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3D conductive materials such as polymers and hydrogels that interface between biology and electronics are actively being researched for the fabrication of bioelectronic devices. In this work, short-time (5 s) photopolymerizable conductive inks based on poly(3,4-ethylenedioxythiophene) (PEDOT):polystyrene sulfonate (PSS) dispersed in an aqueous matrix formed by a vinyl resin, poly(ethylene glycol) diacrylate (PEGDA) with different molecular weights (M-n = 250, 575, and 700 Da), ethylene glycol (EG), and a photoinitiator have been optimized. These inks can be processed by Digital Light 3D Printing (DLP) leading to flexible and shape-defined conductive hydrogels and dry conductive PEDOTs, whose printability resolution increases with PEGDA molecular weight. Besides, the printed conductive PEDOT-based hydrogels are able to swell in water, exhibiting soft mechanical properties (Young's modulus of similar to 3 MPa) similar to those of skin tissues and good conductivity values (10(-2) S cm(-1)) for biosensing. Finally, the printed conductive hydrogels were tested as bioelectrodes for human electrocardiography (ECG) and electromyography (EMG) recordings, showing a long-term activity, up to 2 weeks, and enhanced detection signals compared to commercial Ag/AgCl medical electrodes for health monitoring. This work was supported by Marie Sklodowska-Curie Research and Innovation Staff Exchanges (RISE) under grant agreement No. 823989 “IONBIKE”.

Eutectogels are an emerging family of soft ionic materials alternative to ionic liquid gels and organogels, offering fresh perspectives for designing functional dynamic platforms in water-free environments. Herein, the first example of mixed ionic and electronic conducting supramolecular eutectogel composites is reported. A fluorescent glutamic acid-derived low-molecular-weight gelator (LMWG) was found to self-assemble into nanofibrillar networks in deep eutectic solvents (DES)/poly(3,4-ethylenedioxythiophene) (PEDOT): chondroitin sulfate dispersions. These dynamic materials displayed excellent injectability and self-healing properties, high ionic conductivity (up to 10−2 S cm−1), good biocompatibility, and fluorescence imaging ability. This set of features turns the mixed conducting supramolecular eutectogels into promising adaptive materials for bioimaging and electrostimulation applications. This work was supported by Marie Sklodowska-Curie Research and Innovation Staff Exchanges (RISE) under the grant agreement No 823989 “IONBIKE”. The financial support received from CONICET and ANPCyT (Argentina) is also gratefully acknowledged. M. C.-G. thanks Emakiker Grant Program of POLYMAT. L. C. T. is grateful to Fundação para a Ciência e a Tecnologia (FCT/MCTES) in Portugal for her research contract under Scientific Employment Stimulus (2020.01555.CEECIND), and Associate Laboratory for Green Chemistry—LAQV, which is also financed by FCT/MCTES (UIDB/50006/2020 and UIDP/50006/2020). D. M. thanks “Ayuda RYC2021-031668-I financiada por MCIN/AEI/10.13039/501100011033 y por la Unión Europea NextGenerationEU/PRTR”. The authors thank the technical and human support provided by SGIker (UPV/EHU/ERDF, EU).

[EN] A new photoinitiator system (PIS) based on riboflavin (Rf), triethanolamine, and multiwalled carbon nanobutes (MWCNTs) is presented for visible-light-induced photopolymerization of acrylic monomers. Using this PIS, photopolymerization of acrylamide and other acrylic monomers was quantitative in seconds. The intervention mechanism of CNTs in the PIS was studied deeply, proposing a surface interaction of MWCNTs with Rf which favors the radical generation and the initiation step. As a result, polyacrylamide/MWCNT hydrogel nanocomposites could be obtained with varying amounts of CNTs showing excellent mechanical, thermal, and electrical properties. The presence of the MWCNTs negatively influences the swelling properties of the hydrogel but significantly improves its mechanical properties (Young modulus values) and electric conductivity. The new PIS was tested for 3D printing in a LCD 3D printer. Due to the fast polymerizations, 3D-printed objects based on the conductive polyacrylamide/CNT nanocomposites could be manufactured in minutes. The authors are thankful for technical and human support provided by IZO-SGI SGIker of UPV/EHU. The authors would like to thank the European Commission for financial support through funding from the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement no. 823989.

Graft copolymers between conducting PEDOT and biodegradable PCL were synthesized and investigated for 3D printing scaffolds for patterning of muscle cells.

