scholarly journals Colorimetric Sensing with Gold Nanoparticles on Electrowetting-Based Digital Microfluidics

Micromachines ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1423
Author(s):  
Zhen Gu ◽  
Jing-Jing Luo ◽  
Le-Wei Ding ◽  
Bing-Yong Yan ◽  
Jia-Le Zhou ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Low Cost ◽  
Digital Microfluidics ◽  
High Sensitivity ◽  
Bulk Solution ◽  
Label Free ◽  
Colorimetric Sensing ◽  
Wide Range ◽  
The Stability ◽  
Digital Microfluidic

Digital microfluidic (DMF) has been a unique tool for manipulating micro-droplets with high flexibility and accuracy. To extend the application of DMF for automatic and in-site detection, it is promising to introduce colorimetric sensing based on gold nanoparticles (AuNPs), which have advantages including high sensitivity, label-free, biocompatibility, and easy surface modification. However, there is still a lack of studies for investigating the movement and stability of AuNPs for in-site detection on the electrowetting-based digital microfluidics. Herein, to demonstrate the ability of DMF for colorimetric sensing with AuNPs, we investigated the electrowetting property of the AuNPs droplets on the hydrophobic interface of the DMF chip and examined the stability of the AuNPs on DMF as well as the influence of evaporation to the colorimetric sensing. As a result, we found that the electrowetting of AuNPs fits to a modified Young–Lippmann equation, which suggests that a higher voltage is required to actuate AuNPs droplets compared with actuating water droplets. Moreover, the stability of AuNPs was maintained during the processing of electrowetting. We also proved that the evaporation of droplets has a limited influence on the detections that last several minutes. Finally, a model experiment for the detection of Hg2+ was carried out with similar results to the detections in bulk solution. The proposed method can be further extended to a wide range of AuNPs-based detection for label-free, automatic, and low-cost detection of small molecules, biomarkers, and metal ions.

Cocaine detection using aptamer and molybdenum disulfide-gold nanoparticle-based sensors

Nanomedicine ◽  
2020 ◽  
Vol 15 (4) ◽  
pp. 325-335
Author(s):  
Li Gao ◽  
Wenwen Xiang ◽  
Zebin Deng ◽  
Keqing Shi ◽  
Huixing Wang ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Detection Limit ◽  
Molybdenum Disulfide ◽  
Low Cost ◽  
High Sensitivity ◽  
Label Free ◽  
Sensing System ◽  
Plasmon Resonance Band ◽  
Resonance Band ◽  
Cocaine Detection

Aim: The current work highlighted a novel colorimetric sensor based on aptamer and molybdenum disulfide (MoS2)-gold nanoparticles (AuNPs) that was developed for cocaine detection with high sensitivity. Materials & methods: Due to the presence of the plasmon resonance band on the surface of AuNPs, AuNPs aggregated and the color was changed from red to blue after adding a certain concentration of NaCl. We used MoS2 to optimize the sensing system of AuNPs. The folded conformation of the aptamer in combination with cocaine enhanced the salt tolerance of the MoS2-AuNPs, effectively preventing their aggregation. Results & conclusion: The detection limit of cocaine was 7.49 nM with good selectivity. The method based on MoS2-AuNPs colorimetry sensor is simple, quick, label-free and low cost.

scholarly journals Label-Free Assays on the BIND System

2004 ◽  
Vol 9 (6) ◽  
pp. 481-490 ◽  
Author(s):  
Brian T. Cunningham ◽  
Peter Li ◽  
Stephen Schulz ◽  
Bo Lin ◽  
Cheryl Baird ◽  
...  
Keyword(s):  
Fluorescent Dyes ◽  
Dynamic Range ◽  
Low Cost ◽  
High Sensitivity ◽  
Receptor Expression ◽  
Label Free ◽  
Protein Protein Interaction ◽  
Small Molecule Screening ◽  
Guided Mode ◽  
Wide Range

