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Borges, João Paulo, Maria Helena Godinho, Joao Luis Figueirinhas, MN de Pinho, and Mohamed Naceur Belgacem. "All-cellulosic based composites." In Cellulose Fibers: Bio-and Nano-Polymer Composites, edited by Susheel Kalia, B. S. Kaith and Inderjeet Kaur, 399-421. Springer Berlin Heidelberg, 2011. Abstract

The use of cellulosic fibers as load bearing constituents in composite materials has increased over the last decade due to their relative cheapness compared to conventional materials such as glass and aramid fibers, their ability to recycle, and because they compete well in terms of strength per weight of material. All-cellulosic based composites prepared from cellulose derivatives based matrices and microcrystalline cellulosic fibers made by direct coupling between fibers and matrix present interesting mechanical and gas permeation properties, thus being potential candidates for packaging materials. Both the cellulosic matrix and the reinforcing fibers are biocompatible and widely used in the pharmaceutical industry, which is very important for the envisaged application. In addition to their biocompatibility, cellulosic systems have the ability to form both thermotropic and lyotropic chiral nematic phases, and the composites produced from the latter show improved mechanical properties due to fiber orientation induced by the anisotropic matrix. The preparation and characterization (morphological, topographical, mechanical, gas barrier properties) of all-cellulosic based composites are described in this chapter.

Gavinho, Sílvia R., Manuel P. Graça, Pedro Prezas, João Borges Borges, Jorge Carvalho Silva, Eduardo Pires, Henrique Armês, and José Coucelo. "Antibacterial bioglass in dental implants: a canine clinical study." European Journal of Public Health 31 (2021): ckab120.006. AbstractWebsite

Peri-implantitis is considered the most challenging biological complication in implantology, as untreated disease can progress and result in implant loss. Therefore, disease prevention is crucial in daily clinical practice. It has been reported that the use of bioactive glass, as an implant coating, can stimulate tissue integration and accelerate tissue regeneration. Besides these properties, it is possible to promote bacterial activity by inserting silver into the bioglass

Bioglass with composition 45S5 was synthesised by the fusion method, replacing the amount of Na2CO3 by AgNO3 (BG 2% wt). The implants were resealed by the CoBlast® technique. Clinical cases with pathology of the mandible/maxilla were selected and implants dimensioned for the canine bone structure were applied.

Three months after implantation, imaging exams, namely CT scans, showed no signs of early rejection by septic or cytotoxic loss. No decrease or loss of peri-implant bone was observed. In all cases the implants remained without signs of instability, and with sufficient support for the application of the exo-prosthesis or dental crown. The results of histological analysis showed no signs of infection or osteolysis. The zone of peri-implant fibrosis was not observable in the samples, showing a good evolution in implant osteointegration.

The results show promising evidences for the use of this biomaterial as a coating, since aseptic rejection, later on, and that related to the shape and biomaterials used in the implant's design, usually begins during the first 3 months.

Quirós, Jennifer, João Paulo Borges, Karina Boltes, Ismael Rodea-Palomares, and Roberto Rosal. "Antimicrobial electrospun silver-, copper- and zinc-doped polyvinylpyrrolidone nanofibers." Journal of Hazardous Materials 299 (2015): 298-305. AbstractWebsite

The use of electrospun polyvinylpyrrolidone (PVP) nanofibers containing silver, copper, and zinc nanoparticles was studied to prepare antimicrobial mats using silver and copper nitrates and zinc acetate as precursors. Silver became reduced during electrospinning and formed nanoparticles of several tens of nanometers. Silver nanoparticles and the insoluble forms of copper and zinc were dispersed using low molecular weight PVP as capping agent. High molecular weight PVP formed uniform fibers with a narrow distribution of diameters around 500 nm. The fibers were converted into an insoluble network using ultraviolet irradiation crosslinking. The efficiency of metal-loaded mats against the bacteria Escherichia coli and Staphylococcus aureus was tested for different metal loadings by measuring the inhibition of colony forming units and the staining with fluorescent probes for metabolic viability and compromised membranes. The assays included the culture in contact with mats and the direct staining of surface attached microorganisms. The results indicated a strong inhibition for silver-loaded fibers and the absence of significant amounts of viable but non-culturable microorganisms. Copper and zinc-loaded mats also decreased the metabolic activity and cell viability, although in a lesser extent. Metal-loaded fibers allowed the slow release of the soluble forms of the three metals.

Soares, Paula I. P., Isabel Ferreira, and João Paulo Borges. "Application of Hyperthermia for Cancer Treatment: Recent Patents Review." In Topics in Anti-Cancer Research, Vol. 3, edited by Atta-ur-Rahman and Khurshid Zaman, 342-383. Bentham Science Publishers, 2014. Abstract

Cancer is one of the main causes of death in the world and its incidence increases every day. Current treatments are insufficient and present many breaches. Hyperthermia is an old concept and was early established as a cancer treatment option, mainly in superficial cancers. More recently, the concept of intracellular hyperthermia emerged wherein magnetic particles are concentrated at the tumor site and remotely heated using an applied magnetic field to achieve hyperthermic temperatures (42-45ºC). Many patents have been registered in this area since the year 2000. This chapter presents the most relevant information organized in two main categories according to the use or not of nanotechnology. The patents without nanotechnology were divided into the following subcategories: 1) external Radio-Frequency devices; 2) hyperthermic perfusion; 3) frequency enhancers; 4) applying heat to the target site using a catheter; and 5) injection of magnetic and ferroelectric particles. The patents with nanotechnology were divided into three subcategories: 1) hyperthermia devices; 2) nanoparticles; and 3) nanostructures. The use of magnetic nanoparticles is a very promising treatment approach since it may be used for diagnostic and treatment. Magnetic nanoparticle could be applied to detect and diagnose the tumor and to carry a pharmacological active drug to be delivered in the tumor site or apply hyperthermia through an external magnetic field.

