scholarly journals Nanoparticle Determination in Water by LED-Excited Surface Plasmon Resonance Imaging

Chemosensors ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 175
Author(s):  
Lukas Wunderlich ◽  
Peter Hausler ◽  
Susanne Märkl ◽  
Rudolf Bierl ◽  
Thomas Hirsch
Keyword(s):  
Light Source ◽  
Self Assembled Monolayers ◽  
Receptor Interaction ◽  
Complex Nature ◽  
Label Free ◽  
Quality Of Water ◽  
Spr Imaging ◽  
Online Sensor ◽  
Assembled Monolayers

The increasing popularity of nanoparticles in many applications has led to the fact that these persistent materials pollute our environment and threaten our health. An online sensor system for monitoring the presence of nanoparticles in fresh water would be highly desired. We propose a label-free sensor based on SPR imaging. The sensitivity was enhanced by a factor of about 100 by improving the detector by using a high-resolution camera. This revealed that the light source also needed to be improved by using LED excitation instead of a laser light source. As a receptor, different self-assembled monolayers have been screened. It can be seen that the nanoparticle receptor interaction is of a complex nature. The best system when taking sensitivity as well as reversibility into account is given by a dodecanethiol monolayer on the gold sensor surface. Lanthanide-doped nanoparticles, 29 nm in diameter and with a similar refractive index to the most common silica nanoparticles were detected in water down to 1.5 µg mL−1. The sensor can be fully regenerated within one hour without the need for any washing buffer. This sensing concept is expected to be easily adapted for the detection of nanoparticles of different size, shape, and composition, and upon miniaturization, suitable for long-term applications to monitor the quality of water.

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.

Long-Term Stability of Self-Assembled Monolayers in Biological Media

Langmuir ◽  
2003 ◽  
Vol 19 (26) ◽  
pp. 10909-10915 ◽  
Author(s):  
Nolan T. Flynn ◽  
Thanh Nga T. Tran ◽  
Michael J. Cima ◽  
Robert Langer
Keyword(s):  
Self Assembled Monolayers ◽  
Biological Media ◽  
Term Stability ◽  
Long Term Stability ◽  
Assembled Monolayers ◽  
Self Assembled

Peptide Self-Assembled Monolayers for Label-Free and Unamplified Surface Plasmon Resonance Biosensing in Crude Cell Lysate

2009 ◽  
Vol 81 (16) ◽  
pp. 6779-6788 ◽  
Author(s):  
Olivier R. Bolduc ◽  
Christopher M. Clouthier ◽  
Joelle N. Pelletier ◽  
Jean-François Masson
Keyword(s):  
Surface Plasmon Resonance ◽  
Surface Plasmon ◽  
Plasmon Resonance ◽  
Self Assembled Monolayers ◽  
Label Free ◽  
Crude Cell Lysate ◽  
Cell Lysate ◽  
Assembled Monolayers ◽  
Self Assembled

scholarly journals Increased Stability of Glycol-Terminated Self-Assembled Monolayers for Long-Term Patterned Cell Culture

Langmuir ◽  
2012 ◽  
Vol 28 (9) ◽  
pp. 4318-4324 ◽  
Author(s):  
Matthew K. Strulson ◽  
Dawn M. Johnson ◽  
Joshua A. Maurer
Keyword(s):  
Cell Culture ◽  
Self Assembled Monolayers ◽  
Assembled Monolayers ◽  
Self Assembled

scholarly journals Variations in the structure and reactivity of thioester functionalized self-assembled monolayers and their use for controlled surface modification

2012 ◽  
Vol 3 ◽  
pp. 213-220 ◽  
Author(s):  
Inbal Aped ◽  
Yacov Mazuz ◽  
Chaim N Sukenik
Keyword(s):  
Surface Modification ◽  
Structural Diversity ◽  
Self Assembled Monolayers ◽  
Wetting Properties ◽  
Long Term Storage ◽  
Assembled Monolayers ◽  
Important Approach ◽  
Self Assembled ◽  
Term Storage

Thioester-functionalized, siloxane-anchored, self-assembled monolayers provide a powerful tool for controlling the chemical and physical properties of surfaces. The thioester moiety is relatively stable to long-term storage and its structure can be systematically varied so as to provide a well-defined range of reactivity and wetting properties. The oxidation of thioesters with different-chain-length acyl groups allows for very hydrophobic surfaces to be transformed into very hydrophilic, sulfonic acid-bearing, surfaces. Systematic variation in the length of the polymethylene chain has also allowed us to examine how imbedding reaction sites at various depths in a densely packed monolayer changes their reactivity. π-Systems (benzene and thiophene) conjugated to the thioester carbonyl enable the facile creation of photoreactive surfaces that are able to use light of different wavelengths. These elements of structural diversity combine with the utility of the hydrophilic, strongly negatively charged sulfonate-bearing surface to constitute an important approach to systematic surface modification.

