Integrated electrochemical sensors in which plasma‐treated poly(lactic acid) (PLA) single material acts as both selective coating layer and electrochemical transductor (electrode) are prepared. Thus, ...three‐dimensional‐printed PLA specimens are transformed into electroresponsive material by applying a low‐pressure gas plasma treatment with three different gases: N2, O2, and air (79% N2 + 21% O2). Although all treated samples are able to electrochemically detect dopamine, the one derived from the treatment of low‐pressure O2 plasma exhibits the best performance as a sensor. Finally, cell adhesion assays demonstrate that the cell viability is higher for plasma‐treated PLA modified than for pristine PLA, making the former a promising, versatile, and powerful electroresponsive platform for diverse applications in biomedicine.
Electrochemical sensors in which plasma‐treated poly(lactic acid) (PLA) acts as both selective coating layer and electrode have been prepared. For this purpose, low‐pressure O2, N2, or air plasma has been applied to PLA specimens that have been previously shaped using three‐dimensional printing. The performance of the prepared sensors, which exhibit higher cell viability than pristine PLA, has been tested by detecting dopamine. Sensors obtained using low‐pressure O2 plasma display a lower detection limit and higher linearity than those prepared by applying low‐pressure N2 and air plasmas.
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•Electrochemical sensors were prepared by 3D printing using electrically inert PLA.•Inert PLA was transformed into electro-responsive applying a plasma treatment.•The surface ...modification of PLA was optimal using a 0.8 mbar O2 plasma treatment.•Modified PLA was able to electrocatalyze dopamine oxidation.•Modified PLA detected simultaneously dopamine and glucose.
Electrochemical sensors for real-time detection of several bioanalytes have been prepared by additive manufacturing, shaping non-conductive poly(lactic acid) (PLA) filaments, and applying a physical treatment to create excited species. The latter process, which consists of the application of power discharge of 100 W during 2 min in a chamber at a low pressure of O2, converts electrochemically inert PLA into an electrochemically responsive material. The electric discharge caused the oxidation of the PLA surface as evidenced by the increment in the quantity of oxygenated species detected by FTIR spectroscopy and X-ray photoelectron spectroscopy (XPS). Indeed, changes in the surface chemical composition became more pronounced with increasing O2 pressure. After demonstrating the performance of the chemically modified material as individual dopamine and glucose sensors, multiplexed detection has been achieved by measuring simultaneously the two voltammetric signals. This has been performed by collecting the signals in two different regions, a naked chemically modified PLA for dopamine detection and a chemically modified PLA region functionalized with Glucose Oxidase. These outcomes led to define a new paradigm for manufacturing electrodes for electrochemical sensors based on 3D printing without using conducting materials at any stage of the process.
Electrochemically responsive hydrogel networks have been obtained using printable inks made of a biopolymer, alginate (Alg), and an inorganic 2D material, MXene (titanium carbide, Ti3C2Tx) ...nanosheets. While MXene offers an electrically conductive pathway for electron transfer and Alg provides an interconnected framework for ion diffusion, the printed nanocomposite results, after gelation, in an extended active interface for redox reactions, being an ideal framework to design and construct flexible devices for biomedical applications. In this work, after characterization, we demonstrate that hydrogels obtained by cross-linking printed Alg/MXene inks exhibit great potential for bioelectronics. More specifically, we prove that flexible Alg/MXene hydrogels act as self-supported electroactive electrodes for the electrochemical detection of bioanalytes, such as dopamine, with a performance similar to that achieved using more sophisticated electrodes, as for example those containing conducting polymers and electrocatalytic gold nanoparticles. In addition, Alg/MXene hydrogels have been successfully used to regulate the release of a previously loaded broad spectrum antibiotic (chloramphenicol) by electrical stimulation.
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•Printable inks made of alginate (Alg) and MXene nanosheets have been formulated.•Electrochemically responsive hydrogels have been obtained using printable inks.•Hydrogels behave as active redox interfaces useful for biomedical applications.•Hydrogels act as self-supported electrodes for the electro-detection of dopamine.•The potential of hydrogels to release drugs under electrostimulation is proved.
