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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.

We report on layer-by-layer (LbL) films of chitosans (CHI) and hyaluronic acid (HA) whose properties could be controlled by employing chitosans with different degrees of deacetylation ( DD ¯ ≈ 85%; 65%; 40%) and high average molecular weight (ca. 106 g/mol). In spite of their high molecular weight, these chitosans are soluble within a wide pH range, including physiological pH. HA/CHI LbL films produced from polymer solutions at pH 4.5 were thinner, smoother, more hydrophilic than those prepared at pH 7.2. This is attributed to the more extended conformation adopted by chitosan due to its very high charge density at low pH, favoring a compact chain packing during the film formation and resulting in lower film thickness and roughness. The smoother HA/CHI LbL films obtained at pH 4.5 were effective against Escherichia coli, while the thicker, rougher LbL films fabricated at pH 7.2 could be used in the controlled released of Rose Bengal dye. In summary, the tuning of only two parameters, i.e. solution pH and DD ¯ of chitosans, provides access to a library of HA/CHI LbL films for tailored, diversified applications.

The design of optoelectronic devices made with ZnO superlattices requires the knowledge of the refractive index, which currently can be done only for films thicker than 30 nm. In this work, we present an effective medium approach to determine the refractive index of ZnO layers as thin as 2 nm. The approach was implemented by determining the refractive index of ZnO layers ranging from 2 nm to 20 nm using spectroscopic ellipsometry measurements in multilayers. For a precise control of morphology and thickness, the superlattices were fabricated with atomic layer deposition (ALD) with alternating layers of 2 nm thick Al

Made available in DSpace on 2020-12-12T02:06:11Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-10-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) The pursuit of biocompatible, breathable and skin-conformable wearable sensors has predominantly focused on synthetic stretchable hydrophobic polymers. Microbial nanocellulose (MNC) is an exceptional skin-substitute natural polymer routinely used for wound dressing and offers unprecedented potential as substrate for wearable sensors. A versatile strategy for engineering wearable sensing platforms is reported, with sensing units made of screen-printed carbon electrodes (SPCEs) on MNC. As-prepared SPCEs were used to detect the toxic metals cadmium (Cd2+) and lead (Pb2+) with limits of detection of 1.01 and 0.43 μM, respectively, which are sufficient to detect these metal ions in human sweat and urine. SPCEs functionalized through anodic pre-treatments were used for detecting uric acid and 17β-estradiol in artificial sweat, with detection limits of 1.8 μM and 0.58 μM, respectively. The electrochemical treatment created oxygen groups on the carbon surfaces, thus improving wettability and hydrophilicity. MNC was herein exploited as an adhesive-free, yet highly skin-adherent platform for wearable sensing devices that also benefit from the semi-permeable, non-allergenic, and renewable features that make MNC unique within the pool of materials that have been used for such a purpose. Our findings have clear implications for the developments on greener and more biocompatible but still efficient substrates and may pave the route for combining immunosensing devices with drug delivery therapies. São Carlos Institute of Physics University of São Paulo (USP) São Carlos Institute of Chemistry University of São Paulo (USP) Institute of Chemistry University of Campinas (UNICAMP), P.O. Box 6154 Biopolymers and Biomaterials Laboratory (BIOPOLMAT) University Center of Araraquara (UNIARA) Brazilian Nanotechnology National Laboratory (LNNano) Brazilian Center for Research in Energy and Materials (CNPEM) São Paulo State University (UNESP) Department of General and Inorganic Chemistry Rua Professor Francisco Degni, 55, Araraquara14800-060 São Paulo State University (UNESP) Department of General and Inorganic Chemistry Rua Professor Francisco Degni, 55, Araraquara14800-060 FAPESP: 2013/14262–7 FAPESP: 2015/01770–0 FAPESP: 2016/01919–6 FAPESP: 2016/06612–6 CNPq: 423952/2018-8

Submitted by Mirella Boaro Kobal (mirella.kobal@unesp.br) on 2021-02-24T03:02:20Z No. of bitstreams: 1 Sabrina_revised version_june_2020.docx: 1687573 bytes, checksum: 6cf2a10c103f27a85a34f8dcb1b03e57 (MD5) Rejected by Maria Luiza Carpi Semeghini (luiza@assis.unesp.br), reason: De acordo com a política desta revista, a versão do artigo a ser incluída no Repositório Institucional deve ser a versão aceita pela revista (postprint). Assim, o arquivo enviado em versão preprint deverá ser substituído pela versão postprint. Agradecemos a compreensão. Atenciosamente, Equipe do Repositório Unesp on 2021-02-25T18:40:58Z (GMT) Submitted by Mirella Boaro Kobal (mirella.kobal@unesp.br) on 2021-03-02T20:36:36Z No. of bitstreams: 1 Sabrina_revised version_june_2020.pdf: 1448731 bytes, checksum: a3d600b9a64085eae9442185c44611bb (MD5) Approved for entry into archive by Maria Luiza Carpi Semeghini (luiza@assis.unesp.br) on 2021-03-08T13:09:42Z (GMT) No. of bitstreams: 1 camacho_sa_postprint_assis_molecular.pdf: 1448731 bytes, checksum: a3d600b9a64085eae9442185c44611bb (MD5) Made available in DSpace on 2021-03-08T13:09:42Z (GMT). No. of bitstreams: 1 camacho_sa_postprint_assis_molecular.pdf: 1448731 bytes, checksum: a3d600b9a64085eae9442185c44611bb (MD5) Previous issue date: 2020-10 Outra Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Nanopartículas metálicas são agentes promissores para terapia fototérmica (TFT) em cânceres devido à sua fotoestabilidade e conversão eficiente de luz em calor, mas sua possível agregação continua sendo um problema. Neste artigo, relatamos o aquecimento fotoinduzido de nanopartículas de ouro recobertas com sílica (AuSHINs) em experimentos in vitro com células humanas de carcinoma de orofaringe (HEp-2) e de mama (BT-474 e MCF-7), com redução da viabilidade celular abaixo de 50% com 2,2 × 1012 AuSHINs / mL e 6 h de incubação. Esta toxicidade para as células cancerosas é significativamente maior do que em trabalhos anteriores com nanopartículas de ouro. Considerando as dimensões das AuSHINs, hipotetizamos que a absorção celular não é simples, e o mecanismo de ação envolve o acúmulo nas membranas fosfolipídicas, sendo o alvo da TFT para aquecimento fotoinduzido e geração subsequente de espécies reativas de oxigênio (ROS). Usando monocamadas de Langmuir como modelos de membrana simplificados, confirmamos que AuSHINs têm um efeito maior em 1,2-dioleoil-snglicero-3-fosfo-L-serina (DOPS), que se acredita representar as membranas de células cancerosas, do que em 1,2-dioleoil-sn -glicero-3-fosfocolina (DOPC) considerada como representante de células eucarióticas saudáveis. Em particular, dados de espectroscopia de absorção de reflexão de infravermelho modulada por polarização (PM-IRRAS) revelaram um aumento da ordem conformacional das caudas de DOPS devido à adsorção mais forte de AuSHINs. Além disso, a irradiação reduziu a estabilidade de AuSHINs contendo monocamadas de DOPC e DOPS devido às reações oxidativas desencadeadas por ROS mediante aquecimento fotoinduzido. Em comparação com o DOPC, o DOPS perdeu quase o dobro de material para a subfase, o que é consistente com uma taxa mais alta de formação de ROS na vizinhança da monocamada DOPS. Metallic nanoparticles are promising agents for photothermal cancer therapy (PTT) owing to their photostability and efficient light-to-heat conversion, but their possible aggregation remains an issue. In this paper, we report on the photoinduced heating of gold shell-isolated nanoparticles (AuSHINs) in in vitro experiments to kill human oropharyngeal (HEp-2) and breast (BT-474 and MCF-7) carcinoma cells, with cell viability reducing below 50 % with 2.2 × 1012 AuSHINs/mL and 6 h of incubation. This toxicity to cancer cells is significantly higher than in previous works with gold nanoparticles. Considering the AuSHINs dimensions we hypothesize that cell uptake is not straightforward, and the mechanism of action involves accumulation on phospholipid membranes as the PTT target for photoinduced heating and subsequent generation of reactive oxygen species (ROS). Using Langmuir monolayers as simplified membrane models, we confirmed that AuSHINs have a larger effect on 1,2-dioleoyl-sn-glycero-3-phospho-l-serine (DOPS), believed to represent cancer cell membranes, than on 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) taken as representative of healthy eukaryotic cells. In particular, data from polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS) revealed an increased conformational order of DOPS tails due to the stronger adsorption of AuSHINs. Furthermore, light irradiation reduced the stability of AuSHINs containing DOPC and DOPS monolayers owing to oxidative reactions triggered by ROS upon photoinduced heating. Compared to DOPC, DOPS lost nearly twice as much material to the subphase, which is consistent with a higher rate of ROS formation in the vicinity of the DOPS monolayer. Postprint Universidade Estadual Paulista (UNESP), Faculdade de Ciências e Letras, Assis Universidade de São Paulo (USP), Instituto de Física de São Carlos (IFSC) FAPESP: 2018/14692-5 FAPESP: 2018/16713-0 FAPESP: 2013/14262-7 FAPESP: 2018/22214- 6 CNPq: 403713/2016-1