Carbon nanotubes (CNTs) have appeared in recent years as innovative components for the development of the next-generation scaffolds to regenerate damaged cardiac tissue. The unique robustness, me-chanical and electronic properties of CNTs, along with their ease to undergo chemical modification, make them promising candidates for the design of engineered cardiac constructs with ad hoc properties. The integration of CNTs with polymeric scaffolds is a promising strategy for cardiac regeneration since, as reviewed in these pages, their conductivity has a boosting effect on cardiomyocytes behavior, including their synchronous contractility when grown on top of the nanomaterial. More recently, the conductive properties of pure CNTs are attracting interest to design innovative systems based on bare CNTs without using other fillers. Additionally, the elongated CNT morphology is a strategic asset for the mimicry of the anisotropic myocardium structure, and research has made great progress over the production of micropatterned scaffolds with nanoscale definition that aim to recapitulate the cardiac tissue. Overall, engineered CNT constructs are revealing their great potential to develop new platforms able to interface, repair, or boost the performance of cardiac tissue. (c) 2021 Elsevier Ltd. All rights reserved.

Carbon nanotubes (CNTs) have become promising advanced materials and a new tool to specifically interact with electroresponsive cells. Likewise, conductive polymers (CP) appear promising electroactive biomaterial for proliferation of cells. Herein, we have investigated CNT blends with two different conductive polymers, polypyrrole/CNT (PPy/CNT) and PEDOT/CNT to evaluate the growth, survival, and beating behavior of neonatal rat ventricular myocytes (NRVM). The combination of CP/CNT not only shows excellent biocompatibility on NRVM, after 2 weeks of culture, but also exerts functional effects on networks of cardiomyocytes. NRVMs cultured on CNT-based substrates exhibited improved cellular function, i.e., homogeneous, non-arrhythmogenic, and more frequent spontaneous beating; particularly PEDOT/CNT substrates, which yielded to higher beating amplitudes, thus suggesting a more mature cardiac phenotype. Furthermore, cells presented enhanced structure: aligned sarcomeres, organized and abundant Connexin 43 (Cx43). Finally, no signs of induced hypertrophy were observed. In conclusion, the combination of CNT with CP produces high viability and promotes cardiac functionality, suggesting great potential to generate scaffolding supports for cardiac tissue engineering.

Nano-bionics have the potential of revolutionizing modern medicine. Among nano-bionic devices, body sensors allow to monitor in real-time the health of patients, to achieve personalized medicine, and even to restore or enhance human functions. The advent of two-dimensional (2D) materials is facilitating the manufacturing of miniaturized and ultrathin bioelectronics, that can be easily integrated in the human body. Their unique electronic properties allow to efficiently transduce physical and chemical stimuli into electric current. Their flexibility and nanometric thickness facilitate the adaption and adhesion to human body. The low opacity permits to obtain transparent devices. The good cellular adhesion and reduced cytotoxicity are advantageous for the integration of the devices in vivo. Herein we review the latest and more significant examples of 2D material-based sensors for health monitoring, describing their architectures, sensing mechanisms, advantages and, as well, the challenges and drawbacks that hampers their translation into commercial clinical devices.

Certainly, the success of polythiophenes is due in the first place to their outstanding electronic properties and superior processability. Nevertheless, there are additional reasons that contribute to arouse the scientific interest around these materials. Among these, the large variety of chemical modifications that is possible to perform on the thiophene ring is a precious aspect. In particular, a turning point was marked by the diffusion of synthetic strategies for the preparation of terthiophenes: the vast richness of approaches today available for the easy customization of these structures allows the finetuning of their chemical, physical, and optical properties. Therefore, terthiophene derivatives have become an extremely versatile class of compounds both for direct application or for the preparation of electronic functional polymers. Moreover, their biocompatibility and ease of functionalization make them appealing for biology and medical research, as it testifies to the blossoming of studies in these fields in which they are involved. It is thus with the willingness to guide the reader through all the possibilities offered by these structures that this review elucidates the synthetic methods and describes the full chemical variety of terthiophenes and their derivatives. In the final part, an in-depth presentation of their numerous bioapplications intends to provide a complete picture of the state of the art. Operational Program Research, Development, and Education Project “MSCAfellow4@MUNI” (No. CZ.02.2.69/0.0/0.0/20_079/0017045) is acknowledged. The European Union is acknowledged for funding this research through Horizon 2020 MSCA-IF-2018 No 838171 (TEXTHIOL).