Soares, Paula I. P., Isabel Ferreira, Rui Igreja, Carlos Novo, and João Paulo Borges. "Application of Hyperthermia for Cancer Treatment: Recent Patents Review." Recent Patents on Anti-Cancer Drug Discovery 7 (2012): 64-73. AbstractWebsite

Cancer is one of the main causes of death in the world and its incidence increases every day. Current treatments are insufficient and present many breaches. Hyperthermia is an old concept and since early it was established as a cancer treatment option, mainly in superficial cancers. More recently the concept of intracellular hyperthermia emerged wherein magnetic particles are concentrated at the tumor site and remotely heated using an applied magnetic field to achieve hyperthermic temperatures (42-45°C). Many patents have been registered in this area since the year 2000. This review presents the most relevant information, organizing them according to the hyperthermic method used: 1) external Radio- Frequency devices; 2) hyperthermic perfusion; 3) frequency enhancers; 4) apply heating to the target site using a catheter; 5) injection of magnetic and ferroelectric particles; 6) injection of magnetic nanoparticles that may carry a pharmacological active drug. The use of magnetic nanoparticles is a very promising treatment approach since it may be used for diagnostic and treatment. An ideal magnetic nanoparticle would be able to detect and diagnose the tumor, carry a pharmacological active drug to be delivered in the tumor site, apply hyperthermia through an external magnetic field and allow treatment monitoring by magnetic resonance imaging.

João, Carlos, Coro Echeverria, Alexandre Velhinho, Jorge Carvalho Silva, Maria Helena Godinho, and João Paulo Borges. "Bio-inspired production of chitosan/chitin films from liquid crystalline suspensions." Carbohydrate polymers 155 (2017): 372-381. AbstractWebsite

Inspired by chitin based hierarchical structures observed in arthropods exoskeleton, this work reports the capturing of chitin nanowhiskers’ chiral nematic order into a chitosan matrix. For this purpose, highly crystalline chitin nanowhiskers (CTNW) with spindle-like morphology and average aspect ratio of 24.9 were produced by acid hydrolysis of chitin. CTNW were uniformly dispersed at different concentrations in aqueous suspensions. The suspensions liquid crystalline phase domain was determined by rheological measurements and polarized optical microscopy (POM). Chitosan (CS) was added to the CTNW isotropic, biphasic and anisotropic suspensions and the solvent was evaporated to allow films formation. The Films’ morphologies as well as the mechanical properties were explored. A correlation between experimental results and a theoretical model, for layered matrix’ structures with fibers acting as a reinforcement agent, was established. The results evidence the existence of two different layered structures, one formed by chitosan layers induced by the presence of chitin and another formed by chitin nanowhiskers layers. By playing on the ratio chitin/chitosan one layered structure or the other can be obtained allowing the tunning of materials’ mechanical properties.

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 386.5−1 and a power density of 46.4−1. 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.

Faria, Jaime, Bruno Dionísio, Iris Soares, Ana Catarina Baptista, Ana Cláudia Marques, Lídia Gonçalves, Ana Bettencourt, Carlos Baleizão, and Isabel Ferreira. "Cellulose acetate fibres loaded with daptomycin for metal implant coatings." Carbohydrate polymers (2021): 118733. AbstractWebsite

Multifunctional polymeric coatings containing drug delivery vehicles can play a key role in preventing/reducing biofilm formation on implant surfaces. Their requirements are biocompatibility, good adhesion, and controllable drug release. Although cellulose acetate (CA) films and membranes are widely studied for scaffolding, their applications as a protective coating and drug delivery vehicle for metal implants are scarce. The reason is that adhesion to stainless steel (SS) substrates is non-trivial. Grinding SS substrates enhances the adhesion of dip-coated CA films while the adhesion of electrospun CA membranes is improved by an electrosprayed chitosan intermediate layer. PMMA microcapsules containing daptomycin have been successfully incorporated into CA films and fibres. The released drug concentration of 3 x10-3 mg/mL after 120 minutes was confirmed from the peak luminescence intensity under UV radiation of simulated body fluid (SBF) after immersion of the fibres.

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.

