Multi sensor compatible 3D-printed electrochemical cell for voltammetric drug screening

Abstract

3D printing is a hot topic in electroanalytical chemistry, allowing the construction of custom cells and sensors at affordable prices. In this work, we describe a novel small and practical 3D-printed electrochemical cell. The cell's body, manufactured in ABS on a 3D printer, is composed by three parts easily screwed: solution vessel, stick and cover with two embedded 3D-pen-printed carbon black-polylactic acid (CB-PLA) electrodes (counter and pseudo-reference). The cell is compatible with any planar working electrode, in which boron-doped diamond, graphite sheet (GS) and 3D-printed CB-PLA were shown as examples. A new alternative protocol to quickly produce 3D-printed sensors using a 3D pen and other low-cost apparatus is also proposed. The voltammetric performance of each evaluated sensor was carried out in the presence of redox probe ferricyanide and paracetamol as model analyte, and the surfaces were characterized by electrochemical impedance spectroscopy and scanning electrochemical microscopy. To present an analytical application of the 3D-printed cell, low-cost flexible sensors (GS and CB-PLA) were used as integrated platforms for sampling and detection of solid drugs. As a proof-of-concept, traces of drugs with a historic of counterfeit or adulteration (sildenafil citrate, tadalafil, losartan and 17α-ethinylestradiol) were abrasively sampled over the sensor and assembled on 3D-printed cell to perform a fast voltammetric scan in the presence of only 500 μL of electrolyte. This protocol is attractive for pharmaceutical and forensic sciences as a simple preliminary screening method which could identify the presence or absence of the suspicious drug as well as impurities or adulterants. The 3D-printed cell was also used for the determination of 17α-ethinylestradiol in a contraceptive pill to demonstrate a quantitative analysis. The cell is quickly printed (90 min), cheap (US$ 0.30) and requires low electrolyte volumes (0.5–3.0 mL), being suitable to be used in several other electroanalyses, especially for on-site applications.