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Lima, Nuno, Ana Catarina Baptista, Bruno Morais M. Faustino, Sofia Taborda, Ana Marques, and Isabel Ferreira. "Carbon threads sweat-based supercapacitors for electronic textiles." Scientific Reports 10 (2020): 7703. AbstractWebsite

Flexible and stretchable energy-storage batteries and supercapacitors suitable for wearable electronics are at the forefront of the emerging field of intelligent textiles. In this context, the work here presented reports on the development of a symmetrical wire-based supercapacitor able to use the wearer’s sweat as the electrolyte. The inner and outer electrodes consists of a carbon-based thread functionalized with a conductive polymer (polypyrrole) which improves the electrochemical performances of the supercapacitor. The inner electrode is coated with electrospun cellulose acetate fibres, as the separator, and the outer electrode is twisted around it. The electrochemical performances of carbon-based supercapacitors were analyzed using a simulated sweat solution and displayed a specific capacitance of 2.3 F.g−1, an energy of 386.5 mWh.kg−1 and a power density of 46.4 kW.kg−1. Moreover, cycle stability and bendability studies were performed. Such energy conversion device has exhibited a stable electrochemical performance under mechanical deformation, over than 1000 cycles, which make it attractive for wearable electronics. Finally, four devices were tested by combining two supercapacitors in series with two in parallel demonstrating the ability to power a LED.

Ropio, Inês, Ana Catarina Baptista, Joana Nobre, J. Correia, F. Belo, S. Taborda, Morais B. M. Faustino, João Borges Borges, A. Kovalenko, and Isabel Ferreira. "Cellulose paper functionalised with polypyrrole and poly(3,4-ethylenedioxythiophene) for paper battery electrodes." Organic Electronics 62 (2018): 530-535. AbstractWebsite

A simple process of commercial paper functionalisation via in situ polymerisation of conductive polymers onto cellulose fibres was investigated and applied as electrodes in paper-based batteries. The functionalisation involved polypyrrole (PPy) and Poly (3,4-ethylenedioxythiophene) (PEDOT) as conductive polymers with the process of functionalisation optimised for each polymer individually with respect to oxidant-to-monomer ratios and polymerisation times and temperature. Paper with conductivity values of 44 mS/cm was obtained by exposing the samples to pyrrole vapour for a period of 30 min at room temperature; however, polymerisation at temperatures of 40 °C lead to higher conductivity values to up 141 mS/cm. Consequently, functionalised PPy and PEDOT papers were applied as cathodes in batteries with Al foil anodes and commercial paper soaked in an electrolyte solution of NaCl.

Borges, João Paulo, Maria Helena Godinho, Assis Farinha Martins, Ana Catarina Trindade, and Mohamed Naceur Belgacem. "Cellulose-based composite films." Mechanics of composite materials 37 (2001): 257-264. AbstractWebsite

The mechanical and optical properties of cellulose-based composite films are investigated.It is shown that the use of toluene diisocyanate as a coupling agent and Avicel fibers as reinforcing elements give films with the highest mechanical characteristics. Using differential scanning calorimetry, it is also found that the glass transition temperature Tg of all the materials studied is below the room temperature and that the Tg increased with cross-linking and introduction of Avicel.

Baptista, Ana Catarina, Isabel Ferreira, and João Paulo Borges. "Cellulose-based composite systems for biomedical applications." In Biomass based Biocomposites, edited by Vijay Kumar Thakur and A. S. Singha, 47-60. U.K.: Smithers Rapra Technology, 2013.
Borges, João Paulo, João Paulo Canejo, Susete Fernandes, Pedro Brogueira, and Maria Helena Godinho. "Cellulose-Based Liquid Crystalline Composite Systems." In Nanocellulose Polymer Nanocomposites: Fundamentals and Applications, edited by Vijay Kumar Thakur, 215-235. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2014.
João, Carlos, Jorge Carvalho Silva, and João Paulo Borges. "Chitin-Based Nanocomposites: Biomedical Applications." In Eco-friendly Polymer Nanocomposites, edited by Vijay Kumar Thakur and Manju Kumari Thakur, 439-457. Springer India, 2015. Abstract

Chitin, the second most abundant polymer in nature, is a renewable, nontoxic, biodegradable, and antibacterial polysaccharide. This semicrystalline biopolymer exhibits hierarchical structure from nano to micro-scale and is responsible for interesting living tissue properties. Recently, the scientific interest in chitin nanofibrils for applications in biomedical and tissue engineering fields has increased due to their particular capabilities such as matrix reinforcements, bioactivity and morphology similar to natural tissues. This chapter is focused on composite materials reinforced with chitin nanofibrils and their biomedical applications.