Baptista, Ana Catarina, Isabel Ferreira, and João Borges. "Cellulose-based bioelectronic devices." In Cellulose - Medical, Pharmaceutical and Electronic Applications, edited by Theo van de Ven and Louis Godbout. InTech, 2013.
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.
Baptista, Ana Catarina, Inês Ropio, Beatriz Romba, Joana Nobre, Célia Henriques, Jorge Carvalho Silva, J. I. Martins, João Paulo Borges, and Isabel Ferreira. "Cellulose-based electrospun fibers functionalized with polypyrrole and polyaniline for fully organic batteries." Journal of Materials Chemistry A 6 (2018): 256-265. AbstractWebsite

A novel cellulose-based bio-battery made of electrospun fibers activated by biological fluids has been developed. This work reports a new concept for a fully organic bio-battery that takes advantage of the high surface to volume ratio achieved by an electrospun matrix composed of sub-micrometric fibers that acts simultaneously as the separator and the support of the electrodes. Polymer composites of polypyrrole (PPy) and polyaniline (PANI) with cellulose acetate (CA) electrospun matrix were produced by in situ chemical oxidation of pyrrole and aniline on the CA fibers. The structure (CA/PPy|CA|CA/PANI) generated a power density of 1.7 mW g−1 in the presence of simulated biological fluids, which is a new and significant contribution to the domain of medical batteries and fully organic devices for biomedical applications.

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.

João, Carlos, Ana Teresa Kullberg, Jorge Carvalho Silva, and João Paulo Borges. "Chitosan Inverted Colloidal Crystal scaffolds: Influence of molecular weight on structural stability." Materials Letters 193 (2017): 50-53. AbstractWebsite

Chitosan with three different molecular weights (538 ± 48, 229 ± 45 and 13 ± 3 kDa) was used to develop biodegradable Inverted Colloidal Crystal (ICC) scaffolds with uniform pore size and interconnected pore network. Mass loss and compression modulus were analyzed after hydrolytic degradation in order to understand the influence of molecular weight on structural and mechanical degradation of chitosan ICC structures. Results show that medium molecular weight chitosan (229 ± 45 kDa) retains ICC structure and compression modulus for an extended period (4 weeks) and is therefore the preferred one for the production of ICC for soft tissue engineering.

Soares, Paula I. P., Ana Isabel Sousa, Jorge Carvalho Silva, Isabel Ferreira, Carlos Novo, and João Paulo Borges. "Chitosan-based nanoparticles as drug delivery systems for doxorubicin: optimization and modelling." Carbohydrate polymers 147 (2016): 304-312. AbstractWebsite

In the present work, two drug delivery systems were produced by encapsulating doxorubicin into chitosan and O-HTCC (ammonium-quaternary derivative of chitosan) nanoparticles. The results show that doxorubicin release is independent of the molecular weight and is higher at acidic pH (4.5) than at physiological pH. NPs with an average hydrodynamic diameter bellow 200 nm are able to encapsulate up to 70% and 50% of doxorubicin in the case of chitosan and O-HTCC nanoparticles, respectively. O-HTCC nanoparticles led to a higher amount of doxorubicin released than chitosan nanoparticles, for the same experimental conditions, although the release mechanism was not altered. A burst effect occurs within the first hours of release, reaching a plateau after 24 h. Fitting mathematical models to the experimental data led to a concordant release mechanism between most samples, indicating an anomalous or mixed release, which is in agreement with the swelling behavior of chitosan described in the literature.

Zamora-Mora, Vanessa, Paula I. P. Soares, Coro Echeverria, Rebeca Hernández, and Carmen Mijangos. "Composite chitosan/agarose ferrogels for potential applications in magnetic hyperthermia." Gels 1 (2015): 69-80. AbstractWebsite

Composite ferrogels were obtained by encapsulation of magnetic nanoparticles at two different concentrations (2.0 and 5.0 % w/v) within mixed agarose/chitosan hydrogels having different concentrations of agarose (1.0, 1.5 and 2.0% (w/v)) and a fixed concentration of chitosan (0.5% (w/v)). The morphological characterization carried out by scanning electron microscopy showed that dried composite ferrogels present pore sizes in the micrometer range. Thermogravimetric measurements showed that ferrogels present higher degradation temperatures than blank chitosan/agarose hydrogels without magnetic nanoparticles. In addition, measurements of the elastic moduli of the composite ferrogels evidenced that the presence of magnetic nanoparticles in the starting aqueous solutions prevents to some extent the agarose gelation achieved by simply cooling chitosan/agarose aqueous solutions. Finally, it is shown that composite chitosan/agarose ferrogels are able to heat in response to the application of an alternating magnetic field so that they can be considered as potential biomaterials to be employed in magnetic hyperthermia treatments.

Perdigão, Patrícia, Bruno Faustino, Jaime Faria, João Paulo Canejo, João Borges Borges, Isabel Ferreira, and Ana Catarina Baptista. "Conductive Electrospun Polyaniline/Polyvinylpyrrolidone Nanofibers: Electrical and Morphological Characterization of New Yarns for Electronic Textiles." Fibers 8 (2020): 24. AbstractWebsite

Advanced functionalities textiles embedding electronic fibers, yarns and fabrics are a demand for innovative smart cloths. Conductive electrospun membranes and yarns based on polyaniline/polyvinylpyrrolidone (PANI/PVP) were investigated using the chemical modification of PANI instead of using conventional coating processes as in-situ polymerization. PANI was synthesized from the aniline monomer and the influence of the oxidant-to-monomer ratio on electrical conductivity was studied. The optimized conductivity of pellets made with pressed PANI powders was 21 S·cm−1. Yarns were then prepared from the t-Boc-PANI/PVP electrospun membranes followed by PANI protonation to enhance their electrical properties. Using this methodology, electrospun membranes and yarns were produced with electrical conductivities of 1.7 × 10−2 and 4.1 × 10−4 S·cm−1.