Screening of biochemical interactions becomes simpler, less expensive, and more accurate when labels, such as fluorescent dyes, radioactive markers, and colorimetric reactions, are not required to quantify detected material. SRU Biosystems has developed a biosensor technology that is manufactured on continuous sheets of plastic film and incorporated into standard microplates and microarray slides to enable label-free assays to be performed with high throughput, high sensitivity, and low cost per assay. The biosensor incorporates a narrow band guided-mode resonance reflectance filter, in which the reflected color is modulated by the attachment/detachment of biochemical material to the surface. The technology offers 4 orders of linear dynamic range and uniformity within a plate, with a coefficient of variation of 2.5%. Using conventional biochemical immobilization surface chemistries, a wide range of assay applications are enabled. Small molecule screening, cell proliferation/cytotoxicity, enzyme activity screening, protein-protein interaction, and cell membrane receptor expression are among the applications demonstrated.

scholarly journals Integrating high-performing electrochemical transducers in lateral flow assay

2021 ◽  
Author(s):  
Antonia Perju ◽  
Nongnoot Wongkaew
Keyword(s):  
High Performance ◽  
Point Of Care ◽  
Low Cost ◽  
High Sensitivity ◽  
Lateral Flow ◽  
Analytical Performance ◽  
Label Free ◽  
High Performing ◽  
Lateral Flow Assays ◽  
Electrochemical Transducers

AbstractLateral flow assays (LFAs) are the best-performing and best-known point-of-care tests worldwide. Over the last decade, they have experienced an increasing interest by researchers towards improving their analytical performance while maintaining their robust assay platform. Commercially, visual and optical detection strategies dominate, but it is especially the research on integrating electrochemical (EC) approaches that may have a chance to significantly improve an LFA’s performance that is needed in order to detect analytes reliably at lower concentrations than currently possible. In fact, EC-LFAs offer advantages in terms of quantitative determination, low-cost, high sensitivity, and even simple, label-free strategies. Here, the various configurations of EC-LFAs published are summarized and critically evaluated. In short, most of them rely on applying conventional transducers, e.g., screen-printed electrode, to ensure reliability of the assay, and additional advances are afforded by the beneficial features of nanomaterials. It is predicted that these will be further implemented in EC-LFAs as high-performance transducers. Considering the low cost of point-of-care devices, it becomes even more important to also identify strategies that efficiently integrate nanomaterials into EC-LFAs in a high-throughput manner while maintaining their favorable analytical performance.

scholarly journals The effect of plasma functionalization on the print performance and time stability of graphite nanoplatelet electrically conducting inks

2020 ◽  
Author(s):  
Andrew Claypole ◽  
James Claypole ◽  
Tim Claypole ◽  
David Gethin ◽  
Liam Kilduff
Keyword(s):  
Printed Electronics ◽  
Low Cost ◽  
Electrical Performance ◽  
Graphite Nanoplatelets ◽  
Interparticle Interactions ◽  
Electrically Conducting ◽  
Wide Range ◽  
Oscillatory Rheology ◽  
The Stability ◽  
Plasma Functionalization

Abstract Carbon-based pastes and inks are used extensively in a wide range of printed electronics because of their widespread availability, electrical conductivity and low cost. Overcoming the inherent tendency of the nano-carbon to agglomerate to form a stable dispersion is necessary if these inks are to be taken from the lab scale to industrial production. Plasma functionalization of graphite nanoplatelets (GNP) adds functional groups to their surface to improve their interaction with the polymer resin. This offers an attractive method to overcome these problems when creating next generation inks. Both dynamic and oscillatory rheology were used to evaluate the stability of inks made with different loadings of functionalized and unfunctionalized GNP in a thin resin, typical of a production ink. The rheology and the printability tests showed the same level of dispersion and electrical performance had been achieved with both functionalized and unfunctionalized GNPs. The unfunctionalized GNPs agglomerate to form larger, lower aspect particles, reducing interparticle interactions and particle–medium interactions. Over a 12-week period, the viscosity, shear thinning behavior and viscoelastic properties of the unfunctionalized GNP inks fell, with decreases in viscosity at 1.17 s−1 of 24, 30, 39% for the ϕ = 0.071, 0.098, 0.127 GNP suspensions, respectively. However, the rheological properties of the functionalized GNP suspensions remained stable as the GNPs interacted better with the polymer in the resin to create a steric barrier which prevented the GNPs from approaching close enough for van der Waals forces to be effective.

