Modification-free amperometric biosensor for the detection of wild-type p53 protein based on the in situ formation of silver nanoparticle networks for signal amplification

Sensitive and accurate quantification of wild-type p53 protein is of great importance for biological research and clinical diagnosis. Herein, a modification-free amperometric biosensor was proposed for sensitive detection of wild-type p53 protein by the signal amplification of silver nanoparticles (AgNPs) networks formed in situ on electrode surface. Double-stranded DNA (dsDNA) probe containing two consensus sites was immobilized on gold electrode surface to capture wild-type p53 protein. The cysteine thiol and amine groups on the exterior of the protein allowed for the attachment of bare AgNPs through the AgS or AgN interactions. Meanwhile, benzene-1,4-dithiol (BDT) molecules in solution triggered the assembly of more AgNPs on electrode surface through the AgS interactions, thus leading to the in situ formation of AgNPs networks for signal amplification. The target at the concentration as low as 0.1 pM can be readily determined. This method was further applied to determine wild-type p53 protein in spiked human serum and cell lysates with satisfactory results. Moreover, the biosensor is regenerative and does not require the modification of AgNPs with recognition element for signal readout. The modification-free strategy can potentially be applied to develop novel biosensors for detection of other biological macromolecules.

Advances in the Application of Magnetic Nanoparticles for Sensing

Magnetic nanoparticles (MNPs) are of high significance in sensing as they provide viable solutions to the enduring challenges related to lower detection limits and nonspecific effects. The rapid expansion in the applications of MNPs creates a need to overview the current state of the field of MNPs for sensing applications. In this review, the trends and concepts in the literature are critically appraised in terms of the opportunities and limitations of MNPs used for the most advanced sensing applications. The latest progress in MNP sensor technologies is overviewed with a focus on MNP structures and properties, as well as the strategies of incorporating these MNPs into devices. By looking at recent synthetic advancements, and the key challenges that face nanoparticle-based sensors, this review aims to outline how to design, synthesize, and use MNPs to make the most effective and sensitive sensors.

Competitive amperometric immunosensor for determination of p53 protein in urine with carbon nanotubes/gold nanoparticles screen-printed electrodes: A potential rapid and noninvasive screening tool for early diagnosis of urinary tract carcinoma

Since p53 protein has become recognized biomarker for both diagnostic and therapeutic purposes in oncological diseases with particular relevance for bladder cancer, it is highly desirable to search for a novel sensing tool for detecting the patient's p53 level at the early stage. Here we report the first study on the development and validation of a novel disposable competitive amperometric immunosensor for determination of p53 protein at subnanomolar levels, based on p53 immobilization on gold nanoparticles/carbon nanotubes modified screen-printed carbon electrodes. The assay protocol requires the use of single anti-p53 mouse monoclonal antibody (DO-7 clone), able to recognize both wild-type and mutant p53. The developed immunosensor as well as the protocol of the electrochemical immunoassay were optimized by means of an experimental design procedure to assess the suitability of the device to be validated and applied for the determination of p53 in untreated and undiluted urine samples. It was found that the developed competitive immunodevice was able to achieve wide linear range detection of wild-type p53 from 20 pM to 10 nM with a low detection limit of 14 pM in synthetic urine samples, suggesting the sensor's capability of working in a complex sample matrix. The excellent performance results also in terms of selectivity, trueness and precision, coupled with the advantages of an easy preparation and low-cost assay in contrast to other methods which require very complex, time-consuming and costly nanostructured architectures, makes the developed competitive immunosensor an analytically robust diagnostic tool, valuable for implementation of screening and follow-up programs in patients with urologic malignancies.

Construction of portable electrochemical immunosensors based on graphene hydrogel@polydopamine for microcystin-LR detection using multi-mesoporous carbon sphere-enzyme labels

A portable electrochemical immunosensor was fabricated for the detection of microcystin-LR by using graphene hydrogel@polydopamine as the substrate material and multi-HRP-(MCSs/Thi@AuNPs)-Ab₂ as the signal label.