Search

Alzheimer's disease (AD) is the most common form of dementia and affect more than 50 million people worldwide. Thus, there is a high demand by non-invasive methods for an early diagnosis. This work explores the AD diagnostic using the amyloid beta 1-40 (Aβ40) peptide encapsulated into dipalmitoyl phosphatidyl glycerol (DPPG) liposomes and immobilized on polyethylene imine previously deposited on screen-printed carbon electrodes to detect autoantibodies against Aβ40, a potential biomarker found in plasma samples.The immunosensor assembly was accompanied by atomic force microscopy (AFM) images that showed globular aggregates from 20 to 200 nm corresponding liposomes and by cyclic voltammetry (CV) through increase of the voltammogram area each material deposited. After building the immunosensor, when it was exposed to antibody anti-Aβ40, there was an increase in film roughness of approximately 9 nm, indicating the formation of the immunocomplex.In the detection by CV, the presence of specific antibody, in the range of 0.1 to 10 μg/ml, resulted in an increase in the voltammograms area and current in 0.45 V reaching 3.2 µA.V and 5.7 μA, respectively, in comparison with the control system, which remained almost unchanged from 0.1 μg/ml. In patient samples, both cerebrospinal fluid (CSF) and plasma, was possible separated among positive and negative samples for AD using CV profile and area, with a difference of 0.1 μA.V from the upper error bar of healthy samples for CSF sample and 0.6 μA.V for plasma sample.These results showed the feasibility of the method employed for the non-invasive diagnostic of Alzheimer's disease detecting natural autoantibodies that circulate in plasma through a simple and easy-to-interpret method.

Made available in DSpace on 2021-06-25T11:14:00Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-03-21 Photocatalyst-coated self-cleaning ceramic tiles are in high demand for indoor and outdoor applications aimed at keeping a clean environment. Their industrial processing, however, often requires firing at temperature (1000-1200 °C) much higher than the thermal stability limits of common photocatalysts (

Made available in DSpace on 2020-12-12T01:15:00Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-06-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) The challenge to obtain stable glasses containing monodisperse magnetic nanoparticles with controlled size and shape is an exciting and almost unexplored field of research. Such new materials can be used in magneto-photonics or ultra-sensitive magnetic sensors. In this work, for the first time, colorless and transparent bulk glasses containing monodisperse 20 nm Fe3−δO4 nanoparticles were prepared by a melt-quenching route. Magnetic nanoparticles were synthesized by thermal decomposition and covered with a stellate mesoporous silica shell in order to protect them against dissolution during the glass melting process. The incorporation of nanoparticles into glasses and the ideal parameters obtained for this system are discussed. The new nanocomposite materials were characterized in order to investigate the structure, thermal, and magnetic properties. Such an original approach is a very promising way to incorporate a wide panel of nanoparticles, including metallic, bimetallic and metal oxide nanoparticles, into a variety of glasses providing new properties to these materials. São Paulo State University - UNESP Institute of Chemistry, P. O. Box 355 Université de Strasbourg CNRS Institut de Physique et Chimie des Matériaux de Strasbourg UMR 7504 São Paulo State University - UNESP Institute of Chemistry, P. O. Box 355 CNPq: 153762/2018-7 FAPESP: 2013/07793-6 FAPESP: 2018/07727-7 FAPESP: 2019/19609-1 CAPES: 88881.134870/2016-01

The coacervation process of Graham’s Salt Na(PO3)n enabled the preparation of polyphosphate coacervates (CPPs) by adding different metallic ions (Mn+), and/or low-molecular-weight solvents at a specific solution, which resulted in a phase separation. The more viscous phase is termed as CPP and the less viscous one is the supernatant. CPPs have been extensively studied in recent years as a glass precursor at room temperature. Preparation at room temperature allows the preservation of the physicochemical properties of a wide range of active principles that may be used in controlled drug-delivery systems. Despite the present limitations of CPPs in terms of high hygroscopicity, this vulnerability to water is considered one of the great advantages of this material regarding applications in the controlled release of drugs and tissue engineering. Thus, in the presence of water, CPPs will dissolve in calcium and phosphate ions, which are the major inorganic constituents of bone and hydroxyapatite (HAP). It is believed that, in contact with body fluids, CPPs will degrade and, as this process occurs, they will be replaced by HAP. Therefore, CPPs configure a potential biomaterial that offers excellent properties with a wide range of biomedical applications that will be discussed and reviewed in this paper, including the structural properties and the recent improvements of materials based on CPPs and related devices.