3D scaffolds appear to be a cost-effective ultimate answer for biomedical applications, facilitating rapid results while providing an environment similar to in vivo tissue. These biomaterials offer large surface areas for cell or biomaterial attachment, proliferation, biosensing and drug delivery applications. Among 3D scaffolds, the ones based on conjugated polymers (CPs) and natural nonconductive polymers arranged in a 3D architecture provide tridimensionality to cellular culture along with a high surface area for cell adherence and proliferation as well electrical conductivity for stimulation or sensing. However, the scaffolds must also obey other characteristics: homogeneous porosity, with pore sizes large enough to allow cell penetration and nutrient flow; elasticity and wettability similar to the tissue of implantation; and a suitable composition to enhance cell-matrix interactions. In this Review, we summarize the fabrication methods, characterization techniques and main applications of conductive 3D scaffolds based on conductive polymers. The main barrier in the development of these platforms has been the fabrication and subsequent maintenance of the third dimension due to challenges in the manipulation of conductive polymers. In the last decades, different approaches to overcome these barriers have been developed for the production of conductive 3D scaffolds, demonstrating a huge potential for biomedical purposes. Finally, we present an overview of the emerging strategies developed to manufacture 3D conductive scaffolds, the techniques used to fully characterize them, and the biomedical fields where they have been applied.

Carbon nanomaterials are at the forefront of the newest technologies of the third millennium, and together with conductive polymers, represent a vast area of indispensable knowledge for developing the devices of tomorrow. This review focusses on the most recent advances in the field of conductive nanotechnology, which combines the properties of carbon nanomaterials with conjugated polymers. Hybrid materials resulting from the embedding of carbon nanotubes, carbon dots and graphene derivatives are taken into consideration and fully explored, with discussion of the most recent literature. An introduction into the three most widely used conductive polymers and a final section about the most recent biological results obtained using carbon nanotube hybrids will complete this overview of these innovative and beyond belief materials. The European Union is acknowledged for funding this research through Horizon 2020 MSCA-IF-2018 No 838171 (TEXTHIOL). IMDEA Nanociencia acknowledges support from the “Severo Ochoa” Programme for Centres of Excellence in R&D (MINECO, Grant SEV- 2016-0686). European Regional Development fund Project “MSCAfellow4 @ MUNI” supported by MEYS CR (No. CZ.02.2.69/0.0/0.0/20_079/0017045) is acknowledged. N.A. has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement no. 753293, acronym NanoBEAT.

Conducting polymers (CPs) have been attracting great attention in the development of (bio)electronic devices. Most of the current devices are rigid two-dimensional systems and possess uncontrollable geometries and architectures that lead to poor mechanical properties presenting ion/electronic diffusion limitations. The goal of the article is to provide an overview about the additive manufacturing (AM) of conducting polymers, which is of paramount importance for the design of future wearable three-dimensional (3D) (bio)electronic devices. Among different 3D printing AM techniques, inkjet, extrusion, electrohydrodynamic, and light-based printing have been mainly used. This review article collects examples of 3D printing of conducting polymers such as poly(3,4-ethylene-dioxythiophene), polypyrrole, and polyaniline. It also shows examples of AM of these polymers combined with other polymers and/or conducting fillers such as carbon nanotubes, graphene, and silver nanowires. Afterward, the foremost applications of CPs processed by 3D printing techniques in the biomedical and energy fields, that is, wearable electronics, sensors, soft robotics for human motion, or health monitoring devices, among others, will be discussed., This work was supported by Marie Sklodowska-Curie Research and Innovation StaffExchanges (RISE) under Grant No. 823989 “IONBIKE”. EU Horizon 2020 FETOPEN-2018−2020 Programme “LION-HEARTED”, Grant No. 828984. N.A. has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie Grant No. 753293, acronym NanoBEAT.

In recent years, 2D materials have been implemented in several applications due to their unique and unprecedented properties. Several examples can be named, from the very first, graphene, to transition-metal dichalcogenides (TMDs, e.g., MoS2), two-dimensional inorganic compounds (MXenes), hexagonal boron nitride (h-BN), or black phosphorus (BP). On the other hand, the accessible and low-cost 3D printers and design software converted the 3D printing methods into affordable fabrication tools worldwide. The implementation of this technique for the preparation of new composites based on 2D materials provides an excellent platform for next-generation technologies. This review focuses on the recent advances of 3D printing of the 2D materials family and its applications; the newly created printed materials demonstrated significant advances in sensors, biomedical, and electrical applications. Financial support from Operational Program Research, Development and Education-Project “MSCAfellow4@MUNI” (CZ.02.2.69/0.0/0.0/20_079/0017045) is acknowledged.

Since their discovery in 1991, carbon nanotubes (CNTs) have been one of the state-of-the-art nanomaterials for application in multiple fields ranging from electronics to tissue engineering. In this chapter, we aim to give an overview on the evolution of CNTs from their discovery and some insights on their peculiar and unique properties. More specifically, CNTs are one of the most promising materials to interface with electrically active tissues, as neuronal and cardiac tissues. Therefore, the last part reviews the last works where the introduction of CNTs into several devices has demonstrated their potential application in neuroscience: microelectrodes for monitoring, stimulation, and recording; sensor devices; drug delivery; imaging; and tissue engineering.