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Strohmeier, P., C. Honnet, H. Perner-Wilson, M. Teyssier, B. Fruchard, Ana Catarina Baptista, and J. Steimle. Demo of PolySense: How to Make Electrically Functional Textiles In CHI Conference on Human Factors in Computing Systems., 2020. Abstract

We demonstrate a simple and accessible method for enhancing textiles with custom piezo-resistive properties. Based on in-situ polymerization, our method offers seamless integration at the material level, preserving a textile's haptic and mechanical properties. We demonstrate how to enhance a wide set of fabrics and yarns using only readily available tools. During each demo session, conference attendees may bring textile samples which will be polymerized in a shared batch. Attendees may keep these samples. While the polymerization is happening, attendees can inspect pre-made samples and explore how these might be integrated in functional circuits. Examples objects created using polymerization include rapid manufacturing of on-body interfaces, tie-dyed motion-capture clothing, and zippers that act as potentiometers.

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Canejo, João Paulo, João Paulo Borges, Maria Helena Godinho, Pedro Brogueira, Paulo IC Teixeira, and Eugene M. Terentjev. "Helical Twisting of Electrospun Liquid Crystalline Cellulose Micro-and Nanofibers." Advanced Materials 20 (2008): 4821-4825. AbstractWebsite

Helically twisted fibers can be produced by electrospinning liquid-crystalline cellulose solutions. Fiber topographies are studied by atomic force microscopy, scanning electron microscopy (see figure) and polarized optical microscopy. The fibers have a nearly universal pitch-to-diameter ratio and comprise both right- and left-handed helices.

Godinho, Maria Helena, João Paulo Canejo, Luis FV Pinto, João Paulo Borges, and Paulo IC Teixeira. "How to mimic the shapes of plant tendrils on the nano and microscale: spirals and helices of electrospun liquid crystalline cellulose derivatives." Soft Matter 5 (2009): 2772-2776. AbstractWebsite

We show that suspended nano and microfibres electrospun from liquid crystalline cellulosic solutions will curl into spirals if they are supported at just one end, or, if they are supported at both ends, will twist into a helix of one handedness over half of its length and of the opposite handedness over the other half, the two halves being connected by a short straight section. This latter phenomenon, known as perversion, is a consequence of the intrinsic curvature of the fibres and of a topological conservation law. Furthermore, agreement between theory and experiment can only be achieved if account is taken of the intrinsic torsion of the fibres. Precisely the same behaviour is known to be exhibited by the tendrils of climbing plants such as Passiflora edulis, albeit on a lengthscale of millimetres, i.e., three to four orders of magnitude larger than in our fibres. This suggests that the same basic, coarse-grained physical model is applicable across a range of lengthscales.

Soares, Paula I. P., Coro Echeverria, Ana Catarina Baptista, Carlos João, Susete Fernandes, Ana Almeida, Jorge Carvalho Silva, Maria Helena Godinho, and João Paulo Borges. "Hybrid polysaccharide-based systems for biomedical applications." In Hybrid Polymer Composite Materials: Applications, edited by Manju Kumari Thakur, Vijay Kumar Thakur and Asokan Pappu, 107-149. USA: Woodhead Publishing, Elsevier, 2017. Abstract

Hybrid materials have been widely studied for structural applications. Polysaccharide-based fibers, especially cellulosic fibers, have been explored in the last two decades as substitutes of the traditional reinforcements made of glass or carbon fibers due to their mechanical properties. However, their biocompatibility, biodegradability, and chemistry have attracted the researchers and new developments in the field of smart and functional materials arise in diverse applications. This chapter will focus on the biomedical applications of polysaccharide-based smart and functional materials, namely those concerning biosensors and actuators, theranostic systems, and tissue-engineering applications. Special attention will be given to cellulose- and chitin/chitosan-based hybrid materials because these are the two most abundant polysaccharides and probably the most promising for the development of hybrid materials for biomedical applications. Biomimetic strategies for the development of smart and functional hybrid materials will also be highlighted.