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.

We report on the design of an all-dielectric quasiperiodic grating coupler with rectangular Si ribs on a SiO2 substrate. The structure consists of ten periods built by alternating Si ribs and air according to the S4 step of the Fibonacci series, i.e., the period was made as ABAAB, where A (B) can be used as Si (air) or air (Si). The thicknesses of air and Si ribs were taken as 315 nm, with a total length for the unit cell of 1575 nm. The finite- difference time-domain (FDTD) technique was used to obtain the numerical data within the commercial software Lumerical FDTD. Multiple coupling efficiency peaks were observed owing to self-similarity effects. Furthermore, we show numerically that optimum wavelengths and coupling efficiency amplitudes can be tailored by varying the ribs’ etch-depth and the angle of incidence from the optical fiber, which makes the proposal relevant for efficient, broadband optoelectronic circuits.

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.

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.

Made available in DSpace on 2020-12-12T02:41:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-08-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Instituto Nacional de Ciência e Tecnologia em Eletrônica Orgânica Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Risks to human health have been reported owing to prolonged exposure to hormones, whose action depends on their molecular-level interaction with cell membranes. In this study, we investigate the interaction of the synthetic hormone 17 α-ethynylestradiol (EE2) in two different membrane models, Langmuir monolayers and giant unilamellar vesicles (GUVs) made with a binary mixture of 1,2-dipalmitoyl-sn-glycerol-3-phosphocholine (DPPC) and cholesterol (Chol) in order to mimic the plasma membrane of mammalian cells. EE2 was found to expand the Langmuir monolayers, with shifts to larger areas per molecule in the surface pressure isotherm. In all of these observations, stronger effects were noted for the DPPC/Chol monolayers with XChol = 0.3, which mimics the proportion of phospholipid/sterol in the plasma membrane. At high surface pressures, EE2 is believed to weaken the attractive interactions between DPPC and Chol, in addition to affecting the ordering of the lipid chains as indicated in polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS) measurements. In GUVs obtained with XChol = 0.3 mixtures, EE2 induced a phase contrast loss as a result of increased permeability of the lipid bilayer. The results with Langmuir monolayers and GUV combined point to EE2 action on representative cell membranes, which can be correlated with physiological effects caused by indirect intake of EE2. Department of Physics School of Technology and Applied Sciences São Paulo State University (UNESP) Sao Carlos Institute of Physics University of Sao Paulo (USP) Department of Physics School of Technology and Applied Sciences São Paulo State University (UNESP) FAPESP: 2013/14262-7 FAPESP: 2016/09633-4 CAPES: 88882.330129/2018-01

Submitted by Lucas Gontijo Moreira (lucas.g.moreira@unesp.br) on 2021-03-10T12:02:08Z No. of bitstreams: 1 Pedro-Lucas-11Jul2020(no_marks)_tituloatt.pdf: 1177367 bytes, checksum: 25f0718fdfdb23798843c7f49b526e26 (MD5) Rejected by Maria Luiza Carpi Semeghini (luiza@assis.unesp.br), reason: Incluir o identificador ORCID de TODOS os autores UNESP on 2021-03-11T12:10:22Z (GMT) Submitted by Lucas Gontijo Moreira (lucas.g.moreira@unesp.br) on 2021-03-11T12:29:29Z No. of bitstreams: 1 Pedro-Lucas-11Jul2020(no_marks)_tituloatt.pdf: 1177367 bytes, checksum: 25f0718fdfdb23798843c7f49b526e26 (MD5) Approved for entry into archive by Maria Luiza Carpi Semeghini (luiza@assis.unesp.br) on 2021-03-12T22:35:17Z (GMT) No. of bitstreams: 1 moreira_lg_postprint_assis_chain.pdf: 1177367 bytes, checksum: 25f0718fdfdb23798843c7f49b526e26 (MD5) Made available in DSpace on 2021-03-12T22:35:17Z (GMT). No. of bitstreams: 1 moreira_lg_postprint_assis_chain.pdf: 1177367 bytes, checksum: 25f0718fdfdb23798843c7f49b526e26 (MD5) Previous issue date: 2020-07-16 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Photodynamic therapy (PDT) is promising for bacterial inactivation since cellular internalization of photosensitizers (PS) is not crucial for the treatment effectiveness. Photoinduced damage in the lipid envelope may already induce microbial inactivation, which requires PS capable of easily penetrating into the membrane. Herein, we report on the insertion of the PS eosin decyl ester (EosDec) into Langmuir films of 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE), 1,2-dioleoyl-sn-glycero-3-phospho-(1′-rac-glycerol) (DOPG), and cardiolipin (CLP) used as mimetic systems of bacterial membranes. Surface pressure isotherms and polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS) indicated that the hydrophobic nature of EosDec favored deeper penetration in all the phospholipid monolayers. The incorporation of EosDec led to monolayer expansion, especially in the anionic DOPG and CLP owing to repulsive electrostatic interactions, and induced disorder in the lipid chains. Light irradiation of DOPE, DOPG, and CLP monolayers containing EosDec increased the rate of material loss to the subphase, which is attributed to cleavage of lipid chains triggered by contact-dependent reactions between excited states of EosDec and lipid unsaturations. The latter is key for membrane permeabilization and efficiency in microbial inactivation. Postprint Faculdade de Ciências e Letras de Assis (UNESP) Instituto de Física de São Carlos (USP) Universidade Estadual de Maringá (UEM) FAPESP: 2013/14262-7 FAPESP: 2018/13021-0 FAPESP: 2018/16713-0 FAPESP: 2018/14692-5 FAPESP: 2018/22214-6 CNPq: 403713/2016-1