Carbon nanomaterials (CNMs) and conjugated polymers (CPs) are actively investigated in applications such as optics, catalysis, solar cells, and tissue engineering. Generally, CNMs are implemented in devices where the relationship between the active elements and the micro and nanostructure has a crucial role. However, they present some limitations related to solubility, processibility and release or degradability that affect their manufacturing. CPs, such as poly(3,4-ethylenedioxythiophene) (PEDOT) or derivatives can hide this limitation by electrodeposition onto an electrode. In this work we have explored two different CNMs immobilization methods in 2D and 3D structures. First, CNM/CP hybrid 2D films with enhanced electrochemical properties have been developed using bis-malonyl PEDOT and fullerene C60. The resulting 2D films nanoparticulate present novel electrochromic properties. Secondly, 3D porous self-standing scaffolds were prepared, containing carbon nanotubes and PEDOT by using the same bis-EDOT co-monomer, which show porosity and topography dependence on the composition. This article shows the validity of electropolymerization to obtain 2D and 3D materials including different carbon nanomaterials and conductive polymers. This research was funded by the Spanish Ministry of Economy and Competitiveness MINECO (project CTQ2016-76721-R), the University of Trieste, Diputación Foral de Gipuzkoa program Red (101/16), the European Commission (H2020-MSCA-RISE-2016, grant agreement no. 734381, acronym CARBO-IMmap) and ELKARTEK bmG2017 (ref: Elkartek KK-2017/00008, BOPV resolution: 8 Feb 2018). M.P., as the recipient of the AXA Chair, is grateful to the AXA Research Fund for financial support. This work was performed under the Maria de Maeztu Units of Excellence Program from the Spanish State Research Agency Grant no. MDM-2017-0720. N.A. has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement no. 753293, acronym NanoBEAT.

Neuroblastoma-derived SH-SYSY cells have become an excellent model for nervous system regeneration to treat neurodegenerative disorders. Many approaches achieved a mature population of derived neurons in in vitro plates. However, the importance of the third dimension in tissue regeneration has become indispensable to achieve a potential implant to replace the damaged tissue. Therefore, we have prepared porous 3D structures composed uniquely of carbon nanotubes (CNT) and poly(3,4-ethylenedioxythiophene) (PEDOT) that show great potential in the tridimensional differentiation of SH-SYSY cells into mature neurons. The scaffolds have been manufactured through electropolymerization by applying 1.2 V in a three-electrode cell using a template of sucrose/CNT as a working electrode. By this method, PEDOT/CNT 3D scaffolds were obtained with homogeneous porosities and high conductivity. In vitro analyses showed that an excellent biocompatibility of the scaffold and the presence of high amount of beta-tubulin class III and MAP-II target proteins that mainly expresses in neurons, suggesting the differentiation into neuronal cells already after a week of incubation.

Scaffolds that provide an environment similar to the in vivo tissue are essential in tissue engineering. Among them, conducting 3D scaffolds offer large surface areas for cellular attachment, proliferation and additionally for electrical sensing and stimulation. Conducting scaffolds, commonly composed of conjugated polymers (CPs), have shown improved regeneration ability for electrically active cells and tissues, such as muscle, nerves, bones and heart. However, scaffolds are required to also fulfill several other characteristics: porosity to allow cell penetration and nutrient flow; elastic and wettability properties similar to the tissue of interest; and a biocompatible composition to enhance cell–substrate interactions. In this review we summarize the fabrication methods and characterization techniques employed in the case of conducting 3D scaffolds for application in tissue engineering. The main obstacle is generating such structures and maintaining its tridimensionality. In this chapter, we discuss how the scientific community developed or adapt the fabrication techniques to overcome the challenges in the manipulation of conducting polymers. Finally, we present an overview of their application and potential for tissue engineering, also including their feasibility for biomineralization of bone tissue and stem cell differentiation, taking advantage of their conductivity in some cases to regenerate using electrical stimulation.

Tailor-made polymers are needed to fully exploit the possibilities of additive manufacturing, constructing complex, and functional devices in areas such as bioelectronics. In this paper, the synthesis of a conducting and biocompatible graft copolymer which can be 3D printed using direct melting extrusion methods is shown. For this purpose, graft copolymers composed by conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) and a biocompatible polymer polylactide (PLA) are designed. The PEDOT-g-PLA copolymers are synthesized by chemical oxidative polymerization between 3,4-ethylenedioxythiophene and PLA macromonomers. PEDOT-g-PLA copolymers with different compositions are obtained and fully characterized. The rheological characterization indicates that copolymers containing below 20 wt% of PEDOT show the right complex viscosity values suitable for direct ink writing (DIW). The 3D printing tests using the DIW methodology allows printing different parts with different shapes with high resolution (200 µm). The conductive and biocompatible printed patterns of PEDOT-g-PLA show excellent cell growth and maturation of neonatal cardiac myocytes cocultured with fibroblasts.