The development of smart biomedical devices as efficient tools in early diagnosis and therapy monitoring has recently witnessed unprecedented growth, becoming an emerging field in biomedical ...engineering. Sponges for endoluminal vacuum therapy, which are intended for transmitting negative pressure as trigger for tissue regeneration and for draining infections in anastomotic leakages, are massively used implants with very complex geometry and high risk of infection. In this work, commercial polyurethane (PU) sponges have been converted into smart biomedical devices by incorporating an electrochemical sensor to monitor the growth of bacteria. Such innovative approach, which allows to track the tissue healing process avoiding further infection development, has been performed applying a three-step process: 1) activation of PU using low pressure oxygen plasma; 2) incorporation of conducting polymer (CP) nanoparticles (NPs) at the surface of the activated PU by chemical oxidative polymerization; and 3) formation of a homogeneous electroactive coating using the CP NPs obtained in 2), as growth nuclei in an electrochemical polymerization. The functionalized PU sponge is able to monitor the bacteria growth in the surrounding media by detecting the concentration of nicotinamide adenine dinucleotide (NADH) from respiration reactions in the cytosol (i.e. bacteria do not have mitochondria). Conversely, respiration in normal eukaryotic cells takes place in the mitochondria, whose double membrane is not permeable to NADH. The sensing performance of the CP-coated PU sponges (limit of detection: 0.06 mM; sensitivity: 1.21 mA/cm2) has been determined in the lab using NADH solutions, while a proof of concept have been conducted using Escherichia coli bacteria cultures.
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•Surgical sutures coated with conducting polymer detect bacterial infections.•A hydrogel layer prevents the detachment of the sensor upon handling the suture.•PDA-PAM hydrogel is ...particularly suitable due to its porosity and adhesive properties.•The functionality of the protected sutures has been proved using ex-vivo assays.•Electrostimuli inhibit the local growth of bacteria in functionalized sutures.
Surgical sutures are long-established medical devices that play an important role closing and healing damaged tissues and organs postoperatively. However, current commercial sutures are not able to detect infections at the wound site, which are quite frequent after surgery. In this work, we present mechanically stable smart sutures for the real-time monitoring of bacterial growth and biofilm formation. For this purpose, a conducting polymer named poly(3,4-ethylenedioxythiophene) (PEDOT), which is able to detect bacteria metabolites, was implemented as a coating onto commercial biostable sutures. A protecting hydrogel layer with adhesive properties, which was made of polydopamine-polyacrylamide (PDA-PAM), was used to prevent the detachment of the sensing coating of PEDOT upon looping and knotting the suture. The protective hydrogel preserved not only the knot mechanical properties of the suture but also the electrochemical response of the PEDOT-coating and, therefore, its ability to detect NADH from bacteria respiration. Ex-vivo assays using sutured swine intestine samples demonstrated that the suture with the PDA-PAM hydrogel layer detects the growth of bacteria in real tissues. As a proof of concept, sutures coated with PEDOT and protected with PDA-PAM were used to inhibit the local growth of bacteria in sutured intestines by applying controlled electrostimuli. Results evidenced that smart electro-responsive sutures can be used as multi-task devices focused on fighting bacterial infections, meaning not only monitoring but also hampering bacteria growth.
In the present study, a composite made of conducting polymer, poly(3,4-ethylenedioxythiophene) (PEDOT), and a biodegradable hydrogel of poly(aspartic acid) (PASP) were electrochemically ...interpenetrated with poly(hydroxymethyl-3,4-ethylenedioxythiophene) (PHMeDOT) to prepare a new interpenetrated polymer network (IPN). Different cross-linker and PEDOT MPs contents, as well as different electropolymerization times, were studied to optimize the structural and electrochemical properties. The properties of the new material, being electrically conductive, biocompatible, bioactive, and biodegradable, make it suitable for possible uses in biomedical applications.