The increasing need for point-of-care diagnosis has sparked the development of label-free sensing platforms, some of which are based on impedance measurements with biological cells. Here, interdigitated electrodes were functionalized with layer-by-layer (LbL) films of hyaluronan (HA) and chitosan (CHI) to detect prostatic tumor cells (PC3 line). The deposition of LbL films was confirmed with atomic force microscopy and polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS), which featured the vibrational modes of the HA top layer capable of interacting specifically with glycoprotein CD44 receptors overexpressed in tumor cells. Though the CHI/HA LbL films cannot be considered as a traditional biosensor due to their limited selectivity, it was possible to distinguish prostate tumor cells in the range from 50 to 600 cells/&micro, L in in vitro experiments with impedance spectroscopy. This was achieved by treating the impedance data with information visualization methods, which confirmed the distinguishing ability of the films by observing the absence of false positives in a series of control experiments. The CD44&ndash, HA interactions may, therefore, be exploited in clinical analyses and point-of-care diagnostics for cancer, particularly if computational methods are used to process the data.

Electrochemical immunosensors have been developed to determine the carbohydrate antigen 19-9 (CA19-9). They are based on screen-printed carbon electrodes (SPCEs) coated with layer-by-layer (LbL) films of carbon black (CB) and polyelectrolytes. Owing to a suitable choice of LbL film architecture, the procedures for immobilization of anti-CA19-9 antibodies on the electrode surfaces were straightforward. Mechanically flexible immunosensors were capable of detecting CA19-9 within a dynamic range of 0.01 to 40 U mL−1 and a limit of detection of 0.07 U mL−1 using differential pulse voltammetry. In addition to detecting CA19-9 at clinically relevant concentrations for pancreatic cancer in standard solutions, the immunosensors provide the determination of CA19-9 on cell lysate and human serum samples. Using LbL films led to immunosensors with superior performance compared to similar systems obtained by drop casting. The fabrication of this relatively simple, inexpensive platform is a demonstration that SPCEs modified with cost-effective materials are able to detect cancer biomarkers and may be adapted to other disposable immunosensors.

The manufacture of sensors using large-scale production techniques, such as roll-to-roll (R2R) processing, may fulfill requirements of low-cost disposable devices. Herein, we report the fabrication of fully-printed electrochemical sensors using screen-printed carbon electrodes coated with carbon black inks through slot-die coating within an R2R process. As a proof of concept, sensors were produced to detect the neurotransmitter dopamine with high reproducibility and low limit of detection (0.09 μmol L−1). Furthermore, fully-printed biosensors made with a tyrosinase-containing ink were used to detect catechol in natural water samples. Since slot-die deposition enables printing enzymes without significant activity loss, the biosensors exhibited high stability over a period of several weeks. Even more important, R2R slot-die coating may be extended to any type of sensors and biosensors with the possibility of large-scale manufacturing.

In this paper we employ finite difference time-domain (FDTD) calculations to demonstrate the enhancement of chiroptical activity in high refractive index dielectric slotted nanodisks. The chiral enhancement mechanism consists of pairing the electric and magnetic modes of the slit cavity with the resonances of the rest of the disk, i.e., the weak chiroptical activity ($\ensuremath{\sim}{10}^{\ensuremath{-}1}$) inside the chiral gap region (which is chiral itself) is enhanced through the interaction with the electric and magnetic resonances in the nanodisk. These results are extended to a two-dimensional periodic arrangement of slotted nanosdisks forming a metasurface. The chiral electromagnetic near field at the slotted region can be harnessed for increasing the asymmetry in energy absorption of circularly polarized light (CPL). This chiral enhancement makes this novel metasurface useful for sensing or to control the optical forces that can be exerted on chiral molecules placed in those slotted regions. The latter can be relevant to the pharmaceutical industry since distinct enantiomers of racemic drugs frequently exhibit different biological activities.

A disposable electrochemical immunosensors is presented suitable to detect cancer biomarker p53 using screen-printed carbon electrodes modified with a layer-by-layer (LbL) matrix of carboxylated NiFe

Point-of-care (PoC) diagnostics is promising for early detection of a number of diseases, including cancer, diabetes, and cardiovascular diseases, in addition to serving for monitoring health conditions. To be efficient and cost-effective, portable PoC devices are made with microfluidic technologies, with which laboratory analysis can be made with small-volume samples. Recent years have witnessed considerable progress in this area with &ldquo, epidermal electronics&rdquo, including miniaturized wearable diagnosis devices. These wearable devices allow for continuous real-time transmission of biological data to the Internet for further processing and transformation into clinical knowledge. Other approaches include bluetooth and WiFi technology for data transmission from portable (non-wearable) diagnosis devices to cellphones or computers, and then to the Internet for communication with centralized healthcare structures. There are, however, considerable challenges to be faced before PoC devices become routine in the clinical practice. For instance, the implementation of this technology requires integration of detection components with other fluid regulatory elements at the microscale, where fluid-flow properties become increasingly controlled by viscous forces rather than inertial forces. Another challenge is to develop new materials for environmentally friendly, cheap, and portable microfluidic devices. In this review paper, we first revisit the progress made in the last few years and discuss trends and strategies for the fabrication of microfluidic devices. Then, we discuss the challenges in lab-on-a-chip biosensing devices, including colorimetric sensors coupled to smartphones, plasmonic sensors, and electronic tongues. The latter ones use statistical and big data analysis for proper classification. The increasing use of big data and artificial intelligence methods is then commented upon in the context of wearable and handled biosensing platforms for the Internet of things and futuristic healthcare systems.

