Publications

The transition from insulator to electro-responsive has been successfully achieved by earlier studies for some inorganic materials by applying external stimuli that modify their 3D and/or electronic structures. In the case of insulating polymers, this transition is frequently accomplished by mixing them with other electroactive materials, even though a few physical treatments that induce suitable chemical modifications have also been reported. In this work, a smart approach based on the application of an electro-thermal reorientation process followed by a charged gas activation treatment has been developed for transforming insulating 3D printed polymers into electro-responsive materials. First, the developed procedure has been exhaustively investigated for 3D printed poly(lactic acid) (PLA) and subsequently has been extended to 3D printed polypropylene (PP) and poly(ethylene terephthalate glycol) (PETG) specimens. FTIR and Raman spectroscopies, X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and water contact angle measurements confirmed that, while the electro-thermal reorientation mainly promotes the crystallinity of the samples, the charged gas activation oxidizes the C-O bonds at the surface and consequently modifies the surface morphology and wettability. Furthermore, cyclic voltammetry assays demonstrated that treated PLA, PP, and PETG are electro-responsive, even though the electrochemical activity was much higher for oxygen-containing polymers (PLA and PETG) than for the oxygen-free one (PP). Finally, as a proof of concept, treated 3D printed PLA specimens have been used as electrochemical sensors to detect dopamine (DA), an important neurotransmitter, in a concentration interval ranging from 50 to 1000 mu M. The peak associated with the oxidation from DA to dopaminoquinone and the linearity of the calibration plot, which was constructed using the anodic peak current, proved that treated PLA is not only electro-responsive but also able to electrocatalyze the oxidation of DA.

JTD Keywords: 3d printin, Blends, Dopamine, Electrochemical detection, Electrochemical sensors, Electroresponsive polymers, Films, Hydrogels, Pl, Plasma treatment, Release, Thermoelectric treatment, Thermoplastic polymers

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.

JTD Keywords: 3d printers, Additive manufacturing, Amines, Batch manufacturing, Biomedical applications, Chronoamperometry, Conducting polymer, Conducting polymers, Conductive filaments, Conservation, Cyclic voltammetry, Differential pulse voltammetry, Electroactive material, Electrochemical biosensor, Electrochemical devices, Electrochemical sensors, Electrodes, Electron emission, Flexible electrode, High reproducibility, Medical applications, Neurophysiology, Poly-3 ,4-ethylenedioxythiophene, Polyesters, Polylactic aci, Sodium hydroxide, Tensile strength, Thermoplastic polymer