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The method of transferring the immunoreaction from electrode surface to tube can greatly improve the analytical performance of electrochemical immunosensor. In this work, based on PtCu nanoprobe-mediated and iodide-catalyzed cascade reaction, an improved electrochemical immunosensor was elaborately designed for neuron-specific enolase (NSE) detection. PtCu nanoparticles combined with NSE antibody (Ab 2 ) were used as immunoprobes to trigger cascade reaction. With high catalytic activity towards the oxidation of iodide, PtCu nanoprobes catalyzed iodide to iodine in the presence of H 2 O 2 , leading to the decrease of iodide. Subsequently, as a bridge between the tube and iodide-responsive sensing interface, the residual iodide in tube was employed to catalyze the transition from thiol substances (RSH) to disulfide substances (RSSR) on electrode surface. On the basis of this property, thiol-modified DNA (DNA-SH) and 6-mercaptohexanol (MCH) reacted with H 2 O 2 and the residual iodide to form disulfide substances and detach from the electrode surface, causing the decrease of interface resistance in different degrees. Then square wave voltammetry (SWV) was applied for current signal of electrochemical sensing interface to achieve the quantitative detection of NSE. Under optimal conditions, this improved biosensor demonstrated excellent selectivity, stability and reproducibility with wide linear range from 0.0001 to 100 ng mL -1 and ultralow detection limit of 52.14 fg mL -1 for NSE, thus holding great promise for sensitive determination of tumor markers., (Copyright © 2019 Elsevier B.V. All rights reserved.)

We propose the first black phosphorus (BP) - fiber optic biosensor for ultrasensitive diagnosis of human neuron-specific enolase (NSE) cancer biomarkers. A novel optical-nano configuration has been exploited by integrating BP nanosheets with a largely tilted fiber grating (BP-TFG), where the BP is bio-functionalized by the poly-L-lysine acting as a critical cross-linker to facilitate bio-nano-photonic interface with extremely enhanced light-matter interaction. BP nanosheets are synthesized by a liquid ultrasonication-based exfoliation and deposited on fiber device by an in-situ layer-by-layer method. The BP-induced optical modulation effects in terms of thickness-tunable feature, polarization-dependence and enhanced light-matter interaction are experimentally investigated. The anti-NSE immobilized BP-TFG biosensor has been implemented to detect NSE biomarkers demonstrating ultrahigh sensitivity with limit of detection down to 1.0 pg/mL, which is 4 orders magnitude lower than NSE cut-off value of small cell lung cancer. The enhanced sensitivity of BP-TFG is 100-fold higher than graphene oxide or AuNPs based biosensors. We believe that BP-fiber optic configuration opens a new bio-nano-photonic platform for the applications in healthcare, biomedical, food safety and environmental monitoring., (Copyright © 2019 Elsevier B.V. All rights reserved.)

This research aims to engineer molecularly imprinted polymer (MIP)-based synthetic receptors for the molecular recognition of neuron specific enolase (NSE) biomarker. The synthetic peptide derived from the NSE was synthesized along with its cysteine and histidine modified versions. The modified peptides were utilized as templates for molecular imprinting, which was achieved by combination of epitope- and electrochemical surface imprinting strategy. The subsequently generated imprinted cavities were used for the detection of the NSE derived peptide and NSE. The imprints created with cysteine (CME) and histidine modified epitopes (HME) could detect the peptide in a concentration range of 2-128 µM and 15.6 nM to 128 µM, respectively. The recognition of NSE was achieved by the same imprints in a linear range of 1-64 ng mL -1 (CME) and 0.25-64 ng mL -1 (HME), respectively. The target molecules bound to the control polymer very weakly, confirming the high selectivity of the MIP cavities. Selectivity studies resulted in imprinting factors of 8.8 and 11 for the CME and HME imprints, respectively. The affinity analyses provided dissociation constants of 2.3 × 10 -10 M and 3 × 10 -11 M for NSE recognition using the corresponding epitope imprints. Cross-reactivity studies with non-specific molecules proved high specificity of the artificial receptors for the targets., (Copyright © 2018 Elsevier B.V. All rights reserved.)

A molecularly imprinted electrochemical sensor for neuron specific enolase (NSE) was developed by electrochemical polymerizing ionic liquid, which was functionalized with pyrrole moiety, in between gold nanoarrays. A well-defined 3D structured gold nanoarray was fabricated on a glassy carbon electrode (GCE) surface by using template-assisted electrochemical deposition technique. 1-(3-mercaptopropyl)-3-vinyl-imidazolium tetrafluoroborate was self-assembled onto the surface of gold nanoarrays to produce active sites for anchoring the molecularly imprinted film. Subsequently, an electrochemical polymerization procedure was carried out in an aqueous solution containing 1,3-di(3-N-pyrrolpropyl)imidazolium bromine ionic liquid and neuron specific enolase (NSE). After removing NSE templates, a molecularly imprinted sensor was successfully fabricated. The sensor showed high selectivity and sensitivity towards NSE, produced a linear response in the concentration range from 0.01 to 1.0ngmL -1 and had a detection limit of 2.6pgmL -1 with an incubation time of 15min. The developed sensor was demonstrated successful in determining NSE in clinical serum samples., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Neuron-specific enolase (NSE) had clinical significance on diagnosis, staging, monitoring effect and judging prognosis of small cell lung cancer. Thus, there had a growing demand for the on-site testing of NSE. Here, a wireless point-of-care testing (POCT) system with electrochemical measurement for NSE detection was developed and verified. The wireless POCT system consisted of microfluidic paper-based analytical devices (μPADs), electrochemical detector and Android's smartphone. Differential pulse voltammetry (DPV) measurement was adopted by means of electrochemical detector which including a potentiostat and current-to-voltage converter. μPADs were modified with nanocomposites synthesized by Amino functional graphene, thionine and gold nanoparticles (NH 2 -G/Thi/AuNPs) as immunosensors for NSE detection. Combined with μPADs, the performance of the wireless POCT system was evaluated. The peak currents showed good linear relationship of the logarithm of NSE concentration ranging from 1 to 500ngmL -1 with the limit of detection (LOD) of 10pgmL -1 . The detection results were automatically stored in EEPROM memory and could be displayed on Android's smartphone through Bluetooth in real time. The detection results were comparable to those measured by a commercial electrochemical workstation. The wireless POCT system had the potential for on-site testing of other tumor markers., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Novel synthetic peptides represent smart molecules for antigen-antibody interactions in several bioanalytics applications, from purification to serum screening. Their immobilization onto a solid phase is considered a key point for sensitivity increasing. In this view, we exploited Quartz Crystal Microbalance with simultaneous frequency and dissipation monitoring (QCM-D) with a double aim, specifically, as investigative tool for spacers monolayer assembling and its functional evaluation, as well as high sensitive method for specific immunosorbent assays. The method was applied to pancreatic ductal adenocarcinoma (PDAC) detection by studying the interactions between synthetic phosphorylated and un-phosphorylated α-enolase peptides with sera of healthy and PDAC patients. The synthetic peptides were immobilized on the gold surface of the QCM-D sensor via a self-assembled alkanethiol monolayer. The presented experimental results can be applied to the development of surfaces less sensitive to non-specific interactions with the final target to suggest specific protocols for detecting PDAC markers with un-labeled biosensors., (Copyright © 2012 Elsevier B.V. All rights reserved.)