Recent Advances in Electrochemical Chitosan-Based Chemosensors and Biosensors: Applications in Food Safety

Chitosan is a biopolymer derived from chitin. It is a non-toxic, biocompatible, bioactive, and biodegradable polymer. Due to its properties, chitosan has found applications in several and different fields such as agriculture, food industry, medicine, paper fabrication, textile industry, and water treatment. In addition to these properties, chitosan has a good film-forming ability which allows it to be widely used for the development of sensors and biosensors. This review is focused on the use of chitosan for the formulation of electrochemical chemosensors. It also aims to provide an overview of the advantages of using chitosan as an immobilization platform for biomolecules by highlighting its applications in electrochemical biosensors. Finally, applications of chitosan-based electrochemical chemosensors and biosensors in food safety are illustrated.

Lab-on-Paper Devices for Diagnosis of Human Diseases Using Urine Samples—A Review

In recent years, microfluidic lab-on-paper devices have emerged as a rapid and low-cost alternative to traditional laboratory tests. Additionally, they were widely considered as a promising solution for point-of-care testing (POCT) at home or regions that lack medical infrastructure and resources. This review describes important advances in microfluidic lab-on-paper diagnostics for human health monitoring and disease diagnosis over the past five years. The review commenced by explaining the choice of paper, fabrication methods, and detection techniques to realize microfluidic lab-on-paper devices. Then, the sample pretreatment procedure used to improve the detection performance of lab-on-paper devices was introduced. Furthermore, an in-depth review of lab-on-paper devices for disease measurement based on an analysis of urine samples was presented. The review concludes with the potential challenges that the future development of commercial microfluidic lab-on-paper platforms for human disease detection would face.

Recent Advances in Electrochemical Chitosan-Based Chemosensors and Biosensors: Applications in Food Safety

Chitosan is a biopolymer derived from chitin. It is a non-toxic, biocompatible, bioactive, and biodegradable polymer. Due to its properties, chitosan has found applications in several and different fields such as agriculture, food industry, medicine, paper fabrication, textile industry, and water treatment. In addition to these properties, chitosan has a good film-forming ability which allows it to be widely used for the development of sensors and biosensors. This review is focused on the use of chitosan for the formulation of electrochemical chemosensors. It also aims to provide an overview of the advantages of using chitosan as an immobilization platform for biomolecules by highlighting its applications in electrochemical biosensors. Finally, applications of electro-chemical chitosan-based chemosensors and biosensors in food safety are illustrated

Controllable arrangement of integrated obstacles in silicon microchannels etched in 25 wt.% TMAX

In this paper, fabrication of silicon microchannels with integrated obstacles by using 25 wt.% tetramethylammonium hydroxide (TMAH) aqueous solution at the temperature of 80?C is presented and analysed. We studied basic island patterns, which present union of two symmetrical parallelograms with the sides along predetermined crystallographic directions <n10> (2<n<8) and <100>. Acute angles of the parallelograms were smaller than 45?. We have derived analytical relations for determining dimensions of the integrated obstacles. The developed etching technique provides reduction of the distance between the obstacles. Before the experiments, we performed simulations of pattern etching based on the level set method and presented evolution of the etched basic patterns for the predetermined crystallographic directions <n10>. Combination of basic patterns with sides along the <610> and <100> crystallographic directions is used to fabricate a matrix of two row of silicon obstacles in a microchannel. We obtained a good agreement between the experimental results and simulations. Our results enable simple and cost-effective fabrication of various complex microfluidic silicon platforms with integrated obstacles.

Comparative Optimization of Cellulase and Laccase Enzymes in Deinking Process of Used Newspapers

The use of enzymes in the bio-deinking process of newspaper waste has promising potential. However, investigations on the concentration of enzyme combinations need to be carried out to obtain the optimum ratio of cellulase and laccase enzymes for the bio-deinking process of recycled newspapers. The mixture of the two enzymes at various ratios was used to remove the ink on paper pulp from used newspapers by mechanical disintegration method treatment and followed by the bio-deinking process in an incubator shaker. The characterization of functional groups, structures, and thermal properties of bio-deinked pulp paper was carried out by FTIR, XRD, DTG/TGA, and an analysis of the degree of brightness to the prepared paper. FTIR results confirmed three main components of papers, such as cellulose, hemicellulose, and lignin. The XRD results showed that the equal ratio of cellulase and laccase enzymes had an effect on a higher crystallinity index, which was 78.8% compared to those obtained from the conventional methods with a crystallinity index of 69.7%. Thermal analysis showed that the optimum combination of both enzymes contributed the most at the highest temperature where the rate of degradation decreased. Brightness analysis showed that bio-deinking had met the quality requirements for newsprint paper in SNI 7273:2008. Our findings show that the combination of cellulase and laccase enzymes at the same ratio can produce optimal bio-deinked pulp for paper fabrication with excellent characteristics in brightness, thermal, and physical properties.