International audience; The ability to disperse metallic nano-objects in a given matrix material is an important issue for the design and fabrication of functional materials. A means to monitor the spatial distribution of the nano-dopants is highly desirable but often possible only a posteriori and with destructive techniques. Here we present a spectroscopic characterization based on different plasmonic responses of silver nanoparticles, their agglomerates, and finally the percolated silver film. We demonstrate its usefulness for the specific case of their dispersion in layer-by-layer polymeric films but the method is extendable to any other host material transparent in the visible/near UV range. Individual silver nanoparticles display the well-known localized surface plasmon resonance around 400 nm, which is red-shifted upon inter-particle coupling. The transition regime between weakly coupled particles and fully percolated metal films is, however, much harder to evidence unambiguously. We show here how to monitor this transition using the so-called Ferrell plasmon, a plasmonic mode of the thin film in the mid-UV, and excitable only under oblique irradiation but without specific coupling precautions. We can thus follow the entire transition from isolated to coupled and finally to fully agglomerated nanoparticles by optical spectroscopy.

Hypothesis The interaction of chitosan, a natural biopolymer with various biomedical applications, with lipid Langmuir films has been widely investigated as a simple model for cell membranes. However, to ensure polymer solubility, up to now only acidic subphases with pH significantly below biological fluids have been used. To increase the biological significance of these investigations, here we evaluated the effects of two chitosan derivatives (low molecular weight − CH, and positively charged − CH-P40) on phospholipid films (either zwitterionic DPPC or anionic DPPG) using phosphate buffered saline solutions (PBS) as a subphase. Experiments Surface pressure − area (π−A) isotherms were used to evaluate the expansion and changes in film elasticity, while Sum-Frequency Generation (SFG) vibrational spectroscopy provided information about the chain conformation of lipids. Findings It was found that chitosans caused a small expansion of the DPPC film by its insertion within the monolayer. In contrast, they distinctly expanded DPPG monolayers by both chitosan insertion within the lipid monolayer and by interacting with the anionic head group. Therefore, PBS buffer can be used as a subphase for more biologically relevant studies of chitosan interactions with Langmuir films, shedding light on why chitosan is antibacterial but not toxic to mammals, as the interaction mechanism depends on lipid headgroup charge.

Langmuir monolayers have been used as cell membrane models, where lipid composition is normally varied to mimic distinct types of membranes. For eukaryotic membranes, for instance, rather than using only zwitterionic phospholipids there is now a trend to employ mixtures to simulate the lipid rafts known to be relevant for various cellular processes. In this study, we demonstrate that effects from chitosans on Langmuir monolayers are considerably higher if lipid raft compositions (ternary mixtures of dipalmitoyl phosphatidyl choline (DPPC), sphingomyelin (SM) and cholesterol) are used. Significantly, measurable effects on the surface pressure isotherms start at 10-6 mg mL-1 for chitosans in lipid rafts, to be compared with 10-2 mg mL-1 for neat dipalmitoyl phosphatidylcholine (DPPC). This applies to both a commercial chitosan and chitosans soluble at physiological pH. Incorporation of these chitosans in the raft monolayers was confirmed in polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS) experiments, where both the tail groups and headgroups were found to interact with chitosan. Since the effects on membrane models may be observed at such small concentrations for chitosans and probably other molecules, some studies may have to be revisited where neat phospholipids should be replaced by lipid raft compositions.

Understanding protein aggregation is essential to unveil molecular mechanisms associated with neurodegenerative diseases such as Alzheimer's, Huntington's and spongiform encephalopathy, particularly to determine the role of interaction with cell membranes. In this study, we employ Langmuir monolayers as cell membrane models to mimic interaction with the peptide KTNMHKHMAGAAAAGAVVGGLG-OH, a fragment from the human prion protein including residues 106-127, believed to be involved in protein aggregation. Using in situ polarization-modulated infrared reflection adsorption spectroscopy (PM-IRRAS) for Langmuir monolayers and FTIR for solid films, we found that PrP106-127 adopts mainly β-sheets, random coils and β-turns in Langmuir monolayers and in Langmuir-Blodgett (LB) and cast films. This also applies to monolayers and solid films made with PrP106-127 and a brain total lipid extract (BTLE). In contrast, some α-helices are observed in the secondary structure of PrP106-127 in monolayers, and especially in solid films, of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC). In summary, in a model representing brain cells (BTLE), the secondary structure of PrP106-127 is typical of fiber aggregates, while aggregation is unlikely if PrP106-127 interacts with a membrane model (DOPC) characteristic of mammalian cells.

Blepharismins are photodynamic hypericin-like dianthrones produced as a variable pigment blend in Blepharisma ciliates and mostly studied in the Afro-Asiatic Blepharisma japonicum. The present work describes the bioactivity of pigments from the Brazilian Blepharisma sinuosum. Comparative analyses showed that the pigments from both species can trigger photo-induced modifications in phospholipids, but different redox properties and biological activities were assigned for each pigment blend. Stronger activities were detected for B. sinuosum pigments, with the lethal concentration LC50 10 × lower than B. japonicum pigments in light-irradiated tests against Bacillus cereus and less than half for treatments on the human HeLa tumor cells. HPLC showed B. sinuosum producing a simpler pigment blend, mostly with the blepharismin-C (~ 70%) and blepharismin-E (~ 30%) types. Each blepharismin engaged a specific dose-response profile on sensitive cells. The blepharismin-B and blepharismin-C were the most toxic pigments, showing LC50 ~ 2.5-3.0 µm and ~ 100 µm on B. cereus and HeLa cells, respectively, after illumination. Similarity clustering analysis compiling the bioactivity data revealed two groups of blepharismins: the most active, B and C, and the less active, A, D and E. The B. sinuosum pigment blend includes one representative of each clade. Functional and medical implications are discussed.

Multidimensional electrochemical and optical sensors hold great potential for screening analysis purposes due to their ability to provide discriminatory chemical analyses without specific receptors for each analyte of interest. Upon exploiting nanomaterials and microfluidic platforms, these sensors have reached high performance in terms of pattern recognition, sensitivity, low consumption of chemicals and samples, repeatability, and analysis time. In this chapter, we discuss recent progress in the design of electrochemical and optical multidimensional arrays and propose a systematic classification of these sensors. Significant issues addressed with the use of nanomaterials (e.g., graphene, nanoparticles, and nanodots) and examples of microfluidic platforms, along with a current outlook for the field, are also discussed.