Commodity counterfeiting can be resolved by attaching labels made from biopolymers and down- and up-converting particles. Measurements of luminescence spectrum and SEM were made, proving the formation of particles and luminescence.

In this work, UCNPs nanoparticles were modified with PAA on the surface to facilitate interaction with IgG antibodies from specific bacteria with potential for application in biosensors.

Laponite can improve mechanical strength and preserve the flexibility of sustainable polymers films desirable for application as a Flexible Organic Light-Emitting Diodes substrate. The nanocomposites were based on laponite and carboxymethyl cellulose/hyaluronic acid. The nanocomposites showed adequate flexibility, as well as the laponite showed good dispersion in the polymeric matrix, making them a good candidate for final application as a substrate for FOLED devices.

Bismuth vanadate (BiVO4, BV) is a widely explored photocatalyst for photo(electro)chemical applications, but its full photocatalytic potential is hindered by the fast recombination and low mobility of photogenerated charge carriers. Herein, we propose the photodeposition of different amounts of Prussian blue (PB) cocatalysts on the surface of monoclinic BV to obtain BV-PB composite photocatalysts with increased photoactivity. The as-prepared BV and BV-PB composites were characterized by an array of analytic techniques such scanning eletron microscopy (SEM), transmission eletron microscopy (TEM), X-day diffraction (XRD), and spectroscopic techniques including Fourier-transform infrared spectroscopy (FTIR), diffuse reflectance spectroscopy (DRS), electrochemical impedance spectroscopy (EIS), photoluminescence (PL), and Raman spectroscopy. The addition of PB not only increases the absorption of visible light, as indicated by DRS, but also improves the charge carriers’ transfer across the photocatalysts/solution interface and hence reduces electron-hole (e−-h+) recombination, as confirmed by EIS and PL measurements. Resultantly, the BV-PB composite photocatalysts with optimum PB loading exhibited enhanced Cr(VI) photoreduction efficiency as compared to pristine BV under visible light illumination from low-power blue light-emitting diodes (LEDs), thanks to the cocatalyst role of PB which mediates the transfer of photoexcited conduction band (CB) electrons from BV to Cr(VI) species in solution. Moreover, as compared to pristine BV and BV + H2O2, a drastic increase in the methylene blue (MB) photo-oxidation efficiency was observed for BV-PB in the presence of a minute quantity of H2O2 due to a synergic effect between the photocatalytic and Fenton-like processes. While pure BV photodegraded around 70% of MB dye within 120 min, the BV-PB/H2O2 and BV/H2O2 system could degrade almost 100% of the dye within 20 min (kobs. = 0.375 min−1) and 40 min (kobs. = 0.055 min−1), respectively. The practical approach employed in this work may pioneer new prospects for synthesizing new BV-based photocatalytic systems with low production costs and high photoredox efficiencies.

Hybrid organic-inorganic polyurethane films based on Castor Oil (CO) was made and characterized by FTIR-ATR, UV-Vis, and fluorescence spectroscopy, showing blue luminescence. The present work is an initial investigation of the application of the films in the photonics field.

The luminescence quenching by aggregation of carbon dots (CD) could be solved by functionalizing the surface with an alkoxysilane, bounding the nanoparticle directly in the polymer network.The reaction was monitored with ATR-FTIR and bacterial cellulose (BC) was coated with the precursor using sol-gel route, showing blue luminescence of CD.

