Fiber optic nanogold-linked immunosorbent assay for rapid detection of procalcitonin at femtomolar concentration level.

A rapid and ultrasensitive biosensing method based on fiber optic nanogold-linked immunosorbent assay is reported. The method employs an immobilized capture probe on the fiber core surface of an optical fiber and a detection probe conjugated to gold nanoparticles (AuNPs) in a solution. Introduction of a sample containing an analyte and the detection probe into a biosensor chip leads to the formation of a sandwich-like complex of capture probe-analyte-detection probe on the fiber core surface, through which nanoplasmonic absorption of the fiber optic evanescent wave occurs. The performance of this method has been evaluated by its application to the detection of procalcitonin (PCT), an important biomarker for sepsis. In this study, anti-PCT capture antibody is functionalized on an unclad segment of an optical fiber to yield a fiber sensor and anti-PCT detection antibody is conjugated to AuNPs to afford nanoplasmonic probes. The method provides a wide linear response range from 1 pg/mL to 100 ng/mL (5 orders) and an extremely low limit of detection of 95 fg/mL (7.3 fM) for PCT. In addition, the method shows a good correlation in determining PCT in blood plasma with the clinically validated electrochemiluninescent immunoassay. Furthermore, the method is quick (analysis time ≤15 min), requires low-cost instrumentation and sensor chips, and is also potentially applicable to the detection of many other biomarkers.

Highly-branched Cu2O as well-ordered co-reaction accelerator for amplifying electrochemiluminescence response of gold nanoclusters and procalcitonin analysis based on protein bioactivity maintenance.

The point of fabricating ultrasensitive electrochemiluminescence (ECL)-based biosensors should be focused on how to maintain high immune recognition of antigens by antibodies in whole process. That is not effortless due to the structure of the protein can be destroyed root in toxic nanocarriers, excessive cyclic potential and superoxide radicals in coreactant, all of which can lead to reduce the bioactivity of antigen and antibody. In this work, the effect of negative voltage and divers coreactant on protein bioactivity were verified. Based on that, a motivated ECL biosensor with good biocompatibility was fabricated for procalcitonin (PCT) detection using Au nanoclusters (Au NCs) as low-potential cathodic luminophor and K2S2O8 as non-toxic coreactant, respectively. Besides, highly-branched Cu2O was utilized to catalyze K2S2O8 and produce more radical anion SO4•-, which can oxidize Au NCs•- to generate more high-energy-state Au NCs*, thus doubling the ECL intensity to meet the requirements of trace analysis. In addition, protein A (PA) as specific antibody capturer was employed to bind the Fc region of anti-PCT in an orientated way, further maintaining the physiological activity of antibody. As expected, all strategies undoubtedly practically improved the immune recognition of the biosensor and reduced the detection limit to 2.90 fg/mL.

Time-Resolved Digital Immunoassay for Rapid and Sensitive Quantitation of Procalcitonin with Plasmonic Imaging.

Timely diagnosis of acute diseases improves treatment outcomes and saves lives, but it requires fast and precision quantification of biomarkers. Here, we report a time-resolved digital immunoassay based on plasmonic imaging of binding of single nanoparticles to biomarkers captured on a sensor surface. The real-time and high contrast of plasmonic imaging lead to fast and precise counting of the individual biomarkers over a wide dynamic range. We demonstrated the detection principle, evaluated the performance of the method using procalcitonin (PCT) as an example, and achieved a limit of detection of ∼2.8 pg/mL, dynamic range of 4.2-12500 pg/mL, for a total detection time of ∼25 min.

An ultrasensitive electrochemical immunosensor for procalcitonin detection based on the gold nanoparticles-enhanced tyramide signal amplification strategy.

In this study, we established an ultrasensitive electrochemical immunosensor based on the gold nanoparticles-enhanced tyramide signal amplification (AuNPs-TSA) for the detection of procalcitonin (PCT, for discriminating bacterial infections from nonbacterial infections). Firstly, a facilely prepared, well-conducting reduced graphene oxide nanosheets/GNP (rGO-AuNPs) nanocomposite was synthesized and immobilized on the electrode surface to absorb more capture antibodies (Ab1). Next another nanocomposite, acting as a signal tool, was modified with detection antibody (Ab2) and horseradish peroxidase (HRP), and then backfilled by bovine serum albumin (BSA). Because a single AuNP is able to load multiple HRPs and BSAs, a number of tyramine labeled biotins (T-B) could be deposited on the proteins adhering to the surface of AuNPs. Moreover, the high affinity between streptavidin (SA) and biotins significantly increases the loading of streptavidin labeled horseradish peroxidase (SA-HRP). The amplification system which was based on the two nanocomposites mentioned above, effectively amplified the electric current signals. This immunosensor exhibits a wide dynamic detection range from 0.05 ng mL-1 to 100 ng mL-1 and with an ultralow detection limit of 0.1 pg mL-1. We have successfully utilized this immunosensor to quantify the concentration of PCT in human serum samples, and the results suggest its potential use in clinical application.

Removal of Procalcitonin and Selected Cytokines during Continuous Veno-Venous Hemodialysis Using High Cutoff Hemofilters in Patients with Sepsis and Acute Kidney Injury.

INTRODUCTION: The purpose of this study was to evaluate the impact of continuous veno-venous hemodialysis (CVVHD) using high cutoff (HCO) hemofilters on the removal of procalcitonin (PCT), and other inflammatory markers in the treatment of patients during septic shock with acute kidney injury (AKI). MATERIALS AND METHODS: Thirty-six patients with septic shock and AKI were included in the study. Before and after the 24-h HCO-CVVHD, PCT, native C-reactive protein (CRP) and cytokines (interleukin-1ß, interleukin-6, interleukin-12, interleukin-17, tumor necrosis factor-α) in serum and effluent were assessed. RESULTS: After the HCO-CVVHD serum concentrations of PCT, CRP and selected cytokines were significantly lower. The decrease in PCT was bigger than in CRP (p = 0.007). The change in PCT concentration was significantly influenced by PCT and IL-17 clearances (R2 = 0.525; p < 0.001). CONCLUSION: In contrast to the native CRP, monitoring of PCT during HCO-CVVHD is less useful because it reflects the clearance of this marker and anti-inflammatory effectiveness of the method.