scholarly journals A colorimetric sensing platform based on self-assembled 3D porous CeGONR nanozymes for label-free visual detection of organophosphate pesticides

2020 ◽  
Vol 1 (8) ◽  
pp. 2789-2796
Author(s):  
Liyun Lin ◽  
Huifang Ma ◽  
Chunliang Yang ◽  
Wuhai Chen ◽  
Shaodong Zeng ◽  
...  
Keyword(s):  
Visual Detection ◽  
Organophosphate Pesticides ◽  
Label Free ◽  
Colorimetric Sensing ◽  
Naked Eye ◽  
Synthetic Strategy ◽  
Sensing Platform ◽  
Self Assembled

A Ce(iii)-driven self-assembled synthetic strategy was developed to fabricate 3D porous nanozymes. A paper-based, naked eye visible, disposable inhibition enzymatic nanoplatform was developed to detect organophosphate pesticides.

scholarly journals Hyperchromatic structural color for perceptually enhanced sensing by the naked eye

2020 ◽  
Vol 117 (48) ◽  
pp. 30107-30117
Author(s):  
Tahmid H. Talukdar ◽  
Bria McCoy ◽  
Sarah K. Timmins ◽  
Taufiquar Khan ◽  
Judson D. Ryckman
Keyword(s):  
High Performance ◽  
Limit Of Detection ◽  
Form Factors ◽  
Optical Filters ◽  
Color Filter ◽  
Structural Color ◽  
Label Free ◽  
Colorimetric Sensing ◽  
Large Area ◽  
Naked Eye

Colorimetric sensors offer the prospect for on-demand sensing diagnostics in simple and low-cost form factors, enabling rapid spatiotemporal inspection by digital cameras or the naked eye. However, realizing strong dynamic color variations in response to small changes in sample properties has remained a considerable challenge, which is often pursued through the use of highly responsive materials under broadband illumination. In this work, we demonstrate a general colorimetric sensing technique that overcomes the performance limitations of existing chromatic and luminance-based sensing techniques. Our approach combines structural color optical filters as sensing elements alongside a multichromatic laser illuminant. We experimentally demonstrate our approach in the context of label-free biosensing and achieve ultrasensitive and perceptually enhanced chromatic color changes in response to refractive index changes and small molecule surface attachment. Using structurally enabled chromaticity variations, the human eye is able to resolve ∼0.1-nm spectral shifts with low-quality factor (e.g., Q ∼ 15) structural filters. This enables spatially resolved biosensing in large area (approximately centimeters squared) lithography-free sensing films with a naked eye limit of detection of ∼3 pg/mm2, lower than industry standard sensors based on surface plasmon resonance that require spectral or angular interrogation. This work highlights the key roles played by both the choice of illuminant and design of structural color filter, and it offers a promising pathway for colorimetric devices to meet the strong demand for high-performance, rapid, and portable (or point-of-care) diagnostic sensors in applications spanning from biomedicine to environmental/structural monitoring.

DNA base-stacking assay utilizing catalytic hairpin assembly-induced gold nanoparticle aggregation for colorimetric protein sensing

2016 ◽  
Vol 52 (22) ◽  
pp. 4167-4170 ◽  
Author(s):  
Chia-Chen Chang ◽  
Chie-Pein Chen ◽  
Chen-Yu Chen ◽  
Chii-Wann Lin
Keyword(s):  
Gold Nanoparticle ◽  
Label Free ◽  
Colorimetric Sensing ◽  
Base Stacking ◽  
Nanoparticle Aggregation ◽  
Protein Sensing ◽  
Sensing Platform ◽  
Dna Base ◽  
Gold Nanoparticle Aggregation ◽  
Catalytic Hairpin Assembly

A label-free and enzyme-free colorimetric sensing platform for the amplified detection of fibronectin was developed based on an ingenious combination of catalytic hairpin assembly and a base stacking hybridization-based gold nanoparticle aggregation strategy.

Ionic liquid tuned titanium dioxide nanostructures as an efficient colorimetric sensing platform for dopamine detection

2021 ◽  
Vol 262 ◽  
pp. 124289
Author(s):  
Umar Nishan ◽  
Ujala Sabba ◽  
Abdur Rahim ◽  
Muhammad Asad ◽  
Mohibullah Shah ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Titanium Dioxide ◽  
Colorimetric Sensing ◽  
Dopamine Detection ◽  
Sensing Platform

scholarly journals Microfluidic Impedance Biosensor Chips Using Sensing Layers Based on DNA-Based Self-Assembled Monolayers for Label-Free Detection of Proteins

Biosensors ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 80
Author(s):  
Khaled Alsabbagh ◽  
Tim Hornung ◽  
Achim Voigt ◽  
Sahba Sadir ◽  
Taleieh Rajabi ◽  
...  
Keyword(s):  
Troponin I ◽  
Electrochemical Impedance ◽  
Specific Binding ◽  
Self Assembled Monolayers ◽  
Significant Shift ◽  
Label Free ◽  
Label Free Detection ◽  
Assembled Monolayers ◽  
Self Assembled ◽  
Biosensor Chip