As the development of nanotechnology progresses, organic electronics have gained momentum in recent years, and the production and rapid development of electronic devices based on organic semiconductors, such as organic light-emitting diodes (OLEDs), organic photovoltaic cells (OPVs), and organic field effect transistors (OFETs), among others, have excelled. Their uses extend to the fabrication of intelligent screens for televisions and portable devices, due to their flexibility and versatility. Lately, great efforts have been reported in the literature to use them in the biomedical field, such as in photodynamic therapy. In tandem, there has been considerable interest in the design of advanced materials originating from natural sources. Bacterial nanocellulose (BNC) is a natural polymer synthesized by many microorganisms, notably by non-pathogenic strains of Komagataeibacter (K. xylinus, K. hansenii, and K. rhaeticus). BNC shows distinct physical and mechanical properties, including its insolubility, rapid biodegradability, tensile strength, elasticity, durability, and nontoxic and nonallergenic features, which make BNC ideal for many areas, including active and intelligent food packaging, sensors, water remediation, drug delivery, wound healing, and as conformable/flexible substrates for application in organic electronics. Here, we review BNC production methods, properties, and applications, focusing on electronic devices, especially OLEDs and flexible OLEDs (FOLEDs). Furthermore, we discuss the future progress of BNC-based flexible substrate nanocomposites.

Luminescence thermometry has substantially progressed in the last decade, rapidly approaching the performance of concurrent technologies. Performance is usually assessed through the relative thermal sensitivity, Sr, and temperature uncertainty, ����T. Until now, the state-of-the-art values at ambient conditions do not exceed maximum Sr of 12.5% K���1 and minimum ����T of 0.1 K. Although these numbers are satisfactory for most applications, they are insufficient for fields that require lower thermal uncertainties, such as biomedicine. This has motivated the development of materials with an improved thermal response, many of them responding to the temperature through distinct photophysical properties. This paper demonstrates how the performance of multiparametric luminescent thermometers can be further improved by simply applying new analysis routes. The synergy between multiparametric readouts and multiple linear regression makes possible a tenfold improvement in Sr and ����T, reaching a world record of 50% K���1 and 0.05 K, respectively. This is achieved without requiring the development of new materials or upgrading the detection system as illustrated by using the green fluorescent protein and Ag2S nanoparticles. These results open a new era in biomedicine thanks to the development of new diagnosis tools based on the detection of super-small temperature fluctuations in living specimens., This project has received funding from the European Union's Horizon 2020 FET Open programme under grant agreement No 801305 (NanoTBTech). This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie Grant Agreement No. 823941.

Made available in DSpace on 2020-12-11T04:37:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-01-01. Added 1 bitstream(s) on 2021-07-15T14:37:29Z : No. of bitstreams: 1 S0100-40422019004901038.pdf: 3214993 bytes, checksum: a54c5bfbdc1b315619f32b8367a896e0 (MD5) NSERC (Canada) CFI BCKDF University of Victoria Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) A bioanalytical method for HIV detection based on surface-enhanced Raman scattering (SERS) is described. The assay targeted the peptide p17-1. This peptide sequence is present in the protein p17, a structural protein essential in the life cycle of the human immunodeficiency retrovirus (HIV). The antibody anti-p17 was immobilized in a planar gold surface using self-assembled techniques. This planar platform was used to capture the target analyte (p17-1 peptide). The peptide detection was carried out using specially designed SERS probes, consisting of gold nanoparticles coated with a Raman reporter molecule (Nile Blue A) and functionalized with anti-p17. This sandwich assay led to the successful detection of the peptide p17-1 at 40.8 ng/mL levels. The sandwich assay described here demonstrated that the SERS technique can rival more common fluorescence methods, such as ELISA, in the detection HIV-type virus. Univ Estadual Paulista, Inst Quim, BR-14800900 Araraquara, SP, Brazil Univ Victoria, Dept Chem, Victoria, BC, Canada Univ Fed Sao Paulo, Inst Ciencia & Tecnol, BR-12247014 Sao Jose Dos Campos, SP, Brazil Univ Victoria, Ctr Adv Mat & Related Technol, Victoria, BC, Canada Univ Estadual Paulista, Inst Quim, BR-14800900 Araraquara, SP, Brazil