When graphene is used as SERS substrates, it contributes to the chemical mechanism (CM) of enhancement of Raman signal, owing to which the detection limit is very low (lower than mM content of probe molecules). The CM of enhancement depends largely on the interactions between the substrate and the probe molecules. Therefore, in this work, we have investigated the possibility of increasing the SERS activity of graphene by improving the interaction between the probe molecule and the graphene substrate by establishing exclusively strong covalent bonding between them. Fluorescein (Fl) was selected as a probe molecule because it is one of the most commonly used fluorophore in bioscience. As a graphene substrate, reduced graphene oxide (rGO) platelets were used. In addition, silver nanoparticles (AgNPs) were added onto the hybrids to further increase the enhancement by electromagnetic mechanism. Highly enhanced Raman signal of Fl onto neat rGO was achieved for micromolar concentration of the probe molecules. This was attributed to the covalent bonding between them, which introduced hole doping to rGO, decreasing the Fermi level of rGO and bringing it more closely to the LUMO of Fl. This induces aligning of their energy levels, resulting in higher contribution of the nonresonance effect to the charge transfer mechanism of enhancement, which, in this case, occurred intramolecularly. When AgNPs were added onto the rGO substrate, the expected enhancement performance was not observed. On the one hand, this was attributed to small size (∼20 nm) of AgNPs and lack of aggregates and, on the other, due to the unusually high contribution of CM determined.

Utilizing polymers in cardiac tissue engineering holds promise for restoring function to the heart following myocardial infarction, which is associated with grave morbidity and mortality. To properly mimic native cardiac tissue, materials must not only support cardiac cell growth but also have inherent conductive properties. Here, we present an injectable reverse thermal gel (RTG)-based cardiac cell scaffold system that is both biocompatible and conductive. Following the synthesis of a highly functionalizable, biomimetic RTG backbone, gold nanoparticles (AuNPs) were chemically conjugated to the backbone to enhance the system´s conductivity. The resulting RTG-AuNP hydrogel supported targeted survival of neonatal rat ventricular myocytes (NRVMs) for up to 21 days when cocultured with cardiac fibroblasts, leading to an increase in connexin 43 (Cx43) relative to control cultures (NRVMs cultured on traditional gelatin-coated dishes and RTG hydrogel without AuNPs). This biomimetic and conductive RTG-AuNP hydrogel holds promise for future cardiac tissue engineering applications.

11 Figuras.- Información suplementaria disponible en línea en la web del editor., Three-dimensional scaffolds for cellular organization need to enjoy a series of specific properties. On the one hand, the morphology, shape and porosity are critical parameters and eventually related with the mechanical properties. On the other hand, electrical conductivity is an important asset when dealing with electroactive cells, so it is a desirable property even if the conductivity values are not particularly high. Here, we construct three-dimensional (3D) porous and conductive composites, where C8-D1A astrocytic cells were incubated to study their biocompatibility. The manufactured scaffolds are composed exclusively of carbon nanotubes (CNTs), a most promising material to interface with neuronal tissue, and polypyrrole (PPy), a conjugated polymer demonstrated to reduce gliosis, improve adaptability, and increase charge-transfer efficiency in brain-machine interfaces. We developed a new and easy strategy, based on the vapor phase polymerization (VPP) technique, where the monomer vapor is polymerized inside a sucrose sacrificial template containing CNT and an oxidizing agent. After removing the sucrose template, a 3D porous scaffold was obtained and its physical, chemical, and electrical properties were evaluated. The obtained scaffold showed very low density, high and homogeneous porosity, electrical conductivity, and Young’s Modulus similar to the in vivo tissue. Its high biocompatibility was demonstrated even after 6 days of incubation, thus paving the way for the development of new conductive 3D scaffolds potentially useful in the field of electroactive tissues., M.P. received funding from the Spanish Ministry of Economy and Competitiveness MINECO (project CTQ2016-76721-R), Diputación Foral de Gipuzkoa program Red (101/16), and ELKARTEK bmG2017 (ref: Elkartek KK-2017/00008. BOPV resolution: 8 Feb 2018). N.A. has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie Grant Agreement 753293, acronym NanoBEAT