Ultrasensitive colorimetric detection of Hg2+ ions based on enhanced catalytic performance of gold amalgam dispersed in channels of rose petals

The Analyst ◽  
2019 ◽  
Vol 144 (4) ◽  
pp. 1205-1209 ◽  
Author(s):  
Chi Zhang ◽  
Caiyun Kong ◽  
Qingyun Liu ◽  
Zhengbo Chen
Keyword(s):  
Gold Nanoparticles ◽  
Pore Structure ◽  
Low Cost ◽  
Colorimetric Detection ◽  
Catalytic Performance ◽  
Mercury Ions ◽  
Colorimetric Sensing ◽  
Rose Petals

We herein present a simple, low-cost, and ultrasensitive colorimetric sensing strategy for the detection of mercury ions (Hg2+) that takes advantage of the natural pore structure in rose petals to encapsulate gold nanoparticles (AuNPs).

scholarly journals Programmable Paper-Based Microfluidic Devices for Biomarker Detections

Micromachines ◽  
2019 ◽  
Vol 10 (8) ◽  
pp. 516 ◽  
Author(s):  
Veasna Soum ◽  
Sooyong Park ◽  
Albertus Ivan Brilian ◽  
Oh-Sun Kwon ◽  
Kwanwoo Shin
Keyword(s):  
Point Of Care ◽  
High Sensitivity ◽  
Microfluidic Devices ◽  
Portable Devices ◽  
Biomarker Detection ◽  
Fluid Delivery ◽  
Wide Range ◽  
Paper Based Microfluidics ◽  
Digital Microfluidic ◽  
Detection Of Biomarkers

Recent advanced paper-based microfluidic devices provide an alternative technology for the detection of biomarkers by using affordable and portable devices for point-of-care testing (POCT). Programmable paper-based microfluidic devices enable a wide range of biomarker detection with high sensitivity and automation for single- and multi-step assays because they provide better control for manipulating fluid samples. In this review, we examine the advances in programmable microfluidics, i.e., paper-based continuous-flow microfluidic (p-CMF) devices and paper-based digital microfluidic (p-DMF) devices, for biomarker detection. First, we discuss the methods used to fabricate these two types of paper-based microfluidic devices and the strategies for programming fluid delivery and for droplet manipulation. Next, we discuss the use of these programmable paper-based devices for the single- and multi-step detection of biomarkers. Finally, we present the current limitations of paper-based microfluidics for biomarker detection and the outlook for their development.

Fabrication of Precise Asymmetric Nanoshells Array with Nanogaps for a Label-Free Immunoassay Based on NIR-Light Responsive LSPR

2012 ◽  
Vol 523-524 ◽  
pp. 680-685
Author(s):  
Shuhei Uchida ◽  
Kazuya Yamamura ◽  
Nobuyuki Zettsu
Keyword(s):  
Near Infrared ◽  
Atmospheric Pressure Plasma ◽  
High Sensitivity ◽  
Medical Diagnostics ◽  
Localized Surface Plasmon ◽  
Label Free ◽  
Fabrication Technique ◽  
Alternative Structures ◽  
Wide Range ◽  
Surrounding Refractive Index

Localized surface plasmon resonance (LSPR) based sensors are a well established technology utilized for label-free biochemical sensing in immunoassay, medical diagnostics and environmental monitoring. The understanding of asymmetric metal nanoparticles, new object for complex, coupled plasmon systems providing localized significantly enhanced E-field, is central to a wide range of novel applications and processes in science of higher sensitive sensing systems. However, few methods are available for actual characterization of such nanostructures at the single particle level. Here we propose a precise and large sized scale fabrication technique for asymmetric nanoshells array with nanogaps of several tens of nanometers for LSPR sensor through atmospheric pressure plasma etching processes. A nanoshell was simply constructed by laminating thin Au films on periodic isolated polymer nanoparticles template. This nanoshells array was expected to exhibit specific near-infrared plasmonic properties. When measuring the sensitivity, nanoshells array exhibited a high sensitivity to changes of surrounding refractive index and showed a higher sensor figure of merit than the alternative structures. This indicated that the enhanced plasmon E-field in the asymmetric nanostructures improved sensor performance. Our fabrication technique and the optical properties of the arrays will provide useful information for developing new plasmonic applications.