The diagnostics of the autoimmune hemolytic anemia (AIHA), a rare disease caused by autoantibody-induced hemolysis, is still prone to false positives for it is based on visual observation in the so-called Direct Coombs test. In this study, we developed a specific IgG hemolysis immunosensor produced with layer-by-layer (LbL) films containing a monoclonal antibody against human immunoglobulin (mAbIMUG) deposited along with a layer of silk fibroin (SF) derived from Bombyx mori cocoons. Adsorption of mAbIMUG on a SF layer was confirmed by the fluorescence emission band at 326 nm. Immunosensors were prepared with LbL films deposited on interdigitated gold electrodes for impedance spectroscopy and on screen printed carbon electrodes for electrochemical measurements. When the SF/mAbIMUGLbL film was exposed to healthy red blood cells (RBCs), no cell binding was observed by the optical microscopy images. In addition, no major changes were observed in the signals of the square wave voltammogram and in the impedance spectra. In contrast, the electrochemical signal was significantly increased and the dielectric loss curve shifted for the sensing units containing RBCs with the antibody attached on the surface ("sick cells"). Furthermore, cell attachment was so strong that optical images still showed covered electrodes even after washing in PBS buffer. The detection with two distinct methods seems promising for an effective diagnosis of AIHA.

Made available in DSpace on 2019-10-06T17:10:07Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-01-01 New Sb 2 O 3 -based heavy metal oxide glasses in the Sb 2 O 3 –WO 3 –ZnO ternary system were prepared using a conventional melt-quenching method. The glass-forming domain and physical properties like density, thermal, structural and linear optical properties of the glasses have been investigated. The physical properties of glasses have been studied extensively as a function of WO 3 and ZnO concentration (mol%) in the Sb 2 O 3 –WO 3 –ZnO ternary glassy system. It was found that the glass transition temperature increases linearly with WO 3 concentration, but thermal stability decreases, while both the glass transition temperature and thermal stability almost linearly increases with ZnO concentration. The glasses within 60Sb 2 O 3 –xWO 3 –(40 − x)ZnO ternary system with x = 10, 15 and 20 were found as most thermally stable glasses. The density and refractive index of these glasses increases as the content of WO 3 increases. The available free space in the glass i.e. free volume and optical band gap of the glass decreases with higher concentration of WO 3 . This work demonstrates that proper composition can lead to effective and beneficial change in physical properties of the Sb 2 O 3 -based glasses. Institute of Chemistry São Paulo State University (UNESP) Center for Optics Photonics and Lasers (COPL) Université Laval Institute of Chemistry São Paulo State University (UNESP)

Made available in DSpace on 2019-10-06T16:59:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-03-01 The search for more efficient catalysts and less polluting and less costly reagents has made heterogeneous catalysis one of the most advantageous processes in this scenario. In this work, recoverable heterogeneous catalysts were prepared by incorporating maghemite nanoparticles (M-NP) into mesoporous silica matrix and further coated with dense or mesoporous layers by the sol-gel process. The catalytic activity of the nanocomposites was evaluated in hydrocarbon oxidation accomplished by the epoxidation of Z-cyclooctene. The materials were characterized by small-angle-x-ray scattering (SAXS), transmission electron microscopy (TEM), nitrogen adsorption-desorption analysis that confirms the coating over the nanocomposites and also the dependence of the reagent amount on the thickness of coating. SAXS curves and nitrogen adsorption-desorption analysis are in agreement with typical profiles of well-ordered hexagonal lattice with the surface area obtained from BET analysis of 454 m 2 /g and the pore volume of 0.917 cm 3 /g for the non-coated mesoporous silica. TEM and XRD results show the formation of maghemite phase with nanoparticle diameters between 3.5 and 20 nm. In addition, the catalytic results show that the nanocomposites coated with a mesoporous silica coating displayed higher substrate conversion than those coated with dense silica coating. Universidade de Franca UNIFRAN, CP 82 São Carlos Physics Institute University of São Paulo, CP 369 Institute of Chemistry UNESP São Paulo State University, CP 355 Institute of Chemistry UNESP São Paulo State University, CP 355