Organic electronics requires the development of reproducible and highly conductive thin films. The arrangement of poly(3,4-ethylenedioxythiophene) (PEDOT) with fullerene C60 leads to products with the combined properties of both species that are excellent candidates for these applications. However, very little has been studied about the effect of doping PEDOT with C60, and thus there is a lack of information regarding the morphology, electrochemical and electrochromic properties of the resulting films. Herein, simultaneous electrodeposition of poly(3,4-ethylenedioxythiophene) (PEDOT) doped with fullerene C60 was carried out via cyclic voltammetry in the range from 0.0V to +1.5V (vs Ag/AgCl) in a three-compartment cell. ITO coated on PET was used as both working and counter electrodes. The fullerene presence within the films was confirmed with MALDI and TGA (27.5% of fullerene content). The cyclic voltamograms showed that the C60-doped film has a higher oxidation potential, what was attributed to the electron affinity of the fullerene cage. Furthermore, the spectroelectrochemical and electrochromic analyses showed that the PEDOT/C60 films present a dark violet coloration in the reduced state, which differs from the usual dark blue of the PEDOT polymer. Finally, the morphology was analyzed using AFM and SEM, and pillar structure of broccoli-like particles was observed for both films. However, the fullerene doping generated smaller polymer-based particles, thus forming a denser structure with higher surface area, suggesting the use of the cages as nucleation points for the polymerization

C66 is one of the smallest fullerenes that is able to encapsulate more than one metal atom, as in Sc2@C66, as well as to get chlorinated at a low level, C66Cl10 or C66Cl6. We show here, with the help of computations at density functional theory level, that these two means of obtaining derivatives of non-isolated pentagon rule fullerenes are dictated by different factors. Chlorination takes place at temperatures lower than 2000 K, once the neutral fullerenes are formed. Encapsulation is, however, mainly governed by the charge transfer, although the Sc···Sc distance is also playing a role in the stability of Sc2@C66.

The design, synthesis, and electronic properties of a new series of D-π-A conjugates consisting of free base (H2P) and zinc porphyrins (ZnP) as electron donors and a fullerene (C60) as electron acceptor, in which the two electroactive entities are covalently linked through pyridine-vinylene spacers of different lengths, are described. Electronic interactions in the ground state were characterized by electrochemical and absorption measurements, which were further supported with theoretical calculations. Most importantly, charge-transfer bands were observed in the absorption spectra, indicating a strong push-pull behavior. In the excited states, electronic interactions were detected by selective photoexcitation under steady-state conditions, by time-resolved fluorescence investigations, and by pump probe experiments on the femto−, pico−, and nanosecond time scales. Porphyrin fluorescence is quenched for the different D-π-A conjugates, from which we conclude that the deactivation mechanisms of the excited singlet states are based on photoinduced energy- and/or electron transfer processes between H2P/ZnP and C60, mediated through the molecular spacers. The fluorescence intensity decreases and the fluorescence lifetimes shorten as the spacer length decreases and as the spacer substitution changes. With the help of transient absorption spectroscopy, the formation of charge-separated states involving oxidized H2P/ZnP and reduced C60 was confirmed. Lifetimes of the corresponding charge-separated states, which ranged from ~ 400 picoseconds to 165 nanoseconds, depend on the spacer length, the spacer substitution, and the solvent polarity. Interestingly, D-π-A conjugates containing the longest linkers did not necessarily exhibit the longest charge-separated state lifetimes. The distances between the electron donors and the acceptors were calculated by conformational analysis. The longest charge-separated state lifetime corresponded to the D-π-A conjugate with the longest electron donor-acceptor distance. Likewise, EPR measurements in frozen media revealed charge separated states in all the D-π-A conjugates investigated. A sharp peak with g values ~ 2.000 was assigned to reduced C60, while a broader, less intense signal (g ~ 2.003) was assigned to oxidized H2P/ZnP. On-off switching of the formation and decay of the charge-separated states was detected by EPR at 77 K by repeatedly turning the irradiation source on and off.

Bingel-Hirsch reactions on fullerenes take place under kinetic control. We here predict, by means of DFT methodology, the products of the Bingel-Hirsch addition on non-isolated-pentagon-rule (non-IPR) metallofullerenes Gd3N@C2n (2n = 82, 84), as modeled by closed-shell Y3N@C2n systems. Adducts on [6,6] B-type bonds placed near the pentalene unit are predicted for the two cages, as found for other non-IPR endohedral fullerenes such as Sc3N@C68.

