A Novel Redox‐free Immunosensor Concept Based on Cobalt Phthalocyanine@carbon Nanotubes Pseudocapacitor for Cardiac B‐type Natriuretic Peptide Detection

An impedimetric immunosensor based on chitosan-Au nanoparticles-reduced graphene oxide nanosheet composite modified PG electrode for detection of brain natriuretic peptide

An ultrasensitive impedimetric immunosensor was developed to detect brain natriuretic peptide (BNP) for early diagnosis of heart failure. To construct this immunosensor, anti-BNP antibodies were immobilized covalently onto nanocomposite of chitosan-Au nanoparticles and reduced graphene oxide nanosheets (CHIT-Au@rGONs) electrodeposited onto pencil graphite electrode. This approach impedes charge transfer resistance (Rct) value proportionally to the BNP captured by antigen-antibody interactions. The observed Rct values by this immunosensor, were correlated with linear concentrations of BNP in the range, 1 × 10-2 to 1 × 103 pg/mL, with a limit of detection of 12 pg/mL and limit of quantification of 36.3 pg/mL. The immunosensor detected BNP in spiked human sera. The analytic recovery of added BNP in human sera was 97.04%. The present method was fairly consistent with commercial approach. The working electrode was stored for 2 months in cold. BSA-IgG had no interference in the electrode activity showing its high specificity for BNP. This novel approach provided a new POC-diagnostics, as direct sample measurements are easier and more efficient by this immunosensor compared to existing immunosensors.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-023-03704-x.

A Redox-Probe-Free Immunosensor Based on Electrocatalytic Prussian Blue Nanostructured Film One-Step-Prepared for Zika Virus Diagnosis

The Zika virus (ZIKV) is a great concern for global health due to its high transmission, including disseminating through blood, saliva, urine, semen and vertical transmission. In some cases, ZIKV has been associated with microcephaly, neurological disorders, and Guillain−Barré syndrome. There is no vaccine, and controlling the disease is a challenge, especially with the co-circulation of the Dengue virus, which causes a severe cross-reaction due to the similarity between the two arboviruses. Considering that electrochemical immunosensors are well-established, sensitive, and practical tools for diagnosis, in this study we developed a sensor platform with intrinsic redox activity that facilitates measurement readouts. Prussian blue (PB) has a great ability to form electrocatalytic surfaces, dispensing redox probe solutions in voltammetric measurements. Herein, PB was incorporated into a chitosan−carbon nanotube hybrid, forming a nanocomposite that was drop-casted on a screen-printed electrode (SPE). The immunosensor detected the envelope protein of ZIKV in a linear range of 0.25 to 1.75 µg/mL (n = 8, p < 0.01), with a 0.20 µg/mL limit of detection. The developed immunosensor represents a new method for electrochemical measurements without additional redox probe solutions, and it is feasible for application in point-of-care diagnosis.

Electroanalytical point-of-care detection of gold standard and emerging cardiac biomarkers for stratification and monitoring in intensive care medicine - a review

Determination of specific cardiac biomarkers (CBs) during the diagnosis and management of adverse cardiovascular events such as acute myocardial infarction (AMI) has become commonplace in emergency department (ED), cardiology and many other ward settings. Cardiac troponins (cTnT and cTnI) and natriuretic peptides (BNP and NT-pro-BNP) are the preferred biomarkers in clinical practice for the diagnostic workup of AMI, acute coronary syndrome (ACS) and other types of myocardial ischaemia and heart failure (HF), while the roles and possible clinical applications of several other potential biomarkers continue to be evaluated and are the subject of several comprehensive reviews. The requirement for rapid, repeated testing of a small number of CBs in ED and cardiology patients has led to the development of point-of-care (PoC) technology to circumvent the need for remote and lengthy testing procedures in the hospital pathology laboratories. Electroanalytical sensing platforms have the potential to meet these requirements. This review aims firstly to reflect on the potential benefits of rapid CB testing in critically ill patients, a very distinct cohort of patients with deranged baseline levels of CBs. We summarise their source and clinical relevance and are the first to report the required analytical ranges for such technology to be of value in this patient cohort. Secondly, we review the current electrochemical approaches, including its sub-variants such as photoelectrochemical and electrochemiluminescence, for the determination  of important CBs highlighting the various strategies used, namely the use of micro- and nanomaterials, to maximise the sensitivities and selectivities of such approaches. Finally, we consider the challenges that must be overcome to allow for the commercialisation of this technology and transition into intensive care medicine.