Development of a new and simple method for the detection of histidine-tagged proteins based on thionine-chitosan/gold nanoparticles/horseradish peroxidase

Nanomaterial-based electrochemical sensors for detection of amino acids

Amino acids are the building blocks of proteins and muscle tissue. They also play a significant role in physiological processes related to energy, recovery, mood, muscle and brain function, fat burning and stimulating growth hormone or insulin secretion. Accurate determination of amino acids in biological fluids is necessary because any changes in their normal ranges in the body warn diseases like kidney disease, liver disease, type 2 diabetes and cancer. To date, many methods such as liquid chromatography, fluorescence mass spectrometry, etc. have been used for the determination of amino acids. Compared with the above techniques, electrochemical systems using modified electrodes offer a rapid, accurate, cheap, real-time analytical path through simple operations with high selectivity and sensitivity. Nanomaterials have found many interests to create smart electrochemical sensors in different application fields e.g. biomedical, environmental, and food analysis because of their exceptional properties. This review summarizes recent advances in the development of nanomaterial-based electrochemical sensors in 2017-2022 for the detection of amino acids in various matrices such as serum, urine, blood and pharmaceuticals.

Development of alkaline phosphatase-scFv and its use for one-step enzyme-linked immunosorbent assay for His-tagged protein detection

A histidine (His)-tag is composed of six His residues and typically exerts little influence on the structure and solubility of expressed recombinant fusion proteins. Purification methods for recombinant proteins containing His-tags are relatively well-established, thus His-tags are widely used in protein recombination technology. We established a one-step enzyme-linked immunosorbent assay (ELISA) for His-tagged recombinant proteins. We analyzed variable heavy and light chains of the anti-His-tag monoclonal antibody 4C9 and used BLAST analyses to determine variable zones in light (VL) and heavy chains (VH). VH, VL, and alkaline phosphatase (ALP) regions were connected via a linker sequence and ligated into the pGEX-4T-1 expression vector. Different recombinant proteins with His tags were used to evaluate and detect ALP-scFv activity. Antigen and anti-His-scFv-ALP concentrations for direct ELISA were optimized using the checkerboard method. ZIKV-NS1, CHIKV-E2, SCRV-N, and other His-tag fusion proteins demonstrated specific reactions with anti-His-scFv-ALP, which were accurate and reproducible when the antigen concentration was 50 µg mL−1 and the antibody concentration was 6.25 µg mL−1. For competitive ELISA, we observed a good linear relationship when coating concentrations of recombinant human anti-Müllerian hormone (hAMH) were between 0.78 and 12.5 µg mL−1. Our direct ELISA method is simple, rapid, and accurate. The scFv antibody can be purified using a prokaryotic expression system, which provides uniform product quality and reduces variations between batches.

Nanostructured materials for harnessing the power of horseradish peroxidase for tailored environmental applications

High catalytic efficiency, stereoselectivity, and sustainability outcomes of enzymes entice chemists for considering biocatalytic transformations to supplant conventional synthetic routes. As a green and versatile enzyme, horseradish peroxidase (HRP)-based enzymatic catalysis has been widely employed in a range of biological and chemical transformation processes. Nevertheless, like many other enzymes, HRP is likely to denature or destabilize in harsh realistic conditions due to its intrinsic fragile nature, which results in inevitably shortened lifespan and immensely high bioprocess cost. Enzyme immobilization has proven as a prospective strategy for improving their biocatalytic performance in continuous industrial processes. Nanostructured materials with huge accessible surface area, abundant porous structures, exceptional functionalities, and high chemical and mechanical stability have recently garnered intriguing research interests as novel kinds of supporting matrices for HRP immobilization. Many reported immobilized biocatalytic systems have demonstrated high catalytic performances than that to the free form of enzymes, such as enhanced enzyme efficiency, selectivity, stability, and repeatability due to the protective microenvironments provided by nanostructures. This review delineates an updated overview of HRP immobilization using an array of nanostructured materials. Furthermore, the general physicochemical aspects, improved catalytic attributes, and the robust practical implementations of engineered HRP-based catalytic cues are also discussed with suitable examples. To end, concluding remarks, challenges, and worthy suggestions/perspectives for future enzyme immobilization are also given.

Nature-derived materials for the fabrication of functional biodevices

Nature provides an incredible source of inspiration, structural concepts, and materials toward applications to improve the lives of people around the world, while preserving ecosystems, and addressing environmental sustainability. In particular, materials derived from animal and plant sources can provide low-cost, renewable building blocks for such applications. Nature-derived materials are of interest for their properties of biodegradability, bioconformability, biorecognition, self-repair, and stimuli response. While long used in tissue engineering and regenerative medicine, their use in functional devices such as (bio)electronics, sensors, and optical systems for healthcare and biomonitoring is finding increasing attention. The objective of this review is to cover the varied nature derived and sourced materials currently used in active biodevices and components that possess electrical or electronic behavior. We discuss materials ranging from proteins and polypeptides such as silk and collagen, polysaccharides including chitin and cellulose, to seaweed derived biomaterials, and DNA. These materials may be used as passive substrates or support architectures and often, as the functional elements either by themselves or as biocomposites. We further discuss natural pigments such as melanin and indigo that serve as active elements in devices. Increasingly, combinations of different biomaterials are being used to address the challenges of fabrication and performance in human monitoring or medicine. Finally, this review gives perspectives on the sourcing, processing, degradation, and biocompatibility of these materials. This rapidly growing multidisciplinary area of research will be advanced by a systematic understanding of nature-inspired materials and design concepts in (bio)electronic devices.