Endohedral metallofullerenes (EMFs) containing lanthanides are thoroughly analyzed using density functional theory. Our methodology, which uses planes waves as basis functions and pseudopotentials and takes into account the on-site Coulomb repulsion via the Hubbard-like U parameter, is able to reproduce the electronic structure and the main geometrical parameters for this family of compounds that presents unpaired f electrons. In addition, the relative abundances of lanthanide EMFs observed in chromatograms as well as the preference of a nitride cluster for a given fullerene are properly predicted. Cluster–cage interactions are optimal when the cluster fits perfectly within the available hollow space of the carbon cage. Except for cerium nitride fullerenes, f electrons do not play a significant role in the electrochemical properties of lanthanide EMFs. If one is only interested in a qualitative prediction of the structure, reactivity, and electronic properties, then calculations that do not explicitly con...

An extensive theoretical study of the Bingel-Hirsch addition of bromomalonate on scandium nitride endohedral fullerenes has been carried out. The prototypical and highly symmetrical Sc3N@I(h)-C80, with a structure that satisfies the isolated pentagon rule (IPR), and the non-IPR Sc3N@D3(6140)-C68 fullerene show analogous reaction paths despite the distinct topology of the carbon networks and different rotation freedom of the internal nitride cluster. For the two metallofullerenes, our results predict that the reaction takes place under kinetic control yielding open-cage fulleroids on [6,6] bonds, which is in good agreement with experimental data. The theoretical studies also show that predicting the reactivity of endohedral metallofullerenes is not straightforward and often an accurate analysis of the potential energy surface is required.

The utilization of graphene-based nanomaterials combined with magnetic nanoparticles offers key benefits in the modern biomedicine. In this minireview, we focus on the most recent advances in hybrids of magnetic graphene derivatives for biomedical applications. We initially analyze the several methodologies employed for the preparation of graphene-based composites with magnetic nanoparticles, more specifically the kind of linkage between the two components. In the last section, we focus on the biomedical applications where these magnetic-graphene hybrids are essential and pay special attention on how the addition of graphene improves the resulting devices in magnetic resonance imaging, controlled drug delivery, magnetic photothermal therapy and cellular separation and isolation. Finally, we highlight the use of these magnetic hybrids as multifunctional material that will lead to a next generation of theranostics.

Using a purification method introduced earlier based on redox properties, it is possible to isolate Sc3N@Ih-C80 and Sc3N@D3h-C78 and a mixture of Sc3N@D5h-C80 and Sc3N@D3-C68.

The behaviour of double stranded DNA molecules (dsDNA) attached to single walled carbon nanotubes (SWCNTs) was investigated by molecular dynamics simulations. We observe that disruption of short dsDNA helices is accelerated by the presence of SWCNT due to the establishment of π-stacking interactions between the nucleobases and the sidewall of the nanotubes. These results are in good agreement with experimental evidences and confirm the mechanism of assembly between a single stranded DNA molecule and a SWCNT. Longer DNA molecules maintain the structure of a double helix although with the hydrogen-bonding network slightly altered on the relatively short time scale.

Fullerenes tend to follow the isolated pentagon rule, which requires that each of the 12 pentagons is surrounded only by hexagons. Over the past decade many violations to this rule were reported for endohedral fullerenes. Based on the ionic model M(3)N(6+)@C(2n)(6-) and the orbital energies of the isolated cages, in 2005 we formulated a molecular orbital rule to identify the most suitable hosting cages in endohedral metallofullerenes. Now, we give physical support to the orbital rule, and we propose the maximum pentagon separation rule, which can be applied to either isolated pentagon rule cages or to non-isolated pentagon rule cages with the same number of adjacent pentagon pairs. The maximum pentagon separation rule can be formulated as 'The electron transfer from the internal cluster to the fullerene host preferentially adds electrons to the pentagons; therefore, the most suitable carbon cages are those with the largest separations among the 12 pentagons'.

