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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.

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

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.

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

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.

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

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

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

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

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

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

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.

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

Mass testing for the diagnostics of COVID-19 has been hampered in many countries owing to the high cost of the methodologies to detect genetic material of SARS-CoV-2. In this paper, we report on a low-cost immunosensor capable of detecting the spike protein of SARS-CoV-2, including in samples of inactivated virus. Detection is performed with electrical impedance spectroscopy using an immunosensor that contains a monolayer film of carboxymethyl chitosan as matrix, coated with an active layer of antibodies specific to the spike protein. In addition to a low limit of detection of 0.179 fg/mL within an almost linear behavior from 10−20 g/mL to 10−14 g/mL, the immunosensor was highly selective. For the samples with the spike protein could be distinguished in multidimensional projection plots from samples with other biomarkers and analytes that could be interfering species for healthy and infected patients. The excellent analytical performance of the immunosensors was validated with the distinction between control samples and those containing inactivated SARS-CoV-2 at different concentrations. The mechanism behind the immunosensor performance is the specific antibody-protein interaction, as confirmed with the changes induced in C–H stretching and protein bands in polarization-modulated infrared reflection absorption spectra (PM-IRRAS). Because impedance spectroscopy measurements can be made with low-cost portable instruments, the immunosensor proposed here can be applied in point-of-care diagnostics for mass testing even in places with limited resources., This work was supported by National Council for scientific and Technological Development (CNPq) (Grant #103266/2020-8), São Paulo Research Foundation (FAPESP) (Grants # 2020/04579-7, 2020/08744-2, 2018/18953-8 and 2018/22214-6), SISNANO (MCTI) and Agronano Network. The authors also are grateful to CNPEM researchers Maria Helena Piazzetta and Angelo Gobbi for their assistance in electrode fabrication

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

Natural rubber (NR) is a raw material that presents unique properties and has many industrial applications. However, due to the global commercial demand for rubber, there is still need for research to increase its production and quality. In this work, the physicochemical, thermal, and structural properties of the latex and dry rubber of four rubber tree clones and the relation to NR final properties were assessed over two extraction periods. The intra- and inter-clone comparison results were evaluated using analysis of variance and the multiple comparison tests. The greatest variation among clones and between tapping periods was observed with regard to chemical composition. All clones showed uniformity in the thermal and structural evaluations. The results allowed comparison among the clones, the extraction periods and within the same clone, enabling analysis of performance and uniformity of the rubber produced, which are highly wanted characteristics in the NR and latex industry.

This study reports the generation of curaua-derived carbon dots (C-dots) and their suitability for Fe(III) detection, bioimaging and FACS analysis. C-dots were generated from curaua (Ananas erectifolius) fibers by a facile one-step hydrothermal approach. They exhibited graphite-like structure with a mean diameter of 2.4 nm, high water solubility, high levels of carboxyl and hydroxyl functional groups, excitation-dependent multicolor fluorescence emission (in the range 450 nm - 560 nm) and superior photostability. C-dots were highly selective and effective for the detection of ferric Fe(III) ion in an aqueous medium with a detection limit of 0.77 μM in the linear range of 0–30 μM, a value much lower than the guideline limits proposed by the World Health Organization (WHO). In biological cell systems, C-dots were very well tolerated by B16F1 mouse melanoma and J774.A1 mouse macrophages cell lines, both of which effectively internalized C-dots in their cytoplasmic compartment. Finally, C-dots were effective probes for long-term live cell imaging experiments and multi-channel flow cytometry analysis. Collectively, our findings demonstrate that curaua-derived C-dots serve as versatile and effective natural products for Fe(III) ion sensing, labeling and bioimaging of various cell types. This study adds novel C-dots to the library of carbon-based probes and paves the way towards a sustainable conversion of a most abundant biomass waste into value-added products.