Marques, Susana, Paula I. P. Soares, Coro Echeverria, Maria Helena Godinho, and João Paulo Borges. "Confinement of thermoresponsive microgels into fibres via colloidal electrospinning: experimental and statistical analysis." RSC Advances 6 (2016): 76370-76380. AbstractWebsite

The strategy of confining stimuli-responsive microgels in electrospun fibres would allow the fabrication of polymeric networks that combine the microgels swelling ability and properties with the interest features of the electrospun fibres. Colloidal electrospinning is an emerging method in which fibres containing microgels can be produced by a single-nozzle and designed through the solution carrier materials. The incorporation of poly(N-isopropylacrylamide) (PNIPAAM) and PNIPAAM-chitosan (PNIPAAM-CS) in poly(ethyleneoxyde) (PEO) fibres via colloidal electrospinning producing composite fibres was the main purpose of the present work{,} which was confirmed by means of Scanning Electron Microscopy (SEM). Dynamic light scattering was used to analyse the microgels hydrodynamic diameter ranging up to 900 nm depending on the composition and temperature of the surrounding medium. By performing a statistical analysis the relationship of the processing variables over the fibre size was evaluated following the response surface methodology (RSM). From the set of parameters aimed to minimize the fibre diameter{,} composite fibres with an average diameter of 63 nm were produced. Only the as-prepared microgels with higher monodispersity provided {"}bead-on-a-string{"} morphologies.

Cristovão, Ana Filipa, David Sousa, Filipe Silvestre, Inês Ropio, Ana Gaspar, Célia Henriques, Alexandre Velhinho, Ana Catarina Baptista, Miguel Faustino, and Isabel Ferreira. "Customized tracheal design using 3D printing of a polymer hydrogel: influence of UV laser cross-linking on mechanical properties." 3D Printing in Medicine 5 (2019): 12. AbstractWebsite

The use of 3D printing of hydrogels as a cell support in bio-printing of cartilage, organs and tissue has attracted much research interest. For cartilage applications, hydrogels as soft materials must show some degree of rigidity, which can be achieved by photo- or chemical polymerization. In this work, we combined chemical and UV laser polymeric cross-linkage to control the mechanical properties of 3D printed hydrogel blends. Since there are few studies on UV laser cross-linking combined with 3D printing of hydrogels, the work here reported offered many challenges.

Polyethylene glycol diacrylate (PEGDA), sodium alginate (SA) and calcium sulphate (CaSO4) polymer paste containing riboflavin (vitamin B2) and triethanolamine (TEOHA) as a biocompatible photoinitiator was printed in an extrusion 3D plotter using a coupled UV laser. The influence of the laser power on the mechanical properties of the printed samples was then examined in unconfined compression stress-strain tests of 1 × 1 × 1 cm3 sized samples. To evaluate the adhesion of the material between printed layers, compression measurements were performed along the parallel and perpendicular directions to the printing lines.

At a laser density of 70 mW/cm2, Young’s modulus was approximately 6 MPa up to a maximum compression of 20% in the elastic regime for both the parallel and perpendicular measurements. These values were within the range of biological cartilage values. Cytotoxicity tests performed with Vero cells confirmed the cytocompatibility.

We printed a partial tracheal model using optimized printing conditions and proved that the materials and methods developed may be useful for printing of organ models to support surgery or even to produce customized tracheal implants, after further optimization.

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.

Soares, Paula I. P., Joana Romão, Ricardo Matos, Jorge Carvalho Silva, and João Paulo Borges. "Design and engineering of magneto-responsive devices for cancer theranostics: Nano to macro perspective." Progress in Materials Science 116 (2021): 100742. AbstractWebsite

Design, research, and development of new and improved smart multifunctional devices is one of the main topics in the advanced functional materials agenda for the next decade. Smart materials that can be triggered by external stimuli are seen with high potential for innovative treatments and improved drug delivery systems by regulatory agencies like the FDA and EMA. The incorporation of magnetic nanostructures into complex systems produces multifunctional devices that can be spatiotemporally controlled by an external magnetic field. These magneto-responsive devices can be used for a multitude of biomedical applications, from diagnostic to the treatment of tumors, and are actively being developed and tested for cancer theranostics. Herein, we review the development of magneto-responsive devices for cancer theranostics, starting from the most straightforward architecture, single nanoparticles. We give some theoretical concepts about the design and production of such systems while providing a critical review of applications in clinical practice. Naturally, the review evolves to more complex architectures, from one-dimensional to three-dimensional magneto-responsive systems, demonstrating higher complexity and multifunctionality, and consequently, higher interest for clinical practice. The review ends with the main challenges in the design and engineering of magneto-responsive devices for cancer theranostics and future trends in this biomedical field.

