Rapid Colorimetric Determination of Procalcitonin Using Magnetic Separation and Enzymatic Catalysis

Simple and sensitive sandwich-like voltammetric immunosensing of procalcitonin

Procalcitonin (PCT) is a reliable biomarker in the early diagnosis of septicemia, pyemia and stroke-associated pneumonia. In this work, through preparing β-cyclodextrin/graphene (CD/GN) nanohybrid as carrier and amplifier simultaneously to band antibodies and probe molecules, a simple and innovative sandwich-like voltammetric immunosensor was proposed for the sensitive and effective determination of PCT. Owing to the host-guest recognition property, the antibodies of PCT can enter into the CD cavities to generate a stable complex; meanwhile, aminopyrene (AP) were introduced as the signal probe and it was adsorbed on the surface of GN via aminopyrine π-πinteraction. Based on the signal change from AP as a response signal which exhibits linearity to the concentration of PCT, a highly sensitive sandwich-type voltammetric immunosensor was developed successfully after optimizing various key parameters. The results demonstrated that the developed sensor had a considerably low detection limit (0.003 pg mL-1) and wide linearity of 0.01 pg mL-1 to 20.0 ng mL-1. This work offered a very simple and sensitive sensing strategy for PCT and other biomarkers via altering the specific antibodies simply, showing great potential applications.

Nanobiosensors for procalcitonin (PCT) analysis

BACKGROUND

Procalcitonin (PCT) is a critical biomarker that is released in response to bacterial infections and can be used to differentiate the pathogenesis of the infectious process.

OBJECTIVE

In this article, we provide an overview of recent advances in PCT biosensors, highlighting different approaches for biosensor construction, different immobilization methods, advantages and roles of different matrices used, analytical performance, and PCT biosensor construction. Also, we will explain PCT biosensors sensible limits of detection (LOD), linearity, and other analytical characteristics. Future prospects for the development of better PCT biosensor systems are also discussed.

METHODS

Traditional methods such as capillary electrophoresis, high-performance liquid chromatography, and mass spectrometry are effective in analyzing PCT in the medical field, but they are complicated, time-consuming sample preparation, and require expensive equipment and skilled personnel.

RESULTS

In the past decades, PCT biosensors have emerged as simple, fast, and sensitive tools for PCT analysis in various fields, especially medical fields.

CONCLUSION

These biosensors have the potential to accompany or replace traditional analytical methods by simplifying or reducing sample preparation and making field testing easier and faster, while significantly reducing the cost per analysis.

Ultrasensitive Photoelectrochemical Immunoassay Strategy Based on Bi2S3/Ag2S for the Detection of the Inflammation Marker Procalcitonin

As an inflammatory marker, procalcitonin (PCT) is more representative than other traditional inflammatory markers. In this work, a highly efficient photoelectrochemical (PEC) immunosensor was constructed based on the photoactive material Bi₂S₃/Ag₂S to realize the sensitive detection of PCT. Bi₂S₃ was prepared by a hydrothermal method, and Ag₂S quantum dots were deposited on the ITO/Bi₂S₃ surface via in situ reduction. Bi₂S₃ is a kind of admirable photoelectric semiconductor nanomaterial on account of its moderate bandgap width and low binding rate of photogenerated electron holes, which can effectively convert light energy into electrical energy. Therefore, based on the energy level matching principle of Bi₂S₃ and Ag₂S, a labeled Bi₂S₃/Ag₂S PEC immunosensor was constructed, and the sensitive detection of PCT was successfully established. The linear detection range of the PEC immunosensor was 0.50 pg∙mL^-1 to 50 ng∙mL^-1, and the minimum detection limit was 0.18 pg∙mL^-1. Compared with the traditional PEC strategy, the proposed PEC immunosensor is simple, convenient, and has good anti-interference, sensitivity, and specificity, which could provide a meaningful theoretical basis and reference value for the clinical detection of PCT.

Recent advances in nanomaterials-based optical sensors for detection of various biomarkers (inorganic species, organic and biomolecules)

This review briefly emphasizes the different detection approaches (electrochemical sensors, chemiluminescence, surface-enhanced Raman scattering), functional nanostructure materials (quantum dots, metal nanoparticles, metal nanoclusters, magnetic nanomaterials, metal oxide nanoparticles, polymer-based nanomaterials, and carbonaceous nanomaterials) and detection mechanisms. Further, this review emphasis on the integration of functional nanomaterials with optical spectroscopic techniques for the identification of various biomarkers (nucleic acids, glucose, uric acid, oxytocin, dopamine, ascorbic acid, bilirubin, spermine, serotonin, thiocyanate, Pb²⁺ , Cu²⁺ , Hg²⁺ , F^- , peptides, and cancer biomarkers (mucin 1, prostate specific antigen, carcinoembryonic antigen, CA15-3, human epidermal growth factor receptor 2, C-reactive protein, and interleukin-6). Analytical characteristics of nanomaterials-based optical sensors are summarized in Tables, providing the insights of nanomaterials-based optical sensors for biomarkers detection. Finally, the opportunities and challenges of nanomaterials-based optical analytical approaches for the detection of various biomarkers (inorganic, organic, biomolecules, peptides and proteins) are discussed.

