Recent advances in cytochrome c biosensing technologies

This review is an attempt, for the first time, to describe advancements in sensing technology for cytochrome c (cyt c) detection, at point-of-care (POC) application. Cyt c, a heme containing metalloprotein is located in the intermembrane space of mitochondria and released into bloodstream during pathological conditions. The release of cyt c from mitochondria is a key initiative step in the activation of cell death pathways. Circulating cyt c levels represents a novel in-vivo marker of mitochondrial injury after resuscitation from heart failure and chemotherapy. Thus, cyt c detection is not only serving as an apoptosis biomarker, but also is of great importance to understand certain diseases at cellular level. Various existing techniques such as enzyme-linked immunosorbent assays (ELISA), Western blot, high performance liquid chromatography (HPLC), spectrophotometry and flow cytometry have been used to estimate cyt c. However, the implementation of these techniques at POC application is limited due to longer analysis time, expensive instruments and expertise needed for operation. To overcome these challenges, significant efforts are being made to develop electrochemical biosensing technologies for fast, accurate, selective, and sensitive detection of cyt c. Presented review describes the cutting edge technologies available in the laboratories to detect cyt c. The recent advancements in designing and development of electrochemical cyt c biosensors for the quantification of cyt c are also discussed. This review also highlights the POC cyt c biosensors developed recently, that would prove of interest to biologist and therapist to get real time informatics needed to evaluate death process, diseases progression, therapeutics and processes related with mitochondrial injury.

Immunosensor for trace penicillin G detection in milk based on supported bilayer lipid membrane modified with gold nanoparticles

In this work, we developed an immunosensor for electrochemical detection of penicillin G at trace level. The biosensor was fabricated by immobilizing anti-penicillin G in a supported bilayer lipid membrane (s-BLM) modified with gold nanoparticles, and the modified electrodes were characterized by the scanning electron microscope (SEM), cyclic voltammetry and electrochemical impedance spectroscopy. The biosensor was able to detect penicillin G with a linear correlation ranging from 3.34×10(-3)ng/L to 3.34×10(3)ng/L and a detection limit of 2.7×10(-4)ng/L, much lower than the maximum residue limit (MRL) of penicillin G in milk (4ppb, equal to 4×10(3)ng/L) set out by the European Union. The mean coefficient variation (CV) of the intra-assays and the inter-assays were 5.4% and 7.7%, respectively. In addition, the concentration of penicillin G in milk samples determined by this biosensor was in good agreement with that determined by high performance liquid chromatography (HPLC) assay.

A novel VS2nanosheet-based biosensor for rapid fluorescence detection of cytochrome c

A VS₂/aptamer-based cytochromecsensor was successfully constructed by first applying the DNA-adsorbing ability/fluorescence-quenching properties of VS₂in bioanalysis.

A biomimetic platform to study the interactions of bioelectroactive molecules with lipid nanodomains

In this work, we developed a biomimetic platform where the study of membrane associated redox processes and high-resolution imaging of lipid nanodomains can be both performed, based on a new functional gold modification, l-cysteine self-assembled monolayer. This monolayer proved to be ideal for the preparation of defect-free planar supported lipid bilayers (SLBs) where nanodomains with height difference of ∼1.5 nm are clearly resolved by atomic force microscopy. Single and multicomponent lipid compositions were used, leading to the formation of different phases and domains mimicking the lateral organization of cellular membranes, and in all cases stable and continuous bilayers were obtained. These platforms were tested toward the interaction with bioelectroactive molecules, the antioxidant quercetin, and the hormone epinephrine. Despite the weak interaction detected between epinephrine and lipid bilayers, our biomimetic interface was able to sense the redox process of membrane-bound epinephrine, obtain its surface concentration (9.36 × 10(-11) mol/cm(2) for a fluid bilayer), and estimate a mole fraction membrane/water partition coefficient (Kp) from cyclic voltammetric measurements (1.13 × 10(4) for a fluid phase membrane). This Kp could be used to quantitatively describe the minute changes observed in the photophysical properties of epinephrine intrinsic fluorescence upon its interaction with liposome suspensions. Moreover, we showed that the lipid membrane stabilizes epinephrine structure, preventing its oxidation, which occurs in neutral aqueous solution, and that epinephrine partition and mobility in membranes depends on lipid phase, expanding our knowledge on hormone membrane interactions.

Designing label-free electrochemical immunosensors for cytochrome c using nanocomposites functionalized screen printed electrodes

We have designed here a label-free direct electrochemical immunosensor for the detection of cytochrome c (cyt c), a heme containing metalloprotein using its specific monoclonal antibody. Two nanocomposite-based electrochemical immunosensor platforms were evaluated for the detection of cyt c; (i) self-assembled monolayer (SAM) on gold nanoparticles (GNP) in polypyrrole (PPy) grafted screen printed electrodes (SPE) and (ii) carbon nanotubes (CNT) integrated PPy/SPE. The nanotopologies of the modified electrodes were confirmed by scanning electron microscopy. Electrochemical impedance spectroscopy and cyclic voltammetry were employed to monitor the stepwise fabrication of the nanocomposite immunosensor platforms. In the present method, the label-free quantification of cyt c is based on the direct electron transfer between Fe (III)/Fe (II)-heme redox active site of cyt c selectively bound to anti-cyt c nanocomposite modified SPE. GNP/PPy and CNT/PPy nanocomposites promoted the electron transportation through the conductive pore channels. The overall analytical performance of GNP/PPy based immunosensor (detection limit 2 nM; linear range: 2 nM to 150 µM) was better than the anti-cyt c/CNT/PPy (detection limit 10 nM; linear range: 10 nM to 50 µM). Further, the measurement of cyt c release in cell lysates of cardiomyocytes using the GNP/PPy based immunosensor gave an excellent correlation with standard ELISA.