Ribeiro, Maximiano P., Ana Espiga, Daniela Silva, Patricia Baptista, Joaquim Henriques, Catarina Ferreira, Jorge Carvalho Silva, João Paulo Borges, Eduardo Pires, Paula Chaves, and Ilídio J. Correia. "Development of a new chitosan hydrogel for wound dressing." Wound repair and regeneration 17 (2009): 817-824. AbstractWebsite

Wound healing is a complex process involving an integrated response by many different cell types and growth factors in order to achieve rapid restoration of skin architecture and function. The present study evaluated the applicability of a chitosan hydrogel (CH) as a wound dressing. Scanning electron microscopy analysis was used to characterize CH morphology. Fibroblast cells isolated from rat skin were used to assess the cytotoxicity of the hydrogel. CH was able to promote cell adhesion and proliferation. Cell viability studies showed that the hydrogel and its degradation by-products are noncytotoxic. The evaluation of the applicability of CH in the treatment of dermal burns in Wistar rats was performed by induction of full-thickness transcutaneous dermal wounds. Wound healing was monitored through macroscopic and histological analysis. From macroscopic analysis, the wound beds of the animals treated with CH were considerably smaller than those of the controls. Histological analysis revealed lack of a reactive or a granulomatous inflammatory reaction in skin lesions with CH and the absence of pathological abnormalities in the organs obtained by necropsy, which supported the local and systemic histocompatibility of the biomaterial. The present results suggest that this biomaterial may aid the re-establishment of skin architecture.

dos Santos, Renato, Ângelo Rocha, Ana Matias, Catarina Duarte, Isabel Sá-Nogueira, Nuno Lourenço, and João Paulo Borges. "Development of antimicrobial Ion Jelly fibers." RSC Advances 3 (2013): 24400-24405. Abstract

We report a method to obtain electrospun fibers based on ionic liquids and gelatin, exhibiting antimicrobial properties.

Raminhos, Joana, João Borges Borges, and Alexandre Velhinho. "Development of polymeric anepectic meshes: auxetic metamaterials with negative thermal expansion." Smart Materials and Structures 28 (2019): 045010. AbstractWebsite

his paper reports the application of additive manufacturing technology to fabricate bi-dimensional lightweight composite meshes capable of demonstrating auxetic properties (negative Poisson's ratio (NPR)) in combination with negative thermal expansion (NTE) behaviour, using as constituent materials polymers that do not exhibit NTE behaviour. To describe the combination of NPR and NTE characteristics, the designation of 'anepectic' is being proposed. Each mesh, obtained from varying either the material combination or the design parameters, was tested on a heated silicone bath to study the effects of the different combinations on the coefficient of thermal expansion (CTE). It was found that all meshes studied demonstrated a successful combination of NPR and NTE behaviours, and it was revealed that there is a possibility to tailor the meshes to activate the NTE behaviour within a chosen range of temperatures. For an extreme case, a Poisson's ratio of −0.056, along with a CTE of −1568 × 10−6 K−1 has been achieved.

Baptista, Ana Catarina, Alexandre Botas, Ana Almeida, Ana Nicolau, Bruno Falcão, Manuel Soares, Joaquim Pratas Leitão, Rodrigo Martins, João Paulo Borges, and Isabel Ferreira. "Down conversion photoluminescence on PVP/Ag-nanoparticles electrospun composite fibers." Optical Materials 39 (2015): 278-281. AbstractWebsite

The influence of Ag nanoparticles (Ag NPs) on the luminescence of electrospun nonwoven mats made of polyvinylpyrrolidone (PVP) has been studied in this work. The PVP fibers incorporating 2.1–4.3 nm size Ag NPs show a significant photoluminescence (PL) band between 580 and 640 nm under 325 nm laser excitation. The down conversion luminescence emission is present even after several hours of laser excitation, which denotes the durability and stability of fibers to consecutive excitations. As so these one-dimensional photonic fibers made using cheap methods is of great importance for organic optoelectronic applications, fluorescent clothing or counterfeiting labels.

Soares, Paula I. P., Sérgio Dias, Carlos Novo, Isabel Ferreira, and João Paulo Borges. "Doxorubicin vs. ladirubicin: methods for improving osteosarcoma treatment." Mini reviews in medicinal chemistry 12 (2012): 1239-1249. AbstractWebsite

Osteosarcoma is the most common primary bone tumor in children and adolescents, with a 5-year disease free survival rate of 70%. Current chemotherapy regimens comprise a group of chemotherapeutic agents in which doxorubicin is included. However, tumor resistance to anthracyclines and cardiotoxicity are limiting factors for its usage. Liposomal formulations of doxorubicin improve its anti-cancer effects but are still insufficient. The research in this area has lead to the production of anthracyclines analogues, such as ladirubicin, the leading compound of alkylcyclines. This new anticancer agent has shown promising results in vivo and in vitro, being effective against osteosarcoma cell lines, including those with a multidrug resistant phenotype. In phase I clinical trials, this molecule caused mild side effects and did not induce significant cardiotoxicity at doses ranging from 1 to 16 mg/m2, resulting in a peak plasma concentration (Cmax) ranging from 0.5 to 1.5 μM. The recommended doses for phase II studies were 12 and 14 mg/m2 in heavily and minimally pretreated/non-pretreated patients, respectively. Phase II clinical trials in ovary, breast, colorectal cancer, NSCLC and malignant melanoma are underway. Given the improved molecular targeting efficacy of these new compounds, ongoing approaches have sought to improve drug delivery systems, to improve treatment efficacy while reducing systemic toxicity. The combination of these two approaches may be a good start for the discovery of new treatment for osteosarcoma.