Magnetic Bead-Based Electrochemical Immunoassays On-Drop and On-Chip for Procalcitonin Determination: Disposable Tools for Clinical Sepsis Diagnosis

Procalcitonin (PCT) is a known protein biomarker clinically used for the early stages of sepsis diagnosis and therapy guidance. For its reliable determination, sandwich format magnetic bead-based immunoassays with two different electrochemical detection approaches are described: (i) disposable screen-printed carbon electrodes (SPE-C, on-drop detection); (ii) electro-kinetically driven microfluidic chips with integrated Au electrodes (EMC-Au, on-chip detection). Both approaches exhibited enough sensitivity (limit of detection (LOD) of 0.1 and 0.04 ng mL⁻¹ for SPE-C and EMC-Au, respectively; cutoff 0.5 ng mL⁻¹), an adequate working range for the clinically relevant concentrations (0.5–1000 and 0.1–20 ng mL⁻¹ for SPE-C and EMC-Au, respectively), and good precision (RSD < 9%), using low sample volumes (25 µL) with total assay times less than 20 min. The suitability of both approaches was successfully demonstrated by the analysis of human serum and plasma samples, for which good recoveries were obtained (89–120%). Furthermore, the EMC-Au approach enabled the easy automation of the process, constituting a reliable alternative diagnostic tool for on-site/bed-site clinical analysis.

Polymer-Based Micromotor Fluorescence Immunoassay for On-the-Move Sensitive Procalcitonin Determination in Very Low Birth Weight Infants' Plasma

A new fluorescence micromotor-based immunoassay (FMIm) has been developed for procalcitonin (PCT) determination as an early sepsis diagnostic analytical tool. The micromotors combine the high binding capacity of the specific antibodies onto their polymeric polypyrrole outer layer (PPy layer), with their magnetic guidance (Ni layer) and self-propulsion by catalytic generation of oxygen bubbles (PtNP inner layer) to actively recognize the PCT antigen. This FMIm allowed a sensitive (LOD = 0.07 ng mL^-1) and direct PCT determination in clinical samples from very low-birth-weight infants (VLBWI) with sepsis suspicion, using small volumes of sample (25 μL) in a clinically relevant range of concentrations (0.5-150 ng mL^-1). The good agreement between PCT levels obtained by our micromotor-based method and routine immunofluorescence hospital determination demonstrates the feasibility for the analysis in VLBWI samples and its potential as a point-of-care diagnostic tool for sepsis.

Ultrasensitive and selective detection of Staphylococcus aureus using a novel IgY-based colorimetric platform

To develop a specific method for the detection of S. aureus, chicken anti-protein A IgY was adopted for specifically capturing S. aureus, depending on the specific recognition of staphylococcal protein A (SPA) by chicken anti-protein A IgY, which can eliminate the interference from protein G-producing Streptococcus. HRP labeled IgG, Fc region of which has a high affinity towards SPA, was paired with IgY for the colorimeter analysis of the system. By optimizing the system, a super-low detection limit of 11 CFU of S. aureus in 100 μL PBS without enrichment, with a linear range from 5.0 × 10² CFU mL^-1 to 5.0 × 10⁴ CFU mL^-1 was obtained. The entire assay was accomplished in less than 90 min and no cross-reactivity with the other tested bacterial species was observed. Moreover, the developed assay has been applied for the detection of S. aureus in three different types of real samples (sodium chloride injection, apple juice and human urine) with satisfactory results. To the best of our knowledge, it is the first time to report using chicken anti-protein A IgY and any IgG to detect S. aureus based on the dual-recognition mode of SPA. The novel method opened up a way for monitoring S. aureus in food samples with high sensitivity, specificity and simple operation.

A novel colorimetric sensing platform for the detection ofS. aureuswith high sensitivity and specificity

In this study, a novel colorimetric sensing platform was developed for the detection of S. aureus using dog immunoglobulin G (IgG) as the capture antibody and chicken anti-protein A immunoglobulin Y labeled with horseradish peroxidase (HRP-IgY) as the detection antibody. Dog IgG labeled with magnetic beads was used to capture S. aureus through the interaction between the Fc region of dog IgG and Staphylococcal protein A (SPA). HRP-IgY was introduced to recognize the residual SPA on the surface of S. aureus and to create a sandwich format, after which a soluble 3,3′,5,5′-tetramethylbenzidine (TMB) substrate was added. A stop solution was utilized to cease the enzymatic chromogenic reaction, and then optical density was read at 450 nm. Under optimal conditions, the proposed method displayed a low detection limit of 1.0 × 10³ CFU mL⁻¹ and a wide linear range of 3.1 × 10³ to 2.0 × 10⁵ CFU mL⁻¹. This detection method exhibited high specificity against other foodborne bacteria. The recovery rates ranged from 95.2% to 129.2%. To our knowledge, this is the first report to employ dog IgG and chicken IgY as an antibody pair to detect S. aureus. This technique exhibits high application potential for S. aureus monitoring in various kinds of samples.

Utilization of dog IgG and chicken anti-protein A IgY as an antibody pair for sensitive and selective detection of S. aureus.