Optimization of Enzymatic Logic Gates and Networks for Noise Reduction and Stability

Biochemical computing attempts to process information with biomolecules and biological objects. In this work we review our results on analysis and optimization of single biochemical logic gates based on enzymatic reactions, and a network of three gates, for reduction of the "analog" noise buildup. For a single gate, optimization is achieved by analyzing the enzymatic reactions within a framework of kinetic equations. We demonstrate that using co-substrates with much smaller affinities than the primary substrate, a negligible increase in the noise output from the logic gate is obtained as compared to the input noise. A network of enzymatic gates is analyzed by varying selective inputs and fitting standardized few-parameters response functions assumed for each gate. This allows probing of the individual gate quality but primarily yields information on the relative contribution of the gates to noise amplification. The derived information is then used to modify experimental single gate and network systems to operate them in a regime of reduced analog noise amplification.Comment: 7 pages in PD

Simultaneous Quantification of Paracetamol and Meloxicam in Tablets by High Performance Liquid Chromatography

Purpose: To develop and validate a simple, rapid and inexpensive RP-HPLC method for the simultaneous estimation of paracetamol and meloxicam in tablets.Methods: For the analysis of the drugs, chromatographic analysis was performed on XTerra symmetry C18 column (100 × 4.6 mm, 5 μ particle size) with mobile phase consisting of methanol and phosphate buffer (pH 9.2) in the ratio of 50:50 v/v, at a flow rate of 0.8 mL/min and eluents monitored at 244 nm. The method was validated for linearity, accuracy, precision, robustness and application for assay as per International Conference on Harmonization (ICH) guidelines.Results: The retention times of paracetamol and meloxicam were 2.467 and 4.971 min, respectively. The calibration curves of peak area versus concentration, which was linear from 5 - 60 μg/mL for paracetamol and 1 - 12 μg/mL for meloxicam, had regression coefficient (r2) greater than 0.999. The method had the requisite accuracy, precision, and robustness for simultaneous determination of paracetamol and meloxicam in tablets.Conclusion: The proposed method is simple, low-cost, accurate, precise and can be successfully employed in routine quality control for the simultaneous analysis of paracetamol and meloxicam in tablets.Keywords: Paracetamol, Meloxicam, RP-HPLC, Simultaneous analysis, Tablet

Developments in nanoparticles for use in biosensors to assess food safety and quality

The following will provide an overview on how advances in nanoparticle technology have contributed towards developing biosensors to screen for safety and quality markers associated with foods. The novel properties of nanoparticles will be described and how such characteristics have been exploited in sensor design will be provided. All the biosensor formats were initially developed for the health care sector to meet the demand for point-of-care diagnostics. As a consequence, research has been directed towards miniaturization thereby reducing the sample volume to nanolitres. However, the needs of the food sector are very different which may ultimately limit commercial application of nanoparticle based nanosensors. © 2014 Elsevier Ltd

Towards Biochemical Filter with Sigmoidal Response to pH Changes: Buffered Biocatalytic Signal Transduction

We realize a biochemical filtering process by introducing a buffer in a biocatalytic signal-transduction logic system based on the function of an enzyme, esterase. The input, ethyl butyrate, is converted into butyric acid-the output signal, which in turn is measured by the drop in the pH value. The developed approach offers a versatile "network element" for increasing the complexity of biochemical information processing systems. Evaluation of an optimal regime for quality filtering is accomplished in the framework of a kinetic rate-equation model.Comment: PDF, 23 page

2:1 Multiplexing Function in a Simple Molecular System

1-[(Anthracen-9-yl)methylene] thiosemicarbazide shows weak fluorescence due to a photo-induced electron transfer (PET) process from the thiosemicarbazide moiety to the excited anthracene. The anthracene emission can be recovered via protonation of the amine as the protonated aminomethylene as an electron-withdrawing group that suppresses the PET process. Similarly, chelation between the ligand and the metal ions can also suppress the PET process and results in a fluorescence enhancement (CHEF). When solvents are introduced as the third control, a molecular 2:1 multiplexer is constructed to report selectively the inputs. Therefore, a molecular 2:1 multiplexer is realized in a simple molecular system

Control of Noise in Chemical and Biochemical Information Processing

We review models and approaches for error-control in order to prevent the buildup of noise when gates for digital chemical and biomolecular computing based on (bio)chemical reaction processes are utilized to realize stable, scalable networks for information processing. Solvable rate-equation models illustrate several recently developed methodologies for gate-function optimization. We also survey future challenges and possible new research avenues.Comment: 39 pages, 8 figures, PD