Made available in DSpace on 2019-10-06T16:58:01Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-02-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Nowadays there is a demand for ecologically efficient sustainable materials. The combination of cellulose and clay can provide materials with improved mechanical, thermal, and optical properties, besides better water and gas barrier, and flame resistance than pristine polymers. In the present work, composites were produced using cellulose nanofibers (CNF) and Laponite. The presence of clay modified the properties of the composite films compared to the pristine cellulose nanofibers film, such as lower CNF aggregation, better thermal stability (45 °C for CNF/Lap 3.5:1 by mass) and higher water vapor permeability (157% for CNF/Lap 1:1). In addition, XRD data suggested isolation of different types of CNF/Laponite composites when the mass ratio is modified, pointing out applications for these materials as for instance scaffold in tissue engineering, in regenerative medicine or as drug delivery systems. Institute of Chemistry São Paulo State University-UNESP, CP 355 Research Center on Biotechnology – Uniara, Street: Carlos Gomes, 1338, Centro Department of Fundamental Chemistry Institute of Chemistry University of São Paulo (USP), Av. Prof. Lineu Prestes 748 Institute of Chemistry São Paulo State University-UNESP, CP 355

Phosphotellurite based glasses have interesting features such as low characteristic temperatures, high glass forming ability, high thermal stability against crystallization and a broad transparency window from ultraviolet (UV) to near-infrared (NIR), which makes them promising materials for photonic applications. In this work, phosphotellurite binary glasses, having a composition (100 − x)TeO2 − xBa(PO3)2 with x varying from 1 to 20 mol%, were synthesized by the conventional melt-quenching method in covered gold crucibles under air. Optical, physical and structural properties of the new glass samples were investigated by differential scanning calorimetry, X-ray diffraction, Raman spectroscopy, transmission electron microscopy, linear optical absorption from UV to NIR, IR transmittance, and optical limiting experiments. Transparent glass-ceramics in the visible range were obtained for phosphotellurite samples containing 2, 4 and 6 mol% of Ba(PO3)2 and the phase crystallization was investigated through Rietveld analysis and transmission electron microscopy. The incorporation of Ba(PO3)2 into the TeO2 network drastically increases the thermal stability against devitrification and helps to shift the infrared multiphonon absorption edge to longer wavelengths. Nonlinear measurements performed with a picosecond laser at 532 nm indicate large effective nonlinear absorption coefficients for all samples. In summary, the dependence of the spectroscopic properties on the compositions of the samples revealed promising transparent glass and glass-ceramics for photonic applications.

Lanthanide (Ln3+)-doped upconversion nanoparticles (UCNPs) have been paid great attention as multiplexing agents due to their numerous uses in biological and clinical applications such as bioimaging and magnetic resonance imaging (MRI), to name a few. To achieve efficient multicolor emission from UCNPs under single 808 nm excitation and avoid detrimental cross-relaxations between the Ln3+ activator ions (positioned in either the core and/or shell in the core/shell), it is essential to design an adequate nanoparticle architecture. Herein, we demonstrate the tailoring of multicolor upconversion luminescence (UCL) from Nd3+-sensitized Gd3+-based core/shell/shell UCNPs with an architecture represented as NaGdF4:Tm3+(0.75)/Yb3+(40)/Ca2+(7)/Nd3+(1)@NaGdF4:Ca2+(7)/Nd3+(30)@NaGdF4:Yb3+(40)/Ca2+(7)/Nd3+(1)/Er3+(X = 1, 2, 3, 5, 7) [hereafter named CSS (Er3+ = 1, 2, 3, 5 and 7 mol%)]. Such UCNPs can be excited at a single wavelength (∼808 nm) without generation of any local heat. Incorporation of substantial Nd3+-sensitizers with an appropriate concentration in the middle layer allows efficient harvesting of excitation light which migrates bi-directionally across the core/shell interfaces in sync to produce blue emission from Tm3+ (activator) ions in the core as well as green and red emission from Er3+ (activator) ions in the outermost shell. Introduction of Ca2+ lowers the local crystal field symmetry around Ln3+ ions and subsequently affects their intra 4f–4f transition probability, thus enhancing the upconversion efficiency of the UCNPs. By simple and precise control of the shell thickness along with tuning the content of Ln3+ ions in each domain, multicolor UCL can be produced, ranging from blue to white. We envision that our sub-20 nm sized Nd3+-sensitized Gd3+-based UCNPs are not only potential candidates for a variety of multiplexed biological applications (without impediment of any heating effect), but also can act as MRI contrast agents in clinical diagnosis.

