Combining 3D graphene-like screen-printed carbon electrode with methylene blue-loaded liposomal nanoprobes for phospholipase A2 detection

Abstract

Phospholipase A 2 (PLA 2) enzyme could be acted as a unique biomarker for forecasting and diagnosing certain diseases. Therefore, it is important to monitor PLA 2 activity in biological and clinical samples. In this work, a simple electrochemical assay for PLA 2 activity was developed based on a screen-printed carbon electrode (SPCE) with 3D graphene-like surface. When the PLA 2-containing sample was mixed with the nanoprobes, i.e. the electroactive marker methylene blue (MB) encapsulated within nanometer-sized phospholipid liposomes, MB was released and adsorbed/enriched in site onto the surface of SPCE in a micro-cell. The encapsulation and enzymatic release of MB were evaluated using UV-Vis and fluorescence. The peak current due to oxidation of the adsorbed MB on the SPCE was measured by square-wave voltammetry (SWV). The current was directly linear to the PLA 2 activity from 5 U/L to 200 U/L with a detection limit of 3 U/L. The same method can also be used for screening PLA 2 inhibitors. Thus, the enrichment strategy developed in this work could be a promising signal amplification method for the sensitive and selective detection of PLA 2 in biological or clinical samples.

“Dual Signal-On” Split-Type Aptasensor for TNF-α: Integrating MQDs/ZIF-8@ZnO NR Arrays with MB-Liposome-Mediated Signal Amplification

“…MB could aggregate reversibly, providing both dimer and monomer forms at a relatively high concentration in an aqueous solution. 50 The absorption at about 610 nm could be dimer absorption resulting from reversible aggregation, thus demonstrating a relatively high concentration of MB inside the liposome. After addition of Triton X-100 into an MLL solution, a noticeably increase in the absorption in the MB monomer peak (660 nm) and a decrease in the MB dimer peak (610 nm) were observed (curve c).…”

“…While in the UV–vis absorption spectrum of MLL (curve b), the characteristic absorbance bands in the range of 610–675 nm can be observed. MB could aggregate reversibly, providing both dimer and monomer forms at a relatively high concentration in an aqueous solution . The absorption at about 610 nm could be dimer absorption resulting from reversible aggregation, thus demonstrating a relatively high concentration of MB inside the liposome.…”

An Electrochemical Strip to Evaluate and to Discriminate Drug Encapsulation in Lipid Nanovectors

“…The release of the electrochemical mediator, and its following detection, was activated by the presence of the target enzyme and its ability to hydrolyze the phospholipid of the liposomes. 28 The same approach based on the use of liposomes as the electrochemical labels has also been reported for the development of other sensing architectures. 29 However, all these works exploit the use of liposomes as electrochemical labels to transduce recognition events, e.g., antibody−antigen, enzyme−substrate, nucleic acid hybridization, while the aim of this Technical Note is to highlight the development of an electrochemical approach to quantify and characterize the efficacy of cargo encapsulation.…”

“…Another work exploited the role of a methylene blue-loaded liposome as an electrochemical label to detect enzyme phospholipase A2. The release of the electrochemical mediator, and its following detection, was activated by the presence of the target enzyme and its ability to hydrolyze the phospholipid of the liposomes . The same approach based on the use of liposomes as the electrochemical labels has also been reported for the development of other sensing architectures .…”

Nanometer-Sized Boron Loaded Liposomes Containing Fe3O4 Magnetic Nanoparticles and Tributyl Borate and Anti-Albumin from Bovine Serum Antibody for Thermal Neutron Detection

“…Liposome is a cellular mimic with artificial membranes, structurally similar to the lipid bilayer and cytomembrane [ 14 , 15 ]. The membrane structure possesses the advantages of convenient surface modification and being functionalized with molecules and biomolecular groups, such as proteins [ 16 , 17 ]. Importantly, these functionalized liposomes have been extensively employed in the development of novel sensors [ 18 , 19 , 20 , 21 ].…”