Soares, Paula I. P., Ana Alves, Laura Pereira, Joana Coutinho, Isabel Ferreira, Carlos Novo, and João Paulo Borges. "Effects of surfactants on the magnetic properties of iron oxide colloids." Journal of Colloid and Interface Science 419 (2014): 46-51. AbstractWebsite

Iron oxide nanoparticles are having been extensively investigated for several biomedical applications such as hyperthermia and magnetic resonance imaging. However, one of the biggest problems of these nanoparticles is their aggregation.
Taking this into account, in this study the influence of three different surfactants (oleic acid, sodium citrate and Triton X-100) each one with various concentrations in the colloidal solutions stability was analyzed by using a rapid and facile method, the variation in the optical absorbance along time.
The synthesized nanoparticles through chemical precipitation showed an average size of 9 nm and a narrow size distribution. X-ray diffraction pattern and Fourier Transform Infrared analysis confirmed the presence of pure magnetite. SQUID measurements showed superparamagnetic properties with a blocking temperature around 155 K. In addition it was observed that neither sodium citrate nor Triton X-100 influences the magnetic properties of the nanoparticles. On the other hand, oleic acid in a concentration of 64 mM decreases the saturation magnetization from 67 to 45 emu/g. Oleic acid exhibits a good performance as stabilizer of the iron oxide nanoparticles in an aqueous solution for 24 h, for concentrations that lead to the formation of the double layer.

Almeida, Pedro L., Sudarshan Kundu, João Paulo Borges, Maria Helena Godinho, and Joao L. Figueirinhas. "Electro-optical light scattering shutter using electrospun cellulose-based nano-and microfibers." Applied Physics Letters 95 (2009): 043501. AbstractWebsite

Electrospun cellulose-based nano and microfibers and a nematic liquid crystal are used to assemble an electro-optical (EO) light-scattering device that shows enhanced characteristics when compared to similar devices. Based on the controlled scattering of light in the composite system, the device can achieve light transmission coefficients tunable from 1% up to around 89%. Simulation of the EO behavior indicates that the roughness of the polymer-liquid crystal interface is crucial for the optical performance of the device.

Baptista, Ana Catarina, Miguel Brito, Ana Marques, and Isabel Ferreira. "Electronic control of drug release from gauze or cellulose acetate fibres for dermal applications." Journal of Materials Chemistry B 9 (2021): 3515-3522. AbstractWebsite

Electronic controlled drug release from fibres was studied using ibuprofen as a model drug, one of the most popular analgesics, to impregnate gauze and cellulose acetate (CA) membranes. Conductivity in the range of 1–10 mS cm−1 was obtained in polypyrrole (Ppy) functionalised gauze and CA fibres, providing voltage-controlled drug release in a system consisting of Ppy/Ibuprofen/Ppy membranes and an Ag electrode. SEM images evidenced the Ppy adhesion to fibres and Micro Raman spectra proved drug incorporation and release. A small wound adhesive built with these membranes retains ibuprofen at 1.5 V and quickly releases it when −0.5 V is applied.

Pimenta, Andreia F. R., Ana Catarina Baptista, Tânia Carvalho, Pedro Brogueira, Nuno Lourenço, Carlos Afonso, Susana Barreiros, Pedro Vidinha, and João Paulo Borges. "Electrospinning of Ion Jelly fibers." Materials Letters 83 (2012): 161-164. AbstractWebsite

Ion Jelly materials combine the chemical versatility and conductivity of an ionic liquid (IL) with the morphological versatility of a biopolymer (gelatin). They exhibit very interesting properties, such as conductivities up to 10− 4 S cm− 1, and high thermostability up to 180 °C, and have been used successfully to design electrochromic windows. In this work we report on the preparation of Ion Jelly fibers through electrospinning in order to obtain high surface area conductive materials. We have used the IL 1-(2-hydroxyethyl)-3-methyl-imidazolium tetrafluoroborate ([C2OHmim]BF4), which exhibits conveniently high ionic conductivity (over 10− 3 S cm− 1) and electrochemical stability (electrochemical window over 6.0 V). The morphology of the obtained fibers was quantified using Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). We found that on average the effect of the IL on fiber diameter differs for lower and higher IL concentrations and that this effect was correlated with the initial conductivity and viscosity of Ion Jelly electrospinning solution. Moreover we also found that conductivities of Ion Jelly fibers are of the same order of magnitude as the conductivities of Ion Jelly dense films (~ 10− 4 S cm− 1). To the best of our knowledge, this is the first report on the incorporation of an IL into gelatin fibers using electrospinning. This opens up new opportunities for the application of gelatin fibers in electrochemical and biomedical devices.