Fertilization is essential to provide suitable conditions for plant development and crop productivity, but the environmental cost of fertilizer production is a drawback for achieving a sustainable agriculture. Using unprocessed (raw) nutrient sources such as elemental sulfur (S0) and mineral oxides (ZnO, MnO, CuO) as fertilizers reduces the environmental impact, although they are not readily available to plants. Thus, we developed a polymeric coating material based on gelatinized starch loaded with S0 and oxides, and selected microorganisms – Aspergillus niger and Aciditiobacillus thiooxidans – aiming at a multi-nutrient fertilizer in which the biological components improve the solubility of the low reactive nutrient sources. The acidifying capacity of both microorganisms led to a synergic release and increased the availability of micronutrients and the elemental sulfur oxidation rate. For instance, the polymeric coating composition enabled a sulfate release of up to 76.4 and 71.3% for A. niger and A. thiooxidans, respectively. This innovative system can effectively supply nutrients to plants through the use of cheap and low reactivity nutrient sources with the advantage that it can be applied on currently used fertilizer granules, making easier the adoption by producers.

Made available in DSpace on 2021-06-25T11:03:16Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-05-14 In this work, we synthesized colloidal silica nanospheres with an average size of 400 nm through the modified Stöber method and successfully fabricated an ordered close-packed silica nanosphere monolayer onto ITO-coated glass substrates using a three-step spin-coating method. ITO films showed resistivity comparable to that of commercial ITO and the silica nanosphere monolayer-coated ITO/glass substrate exhibited good optical transmittance in the visible (550 nm) and near-infrared (900 nm) regions of 62% and 82%, respectively. The results suggest that this monolayer can be used in optoelectronic devices to enhance efficiency in photovoltaic cells. Grupo de Nanociência e Nanotecnologia (NANO) Departamento de Física Universidade Federal de Juiz de Fora (UFJF) Laboratório de Biopolímeros e Biomateriais (BIOPOLMAT) Departamento de Biotecnologia Universidade de Araraquara (UNIARA) Departamento de Física Universidade Federal de Juiz de Fora (UFJF) Institudo de Química Universidade Estatual Paulista Julio de Mesquita Filho (UNESP) Laboratório de Optoeletrônica Molecular (LOEM) Departamento de Física Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio) Faculdade de Ciências Farmacêuticas Universidade Estatual Paulista Julio de Mesquita Filho (UNESP) Institudo de Química Universidade Estatual Paulista Julio de Mesquita Filho (UNESP) Faculdade de Ciências Farmacêuticas Universidade Estatual Paulista Julio de Mesquita Filho (UNESP)

Made available in DSpace on 2021-06-25T11:03:47Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-05-13 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Instituto Nacional de Fotônica Bacterial nanocellulose (BNC) is a natural biopolymer obtained by gram-negative bacteria by means of a green and inexhaustible biotechnological process using glucose as producing source. BCN hydrogels is formed by cellulose nanofibrils that maintain an open network structure, an ideal matrix to produce new class of organic-inorganic nanocomposites (OIN) for multifunctional applications. The polyoxometalates (POMs) are complex molecules with several metallic ions sharing oxide ions, forming a highly symmetrical metal oxide cluster. Phosphotungstic acid (PWA), H3PW12O40 photoreduction process activated under ultraviolet irradiation, promoting color change. In this work, photochromic organic-inorganic nanocomposites were prepared by soaking phosphotungstic acid (H3PW12O40) in wet BNC membranes mats at room temperature. Semi-transparent and free-standing BNC/PWA nanocomposite with paper-like aspect were obtained. BNC network was able to control, stabilize and disperse PWA particles in a narrow nanometric distribution, and FTIR spectra indicated that the primary Keggin structure was also preserved in the nanocomposites, independently on the PWA content. The nanoparticles present a narrow distribution of around 16 nm, independently on the PWA concentration. BNC/PWA nanocomposites showed reversible photochromic behavior characteristic of the equilibrium between different tungsten oxidation states. PWA reduction (W6+→ W5+) and organic matrix oxidation is proposed to occur through a radical process involving the interaction of one electron from the oxygen atom of the PWA and one hydrogen from BNC matrix. The photochromic effect vanishes almost completely after 5 h. This mechanism is real in the presence of oxygen, however, if the membranes are left in nitrogen or under vacuum the blue color remains longer than 45 days. Photo-electrochemical behavior was studied by spectroelectrochemistry measurements. It is worth noting that all processes were still reversible in the timescale of the experiment and color changes were observed in several cycles. Institute of Chemistry São Paulo State University (UNESP) Laboratório de Biopolímeros e Biomateriais (BioPolMat) Universidade de Araraquara Instituto de Química – Universidade de São Paulo USP Departamento de Física Instituto de Ciências Exatas Universidade Federal de Juiz de Fora (UFJF) Deparment of Chemistry Federal University of São Departamento de Física Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio) Institute of Chemistry São Paulo State University (UNESP) FAPESP: 2013/07793-6 FAPESP: 2013/24725-4 FAPESP: 2014/12424-2 FAPESP: 2016/11591-8 FAPESP: 2018/25512-8 FAPESP: 2020/04509-9 Instituto Nacional de Fotônica: 407822/2018-6

