Debopam Datta

A Graphene and Aptamer Based Liquid Gated FET-Like Electrochemical Biosensor to Detect Adenosine Triphosphate

Here we report successful demonstration of a FET-like electrochemical nano-biosensor to accurately detect ultralow concentrations of adenosine triphosphate. As a 2D material, graphene is a promising candidate due to its large surface area, biocompatibility, and demonstrated surface binding chemistries and has been employed as the conducting channel. A short 20-base DNA aptamer is used as the sensing element to ensure that the interaction between the analyte and the aptamer occurs within the Debye length of the electrolyte (PBS). Significant increase in the drain current with progressive addition of ATP is observed whereas for control experiments, no distinct change in the drain current occurs. The sensor is found to be highly sensitive in the nanomolar (nM) to micromolar ( μM) range with a high sensitivity of 2.55 μA (mM) -1, a detection limit as low as 10 pM, and it has potential application in medical and biological settings to detect low traces of ATP. This simplistic design strategy can be further extended to efficiently detect a broad range of other target analytes.

Submillimolar Detection of Adenosine Monophosphate Using Graphene-Based Electrochemical Aptasensor

In this paper, we present a successful demonstration of a graphene-based field-effect-transistor-like electrochemical nanobiosensor to accurately detect ultralow concentrations of adenosine monophosphate (AMP). Graphene being a two-dimensional material is a suitable option as a sensing element due to its biocompatibility and large surface area. It has also demonstrated surface binding chemistries as well as its ability to serve as a conducting channel. A short 20-base deoxyribonucleic acid (DNA) aptamer is used as the sensing element to ensure that the interaction between the analyte and the aptamer occurs within the Debye length of the electrolyte. The sensor is found to be nonlinear in nature and sensitive in the picomolar (pM) and nanomolar (nM) concentrations of AMP. The linear region of operation is found to be 1 nM–100 μM and percentage change in drain current in this concentration region is calculated as

Spontaneous polarization induced electric field in zinc oxide nanowires and nanostars

{\text{1.56}}{\boldsymbol{\% }}/{\boldsymbol{decade}}

Design and implementation of fast FPGA based architecture for reversible watermarking

. A minimum concentration of 10 pM of AMP has been detected using this type of sensor.

Graphene oxide and DNA aptamer based sub-nanomolar potassium detecting optical nanosensor

We report on the detection mechanism of spontaneous polarization using electrostatic force microscopy in zinc oxide nanowires and nanostars grown by vapor-liquid-solid technique. Optical and structural properties are investigated in detail to understand the complex ZnO nanostructures comprehensively. Calculations are carried out to estimate the electric field from the change in interleave amplitude induced by the electrostatic force due to the spontaneous polarization effects. Attraction of the probe between the tip and the sample varies for different structures with a stronger attraction for nanostars as compared to nanowires. Strength of electric field is dependent on the orientation of nanowires and nanostars c-axis with measured magnitude of electric field to be ∼107 V/m and 108 V/m respectively. This technique presents a unique detection mechanism of built-in spontaneous polarization and electric field from polar ZnO nanowires with applications in voltage gated ion channels, nano-bio interfaces, opto...

Biomedical Applications of Quantum Dots, Nucleic Acid-Based Aptamers, and Nanostructures in Biosensors.

There are diverse hardware realization for digital watermarking of multimedia proposed in the literature. This paper focuses on the design and implementation of a fast FPGA(Field Programmable Gate Array) based architecture using reversible contrast mapping (RCM) based image watermarking algorithm. The specialty of this architecture attracts to the fact of clock-less encoder design and implementation which makes the design faster. The encoder module response time is independent of clock frequency, so the embedding of the watermark is possible as soon as the input is fetched. The schematic based design and implementation of the VLSI architecture have been done with Xilinx 14.1 on Spartan 3E FPGA family. The encoder requires 528 4-input LUTs and 303 slices. On the contrary, the decoder requires 613 LUTs and 347 slices. The maximum clock frequency of the decoder is 45 MHz. The results show the viability of low cost, high speed realtime use of the proposed VLSI architecture.