Ferreira, José Luis, Susana Gomes, Célia Henriques, João Paulo Borges, and Jorge Carvalho Silva. "Electrospinning polycaprolactone dissolved in glacial acetic acid: Fiber production, nonwoven characterization, and In Vitro evaluation." Journal of Applied Polymer Science 131 (2014): 41068. AbstractWebsite

The electrospinning of polycaprolactone (PCL) dissolved in glacial acetic acid and the characterization of the resultant nonwoven fiber mats is reported in this work. For comparison purposes, PCL fiber mats were also obtained by electrospinning the polymer dissolved in chloroform. Given the processing parameters chosen, results show that 14 and 17 wt % PCL solutions are not viscous enough and yield beaded fibers, 20 and 23 wt % solutions give rise to high quality fibers and 26 wt % solutions yield mostly irregular and fused fibers. The nonwoven mats are highly porous, retain the high tensile strain of PCL, and the fibers are semicrystalline. Cells adhere and proliferate equally well on all mats, irrespective of the solvent used in their production. In conclusion, mats obtained by electrospinning PCL dissolved in acetic acid are also a good option to consider when producing scaffolds for tissue engineering. Moreover, acetic acid is miscible with polar solvents, which may allow easier blending of PCL with hydrophilic polymers and therefore achieve the production of electrospun nanofibers with improved properties.

Vieira, Tânia, Jorge Carvalho Silva, Botelho A. M. do Rego, João Borges Borges, and Célia Henriques. "Electrospun biodegradable chitosan based-poly(urethane urea) scaffolds for soft tissue engineering." Materials Science and Engineering: C 103 (2019): 109819. AbstractWebsite

The composition and architecture of a scaffold determine its supportive role in tissue regeneration. In this work, we demonstrate the feasibility of obtaining a porous electrospun fibrous structure from biodegradable polyurethanes (Pus) synthesized using polycaprolactone-diol as soft segment and, as chain extenders, chitosan (CS) and/or dimethylol propionic acid. Fourier transform infrared spectroscopy and proton nuclear magnetic resonance confirmed the syntheses. Fibre mats' properties were analysed and compared with those of solvent cast films. Scanning electron microscopy images of the electrospun scaffolds revealed fibres with diameters around 1 μm. From tensile tests, we found that Young's modulus increases with CS content and is higher for films (2.5 MPa to 6.5 MPa) than for the corresponding fibre mats (0.8 MPa to 3.2 MPa). The use of CS as the only chain extender improves recovery ratio and resilience. From X-ray diffraction, a higher crystalline degree was identified in fibre mats than in the corresponding films. Films' wettability was enhanced by the presence of CS as shown by the decrease of water contact angle. X-ray photoelectron spectroscopy revealed that while ester groups are predominant at the films' surface, ester and urethanes are present in similar concentrations at fibres' surface, favouring the interaction with water molecules. Both films and fibres undergo hydrolytic degradation. In vitro evaluation was performed with human dermal fibroblasts. No PU sample revealed cytotoxicity. Cells adhered to fibre mats better than to films and proliferation was observed only for samples of CS-containing PUs. Results suggest that electrospun fibres of CS-based polyurethanes are good candidate scaffolds for soft tissue engineering.

Matos, Ricardo, Catarina Chaparro, Jorge Carvalho Silva, Manuel Valente, João Paulo Borges, and Paula I. P. Soares. "Electrospun composite cellulose acetate/iron oxide nanoparticles non-woven membranes for magnetic hyperthermia applications." Carbohydrate polymers 198 (2018): 9-16. AbstractWebsite

In the present work composite membranes were produced by combining magnetic nanoparticles (NPs) with cellulose acetate (CA) membranes for magnetic hyperthermia applications. The non-woven CA membranes were produced by electrospinning technique, and magnetic NPs were incorporated by adsorption at fibers surface or by addition to the electrospinning solution. Therefore, different designs of composite membranes were obtained. Superparamagnetic NPs synthesized by chemical precipitation were stabilized either with oleic acid (OA) or dimercaptosuccinic acid (DMSA) to obtain stable suspensions at physiological pH. The incorporation of magnetic NP into CA matrix was confirmed by scanning and transmission electron microscopy. The results showed that adsorption of magnetic NPs at fibers’ surface originates composite membranes with higher heating ability than those produced by incorporation of magnetic NPs inside the fibers. However, adsorption of magnetic NPs at fibers’ surface can cause cytotoxicity depending on the NPs concentration. Tensile tests demonstrated a reinforcement effect caused by the incorporation of magnetic NPs in the non-woven membrane.

Baptista, Ana Catarina, Isabel Ferreira, and João Paulo Borges. "Electrospun fibers in composite materials for medical applications." Journal of Composites and Biodegradable Polymers 1 (2013): 56-65. AbstractWebsite

The development of nanoscaled materials has deserved a remarkable interest for biomedical applications. Biological tissues are essentially composite materials with particular mechanical properties that should be carefully considered during the design of innovative biomedical scaffolds. Electrospun membranes are often found in medical applications due to its high specific surface which creates a 3D porous structure that mimics the native extracellular matrix. These electrospun membranes can also be designed to have enhanced mechanical properties, biocompatibility and cellular response making them appealing and inspiring to be used in composites materials.
This paper reviews the new insights in the development of advanced nanostructured composites materials based on electrospun fibers. From tissue engineering to bioelectronics, these composite materials can be found in the most promising research developments for the medical applications.