Made available in DSpace on 2021-06-25T11:14:30Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-03-30 Photonic materials featuring simultaneous iridescence and light emission are an attractive alternative for designing novel optical devices. The luminescence study of a new optical material that integrates light emission and iridescence through liquid crystal self-assembly of cellulose nanocrystal-template silica approach is herein presented. These materials containing Rhodamine 6G were obtained as freestanding composite films with a chiral nematic organization. The scanning electron microscopy confirms that the cellulose nanocrystal film structure comprises multi-domain Bragg reflectors and the optical properties of these films can be tuned through changes in the relative content of silica/cellulose nanocrystals. Moreover, the incorporation of the light-emitting compound allows a complementary control of the optical properties. Overall, such findings demonstrated that the photonic structure plays the role of direction-dependent inner-filter, causing selective suppression of the light emitted with angle-dependent detection. Institute of Chemistry São Paulo State University (UNESP) Department of Physics University of Aveiro Biopolymers and Biomaterials Laboratory University of Araraquara Institute of Chemistry São Paulo State University (UNESP)

Made available in DSpace on 2021-06-25T11:12:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-03-04 Bacterial cellulose (BC) combined with organo-bridged porous silica nanoparticles offers potential opportunities to develop smart hybrid materials such as advanced drug delivery nanosystems. This work reports the preparation of bacterial cellulose membrane (BCM) and their modification by in situ methodology with the organo-bridged precursor 1,4-bis(triethoxysilyl)benzene (BTEB). BTEB was successfully incorporated into the BCM, and spherical hybrid silica nanoparticles with heterogeneous particle size (30-100 nm) and probably porous structure were formed and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared-attenuated total reflectance (FTIR-ATR), thermogravimetric analysis (TGA), and solid state nuclear magnetic resonance (NMR). We further combined solid-state NMR with dynamic nuclear polarization (DNP) to achieve sensitivity enhancement and to selectively enhance the NMR signal of the hydrophobic BTEB moieties on the BCM surface. This allowed us to get more detailed structural information about the BTEB-BCM multicomponent material. Institute of Chemistry São Paulo State University (UNESP) São Carlos Institute of Physics University of São Paulo, PO Box 369 ICGM Univ. Montpellier CNRS ENSCM Institut für Physikalische Chemie Technische Universität Darmstadt University of Araraquara (UNIARA) Institute of Chemistry São Paulo State University (UNESP)