Made available in DSpace on 2020-12-10T19:54:18Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-04-01 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) National Institute for Science and Technology on Organic Electronics(INEO) Multiple Sclerosis (MS) is a chronic inflammatory disorder in the central nervous system for which biomarkers for diagnosis still remain unknown. One potential biomarker is the myelin basic protein. Here, a nanoimmunosensor based on atomic force spectroscopy (AFS) successfully detected autoantibodies against the MBP85-99 peptide from myelin basic protein. The nanoimmunosensor consisted of an atomic force microscope tip functionalization with MBP85-99 peptide, which was made to interact with a mica surface coated either with a layer of anti-MBP85-99 (positive control) or samples of cerebrospinal fluid (CSF) from five multiple sclerosis (MS) patients at different stages of the disease and five non-MS subjects. The adhesion forces obtained from AFS pointed to a high concentration of anti-MBP85-99 for the two patients at early stages of relapsing-remitting multiple sclerosis (RRMS), which were indistinguishable from the positive control. In contrast, considerably lower adhesion forces were measured for all the other eight subjects, including three MS patients with longer history of the disease and under treatment, without episodes of acute MS activity. We have also shown that the average adhesion force between MBP85-99 and anti-MBP85-99 is compatible with the value estimated using steered molecular dynamics. Though further tests will be required with a larger cohort of patients, the present results indicate that the nanoimmunosensor may be a simple tool to detect early-stage MS patients and be useful to understand the molecular mechanisms behind MS. Univ Fed Sao Carlos, Dept Phys Chem & Math, Nanoneurobiophys Res Grp, BR-18052780 Sorocaba, SP, Brazil Univ Sao Paulo, Inst Trop Med, BR-05403000 Sao Paulo, SP, Brazil Sao Paulo State Univ, Dept Neurol Psychol & Psychiat, BR-18618687 Botucatu, SP, Brazil Univ Sao Paulo, Sao Carlos Inst Phys, BR-13560970 Sao Carlos, SP, Brazil Univ Sao Paulo, Inst Chem, Dept Biochem, BR-05508000 Sao Paulo, SP, Brazil Rheabiotech Lab Res & Dev, BR-13084791 Campinas, SP, Brazil Pontifical Catholic Univ Sao Paulo, BR-18030010 Sorocaba, SP, Brazil Sao Paulo State Univ, Dept Neurol Psychol & Psychiat, BR-18618687 Botucatu, SP, Brazil FAPESP: 2013/14262-7 FAPESP: 2014/21530-0 FAPESP: 2015/14360-4 FAPESP: 2015/06847-0 FAPESP: 2015/36143-2 FAPESP: 2015/052836 FAPESP: 2014/12082-4 FAPESP: 2012/50839-4 FAPESP: 2014/50869-6 CNPq: 465572/2014-6 CNPq: 308658/2015-9 CNPq: 459768/2014-0 CAPES: 23038.000776/201754

Calixarenes are macrocyclic compounds containing a central cavity which can be easily synthesized through various chemical procedures. The presence of the cavity means that they can reversibly form host–guest compounds with inorganic gases and organic vapors. Calixarenes can be obtained in varied sizes and be easily chemically modified with functional groups. This makes them especially suitable as selective sensing molecules due to the ability to fine-tune their structure, cavity size, and functionality. They are highly stable and amenable to processing into thin films using several techniques. Their porous structure allows for rapid diffusion within the films, serving as receptors for binding of gaseous species. In this chapter, we will highlight the use of calixarenes in sensor devices with various principles of detection, including surface plasmon resonance (SPR), surface acoustic wave (SAW), quartz crystal microbalance (QCM), and fiber-optic-based interrogation methods. The combination of stable selective receptors with sensing platforms has enabled sensitive, selective, and reliable detection and monitoring of hazardous gases and vapors.

Rapid, on-site detection of emerging pollutants is critical for monitoring health threats and the environment, especially if performed through autonomous systems. In this paper, we report on a new design of a complete electrochemical system whose working (WE), auxiliary (AE) and reference (RE) electrodes were obtained on a pen (PEN Sensor) made with graphite:polyurethane (GPUE). Working electrodes were decorated with spherical, ca. 200 nm silver nanoparticles (AgNPs) reduced on graphite using the polyol method. Differential pulse voltammetry (DPV) was used to detect bisphenol-A (BPA) in a linear range from 2.5 to 15 μmol L−1 with detection limit of 0.24 μmol L−1. The PEN Sensor could also detect bisphenol-A in tap and river water samples, with satisfactory reproducibility and repeatability, while common interferents did not affect electrooxidation of bisphenol-A. The high sensitivity and rapid detection are suitable for real-time analysis and in loco monitoring of emerging pollutants. With their robustness and versatility, PEN Sensors such as those fabricated here may be integrated into futuristic smart robotic systems.

Great efforts have been focused on the rapid development of gas sensors capable of operating at room temperature since the monitoring of air quality has become a major concern for people’s health and well-being. Nanoarchitectonics is a new concept for the fabrication of functional materials by harmonizing methods at the atomic/molecular level and using mostly bottom-up techniques. In this field, carbon allotropes have been intensively explored, more specifically graphene derivatives due to their outstanding mechanical, electrical, and thermal properties. In the drive toward nanoarchitectonics, researchers have designed nanoarchitectures and nanocomposites of graphene derivatives and conductive polymers, utilizing synergistic effects to enhance the conductivity and thereby improve the performance of sensors for gas detection. Within this chapter, we review recent advances on gas sensors based on graphene/polymer composites and their applications toward the monitoring of hazardous gases.

In this paper, we introduce simple procedures not only to enhance the polarized photoluminescence (PL) of poly(9,9-di-n-octylfluorenyl-2,7-diyl) (PFO) films but also to vary the relative concentrat...

There has been growing interest in using strong field enhancement and light localization in plasmonic nanostructures to control the polarization properties of light. Various experimental techniques are now used to fabricate twisted metallic nanoparticles and metasurfaces, where strongly enhanced chiral near-fields are used to intensify circular dichroism (CD) signals. In this review, state-of-the-art strategies to develop such chiral plasmonic nanoparticles and metasurfaces are summarized, with emphasis on the most recent trends for the design and development of functionalizable surfaces. The major objective is to perform enantiomer selection which is relevant in pharmaceutical applications and for biosensing. Enhanced sensing capabilities are key for the design and manufacture of lab-on-a-chip devices, commonly named point-of-care biosensing devices, which are promising for next-generation healthcare systems.

We demonstrate a giant enhancement of the transverse magneto-optical Kerr effect. In contrast to conventional magnetoplasmonic structures, we exploit surface plasmon resonances (SPRs) excited along the surface of a ferromagnetic substrate on which a uniaxial $\ensuremath{\varepsilon}$-near-zero (ENZ) metamaterial is grown. In this design, bulky prism couplers are not required and SPR sensors can be produced in integrated, miniaturized systems. We also obtained the analytical expression for the ENZ-SPR phase-matching condition, which can be used for the straightforward design of plasmonic and magnetoplasmonic devices.

