An electrochemical device to control sample pH locally in Lab-on-PCB devices: An investigation into spatial resolution

Abstract

During the recent pandemic outbreak, Lab-on-Chip devices did not manage to fully reach their potential in rapid diagnosis of pathogens, mainly due to the lack of cost-effective LoC solutions integrated with all required sample preparation modules. This paper presents such a critical step, aiming to translate electrochemical pH control into practical protein preconcentration modules, easy to integrate with subsequent quantification modules seamlessly via Lab-on-PCB technology. In this work we present a device capable of electrochemically controlling the pH of a solution local to an individually addressed electrode in a PCB array. The electrodes were functionalised with an electropolymerised self-assembled monolayer of 4-Aminothiophenol and were subjected to voltages of 0.2–0.4 V, evaluating for the first time the bias effect both over time and over space. This study enables for the first time the implementation of this technique for electrochemical pH control into practical Lab-on-PCB devices such as isoelectric focusing, via the informed design of such electrode arrays of appropriate size and spacing.

Fluorescence Labeling of Peptides: Finding the Optimal Protocol for Coupling Various Dyes to ATCUN-like Structures

“…7 Notably, cyclization of FAM has also been reported; however, the pH window under which FAM is in the open, fluorescent form is between 6 and 9, enhancing its applicability in biological assays. 6,8 4,4-Difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) being another widely applied fluorescent core has also found application in many different fields. 9 Due to their generally relatively sharp fluorescence peaks, high quantum yields, and additional insensitivity to pH and other environmental conditions, prematurely, they have found great application in biological studies and are widely used to label peptides and proteins.…”

“…When FAM is coupled to the N-terminus of a peptide forming an amide bond, its two carboxylic acids result in the possibility of the formation of two inseparable isomers; however, it was shown that incorporation of FAM can result in an increase in sensitivity compared to the other commonly used fluorescein derivative, fluorescein isothiocyanate (FITC), making it a viable alternative to RhoB and FITC . Notably, cyclization of FAM has also been reported; however, the pH window under which FAM is in the open, fluorescent form is between 6 and 9, enhancing its applicability in biological assays. , 4,4-Difluoro-4-bora-3a,4a-diaza- s -indacene (BODIPY) being another widely applied fluorescent core has also found application in many different fields . Due to their generally relatively sharp fluorescence peaks, high quantum yields, and additional insensitivity to pH and other environmental conditions, prematurely, they have found great application in biological studies and are widely used to label peptides and proteins. − For our application, the BODIPY core can be modified to carry a carboxylic acid on one of its pyrrole functionalities, giving rise to BODIPY-FL-propanoic acid (Figure a), , which can be directly applied for amide bond formation in peptide synthesis.…”