Biodegradable and Flexible Thermoplastic Composite Graphite Electrodes: A Promising Platform for Inexpensive and Sensitive Electrochemical Detection of Creatine Kinase at the Point-of-Care

Abstract

Acute myocardial infarction (AMI) is the main cause of death worldwide, and the time of diagnosis is decisive for the effectiveness of the treatment of patients with AMI. Creatine kinase-myocardial band (CK-MB) has a predominance and high affinity with myocardial tissue, making it considered one of the main biomarkers for the diagnosis of AMI. In this work, we report a novel biodegradable composite material based on a polymer blend of Poly­(3-hydroxybutyrate-co-3-hydroxyvalerate) and Poly­(butylene adipate-co-terephthalate) (PHBV:Ecoflex) and graphite microparticles for sensitive and selective electrochemical detection of CK-MB. The morphological and physicochemical characterizations of the thermoplastic composite material revealed a homogeneous and synergistic distribution of the graphite microparticles through the blend structure, providing low defects and high electrical conductivity with high electron transfer kinetics (k 0 = 3.54 × 10–3 cm s–1) features with adequate flexibility for point-of-care applications. The portable and disposable devices were applied to detect CK-MB using the electrochemical impedance spectroscopy (EIS) technique in a relevant clinical concentration ranging from 5.0 ng mL–1 to 100.0 ng mL–1 and presented a limit of detection of 0.26 ng mL–1 CK-MB. The selectivity of the sensor was confirmed by testing the potential interference of major biomolecules found in biofluids and other relevant macromolecules. The accuracy and robustness were assessed by addition and recovery protocol in urine and saliva samples without sample pretreatment and demonstrated the potential of our method for rapid and decentralized tests of AMI. In addition, the study of the thermal, biological, and photodegradation of the devices after being used was also carried out, aiming at the disposal of the material more sustainably.

Electrochemical Paper-Based Nanobiosensor for Rapid and Sensitive Detection of Monkeypox Virus

“…Under optimized engraving conditions and cathodically treated, the unmodified LSG electrode (black lines) exhibited an R CT and I pa of 25.5 Ω and 109.6 μA, respectively. After the electrodeposition with the AuNS onto the LSG electrode (red line), the electrode surface exhibited a high peak current and lower electrical resistance ( I pa = 202.9 μA and R CT = 11.8 Ω) due to the enhancement of the electroactive area and the AuNS acts as a nanospacer and metallic conductor. − However, at the LSG/AuNS/Ab-MPX electrode (green line), the I pa value decreased (174.3 μA) and the R CT increased (120.7 Ω) due to the partial block of the electrode’s surface promoted by MPXV antibody immobilization, hindering the access of [Fe­(CN 6 )] 3–/4– to the electrode surface, which enables the decrease of electrical current and increase of the electrical resistance . Subsequently, the addition of 1.0% BSA (m/v) onto the modified electrode surface decreases the I pa to 128.5 μA and increases the R CT to 216.9 Ω, which is the result of the hindering access of the redox probe to the electrode surface.…”

“…To circumvent these problems, electrochemical biosensors are an interesting approach due to the usual short testing time, instrumental portability, and device miniaturization, which reduce the sample volume needed to run the test and eliminate or minimize sample pretreatment steps, enabling POC applications. − For optimal applications at POC, electrochemical devices should be accessible and reproducible to be made disposable, alleviating the need for trained operators. To achieve these features, electrochemical sensors can be manufactured by using biodegradable thermoplastic composite electrodes, , screen-printing, − inkjet printing, , laser-scribed graphene (LSG), − among other methods. LSG fabrication has gained great attention in the sensor field due to its excellent properties, such as large surface area, high conductivity, low cost, and simple operation. , Besides, a wide range of substrates can be employed to manufacture electrochemical devices, such as wood, polymers, paper, and nail polish, without the consumption of extra reagents/solvents, providing a greener alternative for manufacturing electrochemical carbon-based devices.…”