Polypropylene (PP), thermoplastic polyurethane (TPU), polyethylene terephthalate glycol (PETG) and polylactic acid (PLA) 3D printed specimens, which are intrinsically non-electroresponsive materials, ...have been converted into electroresponsive electrodes applying a low-pressure oxygen plasma treatment. After complete chemical, morphological and electrochemical characterization, plasma treated samples have been applied as integrated electrochemical sensors for detecting dopamine and serotonin by cyclic voltammetry and chronoamperometry. Results show differences in the sensing behavior, which have been explained on the basis of the chemical structure of the pristine materials. While plasma treated PLA exhibits the highest performance as electrochemical sensor in terms of sensitivity (lowest limits of detection and quantification) and selectivity (against uric acid and ascorbic acid as interfering substances), plasma treated PP displays the poorest behavior due to its low polarity compared to PLA 3D-printed electrodes. Instead, plasma treated TPU and PETG shows a very good response, much closer to PLA, as sensitive electrodes towards neurotransmitter molecules (dopamine and serotonin). Overall, results open a new door for the fabrication of electrochemical conductive sensors using intrinsically insulating materials, without the need of chemical functionalization processes.
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•Inert 3D printed plastics were transformed in electrochemical sensors.•Electro-responsive plastics were obtained applying a plasma treatment.•The electrochemical properties of the treated plastics depend on the C:O ratio.•The sensitivity and selectivity of treated plastics to detect was demonstrated.•Polylactic acid showed the best performance as electrochemical sensor.
Isotactic polypropylene (i-PP) nonabsorbable surgical meshes are modified by incorporating a conducting polymer (CP) layer to detect the adhesion and growth of bacteria by sensing the oxidation of ...nicotinamide adenine dinucleotide (NADH), a metabolite produced by the respiration reactions of such microorganisms, to NAD+. A three-step process is used for such incorporation: (1) treat pristine meshes with low-pressure O
plasma; (2) functionalize the surface with CP nanoparticles; and (3) coat with a homogeneous layer of electropolymerized CP using the nanoparticles introduced in (2) as polymerization nuclei. The modified meshes are stable and easy to handle and also show good electrochemical response. The detection by cyclic voltammetry of NADH within the interval of concentrations reported for bacterial cultures is demonstrated for the two modified meshes. Furthermore,
and both biofilm-positive (B+) and biofilm-negative (B-)
cultures are used to prove real-time monitoring of NADH coming from aerobic respiration reactions. The proposed strategy, which offers a simple and innovative process for incorporating a sensor for the electrochemical detection of bacteria metabolism to currently existing surgical meshes, holds considerable promise for the future development of a new generation of smart biomedical devices to fight against post-operative bacterial infections.
Flexible electrochemical sensors based on electroactive materials have emerged as powerful analytical tools for biomedical applications requiring bioanalytes detection. Within this context, 3D ...printing is a remarkable technology for developing electrochemical devices, due to no design constraints, waste minimization, and batch manufacturing with high reproducibility. However, the fabrication of 3D printed electrodes is still limited by the in‐house fabrication of conductive filaments, which requires the mixture of the electroactive material with melted of thermoplastic polymer (e.g., polylactic acid, PLA). Herein, a simple approach is presented for preparing electrochemical dopamine (DA) biosensors. Specifically, the surface of 3D‐printed PLA specimens, which exhibit an elastic modulus and a tensile strength of 3.7 ± 0.3 GPa and 47 ± 1 MPa, respectively, is activated applying a 0.5 m NaOH solution for 30 min and, subsequently, poly(3,4‐ethylenedioxythiophene) is polymerized in situ using aqueous solvent. The detection of DA with the produced sensors has been demonstrated by cyclic voltammetry, differential pulse voltammetry, and chronoamperometry. In summary, the obtained results reflect that low‐cost electrochemical sensors, which are widely used in medicine and biotechnology, can be rapidly fabricated using the proposed approach that, although based on additive manufacturing, does not require the preparation of conductive filaments.
A simple approach is proposed for the fabrication of flexible electrochemical biosensors using 3D‐printing technology. This is consists on 3D‐printed polylactic acid electrodes, which are subsequently treated with NaOH and coated with a conducting polymer layer. Electrochemical measures for the selective detection of dopamine demonstrates that this approach is a reliable alternative to in‐house fabrication of composite conductive filaments.
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