scholarly journals Label free colorimetric sensing of thiocyanate based on inducing aggregation of Tween 20-stabilized gold nanoparticles

The Analyst ◽  
2012 ◽  
Vol 137 (11) ◽  
pp. 2682 ◽  
Author(s):  
Zhiyang Zhang ◽  
Jun Zhang ◽  
Chengli Qu ◽  
Dawei Pan ◽  
Zhaopeng Chen ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Tween 20 ◽  
Label Free ◽  
Colorimetric Sensing

Simulation of Gold Nanoparticles Aggravating MEMS Cantilever Optical Static Detection Biochip

2013 ◽  
Vol 694-697 ◽  
pp. 966-970 ◽  
Author(s):  
Yue Tao Ge ◽  
Xiao Tong Yin
Keyword(s):  
Gold Nanoparticles ◽  
Low Cost ◽  
Mechanical Systems ◽  
Side Wall ◽  
High Sensitivity ◽  
Detection Sensitivity ◽  
Gene Detection ◽  
Micro Electro Mechanical Systems ◽  
Target Dna ◽  
Static Detection

A kind of gene detection biochip model based on biological micro electro mechanical systems (BioMEMS) technology and micro optical electro mechanical systems (MOEMS) technology is designed and simulated. In order to detect whether there are nucleic acid components in the testing samples, the biochip in this study issues horizontal light by laser, then receives and reads the deformation signals of MEMS cantilever by optical detector. The MEMS optical reflecting system can amplify MEMS cantilever deformation signal 22 times by micro reflectors which are set on the side wall of the cantilever free end. In order to improve optical detection sensitivity, gold nanoparticles (GNPs) which are combined with hybridization information is taken to aggravate MEMS cantilever, and employ Au - S chemical bond of GNPs and dithiol HS(CH2)6SH to combine and fix DNA probe, and then employ target DNA which is marked with biotin to combine GNPs by Biotin - Streptavidin combining. The simulation results show that this biochip can detect biological samples fast, high throughput, low cost, high sensitivity and reliably.

Gas Sensing Properties of TiO2 and SnO2 Nanopowders Obtained through Gel Combustion

2006 ◽  
Vol 45 ◽  
pp. 1828-1833
Author(s):  
Fabio A. Deorsola ◽  
P. Mossino ◽  
Ignazio Amato ◽  
Bruno DeBenedetti ◽  
A. Bonavita ◽  
...  
Keyword(s):  
Response Time ◽  
Metal Oxides ◽  
Gas Sensing ◽  
Low Cost ◽  
High Sensitivity ◽  
Fast Response ◽  
High Specific Surface Area ◽  
Research Field ◽  
Wide Range ◽  
Gel Combustion

Nanostructured semiconductor metal oxides have played a central role in the gas sensing research field, because of their high sensitivity, selectivity and low response time. Among all the processes, developed for the synthesis of nanostructured metal oxides, gel combustion seems to be the most promising route due to low-cost precursors and simplicity of the process. It combines chemical gelation and combustion, involving the formation of a gel from an acqueous solution and an exothermic redox reaction, yielding to very porous and softly agglomerated nanopowders. In this work, nanostructured tin oxide, SnO2, and titanium oxide, TiO2, have been synthesized through gel combustion. Powders showed nanometric particle size and high specific surface area. The so-obtained TiO2 and SnO2 nanopowders have been used as sensitive element of resistive λ sensor and ethanol sensor respectively, realized depositing films of nanopowders dispersed in water onto alumina substrates provided with Pt contacts and heater. TiO2-based sensors showed at high temperature good response, fast response time, linearity in a wide range of O2 concentration and long-term stability. SnO2-based sensors have shown high sensitivity to low concentrations of ethanol at moderate temperature.

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