spectroscopy, which has already been used in the literature, we detect ssHPV16 in buffer samples and in cancer cell line samples with UV-vis. spectroscopy. The limit of detection was 18.5 pmol L−1 in impedance spectroscopy measurements and 10.9 pmol L−1 in UV-vis measurements. Distinction of the various ssHPV16 concentrations and of the cancer cell line samples CasKi, SiHa, UMSCC-47, UM-SCC104 and 93-VU147T with both electrical and optical data could be made with the multidimensional projection technique referred to as interactive document mapping (IDMAP), with which we could confirm the absence of false positives by testing cell lines that did not contain ssHPV16 (JHU12, JHU13 and JHU28). The hybridization between cpHPV16 and ssHPV16 responsible for the biosensing was verified with polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS), while the concentration dependence could be modeled with a double Freundlich function. The use of optical absorbance measurements to detect ssHPV16 is promising toward a simple colorimetric detection.

Over the past few years, there has been a huge demand for developing sensors capable of monitoring and quantifying volatiles related to food quality analysis, medical diagnosis, and environmental m...

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.

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".

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.

PROCESSING AND APPLICATION OF POLYMERIC BIOMATERIALS: RECENT ADVANCES AND PERSPECTIVES. Biomaterials have been intensively investigated due to the increase in the elderly population and high prevalence of several disorders, such as cardiovascular and orthopedic diseases. Polymeric and composite polymeric materials in combination with different processing techniques, such as electrospinning, solution blow spinning, ultrathin film preparation, and 3D printing are promising for obtaining biomaterials with patient-specific applications. Here, we provide a review on recent advances and perspectives for synthetic and natural polymers as well as composites in the design of biomaterials. After introducing basic information about biomaterials, we describe the fundamentals of manufacturing techniques and highlight possible biomedical applications. Made available in DSpace on 2022-03-18T07:15:01Z (GMT). No. of bitstreams: 1 P-PROCESSAMENTO-E-APLICACAO-DE-BIOMATERIAIS-POLIMERICOS-AVANCOS-RECENTES-E.pdf: 1019144 bytes, checksum: b17958bcf825b201a38ed0548aa2d350 (MD5) Previous issue date: 2022

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.

In this paper, we report on machine learning to analyze the capacitance spectra obtained with an electronic tongue (e-tongue) and discriminate three endocrine-disrupting chemicals (EDC): bisphenol A, estrone, and 17-β-estradiol, and their mixtures. The e-tongue comprised seven sensing units made with interdigitated gold electrodes coated with layer-by-layer films of poly(o-methoxy aniline), poly(3-thiophene acetic acid), and molybdenum disulfide (MoS2). The Multilayer Perceptron (MLP), Random Forest, and Extreme Gradient Boosting (XGBoost) models were applied for multi-target regression to predict the concentration of individual contaminants and their mixtures. These machine learning models were evaluated according to the root mean square error (RMSE) values. The best performance was achieved with XGBoost for which RMSE ranged from 0.19 to 3.37 for individual contaminants, from 0.12 to 0.25 for the mixtures, and from 0.34 to 3.46 for the entire dataset. The high performance was only possible with a multi-target regression strategy, including a feature selection procedure. In the latter, the data were plotted with the parallel coordinate technique, and the silhouette coefficient was calculated, which is a quantitative measure of the ability to distinguish similar samples in a dataset. The usefulness of the machine learning methods is demonstrated by noting that the data from mixtures of EDCs could not be distinguished using multidimensional projections. Also significant is that this combination of machine learning and information visualization methodology is entirely generic; it may be applied to analyze data from e-tongues and other sensing and biosensing devices in prediction tasks as demanding as in the discrimination of mixtures of EDCs at concentrations below nmol L−1.