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

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

Food packaging materials are traditionally expected to contain foodstuffs and protect them from deteriorating agents. Although petroleum-derived polymers have been widely used for this purpose, the rising concern with their nonrenewable and/or nonbiodegradable nature paves the route for the development of greener alternatives, including polysaccharides and polypeptides. The use of these food-grade biomacromolecules, in addition to fruits and vegetables, provides edible packaging with suitable physical-mechanical properties as well as unique sensory and nutritional characteristics. This text reviews the chronological development pathway of films based on fruit and vegetable purees, pomaces, and extracts. Recent advances are extensively reviewed with an emphasis on the role that each film component plays in the resulting materials, whose production methods are examined from a technical standpoint and essential properties are compiled and contrasted to their conventional, synthetic counterparts. Finally, this comprehensive review discusses advantages and limitations of edible films based on fruits and vegetables.

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.

Sensors and biosensors for monitoring food traceability, quality, safety, and nutritional value are of outmost importance nowadays. Electrospinning, a simple, straightforward and versatile technique to fabricate 1D micro- and nanomaterials, is among the most potential strategies to further advance the development of chemical (bio)sensors. Electrospun nanofibers are capable of improving several attributes of chemical (bio)sensors due to the high specific surface area, high porosity and 1-D confinement characteristics. Furthermore, the possibility to buildup multifunctional nanostructures by functionalizing the nanofiber surface with a wide range of distinct nanomaterials (such as carbon nanotubes, graphene, nanoparticles and conjugated polymers), enhances the (bio)sensing capabilities through additional properties and synergistic effects. In this review, we outline the representative progress in the last decade on the development of multifunctional hybrid electrospun nanofibers of varied morphology and composition, and their applications in chemical (bio)sensor platforms for analysis of food and agricultural products.

The development of novel graphene-based nanocomposites is a hotspot in materials science due to their unique optical, electronic, thermal, mechanical and catalytic properties for varied applications. The present work reports on the development of a graphene-based ternary nanocomposite of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate), reduced graphene oxide and gold nanoparticles (PEDOT:PSS-rGO-AuNPs) for the detection of hydrogen peroxide (H 2 O 2 ). The hybrid nanocomposite showed superior electrochemical properties and higher stability compared to each individual component as electrode materials, showing a synergistic effect between PEDOT, rGO and AuNPs. The nanocomposite was obtained via a facile one-step approach and was assembly with horseradish peroxidase (HRP). The PEDOT:PSS-rGO-AuNPs-HRP modified electrode has been used for the amperometric detection of H 2 O 2 and exhibited a high sensitivity of up to 677 μA mM −1 cm −2 , with a wide linear range from 5 to 400 μM and a low detection limit of 0.08 μM (S/N = 3). This developed enzymatic biosensor showed to be highly stable and unresponsive to potentially interfering substances, and it could be used for sensing H 2 O 2 in real samples, including tap water and bovine milk samples. These enhanced sensing performance could be ascribed to the intimate contact of AuNPs onto the rough surface of the PEDOT:PSS-rGO nanocomposite, which has a high electrical conductivity and large surface area, providing it as an excellent substrate for the growth and support of nanoparticles. The method developed in this work opens up a general route to prepare a wide range of graphene-based hybrid nanocomposite films with multiple functions including sensing and biosensing.

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

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

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

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

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

The tremendous risk of climate change and environmental problems has drastically endangered the survival and development of human society, which certainly demand modern technologies that require high-performance materials with superior properties. Photocatalysis is a promising, greener, and eco-friendly technology for pollution remediation, energy conversion, and chemical synthesis. Moreover, this technology has emerged as a powerful tool to design and in the development of engineered materials. In this association, functionalized polymers and their (nano) composites are not only used as fillers in polymer matrices but also play a significant role as hosts or supporting materials for inorganic metals and semiconductors (TiO2, ZnO, Fe2O3, and so on). As efficient supporting materials in photocatalysis, functionalized polymeric composites derived either from natural or synthetic polymers are gaining much attention from governments, industries, and academia on the account of their low cost, environmental compatibility, and replacement capability for petroleum-derived products. This chapter provides a comprehensive understanding for obtaining photocatalytic organic/inorganic hybrid (nano) composites from natural and synthetic functionalized polymers and their wastewater treatment applications. Two different categories of functionalized polymers, namely, (i) natural polymers and (ii) synthetic polymers, and their composite materials along with their recent advancement in wastewater treatment by light-responsive photocatalysis are figured out.