DNA methylation is involved in the oncogenesis of head and neck squamous cell carcinoma and could be used for early detection of cancer to increase the chances of cure, but unfortunately diagnosis is usually made at late stages of the disease. In this work we developed genosensors to detect DNA methylation of the MGMT gene in head and neck cancer cell lines. The probe for MGMT promoter methylation was immobilized on gold electrodes modified with 11-mercaptoundecanoic acid (11-MUA) self-assembled monolayers (SAM). Detection was performed with electrochemical impedance spectroscopy, with clear distinction between methylated and non-methylated DNA from head and neck cell lines. The genosensor is sensitive with a low detection limit of 0.24 × 10−12 mol L−1. In addition, the cell lines FaDu, JHU28 and SCC25 for the MGMT gene, could be distinguished from the HN13 cell line which has a high degree of MGMT methylation (97%), thus confirming the selectivity. Samples with different percentages of MGMT DNA methylation could be separated in multidimensional projections using the visualization technique interactive document mapping (IDMAP). The genosensor matrix and the immobilization procedures are generic, and can be extended to other DNA methylation biomarkers.

A disposable electrochemical immunosensors is presented suitable to detect cancer biomarker p53 using screen-printed carbon electrodes modified with a layer-by-layer (LbL) matrix of carboxylated NiFe2O4 nanoparticles and polyethyleneimine, onto which anti-p53 antibodies were adsorbed. Under optimized conditions, the immunosensors exhibited high surface coverage and high concentration of immobilized antibodies, which allowed for detection of p53 in a wide dynamic range from 1.0 to 10 × 103 pg mL−1, with a limit of detection of 5.0 fg mL−1 at a working potential of 100 mV vs. Ag/AgCl. The immunosensors also exhibited good selectivity with negligible interference upon incubation in complex matrices containing high concentrations of proteins (i.e., fetal bovine serum and cell lysate). The immunosensor performance is among the best reported in the literature for determination of p53, with the additional advantage of being disposable and operating with low-volume solutions. Graphical abstract

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

The molecular control in Langmuir-Blodgett (LB) films may be exploited in charge storage electrodes provided a suitable choice of molecular architecture and components is made. In this paper, we employed a naphtyl-1,3,4-oxadiazole amphiphile (NFT1) and its complex [Ru(bpy)2NFT1]PF6 (RuNFT1) (bpy = 2,2’-bipyridine) in heterostructured LB films in a proof-of-principle production of charge storage. The optimized architecture contained a one-layer RuNFT1 deposited on a 9-layer NFT1 LB film, where the efficient packing of NFT1 inferred from spectroscopic measurements and Brewster angle microscopy (BAM) images was considered as relevant for ion diffusion. This packing was achieved owing to the π-stacking warranted by the planarity of the NFT1 naphtyl 1,3,4-oxadiazole ring, as confirmed with density functional theory (DFT) calculations. The top layer of the redox-active RuNFT1 provided an additional contribution with its Faradaic charge storage to the double layer capacitance of NFT1. Taken together, these results demonstrate that synergy may be achieved in combining distinct compounds in LB films toward efficient charge storage.

Glutathione-s-transferase is believed to be involved in the resistance to chemotherapeutic drugs, which depends on the interaction with the cell membranes. In this study, we employed Langmuir monolayers of a mixture of phospholipids and cholesterol (MIX) as models for tumor cell membranes and investigated their interaction with the anticancer drugs cisplatin (CDDP) and doxorubicin (DOX). We found that both DOX and CDDP expand and affect the elasticity of MIX monolayers, but these effects are hindered when glutathione-s-transferase (GST) and its cofactor glutathione (GSH) are incorporated. Changes are induced by DOX or CDDP on the polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS) data for MIX/GST/GSH monolayers, thus denoting some degree of interaction that is not sufficient to alter the monolayer mechanical properties. Overall, the results presented here give support to the hypothesis of the inactivation of DOX and CDDP by GST and point to possible directions to detect and fight drug resistance.

Made available in DSpace on 2020-12-12T01:08:30Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-12-24 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) The alarming increase in bacterial resistance to antibiotics has demanded new strategies for microbial inactivation, which include photodynamic therapy whose activity relies on the photoreaction damage to the microorganism membrane. Herein, the binding mechanisms of the photosensitizer toluidine blue-O (TBO) on simplified models of bacterial membrane with Langmuir monolayers of 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) and 1,2-dioleoyl-sn-glycero-3-phospho-(1′-rac-glycerol) (DOPG) were correlated to the effects of the photoinduced lipid oxidation. Langmuir monolayers of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) were also used as a reference of mammalian membranes. The surface pressure isotherms combined with polarization-modulated infrared reflection absorption spectroscopy revealed that TBO expands DOPC, DOPE, and DOPG monolayers owing to electrostatic interactions with the negatively charged groups in the phospholipids, with a stronger adsorption on DOPG, which has a net surface charge. Light irradiation made the TBO-containing DOPC and DOPE monolayers less unstable as a result of the singlet oxygen (1O2) reaction with the chain unsaturation and hydroperoxide formation. In contrast, the decreased stability of the irradiated TBO-containing DOPG monolayer suggests the cleavage of carbon chains. The anionic nature of DOPG allowed a deeper penetration of TBO into the chain region, favoring contact-dependent reactions between the excited triplet state of TBO and lipid unsaturations or/and hydroperoxide groups, which is the key for the cleavage reactions and further membrane permeabilization. São Paulo State University (UNESP) School of Sciences Humanities and Languages IFSC São Carlos Institute of Physics University of São Paulo (USP) São Paulo State University (UNESP) School of Sciences Humanities and Languages

Diagnosis of prostate cancer via PCA3 biomarker detection is promising to be much more efficient than with the prostatic specific antigens currently used. In this study, we present the first electrochemical and impedance-based biosensors that are capable of detecting PCA3 down to 0.128 nmol/L. The biosensors were made with a layer of PCA3-complementary single-stranded DNA (ssDNA) probe, immobilized on a layer-by-layer (LbL) film of chitosan (CHT) and carbon nanotubes (MWCNT). They are highly selective to PCA3, which was confirmed in impedance measurements and with polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS). Using information visualization methods, we could also distinguish between cell lines expressing the endogenous PCA3 long noncoding RNA (lncRNA) from cells that did not contain detectable levels of this biomarker. Since the methods involved in fabrication the biosensors are potentially low cost, one may hope to deploy PCA3 tests in any laboratory of clinical analyses and even for point-of-care diagnostics., This work had financial support from CNPq (Grant #164356/2015-0 and #113757/2018-2), FAPESP (Grant #2013/14262-7) and Barretos Cancer Hospital (Brazil). Andrey Soares thanks to Grant #2018/18953-8, São Paulo Research Foundation (FAPESP). The authors are also thankful to Maria Helena de Oliveira Piazzetta and Angelo Luiz Gobbi for the use of the Microfabrication Laboratory (LMF/LNNano/CNPEM) to manufacture interdigitated electrodes.