We report on genosensors to detect an ssDNA sequence from the SARS-CoV-2 genome, which mimics the GU280 gp10 gene (coding the viral nucleocapsid phosphoprotein), using four distinct principles of detection and treating the data with information visualization and machine learning techniques. Genosensors were fabricated on either gold (Au) interdigitated electrodes for electrical and electrochemical measurements or on Au nanoparticles on a glass slide for optical measurements. They contained a matrix of 11-mercaptoundecanoic acid (11-MUA) self-assembled monolayer (SAM) onto which a layer of capture probe (cpDNA) sequence was immobilized. Detection was performed using electrical and electrochemical impedance spectroscopies and localized surface plasmon resonance (LSPR). The highest sensitivity was reached with impedance spectroscopy, including using a low-cost (US$ 100) homemade impedance analyzer. Complementary ssDNA sequences were detected with a detection limit of 0.5 aM (0.3 copy per µL). This performance may be attributed to the high sensitivity of the electrical impedance technique combined with an appropriate arrangement of the sequences on the electrodes and hybridization between the complementary sequences, as inferred from polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS). The selectivity of the genosensor was confirmed by plotting the impedance spectroscopy data with a multidimensional projection technique (interactive document mapping, IDMAP), where a clear separation was observed among the samples of the complementary DNA sequence at various concentrations and from buffer samples containing a non-complementary sequence and other DNA biomarkers. The diagnosis of SARS-CoV-2 mimicking sequences was also achieved with machine learning techniques applied to scanning electron microscope images taken from genosensors exposed to distinct concentrations of the complementary ssDNA sequences. In summary, the genosensors proposed here are promising for detecting SARS-CoV-2 genetic material (RNA) in biological fluids in point-of-care settings., The authors are thankful to CAPES (88887.510657/2020-00 and 88887.364257/2019-00), São Paulo Research Foundation (FAPESP) (2013/14262, 2016/01919-6, 2018/18953-8, 2018/19750-3, 2018/22214-6, 2019/00101-8, 2019/13514-9, 2016/23763-8, 2019/07811-0, 2020/02938-0), INEO, INCTBio grants (FAPESP 2014/50867-3) and CNPq (423952/2018-8, 465389/2014-7, and 401256/2020-0) for the financial support. The authors are grateful to Angelo Luiz Gobbi and Maria Helena de Oliveira Piazzetta (LMF/LNNano/CNPEM) for producing the Au electrodes.

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.

Functional polymeric micro-/nanofibers have emerged as promising materials for the construction of structures potentially useful in biomedical fields. Among all kinds of technologies to produce polymer fibers, spinning methods have gained considerable attention. Herein, we provide a recent review on advances in the design of micro- and nanofibrous platforms via spinning techniques for biomedical applications. Specifically, we emphasize electrospinning, solution blow spinning, centrifugal spinning, and microfluidic spinning approaches. We first introduce the fundamentals of these spinning methods and then highlight the potential biomedical applications of such micro- and nanostructured fibers for drug delivery, tissue engineering, regenerative medicine, disease modeling, and sensing/biosensing. Finally, we outline the current challenges and future perspectives of spinning techniques for the practical applications of polymer fibers in the biomedical field.

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.

17α-ethinylestradiol (EE2) is a female synthetic hormone with a high estrogenic action that can potentially disrupt the organisms’ endocrine system, leading to severe health problems. Such fact increases the need for technologies capable of detecting this compound even at very low levels. In this context, here we report on the development of a highly sensitive electrochemical sensor for EE2 detection based on a novel nanoarchitecture composed of electrospun nanofibers of polyvinylpyrrolidone (PVP)/chitosan (Chi)/ reduced graphene oxide (rGO) functionalized with Laccase enzyme. The hybrid nanofibers deposited onto fluorine doped tin oxide (FTO) electrode showed good electrochemical properties with synergistic effect between PVP, Chi and rGO and suitability to assemble the enzyme Laccase. The PVP/Chi/rGO_Laccase modified electrode was used for EE2 amperometric detection showing a very low limit of detection of 0.15 pmol L−1 (3.3 σ/S), good reproducibility with relative standard deviation (RSD) equal to 4.29% and 8.44% to intra- and inter-electrode, respectively. In addition, the biosensor was shown to be selective for EE2 detection in the presence of several common interfering compounds. The developed platform was employed for real sample analysis, showing good accuracy towards EE2 determination in synthetic and human urine samples, suggesting the biosensor as a potential tool for the determination of EE2 in varied environments.

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.

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.

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.

Volatile organic compounds (VOCs) are associated to many problems regarding to health, such as cancer and asthma, and environmental issues, affecting ecosystem and plant growth development. Thus, reliable technologies capable to detect distinct VOCs in very low levels, both in indoor and outdoor environments, are highly desired. Although standard analytical techniques (such as chromatography and mass spectroscopy) can be used to detect varied VOCs, some of them do not combine sensitivity, precision and low cost. In this sense, the development of sensors employing hybrid nanomaterials designed for detecting VOCs appears as a suitable alternative due to remarkable features as superior sensitivity, limit of detection, possibility of miniaturization and versatility. The outstanding features of designed hybrid nanomaterials arise as consequence of the synergistic effects between the constituent materials, with direct consequence on the sensing mechanisms and performance. In this review article we present recent results on how the use of distinct nanomaterials, including conducting polymer, metals oxides, graphenes, etc., can be used to design nanoarchitectures to develop and improve the performance sensors for detecting VOCs aiming at varied applications. Keywords: Nanostructured material, Hybrid material, Sensor, Volatile organic compounds, Optical sensor, Electrochemical sensor

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.

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.