Current advancements and future perspectives of immunotherapy in colorectal cancer research.

When operating M/NEMS mass resonant sensors in the nonlinear regime, most of detection is based on the shift in the resonant frequency due to mass adsorption, as implemented in linear regime. This paper investigates an alternative mass detection based on the hysteretic behavior of the nonlinear frequency responses that takes advantage of bi-stability and bifurcations. A finite-degree-of-freedom reduced-order model of an electrostatically-actuated clamped-clamped microbeam is considered. Numerical results show that sudden jumps in amplitude make the detection of very small mass possible. Another interesting feature lies in the fact that the limit of detection can be set with the value of the operating frequency. However, it appears that this bifurcation-based mass detection does not exhibit the expected robustness. A possible improvement is proposed, based on the reinitialization of the system by a forced jump-down on the hysteretic response curve.

https://hal.archives-ouvertes.fr/hal-00935666/document

Bifurcation-based micro/nano-electromechanical mass detection

Graphene quantum dot-gold hybrid nanoparticles integrated aptasensor for ultra-sensitive detection of vitamin D3 towards point-of-care application

This work describes the design and development process of an immunosensor. The creation of such devices goes through various steps, which complement each other, and choosing an efficient immobilization method that binds to a specific target is essential to achieve satisfactory diagnostic results. In this perspective, the emphasis here is on developing biosensors based on binding antigens/antibodies on particular surfaces of magneto-elastic sensors. Different aspects leading to the improvement of these sensors, such as the antibody structure, the chemical functionalization of the surface, and cross-linking antibody reticulation were summarized and discussed. This paper deals with the progress of magneto-elastic immunosensors to detect bacterial pathogens and associated toxins. Biologically modified surface characterization methods are further considered. Thus, research opportunities and trends of future development in these areas are finally discussed.

Antibody-based magneto-elastic biosensors: potential devices for detection of pathogens and associated toxins

Electrochemical impedance spectroscopy (EIS) is a common method in biosensing detection of pathogens for public health and safety. In its most general form, increases of charge transfer resistance or decrease of double layer capacitance at the interface are used for reporting EIS system changes due to pathogens. However, this strategy is not universally adaptable to various EIS sensors and could lead to inaccurate detection. Herein, we demonstrated a machine learning-based EIS biosensor for E.coli detection with improved accuracy. EIS data was obtained from gold electrodes immobilized with E.coli through antibody binding and fitted with the Randles model to extrapolate multiple impedimetric parameters. A machine learning model, using principle component analysis and support vector regression, was trained to automatically establish a quantitative relationship between multiple impedimetric parameters and bacterial concentrations. Results showed an improved accuracy in determining bacterial concentration. The improvement is due to the integration of both capacitance and resistance information. These results thus pave the way for automatic and accurate EIS biosensors in various applications.

Electrochemical Impedance Spectroscopic Detection of E.coli with Machine Learning

Self-assembled monolayer (SAM) of n-alkanethiols of different chain lengths (n = 2, 3, 6, 11, 16) on a gold surface are used to immobilize antibodies which in turn bind to a antigen. The antibody and antigen used in this study have similar molecular weights i.e. ∼150 kDa. The antibody [1.5 μg cm−2] immobilized varied with the surface packing density of the SAM of carboxylic acid-terminated n-alkanethiols of different lengths. In comparison, the efficiency of antibody immobilization was lowest on the loosely packed SAM of n-alkanethiols (n ≤ 3) and the highest on the densely packed SAM of n-alkanethiols (n ≥ 11). However, increased immobilization of antibodies with increasing chain length of the n-alkanethiols [n > 11], did not result in a corresponding increase in antigen binding. An attempt to explain this phenomenon based on packing density and an orientation of the captured antibody is presented.

Studies on varying n-alkanethiol chain lengths on a gold coated surface and their effect on antibody-antigen binding efficiency

Selective transportation of charged ZnO nanoparticles and microorganism dialysis through silicon nanoporous membranes

Immobilizing Siderophores on Solid Surfaces for Bacterial Detection

Cantilevers immersed in liquid experience viscous damping and hydrodynamic loading. We report on the use of such cantilevers, operating in the dynamic mode with, (i) frequency sweeping and (ii) phase locked loop methods. The solution to reliability issues such as random drift in the resonant peak values, and interference of spurious modes in the resonance frequency spectrum, are explained based on the actuation signal provided and laser spot size. The laser beam spot size and its position on the cantilever were found to have an important role, on the output signal and resonance frequency. We describe a method to distinguish the normal modes from the spurious modes for a cantilever. Uncertainties in the measurements define the lower limit of mass detection (m min). The minimum detection limits of the two measurement methods are investigated by measuring salt adsorption from phosphate buffer solution, as an example, a mass of 14 pg was measured using the 14th transverse mode of a m × 100 μm × 1 μm silicon cantilever. The optimized measurement was used to study the interaction between antibody and antigen.

Priyanka Bhadra

Papers

Current advancements and future perspectives of immunotherapy in colorectal cancer research.

Studies on varying n-alkanethiol chain lengths on a gold coated surface and their effect on antibody-antigen binding efficiency

Selective transportation of charged ZnO nanoparticles and microorganism dialysis through silicon nanoporous membranes

Immobilizing Siderophores on Solid Surfaces for Bacterial Detection

Measurement and reliability issues in resonant mode cantilever for bio-sensing application in fluid medium