In this study, a magnetically separable three-dimensional (3D) Co3[Co(CN)6]2/Fe3O4 nanocomposite comprising magnetic nanoparticles (NPs) adsorbed on the nanocubes of a cobalt Prussian blue analogue was prepared. The nanocomposite exhibited enhanced electrochemical performance in Co2+/Co3+ conversion, while the superparamagnetic behavior of the magnetite NPs was preserved even after adsorption on the nanocubes. Increased Faradaic currents were observed in the cyclic voltammograms (CV) for Co3[Co(CN)6]2/Fe3O4 in comparison with the CV of isolated Co3[Co(CN)6]2. This increase was attributed to supramolecular charge transfer between the cobalt Prussian blue analogue and the magnetic NPs and the larger amount of electroactive species on the electrode. Transmission electron microscopy images showed well-defined Co3[Co(CN)6]2 nanocubes that had edge lengths of 21–140 nm and were decorated with spherical magnetite NPs less than 10 nm in diameter. Interestingly, an intimate contact between the nanocubes and aggreg...

Made available in DSpace on 2018-11-26T22:38:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-07-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) FACEPE Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Antimicrobial peptides (AMPs) are alternatives to conventional antibiotics against multi-drug resistant bacteria with low potential for developing microbial resistance. The design of such molecules requires understanding of the mechanisms of action, particularly the interaction with bacteria cell membranes. In this work, we determine the mechanism responsible for the higher activity against Escherichia coil of the C-terminal lysine dimer of magainin 2, (MG2)(2)K, in comparison to the monomeric peptide magainin 2 (MG2). Langmuir monolayers and vesicles made with the E. coli lipid extract were used to address the two possible states for the peptide-membrane interaction, namely the binding state and pore state, respectively. The incorporation of MG2 and (MG2)(2)K in lipid monolayers at the air-water interface caused slight differences in surface pressure isotherms and polarization-modulated infrared reflection absorption (PM-IRRAS) spectra, and therefore the difference in activity is not associated with the binding state. In contrast, large differences were observed in the leakage experiments where (MG2)(2)K was shown to disrupt the large unilamellar vesicles to a much higher extent owing to efficient pore formation. The binding and penetration of MG2 and (MG2)(2)K were also probed with molecular dynamics (MD) simulations for bilayers made with 1-palmitoy1-2-oleoyl-sn-g/ycero-3-phosphoethanolamine:1-palmitoy1-2-oleoyl-snglycero-3-phosphoglycerol (POPE:POPG). (MG2)(2)K forms disordered toroidal pores at a significant lower concentration than for MG2. In summary, the combination of experimental and computational simulation results indicated that the pre-assembling state of (MG2)(2)K dimer leads to a reduced number of molecules and shorter time being required to kill E. coli. (C) 2018 Elsevier B.V. All rights reserved. Univ Sao Paulo, Inst Fis Sao Carlos, Sao Carlos, SP, Brazil Univ Fed Sao Paulo, Inst Ciencias Ambientais Quim & Farmaceut, Diadema, SP, Brazil Univ Estadual Paulista, Inst Quim, Araraquara, SP, Brazil Univ Fed Pernambuco, Dept Quim Fundamental, Recife, PE, Brazil Univ Fed Goias, Inst Ciencias Biol, Dept Bioquim & Biol Mol, ICB 2 Sala 118,Campus 2 Samambaia, BR-74690900 Goiania, Go, Brazil Univ Estadual Paulista, Inst Quim, Araraquara, SP, Brazil FAPESP: 2013/07600-3 FAPESP: 2013/14262-7 FAPESP: 2015/16857-3 FACEPE: APQ-0732-1.06/14 CAPES: BioComp 23038.004630/2014-35

We report on immunosensors to detect D-dimer, a biomarker of venous thromboembolism, which are made with layer-by-layer (LbL) films containing immobilized anti-D-dimer monoclonal antibody alternated with a layer of chitosan/gold nanoparticles (AuNpChi). Detection was due to irreversible adsorption of the antigen D-dimer on its corresponding antibody according to a Langmuir-Freundlich model, thus giving rise to ellipsoidal structures in scanning electron microscopy images whose size and number increased with D-dimer concentration. The chemical groups involved in the adsorption process were inferred from polarization-modulated infrared reflection absorption (PM-IRRAS) through changes in the amide and carbonyl bands. Detection of D-dimer was made with electrical impedance spectroscopy, electrochemical impedance spectroscopy and cyclic voltammetry. The latter was the most sensitive with a detection limit of 9 × 10−4 µg/mL, sensitivity of 0.27 × 10−6 A/µgmL−1 with linear increase from 0 to 1 µg/mL. The selecti...

A green approach for the preparation of carbon black (CB) and electrochemically reduced graphene oxide composite (ERGO) is described based on screen printed carbon electrodes (SPCEs) fabricated on poly(ethylene terephthalate) (PET) as electrochemical sensors. This approach leads to a heterogeneous hydrophilic surface with high concentration of defect sites according to scanning electron microscopy, contact angle and Raman spectroscopy measurements. The SPCE/CB-ERGO sensor was tested with dopamine (DA), epinephrine (EP) and paracetamol (PCM), exhibiting an enhanced electrocatalytic performance compared to the bare SPCE. It displayed a wider linear range, lower limit of detection and a remarkably higher analytical sensitivity, viz. 1.5, 0.13 and 0.028 A L mol−1 for DA, EP and PCM, respectively, being also capable of simultaneous determination of the three analytes. Such high performance is demonstration that SPCE/CB-ERGO may serve as generic platform for cost-effective flexible electrochemical sensors.

Made available in DSpace on 2018-11-26T17:44:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-03-01 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) The need to improve the sensitivity, selectivity and stability of ozone gas sensors capable of monitoring the environment to prevent hazard to humans has sparked research on binary metal oxides. Here we report on a novel ozone gas sensor made with ca. 0.5 mu m yolk-shelled ZnCo2O4 microstructures synthesized via an eco-friendly, co-precipitation method and subsequent annealing. With these ZnCo2O4 microspheres, ozone concentrations down to 80 parts per billion (ppb) could be detected with a.c. and d.c. electrical measurements. The sensor worked within a wide range of ozone concentrations, from 80 to 890 ppb, being also selective to ozone compared to CO, NH3 and NO2. The high performance could be attributed to the large surface area to volume ratio inherent in yolk-shell structures. Indeed, ozone molecules adsorbed on the ZnCo2O4 surface create a layer of holes that affect the conductivity, as in a p-type semiconductor. Since this mechanism of detection is generic, ZnCo2O4 microspheres can be further used in other environment monitoring devices. (c) 2017 Elsevier B.V. All rights reserved. Univ Sao Paulo, Sao Carlos Inst Phys, CP 369, BR-13560970 Sao Carlos, SP, Brazil Univ Calif Berkeley, Dept Mech Engn, Berkeley, CA 94720 USA Univ Fed Sao Carlos, Dept Phys, Rodovia Washington Luis Km 235, BR-13565905 Sao Carlos, SP, Brazil Myongji Univ, Dept Energy Sci & Technol, Yongin, South Korea Sao Paulo State Univ, Inst Chem, Dept Phys Chem, POB 355, BR-14800900 Araraquara, SP, Brazil Sao Paulo State Univ, Inst Chem, Dept Phys Chem, POB 355, BR-14800900 Araraquara, SP, Brazil FAPESP: 2012/15543-7 FAPESP: 2013/14262-7 FAPESP: 2013/07296-2 FAPESP: 2014/23546-1 FAPESP: 2016/23474-6

