ABSTRACT
Determination of circulating tumor cells (CTCs) is crucial for cancer diagnosis and therapy at an early stage. However, extremely low concentration of CTCs in peripheral blood makes the detection of CTCs challenging. In this study, a reusable cytosensor was developed for rapid detection of CTCs based on excellent photoelectrochemical (PEC) characteristic of semiconductor nanoarrays. Using typical breast cancer cell, MCF-7 cell, as a target model, a PEC sensing platform was constructed with polymerized aminophenylboronic acid (APBA) layer coated CdS/ZnO nanorod arrays, exhibiting outstanding performance for the capture and detection of CTCs. In this design, the polymerized APBA provides abundant binding sites for capturing terminal sialic acid (SA) molecules in CTCs. As a result, the PEC cytosensor shows good sensitivity and specificity with concentrations ranging from 50 to 1.0 × 106 cells/mL MCF-7 cells. Moreover, the PEC cytosensor can be rapidly and effectively recovered via a short-time bias triggered cell release and subsequent repair of APBA. This study establishes a new approach to refine a PEC cytosensor for stable monitoring and provides a robust PEC electrode with high sensitivity and low cost for clinical diagnosis related to CTCs.
Subject(s)
Biosensing Techniques , Neoplastic Cells, Circulating , Cell Count , Electrodes , Humans , MCF-7 CellsABSTRACT
Affordable methodologies for detecting tumor markers at low concentrations are very important for early diagnosis. The two key requirements for designing ultrasensitive photoelectrochemical (PEC) immunosensors are highly active PEC platforms and amplified recognition events on the transducer surfaces. Herein we report the development of an effective and general strategy for the sensitive immunoassay of biomarkers using a novel PEC platform. In particular, in contrast to traditional photoanode materials prepared by introducing well-stabilized quantum dots onto an electrode, in this work CdSe nanocrystal (NC)-based PEC films were first formed directly on an ITO surface by an anion-exchange reaction and followed by coverage with organic stabilizers. The compacted CdSe film produces ultrahigh photocurrent signals under visible-light irradiation (λ = 470 nm). Using rabbit immunoglobulin G (RIgG) as a model biomarker, we showed that through biotin-avidin bridges, biotin-functionalized peroxidase (B-HRP) could be further assembled and could catalyze the conversion of its substrate, 4-chloro-1-naphthol (4-CN), to realize precipitation of nonconductive benzo-4-chlorohexadienone on the CdSe surface, thus resulting in blocking of the electron donors and absorption of the incident light. As the resulting photocurrent decrease was directly related to the target concentration, a sensitive PEC immunoassay could be constructed. The target RIgG was detected over a concentration range from 1.0 fg mL-1 to 10 µg mL-1 with an ultralow detection limit of 0.5 fg mL-1. This study presents a promising and general strategy for the development of highly sensitive PEC biosensors, which can be extended to the detection of other enzymes and biomolecules.
ABSTRACT
An immunochromatographic test strip using gold nanoparticles-staphylococcus aureus monoclonal antibody conjugates was developed for the rapid and convenient detection of staphylococcus aureus based on a double-antibody sandwich format. The detection limit and the detection rate of this test strip is 10(3) CFU /mL and 98.7%, respectively. It could be used for the rapid detection of staphylococcus aureus in food and the results can be visually identified by the naked eye within 10 min. Compared with conventional bacterial detection methods, this developed immunochromatographic assay based test strip has several advantages including simple, fast, low-cost, favorable sensitivity and specificity, exhibiting a great potential for application in food safety control systems and clinical diagnosis.