A microfluidic chip for electrochemical impedance spectroscopy (EIS) is presented as bio-sensor for label-free detection of proteins by using the example of cardiac troponin I. Troponin I is one of the most specific diagnostic serum biomarkers for myocardial infarction. The microfluidic impedance biosensor chip presented here consists of a microscope glass slide serving as base plate, sputtered electrodes, and a polydimethylsiloxane (PDMS) microchannel. Electrode functionalization protocols were developed considering a possible charge transfer through the sensing layer, in addition to analyte-specific binding by corresponding antibodies and reduction of nonspecific protein adsorption to prevent false-positive signals. Reagents tested for self-assembled monolayers (SAMs) on gold electrodes included thiolated hydrocarbons and thiolated oligonucleotides, where SAMs based on the latter showed a better performance. The corresponding antibody was covalently coupled on the SAM using carbodiimide chemistry. Sampling and measurement took only a few minutes. Application of a human serum albumin (HSA) sample, 1000 ng/mL, led to negligible impedance changes, while application of a troponin I sample, 1 ng/mL, led to a significant shift in the Nyquist plot. The results are promising regarding specific detection of clinically relevant concentrations of biomarkers, such as cardiac markers, with the newly developed microfluidic impedance biosensor chip.

scholarly journals Ce-MOF with Intrinsic Haloperoxidase-Like Activity for Ratiometric Colorimetric Detection of Hydrogen Peroxide

Biosensors ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 204
Author(s):  
Yanyan Cheng ◽  
Ling Liang ◽  
Fanggui Ye ◽  
Shulin Zhao
Keyword(s):  
Structural Characteristics ◽  
Metal Organic Framework ◽  
Colorimetric Detection ◽  
Mixed Valence ◽  
Bromophenol Blue ◽  
Phenol Red ◽  
Chromogenic Substrate ◽  
Colorimetric Sensing ◽  
Sensing Platform ◽  
Metal Organic

Metal–organic framework (MOF) nanozymes, as emerging members of the nanozymes, have received more and more attention due to their composition and structural characteristics. In this work, we report that mixed-valence state Ce-MOF (MVCM) has intrinsic haloperoxidase-mimicking activity. MVCM was synthesized by partial oxidation method using Ce-MOF as a precursor. In the presence of H2O2 and Br−, MVCM can catalyze oxidative bromination of chromogenic substrate phenol red (PR) to produce the blue product bromophenol blue (Br4PR), showing good haloperoxidase-like activity. Because of the special chromogenic substrate, we constructed a ratiometric colorimetric-sensing platform by detecting the absorbance of the MVCM-(PR, Br−) system at wavelengths of 590 and 430, for quantifying H2O2, where the detection limit of the H2O2 is 3.25 μM. In addition, the haloperoxidase-mimicking mechanism of the MVCM is proposed. Moreover, through enzyme kinetics monitoring, the Km (H2O2 and NH4Br) of the MVCM is lower than that of cerium oxide nanomaterials, indicating that the MVCM has a stronger binding affinity for H2O2 and NH4Br than other materials. This work provides more application prospects for the development of nanozymes in the field of biosensors in the future.

scholarly journals Development of a Novel Label-Free and High-Throughput Arginase-1 Assay Using Self-Assembled Monolayer Desorption Ionization Mass Spectrometry

2021 ◽  
pp. 247255522110006
Author(s):  
Michael D. Scholle ◽  
Zachary A. Gurard-Levin
Keyword(s):  
Mass Spectrometry ◽  
Drug Discovery ◽  
High Throughput ◽  
Ionization Mass Spectrometry ◽  
Ionization Mass ◽  
Label Free ◽  
Desorption Ionization ◽  
Arginase 1 ◽  
Self Assembled ◽  
High Throughput Assay

Arginase-1, an enzyme that catalyzes the reaction of L-arginine to L-ornithine, is implicated in the tumor immune response and represents an interesting therapeutic target in immuno-oncology. Initiating arginase drug discovery efforts remains a challenge due to a lack of suitable high-throughput assay methodologies. This report describes the combination of self-assembled monolayers and matrix-assisted laser desorption ionization mass spectrometry to enable the first label-free and high-throughput assay for arginase activity. The assay was optimized for kinetically balanced conditions and miniaturized, while achieving a robust assay (Z-factor > 0.8) and a significant assay window [signal-to-background ratio > 20] relative to fluorescent approaches. To validate the assay, the inhibition of the reference compound nor-NOHA (Nω-hydroxy-nor-L-arginine) was evaluated, and the IC50 measured to be in line with reported results (IC50 = 180 nM). The assay was then used to complete a screen of 175,000 compounds, demonstrating the high-throughput capacity of the approach. The label-free format also eliminates opportunities for false-positive results due to interference from library compounds and optical readouts. The assay methodology described here enables new opportunities for drug discovery for arginase and, due to the assay flexibility, can be more broadly applicable for measuring other amino acid–metabolizing enzymes.

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