The on–off switch of charge separated states in a new series of pyridine-vinylene linked porphyrin–C60 conjugates was detected by EPR at 77 K., The design, synthesis, and electronic properties of a new series of D–π–A conjugates consisting of free base (H2P) and zinc porphyrins (ZnP) as electron donors and a fullerene (C60) as electron acceptor, in which the two electroactive entities are covalently linked through pyridine-vinylene spacers of different lengths, are described. Electronic interactions in the ground state were characterized by electrochemical and absorption measurements, which were further supported with theoretical calculations. Most importantly, charge-transfer bands were observed in the absorption spectra, indicating a strong push–pull behavior. In the excited states, electronic interactions were detected by selective photoexcitation under steady-state conditions, by time-resolved fluorescence investigations, and by pump probe experiments on the femto-, pico-, and nanosecond time scales. Porphyrin fluorescence is quenched for the different D–π–A conjugates, from which we conclude that the deactivation mechanisms of the excited singlet states are based on photoinduced energy- and/or electron transfer processes between H2P/ZnP and C60, mediated through the molecular spacers. The fluorescence intensity decreases and the fluorescence lifetimes shorten as the spacer length decreases and as the spacer substitution changes. With the help of transient absorption spectroscopy, the formation of charge-separated states involving oxidized H2P/ZnP and reduced C60 was confirmed. Lifetimes of the corresponding charge-separated states, which ranged from ∼400 picoseconds to 165 nanoseconds, depend on the spacer length, the spacer substitution, and the solvent polarity. Interestingly, D–π–A conjugates containing the longest linkers did not necessarily exhibit the longest charge-separated state lifetimes. The distances between the electron donors and the acceptors were calculated by molecular modelling. The longest charge-separated state lifetime corresponded to the D–π–A conjugate with the longest electron donor–acceptor distance. Likewise, EPR measurements in frozen media revealed charge separated states in all the D–π–A conjugates investigated. A sharp peak with g values ∼2.000 was assigned to reduced C60, while a broader, less intense signal (g ∼ 2.003) was assigned to oxidized H2P/ZnP. On–off switching of the formation and decay of the charge-separated states was detected by EPR at 77 K by repeatedly turning the irradiation source on and off.

From a comparison with the already isolated and characterized Sc4(μ3-O)3@C80 metallofullerene, we propose here that an even larger 8-atom cubane oxide M4(μ3-O)4 could also be encapsulated inside other middle-size fullerenes that would formally accept four electrons. Several possibilities are suggested for M = Sc and Lu.

Similar yet different: A one-step regio- and diastereoselective synthesis of three new bis(pyrrolidine)[60]fullerenes, one cis-1 and two unprecedented cis-2 diastereoisomers, is reported. The compounds are easily purified using simple chromatographic techniques, and were fully characterized by spectroscopic techniques and X-ray crystallography. A mechanism for the isomeric conversion observed is proposed.

10.1016/j.crci.2011.09.004 The electronic structure of endohedral metallofullerenes is rationalized by connecting the apparently independent orbital and topological rules that explain the stability of this family of fullerenes. The separation of the 12 pentagons of the fullerene, which is maximized in order to minimize the Coulomb repulsion, is found to be correlated with the orbital energies of the cage that accepts the electron transfer from the internal cluster. An explanation for the absence of non-IPR cages in large-size EMFs is also provided.

The Bingel-Hirsch reactions on non-isolated pentagon rule (non-IPR) Gd(3)N@C(2n) (2n = 82, 84) are studied. Computational results show that the two metallofullerenes display similar reactivity according to their related topologies. Long C-C bonds with large pyramidalization angles lead to the most stable adducts, the [5,6] bonds in the adjacent pentagon pair being especially favored. The lesser regioselectivity observed for Gd(3)N@C(82) is probably due to the activation of some C-C bonds by means of the metal cluster.

8 figures.-- Supporting information available on the editor's web page.-- This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Biomaterials Science & Engineering, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://dx.doi.org/10.1021/acsbiomaterials.9b01316, Three-dimensional (3D) scaffolds with tailored stiffness, porosity, and conductive properties are particularly important in tissue engineering for electroactive cell attachment, proliferation, and vascularization. Carbon nanotubes (CNTs) and poly(3,4-ethylenedioxythiophene) (PEDOT) have been extensively used separately as neural interfaces showing excellent results. Herein, we combine both the materials and manufacture 3D structures composed exclusively of PEDOT and CNTs using a methodology based on vapor phase polymerization of PEDOT onto a CNT/sucrose template. Such a strategy presents versatility to produce porous scaffolds, after leaching out the sucrose grains, with different ratios of polymer/CNTs, and controllable and tunable electrical and mechanical properties. The resulting 3D structures show Young’s modulus typical of soft materials (20–50 kPa), as well as high electrical conductivity, which may play an important role in electroactive cell growth. The conductive PEDOT/CNT porous scaffolds present high biocompatibility after 3 and 6 days of C8-D1A astrocyte incubation., The Spanish Ministry of Economy and Competitiveness MINECO (project CTQ2016-76721-R), the University of Trieste, Diputación Foral de Gipuzkoa program Red (101/16), and the European Commission (H2020-MSCA-RISE-2016, grant agreement no. 734381, acronym CARBO-IMmap) and ELKARTEK bmG2017 (Ref: Elkartek KK-2017/00008, BOPV resolution: 8 Feb 2018) are gratefully acknowledged for financial support. MP, as the recipient of the AXA Chair, is grateful to the AXA Research Fund for financial support. This work was performed under the Maria de Maeztu Units of Excellence Program from the Spanish State Research Agency—grant no. MDM-2017-0720. NA has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 753293, acronym NanoBEAT.