This paper describes the synthesis of organically-modified silicates (ormosils) with phosphomolybic acid (HPMo), and their use to detect ametryn. Gold electrodes coated with an ormosil film made of 3-cyanopropyltriethoxysilane (CPTS) and HPMo were used to detect ametryn between 3.5 and 24 µmol L−1 in an acidic medium. There was no evidence of electroreduction of ametryn when ormosils with HPMo and (3-glycidyloxypropyl)trimethoxysilane (GLPTS) or 3-aminopropyltriethoxysilane (APTS) were used. This difference in behavior is ascribed to aggregation in CPTS ormosil, while GLPTS and APTS ormosils displayed homogeneous surfaces, according to scanning electron microscopy. HPMo had its structure preserved in CPTS ormosil as indicated by 31P solid-state nuclear magnetic resonance spectra. Using polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS), we inferred that the functional group dipole moments in all ormosils are oriented parallel to the interface. Control of morphology thus seems essential for applications of ormosil films, being particularly promising to monitor environmentally-relevant herbicides.

We report on a facile strategy for separating carbon spherical shells (CSS) using centrifugation, with which shells were produced with diameter varying from 400 to 500 nm according to scanning and transmission electron microscopies. The shells were made of 79% carbon and 21% oxygen, and their surface was functionalized with carbonyl and hydroxyl groups. The CSS could form a homogeneous film on a glassy carbon (GC) electrode surface and be used in a sensing platform. In electroanalytical experiments, the sensitivity of the GC/CSS electrode for paracetamol increased with decreasing size of CSS. For 400 nm CSS, the sensitivity was 0.02 μA μmol–1 L, and the limit of detection and quantification in sweat, saliva, and urine samples was 120 and 400, 286 and 470, and 584 and 530 nmol L–1, respectively, which represents the highest performance among carbon-based sensors found in the literature. The GC/CSS electrodes were stable, robust against typical interferents, and allowed detection of paracetamol in sweat, sa...

In this study, we show the synthesis of novel hybrid organic-inorganic aerogel materials with one-dimensionally aligned pores and demonstrate their use as sustained and prolonged release systems for a hydrophobic drug. The materials are synthesized by trapping mesoporous silica nanoparticles within a hyperbranched polymer network made from poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAA). The synthetic method involves dispersing mesoporous silica nanoparticles in a polymer solution, then freeze-drying the solution, and finally subjecting the resulting materials to high temperature to activate a solid-state condensation reaction between PVA and PAA. Before trapping the mesoporous silica nanoparticles within the hyperbranched polymeric network, their pores are decorated with hydrophobic groups so that they can serve as good host materials for hydrophobic drugs. The potential application of the hybrid aerogels as drug carriers is demonstrated using the hydrophobic, anti-inflammatory agent dexamethasone (DEX) as a model drug. Due to their hydrophobic pores, the hybrid aerogels show excellent drug loading capacity for DEX, with an encapsulation efficiency higher than 75%. Furthermore, the release pattern of the payloads of DEX encapsulated in the aerogels is highly tailorable (i.e., it can be made faster or slower, as needed) simply by varying the PVA-to-PAA weight ratio in the precursors, and thus the 3-dimensional (3-D) structures of the cross-linked polymers in them. The materials also show sustained drug release, for over 50 days or more. In addition, the aerogels are biocompatible, as demonstrated with Vero cells, and greatly promote the cell proliferation of L929 fibroblasts. Also, the nanoparticles functionalized with quaternary groups and dispersed within the aerogels display bactericidal activity against E. coli, S. aureus, B. subtilis, and P. aeruginosa. These new hybrid aerogels can, thus, be highly appealing biomaterials for sustained and prolonged drug release, such as wound dressing systems.

In this paper we present a portable photoelectrochemical system developed with screen-printed carbon electrodes (SPCEs) and a 3 W light-emitting diode (LED). The device with 3D printed structure was applied for detecting lactate on TiO2 nanoparticles modified with [Ni(salen)] polymer film (referred to as TiO2@poly[Ni(salen)]). Electrode coating with the polymer increased the sensitivity of the photoelectrochemical sensor, resulting in a linear range from 0.1 to 20 mmol L−1 with a limit of detection (LOD) of 88 μmol L−1. The sensing system exhibited excellent stability, reproducibility, and selectivity. We also demonstrated by in situ Fourier-transform infrared spectroscopy (FTIR) measurements that carbon dioxide (CO2) is the main product from photoelectrooxidation of lactate on TiO2@poly[Ni(salen)]. The portable system can be employed with any type of modified electrodes to function as photoelectroanalytical (bio)sensors, especially for point-of-care diagnostics.

Made available in DSpace on 2018-12-11T17:33:19Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-10-01 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) The persistence of steroid hormones disposed of in the environment may pose risks to the health of humans and wildlife, which brings the need of understanding their mode of action, believed to occur in cell membranes. In this study, we investigate the molecular-level interactions between the synthetic hormone 17 α-ethynylestradiol (EE2) and Langmuir monolayers that represent simplified cell membranes. In surface pressure isotherms, EE2 was found to expand the monolayers at low surface pressures of the positively charged dimethyldioctadecylammonium bromide (DODAB), zwitterionic 1,2-dipalmitoyl-sn-glycerol-3-phosphocholine (DPPC), negatively charged 1,2-dipalmitoyl-sn-glycero-3-phosphoglycerol (DPPG), and partially anionized stearic acid (StAc). The largest effects were observed for the charged DODAB and DPPG. At the pressure (30 mN.m−1) corresponding to the molecular packing of a cell membrane, EE2 caused the compressibility modulus to decrease, again with the largest changes occurring for DODAB and DPPG. The effects from EE2 on the packing of the lipid molecules at this high pressure depended essentially on the size of the headgroups, with EE2 contributing to the area per lipid for StAc and DODAB, whose headgroups are small. EE2 interacted with the headgroups of all lipids and StAc, also affecting the ordering of the tails for DODAB, DPPG and DPPC, according to in situ polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS). Based on the analysis with the two characterization methods, we propose a model for the EE2 positioning and molecular groups involved in the interaction, which should be relevant to unveil the endocrine disrupting action of EE2. São Paulo State University (UNESP) School of Technology and Applied Sciences São Carlos Institute of Physics − University of São Paulo, CP 369, 13560-970 São Carlos São Paulo State University (UNESP) School of Technology and Applied Sciences