Made available in DSpace on 2021-06-25T10:17:58Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-03-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Ciência e Tecnologia do Estado de Pernambuco Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Owing to the tremendous possibility of contactless temperature probing with micro- and nanometric spatial resolution, photoluminescent single-particle thermometry at the micro or nanoscale is rapidly advancing towards its successful applications in electronics, biological thermal imaging, or investigating thermodynamics around microsystems, for instance. The first step is the characterization of a suitable sized particle which will play the role of a thermometer in the desired/needed size scale. To that end, possibilities of using Er3+/Yb3+ doped β-NaYF4 rare-earth single microcrystals are explored particularly in this work due to its luminescence efficiency in the visible band and morphological stability in a temperature range compatible with biological systems. Under CW excitation at 977 nm, the Er3+ ions in β-NaYF4 host allow observing photoluminescence around 525 nm and 547 nm, corresponding to the 2H11/2 → 4I15/2 and 4S3/2 → 4I15/2 transitions, respectively. As these 2H11/2 and 4S3/2 states are close enough in energy, it is expected the Luminescence Intensity Ratio (LIR) to follow a Maxwell-Boltzmann thermal distribution, but experiments performed in this work present a deviation from this prediction. This discrepancy is explained by an analytical and numerical solution of a system of rate equations, which shows that the nonradiative decay from 4S3/2 to 4F9/2 and the mechanism of excitation of the thermally coupled levels play an important role in the LIR analysis. Department of Physics Universidade Federal de Pernambuco (UFPE) Institute of Chemistry São Paulo State University (UNESP) Institute of Chemistry São Paulo State University (UNESP)

Made available in DSpace on 2021-06-25T11:08:37Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-02-01 This research study reports the formation of flexible and multifunctional organic-inorganic hybrid membranes (BC-SiO2-TiO2/Ag) based on bacterial cellulose (BC) that contain photoactive (TiO2) and antibacterial (Ag) components, rendering them photocatalytic, self-cleaning and UV-shielding properties (due to TiO2) as well as antibacterial activity. Coating of BC with sol-gel derived silica and titania particles was achieved through hydrolysis-polycondensation of tetraethyl orthosilicate and titanium (IV) isopropoxide, respectively, and a soft hydrothermal treatment (140 °C, 20 h) was used to obtain well-crystalline TiO2. The prepared BC-SiO2-TiO2/Ag photoactive membranes were characterized by an array of analytical techniques including XRD, XRF, SEM-EDS, electronic absorption spectroscopy and vibrational spectroscopy. The morphology of TiO2 coatings changes from a homogenous film-like smooth one to a rougher one consisting of randomly oriented titania particles (170 ± 35 nm) upon increasing the TiO2 loading of the membranes. These prepared photoactive BC-SiO2-TiO2 membranes exhibited excellent TiO2-loading dependent photocatalytic/self-cleaning activity towards crystal violet dye deposited as an over-layer on the surface of the membranes, degrading 97 % of the dye within 50 min of UV illumination. In addition to good photoactivity, the BC-SiO2-TiO2/Ag membranes demonstrated reasonable antibacterial activity against five different bacterial strains under dark conditions. These flexible BC-based hybrid membranes with photocatalytic, self-cleaning, antibacterial properties have the potential to be used in the design of self-cleaning and antibacterial surfaces, filters and facemasks that could be easily disinfected under UV irradiation from a lamp or natural sunlight and safely discarded and even recycled. Institute of Chemical Sciences University of Peshawar Institute of Chemistry São Paulo State University - UNESP, CP 355 Government Girls Degree College Institute of Research and Development Duy Tan University Institute of Physics Federal University of Mato Grosso do Sul Institute of Chemistry São Paulo State University - UNESP, CP 355

Made available in DSpace on 2021-06-25T11:12:58Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-04-01 Miniaturized environments have emerged as an excellent alternative to evaluate and understand biological mechanisms. These systems are able to simulate macroenvironments with high reproducibility, achieving many results in a short time of analysis. However, microenvironments require specific architectures that can be reached using laser micromachining techniques, such as two-photon polymerization (TPP). This technique has many advantages, allowing the production of environments without shape limitation and with special features. In this work, aided by the TPP technique, we produce different arrays of microstructures, fabricated using acrylate-based materials, in order to evaluate the growth and development of the Komagataeibacter xylinus bacteria, the micro-organism responsible for producing bacterial cellulose (BC), a natural polymer with several biological applications. BC grown in microenvironments presents similar features to those of biofilm formed in macroenvironments, maintaining their attractive properties. In addition, due to the high optical quality and mechanical resistance of the BC matrices, we use these films as flexible substrates in TPP experiments, obtaining promising results for tissue engineering studies. São Carlos Institute of Physics University of São Paulo Institute of Chemistry São Paulo State University (UNESP) Institute of Chemistry São Paulo State University (UNESP)