Sensors For Detection Of Biomolecules Research Articles

One-Step Rapid Synthesis of Al-Based Ag Dendrites for Highly Active and Cost Effective SERS Plasmonic Substrates

Highly active Al-based Ag dendrites SERS plasmonic substrates have been rapidly synthesized by the one-step galvanic displacement reaction without the use of any surfactants and templates. The as-prepared SERS substrates were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman spectroscopy. XRD measurements confirmed the metallic nature of the formed Ag dendrites. None of the organic additives were used in the synthesis process, which ensures the substrates surfaces are completely clean and avoiding the introduction of organic contaminants. The innovative rough bionic substrates yield a final silver dendritic structure that offers large specific surface area and high-density hotspots. Using malachite green as a model target, the Al-based Ag dendrites SERS substrates exhibited acceptable reproducibility (relative standard deviation of 23.8%) and high enhancement capacities (pushed the detection limit down to 10 pM). Importantly, these Ag dendrites could potentially be employed as highly active and cost effective flexible SERS sensors for label-free ultrasensitive detection of biomolecules.

Numerical Modelling of a Nanopore-based Resistive-Pulse Sensor for Detection of Biomolecules.

Resistive pulse sensors (RPS) are based on the detection principle of partial and non-permanent obstruction of an electrically conducting channel. The integration of RPS in microfluidics has the potential for detections at the molecular level. Current challenges involve limitations in fabrication technology, most notably the finite structure accuracy and fabrication repeatability, which have a direct and strong impact on RPS device performance. In this work, we analyzed the geometrical structure and performance of a nanofabricated RPS device and iteratively used the experimental data to propose an adequate numerical model which also accounts for fabrication imperfections beyond the optical resolution limit. The proposed model for a nano-RPS was validated and able to augment the understating of the structure and operation of a microdevice.Clinical Relevance- This work is part of a greater effort to bring microfluidics devices closer to patients for bedside analysis of blood, or other human fluids, for instance. These devices can potentially perform screening for multiple targets in one sample. New devices often need to go through design, prototyping and bench tests, simulation models as the one presented can increase the chances of the device to get to the market in reduced time.

Investigation of Serially Coupled Double Microsphere Sensor for Detection of Biomolecules

Microsphere sensors have attracted increasing attention in recent years especially in label-free detection of biomolecules thanks to their very high quality factors which causes to have the high sensitivity and low detection limit. In this paper, two novel structures for microsphere sensors based on serially coupling of two microspheres are proposed. They are modeled using directional coupling theory while considering the loss condition in biosensing applications. The proposed structures are simulated for sensing rodlike bacteria and their key sensing parameters are compared with a single-microsphere sensor. It is demonstrated that by using serially coupled double microsphere sensor, the frequency spacing between adjacent resonances observed at the output spectrum of the sensor is expanded considerably compared to the single-microsphere sensor and therefore it is much easier to track the resonance frequencies variation due to changes in the surrounding medium while the sensor's quality factor remains high.

Boronic Acid-Based Electrochemical Sensors for Detection of Biomolecules

Boronic Acid-Based Electrochemical Sensors for Detection of Biomolecules

Single molecule SERS and detection of biomolecules with a single gold nanoparticle on a mirror junction

Using the bianalyte method we unambiguously demonstrate that a single gold nanosphere on a metal film junction, in the so-called nanoparticle on a mirror configuration, is capable of single molecule detection with surface-enhanced Raman spectroscopy (SERS). Also this configuration serves as a convenient and highly sensitive SERS sensor for detection of biomolecules. Such simple nano-junction based systems are ideal for chemical and biomedical analysis.

Highly sensitive field effect charge sensor for direct detection of biomolecules

A field effect transistor (FET) charge sensor is proposed to work at a special operating condition in order to become extremely sensitive to the gate charge change caused by biomolecules. A device model has been established and the simulation results justify the hypothesis. It is found that at the depletion operating condition the proposed FET charge sensor will shift a gate voltage up to 1 mV in response to every electron per square micron, which is much more sensitive than other existing FET sensors.

Development of Reticulated Vitreous Carbon Based Electrochemical Sensor for Detection of Biomolecules.

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Magnetic GMI sensor for detection of biomolecules

A magnetic sensor based on the giant magnetoimpedance (GMI) effect for the detection of biomolecules was made with a CoFeSiB amorphous magnetic microwire as sensing element. Using soft ferromagnetic cobalt microparticles and field sensitivities of the impedance of about 2.5%/A m −1 in the very low field region (less than 200 A m −1) at frequencies close to 10 MHz, a highly sensitive response was measured, appropriate for the detection of low biomolecule concentrations.