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Baptista, Ana Catarina, Paula I. P. Soares, Isabel Ferreira, and João Paulo Borges. "Nanofibers and nanoparticles in biomedical applications." In Bioengineered Nanomaterials, edited by Atul Tiwari and Ashutosh Tiwari. USA: CRC Press (Taylor & Francis Group), 2013.
Graça, Manuel P., Silvia Soreto Teixeira, Sílvia R. Gavinho, Manuel Almeida Valente, Cristiana Salgueiro, José Nunes, Paula I. P. Soares, Maria Carmo Lança, Tânia Vieira, Jorge Carvalho Silva, and João Borges Borges. "Nanomaterials for magnetic hyperthermia." European Journal of Public Health 31 (2021): ckab120.066. AbstractWebsite

Cancer remains as one of the major causes of mortality worldwide. Recent advances in nanoparticles based therapy mark a new era on cancer treatment. Many groups have investigated biological/physical effects of nanoparticles on tumour cells and how these vary with physical parameters such as particle size, shape, concentration and distribution. Magnetic hyperthermia (MHT) can be an alternative or an add-value therapy with demonstrated effectiveness. MHT uses magnetic nanoparticles, which can be directly applied to the tumour, where, by applying an external ac magnetic field, will promote a localized temperature increment that can be controlled.

Teixeira, Silvia Soreto, Manuel P. F. Graça, José Lucas, Manuel Almeida Valente, Paula I. P. Soares, Maria Carmo Lança, Tânia Vieira, Jorge Carvalho Silva, João Paulo Borges, Luiza-Izabela Jinga, Gabriel Socol, Cristiane Mello Salgueiro, José Nunes, and Luís C. Costa. "Nanostructured LiFe5O8 by a Biogenic Method for Applications from Electronics to Medicine." Nanomaterials 11 (2021): 193. AbstractWebsite

The physical properties of the cubic and ferrimagnetic spinel ferrite LiFe5O8 has made it an attractive material for electronic and medical applications. In this work, LiFe5O8 nanosized crystallites were synthesized by a novel and eco-friendly sol-gel process, by using powder coconut water as a mediated reaction medium. The dried powders were heat-treated (HT) at temperatures between 400 and 1000 °C, and their structure, morphology, electrical and magnetic characteristics, cytotoxicity, and magnetic hyperthermia assays were performed. The heat treatment of the LiFe5O8 powder tunes the crystallite sizes between 50 nm and 200 nm. When increasing the temperature of the HT, secondary phases start to form. The dielectric analysis revealed, at 300 K and 10 kHz, an increase of ε′ (≈10 up to ≈14) with a tanδ almost constant (≈0.3) with the increase of the HT temperature. The cytotoxicity results reveal, for concentrations below 2.5 mg/mL, that all samples have a non-cytotoxicity property. The sample heat-treated at 1000 °C, which revealed hysteresis and magnetic saturation of 73 emu g−1 at 300 K, showed a heating profile adequate for magnetic hyperthermia applications, showing the potential for biomedical applications.

Tipa, Cezar, Maria Teresa Cidade, Tânia Vieira, Jorge Carvalho Silva, Paula I. P. Soares, and João Paulo Borges. "A New Long-Term Composite Drug Delivery System Based on Thermo-Responsive Hydrogel and Nanoclay." Nanomaterials 11 (2021): 25. AbstractWebsite

Several problems and limitations faced in the treatment of many diseases can be overcome by using controlled drug delivery systems (DDS), where the active compound is transported to the target site, minimizing undesirable side effects. In situ-forming hydrogels that can be injected as viscous liquids and jellify under physiological conditions and biocompatible clay nanoparticles have been used in DDS development. In this work, polymer–clay composites based on Pluronics (F127 and F68) and nanoclays were developed, aiming at a biocompatible and injectable system for long-term controlled delivery of methylene blue (MB) as a model drug. MB release from the systems produced was carried out at 37 °C in a pH 7.4 medium. The Pluronic formulation selected (F127/F68 18/2 wt.%) displayed a sol/gel transition at approx. 30 °C, needing a 2.5 N force to be injected at 25 °C. The addition of 2 wt.% of Na116 clay decreased the sol/gel transition to 28 °C and significantly enhanced its viscoelastic modulus. The most suitable DDS for long-term application was the Na116-MB hybrid from which, after 15 days, only 3% of the encapsulated MB was released. The system developed in this work proved to be injectable, with a long-term drug delivery profile up to 45 days.