Franco, Patrícia Q., Carlos João, Jorge Carvalho Silva, and João Paulo Borges. "Electrospun hydroxyapatite fibers from a simple sol–gel system." Materials Letters 67 (2012): 233-236. AbstractWebsite

This work reports the production of hydroxyapatite (HA) sub-micron fibers by combining electrospinning and a non-alkoxide sol–gel system, using cheap precursors. Phosphorus pentoxide (P2O5) and calcium nitrate tetrahydrate (Ca(NO3)2.4H2O) were used as precursors of phosphorus and calcium, respectively. The fibers were electrospun from a mixture of the gel formed from the system Ca(NO3)2.4H2O/P2O5 with polymeric solutions of polyvinylpyrrolidone (PVP) in water and ethanol/water mixtures. The fibers were analyzed for their morphology (Scanning Electron Microscopy, SEM), chemical composition (Fourier Transform Infrared Spectroscopy, FTIR) and structure (X-ray diffraction, XRD). The fibers obtained were composed mainly of type B carbonated HA with traces of β-tricalcium phosphate (β-TCP). SEM analysis revealed that increasing the concentration of water in the solvent system, used in the preparation of electrospinning solutions, led to fibers with smaller diameters and narrower diameter distribution.

Khili, Faouzia, João Borges Borges, Pedro L. Almeida, Rabah Boukherroub, and Amel Dakhlaoui Omrani. "Extraction of Cellulose Nanocrystals with Structure I and II and Their Applications for Reduction of Graphene Oxide and Nanocomposite Elaboration." Waste and Biomass Valorization 10 (2019): 1913-1927. AbstractWebsite

The aim of the present study is to investigate the effect of the hydrolysis process on the properties of nanocrystalline cellulose (NCC) isolated from different precursors and the subsequent use of the extracted NCC for the reduction of graphene oxide (GO). The raw materials (almond and peanut shells) chosen for the isolation of cellulose were selected on the basis of their abundance and their poorly investigation in the production of NCC. Microcrystalline cellulose (MCC) was firstly extracted by alkali and bleaching treatments, then hydrolyzed under different processes to produce NCC polymorphs with structure I (NCC-I) and NCC structure II (NCC-II). The Fourier transform infrared spectroscopy, the X-ray diffraction (XRD) and the 13C NMR studies of the alkali and bleached products confirmed the formation of cellulose type I with high purity and good crystallinity, while scanning electron microscopy (SEM) showed micrometric fibers with lengths reaching 80 µm. Sulfuric acid treatment of these microfibers results in NCC type I or II, depending on the hydrolysis process. SEM of the NCC samples exhibited nanorods with diameter and aspect ratio in the range of 20–40 and 20–25 nm, respectively. Thermogravimetric analysis (TGA) of the MCC and NCC products indicated stable materials with a degradation temperature reaching 240 and 200 °C for MCC and NCC, respectively. The other part of our work concerns the use of the obtained cellulose nanocrystals (type II) for the preparation of reduced graphene oxide composite (NCC/RGO), to demonstrate the reducing properties of the isolated NCCII.

Delgado-Lima, Ana, João Paulo Borges, Isabel Ferreira, and Ana Machado. "Fluorescent and conductive cellulose acetate-based membranes with porphyrins." Materials today Communications 11 (2017): 26-37. AbstractWebsite

The unique properties of electrospun nanofibers combined with functional compounds allow the preparation of novelty materials that can be employed in a wide range of applications. Among a vast number of polymers, Cellulose Acetate (CA) it is considered easy to electrospun and it was employed as the polymeric matrix, where free and iridium-porphyrins were incorporated. Two different solvent systems were employed according to the porphyrin used, and the best dispersion level on both the electrospun solution and the membranes, was achieved with the iridium porphyrin. The nanofibers with this porphyrin also exhibited electrical properties, while the fluorescence was quenched by the presence of specific axial ligands.

Echeverria, Coro, Susete N. Fernandes, Maria Helena Godinho, João Borges Borges, and Paula I. P. Soares. "Functional Stimuli-Responsive Gels: Hydrogels and Microgels." Gels 4 (2018): 54. AbstractWebsite

One strategy that has gained much attention in the last decades is the understanding and further mimicking of structures and behaviours found in nature, as inspiration to develop materials with additional functionalities. This review presents recent advances in stimuli-responsive gels with emphasis on functional hydrogels and microgels. The first part of the review highlights the high impact of stimuli-responsive hydrogels in materials science. From macro to micro scale, the review also collects the most recent studies on the preparation of hybrid polymeric microgels composed of a nanoparticle (able to respond to external stimuli), encapsulated or grown into a stimuli-responsive matrix (microgel). This combination gave rise to interesting multi-responsive functional microgels and paved a new path for the preparation of multi-stimuli “smart” systems. Finally, special attention is focused on a new generation of functional stimuli-responsive polymer hydrogels able to self-shape (shape-memory) and/or self-repair. This last functionality could be considered as the closing loop for smart polymeric gels.