Biosensors, small devices enabling selective bioanalysis because of properly assembled biological recognition molecules, represent the fortuitous results of years of interdisciplinary and complementary investigations in different fields of science. The ultimate role of a biosensor is to provide coupling between the recognition element and the analyte of interest, bringing a quantitative value of its concentrations into a complex sample matrix. They offer many advantages. Among them, portability, low cost with fast response times, and the possibility to operate in situ without the need for sample preparation are certainly the most important. Among biosensors, a large space is occupied by DNA biosensors. Screening genomic DNA is of fundamental importance for the development of new tools available to physicians during the clinical process. Sequencing of individual human genomes, accomplished principally by microarrays with optical detection, is complex and expensive for current clinical protocols. Efforts in research are focused on simplifying and reducing the cost of DNA biosensors. For this purpose, other transduction techniques are under study to make more portable and affordable DNA biosensors. Compared with traditional optical detection tools, electrochemical methods allow the same sensitivity and specificity but are less expensive and less labor intensive. Scalability of electrochemical devices makes it possible to use the advantages introduced by nanosized components. The involvement of nanomaterials and nanostructures with custom-tailored shapes and properties is expected to rapidly boost the field of electrochemical DNA biosensors and, in general, that of next-generation sequencing technologies.
Although promising, organic microelectronics lacks standard fabrication methods comparable to photolithography in terms of resolution. Here we propose a novel and easily scalable on-surface biocatalytical procedure for the fabrication of polypyrrole microelectrodes on insulating surfaces. Arrays of polypyrrole microelectrodes were obtained by surface-guided biocatalytical polymerization, achieving up to 5 [small micro]m in resolution and conductivities up to 3 S cm-1. The mild reaction conditions provided by the biocatalytical approach permit the entrapment of bioactive compounds during polymer synthesis. This system is convenient for drug release purposes, as demonstrated by the controlled release of entrapped biotin through electrical stimulation. These results pave the way for the application of polypyrrole microelectrodes produced through biocatalysis in the development of implantable devices for remotely controlled tissue interactions.