Label-free C-reactive protein SERS detection with silver nanoparticle aggregates

RSC Advances ◽  
2015 ◽  
Vol 5 (44) ◽  
pp. 34720-34729 ◽  
Author(s):  
Hyunmin Kim ◽  
Eunjoo Kim ◽  
Eunsook Choi ◽  
Chul Su Baek ◽  
Bokyung Song ◽  
...  
Keyword(s):  
Silver Nanoparticle ◽  
Qualitative Approach ◽  
Self Assembled Monolayers ◽  
Label Free ◽  
C Reactive Protein ◽  
Reactive Protein ◽  
Assembled Monolayers ◽  
Nanoparticle Aggregates ◽  
Sers Detection ◽  
Self Assembled

In this work, we report a qualitative approach for detecting the adsorption of C-reactive protein on phosphocholine-terminated self-assembled monolayers without the use of any labels.

scholarly journals Label-Free Screening of SARS-CoV-2 NSP14 Exonuclease Activity Using SAMDI Mass Spectrometry

2021 ◽  
pp. 247255522110088
Author(s):  
Michael D. Scholle ◽  
Cheng Liu ◽  
Jerome Deval ◽  
Zachary A. Gurard-Levin
Keyword(s):  
Mass Spectrometry ◽  
Drug Discovery ◽  
High Throughput ◽  
Nonstructural Protein ◽  
Self Assembled Monolayers ◽  
Ionization Mass ◽  
Label Free ◽  
Assembled Monolayers ◽  
High Throughput Assay ◽  
First Time

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the virus responsible for the global COVID-19 pandemic. Nonstructural protein 14 (NSP14), which features exonuclease (ExoN) and guanine N7 methyltransferase activity, is a critical player in SARS-CoV-2 replication and fidelity and represents an attractive antiviral target. Initiating drug discovery efforts for nucleases such as NSP14 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 NSP14 ExoN activity. The assay was used to measure NSP14 activity and gain insight into substrate specificity and the reaction mechanism. Next, 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 > 200). Screening 10,240 small molecules from a diverse library revealed candidate inhibitors, which were counterscreened for NSP14 selectivity and RNA intercalation. The assay methodology described here will enable, for the first time, a label-free and high-throughput assay for NSP14 ExoN activity to accelerate drug discovery efforts and, due to the assay flexibility, can be more broadly applicable for measuring other enzyme activities from other viruses or implicated in various pathologies.

Functionalized Silicon Electrodes in Electrochemistry

2020 ◽  
Vol 13 (1) ◽  
pp. 135-158 ◽  
Author(s):  
Vinicius R. Gonçales ◽  
Jiaxin Lian ◽  
Shreedhar Gautam ◽  
Richard D. Tilley ◽  
J. Justin Gooding
Keyword(s):  
Electron Transfer ◽  
Thick Layer ◽  
Silicon Surfaces ◽  
Self Assembled Monolayers ◽  
Aqueous Electrolytes ◽  
Term Operation ◽  
Assembled Monolayers ◽  
Transfer Behavior ◽  
Passivated Silicon

Avoiding the growth of SiOx has been an enduring task for the use of silicon as an electrode material in dynamic electrochemistry. This is because electrochemical assays become unstable when the SiOx levels change during measurements. Moreover, the silicon electrode can be completely passivated for electron transfer if a thick layer of insulating SiOx grows on the surface. As such, the field of silicon electrochemistry was mainly developed by electron-transfer studies in nonaqueous electrolytes and by applications employing SiOx-passivated silicon-electrodes where no DC currents are required to cross the electrode/electrolyte interface. A solution to this challenge began by functionalizing Si–H electrodes with monolayers based on Si–O–Si linkages. These monolayers have proven very efficient to avoid SiOx formation but are not stable for a long-term operation in aqueous electrolytes due to hydrolysis. It was only with the development of self-assembled monolayers based on Si–C linkages that a reliable protection against SiOx formation was achieved, particularly with monolayers based on α,ω-dialkynes. This review discusses in detail how this surface chemistry achieves such protection, the electron-transfer behavior of these monolayer-modified silicon surfaces, and the new opportunities for electrochemical applications in aqueous solution.

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