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Aggregation of alpha-synuclein (aSyn) occurs in presynaptic neurons and constitutes a key factor for the progression of Parkinson's disease, emphasising the urgency of early detection to support effective treatment. Unfortunately, a reliable, sensitive and cost-effective diagnostic tool has so far been lacking. Thus, this work presents a novel biosensor for detecting aSyn using plastic antibodies coupled to electrochemical detection. This biosensor was designed for portability and compatibility with point-of-care devices and exploits the electropolymerization of methylene blue (MB) together with aSyn on the carbon working electrode of screen-printed electrodes (SPEs). By electrochemical impedance spectroscopy (EIS) measurements, the sensor showed exceptional analytical performance in detecting aSyn monomers in human CSF samples. It showed a linear trend of response from 1 fM to 10 pM with an impressively low limit of detection of 69 aM. Selectivity tests confirmed the predominant response to aSyn monomers, a less intense response to oligomers and insensitivity to fibrils. Overall, this plastic antibody-based electrochemical sensor represents a significant breakthrough as it is the first of its kind to accurately, sensitively and selectively detect aSyn monomers with a partial response to oligomers. Its simplicity and reproducibility promise to contribute to the early and effective diagnosis of Parkinson's disease., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Graphene has emerged as a novel material with enhanced electrical and structural properties that can be used for a multitude of applications from super-capacitors to biosensors. In this context, an ultra-sensitive biosensor was developed using a low-cost, simple and mask-free method based on laser-induced graphene technique for electrodes patterning. The graphene was produced on a polyimide substrate, showing a porous multi-layer structure with a resistivity of 102.4 ± 7.3 Ω/square. The biosensor was designed as a 3-electrode system. Auxiliary and working electrodes were made of graphene by laser patterning and the reference electrode was handmade by casting a silver ink. A molecularly-imprinted polymer (MIP) was produced at the working electrode by direct electropolymerization of eriochrome black T (EBT). As proof-of-concept, the MIP film was tailored for chloramphenicol (CAP), a common contaminant in aquaculture. The resulting device was evaluated by cyclic voltammetry and electrochemical impedance spectroscopy readings against a redox standard probe. The limit of detection (LOD) was 0.62 nM and the linear response ranged from 1 nM to 10 mM. These analytical features were better than those produced by assembling the same biorecognition element on commercial graphene- and carbon-based screen-printed electrodes. Overall, the simplicity and quickness of the laser-induced graphene technique, along with the better analytical features obtained with the graphene-based electrodes, shows the potential to become a commercial approach for on-site sensing., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Zika virus (ZIKV) recently emerged as a global threat subsequent to its global spread because it induces microencephaly and other brain damages in infants born to infected mothers. Epidemiological monitoring of infection has been hampered by the absence of reliable serological tests capable to distinguish between ZIKV and other Flavivirus infections, in particular Dengue virus (DENV). As both viruses are transmitted by the same mosquito-species, their distributions largely overlap and reliable serological distinction between the viruses is essential. Here we develop a novel biosensor which is based on recombinant forms of ZIKV non-structural protein 1 (NS1) and the domain III of the envelope protein (EDIII). Using electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SWV), we demonstrate that in addition to extremely sensitive detection of ZIKV-specific antibodies in serum and saliva, the biosensor promptly distinguished ZIKV and DENV-specific antibodies. Hence, this novel biosensor allows assessing ZIKV antibodies in blood and saliva and results are unaffected by presence of DENV virus-specific antibodies., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Sensitive detection of specific antibodies by biosensors has become of major importance for monitoring and controlling epidemics. Here we report a development of a biosensor able to specifically measure antibodies in a drop of unmodified blood serum. Within minutes, the detection system measures presence of antibodies against Plasmodium vivax, a causing agent for malaria. The biosensor consists of a layer of carbon nanotubes (CNTs) which were casted on a carbon working electrode area of a three-electrode system and oxidized. An amine layer was produced next by modifying the surface with EDAC/NHS followed by reaction with a diamine compound. Finally, the protein fragments derived from P. vivax containing well-known antigen sequences were casted on this layer and bound through electrostatic interactions, involving hydrogen and ionic bonding. All these chemical changes occurring at the carbon surface along the biosensor assembly were followed and confirmed by Fourier Transformed Infrared s pectrometry (FTIR) and Raman spectroscopy. The presence of antibodies in serum was detected by monitoring the electrical properties of the layer, making use of cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SWV), against a standard iron probe. Overall, the charge-transfer resistance decreased after antibody binding, because there was an additional amount of protein bound to the surface. This hindered the access of the iron redox probe to the conductive support at the electrode surface. Electrical changes could be measured at antibody concentration as low as ~6-50pg/L (concentrations in the range of 10-15M) and as high as ~70μg/L. Specific measurement with low background was even possible in undiluted serum. Hence, this novel biosensor allows assessing serum antibody levels in real time and in un-manipulated serum samples on-site where needed., (Copyright © 2017 Elsevier B.V. All rights reserved.)

This work, describes for the first time, a simple biosensing design to yield an ultrasensitive electrochemical biosensor for a cancer biomarker detection, miRNA-155, with linear response down to the attomolar range. MiRNA-155 was selected for being overexpressed in breast cancer. The biosensor was assembled in two stages: (1) the immobilization of the anti-miRNA-155 that was thiol modified on an Au-screen printed electrode (Au-SPE), followed by (2) blocking the areas of non-specific binding with mercaptosuccinic acid. Atomic force microscopy (AFM) and electrochemical techniques including cyclic voltammetry (CV), impedance spectroscopy (EIS) and square wave voltammetry (SWV) confirmed the surface modification of these devices and their ability to hybridize successfully and stably with miRNA-155. The final biosensor provided a sensitive detection of miRNA-155 from 10 aM to 1.0 nM with a low detection limit (LOD) of 5.7 aM in real human serum samples. Good results were obtained in terms of selectivity towards breast cancer antigen CA-15.3 and bovine serum albumin (BSA). Raw fluid extracts from cell-lines of melanoma did not affect the biosensor response (no significant change of the blank), while raw extracts from breast cancer yielded a positive signal against miRNA-155. This simple and sensitive strategy is a promising alternative for simultaneous quantitative analysis of multiple miRNA in physiological fluids for biomedical research and point-of-care (POC) diagnosis., (Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.)