Terahertz vibrational signature of bacterial spores arising from nanostructure decorated endospore surface

Quantum-dot (QD) based nanosensors are frequently used by researchers to detect small molecules, ions and different biomolecules. In this article, we present a sensor complex/system comprised of deoxyribonucleic acid (DNA) aptamer, gold nanoparticle and semiconductor QD, attached to a graphene oxide (GO) flake for detection of potassium. As reported herein, it is demonstrated that QD-aptamer-quencher nanosensor functions even when tethered to GO, opening the way to future applications where sensing can be accomplished simultaneously with other previously demonstrated applications of GO such as serving as a nanocarrier for drug delivery. Herein, it is demonstrated that the DNA based thrombin binding aptamer used in this study undergoes the conformational change needed for sensing even when the nanosensor complex is anchored to the GO. Analysis with the Hill equation indicates the interaction between aptamer and potassium follows sigmoidal Hill kinetics. It is found that the quenching efficiency of the optical sensor is linear with the logarithm of concentration from 1 pM to 100 nM and decreases for higher concentration due to unavailability of aptamer binding sites. Such a simple and sensitive optical aptasensor with minimum detection capability of 1.96 pM for potassium ion can also be employed in-vitro detection of different physiological ions, pathogens and disease detection methods.

Coupled acousto-optical phonons in wurtzites: Micro-to-nano-scale bridging

This review is a survey of the biomedical applications of semiconductor quantum dots, nucleic acid-based aptamers, and nanosensors as molecular biosensors. It focuses on the detection of analytes in biomedical applications using (1) advances in molecular beacons incorporating semiconductor quantum dots and nanoscale quenching elements; (2) aptamer-based nanosensors on a variety of platforms, including graphene; (3) Raman scattering and surface-enhanced Raman scattering (SERS) using nanostructures for enhanced SERS spectra of biomolecules, including aptamers; and (4) the electrical and optical properties of nanostructures incorporated into molecular beacons and aptamer-based nanosensors. Research done at the University of Illinois at Chicago (UIC) is highlighted throughout since it emphasizes the specific approaches taken by the bioengineering department at UIC.

Molecular beacon anchored onto a graphene oxide substrate

This theoretical effort is the first to explore the possible hypothesis that terahertz optical activity of Bacillus spores arises from normal vibrational modes of spore coat subcomponents in the terahertz frequency range. Bacterial strains like Bacillus and Clostridium form spores with a hardened coating made of peptidoglycan to protect its genetic material in harsh conditions. In recent years, electron microscopy and atomic force microscopy has revealed that bacterial spore surfaces are decorated with nanocylinders and honeycomb nanostructures. In this article, a simple elastic continuum model is used to describe the vibration of these nanocylinders mainly in Bacillus subtilis, which also leads to the conclusion that the terahertz signature of these spores arises from the vibration of these nanostructures. Three vibrating modes: radial/longitudinal, torsional and flexural, have been identified and discussed for the nanocylinders. The effect of bound water, which shifts the vibration frequency, is also discussed. The peptidoglycan molecule consists of polar and charged amino acids; hence, the sporal surface local vibrations interact strongly with the terahertz radiation.

Aptasensor based optical detection of glycated albumin for diabetes mellitus diagnosis

Frequently, in semiconductor physics, acoustic phonons and optical phonons in nanostructures are described using the elastic continuum model and the dielectric continuum model, respectively. In this article, we have used the Lagrangian formalism to develop a set of coupled differential equations for describing coupled acoustic-optical phonon modes for wurtzite crystal structures considering the anisotropy of the crystal. The quantization of phonon displacements is described as well as the mode normalization need to bridge between the micro-scale and the nano-scale.